EPA/600/R-94/178
September 1994
THE PRODUCT SIDE OF POLLUTION PREVENTION:
EVALUATING THE POTENTIAL FOR SAFE SUBSTITUTES
Gary A. Davis and Lori Kincaid
Dean Menke, Barbara Griffith, Sheila Jones, Katina Brown, and Margaret Goergen
The University of Tennessee
Center for Clean Products and Clean Technologies
Knoxville, Tennessee 37996-0710
EPA Cooperative Agreement No. CR-816735-01-1
Project Officer:
Emma Lou George
Waste Minimization, Destruction and Disposal Research Division
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
Printed on Recycled Paper
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DISCLAIMER
The information in this document has been funded wholly by the United States
Environmental Protection Agency under Cooperative Agreement CR #816735-01-0 to the
University of Tennessee's Center for Clean Products and Clean Technologies. It has been
subject to peer and administrative review, and has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.
11
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FOREWORD
Today's rapidly developing and changing technologies and industrial products and
practices frequently carry with them the increased generation of materials that, if improperly
dealt with, can threaten both public health and the environment. The U.S. Environmental
Protection Agency is charged by Congress with protecting the Nation's land, air and water
resources. Under a mandate or national environmental laws, the Agency strives to formulate
and implement actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. These laws direct EPA to perform
research to define our environmental problems, measure the impacts, and search for
solutions.
The Risk Reduction Engineering Laboratory is responsible for planning,
implementing, and managing research, development and demonstration programs to provide
an authoritative, defensible engineering basis in support of the policies, programs, and
regulations of the EPA with respect to drinking water, wastewater, pesticides, toxic
substances, solid and hazardous wastes, and Superfund-related activities. This, publication is
one of the products of that research and provides a vital communication link between the
researcher and the user community.
This report, The Product Side of Pollution Prevention: Evaluating the Potential for
Safe Substitutes, funded through the Pollution Prevention Research Branch, is a major project
in the area of the Cleaner Products Program in researching methods to support the design
and development of products whose manufacture, use, recycle and disposal represent reduced
impacts on the environment.
This report is an in-depth study of the potential for substituting safer or less toxic
chemicals for seventeen of the priority 33/50 chemicals from the Toxic Release Inventory.
Chemical use trees have been developed to display the primary uses and products
manufactured from these chemicals. From these chemicals use trees, seven priority product
categories have been developed and each of these categories is researched to provide timely
information on current releases, status of the manufacturing and projections of possibilities
for safer chemical substitutions and therefore source reduction of toxic chemical releases to
the environment. Product design from manufacturing, to marketing and ultimate disposal is
an integral component of the equation for innovative source reduction and responsible waste
management. The reader is encouraged to contact the authors or project officer for more
information concerning this project and report.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
in
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ABSTRACT
The hazardous waste problem and many of the persistent air and water pollution
problems are primarily toxic chemical problems. Widespread use of toxic chemicals in
industry and commerce has created the need to deal with toxic releases into the air, water
and contained in soil. Regulations have not sufficiently reduced environmental releases nor
have they protected workers for effects of these toxic agents in the workplace or consumers
from toxic chemicals found in products. Substitution of products and practices reducing use
of toxic chemicals can reduce hazardous waste generation, mitigate toxic air and water
pollution and reduce worker exposure and public exposure to toxic chemicals.
This report presents results to evaluate the possibility of dramatic reductions in toxic
chemical releases by focussing on safe substitutes for products that contain or use toxic
chemicals in their manufacturing process. Identifying priority products for substitution and
evaluating the feasibility of safe substitutes for those products is an important step in the shift
toward prevention of toxic chemical pollution at the source.
This report illustrates that the generation of hazardous waste and toxic pollutants is
the choice made in the design of products and by the manufacturing processes in their
production. It evaluates the potential for safe substitutes for priority uses of toxic chemicals
by identifying and evaluating priority products that contain or use certain priority chemicals
in their production; by identifying the existing substitutes for these priority products; and
determining the technical impediments to the use of safe substitutes for priority products.
Future research needs are also identified and a method is presented for identifying priority
chemicals for substitute evaluation.
This report was submitted in partial fulfillment of Cooperative Agreement
CR #816735-01-0 by the University of Tennessee's Center for Clean Products and Clean
Technologies, under the sponsorship of the U.S. Environmental Protection Agency. This
work covers a period from September 10, 1990 to September 9, 1994, and was completed as
of August, 1994.
IV
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TABLE OF CONTENTS
PART I: PRIORITY CHEMICALS
Chapter Page
INTRODUCTION AND EXECUTIVE SUMMARY ES-1
1. METALS AND METAL COMPOUNDS 1
PHYSICAL PROPERTIES OF THE 33/50 METALS 1
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 2
Cadmium 2
Chromium 3
Lead 3
Mercury 4
Nickel 4
INDUSTRY PROFILE 5
Market Trends 5
Price of the 33/50 Metals and Metal Compounds 6
PRODUCTION PROCESSES 6
Cadmium Production 6
Chromium Production 8
Mercury Production 8
Lead Production 8
Nickel Production 9
ENVIRONMENTAL RELEASES OF THE 33/50 METALS AND
METAL COMPOUNDS 9
Environmental Releases From Production Facilities 9
Distribution of Environmental Releases by Industry Group 9
USES OF THE 33/50 METALS AND METAL COMPOUNDS 14
Battery Manufacture 14
Metal Finishing 14
Pigments 15
2. ORGANIC CHEMICALS 25
PHYSICAL PROPERTIES 25
Aromatic Compounds 25
Ketones 27
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 27
Aromatic Compounds 28
Ketones 29
INDUSTRY PROFILE 29
BTX Market Trends 29
Ketones Market Trends 33
Price of the 33/50 Organic Compounds 34
PRODUCTION PROCESSES 34
BTX Production Processes 34
Ketone Production Processes 38
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ENVIRONMENTAL RELEASES OF THE 33/50 ORGANIC COMPOUNDS 39
Environmental Releases from Production Facilities 39
Distribution of Environmental Releases by Industry Group 42
USES OF THE 33/50 ORGANIC CHEMICALS '.'.'.'.'.'. 42
Plastics and Resins 44
Paints and Coatings 44
3. HALOGENATED ORGANIC COMPOUNDS . . . . 57
PHYSICAL PROPERTIES ] ' 57
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES '.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 59
Dichloromethane 59
Chloroform 60
Carbon Tetrachloride 60
Tetrachloroethylene 61
Trichloroethylene 61
1,1,1-Trichloroethane 61
INDUSTRY PROFILE '.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'." 61
Market Trends 63
Price of the 33/50 Halogenated Compounds 63
PRODUCTION PROCESSES 63
Hydrochlorination of Methanol 64
Direct Chlorination of Methane 64
Hydrocarbon Chlorinolysis 65
Chlorination of Ethylene Dichloride 65
Oxychlorination of Ethylene Dichloride 65
Production of TCA 65
ENVIRONMENTAL RELEASES OF 33/50 HALOGENATED COMPOUNDS ".'.'.'.'. 65
Environmental Releases from Production 66
Distribution of Environmental Releases by Industry Group 66
USES OF THE HALOGENATED ORGANIC COMPOUNDS '.'.'.'.'.'.'.'.'.'.. 69
Fluorocarbon Production 72
Metal and Parts Degreasing 72
Dry Cleaning 72
Consumer Products 72
4 HYDROGEN CYANIDE AND CYANIDE COMPOUNDS 77
PHYSICAL PROPERTIES 77
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 77
INDUSTRY PROFILE '.'.'.'.'.'.'.'. 79
Market Trends 79
Price of Cyanide Compounds 80
PRODUCTION PROCESSES '.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 80
Production of Hydrogen Cyanide 80
Production of Sodium Cyanide 81
ENVIRONMENTAL RELEASES FROM PRODUCTION . . ' . ' . . . . . . . . ..'..' 81
Environmental Releases from Production Facilities 81
Distribution of Environmental Releases by Industry Group 83
USES OF THE 33/50 CYANIDE COMPOUNDS '.'.'.'.'.'.'.'.'.'.]'.'.'. 83
PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
VI
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5. BATTERIES 87
INDUSTRY PROFILE 87
Primary Batteries 87
Secondary Batteries 89
Quantity of 33/50 Metals Used in Batteries 89
Price of Batteries 90
DESIRED PROPERTIES OF BATTERIES '.'.'.'.'. 91
ENVIRONMENTAL RELEASES OF 33/50 METALS FROM PRODUCTION,
USE, AND RECYCLING OF BATTERIES 91
Environmental Releases from Production of the 33/50 Metals
and Metal Compounds 91
Environmental Releases of 33/50 Metals from Battery Manufacturing 92
Environmental Releases of the 33/50 Metals from Battery Recycling 92
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 92
EVALUATION OF SUBSTITUTES 96
Safe Substitutes for Mercury in Carbon-Zinc and Alkaline MnO2 Batteries 96
Safe Substitutes for Mercury in Button Cell Batteries 98
Safe Substitutes for Mercuric Oxide Heavy Duty Batteries 98
Safe Substitutes for Nickel-Cadmium Batteries 98
Safe Substitutes for Lead-Acid Batteries 101
Conclusions 103
6. ELECTROPLATING '.'.'.'.'.'.'.'.'.'.'. 107
INDUSTRY DESCRIPTION '.'.'.'.'.'. 107
Quantity of 33/50 Metals and Cyanides Used in Electroplating 108
Price of 33/50 Metals and Cyanides Used in Electroplating 108
DESIRED PROPERTIES OF 33/50 METALS AND CYANIDES IN
ELECTROPLATING 108
Cadmium 109
Chromium 109
Nickel 109
Cyanide Compounds 110
ELECTROPLATING PROCESS DESCRIPTION '.'.'.'.'. 110
Plating Bath Process 110
Brush Plating 110
Cadmium Plating Baths 111
Chromium Plating Baths Ill
Nickel Plating Baths Ill
ENVIRONMENTAL RELEASES OF 33/50 COMPOUNDS FROM
ELECTROPLATING PROCESSES 112
Environmental Releases from Refining or Production of the
33/50 Metals, Metal Compounds, and Cyanide Compounds 112
Environmental Releases of 33/50 Metals and Cyanides from Electroplating .... 114
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 114
EVALUATION OF SUBSTITUTES 116
Redesigning the Product 116
Alternative Metal Deposition Technologies 117
Using Safer, Less Toxic Metals and Plating Baths 118
Conclusions 124
7. PLASTICS AND RESINS '.'.'.'.'.'.'.'.'.'.'.'.'.'. 129
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INDUSTRY PROFILE ................ .............. 129
Quantity of Polystyrene Used ................ ............ 130
Price of Polystyrene ......... ................. 130
DESIRABLE PROPERTIES OF POLYSTYRENE ......................... no
PROCESSES FOR PRODUCING POLYSTYRENE ........ .'!.'.'.'.'.'.'.'.' ..... 134
Production of Ethylbenzene ..................... .............
Production of Styrene Monomer ....................
Production of Polystyrene ..................
ENVIRONMENTAL RELEASES FROM PRODUCTION OF POLYSTYRENE . . 136
Environmental Releases from Benzene Production .............. 136
Environmental Releases from Styrene Production 135
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES ...'.' .' .' .' '.'.'.''' ...... i36
Ethylbenzene and Styrene ...................... ...........
Polystyrene .................. ................
EVALUATION OF SUBSTITUTES .............. '.'.'.'.'.'.'.'.'.'.'.'. ....... 139
Degradable Plastics Industry .................... ............ '' 140
Starch-Based Degradable Plastics .............. ........... 142
Sugar-Based Degradable Polymers ............. ......... ....... 144
Management of Degradable Polymers .............. ......... 145
Conclusions ........ ............. . Af.
8. PAINTS AND COATINGS ..... ............................... T?
INDUSTRY PROFILE ............... ............ ............... {5}
Quantity of 33/50 Organic Solvents used in Paints and Coatings .... ....... 152
Price of 33/50 Organic Solvents in Paints and Coatings ..........
COMPONENTS OF PAINTS AND COATINGS ....... .'.'.' .............
Pigments ................. ...................
Binders ..................... ™
Solvents ................
DESIRED PROPERTIES OF PAINT AND COATING SOLVENTS .............
COATING PROCESSES ...................... .............
Dip, Flow, Curtain, Roller, and Coil Coating ...... ............... 155
Spray Coating Methods .................
Film Formation ..........
ENVIRONMENTAL RELEASES OF 33/50 ORGANIC SOLVENTS FROM ........
THE PAINTS AND COATINGS INDUSTRY ............... 156
Environmental Releases from Production ........ ...... ........... 155
Environmental Releases from the Paints and Coatings Process ............
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES ............
EVALUATION OF SUBSTITUTES ............. ...................
Product Redesign ................. ..... .................. fen
Water-Borne Paints and Coatings ........... ................ 160
High-Solids Paints and Coatings ......... ........ .............. 162
Powder Coatings ................. ...................
Aqueous Powder Suspensions ........... . . . . . ................ 164
Conclusions .......... ....................... .°7
................................ 165
9. MATERIALS AND PARTS DECREASING
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INDUSTRY PROFILE 169
Quantities of 33/50 Halogenated Solvents Used in Degreasing 170
Price of 33/50 Halogenated Solvents Used in Degreasing 170
DESIRED PROPERTIES OF DEGREASING SOLVENTS 170
DEGREASING PROCESS DESCRIPTION 170
Cold Cleaning 170
Vapor Degreasing 171
Conveyorized Degreasing 171
Hybrid Degreasing Systems 171
ENVIRONMENTAL RELEASES FROM DEGREASING 172
Releases and Transfers from Production and Distribution Facilities 172
Releases and Transfers from the Degreasing Process 172
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 172
EVALUATION OF SAFE SUBSTITUTES FOR THE 33/50
DEGREASING SOLVENTS 173
No-Clean Technologies 173
Aqueous and Semi-Aqueous Solvent Substitutes 174
Non-Aqueous Solvent Substitutes 176
Non-Liquid Technologies 177
Conclusions 177
10. DRY CLEANING 181
INDUSTRY DESCRIPTION 181
Quantity of PCE Used in Dry Cleaning 182
Price of PCE Used in Dry Cleaning 182
DESIRED PROPERTIES OF DRY CLEANING SOLVENTS 182
DRY CLEANING PROCESS DESCRIPTION 183
ENVIRONMENTAL RELEASES OF PCE FROM DRY CLEANING 183
Environmental Releases from Production and Distribution 183
Environmental Releases from Dry Cleaning Facilities 184
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 185
EVALUATION OF SAFE SUBSTITUTES FOR PCE IN DRY CLEANING 187
Reducing the Use of Water-Sensitive Fabrics 187
Alternative Cleaning Processes 187
Solvent Substitutes 189
Conclusions 191
11. PAINT STRIPPING 195
PRODUCT PROFILE 195
Quantity of DCM Used in Paint Stripping 196
Price of DCM Used in Paint Stripping 196
DESIRED PROPERTIES OF CHEMICAL PAINT STRIPPERS 196
PROCESS DESCRIPTIONS 196
Manufacturing of DCM-Based Paint Strippers 196
Consumer or Household Paint Stripping 197
Industrial Paint Stripping 197
ENVIRONMENTAL RELEASES OF DCM FROM PAINT STRIPPING 198
Environmental Releases from Production and Distribution of DCM 198
Environmental Releases of DCM from Paint Stripping 198
HEALTH, SAFETY, AND ENVIRONMENTAL ISSUES 198
EVALUATION OF SAFE SUBSTITUTES FOR DCM PAINT STRIPPERS 200
IX
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Media Blasting Technologies
Chemical Substitutes
Process Modifications ™
Conclusions . .
205
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TABLES
Page
Table 1.1 33/50 Metals Consumption Within the U.S 5
Table 1.2 Prices of 33/50 Metals 7
Table 1.3 Releases and Transfers of 33/50 Metals from the Primary
Non-Ferrous Metals Industry (SIC 3339) 10
Table 1.4 Releases and Transfers of Cadmium from the Primary Zinc
Industry (SIC 3333) 11
Table 1.5 Total Releases and Transfers of 33/50 Metals and Metal Compounds 12
Table 1.6 Top Industries for Total TRI Releases and Transfers of 33/50
Metals and Metal Compounds 13
Table 2.1 Selected Physical Properties of Benzene, Toluene, and Xylene Isomers 26
Table 2.2 Selected Physical Properties of 33/50 Ketones 27
Table 2.3 Supply and Demand of BTX Compounds 30
Table 2.4 Supply and Demand of 33/50 Ketones 32
Table 2.5 Prices of 33/50 Organic Compounds 34
Table 2.6 Production Capacity of BTX Compounds by Process Capacity 37
Table 2.7 Releases and Transfers of BTX Compounds from Petroleum
Refining (SIC 2911) 40
Table 2.8 Releases and Transfers of Ketones from Production Facilities 41
Table 2.9 Total Releases and Transfers of 33/50 Organic Chemicals 42
Table 2.10 Top Industries for Total TRI Releases and Transfers of 33/50
Organic Compounds 43
Table 3.1 Selected Properties of 33/50 Halogenated Compounds 58.
Table 3.2 Supply and Demand of 33/50 Halogenated Compounds 62
Table 3.3 Prices of 33/50 Halogenated Compounds 64
Table 3.4 Releases and Transfers of 33/50 Halogenated Compounds from
Production Facilities 67
Table 3.5 Total Releases and Transfers of 33/50 Halogenated Organic Compounds 69
Table 3.6 Top Industries for Total TRI Releases and Transfers of 33/50
Halogenated Organic Compounds 70
Table 4.1 Selected Properties of Hydrogen Cyanide and Sodium Cyanide 78
Table 4.2 Hydrogen Cyanide Production Capacity 79
Table 4.3 Sodium Cyanide Production Capacity 80
Table 4.4 Prices of Hydrogen Cyanide and Sodium Cyanide 81
Table 4.5 Releases and Transfers of Hydrogen Cyanide and Sodium Cyanide
from Production Facilities 82
Table 4.6 Total Releases and Transfers of 33/50 Cyanides 84
Table 4.7 Top Industries for Total TRI Releases and Transfers of 33/50 Cyanides 84
Table 5.1 Quantity of 33/50 Metals Consumed in Batteries 89
Table 5.2 Yearly Mercury Consumption in Batteries 90
Table 5.3 Price of Batteries 90
Table 5.4 Releases and Transfers of 33/50 Metals and Metal Compounds from
the Storage Batteries Manufacturing Industry (SIC 3691) 93
Table 5.5 Releases and Transfers of 33/50 Metals and Metal Compounds from
the Primary Batteries Manufacturing Industry (SIC 3692) 94
Table 5.6 Releases and Transfers of Lead and Lead Compounds from the
Secondary Lead Smelting Industry (SIC 3341) 95
XI
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Table 5.7 State Legislative Dates for Low Mercury/No Mercury Formulations
for Alkaline and Zinc-Carbon Batteries 97
Table 5.8 State Regulations For Mercuric Oxide Button Cells '.'.'.'.'.'.'.'.'. 99
Table 5.9 Comparison of Rechargeable Battery Chemistries 102
Table 6.1 Prices of Compounds Used in Electrolytic Solutions ' . 109
Table 6.2 Releases and Transfers of 33/50 Chemicals from the Inorganic
Chemical Industry (SIC 2819) 113
Table 6.3 Releases and Transfers of 33/50 Chemicals from the Electroplating
Industry (SIC 3471) U5
Table 6.4 Comparison Between Metallic-Ceramic Coating and Cadmium Plate ........ 119
Table 6.5 Comparison of Non-Cyanide Cadmium Electroplating Baths [] 120
Table 6.6 Metal Parings for Non-Cyanide Immersion Plating Baths ' . . 121
Table 6.7 Chromium Plating Typical Operating Conditions '.'.'.'.'.'.'.'.'.'. 122
Table 6.8 Comparison Between Tin-Cobalt and Decorative Chromium 123
Table 7.1 Polystyrene Resin Production Capacity '.'.'.'.'.'. 131
Table 7.2 Polystyrene Uses in Molding Grade Applications '.'.'.'.'.'.'' 132
Table 7.3 Polystyrene Uses in Extrusion Grade Applications 133
Table 7.4 Polystyrene Uses in Expandable Bead Grade Applications 134
Table 7.5 Price of Polystyrene 134
Table 7.6 Releases and Transfers of Chemicals Used to Produce Polystyrene
from Plastic Materials and Resins Manufacturing (SIC 2821) .... 137
Table 7.7 Producers of Degradable Polymers ' 141
Table 8.1 Estimated Consumption of 33/50 Organic Solvents in Paints
and Coatings .„
Table 8.2 Releases and Transfers of 33/50 Organic Compounds from the Paints
and Allied Products Industry (SIC 2851) 157
Table 10.1 Releases and Transfers of PCE from Specialty Cleaning, Polishes
and Sanitation Goods Producers (SIC 2842) 184
Table 10.2 Requirements of the PCE Dry Cleaning NESHAP ..'.'.'.'.'.'.'.'.'. ig6
Table 10.3 Comparison of Cleaning Methods . . . igg
Table 11.1 Composition of Nonflammable DCM-Based Paint Strippers ' 197
Table 11.2 Releases and Transfers of DCM from the Paints and Allied Products
Industry (SIC 2851) 199
xn
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FIGURES
Page
Figure 1.1 Cadmium 16
Figure 1.2 Chromium 17
Figure 1.3 Lead 18
Figure 1.4 Mercury 19
Figure 1.5 Nickel 20
Figure 2.1 Products Manufactured from Crude Oil 35
Figure 2.2 Production of BTX from Crude Oil 36
Figure 2.3 Benzene to Major Intermediates 45
Figure 2.3.1 Benzene-Styrene Monomer Products 46
Figure 2.3.2 Benzene-Phenol/Acetone Products 47
Figure 2.3.3 Benzene-Adipic Acid/Caprolactam Products 48
Figure 2.3.4 Benzene-Aniline Products 49
Figure 2.4 Toluene 50
Figure 2.5 Xylenes 51
Figure 2.6 Methyl Ethyl Ketone and Methyl Isobutyl Ketone 52
Figure 3.1 Chlorinated Organics 71
Figure 4.1 Cyanides 85
Figure 7.1 Raw Materials for Degradable Polymers 143
Xlll
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ACRONYMS and CHEMICAL ABBREVIATIONS
Ag;,0
Al
APS
ASF or A/ft2
ASTM
atm
BOD
BTX
CAA
Cd
CFG
CFM
C12
CN
CNS
Co
CO2
Cr
Cr(III)
Cr(VI)
CrO3
CTC
CTSA
DBE
DCM
DfE
DMT-PTA
DOE
EDC
EPA
FAA
FDA
gal
g/1
GNP
GSA
HAP
H2Cr04
HCFC
HC1
HCN
Hg
HgS
KOH
LaNi5
Ibs
Ibs/yr
silver oxide
aluminum
aqueous powder suspension
amperes per square foot
American Society of Testing and Materials
atmospheres
biological oxygen demand
benzene, toluene, and xylene
Clean Air Act
cadmium
chlorofluorocarbon
chloroform
chlorine
cyanide (CN-, cyanide moiety)
central nervous system
cobalt
carbon dioxide
chromium
trivalent chromium
hexavalent chromium
chromic trioxide
carbon tetrachloride
Cleaner Technology Substitutes Assessment
dibasic ester
dichloromethane or methylene chloride
Design for the Environment
dimethyl terephthalate and terephthalatic acid
Department of Energy
ethylene dichloride
Environmental Protection Agency
Federal Aviation Association
Food and Drug Administration
gallons
grams per liter
gross national product
General Services Administration
hazardous air pollutant
chromic acid
hydrochlorofluorocarbon
hydrogen chloride
hydrogen cyanide
mercury
mercury sulfide ore, or cinnabar
potassium hydroxide
lanthanum nickel alloy
pounds
pounds per year
xiv
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Li-CF
Li-FeS2
Li-I2
Li-MnO2
Li-SO2
Li-SOCl2
MEK
mg/1
mg/m3
MIBK
m3
Mm
mm
MMA
Mn
MnO2
MSDS
NaCN
NaS
NESHAP
Ni
NiCd
NiFe
NiMH
NiZn
NMP
NPRC
NSPS
OEM
OPPT
OSHA
Pb
PbS
PCE
PEL
PET
iOTW
ppb
ppm
PSES
PVC
RCRA
RON
SIC
SLI
TCA
TCE
lithium-carbon monofluoride
lithium-iron disulfide or lithium-iron pyrite
lithium-iodine
lithium-manganese dioxide
lithium-sulfur dioxide
lithium-thionyl chloride
methyl ethyl ketone
milligrams per liter
milligrams per cubic meter
methyl isobutyl ketone
cubic meter
misch metal
millimeter
methyl methacrylate
manganese
manganese dioxide
material safety data sheets
sodium cyanide
sodium-sulfur
National Emission Standard for Hazardous Air Pollutant
nickel
nickel-cadmium
nickel-iron
nickel-metal hydride
nickel-zinc
n-methyl pyrrolidone
National Polystyrene Recycling Company
New Source Performance Standards
original equipment manufacturing
Office of Pollution Prevention and Toxics
Occupational Safety and Health Administration
lead
lead sulfide ore, or galena
tetrachloroethylene or perchloroethylene
permissible exposure limit
polyethylene terephtalate
poly(hydroxybutyrate valerate)
polylactic acid or polylactace
publicly owned treatment works
parts per billion
parts per million
pretreatment standards for existing sources
polyvinyl chloride
Resource Conservation and Recovery Act
research octane number
standard industrial code
starting, lighting, and ignition
1,1,1-trichloroethane
trichloroethylene
xv
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FRI Toxics Release Inventory
u-s- United States
underground storage tanks
volatile organic compound
degrees Celsius
dollars per pound
xvi
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INTRODUCTION AND
EXECUTIVE SUMMARY
INTRODUCTION
The hazardous waste problem and many of
the persistent air and water pollution problems
are primarily toxic chemical problems.
Widespread use of toxic chemicals in all
segments of industry and commerce has created
the need to deal with burgeoning wastestreams
containing toxic chemicals emitted into the air
and water and buried in the soil. Two decades of
pollution control regulations have not sufficiently
reduced environmental releases of toxic
chemicals to acceptable levels. Nor have
regulations always protected workers from the
effects of toxic chemicals used in the workplace
or consumers from the effects of toxic chemicals
found hi consumer products.
Substitution of products that do not require
the use of toxic chemicals can reduce hazardous
waste generation, mitigate toxic air and water
pollution, and reduce both worker and public
exposure to toxic chemicals.
Substitution of products (and, in some cases,
practices) that do not require the use of toxic
chemicals can reduce hazardous waste
generation, mitigate toxic air and water
pollution, and reduce both worker exposure to
toxic chemicals and public exposure to toxic
products. Furthermore, as many companies
have already discovered, safe substitutes save
money that would otherwise be spent on
environmental controls, penalties, cleanup costs,
and worker health care.
This report presents the results of the first
study to evaluate the possibility of dramatic
reductions in toxic chemical releases by
focussing on safe substitutes for products that
contain or use toxic chemicals in their
manufacturing processes. By identifying priority
products for substitution and evaluating the
feasibility of safe substitutes for those products,
this study provides an important step in the shift
toward prevention of toxic chemical pollution at
the source.
During the time in which this project has been
conducted, the shift toward prevention of toxic
chemical pollution at the source has been taking
ES-1
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INTRODUCTION AND EXECUTIVE SUMMARY
place, often at a pace that would have seemed
impossible a few years ago. Major efforts have
been initiated by the United States Environmental
Protection Agency (EPA) and other federal and
state agencies to explore the use of safe
substitutes for priority toxic chemicals that far
surpass this modest first study in resources and
industry participation. The chlorofluorocarbon
substitutes evaluations initiated by the Clean Air
Act Amendments of 1990, the EPA sponsored
Cleaner Technology Demonstrations for 33/50
Chemicals, and the EPA Design for the
Environment Program are only three examples
of these major efforts.
This report is intended to illustrate that the
generation of hazardous waste and toxic
pollutants is the result of choices made in the
design of products and the processes by which
they are made.
Another shift that has taken place during the
period of this study is the use of the life cycle
concept and the methodology of life cycle
assessment to evaluate the relative environmental
impacts of products. The life cycle concept
includes an assessment of not only the direct
impacts of toxic chemical exposure but other
major impacts, such as global climate change,
acid rain, ozone depletion, and resource
depletion. The life cycle concept and the
methodology of life cycle assessment are
similar to the approach used in this study in
that they look at the whole manufacturing
process for products and not just at the products
themselves. The life cycle concept and the
approach used in this study place the use of
toxic chemicals in the context of whole product
systems in order to illuminate patterns of
materials use and environmental impacts that
are not readily seen when focussing on one
product or one chemical use.
This report is first intended to illustrate that
the generation of hazardous waste and toxic
pollutants is the result of choices made in the
design of products and the processes by which
they are made that require the use of toxic
chemicals. These choices were not made lightly
in most cases. The chemicals chosen that are
now priority pollutants have properties that make
them well suited for their uses. The web of
production of numerous products and materials
that consumers have come to depend upon is
based in large measure on toxic chemicals
discussed in this report that have become
industrial building blocks. These products and
materials include plastics and synthetic fibers,
electronics components and batteries, paints and
coatings, and plated metal materials used in
automobiles and household appliances.
The idea of safe substitutes and tlie research
In this report challenge the necessity of massive
toxic chemical releases while recognizing that
t/iere are no across-the-board solutions and that
each chemical use is unique.
This dependence on hundreds of uses of
building block toxic chemicals has become
so pervasive that their release to the environment
by the millions of pounds is accepted as a
necessity of this industrial economy. The
EPA's 33/50 Program of voluntary reductions
in the releases of priority toxic chemicals was
a positive challenge to this acceptance. The
idea of safe substitutes and the research in this
report also challenge the necessity of massive
toxic chemical releases while recognizing that
there are no across-the-board solutions and that
each chemical use is unique.
ES-2
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A concerted effort to develop safe substitutes
for major uses of priority toxic chemicals,
through product and process redesign, can
reduce hazardous waste generation and toxic
chemical pollution without sacrificing the
functions of goods and services that society has
come to rely upon.
With the relatively modest level of effort of
this exploratory project, existing substitutes for
priority toxic chemicals were identified that can
result in dramatic reductions in the releases of
these toxic chemicals. Many of these are now
coming into wider use. A concerted effort by
manufacturers, with EPA leadership, to develop
safe substitutes for major uses of priority toxic
chemicals, through product and process redesign,
can reduce hazardous waste generation and toxic
chemical pollution without sacrificing the
functions of goods and services that society has
come to rely upon.
OBJECTIVES OF THE PROJECT
The objectives for this study were to:
1) evaluate the potential for safe substitutes
for priority uses of toxic chemicals by:
• identifying priority products that contain or
use certain priority chemicals in their
production;
• identifying and evaluating the existing
substitutes for these priority products; and
• determining technical impediments to the use
of safe substitutes for priority products.
2) Determine the future research needs for
safe substitutes for priority products; and
3) Develop a method for identifying priority
chemicals for substitute evaluation.
APPROACH
The identification of priority products for
substitution starts from the perspective of
priority chemicals. Priority products include
products that either contain priority chemicals
or somehow incorporate them in the
manufacturing process in a way that results in
environmental releases or worker exposure.
By reducing the use of these priority products,
the uses and releases of priority chemicals can
be reduced. The best way to reduce the use
of priority products, and thus, priority
chemicals, is to identify safe substitutes that
effectively perform the same function without
adverse environmental consequences or human
exposure.
Identification of Priority Chemicals
The identification of priority products in
this study focused on products that either
contain or use compounds included in the U.S.
EPA's 33/50 Program. The 33/50 Program
is a voluntary pollution prevention initiative
intended to achieve reductions in pollution in a
relatively short time frame. The program
enlisted companies in important industry sectors
to make voluntary commitments to reduce
reported releases and transfers of 17 priority
chemicals. Participating companies were
asked to develop their own reduction goals
contributing toward national reduction goals of
33 percent by 1992 and 50 percent by 1995.
Reductions are measured against a 1989 baseline
of information reported to EPA under the Toxic
Release Inventory (TRI). EPA is seeking
reduction primarily through pollution prevention
practices which go beyond regulatory
requirements.
ES-3
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INTRODUCTION AND EXECUTIVE SUMMARY
The 33/50 chemicals include the following:
• Metals and Metal Compounds
cadmium
chromium
lead
mercury
nickel
• Organic Chemicals
benzene
toluene
xylenes
methyl ethyl ketone
methyl isobutyl ketone
• Halogenated Organic Chemicals
carbon tetrachloride
chloroform
tetrachloroethylene
dichloromethane (methylene chloride)
1,1,1-trichloroethane
trichloroethylene
• Cyanide Compounds
EPA selected these compounds for the voluntary
pollution prevention initiative based on a number
of factors, including their high production
volume, high releases and off-site transfers of the
chemicals relative to their total production,
oppoitunities for pollution prevention, and their
potential for causing health and environmental
effects.
The Safe Substitutes Project also included a
major task to develop a chemical ranking and
scoring system for the systematic selection of
priority chemicals for substitutes assessments.
This ranking and scoring system was developed
using available data on human health and
environmental toxicity together with data relating
to the potential for exposure. An algorithm was
developed to combine the various endpoints and
exposure potential into an overall hazard
value and ranking for a group of chemicals
from the TRI list and for high-volume
pesticides. The chemical ranking and scoring
system and the results of its application to
this list of chemicals is contained in a separate
report entitled, Chemical Hazard Evaluation
for Management Strategies: A Method for
Ranking and Scoring Chemicals by Potential
Human Health and Environmental Impacts.
Identification of Priority Products
Using the 33/50 chemicals as the priority
chemicals for this project, a list of priority
products was developed by determining trie most
important uses of each chemical and the products
that either incorporate it into their formulations
or rely upon it heavily in the manufacturing
process. Priority products for each chemical
represent those significant uses that also result in
significant environmental releases of the priority
chemical.
A useful tool was developed for identifying
priority products for each of the priority
chemicals: the chemical-use tree diagram.
Chemical-use tree diagrams show the step-wise
progression of the use of a chemical, from the
raw material stage through the final consumer
or industrial use of the chemical or use of
consumer products manufactured from the
chemical. Figure ES.l is the chemical-use tree
diagram developed for cyanides, which is an
example of the chemical-use trees that are
contained in this report that were developed for
each of the priority chemicals. The numbers
along the branches of the use tree are weight
fractions of the usage of the chemical or product
in the first box to produce the chemical or
product in the second box. In this particular
case, reliable data were not available to quantify
the uses along some branches of the use tree,
since such data is difficult to obtain from the
published literature.
ES-4
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ADIPONITRILE FOR NYLON 6/6
FIBERS AND PLASTICS (SEE FIG. 2.3.3)
METHYL METHACRYLATE
.24
.21
.18
.10
.08
SODIUM CYANIDE
ACRYLIC SHEET
MOLDING POWDERS & RESINS
SURFACE COATINGS
IMPACT MODIFIERS
FOR PVC
EMULSION POLYMERS
CYANURIC CHLORIDE
CHELATING AGENTS
(EDTA, NTA)
EXTRACTION OF PRECIOUS METALS
METAL FINISHING
DYES & PIGMENTS
NOTE: Reliable data were not available to
estimate weight fractions along some branches
of the chemical-use tree.
TRIAZINE
HERBICIDES
(E.G., ATRAZINE)
OPTICAL BRIGHTENERS
FOR DETERGENTS
REACTIVE DYES AND
ANTHRAQUINONE DYES
FIGURE ES.l CYANIDE CHEMICAL-USE TREE
As the priority products for each of the 33/50
chemicals were identified, it became apparent
that some of the priority products clustered into a
few overall use clusters involving the use of
more than one of the priority chemicals. These
included, for example, paints and coatings,
which require use of the 33/50 organic chemicals
and some of the 33/50 metals and also result in
the use of paint strippers utilizing one of the
33/50 halogenated organics. Four of the priority
product classes selected for substitutes evaluation
represented use clusters involving more than one
of the 33/50 chemicals. Figure ES.2 illustrates
the use clusters among the priority products
chosen for substitutes evaluation, as well as
priority products that were selected to represent
major uses of single chemicals from the 33/50
list.
Priority products were also identified for
which substitutes assessments were not
performed. These priority products can be the
subject of future research. This report is
intended to demonstrate the concept and
methodology of chemical use evaluation and
substitutes assessment for a limited number of
priority products.
ES-5
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INTRODUCTION AND EXECUTIVE SUMMARY
Metal
Finishing
Plastics and
Resins
Paints and
Coatings
FIGURE ES.2 PRIORITY PRODUCTS OF 33/50 CHEMICALS
There are three ways of reducing toxic
chemical releases by focussing on products:
redesigning products to reduce or eliminate
toxic chemical components; replacing products
that contain or rely upon toxic chemicals with
different products that do not; and substituting
chemicals or redesigning manufacturing
processes to reduce or eliminate the use of toxic
chemicals to manufacture the products.
Identification and Evaluation of Existing
Substitutes for Priority Products
This report contains an identification and
preliminary evaluation of existing substitutes for
the priority products selected for assessment.
There are basically three ways of reducing toxic
chemical releases by focussing on products:
• redesigning products to reduce or eliminate
toxic chemical components;
ES-6
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• replacing products that contain or rely upon
toxic chemicals with different products that do
not; and
• substituting chemicals or redesigning
manufacturing processes to reduce or
eliminate the use of toxic chemicals used to
manufacture the products.
The substitutes assessments were based on
literature reviews, vendor contacts, and user
contacts and did not include demonstration of the
substitutes or verification of their performance
through independent testing. The evaluations of
the substitutes discuss the degree to which they
have been developed, demonstrated, and
commercialized.
First, literature was reviewed to determine the
specific properties or functions for which each
priority product was developed. Where
necessary, vendors arid users of priority products
were contacted to determine particular reasons
why each priority product is used. Literature
was then reviewed to identify existing substitutes
for each priority product and to determine as
much as possible about the efficacy of the
substitutes, their impact on reducing hazardous
waste generation and chemical releases,
impediments to substitutions and their economics
as compared to the original products. Vendors
and users of substitutes were also interviewed to
obtain current information on safe substitutes and
other information not available in literature.
Finally, experts were enlisted in certain product
areas to evaluate substitutes.
ORGANIZATION OF THIS REPORT
This report is organized into two parts. Part I
contains the discussion of each of the priority
chemicals and the selection of priority products
for substitutes assessments. It is divided into
four chapters for each of the four classes of
33/50 chemicals: organic chemicals; halogenated
organic chemicals; metals; and cyanide
compounds. For each of the chemicals, the
discussion includes the physical properties, health
and environmental issues, an industry profile on
manufacturers, the supply and demand, the
price, the production processes, environmental
releases and transfers from the TRI, and an
analysis of uses. A chemical-use tree is also
presented for each of the chemicals.
Part II of the report contains the discussion of
each of the priority product groups or use
clusters for which substitutes assessments were
performed in this study. This discussion includes
an industry profile, the quantity of 33/50
chemicals used in the manufacturing of the
product, the important properties of the product
which result in the use of 33/50 chemicals, the
environmental releases and transfers of 33/50
chemicals during the production of the product,
and a focussed discussion of health, safety and
environmental issues related to the product.
Part II of the report also contains an
evaluation of safe substitutes for each priority
product group or use cluster. These substitutes
span the gamut from simple product
replacements (e.g., use of reusable cups to
replace polystyrene disposables); to product
redesign (e.g., substitution of biopolymers for
polystyrene foam packaging); to substitutions for
toxic chemicals in manufacturing processes (e.g.,
use of aqueous parts cleaning solutions in
electronics manufacturing).
RESULTS OF THE RESEARCH
Following is a brief summary of the results of
the research.
Priority Chemicals
Metals and Metal Compounds. The 33/50
metals and metal compounds studied in this
project included:
ES-7
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INTRODUCTION AND EXECUTIVE SUMMARY
cadmium and compounds;
chromium and compounds;
lead and compounds;
mercury and compounds; and
nickel and compounds.
The amounts of these metals consumed in the
United States (U.S.) in 1992 is presented in
Table ES.l.
TABLE ES.l
33/50 METALS DEMAND IN THE U.S.
IN 1992
Metal
Cadmium
Chromium
Lead
Mercury
Nickel
Amount Consumed
(1992)
(million pounds)
8.20
692.60
2,672.60
1.36
261.40
These metals are released into the
environment during extraction, smelting and
refining, use in manufacturing, and in disposal of
products containing them. The primary metals
industry released more than 43 million pounds of
the 33/50 metals and their compounds to the
environment in 1991, nearly 42 percent of total
releases of these metals and compounds. The
chemical and allied products industry contributed
about 24 million pounds, about 23 percent of the
total releases, most of which were chromium
compounds. Other industries that contributed
significantly were fabricated metals and the
electrical industry.
Table ES.2 shows the total releases and
transfers for each of these metals and
compounds. Throughout the report the quantities
of releases and transfers do not include transfers
to recycling and energy recovery facilities,
consistent with EPA's policy on reporting TRI
data.
TABLE ES.2
TOTAL RELEASES AND TRANSFERS OF
33/50 METALS AND COMPOUNDS IN 1991
Metals and
Compounds
Cadmium
Chromium
Lead
Mercury
Nickel
TOTAL
Environmental
Releases and
Transfers
(million pounds)
2.04
48.87
39.75
0.22
12.94
103.82
Although there are more significant uses of
some of the individual metals, major uses of the
33/50 metals throughout industry are found in
three broad use clusters: batteries (cadmium,
lead, mercury, nickel); electroplating of metals
(cadmium, chromium, nickel); and pigments for
paints, plastics, and inks (cadmium, chromium,
and lead). Batteries and electroplating were
selected for substitutes assessments as the
largest overall end-uses of the 33/50 metals.
Cyanides, another class of 33/50 chemicals, are
also widely used in electroplating.
Organic Chemicals. The 33/50 organic
chemicals studied were:
benzene;
toluene;
xylenes;
methyl ethyl ketone; and
methyl isobutyl ketone.
ES-8
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The amounts of these chemicals produced in
the U.S. in 1992 are presented in Table ES.3.
TABLE ES.3
DEMAND FOR THE 33/50 ORGANIC
CHEMICALS IN 1992
Chemical
Benzene
Toluene
Xylenes
MEK
MIBK
Demand (1992)
(million pounds)
13,790
13,650s1
14,040s
490
175
Capacity data for 1992. Demand data not available.
The first three organic chemicals, benzene,
toluene, and xylenes (BTX), are produced
primarily from petroleum. Petrochemical
feedstock, which is used to produce BTX
and other chemicals, comprises only about
three percent by volume of the products of crude
oil. The two ketones, MEK and MIBK, are
produced from sec-butyl alcohol and acetone,
respectively.
Environmental releases of the 33/50 organic
chemicals occur during the refining of
petroleum, in the production of the chemicals
themselves, and in their distribution and use
in manufacturing chemical intermediates and
final products. These chemicals may also
be incorporated in products from which
they are ultimately released to the environment.
In the TRI, which covers only releases of the
chemicals from manufacturing industries, the
chemicals and allied products industries reported
the greatest amount of releases and transfers of
the 33/50 organic chemicals in 1991, 95.5
million pounds or about 18 percent of the total,
with toluene and xylene releases predominating.
Transportation, rubber and plastic products, and
industries reporting multiple SIC Codes also had
a significant percentage of the total releases.
Table ES.4 shows the total releases and
transfers of the 33/50 organics.
TABLE ES.4
TOTAL RELEASES AND TRANSFERS OF
THE 33/50 ORGANIC CHEMICALS IN 1991
Chemical
Benzene
Toluene
Xylenes
MEK
MIBK
TOTAL
Releases and
Transfers
(million pounds)
20.86
223.50
146.70
114.90
30.80
536.76
Benzene, toluene, and xylenes are basic
building block chemicals that are widely used in
the manufacture of many products. The major
uses of these compounds cluster in two broad use
clusters: plastics and resins precursors (benzene,
toluene, xylenes) and paints and coatings solvents
(toluene, xylenes, MEK, MIBK). Two other
33/50 chemicals, cyanides and dichloromethane,
are also used to manufacture plastics and resins.
Metals on the 33/50 list are used as pigments in
plastics and in paints, and another 33/50
halogenated organic chemical, dichloromethane,
is used in paint stripping. The substitutes
assessments for this class of 33/50 compounds
focussed on a particular plastic, polystyrene,
and on the use of the chemicals as paints and
coatings solvents.
Halogenated Organic Compounds. The
33/50 halogenated organic compounds studied in
this project were:
ES-9
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INTRODUCTION AND EXECUTIVE SUMMARY
dichloromethane (methylene chloride);
chloroform;
carbon tetrachloride;
perchloroethylene;
trichloroethylene; and
1,1,1-trichloroethane.
The U.S. demand for these chemicals in 1992
is shown in Table ES.5.
TABLE ES.5
U.S. DEMAND FOR 33/50 HALOGENATED
ORGANIC CHEMICALS IN 1992
Chemical
Dichloromethane
Chloroform
Carbon tetrachloride
Perchloroethylene
Trichloroethylene
1,1,1 -Trichloroethane
U.S. Demand
(1992)
(million pounds)
390
485
250
250
145
600
manufacturing, and in some cases as a result of
their presence in consumer products. In the
1991 TRI, the largest source of environmental
releases and transfers was the chemicals and
allied products industries, with nearly 16 percent
of the releases, mostly dichloromethane. The
next largest sources were the rubber and plastic
products industry (14.5 percent), the
transportation industry (12 percent), fabricated
metals industry (10 percent), and electrical
industry (8 percent), which use halogenated
solvents for degreasing. The major source of
chloroform releases is the pulp and paper
industry, which creates chloroform as a
byproduct of the chlorine or hypochlorite
bleaching of wood pulp.
The releases from certain uses of the 33/50
halogenated organics are not reported at all in the
TRI. These include the releases of
perchloroethylene from dry cleaning and the
releases of dichloromethane from the use of paint
strippers sold as consumer products.
Table ES.6 presents the total environmental
releases and transfers of the 33/50 halogenated
organics from the 1991 TRI.
The production of these halogenated solvents
is very interrelated, and also related to the
production of chlorofluorocarbons.
Dichloromethane and chloroform are co-
products, as are carbon tetrachloride and
perchloroethylene by one process, and
trichloroethylene and perchloroethylene by
another. The ratio of the co-products in each
case can be adjusted by the manufacturer
depending upon the demand for the ultimate
products produced. Chloroform, carbon
tetrachloride, and perchloroethylene have each
had major usage as intermediates in the
production of chlorofluorocarbons.
Environmental releases of the 33/50
halogenated organics occur during the production
of the compounds, in their uses in
TABLE ES.6
TOTAL RELEASES AND TRANSFERS OF
THE 33/50 HALOGENATED ORGANICS IN
1991
Chemical
Dichloromethane
Chloroform
Carbon tetrachloride
Perchloroethylene
Trichloroethylene
1,1,1 -Trichloroethane
TOTAL
Total Releases
and Transfers
(million pounds)
94.8
22.6
2.6
20.8
38.0
146.0
324.8
ES-10
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The single largest use (approximately 37
percent) of the 33/50 halogenated organic
compounds is as a precursor in the
manufacturing of chlorofluorocarbons (CFCs)
and hydrochlorofluorocarbons (HCFCs). Due to
regulatory phase-outs of carbon tetrachloride and
CFCs at the end of 1995, this use is declining
rapidly for carbon tetrachloride, which is the
precursor for CFC-11 and CFC-12, and for
perchloroethylene, which is the precursor for
CFC-113. The use of chloroform to produce
HCFC-22, on the other hand, will continue
beyond 1995. EPA proposes phasing-out the
HCFCs with the highest depletion potential by
2005, with exceptions made for the servicing of
equipment until 2015.
The second largest use of these chemicals
(approximately 24 percent) is for materials and
parts degreasing in several industries, including
the transportation industry, the fabricated metals
industry, and the electrical industry.
Trichloroethylene, 1,1,1-trichloroethane, and to
a lesser extent, dichloromethane and
perchloroethylene, have been used for cleaning
machined parts and electrical components.
Production of 1,1,1 -trichloroethane is being
phased-out by the end of 1995.
Other major uses include dry cleaning for
perchloroethylene, resulting in 50 percent of the
demand for this chemical, and paint stripping for
dichloromethane, resulting in about 31 percent of
the demand for this chemical. Commercial paint
strippers sold to consumers and paint strippers
used in manufacturing applications both contain
dichloromethane.
The uses of 33/50 halogenated organics are
found in clusters with other 33/50 chemicals.
The use of halogenated organics in parts
degreasing is related to the use of toxic metals
and cyanides in electroplating and the use of
organic solvents in paints and coatings, since
machined parts are typically cleaned prior to
electroplating or application of coatings. The use
of halogenated organics as paint strippers is also
related to the use of organic solvents in paints
and coatings, since certain coatings applications
necessitate the use of paint stripping.
The substitutes assessments in this study
focussed on the use of 33/50 halogenated
organics in parts degreasing, in dry cleaning
of fabrics, and in paint stripping. Although the
use as precursors for chlorofluorocarbon
production was the greatest use of these
compounds, the assessment of substitutes for this
use was not performed in this study because the
development of substitutes has received a
tremendous amount of attention as a result of the
phase-outs of CFCs.
Cyanides. The fourth class of 33/50
compounds included in this report is cyanide
compounds, including hydrogen cyanide and
cyanide salts. The most commonly used cyanide
salt is sodium cyanide.
The U.S. production capacity for hydrogen
cyanide and sodium cyanide in 1993 and 1991,
respectively, is shown in Table ES.7. Hydrogen
cyanide production is reported to be near
capacity, but sodium cyanide production is
estimated to be about 55 to 70 percent of
capacity. Hydrogen cyanide is most commonly
produced by reaction of methane, ammonia, and
air (oxygen). Sodium cyanide is produced by
neutralization of hydrogen cyanide with sodium
hydroxide.
TABLE ES.7
U.S. PRODUCTION CAPACITY FOR
CYANIDES
Chemical
Hydrogen cyanide
Sodium cyanide
Production Capacity3
(million pounds)
1,560(1993)
500(1991)
a Demand data not available.
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INTRODUCTION AND EXECUTIVE SUMMARY
Environmental releases of the cyanide
compounds occur during the production of the
compounds, during their use as intermediates in
the manufacturing of chemicals and polymers,
and for sodium cyanide, during its uses in metal
finishing and in gold and silver mining. In the
1991 TRI, the chemicals and allied products
industry contributed nearly 78 percent of the
releases of hydrogen cyanide and cyanide
compounds, with facilities that produce hydrogen
cyanide accounting for 21 percent of the
hydrogen cyanide releases from this industry
sector. The primary metals industry (9 percent)
were also significant contributors of cyanide
compound releases.
Table ES.8 presents the environmental
releases and transfers from the 1991 TRI for
hydrogen cyanide and cyanide compounds.
TABLE ES.8
ENVIRONMENTAL RELEASES AND
TRANSFERS OF HYDROGEN CYANIDE
AND CYANIDE COMPOUNDS IN 1991
Chemical
Hydrogen cyanide
Cyanide compounds
TOTAL
Total Releases and
Transfers
(million pounds)
2.2
5.6
7.8
The major uses of hydrogen cyanide are the
manufacture of intermediates used in the
production of nylon and acrylic polymers and the
manufacture of sodium cyanide. Sodium cyanide
is used extensively for the extraction of gold and
silver from low grade ores in mining, and for
electroplating of gold, silver, copper, zinc,
brass, and cadmium.
Some of these major uses of hydrogen
cyanide and sodium cyanide are found in use
clusters with other 33/50 chemicals. The
production of nylon and acrylic polymers is
also a major use of benzene, a 33/50 organic
compound. Electroplating is an important use
cluster for the 33/50 metals (e.g., cadmium),
and the use of electroplating often requires
parts cleaning with some of the 33/50
halogenated organic compounds (e.g.,
trichloroethylene, 1,1,1-trichloroethane). The
substitutes assessment for cyanides in this
study focussed on the use of sodium cyanide
in electroplating.
SUBSTITUTE ASSESSMENTS FOR
PRIORITY PRODUCTS
Batteries
Substantial progress has been made in the
design and manufacture of batteries that reduce
releases of 33/50 metals, with the exception of
lead-acid automotive batteries.
Substantial progress has been made in the
design and manufacture of batteries that reduce
releases of 33/50 metals. In addition to the
development of new types of rechargeable
batteries, which reduce overall battery
consumption and disposal, successful substitutes
have been developed for the mercury and
cadmium used in batteries.
Low-Mercury and Mercury-Free Batteries.
Low-mercury and mercury-free batteries are
now available commercially in advance of
regulatory deadlines for reductions of mercury
content in zinc-carbon cells and in alkaline
batteries. Mercury in button cell batteries is
being eliminated with the development of zinc-air
cells. In addition to reducing releases of
mercury from smelting, refining and battery
manufacturing, the development of low-mercury
and mercury-free batteries should eliminate
batteries as one of the largest sources of mercury
in the nation's household wastestream.
ES-12
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Nickel-Metal Hydride and Lithium
Batteries. Nickel-metal hydride and lithium
batteries have been introduced as alternatives to
batteries employing a cadmium electrode.
Nickel-metal hydride batteries have demonstrated
some performance advantages over nickel-
cadmium batteries. Although nickel-metal
hydride batteries still contain nickel, a 33/50
metal, rechargeable lithium batteries eliminate its
use. The lithium battery will not be without
potential health and environmental effects,
however, as these batteries contain small
amounts of arsenic.
Lead-Acid Batteries. Although lead-acid
batteries contribute a significantly greater amount
of environmental releases and transfers during
their manufacture, use and disposal than other
types of batteries, development of safe substitutes
for lead-acid batteries has not been as successful.
Potentially viable substitutes for lead-acid
batteries that are currently being evaluated
include nickel-zinc batteries, nickel-iron
batteries, and sodium-sulfur batteries. These
batteries have performance or cost disadvantages
that may prevent their wide use, or they may
present other potential health, safety and
environmental hazards that outweigh those of
lead-acid batteries.
Electroplating
Substitutes are available to reduce the use of
the toxic 33/50 metals and cyanides in many
applications through product redesign to
eliminate electroplating, through alternative
metal deposition techniques, and through new
plating baths.
The complexity of electroplating operations
and the various plating baths used in
electroplating make it difficult to identify across-
the-board substitutes. Substitutes are available,
however, to reduce the use of the 33/50 metals
and cyanides in many applications.
Product redesign to eliminate the use of
electroplating is possible in many cases and can
be the best environmental option, since it
eliminates the use of both the metal and the
plating bath. The printed wiring board industry,
for example, has replaced the cadmium-plated
steel chassis with boards made from resinous
material to eliminate electroplating. Decorative
electroplating is also being replaced in some
industries by paints and coatings. Of course,
paints and coatings have their 33/50 releases and
environmental impacts as well.
Metal deposition methods that do not use a
plating bath are also available. These include
flame and plasma spraying, mechanical plating,
and vacuum metalizing. These methods
eliminate the hazardous plating bath, but not the
use of the toxic metal. One drawback to the
alternative metal deposition methods is that metal
overspray from spraying methods or turnings
from remachining thick coatings may actually
increase the consumption of the toxic metals and
increase occupational hazards.
Finally, substitutes for the 33/50 metals and
for cyanide in plating baths do exist. Zinc,
tin-zinc, tin-cobalt, and other alloys have proven
to be effective substitutes for cadmium and
chromium in decorative and some functional
applications. Trivalent chromium has also been
demonstrated to be an effective replacement for
more toxic hexavalent chromium in some
applications. Several non-cyanide plating baths
have been developed, including sulfate baths for
gold plating and electroless plating, which
eliminates both the cyanide bath and the use of
electricity.
Plastics and Resins: Polystyrene Packaging
and Disposables
Biologically derived polymers, based upon
starch or lactic acid, are available for a number
of applications as replacements for polystyrene.
ES-13
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INTRODUCTION AND EXECUTIVE SUMMARY
The substitutes assessment for plastics and
resins tbcussed on polystyrene packaging and
disposables as one of the largest uses of the
benzene produced from petrochemical feedstock.
Alternatives not only eliminate the releases of
benzene and other toxics from production, but
also reduce the burden on land-based disposal
facilities. The most obvious substitutes consist of
eliminating unnecessary packaging and using
reusable products instead of throwaways.
Disposable paper products have been substituted
for polystyrene in some uses, but paper products
have their own set of environmental impacts,
including the release of 33/50 chemicals (e.g.,
chloroform).
Biologically derived polymers, based upon
starch or lactic acid, are also available for a
number of applications as replacements for
polystyrene. Not only do biologically derived
polymers reduce the use and releases of 33/50
organic chemicals, they also are readily
degradable, if properly managed. A more
complete analysis of the impacts of these
polymers on sewage treatment plants or compost
operations, however, needs to be performed.
Paints and Coatings
There has been great progress in the
development of paints and coatings that reduce
the use of 33/50 organic chemicals, including
powder coatings and water dispersible coatings.
There has been great progress in the
development of paints and coatings that reduce
the use of 33/50 organic chemicals, such as
toluene, xylenes, methyl ethyl ketone, and
methyl isobutyl ketone, due to regulatory
restrictions on volatile organic compound (VOC)
content. Safe substitutes for solvent-borne paints
are rapidly taking hold within industry and the
trade sales sector. For the industrial sector,
powder coatings appear to offer the best
environmental alternative in reducing releases of
33/50 chemicals. For home use, water
dispersible paints are the best choice, since they
have the lowest organic solvent content of the
water-borne safe substitutes. A no-VOC paint
was recently introduced that sets an unexpected
new benchmark for the industry.
The safe substitutes for high-solvents paints
are not without releases of 33/50 chemicals.
Many of the resins used in these paints (methyl
methacrylate, polyurethane, and styrene-
butadiene, to name a few) are made from 33/50
chemicals. Since variations of these same resins
are also used in high-solvent paints, the
substitutes clearly result in reductions in releases.
Further research and development should be
encouraged to develop substitutes that, for
example, meet appearance requirements of the
automobile industry or that meet shelf-life
requirements for household paints. Strong
interest from industrial paint users and
consumers is providing impetus for paint
manufacturers to increase their research in these
areas.
Materials and Parts Degreasing
Substantial progress has been made in the
use of safe substitutes for the 33/50 halogenated
organic cleaning solvents. The no-clean
alternative is the preferable substitute for
halogenated organic solvents, with aqueous and
semi-aqueous cleaners being used in many
applications.
Substantial progress has been made in the use
of safe substitutes for the 33/50 halogenated
organic cleaning solvents. Examples of
industries that are switching to safer substitutes
range from the printed wiring board industry, to
the automotive parts industry, to portions of the
U.S. Department of Energy Nuclear Weapons
Complex.
ES-14
-------
The no-clean alternative is the preferable
substitute for halogenated organic solvents.
Eliminating the cleaning process altogether
avoids some of the potential environmental
drawbacks of the aqueous and semi-aqueous
cleaner substitutes, discussed below. Redefining
unnecessarily stringent cleanliness specifications,
eliminating the step which soils the part, or
changing the nature of the soil to eliminate the
need for cleaning are possible ways to implement
the no-clean alternative.
Aqueous and semi-aqueous cleaners have the
broadest range of application as safe substitutes
for the 33/50 halogenated organic cleaning
solvents, although they have some disadvantages.
Some of these substitutes are flammable,
corrosive, or have limited or no toxiciry data. In
addition, switching to aqueous or semi-aqueous
cleaners generally requires additional equipment,
multiple cleaning and rinsing steps, and drying,
depending on the cleaning level currently being
attained in solvent-based cleaning processes.
Substitutes typically require process and facility
testing in order to determine optimum cleaning
chemistries and equipment.
Dry Cleaning
There are three basic approaches that can
successfully reduce the use of perchloroethylene
in dry cleaning of fabrics and garments;
reducing the use of water sensitive fabrics;
modification of the professional dry cleaning
process; and substituting petroleum solvents for
perchloroethylene.
There are three basic approaches that can
successfully reduce the use of perchloroethylene
in dry cleaning of fabrics and garments. The
first is reducing the use of water sensitive fabrics
and garments that require dry cleaning. Second
is the modification of the professional dry
cleaning process to eliminate or reduce the use of
organic solvents. One process that is currently
being demonstrated with EPA participation is an
aqueous cleaning process using soaps made from
natural oils, hand spot cleaning to remove oily
stains, and steam to remove bacteria and odors.
Finally, petroleum solvents can be used as
substitutes for perchloroethylene. They currently
have approximately 10 to 12 percent of the dry
cleaning market, primarily for leather and suede
cleaning, but have the major drawback of
flammability. In fact, perchloroethylene was
originally considered a safe substitute for
petroleum solvents used in dry cleaning.
Paint Stripping
Media blasting meUiods have been developed
that are safe, effective substitutes for
dichloromethane (metliyletie chloride) paint
stripping in the industrial sector, and less
volatile substitute chemicals are available in the
consumer sector.
Several media blasting methods have been
developed that are safe, effective substitutes for
dichloromethane (methylene chloride) paint
stripping in the industrial sector. These methods
are less viable for the consumer, since they
typically require expensive equipment. Of the
media blasting methods described in this report,
the plastic and starch-based methods appear to
be gaining the most widespread acceptance.
Still, selecting between the various methods
requires an evaluation of their environmental
tradeoffs.
Plastic media blasting employs polymers
made from synthetic organic chemicals that may
cause health and environmental effects during
their production, but this method does not
generate wastewater contaminated with paint
particles during the paint stripping process.
ES-15
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INTRODUCTION AND EXECUTIVE SUMMARY
Starch-based media blasting generates
wastewater that may be contaminated with toxic
metal paint pigments, requiring treatment before
release to the environment. More evaluation of
the life cycle environmental impacts of these
alternatives is necessary.
Substitute chemicals for the dichloromethane-
based paint strippers for the consumer market
are the most viable alternatives since they do not
require costly equipment. A number of
chemicals have been used or proposed for use as
substitutes, including n-methyl pyrrolidone
(NMP), dibasic esters (DDEs), paint thinners,
and other solvents (e.g., alkyl acetate, diacetone
alcohol, and glycol ethers). These chemical
substitutes have generally not proven to be as
effective in paint stripping as dichloromethane,
especially on aged paint.
The less volatile alternative chemical stripping
formulations, such as NMP and DBEs, may
offer a health and environmental advantage, at
least because there is less potential for exposure
via inhalation and less potential for air releases.
The toxicity of these substitutes needs to be
better defined.
ES-16
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CHAPTER 1
METALS AND METAL COMPOUNDS
Five of the seventeen 33/50 chemicals fall
within the chemical class of metals and metal
compounds. These are cadmium and cadmium
compounds, chromium and chromium
compounds, lead and lead compounds, mercury
and mercury compounds, and nickel and nickel
compounds.
The 33/50 metals are elements that exist
naturally in trace amounts. The commercial
production (extraction and purification), use, and
disposal, however, can cause their elevated,
sometimes toxic concentrations in the
environment. This chapter presents the physical
properties of the 33/50 metals and metal
compounds; health, safety, and environmental
issues associated with their production and use;
market trends related to their consumption;
mining, smelting and refining processes;
environmental releases from use and production
and the distribution of environmental releases by
industry group; and products or uses of the 33/50
metals and metal compounds.
PHYSICAL PROPERTIES OF THE 33/50
METALS
Cadmium (Cd) is a soft, silver-white,
malleable metal. It dissolves readily in nitric
acid but slowly in hydrochloric acid and sulfuric
acid. Cadmium is relatively insoluble in all
bases and in water. It is highly corrosion
resistant and stable in air. Cadmium experiences
only a slight loss in luster after an extended
period of time hi air, but when heated in air, it
will turn a yellow to brown color as a thin oxide
layer forms. If heated to volatilization, it burns
with a red-yellow flame to form the poisonous
cadmium oxide.1
Chromium (Cr) is a steel-gray to silver-white
metal that is similar to platinum in luster. The
compounds of chromium display a wide variety
of brilliant colors. Chromium is very hard,
highly acid-resistant, and is only attacked by
hydrochloric, hydrofluoric, or sulfuric acid. It is
resistant to corrosion and oxidation.2
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PARTI; PRIORITY CHEMICALS
Lead (Pb) is one of the oldest metals to be
used by people and the first metal to be obtained
from its ore. It is a bluish-white, malleable
metal. A lead carbonate that forms on its surface
matkes it the most corrosion resistant of the
common metals. The properties of lead that
have contributed to its wide-spread use include
its low melting point, ease of casting, high
density, low strength, ease of fabrication, acid
resistance, and chemical stability in air, water,
and soil.3
Mercury (Hg) is a heavy, silver-white metal
that is liquid at room temperature. Mercury has
several unique physical properties that contribute
to its many uses. It has a uniform volume
expansion over its entire liquid range and a high
surface tension which makes it unable to wet and
cling to glass. Mercury also has a tendency to
form alloys (amalgams) with almost all other
metals. Mercury has low resistance to electrical
charge and is thus one of the best electrical
conductors among the metals. Mercury is stable
at ordinary temperatures and does not react with
air, ammonia, carbon dioxide, nitrous oxide, or
oxygen.4
Nickel (Ni) is a light-grey, tough, ductile
metal. It is both corrosion and heat resistant,
and readily fabricated by hot and cold working.
Nickel is slightly soluble in dilute hydrochloric or
suliuric acid, and soluble in dilute nitric acid and
in ammonia.5
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
The 33/50 metals and metal compounds have
similar health, safety, and environmental issues
associated with their use and disposal. Long-
term exposure to the metals may cause organ
damage or, in some cases, cancer. The metals
tend to concentrate in the environment from
human activities, and have a tendency to
bioaccumulate. Issues associated with the use
and production of the 33/50 metals and metal
compounds, including the sources of
environmental releases that may result in adverse
human health or environmental effects, are
discussed briefly below.
All of the 33/50 metals have acute or chronic
health effects. Cadmium, hexavalent
chromium, lead, and nickel are all classified by
EPA as known or suspected carcinogens.
Cadmium
Ingestion or inhalation constitute the two
primary routes of exposure to cadmium. Short-
term exposure to high levels of cadmium causes
nausea, vomiting, abdominal cramps, headaches,
shortness of breath, fever and respiratory
insufficiency. Vomiting can result from water
that has a cadmium concentration as low as 15
parts per million (ppm). Long-term exposure
causes emphysema, other chronic obstructive
pulmonary diseases, kidney damage, anemia,
liver disturbance, and a bone disease called Itai-
itai.6 EPA has classified cadmium as a probable
human carcinogen (Class Bl) based on inhalation
data.7
Exposure to cadmium may occur from the
smelting and refining of zinc, lead, and copper-
bearing ores, the production of batteries, the
synthesis and use of cadmium-containing
pigments, and from its uses in metal plating and
coating, soldering, plastics, ceramic glazes,
alloys, and amalgams.8 The most common
routes of exposure are from food and tobacco
smoke; tobacco may contain one to two ppm
cadmium.9
Combustion of coal and other fossil fuels
releases cadmium into the atmosphere. Disposal
of plastics may also contribute to environmental
contamination since cadmium is used in
stabilizers and pigments. Cadmium
enters surface waters mainly from
manufacturing operations that involve either
cadmium itself or zinc that contains cadmium
as an impurity. Plating operations are major
contributors where spent plating solutions or
rinse waters containing significant amounts of
cadmium are discarded. The production of
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CHAPTER I: METALS AND METAL COMPOUNDS
refined cadmium metal is also a potential
source of cadmium in nearby surface waters.10
Chromium
Chromium has oxidation states ranging from
-2 to +6, but chromium in chemical
compounds most commonly occurs in the
trivalent (+3) and hexavalent (+6) oxidation
states. Trivalent chromium (Cr(III)), which is
also the naturally occurring form, has low
toxicity due to poor membrane permeability
and noncorrosivity. Hexavalent chromium
(Cr(VI)), on the other hand, is highly toxic due
to strong oxidation characteristics and ready
membrane permeability. Thus, the known
harmful effects of chromium are primarily
attributed to hexavalent chromium.
Chromium enters the body by ingestion,
inhalation, and absorption through the skin.
Short-term or acute exposure to chromium may
cause irritant effects such as contact dermatitis
and allergic effects, or oral burn and severe
corneal injury. Dermal absorption results in
damage to renal tubules.11
Effects of long-term exposure to hexavalent
chromium include irritation of the nasal mucous
membrane and the formation of ulcers and
perforations of the nasal septum. All
hexavalent chromium compounds are
mutagenic, and some are classified by EPA as
human carcinogens (Class A).12 Chronic
exposure to hexavalent chromium has been
associated with an increased incidence of lung
cancer.13
Chromium releases into the atmosphere are
largely from the chemical manufacturing
industry and combustion of natural gas, oil, and
coal in which chromium is present as a trace
impurity. Electroplating is a major contributor
of chromium releases via waste water, followed
by the leather-tanning and textiles industries.
Other sources for chromium emissions include
wastewater treatment sludge from the
production of chrome oxide green pigments,
molybdate orange, zinc yellow, and iron blue
pigments. These metal emissions include toxic
hexavalent chromium. Improper land disposal
of municipal incinerator ash and solid waste
from chemical manufacturers may also cause
soil contamination.14
Under normal conditions, Cr(III) and
chromium(O) are relatively unreactive in the
atmosphere. Chromium is associated with
paniculate matter in the air, and is not expected
to exist in gaseous form. Most of the
chromium in surface waters is present in
paniculate form as sediment, Hexavalent
chromium is the major stable form of
chromium in seawater.15
Lead
Routes of lead exposure for humans include
ingestion, inhalation, and absorption. Lead
poisoning affects the nervous, hematologic,
gastrointestinal, and cardiac systems. Chronic
exposure in adults may lead to hypertension
and secondary cardiac effects. In young
children, there may be defects in neurological
development, including learning disabilities,
lowered IQ, and behavioral abnormalities.
High levels of exposure may lead to permanent
mental retardation and even death. In
gastrointestinal systems, lead poisoning alters
central nervous system (CNS) control and
causes anorexia, constipation, and diarrhea.
Toxic levels of lead in the human body can
cause sterility in men, and difficulties with
pregnancies in women.16 Exposure to fumes
from lead furnaces and to dust from drossing
may cause severe lead poisoning.17 EPA has
listed lead as a probable carcinogen (Class B2),
based on positive results in animal studies.18
Lead may enter the environment through all
phases of its production, use, and disposal.
When released to the atmosphere, lead is
generally in dust form or adsorbed to
paniculate matter. Atmospheric lead is
subject to gravitational settling and
transformation to the oxide and carbonate
forms.19
If released to soil, lead is generally retained in
the upper layer of soil. Leaching is not
extensive under normal conditions, though
some plants take up lead. Lead may be
released to surface water in mnoff, wastewater,
or through atmospheric fallout. Lead does not
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PARTI: PRIORITY CHEMICALS
bioconcentrate significantly in fish but will
bioconcentrate in some shellfish such as
mussels.20
Mercury
Most of the organic and inorganic
compounds of mercury are protoplasmic
poisons that can be fatal to humans, animals,
and plants. Human exposure to mercury may
occur by absorption through the skin, ingestion,
and inhalation.
Mercury vapor causes acute damage to the
lungs and chronic damage to the CNS.
Organic mercury compounds can cause toxic
dermatitis and can severely damage the CNS.
Acute and chronic mercury poisoning may
occur when mercury concentrations reach 0.2
mg/100 ml in blood.21
Mercury compounds are mutagenic,
teratogenic, and embryotoxic, but EPA finds
insufficient evidence of their carcinogenicity to
classify them as suspected carcinogens. One
gram of mercuric chloride ingested orally is
thought to be fatal.22
One major source of mercury in the
environment is the disposal of industrial
mercury waste into water where it settles as
sediment. Microorganisms convert elemental
mercury into methyl mercury salt and dimethyl
mercury, which can escape into the
atmosphere. About 50 percent of the volatile
form of mercury is elemental mercury vapor
with a large portion of the remainder being
mercury(II) and methyl mercury. Mercury in
the environment may be revolatilized many
times, with a residence time in the atmosphere
of at least a few days. It can be transported
hundreds of miles in its volatile phase.
Industries like metal smelters or cement
manufacturers may be sources of mercury air
pollution due to mercury contamination within
their products and fuels. Water pollution may
originate in sewage or metal refining
operations, but mostly from chloralkali
manufacturing plants using mercury-based
electrolytic cells. Other sources may be
combustion of fuels containing mercury
impurities and direct releases of various
chemical forms of mercury.23
Mercury bioaccumulates and biomagnifies
up the food chain. Bioconcentration in aquatic
species may be as much as 10,000 times the
concentration in water. Fish accumulate
mercury to very high levels due to rapid
accumulation and slow elimination.24
Nickel
Inhalation and ingestion of soluble salts are
the primary routes of human exposure to
nickel. Early symptoms of nickel fume
inhalation include headache, sore throat,
hoarseness, dizziness, giddiness, and weakness.
Other effects of acute inhalation exposure
include tightness in the chest, coughing,
dyspnea, retrosternal pain, and shortness of
breath. Early symptoms of toxicity after
ingestion include nausea, vomiting, and
diarrhea. An increased incidence of nasal and
lung cancer has been noted in nickel workers.
EPA classifies nickel refinery dust as a human
carcinogen based on human and animal data.25
Nickel soluble salts are not classified as to
carcinogenicity. Contact dermatitis is also a
well recognized allergenic reaction to nickel.26
Releases of nickel are mainly from the
following: nickel ore processing plants;
electroplating; production and use of nickel
catalyst; parts fabricating and welding;
spraying of nickel containing paints; and
manufacturing of nickel-cadmium batteries.
Food-processing methods add to the nickel
levels in foodstuffs through the leaching and
the milling of flour using equipment made of
nickel alloys, and through the nickel catalytic
hydrogenation of fats and oils.27
Nickel exists in the atmosphere as
paniculate matter. Rain transfers airborne
nickel to soils and waters. Soil-borne nickel
may enter water by surface percolation into
groundwater. Physical and chemical
interactions that occur in surface and
groundwater systems determine the fate and
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CHAPTER!: METALS AND METAL COMPOUNDS
transport of nickel in those systems. Nickel
does not undergo biological transformation in
the aquatic environment.28
INDUSTRY PROFILE
Ores containing the 33/50 metals and metal
compounds are mined at a number of locations
in the United States (U.S.) and abroad. Metals
and metal compounds consumed in the U.S. may
be refined from their ores in the U.S. or
imported following the refining process. No
attempt was made in this study to identify the
numerous national or international mining
companies or metal refineries that produce the
33/50 metals and metal compounds. Market
trends in the U.S., consumption, and prices of
the 33/50 metals are presented below.
Market Trends
Table 1.1 presents U.S. consumption data
for the 33/50 metals for the years 1984 to
1992.
U.S. consumption of cadmium fluctuated
somewhat over the years of 1984 through 1992.
Cadmium consumption saw a recent high in
1986 of just over 4,830 short tons, and a recent
low of approximately 3,425 short tons in 1990.
Despite decreases in cadmium use within the
pigments, stabilizers, and coatings industries,
recent increases in the early 1990s are expected
to continue due to the increasing market share
captured by nickel-cadmium (NiCd) batteries
and cadmium-based solar cells.29 Recycling of
NiCd batteries is expected to increase because
of economic and environmental reasons.30
Industry demand for chromium also
fluctuated considerably over the past nine
years. The demand peaked in 1989 at almost
620 short tons, compared to a low in 1983 of
only about 320 short tons. Demand in 1990
was approximately 440 short tons. The
outlook for chromium consumption is strongly
tied to the outlook for stainless steel, since
stainless steel is the largest end-use of
chromium. Worldwide, growth markets
TABLE 1.1 33/50 METALS CONSUMPTION WITHIN THE U.S.
Year
1984
1985
1986
1987
1988
1989
1990
1991
1992
1000 Refined Short Tons Per Year
Lead
1250. la
1239.23
1249.73
1325.9s
1323.9
1483.6
1405.7
1373.8
1336.3
Nickel
136.86"
119.91b
107.06b
130.54b
149.1
140.3
137.3
139.9
130.7
Cadmium
4.13C
4.10"
4.83b
4.60b
3.99
4.52
3.42
3.68
4.10
Mercury
2.07C
1.89"
1.75b
1.59"
1.66d
1.34d
0.79d
0.61d
0.68d
Chromium"
512
508
427.1
557.8
607.0
618.1
443.4
413.5
346.3e
Sources:
Non-Ferrous Metal Data, American Bureau of Metal Statistics, Inc., 1992 (unless otherwise noted)
* Non-Ferrous Metal Data, American Bureau of Metal Statistics, Inc., 1988
b Metal Statistics, 85th ed., American Metal Market, 1993
c Metal Statistics, 78th ed., American Metal Market, 1986
d Mercury Annual Report, 1992, U.S. Department of the Interior, Bureau of Mines
* Chromium Annual Report, 1992, U.S. Department of the Interior, Bureau of Mines
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PARTI; PRIORITY CHEMICALS
for chromium are structural and utilitarian
steels, stainless and heat-resisting steels, and
other metals and alloys. The remaining
chromium markets are considered mature.31
Increasingly stringent environmental
regulations, and reductions and elimination of
mercury in consumer products have caused a
considerable decline in mercury consumption in
tlie last ten years. Chromium use has also
decreased significantly, but U.S. consumption
of the other 33/50 metals has been relatively
stable.
Lead consumption in the U.S. increased from
about 1.25 million short tons in 1986 to a high of
about 1.48 million short tons in 1989.32 The
average annual growth in demand for the period
w;is about three percent. Lead used in storage
batteries, including storage battery oxides,
accounted for nearly 1.09 million short tons of
lead consumption in 1992. Estimates are that the
annual growth in lead demand will probably
decline 0.5 percent to 1.0 percent per year in the
1990s because of increased emphasis on
recycling, as is observed from the data presented
for 1991 and 1992. The use of lead is expected
to be reduced in nongrowth markets such as
solders, paints and coatings, ceramics, containers
or other packaging, and cosmetics.33
Increasingly stringent environmental
regulations caused a considerable decline in
mercury consumption in the 1970s and 1980s.
Average U.S. consumption dropped on average
4.1 percent per year between 1980 and 1986 and
about 1.4 percent per year in the 1970s.
Significant reductions and elimination of mercury
in consumer products have continued this
decrease in mercury use. Projected trends for
the mercury market are toward mercury
elimination from many products, increased
conservation, and recycling because of
environmental considerations.34
Between 1986 and 1990, annual consumption
of nickel fluctuated between a low of about
107,060 short tons in 1986 and a high
of 149,100 short tons in 1988. The reported
U.S. consumption of nickel and nickel
compounds in 1992 was approximately 130,700
short tons. U.S. and world demand for nickel
is driven by the stainless steel industry. The
U.S. Bureau of Mines predicts nickel
consumption will increase three to four percent
annually in the 1990s, based on two long-term
trends in the stainless steel industry: 1) greater
production of stainless steel; and 2) the use of
more nickel in stainless steel products. The
amount of nickel used in electroplating declined
from about 24,200 short tons in 1989 to 14,377
short tons in 1992.35
Price of the 33/50 Metals and Metal
Compounds
Table 1.2 presents the price of the 33/50
metals between 1984 and 1992. Prices of nickel
and cadmium significantly increased in 1988.
The cadmium price increase was attributed to
labor disputes at mining facilities, the flourishing
nickel-cadmium battery industry, and world
demand outstripping production.36 Nickel prices
and consumption rebounded from their lowest
levels in more than 50 years because of stainless
steel demand.37 Other metal prices have been
steady in past years.
PRODUCTION PROCESSES
Metals are typically concentrated from their
ores by mining, smelting, and refining. The
processes for producing the 33/50 metals from
their ores are discussed briefly below.
Cadmium Production
Cadmium is most often found as a trace
element (e.g., sulfide ore, greenockite) in
copper, lead, and zinc ores. Since cadmium
does not occur in high enough concentrations to
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CHAPTER 1: METALS AND METAL COMPOUNDS
TABLE 1.2 PRICES OF 33/50 METALS
Year
1984
1985
1986
1987
1988
1989
1990
1991
1992
U.S. Dollars Per Pound
Lead
0.27
0.20
0.22
0.36
0.37
0.39
0.47
0.33
0.36
Nickel
N/A
3.20"
3.20s1
2.29s
6.31
6.28
4.23
3.87
3.22
Cadmium
1.69b
1.21b
1.25b
1.99b
7.60C
6.28C
3.38C
2.01C
0.91C
Mercury
4.17
4.17
3.20
3.80
4.46
3.91
3.45
1.73
2.55
Chromium*
3.75
3.75
3.75
3.51
3.40
3.55
3.55
3.75
3.75
Sources:
Metal Statistics, 85th ed., American Metal Market, 1993 (unless otherwise noted)
* Non-Ferrous Metal Data, American Bureau of Metal Statistics, Inc., 1989
b Non-Ferrous Metal Data, American Bureau of Metal Statistics, Inc., 1988
c Non-Ferrous Metal Data, American Bureau of Metal Statistics, Inc., 1992
* Electrolytic chromium (99.8 percent on a metallic basis)
N/A: Not Available
economically justify mining for cadmium alone,
it is co-refined with zinc ores (occasionally with
lead and copper ores). Concentrations of
cadmium in zinc ores typically range from 0.05
percent to 0.8 percent (averaging 0.2 percent) on
a weight basis.38 Principal deposits are located in
Scotland, Czechoslovakia, and the U.S.39 The
most important deposits of zinc ores containing
cadmium are stratabound-types in platform
carbonates. In these deposits, the ores are
found in thin zones of replacement
mineralization and are the classic Mississippi
Valley type of deposits.40
Processing begins by grinding the ore until
the sulfide minerals of zinc and cadmium
become individual grains. The grains are then
concentrated by the froth flotation process.
This process uses the addition of certain
reagents to modify the surface properties of the
sulfide particles so that they preferentially
adhere to air bubbles streaming through the
flotation cell. The sulfide compounds are
skimmed off in the froth for further processing
by either the pyrometallurgical or
hydrometallurgical processes.41
In the pyrometallurgical process the sulfide
froth material is roasted and sintered. The zinc
remains in the oven as zinc oxide, while much
of the cadmium impurities are volatilized and
become part of the flue dust. The initial
concentration of cadmium in the flue dust is
about ten percent, but can vary due to
differences in the cadmium concentrations in
the ore. The cadmium concentrations within
the dust can be increased by using a closely
controlled kiln or reverberator furnace.
Leaching of this flue dust with an acid solution
precipitates the cadmium as cadmium
carbonate.
In the hydrometallurgical process
the zinc/cadmium froth is leached with sulfuric
acid. Further steps, including the addition of
zinc dust, reduces the cadmium to form a
metallic sludge of high cadmium
concentration.42
Pure cadmium metal is then obtained from
both the cadmium carbonate precipitate and
metallic sludge by either a leaching or
electrolytic process. The leaching process uses
a sulfuric acid electrolytic bath (25 to 30 g/1 in
-------
PARTI; PRIORITY CHEMICALS
concentration) to dissolve the cadmium
carbonate or metallic sludge. The cadmium is
then oxidized either by blowing air through the
solution or adding manganese dioxide.
Cadmium is then precipitated as a pure metal
sponge by reduction with zinc dust. In the
electrolytic process, once metal impurities are
first removed (e.g., copper, thallium, lead), the
metallic sludge or cadmium carbonate is
dissolved in a sulfuric acid bath (100 g/l in
concentration). Within this sulfuric acid
electrolytic solution is a lead anode and
aluminum sheet cathode. When a current is
applied, the cadmium deposits as a pure metal
sheet on the cathode.43
Chromium Production
Chromite is the only ore that contains
chromium in concentrations of industrial
importance. The U.S. has no chromium
reserves and has limited resources, therefore
chromite ore used in the U.S. is currently
imported.44
Chromite is mined by both surface and
underground methods. Concentrates are
prepared from fines or crushed lower grade
ore. The chromite ore is refined by different
processes depending on the industry that will be
using the chromium product.
The metallurgical industry converts chromite
to chromium metal, chromium alloys, or
chromium additives by electrochemical or
pyrometallurgical processes. The
electrochemical process involves the deposition
of chromium metal by electrolysis of a purified
chromium alum solution. The solution is
prepared by a complex process that begins by
dissolving ferrochromium in sulfuric acid. The
pyrometallurgical process is an aluminothermic
reduction, which reduces pure chromic oxide
with finely divided aluminum metal.
The chemical industry treats chromite by a
hydrometallurgical process. Roasted ground
chromite is mixed with soda ash and lime and
then leached with a weak chromate liquor or
water. Chromite used in the refractory industry
is either purchased to size specifications or is
reduced in size with conventional crushing
equipment. The crushed product is screened into
various ranges of particle sizes.45
Mercury Production
The most important mercury ore is the red
sulfide ore, cinnabar (HgS). Cinnabar is mined
by both surface and underground methods.
After the ore has been broken by conventional
drilling and blasting, it is removed and crushed.
Sometimes this crushed ore is screened to form
a "concentrate" before furnacing.
The mercury ore or mercury concentrate is
refined by heat in retorts or furnaces to liberate
mercury as vapor. The mercury vapor is cooled
in a condensing system to form the liquid metal.
This method of primary mercury refining
produces prime virgin mercury that is more than
99.7 percent pure and acceptable for most
industrial uses. Wastes containing mercury
(spent liquid mercury cathodes, mercury
fluorescent tubes, electrical switches,
thermometer breakage, etc.) can also be
recycled to recover the mercury.46
Lead Production
Lead exists in a variety of ores, but the most
commercially important lead ore is galena
(PbS). Lead is produced from its ore by
mining, milling, smelting, and refining. Lead
is often mined using underground operations.
Once mined, the lead ore is crushed to reduce
its size to about one millimeter in diameter. The
crushed ore is treated by a froth floatation
process to recover the lead sulfide in the froth.
Smelting of this froth concentrate is conducted in
blast furnaces to oxidize the lead and remove the
sulfur as sulfur dioxide. At the refinery stage
many of the impurities are removed. Calcium
and magnesium are added to remove bismuth;
potassium nitrate or caustic are added to remove
arsenic, antimony, and any traces of calcium or
magnesium left from the bismuth process; and
zinc dust is added to remove silver and copper.
The added zinc and impurities of zinc are
removed by vacuum distillation. The refined
lead product is 99.95 to 99.99 percent pure.47
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CHAPTER 1: METALS AND METAL COMPOUNDS
Nickel Production
Lateritic and sulfide ores are the naturally
occurring rock types which contain nickel
sulfide concentrations high enough to
economically justify mining. Nickel sulfides
usually occur as distinct grains within a rock
matrix. Once extracted by open pit or
underground mining methods, this granular
matrix allows for mechanical upgrading by
comminution followed by froth flotation
separation. The product from these processes,
composing of nickel, iron, and copper sulfides,
is mixed with silica flux and enters a
reverberatory furnace where the iron
component of the ore is converted to iron oxide
(discarded as slag). The resulting molten
product, upon cooling, forms nickel and copper
sulfide crystals of high purity.
Crushing of the cooled product and
magnetically separating the metallic fractions
produces a nearly pure nickel sulfide product.
For high grade ores, a nickel sulfide product
stream can also be obtained by magnetic
separation directly following the mining/
comminution process. The nickel sulfide is then
pulverized, smelted to form nickel oxide, and
reduced (by electrolytic refining or leaching) to
form a metallic nickel product.48
The U.S. is a major consumer of nickel and
imports almost all of its supply of Ni ore.
From 1983 to 1986, the production rate of
American mines fell sharply, from 9,600 short
tons in 1984 to 1,200 short tons in 1986. For
the years 1987 and 1988, a negligible amount
of ore was mined in the U.S. The largest
exporter of Ni ore to the U.S. is Canada, with
51 percent of the total American imports in
1987.49
ENVIRONMENTAL RELEASES OF THE
33/50 METALS AND METAL
COMPOUNDS
Environmental releases of the 33/50 metals
and metal compounds occur from their
production, use, and disposal. This section
discusses the releases and transfers from the
mining, smelting, and refining processes, as
well as the distribution of environmental
releases by industry group.
Environmental Releases From Production
Facilities
Environmental releases of the 33/50 metals
and metal compounds resulting from their
production occur from mining through smelting
and refining. Releases from the mining industry
are not required to be reported to TRI, but may
be substantial. Releases and transfers of the
33/50 metals and metal compounds from the
primary' metals industry, which smelts and
refines the ore, are reported in the 1991 TRI
and are summarized in Tables 1.3 and 1.4.
Table 1.3 presents the data for the primary
non-ferrous industry (Standard Industrial Code
[SIC] 3339). Table 1.4 presents the releases
and transfers of cadmium from the primary
zinc industry (SIC 3333). On-site releases to
land constitute the vast majority of the reported
releases and transfers for the primary non-
ferrous and primary zinc industries. No releases
of lead or lead compounds were reported for the
primary lead industry (SIC 3332).x
Lead and chromium are the 33/50 metals
consumed and released to the environment in
the greatest quantities. The primary metals
industry was the largest emitter of lead reported
in the 1991 TRI; the chemical and allied
products industry was the largest emitter of
chromium.
Distribution of Environmental Releases by
Industry Group
Chromium, lead, and nickel and their
compounds were within the top 45 chemicals
for TRI total releases and transfers in 1991.
TRI releases and transfers in 1991 of cadmium
and cadmium compounds ranked number 80,
and of mercury and mercury compounds
ranked number 146. Table 1.5 lists the total
TRI releases and transfers and relative rank of
the 33/50 metal compounds.
-------
PARTI; PRIORITY CHEMICALS
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PARTI: PRIORITY CHEMICALS
TABLE 1.5 TOTAL RELEASES AND TRANSFERS OF 33/50 METALS AND METAL
COMPOUNDS
Chemical
Releases & Transfers
(Ibs/yr)
TRIRank
(combined metal and
compounds)
Cadmium
Cadmium Compounds
Chromium
Chromium Compounds
Lead
Lead Compounds
Mercury
Mercury Compounds
Nickel
Nickel Compounds
1,007,157
1,039,826
8,713,880
40,163,165
11,337,457
28,413,286
180,816
38,958
5,988,929
6,952,629
80
21
24
146
45
TOTAL
103,836,103
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc., Inc.
U.S., EPA, Office of Pollution Prevention and Toxics, 33/50 Program Office
Five industry groups accounted for about 83
percent of the environmental releases and
transfers of 33/50 metals and metal compounds
reported in the 1991 TRI. These industries and
their reported releases are presented in Table
1.6. These data do not include the
environmental releases from disposal of
consumer products that contain these compounds.
The primary metals industry was the largest
contributor to releases and transfers of 33/50
metals and metal compounds in 1991, releasing
a reported 43 million-plus pounds (almost 42
percent of the total) to the environment. Using
the principles of life cycle assessment, these
releases can be associated with the final end
uses of these metals. Releases from the
chemical and allied products industry also
constituted a large fraction (23 percent). These
releases consisted primarily of chromium
compounds.
12
-------
CHAPTER 1; METALS AND METAL COMPOUNDS
TABLE 1.6 TOP INDUSTRIES FOR TOTAL TRI RELEASES AND TRANSFERS OF 33/50
METALS AND METAL COMPOUNDS
Releases and Transfers
(Ibs/yr)
Chemical
Cadmium
Cadmium
Compounds
Chromium
Chromium
Compounds
Lead
Lead
Compounds
Mercury
Mercury
Compounds
Nickel
Nickel
Compounds
TOTAL
RELEASES AND
TRANSFERS
PERCENT OF
TOTAL
RELEASES AND
TRANSFERS
Chemicals
SIC 28
1,923
138,734
91,261
20,968,701
14,067
1,027,493
108,773
36,588
166,448
1,458,472
•
24,012,460
23.13
Electrical
SIC 36
8,119
161,724
41,030
1,128,619
825,454
3, ,060,711
7,799
702
99,960
485,088
5,819,206
5.60
Primary
Metals
SIC 33
26,054
353,288
3,343,326
9,612,072
7,069,553
18,691,522
265
270
1,642,671
, 2,396,671
43,135,692
41.54
Fabricated
Metals
SIC 34
595,223
218,190
1,769,291
1,299,432
633,339
650,668
15
0
1,294,647
689,147
7,149,952
6.89
Multiple
Code
SIC 20-39
347,003
19,106
176,964
143,602
1,061,298
55,981
5
0
442,431
21,020
6,539,718
6.30
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc., Inc.
U.S., EPA, Office of Pollution Prevention and Toxics, 33/50 Program Office
13
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PARTI; PRIORITY CHEMICALS
USES OF THE 33/50 METALS AND METAL
COMPOUNDS
The 33/50 metals and metal compounds are
widely used in metal finishing processes, in
consumer products like batteries and electronic
components, in alloys, and in chemical
manufacturing processes. The uses of the
33/50 metals are illustrated in chemical-use tree
diagrams shown on Figures 1.1 through 1.5.
Figure 1.1 presents the uses of cadmium.51
Figure 1.2 presents the uses of chromium.52
Figure 1.3 presents the uses of lead.53 Figure
1.4 presents the uses of mercury54. Figure 1.5
presents the uses of nickel.55
The numbers along each branch of the
chemical-use tree are weight fractions of the
usage of the intermediate or product in the first
box to produce the intermediate or product in
the second box. For example, in Figure 1.2,
18 percent of the chromium produced is used to
manufacture chemicals; 90 percent of the
chromium chemical products are sodium
bichromate; 55 percent of the sodium
bichromate is used to manufacture chromic
acid. Chromic acid is used to produce wood
preservatives, in metal finishing, and other
applications.
Closer inspection of the chemical-use trees
reveals that many of the 33/50 metals are used
to provide similar functions, i.e., use clusters.
For example, pigments/oxides are a final
product of the metals chromium, cadmium, and
lead, while metal finishing (and electroplating)
utilizes the metals chromium, cadmium, and
nickel as products or process materials.
Further evaluation of these product
relationships between the 33/50 metals were
used to identify use clusters that utilize the
greatest fraction and/or greatest number of
metals in the broadest applications. Three
broad application use clusters were identified:
batteries, electroplating (metal finishing), and
pigments. Batteries and electroplating, as the
two largest overall end-uses of the 33/50
metals, were selected for substitutes
assessment.
Battery Manufacture
Cadmium, lead, mercury, and nickel are all
used to manufacture batteries. The metal or
metal compound typically serves as the cathode
or anode material, although mercury is also
used to improve the efficacy of some batteries
by coating the metal electrode to limit the
potential for hydrogen gas evolution.
Batteries have been identified as one of the
largest sources of concentrated metals in the
environment, since they are frequently
discarded by the consumer when they are
depleted.56 A recent study of municipal solid
waste in Vancouver, Canada, however, did not
identify lead-acid batteries as one of the largest
sources of lead in the waste samples analyzed.57
Recent efforts to recycle batteries and produce
rechargeable batteries show promise as a means
of reducing the potential environmental impact
of batteries, but do not provide a complete
solution. While it is recognized that batteries
are an integral part of many technologies and
products, efforts are underway to develop
batteries made from less toxic materials. The
evaluation of safe substitutes in Chapter 5
focuses on battery substitutes of this type.
Evolution of the chemical-use tree diagrams
reveals many products and processes that use
more than one 33/50 metal or metal compound.
Two use clusters, batteries and electroplating,
were selected for substitutes analysis.
Metal Finishing
Metal finishing includes electroplating and
other processes to increase the corrosion
resistance, hardness, aesthetic value, or other
properties of a product. Cadmium, chromium,
and nickel are all widely used to electroplate
metal substrates. Electroplating was selected
for substitute evaluation because of its broad-
range use, because substantial releases to the
environment occur from electroplating (from
both the manufacturing and the disposal of
products), and because a substantial reduction of
14
-------
CHAPTER 1: METALS AND METAL COMPOUNDS
electroplating with the 33/50 metals could
significantly lower the total environmental
releases and hazardous waste disposal of these
metals. Cyanides, another class of 33/50
chemicals (discussed in Chapter 4), are also
used in electroplating.
Frequently, electroplating is only performed
for decorative purposes, although it is more
commonly used to improve the corrosion-
resistance and increase the hardness of the
substrate. Metal finishing technologies are
available that use less toxic chemicals and, in
some cases, less toxic and more environmentally
benign coating technologies may be substituted
for electroplating. Safe-substitutes for 33/50
metals and cyanides in electroplating applications
are discussed in Chapter 6.
Pigments
Inorganic pigments provide color, opacity,
hiding power, and other properties to paints and
coatings, plastics, and inks! Many of these
products are ultimately released to the
environment through paint stripping or disposal
of household products such as plastic containers.
In addition, exposure to inorganic pigments in
household paints is not uncommon, as evidenced
by numerous studies of lead poisoning in
children.
Lead pigments are still used in some
applications, although their use was dramatically
curtailed when the effects of lead exposure from
paints were well documented. Cadmium and
chromium pigments still see wide-spread use.
15
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PARTI; PRIORITY CHEMICALS
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CHAPTER 1: METALS AND METAL COMPOUNDS
ENDNOTES
1 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1992),
Vol. 4.
2 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
Vol. 6.
3 Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1981),
Vol. 14.
4 Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1981),
Vol. 15.
5 Ibid.
6 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A4.
7 "Cadmium," Integrated Risk Information System, April 1994.
8 "Cadmium," Hazardous Substances Data Bank, August 23, 1990.
9 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A4.
10 "Cadmium," Hazardous Substances Data Bank, August 23, 1990.
11 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1986),
Vol. A7.
12 Ibid.
13 "Chromium," Hazardous Substances Data Bank, August 23, 1990.
14 Ibid.
15 Ibid.
16 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1986),
Vol. A15.
17 "Lead," Hazardous Substances Data Bank, January 7, 1991.
18 "Lead," Integrated Risk Information System, April 1994.
19 "Lead," Hazardous Substances Data Bank, January 7, 1991.
20 Ibid.
21
-------
PARTI; PRIORITY CHEMICALS
21 Ullmann's Encyclopedia of Industrial Chemistry, (Weinham: VCH Verlag., 1990), Vol. A16.
22 Ibid.
23 «
"Mercury," Hazardous Substances Data Bank, January 7, 1991.
24 Ibid.
25 "Nickel," Integrated Risk Information System, April 1994.
26 "Nickel," Hazardous Substances Data Bank, October 23, 1990.
27 Ibid.
28 Ibid.
29 Non-Ferrous Metal Data, 1990, American Bureau of Metal Statistics, (Secaucus New Jersey-
Port City Press, Inc., 1991).
30 Mineral Yearbook, 1989, US Dept. of Interior, Bureau of Mines, (Washington: GPO, 1990),
p. 210.
31 Chromium Annual Report: 1990, US Dept. of Interior, Bureau of Mines, (Washington: GPO,
1991).
32 Non-Ferrous Metal Data: 1992, American Bureau of Metal Statistics, Inc., (Secaucus NJ- Port
City Press, Inc., 1993).
33 Lead Annual Report: 1993, US Dept. of Interior, Bureau of Mines, (Washington: GPO, 1994).
34 "Mercury," Mineral Yearbook: 1988-1989, US Dept. of Interior, Bureau of Mines
(Washington: GPO, 1991).
35 Nickel Annual Report: 1992, US Dept. of Interior, Bureau of Mines, (Washington: GPO, 1993).
36 "Cadmium," Mineral Yearbook: 1987, US Dept. of Interior, Bureau of Mines, (Washington:
GPO, 1990).
37 Nickel Annual Report: 1990, US Dept. of Interior, Bureau of Mines, (Washington: GPO, 1991).
38 Ullmann's Encyclopedia of Industrial Chemistry, (Weinham: VCH, Verlag., 1985), Vol. A4.
39 Chemical Technology: An Encyclopedic Treatment, Vol. Ill, 1972, (New York- Earner and
Nobel Books).
40 "Cadmium," Mineral Facts and Problems, US Dept. of Interior, Bureau of Mines
(Washington: GPO, 1985).
Vol. 4.
Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1992),
22
-------
CHAFTER 1: METALS AND METAL COMPOUNDS
41 "Cadmium," Mineral Facts and Problems, US Dept. of Interior, Bureau of Mines,
(Washington: GPO, 1985).
42 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A4.
43 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A4.
Chemical Technology: An Encyclopedic Treatment, Vol. Ill, 1972, (New York: Earner and Nobel
Books).
44 Chromium Annual Report: 1990, US Dept. of Interior, Bureau of Mines, (Washington, GPO,
1991).
45 Ibid.
46 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A3.
Ullmann's Encyclopedia of Industrial Chemistry, (Weinham: VCH Verlag., 1990), Vol. A16.
47 "Lead," Mineral Facts and Problems, US Dept. of Interior, Bureau of Mines, (Washington:
GPO, 1987).
48 "Nickel," Mineral Facts and Problems, US Dept. of Interior, Bureau of Mines, (Washington:
GPO, 1985).
Ullmann's Encyclopedia of Industrial Chemistry, (Weinham: VCH Verlag., 1990), Vol. A17.
Chemical Technology: An Encyclopedic Treatment, Vol. Ill, 1972, (New York: Earner and Nobel
Books).
49 Non-Ferrous Metal Data: 1988, American Bureau of Metal Statistics, (Secaucus, NJ: Port City
Press, Inc., 1989).
"TRI, 1991.
Correspondence from Hampshire Research Assoc., Inc., 1994.
51 Source for Figure 1.1:
Cadmium Annual Report: 1992, US Dept. of Interior, Bureau of Mines, (Washington, GPO:
1993).
52 Sources for Figure 1.2:
Chromium Annual Report: 1992, US Dept. of Interior, Bureau of Mines, (Washington: GPO,
1993).
"Chemical Profile: Sodium Bichromate," Chemical Marketing Reporter, October 14, 1991.
"Chemical Profile: Chromic Acid," Chemical Marketing Reporter, October 21, 1991.
53 Sources for Figure 1.3:
Lead Annual Report: 1992, US Dept. of Interior, Bureau of Mines, (Washington: GPO, 1993).
Correspondence from Halox Pigment Company, September 1993.
23
-------
PARTI; PRIORITY CHEMICALS
1993.
54 Source for Figure 1.4:
"Mercury in 1992," Mineral Industry Surveys, US Dept. of Interior, Bureau of Mines, July 22,
55 Sources for Figure 1.5:
Nickel Annual Report: 1992, US Dept. of Interior, Bureau of Mines. (Washington- GPO 1993)
Correspondence from Nickel Development Institute, 1994.
Tr • s* Characterization of Products Containing Lead and Cadmium in Municipal Solid Waste in the
United States 1970 to 2000, US EPA, Pub. No. 530-SW-89-015C, (Prairie Village, KS, JanuaV?989).
57 A. J. Chandler and Associates, Ltd., Waste Analysis, Sampling, Testing and Evaluation (WASTE)
Program: Effect of Waste Stream Characteristics on MSW Incineration: The Fate and Behavior of Metals
Final Report of the Mass Burn Incineration Study, (Burnaby, B.C., April 1993)
24
-------
CHAPTER 2
ORGANIC CHEMICALS
The 33/50 class of organic chemicals includes
benzene, toluene, mixed or unmixed isomers of
xylenes, methyl ethyl ketone (MEK), and methyl
isobutyl ketone (MIBK). Benzene, toluene, and
xylene (BTX) are members of the chemical
group known as aromatics. MEK and MIBK are
ketones. The 33/50 aromatic compounds are
naturally occurring components of crude oil and
coal tar. MIBK occurs naturally in some foods;
MEK is a synthetic compound not found in
nature.
PHYSICAL PROPERTIES
Selected physical properties and the chemical
formulae of BTX and the 33/50 ketones are
shown in Tables 2.1 and 2.2. respectively. The
physical characteristics of these chemicals are
discussed briefly below.
Aromatic Compounds
Benzene is the basic unit of the aromatic class
of compounds and the source of a wide variety of
synthetic organic chemicals. It is a clear,
colorless, volatile, and flammable liquid that has
a high-octane rating and is thus an important
component of gasolines. Benzene is an excellent
solvent, but its use as a solvent has been almost
eliminated because of its high toxicity.1 Benzene
is thermally stable to oxidation, but may be
oxidized to water and carbon dioxide under
severe conditions.2 Benzene primarily reacts
with other compounds by substitution and
addition.
Toluene is a clear, sweet-smelling, colorless,
and noncorrosive liquid. It is a flammable and
combustible material that may be ignited by heat,
sparks, or flames. After World War II,
petroleum displaced coal tar as the main source
of toluene. Like benzene, toluene has a high
octane rating and therefore is an important
compound of gasoline.3
The xylene isomers are clear, colorless,
volatile, and flammable liquids that have a
characteristic sweet odor and a high octane
rating.4 The technical grade of xylene is a
mixture of ethylbenzene and the three xylene
isomers: o-xylene, m-xylene, and p-xylene.
Because of their similar structures, these three
isomers and ethylbenzene exhibit similar
properties, but their different boiling and
freezing points allow them to be separated. A
typical mixed xylene contains 20 percent o-
xylene. 45 percent m-xylene, 20 percent p-
xylene, and 15 percent impurities.5 The
chemical reactions of xylenes include
isomerization, disproportionate, and
dealkvlation.6
25
-------
PARTI: PRIORITY CHEMICALS
TABLE 2.1 SELECTED PHYSICAL PROPERTIES OF BENZENE, TOLUENE AND
XYLENE ISOMERS
Property
Chemical Formula
CAS No.
Molecular Weight
Boiling Point, at 101.3 kPa, °C
Freezing Point, °C
Specific Gravity, at 20°C
Viscosity, at 20°C, cP
Heat of Vaporization, U/Kg
Heat of Capacity, at 25°C,
kJ/kgK
Heat of Combustion, MJ/kg
Vapor Pressure, kPa
at 0°C
at 20°C
at 30°C
at 40°C
Solubility in Water, at 20°C,
g/kg
Flash Point, °C
Critical Temperature, °C
Critical Pressure, MPa
Critical Density, kg/m3
Benzene
C6H6
71-43-2
78.110
80.1
+5.533
0.8700
0.6468
433.6b
1.708
41.84
3.4660
9.970
24.190
1.13
-11.100
289.40
4.924
300.0
Toluene
C7H8
108-88-3
92.140
110.6
-94.960
0.8667
0.5700
412.3C
1.970
42.44
0.9100
2.9200
7.9100
0.50d
+4.444
318.60
4.109
291.6
o-Xylene
C8H10
95-47-6
106.167
144.4
-25.180
0.8802
0.7500
408.9°
1.771
43.05
0.1670
0.6507
1.181
2.046
Insoluble
+32.220
357.15
3.730
287.7
p-Xylene
C8H10
106-42-3
106.167
138.4
+ 13.260
0.8610
0.6000
395.9°
1.711
42.95
0.2317
0.8685
1.551
2.646
Insoluble
+27.220
343.05
3.511
280.3
Mixed-
Xylenea
C8H10
1330-20-7
106.167
138.4
+ 13.260
0.8610
0.6000
395.9
1.711
42.95
0.2317
0.8685
1.551
2.646
Insoluble
+27.220
343.05
3.511
280.3
Sources:
Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed.,
Solvent Databank (Publication), Texaco Chemical Company'
Peny's Chemical Engineers Handbook
Ullrnann 's Encyclopedia of Industrial Chemistry, 5th ed.
a 50 to 60 percent p-Xylene
bAt80.10°C
c At 25°C
d At 16°C
1978
26
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CHAPTER!: ORGANIC CHEMICALS
TABLE 2.2 SELECTED PHYSICAL PROPERTIES OF 33/50 KETONES
Property
Chemical Formula
CAS No.
Molecular Weight
Boiling Point, at 101.3 kPa, °C
Freezing Point, °C
Specific Gravity, at 20°C
Viscosity, at20°C, cP
Heat of Vaporization, at 101.3 kPa, kJ/mol
Heat of Capacity, at 25°C, kJ/kgK
Heat of Combustion, MJ/kg
Vapor Pressure, at 20°C, kPa
Solubility in Water, at 20°C, g/kg
Flash Point, °C
Critical Temperature, °C
Critical Pressure, MPa
MEK
C4H80
78-93-3
72.10
79.6
-86.4
0.806
0.41
32.8
2.048
0.0338
N/A
26.8
-3.9
260
4.4
MIBK
CoH120
108-10-1
100.16
114.0
-84
0.802
0.61
35.6
1.920
0.0307
2.0
1.9
20
298
3.3
Source:
Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 13, 1978
N/A: Not Available
Ketones
MEK, also known as 2-butanone, is a stable,
colorless, and flammable liquid with an acetone-
like odor.7 It is relatively soluble in water and
miscible with most organic solvents. MEK has
excellent solvency for many natural or synthetic
resins and gums. MEK is generally considered
equivalent to acetone in solvency, but has the
advantages of being less soluble in water and
having a higher boiling point and lower vapor
pressure than acetone.
MIBK, also known as 4-methyl-2-pentanone,
is a widely-used aliphatic ketone solvent. It is
a colorless, stable liquid classified as a
medium boiler. MIBK is miscible with most
organic solvents and with mineral and vegetable
oils.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
The 33/50 organic chemicals each have
health, safety, and environmental issues
associated with their production, use, and
disposal. The following sections summarize
these issues for the aromatic compounds and
the ketones, respectively.
27
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PARTI; PRIORITY CHEMICALS
Aromatic Compounds
Benzene. Benzene is a toxic compound with
both acute and chronic effects. Benzene may
enter the body through inhalation or ingestion, or
by rapid absorption through the skin. The
symptoms for short-term exposure to benzene
include headaches, nausea, euphoria, confusion,
loss of muscular control, and irritation of the
respiratory and gastrointestinal tract. At greater
concentrations, benzene exposure may cause
unconsciousness and even death. Long-term
benzene exposure can cause injury to the nervous
system and bone marrow. The major effect of
chronic toxicity is aplastic anemia. Brain
damage has been found in postmortem studies of
victims of acute and fatal benzene poisoning.
Epidemiologic evidence indicates that benzene
causes leukemia.8 The EPA has classified
benzene as a human carcinogen (weight-of-
evidence Class A).9
The 33/50 organic chemicals each have
health, safety, and environmental issues
associated with their production, use, and
disposal. Benzene, considered the most toxic of
the 33/50 organic chemicals, is a human
carcinogen.
The legal airborne permissible exposure limit
(PEL,) for benzene, as established by
Occupational Safety and Health Administration
(OSHA), is 1 ppm averaged over an eight-hour
workshift. Benzene is also highly toxic to
animiils and plants, especially aquatic life.
Benzene, however, does not persist in the
environment except in groundwater. Benzene
is highly mobile in soil and migrates rapidly to
groundwater when released to soil.
Sources of benzene in the environment
include chemical plants, petroleum refineries,
and combustion of fossil fuels. Human
exposure to benzene occurs in ambient air,
particularly in areas of heavy traffic, near'
production plants, and around gasoline
stations.10
Toluene. The toxic effects of toluene
primarily affects the CNS. Human exposure to
toluene can occur through inhalation and
ingestion. Toluene vapors irritate eyes and
respiratory tract and may cause dizziness,
anesthesia, and confusion. High levels of
exposure cause incoordination, ataxia,
unconsciousness, respiratory arrest, and death.
If ingested, toluene causes vomiting, diarrhea,
depressed respiration, and possibly liver and
kidney damage. Effects on liver, renal, and
nervous systems may be reversible.11 Toluene is
not classifiable as to human carcinogenicity.
There are no human data and inadequate animal
data for classification (weight-of-evidence Class
D).12 Inhalation of glues, paints, or solvents
containing toluene may result in bronchial and
laryngeal irritation and respiratory failure.
Muscular weakness syndromes and other CNS
system damage are also common in toluene
sniffers.
Toluene enters the environment from
evaporating petroleum fuel, toluene-based
solvents and thinners; spills and leaks during
transportation, storage, and disposal of fuels and
oils; releases from petroleum during its
production and as a by-product from styrene
production. Automobile emissions are also a
large source of toluene releases to the
atmosphere. When released on land, toluene is
lost by evaporation and microbial degradation.
Toluene decomposes quickly in soil and readily
evaporates from water. However, since toluene
is relatively mobile in soil, it leaches into the
groundwater where biodegradation will not
occur. When released into surface water,
toluene volatilizes to the atmosphere or
biodegrades. In the atmosphere, toluene
degrades moderately rapidly by its reaction with
photochemically-produced hydroxyl radicals.
Toluene's half-life in the atmosphere ranges
from three hours to one day.13
Xylenes. Acute human exposure to xylenes
may cause irritation of the skin, nose, and throat,
as well as headache, nausea, fatigue, irritability,'
loss of appetite, reduced coordination, and
unconsciousness.14 Respiratory failure may
28
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CHAPTER 2: ORGANIC CHEMICALS
also occur.15 Reported long-term health effects
of xylene exposure include infertility of female
workers, disorders during pregnancy, and signs
and symptoms of neurological changes. Xylene
was not shown to be mutagenic in short-term
tests.16 Xylenes are also EPA Class D, not
classifiable as to human carcinogenicity.17
Xylenes in liquid form are highly toxic to aquatic
life.
Xylene isomers are released into the
environment from fugitive emissions and
automobile exhaust. Industrial sources include
emissions from petroleum refining, coal tar and
coal gas distillation, and from their uses as
solvents for paints and coatings. In addition,
evaporative losses during transport and storage
of gasoline and emissions from production of
other chemicals (e.g., p-xylene for dimethyl
terephthalate and terephthalic acid production)
also contribute to environmental pollution.
When spilled on land, the xylene isomers will
volatilize or be absorbed into the ground. They
may degrade during their passage through the
soil, depending on their concentration, residence
time in the soil, nature of the soil, and the
acclimation of the microbial populations.
However, once xylene reaches the groundwater,
it does not degrade; therefore, xylene is a
common groundwater contaminant. Xylene in
surface waters is lost to the atmosphere by
evaporation. Xylene is not expected to
bioconcentrate.18 In the atmosphere, xylene
reacts with hydroxyl radicals and
photochemically degrades. The half-life for o-
xylene ranges from 1.5 hours in summer to 15
hours in winter, whereas the atmospheric half-
life of p-xylene is 1.7 hours in summer and 18
hours in winter. Despite their rapid degradation,
xylenes are still commonly detected in ambient
air due to the large quantity of xylene
emissions.19
Ketones
Exposure to the 33/50 ketones may occur
through ingestion, inhalation, and skin
absorption. Short-term exposure to MEK or
MIBK can cause nose and throat irritation,
nausea, vomiting, headaches, dizziness, and loss
of coordination or balance. Exposure to MEK
may also cause numbness in the fingers and
arms, numbness and weakness in the legs, and
unconsciousness. MIBK also causes loss of
appetite, diarrhea, and drowsiness. Repeated or
long-term exposure to MIBK can also cause
weakness, eye irritation, stomach pain, sore
throat, fatigue, insomnia, intestinal pain,
enlarged liver, and colitis.20 EPA has assigned
MEK to weight-of-evidence carcinogenicity
Class D, not classifiable as to human
carcinogenicity; MIBK has not been assigned a
weight-of-evidence carcinogenicity classification
by EPA.21
The relatively high solubility of MEK in
water causes it to volatilize slowly. MEK is
mobile in soil. It is moderately toxic to aquatic
life and contributes to smog formation. MEK
does not cause any cumulative toxic effects to
animal life. MIBK is slightly toxic to aquatic life
and is thought to contribute to smog formation.22
MIBK has not been proven to cause any
cumulative toxic effects.
INDUSTRY PROFILE
One or more of the BTX compounds are
produced by at least 26 companies at 43 locations
in the U.S. and its territories. Table 2.3
identifies producers of BTX, their production
capacities, the raw materials they employ hi the
manufacturing process, and the projected
demand for these compounds.
MEK is produced for sale and distribution by
three companies at three locations; MIBK is also
produced for sale and distribution by three
companies at three locations. None of the major
suppliers of MEK and MIBK produce both
compounds. Table 2.4 identifies the producers
of MEK and MIBK, the production processes
they use, their capacities, and the projected
demand for these chemicals.
BTX Market Trends
The total production capacity of benzene in
1990 was 17.3 billion pounds; the 1990
consumption or demand for benzene was 13.5
29
-------
PARTI; PRIORITY CHEMICALS
TABLE 2.3 SUPPLY AND DEMAND OF BTX COMPOUNDS
Producer
Amerada Hess Corp.
St. Croix, Virgin Islands
Amoco Corp.
Texas City, TX
Decatur, AL
Whining, IN
AroChem International.Inc.
Penuelas, Puerto Rico
Ashland Oil, Inc.
Cattlesburg, KY
BP America, Inc.
Alliance, LA
Lima, OH
Chevron Corp.
Philadelphia, PA
Port Arthur, TX
1 Pascagoula, MS
CITGOCorp.
1-ake Charles, LA
Corpus Christi, TX
The Coastal Corp.
Westville, NJ
Corpus Christi, TX
Dow Chemical U.S.A.
Freeport, TX
Plaquemime, LA
Exxon Corp.
Baton Rouge, LA
Baytown. TX
FINA
Port Arthur, TX
Huntsman Chemical Corp.,
Bayport, TX |
— f
Kerr-McGee Corp.
Corpus Christi, TX
Koch Industries, Inc.
Corpus Christi, TX
Lyondell Co.
Channelview, TX
Houston. TX
Benzene
559
798
580
544
472
834
276
943
421
566
109
595
—•••—— •••••••
363
1451
834
1067
•"•"•••••••••••••••••••I
464
109
^_L
123
617
—•— •—•— -^— , .
871
435
•••••••••••••••••••••••••I
Toluene
672
1771
398
•••••••••••••••••••••
260
470
723
•••••••••••••••••••••••I
181
311
159
398
j
159
1330
•••••••••••••••••••••I
1055
296
730
333
217
— — •— . _•_
1992 Capacity (million Ibs/yr)
o-Xylene
198
^•••^•N^MMMMMi
—
286
.,
176
242 1
p-Xylene
1479
1084
"•••••••••••••••••••••I
•••— •-^—•••«.
510
>^M^^M«HM^BM
977
•••"••••"••••••••••••••I
855
424
Mixed
Xylenes
1070
1429
1400
941
180
••»••«•••••••••••••••••
431
553
237
503
1723
682
215
1249
747
••••MBINBMHBBBHHB^B
Raw Material and Remarks*
CR and T:NC
CR:PC and PYG:PC
CRandT
1 COLO:FC and CR and T:FC
CR:NC and T
1 CR:NC and T
CR:FC and T:FC
CR:PC and PYG:PG and T'PC
CR
CR and T'FC
CR
T:FC and CR
PYG:FC and T:FC
PYGrFC and T:FC
CR and PYG:NC
CR:NC and PYG and XIS
CR:PC and T:PC and T:FC
T:FC
CR:NC
CR:FC and T:FC and XIS
PYG:FC and CR:NC
T:NC
-
30
-------
CHAPTER!: ORGANIC CHEMICALS
Producer
Mobil Corp.
Beaumont, TX
Chalmette, LA
Occidental Corp.
Chocolate Bayou, TX
Corpus Christi, TX
Phillips Co.
Sweeney, TX
Guayama, Puerto Rico
Salomon, Inc.
Houston, TX
Shell Oil Co.
Deer Park, TX
Wood River, IL
Sun Co., Inc.
Marcus Hook, PA
Toledo, OH
Tulsa, OK
Texaco, Inc.
Delaware City, DE
El Dorado, KS
Port Arthur, TX
The UNO-YEN Co.
Lemont, IL
USX Corp.
Texas City, TX
TOTAL CAPACITY
1992 Capacity (million Ibs/yr)
Benzene
726
145
726
580
80
600
36
1125
363
276
145
210
109
109
479
138
51
18,930
Toluene
361
275
181
145
210
535
101
217
347
463
152
296
80
448
137
145
13,650
1990 Demand
1991 Demand
1992 Demand
1993 Demand
1996 Demand
13,500
N/A
13,790
14,150
N/A
N/A
N/A
N/A
N/A
N/A
o-Xytene
161
132
1,195
N/A
950
980
N/A
1050
p-Xylene
165
560
6,050
Mixed
Xylenes
359
144
266
725
79
395
187
373
72
79
14,040
N/A
5310
5440
N/A
6010
N/A
N/A
N/A
N/A
N/A
Raw Material and Remarks*
CR.NC and PYG
CR:NC
PYG and T
PYG and T
CR and FC
CR:PC and T:FC
CR:NC
CR:PC and PYG:PC
CR:NC
CR:NC and T:NC
CR:FC
CR and COLO: NC
Sources:
Capacity data: 7992 Directory of Chemical Producers: United States of America, SRI International
Demand Estimates: Chemical Marketing Reporter
N/A: Not Available
Abbreviations (apply to Benzene only):
CR: Catalytic Reformate T: Toluene
XIS: Xylene Isomerization COLO: Coke-Oven Light Oil
Arco Chemical went bankrupt in 1993
Additional companies which began producing benzene in 1993 are: Marathon (51 million Ib/yr) and Phibro (36 million
Ib/yr)
PYG: Pyrolysis Gasoline PC: Partly Captive Use
NC: No Captive Use FC: Fully Captive Use
31
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PARTI; PRIORITY CHEMICALS
TABLE 2.4 SUPPLY AND DEMAND OF 33/50 KETONES
Producer
Union Carbide
Institute, WV
Captive acetone; co-products are MIBK and
Capacity3-6 (million Ibs/yr)
Exxon Chemical Co.
Baton Rouge, LA
Dehydrogenation of sec-butyl alcohol
Hoechst Celanese Co.
Butane oxidation
Shell Chemical Co.
Dehydrogenation of sec-butyl alcohol
Shell Chemical Co.
Deer Park, TX
Captive acetone; co-product is MIBK
Tennessee Eastman Co.
Kingsport, TN
Purchased acetone; co-product is DIBK
Capacity and demand information from Chemical Marketing Reporter
Process info: 7992 Directory of Chemical Producers: United States of America, SRI International
"Capacities may vary depending on product mix
billion pounds.23 In 1992 capacity and
consumption were 18.9 billion and 13.8 billion
pounds, respectively. The demand for benzene
is projected to grow 2.5 to 3.5 percent per year
through 1997.24 The supply and demand are
expected to remain in balance provided that the
demand for styrene and cyclohexane, two
products manufactured from benzene, remains
stable.25
The U.S. had the capacity to produce
approximately 13.7 billion pounds of toluene in
1992.26 Future fuel regulations and standards
could influence the demand for toluene, one of
the high octane components of gasoline.
Although the octane requirements for gasoline
are expected to increase, stricter controls on
volatile organic compounds (VOCs) could
eventually cause decreased demand for toluene in
32
-------
CHAPTER!: ORGANIC CHEMICALS
fuel.27 Since almost half of the toluene produced
is used to manufacture benzene, the demand for
benzene as a chemical raw material could also
influence the market for toluene.
The future market for the 33/50 aromatics is
linked to their use as chemical intermediates in
the production of plastics and resins:
• benzene is used to produce styrene and
cyclohexane (used to produce nylon);
• toluene is used to produce benzene;
• o-xylene is used to produce phthalic
anhydride (used to produce PET and alkyd
resin); and
• xylene is used to produce PET fibers and
resins.
The annual capacity of mixed xylenes
producers in 1992 was 14 billion pounds.28 The
projected growth rate of p-xylenes is 4.5 percent
per year through 1993, based on the strength of
the dimethyl terephthalate and terephthalatic acid
(DMT-PTA) market.29 P-xylene is a chemical
intermediate in the manufacture of DMT-PTA,
which are used to produce polyethylene
terephthalate (PET) fibers and resins. The
estimated growth rate of o-xylene is 2.5 percent
per year through 1993. The future for o-xylene
is strongly tied to the production of phthalic
anhydride because its production consumes about
90 percent of the o-xylene produced.30
Reformulated Gasoline. In April of 1992,
EPA published a supplemental notice of proposed
rulemaking on the standards and enforcement
scheme for reformulated, conventional gasoline
under the Clean Air Act (CAA). The notice
supplemented the proposal for the reformulated
gasoline program that was originally published in
July of 1991. The proposed rulemaking is
intended to meet the CAA requirements that: 1)
gasoline sold in the nine worst ozone
nonattainment areas be reformulated to reduce
toxic and ozone-forming VOC emissions; and 2)
gasoline sold in the rest of the U.S. be prohibited
from becoming more polluting than gasoline sold
in 1990.
Among other things, the CAA requires that
reformulated gasoline shall comply with the
more stringent of a gasoline formula provided in
the Act or performance standards. The
reformulated gasoline formula limits benzene
content to not more than one percent by volume,
and total aromatic hydrocarbon content to not
more than 25 percent by volume. The Act
allows the EPA administrator to determine the
composition of gasoline sold or introduced into
commerce in 1990, but provides baseline
gasoline fuel properties if no adequate or reliable
data exist regarding the composition of gasoline
in 1990. Among other components, the baseline
gasoline defined in the Act contains 1.53 percent
benzene and 32 percent aromatics. Clearly,
implementation of the standards for reformulated
gasoline will affect the chemical market for BTX
compounds. A reduction in the concentration of
BTX in gasoline may cause producers to place
new emphasis on the use of these chemicals as
chemical intermediates.
Ketones Market Trends
The U.S. produced 482 million pounds of
MEK in 1988, with 424 million pounds being
sold that same year (selling for a total value of
$ 166 million).31 Production capabilities and
demand increased to 540 and 490 million
pounds, respectively, in 1992.32 The long term
outlook for MEK is that its usage will decline by
two percent per year as stricter VOC restrictions
are introduced.33
Approximately 205 million pounds of MIBK
were manufactured and 159 million pounds were
sold in 1988 (selling for a total value of nearly
$60 million).34 For 1992 these figures increased
to 225 and 175 million pounds, capacity and
demand respectively.35 Small amounts of this
ketone can be formed as by-products of other
processes, which can then be used on the plant
site or sold for a modest profit. The long-term
outlook is that usage of MIBK will decline
slightly as stricter VOC legislation is passed.36
33
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PARTI; PRIORITY CHEMICALS
Price of the 33/50 Organic Compounds
The prices of the 33/50 organic compounds
have fluctuated over the years. The price of
the 33/50 aromatics are directly linked to the
price of crude oil. Table 2.5 presents the
historical price range and current prices. The
current prices for each of the compounds are in
the rnid-to-upper historical price range. The
price of MIBK is at its historical high.
PRODUCTION PROCESSES
BTX compounds are produced from
petroleum and, less commonly, as a byproduct of
the carbonization of coal to produce coke for the
steel industry. MEK and MIBK are produced
from sec-butyl alcohol and acetone, respectively.
The following sections discuss processes for
producing BTX from crude oil and
manufacturing MEK and MIBK.
BTX Production Processes
Crude oil is composed primarily of paraffins,
naphthenes, and aromatic compounds in varying
proportions. Crude oil processing involves
primary distillation followed by one or more of
several conversion and/or upgrading processes to
yield the desired final products. Figure 2.1
illustrates the products manufactured from crude
oil and the estimated volume fraction of crude
oil that is used to produce each product.37
Finished gasoline, fuel oil, and jet fuel are by
far the most dominant products of crude oil.
Petrochemical feedstock, which is used to
produce BTX and other chemicals, comprises
approximately three percent by volume of the
products of crude oil.
The two most common sources of BTX from
petroleum are the catalytic reforming process
and pyrolysis gasoline. Portions of the toluene
and xylene from these sources are also used as
feed streams to additional processes to produce
benzene. Figure 2.2 depicts the sources of BTX
derived from crude oil.38 Table 2.6 lists the
production capacity for BTX compounds by the
most commonly employed processes.
Catalytic Reforming. Catalytic reforming is
a platinum-catalyzed, high temperature (470 to
530°C) process in which nonaromatic
hydrocarbons are converted to an aromatic
product called reformate. The feed stream to the
reforming process, petroleum feedstock of
Figure 2.1, consists of C6 to C12 hydrocarbons in
the 70 to 190°C boiling range (e.g., light
petroleum distillate or straight run naphtha).
TABLE 2.5 PRICES OF 33/50 ORGANIC COMPOUNDS
Chemical
Benzene
Toluene
o-Xylene
p-Xylene
MEK
MIBK
— • _
Historical ($/lb)a
High
2.25
N/A
0.26
0.33
0.50
0.51
—— — — — — — — — — — — _ i
Low
i —
0.21
N/A
0.03
0.0625
0.0925
0.12
'"
Current ($/lb)b
c^
.OJ
0.67
0.155
0.23
0.40
0.51 to 0.53
Source:
Chemical Marketing Reporter
' MEK' «*
1964-1989 for o-Xylene; and from
b Current price for industrial grade, bulk quantity, as of week ending February 4 1994
N/A: Not Available '
34
-------
CHAPTER 2: ORGANIC CHEMICALS
AUTOMOTIVE
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PARTI; PRIORITY CHEMICALS
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36
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CHAPTER!: ORGANIC CHEMICALS
TABLE 2.6 PRODUCTION CAPACITY OF BTX COMPOUNDS BY PROCESS CAPACITY
Chemical
Benzene
Toluene
Mixed
Xylenes
TOTAL
BTX
Production Capacity (million Ib)
Catalytic
Reformate
8,576
12,657
12,882
34,120
Pyrolysis
Gasoline
4,346
904
187
5,437
Toluene
Feed
5,398
—
948
6,346
Coke Oven
Light Oil
450
59
22
531
Xylene
Isomerization
160
29
189
Total
18,930
13,650
14,040
46,620
Source:
7992 Directory of Chemical Producers: United States of America, SRI International
The composition of these streams varies with the
source of the crude oil resulting in a variable
reformate composition; more C6 to C8
nonaromatics result in more benzene and
toluene. Pretreatment prior to catalytic
reforming is required to remove impurities of
sulfur, nitrogen, and oxygen. Chemical
reactions involved in catalytic reforming may
include dehydrogenation of naphthenes to
aromatics, dehydrocyclization of paraffins to
aromatics, or isomerization of alkylnaphthenes
followed by dehydrogenation.39
Typical ratios of reformate BTX
concentrations are approximately 1:4:5,
benzene:toluene:xylene, with the fraction of
BTX near 60 percent of reformate. A large
portion of the remaining 40 percent of the
reformation product, between 18 to 35 percent,
contains nonaromatics. These nonaromatics are
removed by an extraction process, which leaves
benzene, toluene, and C8 and C9+ aromatics.
The aromatics are preferentially dissolved and
separated from the nonaromatic compounds, and
recovered by distillation.40
The aromatic content of the reformate is not
only dependant on the composition of the feed,
but also directly related to the severity of
catalytic reforming (e.g., temperature and
process time); increasing the severity increases
the aromatic concentration of the product. An
increase in the concentration of BTX
compounds enhances the octane level of
gasolines, and thus increases the research
octane number (RON). The RON is used to
indicate the relative degree of reforming
severity. In this manner, BTX processing and
the gasoline production industry are closely
linked. The removal of BTX from gasoline
pools for chemical processing can thus
influence the cost and performance of
gasoline.41
Pyrolysis Gasoline. Pyrolysis gasoline, or
dripoline, is another source of BTX. Pyrolysis
gasoline is produced as a by-product from the
high-temperature, short-residence time cracking
of paraffin gases, naphthas, gas oils, or other
hydrocarbons in the production of ethylene.
The quantity of pyrolysis gasoline produced
from the cracking of crude oil fractions is a
function of feedstock and operating conditions,
and is increased when heavier charge stocks are
used.42 A larger yield of toluene and xylene,
relative to benzene, is produced by increasing
the boiling point of the feed.
The BTX content of pyrolysis gasoline is
greater than 60 percent. Pyrolysis gasoline
37
-------
PARTI: PRIORITY CHEMICALS
also contains other unsaturates and diolefins
(> 5 percent) which cause instability in the
BTX product. If used as an aromatic product,
this instability problem is controlled by a two-
stage process; stage one involves the
conversion of diolefins to oletlns by
hydrotreatment, stage two is the saturation
oftheolefins.43
Toluene Feed. The disproportionate
production of toluene over benzene in catalytic
reformation requires additional processing to
create more benzene, the higher valued
product. Two processes are utilized to convert
toluene and other low weight aromatics to
benzene and xylene; disproportionation and
hydrodealkylation. Disproportionation is an
equilibrium reaction where toluene is used to
produce benzene and xylene isomers. In the
disproportionation reaction, a methyl group is
transferred from a molecule of toluene to a
second molecule of toluene to yield one molecule
of benzene and one molecule of xylene.
Operating temperatures range between 350 and
525°C. Hydrodealkylation may be purely
thermal or catalyzed by metals or supported
metal oxides. Typical catalytic reaction
conditions include an operating temperature
between 575 to 650°C, an elevated pressure, and
a chromium-alumina or platinum-alumina
catalyst in the presence of hydrogen. The
thermal process is carried out under higher
temperatures without a catalyst present. Both
processes are used to manufacture benzene of
high purity and xylenes containing less than
one part per billion of saturated
hydrocarbons.44
Separation of Mixed Xylenes. Mixed
xylenes may be separated into the different
xylene isomers by the following processes:
• o-xylene may be separated from m-xylene by
a two stage distillation column, as the boiling
points of these isomers differ by
approximately 5°C;45 or
• p-xylene may be separated from the mixed
isomers by a crystallization or adsorption
process because it has a significantly higher
freezing point than the other isomers.46
Generally, the individual isomers are isolated
from mixed xylenes through further steps
including distillation, fractionation,
crystallization, adsorption, and solvent
extraction.
Ketone Production Processes
The vapor-phase dehydrogenation of sec-
butyl alcohol, used to produce approximately
85 percent of the MEK in the U.S., is similar
to the manufacture of acetone from
isopropanol. The first step in this two-step
process is the hydrogenation of butenes to 2-
butanol by mixing with aqueous sulfuric acid.
Then the 2-butanol is dehydrogenated with a
zinc- or copper-based catalyst at high
temperatures (400 to 500°C) and low pressures
(less than 3.4 atmosphere).47 Another source
for MEK is as a by-product of liquid-phase
oxidation of butane to acetic acid. Hoechst
Celanese in Pampa, Texas reportedly uses this
process to produce MEK.
The most common method for the
production of MIBK is the conversion of
acetone in three steps. The first step consists of
a liquid-phase condensation of acetone in an
alkaline fixed bed reactor. This produces
diacetone alcohol, which is then dehydrated by
an acid-catalyzation procedure at 100°C. The
resulting mesityl oxide is selectively
hydrogenated over a nickel catalyst.48 Other
catalysts that can be used effectively for this
third step are copper, nickel-chromium, and
palladium.
Another commercially feasible method for
the production of MIBK is the Hibernia
Scho'lven process. Dilute sodium hydroxide
and acetone are fed to a reactor which is
allowed to run until the reaction has been
completed. Phosphoric acid is then added to
stabilize the product which is sent to the first
column to remove the remaining acetone.
More phosphoric acid is added to the resulting
diacetone alcohol bottoms mixture and is fed to
38
-------
CHAPTER!: ORGANIC CHEMICALS
the dehydrating column. The head mixture of
this second column is mostly mesityl oxide and is
purified to 98 percent in the third column. The
fourth and last column is where the mesityl oxide
is hydrogenated over a palladium catalyst to form
MIBK.49
ENVIRONMENTAL RELEASES OF THE
33/50 ORGANIC COMPOUNDS
Environmental releases of the 33/50 organic
compounds occur from their production, use,
and disposal. The types of releases and transfers
that occur from production facilities and the
releases and transfers reported by the major
producers of these chemicals in the 1991 TRI are
discussed below. Also presented is the
distribution of environmental releases by industry
group.
Environmental Releases from Production
Facilities
Air emissions of organic compounds from
production processes can originate from the
continuous or intermittent purging of inert gases
from reactor vessels, drying beds, finishing
columns, and other process vessels. Fugitive air
emissions result when process fluid leaks from
plant equipment such as pumps, compressors,
process valves, and other equipment. Air
emissions from storage and handling operations
also occur at production facilities. Other sources
of environmental releases or transfers include the
following:
• wastewater discharges directly from the plant
into rivers, streams, or other bodies of water,
or transfers to a publicly owned treatment
works (POTW);
• on-site release to landfills, surface
impoundments, land treatment, or another
mode of land disposal;
• disposal of wastes by deep-well injection;
and,
• transfers of wastes to off-site facilities for
treatment, storage, or disposal.
Aromatic Compounds. Table 2.7 presents
the releases and transfers of BTX compounds
from petroleum refining (SIC 2911) reported in
the 1991 TRI. These releases and transfers are
an overstatement of the releases and transfers
that would result simply from petrochemical feed
production, but they are an indicator of the large
volume of BTX released and transferred at the
front end of the petroleum products
manufacturing process. Using the principles of
life cycle assessment and assuming that about
three percent of crude oil is used to manufacture
petrochemical feedstock (see Figure 2.1), about
three percent of these releases (740 thousand
pounds of BTX) can be attributed to
petrochemical feed production.
Environmental releases of BTX from
production occur from the initial distillation of
crude oil through the various production
processes outlined above. However, the primary
releases from the conversion of crude oil into
petroleum products are nonaromatic organic
compounds (the light and heavy reformate from
distillation column) and the solvents used in the
extraction vessels. The used solvent is usually
recovered or recycled and the nonaromatic
compounds can be distilled based on their
different boiling points. Thus the light or heavy
reformates can be used or disposed depending on
their characteristics.
Ketones. The environmental releases and
transfers of MEK and MIBK from the major
producers identified in Table 2.3, plus releases
and transfers from producers that were active in
1991 but have since shut down their plants, were
retrieved from the 1991 TRI database. The data
are presented in Table 2.8. Many of the
facilities reported multiple SIC codes on one
form, indicating the data may include releases
from internal use of the chemicals after
production.
39
-------
PARTI: PRIORITY CHEMICALS
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1 TOTAL
40
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CHAPTER!: ORGANIC CHEMICALS
00
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TOTAL
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41
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PARTI: PRIORITY CHEMICALS
Distribution of Environmental Releases by
Industry Group
Each of the 33/50 organic chemicals were
within the top 40 chemicals for TRI total releases
and transfers in 1991. Table 2.9 lists their total
releases and transfers and relative rank. Toluene
contributed the largest percentage of total
emissions for this chemical class, accounting for
42 percent of the total releases and transfers of
the 33/50 organic chemicals.50
Releases and transfers of the 33/50 organic
compounds were fairly widely distributed across
industry groups in 1991. The top seven
industries that emitted the largest quantities of
33/50 organic compounds and their total reported
releases and transfers are listed in Table 2.10.
The chemicals and allied products industry,
which includes plastics and resins manufacturers,
reported the largest total emissions of the 33/50
organic compounds, followed by the
transportation industry and companies that listed
multiple SIC codes. Releases from the
chemicals and allied products industry result
from using the compounds as chemical
intermediates, as solvents, and as chemical
processing aids. Releases from the
transportation industry can probably be largely
attributed to the use of these materials as solvents
in paints and coatings and as cleaning solvents.
Environmental releases and transfers of the
33/50 organic chemicals were widely distributed
across industry groups in 1991. The chemicals
and allied products industry reported the
greatest releases of benzene, toluene, and m-,
o- andp-xylene, probably from their use as
chemical intermediates, solvents, and chemical
processing aids. Rubber and plastic products
manufacturers reported the largest releases of
MEK; manufacturers of transportation
equipment had the greatest releases ofMIBK
and mixed xylenes.
USES OF THE 33/50 ORGANIC
CHEMICALS
The BTX compounds are widely used as
chemical intermediates in the manufacture of
plastics and resins and other chemicals and as
solvents. The primary use of MEK and MIBK is
as a coatings solvent. The uses are illustrated in
chemical-use tree diagrams. Figure 2.3 presents
the uses of benzene to produce major chemical
intermediates.51 Figures 2.3.1 through 2.3.4
present the products manufactured from the
major chemical intermediates.52
TABLE 2.9 TOTAL RELEASES AND TRANSFERS OF 33/50 ORGANIC CHEMICALS
Chemical
Toluene
Mixed Xylenes (all)
MEK
MIBK
Benzene
TOTAL
Releases and Transfers (Ibs/yr)
223,500,172
146,677,780
114,870,964
30,795,824
20,860,044
536.704.784
TRI Rank
5
9
11
30
37
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc., Inc.
U.S., EPA, Office of Pollution Prevention and Toxics, 33/50 Program Office
42
-------
CHAPTER!: ORGANIC CHEMICALS
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TOTAL RELEASES
AND TRANSFERS
00
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43
-------
PARTI: PRIORITY CHEMICALS
Figure 2.4 presents the uses of toluene and its
major chemical intermediate, toluene-
diisocyanate.53 Figure 2.5 is the chemical-use
tree for xylene.54 Figures 2.6 is the chemical-use
tree diagram for MEK and MIBK.55
The 33/50 aromatics are the basic building
blocks of many of the plastics and resins in use
today. Toluene, xylene, MEK, and MIBK are
widely used as solvents in paints and coatings.
These use clusters were selected for substitutes
evaluation.
The numbers along each branch of the
chemical-use tree are weight fractions of the
usage of the chemical or product in the first box
to produce the chemical or product in the second
box. For example, in Figure 2.3, 53 percent of
the benzene produced is used to manufacture
ethylbenzene; 99 percent of the ethylbenzene
produced is used to produce styrene monomer.
Many of the 33/50 organic chemicals are used
to produce variations of a similar product, i.e.,
use clusters. Plastics and resins, and paint and
coating solvents are the two use clusters which
have the broadest applications or uses of these
chemicals. Consequently, these use clusters
were selected for evaluation of substitutes and
are discussed briefly below.
Plastics and Resins
Benzene, toluene, and the xylene isomers
are the basic building blocks of many of the
myriad plastics and resins in widespread use
today. Cyanide compounds and
dichloromethane, two other 33/50 chemicals,
are also used to produce certain plastics and
resins. Further, some of the 33/50 metals are
used as pigments in consumer products made
from plastics and resins. The evaluations in
Chapter 7 focus on safe substitutes for products
made from the styrene monomer that is
manufactured from benzene. A side benefit of
reductions in the use of certain plastics and resins
to reduce BTX releases could be a reduction in
the use of toxic inorganic pigments.
Paints and Coatings
Toluene, xylene, MEK, and MIBK are widely
used as solvents or diluents in paints and
coatings, including industrial or consumer grade
materials. Solvents provide several functions in
paints and coatings, the most important of which
is to decrease the coating's viscosity so that it
may be applied in a thin film to the substrate.
The 33/50 organic chemicals are widely used
because they have good solvency power for a
wide variety of the resins used in paints and
coatings.
In consumer applications all the solvent in a
paint is released to the atmosphere. In industrial
applications control technologies are typically
employed to reduce the release of these toxic
chemicals to the environment, but releases and
transfers still occur in substantial amounts. In
both applications, workers may be exposed to the
chemical by inhalation as it evaporates. With
increased concern about the effects on worker
safety and on the environment, substantial
progress has been made in developing new low-
solvent paint formulations, like water-borne
paints or powder coatings. The substitutes
analysis in Chapter 8 examines and evaluates
these new, safer substitutes.
44
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CHAPTER 2: ORGANIC CHEMICALS
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NOTE: Reliable data were not available to estimate weight fractions along some branches of the chemical-use tree
46
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CHAPTER 2: ORGANIC CHEMICALS
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CHAPTER!: ORGANIC CHEMICALS
ENDNOTES
1 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A3.
2 Ibid.
3 Kirk-Other Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1978),
Vol. 24.
4 Xylene: Chemical Information Sheet, Illinois Environmental Protection Agency, Office of
Chemical Safety, January 1989.
5 Hampshire Research Associates, Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, 1989).
6 Kirk-Other Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1978),
Vol. 24.
7 Kirk-Other Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1978),
Vol. 13.
8 "Benzene," Hazardous Substances Data Bank, November 1993.
9 "Benzene," Integrated Risk Information System, April 1994.
10 Benzene: Chemical Information Sheet, Illinois Environmental Protection Agency, Office of
Chemical Safety, January 1989.
11 "Toluene," Hazardous Substances Data Bank, October 1990.
12 "Toluene," Integrated Risk Information System, April 1994.
13 "Toluene," Hazardous Substances Data Bank, October 1990.
14 Xylene: Chemical Information Sheet, Illinois Environmental Protection Agency, Office of
Chemical Safety, January 1989.
15 ti
o-Xylene," Hazardous Substances Data Bank, October 22, 1990.
16 Xylene: Chemical Information Sheet, Illinois Environmental Protection Agency, Office of
Chemical Safety, January 1989.
17 "Xylene," Integrated Risk Information System, April 1994.
18 "p-Xylene," Hazardous Substances Data Bank, October 1990.
19 "o-Xylene," Hazardous Substances Data Bank, October 1990.
53
-------
PARTI: PRIORITY CHEMICALS
20 Hampshire Research Associates, Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, 1991).
"MEK," Hazardous Substances Data Bank, August 1993.
"MIBK," Hazardous Substances Data Bank, January 1991.
21 "Methyl Ethyl Ketone," Integrated Risk Information System, June 1993.
Methyl Isobutyl Ketone," Integrated Risk Information System, August 1993.
22 Hampshire Research Associates, Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, 1991).
23 "Chemical Profile: Benzene," Chemical Marketing Reporter, April 23, 1990.
24 "Chemical Profile: Benzene," Chemical Marketing Reporter, June 28, 1993.
25 "Chemical Profile: Benzene," Chemical Marketing Reporter; April 23, 1990.
26 7992 Directory of Chemical Producers: United States of America, SRI International.
27Cherry C. Lewis, BTX: More of the Same Rocky Road, (CPI Purchasing, 1989), Vol. 7, 38.
287992 Directory of Chemical Producers: United States of America, SRI International.
29 "Chemical Profile: Para-Xylene," Chemical Marketing Reporter, August 7, 1989.
30 "Chemical Profile: Ortho-Xylene," Chemical Marketing Reporter, July 31, 1989.
31 Synthetic Organic Chemicals: United States Production and Sales 1988, US International Trade
Commission, Pub. No. 2219, (Washington: GPO, 1989), Vol. 5, 15.
32 "Chemical Profile: Methyl Ethyl Ketone," Chemical Marketing Reporter, July 26, 1993.
33 "Chemical Profile: Methyl Ethyl Ketone," Chemical Marketing Reporter, August 27, 1990.
34 Synthetic Organic Chemicals: United States Production and Sales, 1988, US International Trade
Commission, Pub. No. 2219, (Washington: GPO, 1989), Vol. 5, 15.
35 "Chemical Profile: Methyl Isobutyl Ketone," Chemical Marketing Reporter, August 2, 1993.
36 "Chemical Profile: Methyl Isobutyl Ketone," Chemical Marketing Reporter, August 20,
1990.
37 Sources for Figure 2.1:
7992 Directory of Chemical Producers: United States of America, SRI International.
Petroleum Supply Annual: 1990, US Department of Energy, Energy Information Administration.
38 Source for Figure 2.2:
7992 Directory of Chemical Producers: United States of America, SRI International.
54
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CHAPTER 2: ORGANIC CHEMICALS
39 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A3.
40 Ibid.
41 Kirk-Other Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
Vol. 4.
42 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A3.
43 Ibid.
44 Ibid.
45 Kirk-Other Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1978),
Vol. 24.
46
Ibid.
47 Kirk-Other Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1978),
Vol. 13.
48 Ibid.
49 Ibid.
50 Hampshire Research Associates, Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, September 1991).
51 Sources for Figure 2.3:
"Chemical Profile: Benzene," Chemical Marketing Reporter, June 28, 1993.
"Chemical Profile: Ethylbenzene," Chemical Marketing Reporter, July 13, 1992.
"Chemical Profile: Cumene," Chemical Marketing Reporter, September 20, 1993.
"Chemical Profile: Cyclohexane," Chemical Marketing Reporter, October 26, 1992.
"Chemical Profile: Nitrobenzene," Chemical Marketing Reporter, August 30, 1993.
52 Sources for Figures 2.3.1 through 2.3.4:
"Chemical Profile: Styrene," Chemical Marketing Reporter, September 21, 1992.
"Chemical Profile: Polystyrene," Chemical Marketing Reporter, June 24, 1991.
"Chemical Profile: ABS Resins," Chemical Marketing Reporter, April 22, 1991.
"Chemical Profile: SB Rubber," Chemical Marketing Reporter, May 27, 1991.
"Chemical Profile: Phenol," Chemical Marketing Reporter, September 13, 1993.
"Chemical Profile: Acetone," Chemical Marketing Reporter, September 6, 1993.
"Chemical Profile: Bisphenol A," Chemical Marketing Reporter, August 16, 1993.
"Chemical Profile: Caprolactan," Chemical Marketing Reporter, Octobers, 1992.
"Chemical Profile: Polycarbonate," Chemical Marketing Reporter, May 10, 1993.
A. Knopp and L.A. Pilato, Phenolic Resins, (New York: Springer-Verlag, 1985).
Clayton May, ed., Epoxy Resins: Chemistry and Technology, (New York: Marcel Dekker, 1988).
55
-------
PARTI; PRIORITY CHEMICALS
——— in
"Chemical Profile: Adipic Acid," Chemical Marketing Reporter, November 23 1992
"Resins 1994: Plotting a Course for Supply," Modern Plastics, January 1994.
"Chemical Profile: Aniline," Chemical Marketing Reporter, August 23, 1993
"MethyleneDiisocyanate," Chemical Marketing Reporter, October 18/1993.
53 Source for Figure 2.4:
"Chemical Profile: Toluene Diisocyanate," Chemical Marketing Reporter, October 11, 1993.
54 Sources for Figure 2.5:
"Chemical Profile: Paraxylene," Chemical Marketing Reporter, July 20, 1992.
"Chemical Profile: Orthoxylene," Chemical Marketing Reporter, August 3 1992
"Chemical Profile: DMT - PTA," Chemical Marketing Reporter, July 27, 1992
"Chemical Profile: Phthalic Anhydride," Chemical Marketing Reporter, August 10, 1992.
55 Sources for Figure 2.6:
"Chemical Profile: Methyl Ethyl Ketone, Chemical Marketing Reporter July 26 1993
"Chemical Profile: Methyl Isobutyl Ketone," Chemical Marketing Reporter, August 2/1993.
56
-------
CHAPTERS
HALOGENATED ORGANIC
COMPOUNDS
The six halogenated organic compounds on
EPA's 33/50 list are dichloromethane (methylene
chloride or DCM), chloroform (CFM), carbon
tetrachloride (CTC) ,1,1,1 -trichloroethane
(TCA), trichloroethylene (TCE), and
tetrachloroethylene (perchloroethylene or PCE).
Each of these compounds is primarily a synthetic
substance, although DCM and CFM occur
naturally in small amounts.
These 33/50 compounds belong to two distinct
families of chemical compounds. DCM, CFM,
and CTC belong to the family commonly known
as the chloromethanes. TCA, TCE, and PCE
are chlorinated ethanes and ethylenes.
PHYSICAL PROPERTIES
The 33/50 halogenated organic compounds
share several common physical features. They
are volatile, colorless, nonflammable liquids
characterized by a sweet or ether-like odor.
Their high chlorine content gives their liquids
and vapors relatively high density and also
reduces their ability to support combustion.
They are subject to decomposition by hydrolysis
with water and by high temperatures, oxygen,
and sunlight. They are only slightly soluble in
water and are miscible with most organic liquids.
Table 3.1 shows selected physical properties and
the chemical formulae of these compounds.
DCM is only slightly soluble in water, and is
completely miscible with other grades of
chlorinated solvents, diethyl ether, and ethyl
alcohol. It also dissolves in most other common
organic solvents. DCM, in its pure form,
exhibits no flash point, but it will have a flash
point if small amounts of other volatile solvents
are added. DCM is one of the more stable of the
chlorinated hydrocarbons, with its initial thermal
degradation beginning at 120°C in dry air. This
temperature decreases as the moisture content
increases.1
CFM is miscible with the principal organic
solvents and slightly soluble in water. It
dissolves alkaloids, cellulose acetate and
benzoate, ethyl cellulose, essential oils, fats,
halogens, methyl methacrylate, many resins,
57
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CHAPTERS: HALOGENATEDORGANIC COMPOUNDS
rubber, tars, and a wide range of common
organic compounds. Chloroform decomposes at
ordinary temperatures in sunlight in the absence
of air, and in the dark in the presence of air.
Phosgene, a very toxic chemical, is one of its
oxidative decomposition products. CFM resists
thermal decomposition at temperatures up to
about 290°C.2
CTC is the most unstable of the 33/50
cholormethanes under thermal oxidation, and
least resistant to oxidative breakdown. The
vapor decomposes and gives off toxic chemicals,
such as phosgene, when in contact with a flame
or very hot surface. Therefore, the commercial
product frequently contains added stabilizers.
CTC is miscible with many common organic
liquids and is a powerful solvent for asphalt,
bitumens, chlorinated rubber, ethyl cellulose,
fats, gums, rosin, and waxes.3
PCE is the most stable of the chlorinated
ethanes and ethylenes, requiring only small
amounts of stabilizers. PCE dissolves sulfur,
iodine, mercuric chloride, and appreciable
amounts of aluminum chloride. It is a solvent
for a variety of organic compounds as well as a
large number of substances such as fats, oils,
tars, rubber, and resins. PCE is miscible with
the chlorinated organic solvents and most other
common solvents. It resists hydrolysis at
temperatures up to 150°C, and is stable to about
500°C in the absence of catalysts, air, and
moisture. In the absence of light, PCE is
unaffected by oxygen, but under ultraviolet
radiation, in the presence of air or oxygen, PCE
undergoes auto-oxidation to trichloroacetyl
chloride.4
TCE is nonflammable under conditions of
normal use, but exhibits a flammable range when
high concentrations of vapor are mixed with air
and exposed to high-energy ignition sources. In
the absence of stabilizers, it is slowly auto-
oxidized by air to acidic and corrosive oxidation
products. Stabilizers are added to all
commercial grades. TCE is miscible with many
organic liquids and is a versatile solvent.5
TCA, also known as methyl chloroform, has
a characteristic sweet, sharp odor. TCA is
miscible with other chlorinated solvents and is
soluble in most common organic solvents. TCA
is among the least toxic of the chlorinated
solvents used in industry. It was originally
developed for industrial use as a replacement for
carbon tetrachloride because of its lower toxicity.
The use of TCA was hampered for a number of
years because of poor product stability, but the
product use experienced a rapid period of growth
once an adequate stabilization system was
developed.6
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
Just as the 33/50 halogenated organic
compounds have similar physical properties, they
also have similar health, safety, and
environmental issues associated with their
production and use. All but TCA are classified
as possible or probable human carcinogens by
EPA. All six compounds are CNS and
respiratory depressants. Exposure to all the
33/50 halogenated organic compounds except
TCA is associated with liver and kidney
problems.
The major routes of exposure to these
compounds are through inhalation or ingestion,
although dermal exposure may occur from
absorption through the skin. Air emissions
account for the largest environmental releases of
these compounds, due to their high volatility.
CTC and TCA have long atmospheric lifetimes
and contribute to ozone depletion. Land disposal
of these chemicals is prohibited under the
Hazardous and Solid Waste Amendments of
1984. The 33/50 halogenated organic
compounds are also highly mobile in soil and
groundwater and are common groundwater
contaminants. The particular issues associated
with the 33/50 halogenated organic compounds
are discussed briefly below.
Dichloromethane
Most exposure to DCM occurs via
inhalation.7 Exposure to DCM in low levels and
for short durations can cause a slight irritation of
the nose and throat.8 Exposure to DCM may
59
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PARTI; PRIORITY CHEMICALS
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CHAPTER 3: HALOGENATED ORGANIC COMPOUNDS
Tetrachloroethylene
Exposure to PCE may occur from its use in
dry cleaning applications, as a solvent, and as an
intermediate in chemical synthesis. In addition
to eye and skin inflammation from contact with
liquid PCE, inhalation of its vapor can cause
CNS depression, liver necrosis, and effects on
the lung, heart, and kidney.23 Although PCE is
not officially classified by the EPA, it is thought
to be a possible-to-probable human carcinogen
(Class C-B2).24
PCE released to the atmosphere is subject to
photo -oxidation, with estimates of degradation
time ranging from an approximate half-life of
two months to less than one hour. If PCE is
released to soil, h can evaporate into the
atmosphere and leach into ground water. If PCE
is released to surface waters, it will volatilize
rapidly. It is not expected to biodegrade,
bioconcentrate in aquatic organisms, or readily
adsorb to sediment. PCE does not significantly
hydrolyze in soil or water under normal
environmental conditions.25
Trichloroethylene
Short-term exposure to TCE has occurred
through inhalation of vapors from industrial
accidents, and through accidental ingestion or
skin contact. TCE vapor may irritate the eyes,
nose, and throat. If splashed on the skin, the
liquid may cause burning, irritation, and
damage. Repeated or prolonged skin contact
with the liquid may cause inflammation of the
skin. Short-term exposure through inhalation of
TCE causes CNS depression, nausea, dizziness,
headache, tremors, and confusion.26 Acute
inhalation exposure to high levels may cause
coma and eventual death from liver or kidney
failure.27 Extended exposure can increase the
duration and intensity of these symptoms.28 TCE
is currently being re-assessed by the EPA as to
its potential to cause cancer in humans; the most
recent judgement was that TCE is a possible-to-
probable human carcinogen (Class C-B2).29
TCE enters the atmosphere from evaporation
during production and use. Although most TCE
is released to the air, it is also found in rivers,
lakes, drinking water, soil, food, marine and
freshwater biota, and humans. TCE may enter
surface waters from direct releases or from the
atmosphere by contaminated rainfall. TCE is not
expected to persist in the open environment, but
does persist in groundwater.30 TCE is reactive in
the atmosphere under smog conditions. TCE
exhibits a moderate level of bioconcentration.31
1,1,1 -Trichloroethane
TCA is less toxic than most chlorinated
hydrocarbon solvents. It is, however, a CNS
and respiratory depressant, as well as a mucous
membrane irritant. Prolonged air exposure can
result in mild eye and respiratory tract irritation.
Physical contact with liquid TCA can cause skin
and eye irritation. Exposure to concentrations
greater than 5,000 to 10,000 ppm can be lethal.
Causes of death may include respiratory and
cardiac failure.32 TCA is not classifiable as to
human carcinogenicity (EPA Class D). There
are no data for humans and animal studies that
show evidence of carcinogenicity.33
TCA is likely to enter the environment from
air emissions or from wastewater through its
production or use. TCA is fairly stable in the
atmosphere and can be transported long
distances. TCA slowly degrades principally by
reaction with hydroxyl radicals and has a half-
life of six months to 25 years. Because of its
long atmospheric half-life, TCA concentrations
in the stratosphere are increasing by 12 to 17
percent/year.34 As an ozone-depleting substance,
phase-out of TCA production is mandated in the
U.S. by the end of 1995.
Releases of TCA to surface water will rapidly
evaporate to the atmosphere. TCA is not
adsorbed strongly to soil and may leach to
ground water. Major human exposure is from air
and drinking water.35
INDUSTRY PROFILE
Four companies at six locations in the U.S.
are major producers of the 33/50 halogenated
compounds. Table 3.2 lists the producers of
these products, the manufacturing processes they
employ, and their annual production capacities.
61
-------
PARTI; PRIORITY CHEMICALS
TABLE 3.3 PRICES OF 33/50 HALOGENATED COMPOUNDS
Chemical
CTC
CFM
DCM
PCE
TCA
TCE
Historical
($/lb)a
High
0.25
0.46
0.32
0.31
0.64
0.45
Low
0.085
0.17
0.07
0.095
0.09
0.105
Current
($/lb)b
0.215
0.44 to 0.46
0.29
0.29
0.64
0.45
Source:
Chemical Marketing Reporter
* Historical price range is from 1952 to 1994, except CTC, which is from 1952 to 1989
b Current price for industrial grade, bulk quantity, as of week ending January 28, 1994
co-products are also produced at one facility by
the oxychlorination of ethylene dichloride
(EDC). One facility uses the chlorination of
EDC to produce TCE. These production
processes are described below.
Hydrochlorination of Methanol
In the U.S. the predominant process of
industrial production of DCM and CFM is the
hydrochlorination of methanol. The process
begins with the preliminary reaction of
approximately equimolar ratios of hydrogen
chloride and methanol, with the aid of a catalyst,
to produce methyl chloride. This reaction is
carried out in the vapor phase, where the two
components are passed through a preheater at
180°C. The gas mixture is then passed through a
converter, which is maintained at atmospheric
pressure and a temperature of 340 to 350°C.
The methyl chloride produced is then fed to
reactors, where it is combined with chlorine to
produce DCM, CFM, and CTC. Condensers
are used to collect and purify the hot reaction
gases, The crude CTC that is produced from
this process is used as feed in the hydrocarbon
chlorinolysis process to produce CTC and
PCE.43
Direct Chlorination of Methane
Direct chlorination of methane is an
irreversible process that involves directly
reacting chlorine (C12) with excess methane at a
high temperature (approximately 485 to 510°C).
Elevated temperatures are required to produce
dissociation of chlorine and initiate the
chlorination reaction. Methyl chloride, DCM,
and CFM are the first three products of
chlorination; each is subject to further
chlorination to the succeeding heavier
chloromethane compound. The raw material
flow rates, including the initial concentration of
chlorine in the feed, and the temperature, may be
controlled to produce the particular
chloromethane desired.
The effluent from the reactor contains
unreacted methane and hydrogen chloride, which
are usually separated from the chloromethanes in
the scrubbing stage. The scrubber employs a
refrigerated mixture of higher chloromethanes,
in which the chloromethanes are only slightly
soluble. The methane is freed from the acid via
water scrubbing, and is recycled back to the
chlorinator. The chloromethane co-products are
then washed, scrubbed with alkali, dried, and
passed to a sequence of fractionating columns.44
64
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CHAPTER 3: HALOGENATED ORGANIC COMPOUNDS
Tht t ">Jected demand for these compounds, the
market trends associated with their production
and use, and the prices of the 33/50 halogenated
chemicals are also presented below.
The demand for most of the 33/50 chemicals
has decreased in recent years, due to concern
about their health and environmental effects.
Market Trends
Production capacity for most of the 33/50
halogenated compounds has decreased in recent
years, owing to health, safety, and environmental
issues. Capacity in 1992 exceeded the projected
1992 demand for each of these compounds
except CTC. CTC'capacity was reduced by 340
million pounds in 1991 when Akzo American in
LeMoyne, Alabama and Dow Chemical in
Pittsburgh, California shut down their CTC
production processes.36
The size of the DCM market declined 3.1
percent per year from 1982 to 1991, with this
negative growth expected to continue at -3.0
percent: per year through 1996. Industry
representatives believe that available substitutes
are generally less cost-effective, but a revised
permissible exposure limit proposed by OSHA
could accelerate declines in some segments,
particularly in paint stripper applications.37
CFM is the only 33/50 chlorinated organic
compound for which a consistent growth of
demand is projected. Historically (1982 to
1991), CFM demand has increased by 5.2
percent per year. Future growth is expected to
be 2.5 percent per year.38 Growth is projected
because CFM is a feed material for
hydrochlorofluorocarbon (HCFC-22) which is
expected to remain a viable chlorofluorocarbon
(CFC) substitute for the next decade. EPA plans
to phase-out most HCFCs by 2005, with
exceptions made for the servicing of existing
equipment until 2015.
CTC consumption declined 0.7 percent per
year between 1978 and 1988 and was projected
to decline three percent per year through 1993.39
Since the phase-out of CTC production in the
U.S. has been accelerated to 1995, the decline in
consumption may be more rapid.
The demand for PCE has declined in recent
years, due to its use as a feedstock for CFC-113.
Market sources predict that demand should
remain fairly stable through the mid 1990s, when
PCE use should increase from large-scale
production of CFC replacement compounds.
Despite new restrictions, PCE is also expected to
maintain its strong position as a solvent in the dry
cleaning industry.40
The demand for TCE decreased an average of
1.9 percent per year between 1982 and 1991.
Future demand is expected to decrease 2.6
percent per year through 1996. Use of TCE as a
vapor degreaser is expected to continue its
downward trend, with demand falling at the rate
of two to three percent per year. If TCE
becomes a potential feedstock for CFC
alternatives, however, it could begin to
experience renewed growth.41
The demand for TCA increased 0.8 percent
per year between 1982 and 1991, but is expected
to decrease until its phase-out at the end of
1995.42
Price of the 33/50 Halogenated
Compounds
The price of the 33/50 halogenated
compounds has fluctuated somewhat over the
years. Table 3.3 presents the historical price
range and current prices. Current prices for
each of the compounds are at, or near, their
historical highs.
PRODUCTION PROCESSES
CFM and DCM are produced as co-products
by the direct chlorination of methane at one
facility, and by the hydrochlorination of
methanol at five facilities in the U.S. CTC is
produced as a by-product of the
hydrochlorination-of-methanol process at three of
these facilities, and is used as feed to the
hydrocarbon-chlorinolysis process.
Hydrocarbon-chlorinolysis is used to produce
CTC and PCE as co-products. PCE and TCE
63
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PART 1: PRIORITY CHEMICALS
The 33/50 halogenated organic chemicals
alone contributed almost 14 percent of all TRI
air emissions in 1991. The chemicals and allied
products industry was the largest reported
emitter of these chemicals, contributing almost
16 percent of the total.
Environmental Releases from Production
Air emissions of halogenated organic
compounds from production processes can
originate from the intermittent or continuous
purging of inert gases from reactor vessels,
drying beds, finishing columns, and other
process vessels. Fugitive air emissions can result
when process fluids leak from plant equipment
such as pumps, compressors, and process valves.
Air emissions from storage and handling
operations also occur at production facilities.
Other sources of environmental releases or
transfers, include the following:
• wastewater discharges directly from the plant
into rivers, streams or other bodies of water,
or transfers to a POTW;
» on-site release to landfills, surface
impoundments, land treatment, or another
mode of land disposal;
• disposal of wastes by deep well injection; and
• transfers of wastes to off-site facilities for
treatment, storage or disposal.
The environmental releases and transfers of
the 33/50 halogenated organic compounds from
the major producers identified in Table 3.2 were
retrieved from the 1991 TRI data. The data are
presented in Table 3.4. Many of the facilities
reported multiple SIC codes on one form,
indicating the data may include releases from
internal use of the chemicals after production.
Distribution of Environmental Releases by
Industry Group
Each of the 33/50 halogenated organic
chemicals, except CTC, was within the top 50
chemicals for TRI total releases and transfers
in 1991. Table 3.5 lists their total releases and
transfers and relative rank. TCA contributed
the largest percentage of total emissions for
this chemical class, accounting for 45 percent
of the total releases and transfers of the 33/50
halogenated organic chemicals. Combined,
the 33/50 halogenated organics accounted for
almost 14 percent of all TRI air emissions in
1991.48
Releases and transfers of the 33/50
halogenated organics were fairly widely
distributed across industry groups in 1991.
Table 3.6 lists the top eight industries that
emitted the largest quantities of these chemicals
and their total reported releases and transfers.
The chemicals and allied products industry
reported the largest total emissions of the 33/50
halogenated organics, followed by rubber and
plastics products manufacturers, and the
transportation industry. Releases from the
chemicals and allied product result from
production of the compounds and their use as
chemical intermediates, as solvents, and as
chemical processing aids. DCM is the
halogenated organic released in the largest
quantity by the chemicals and alUed products
industry, which includes manufacturers of
plastic materials and resins. DCM is used to
dissolve triacetate polymer flake to form a
liquid extmdable polymer. It is also used as
a solvent in the polymerization reaction to
form polycarbonate resin. A major source
of unintended production and release of CFM
is the use of chlorine and hypochlorite to
bleach virgin pulp in the paper industry. The
use of chlorine and hypochlorite to remove
unwanted dyes from recycled paper also
generates chloroform.49
66
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CHAPTER 3: HALOGENATED ORGANIC COMPOUNDS
Hydrocarbon Chlorinolysis
Hydrocarbon chlorinolysis involves the
breakage of a carbon-carbon bond when a
chlorinated hydrocarbon or hydrocarbon is
reacted with excess chlorine at a high
temperature, usually 400 to 700°C. Since fully-
chlorinated hydrocarbons, with fewer carbon
atoms than the starting material, are obtained,
the process is frequently referred to as
perchlorination.
Propane, propylene, acetylene, naphthalene,
ethylene dichloride, and crude CTC are used as
feedstocks in the hydrocarbon-chlorinolysis
process. The hydrocarbon feed, fresh C12, and
recycled C12 are fed to a vaporizer, where they
are mixed with recycled chlorides. The mixed
gases are then fed to a refractor-lined reactor,
which operates at high temperatures and at
atmospheric pressure. After startup, the reaction
is self-sustaining. The CTC/PCE ratio is
controlled by the diluent action of the recycled
chlorides. Effluent from the reactor consists
mainly of CTC, PCE, hydrogen chloride (HC1),
and excess chlorine, along with unreacted
hydrocarbons. The hot effluent gas is quenched
and HC1 and C12 are removed. The liquid stream
from the quenched gas is separated into CTC and
PCE by distillation. Heavy ends from the
distillation column are recycled back to the feed
tank.45
Chlorination of Ethylene Dichloride
Dow Chemical in Freeport, Texas, uses the
Chlorination of EDC to produce TCE. EDC is
first produced by the Chlorination of ethylene.
The EDC is further chlorinated in an exothermic
reaction carried out in the presence of a catalyst
at 280 to 450°C. Temperature in the reactor is
controlled by a fluidized bed, a molten salt bath,
or the addition of an inert material. PCE can
also be produced by the Chlorination of EDC as a
co-product by varying reaction conditions.
Oxychlorination of Ethylene Dichloride
PPG Industries employs the oxychlorination
of EDC to produce both PCE and TCE. The
product mix can be varied by adjusting the mole-
feed ratios of EDC, Cla, and oxygen. The
single-stage reaction occurs in the presence
of a catalyst, at a temperature around 430°C,
and a pressure slightly above one atmosphere.
The build-up of a great amount of hydrogen
chloride is avoided by concomitantly operating
HC1 oxidation. The reaction involves the
simultaneous oxychlorination/
dehydrochlorination using chlorine or
anhydrous hydrogen chloride as the chlorine
46
source.
Production of TCA
The most widely used process for producing
TCA involves the dehydrochlorination of EDC to
vinyl chloride, which is then hydrochlorinated to
1,1 -dichloroethane. The 1,1 -dichloroethane is
thermally or photochemically chlorinated to
produce TCA. In another important process,
hydrogen chloride is added to 1,1-
dichloroethylene in the presence of an iron
chloride catalyst to produce TCA.
When vinyl chloride is used, a preparatory
step must be performed to break the double bond
while maintaining all the chlorine atoms on one
carbon. This is usually accomplished through
hydrochlorination, using hydrogen chloride.
Hydrochlorination can also be used with a
vinylidene-chloride feed, which results in the
direct production of TCA. Typical reaction
temperatures for the thermal Chlorination range
from 370 to 430°C. This is a highly exothermic
reaction, with much of the liberated energy being
taken out as sensible heat along with the
products.47
ENVIRONMENTAL RELEASES OF 33/50
HALOGENATED COMPOUNDS
Environmental releases of the 33/50
halogenated organics occur from their
production, use, and disposal. The discussion
below presents the types of releases and transfers
that occur from production facilities, the releases
and transfers reported by the major producers of
these chemicals in the 1991 TRI, and the
distribution of environmental releases by industry
group.
65
-------
PARTI; PRIORITY CHEMICALS
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CHAPTER 3: HALOGENATED ORGANIC COMPOUNDS
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70
-------
CHAPTER 3: HALOGENATED ORGANIC COMPOUNDS
TABLE 3.5 TOTAL RELEASES AND TRANSFERS OF 33/50 HALOGENATED ORGANIC
COMPOUNDS
Chemical
CTC
CFM
DCM
PCE
TCA
TCE
TOTAL
Releases and Transfers
(Ibs/yr)
2,575,457
22,576,422
94,786,380
20,797,397
145,996,101
38,001,222
324,732,979
TRIRank
73
36
14
38
10
26
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc., Inc.
U.S., EPA, Office of Pollution Prevention and Toxics, 33/50 Program Office
USES OF THE HALOGENATED ORGANIC
COMPOUNDS
The six 33/50 halogenated organic chemicals
are widely used as cleaning solvents, as chemical
intermediates in the manufacture of
fluorocarbons and other chemicals, and as
components of consumer products. The uses are
illustrated in a chemical-use tree diagram shown
on Figure 3.1.50
Three use clusters of the 33/50 halogenated
organic chemicals were selected for substitutes
evaluation: metal and parts degreasing, dry
cleaning, and paint stripping. Not only do these
use clusters represent three of the largest uses
of the 33/50 halogenated organics, they also
represent applications where there is significant
risk of release or exposure.
To illustrate the potential for the increase in
production of one compound as the use of
another decreases, the chemical-use tree diagram
also shows production processes and co-
products. For example, CTC production has
dropped significantly since the
chlorofluorocarbon restrictions took effect,
causing those who co-produce CTC and PCE to
swing their production to PCE.51
The numbers along each branch of the
chemical-use tree are weight fractions of the
usage of the chemical or product in the first box
to produce the chemical or product in the second
box. For example, in Figure 3.1, 98 percent of
the chloroform produced is used to manufacture
fluorocarbon-22; 70 percent of the fluorocarbon-
22 produced is used as refrigerants. Where there
is a box that is divided, the chemicals or products
are co-products. For example, CFM and DCM
are co-products of methanol hydrochlorination.
Metal and parts degreasing, dry cleaning, and
paint stripping applications of the 33/50
halogenated organic compounds have been
selected as priority use clusters for substitutes
evaluation. These use clusters were selected
based on the following criteria: 1) the relative
magnitude of the product or use; 2) the status of
the product or use (products with a federally
69
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PARTI; PRIORITY CHEMICALS
mandated phase-out schedule were not selected);
and 3) the qualitative risk of release or exposure
from the product or use. These priority use
clusters, and some of the other major products
and uses of the chlorinated solvents, are
discussed briefly below.
Fluorocarbon Production
The largest single use of the 33/50
halogenated organic compounds is as a precursor
for the manufacture of CFCs and HCFCs.
CTC, CFM, and PCE are all used as chemical
intermediates in the production of CFCs
(Fluorocarbons-11, -12 and -113) and HCFCs
(Fluorocarbon-22). Based on the chemical-use
tree diagram and the 1991 demand data, this use
consumed approximately 845 million pounds of
33/50 halogenated organic compounds, or
roughly 37 percent of these chemicals consumed
that year. TCE is also being evaluated as a
precursor in the production of CFC replacement
compounds, such as HFC-134a and HCFC-123.
Although the production of CFCs and HCFCs
is the most significant use in terms of mass, this
use was not selected for substitute evaluation,
since these compounds are scheduled for phase-
out, and significant progress has been made in
identifying and implementing effective
substitutes. The Montreal Protocol and the
Clean Air Act Amendments of 1990 calls for a
phase-out of CTC and ozone-depleting CFCs by
the year 2000, and the elimination of HCFCs by
2030. The U.S. has accelerated this phase-out
schedule and ordered CTC and CFC
manufacturers to halt production by the end of
1995. In addition, EPA proposes phasing-out the
HCFCs with the highest depletion potential by
2005, with exceptions made for the servicing of
equipment until 2015.
Metal and Parts Degreasing
Based on the chemical-use tree and 1991
demand data, approximately 535 million pounds
of the 33/50 halogenated organics, including
DCM, PCE, TCE, and TCA were consumed in
metal and parts degreasing applications in 1991.
This represents approximately 24 percent of the
total consumed that year, indicating that metal
cleaning is the second largest use by weight of
these chemicals.
Chlorinated solvents have been popular
industrial solvents since they were first
produced. However, in recent years, with the
increased awareness of the health, safety, and
environmental issues surrounding their use,
alternatives to chlorinated-solvent metal cleaning
have been identified. Several viable alternatives
exist, and substantial progress is being made in
pollution prevention in metal and parts cleaning
by use of safe substitutes. Safe substitutes for
33/50 halogenated compounds used in degreasing
applications are evaluated in Chapter 9.
Dry Cleaning
Both PCE and TCA are used to dry clean
fabrics, although TCA use represents only a
small fraction of the 33/50 halogenated organic
compounds consumed in dry cleaning operations.
PCE is the solvent of choice in the U.S. for dry
cleaning fabrics, evidenced by its market share
for this process (more than 75 percent). The
effects of dry cleaning on the environment are
evidenced by increased concentrations of PCE in
ambient air in urban areas. Alternatives to the
dry cleaning process and safe substitute dry
cleaning solvents are evaluated in Chapter 10.
Consumer Products
DCM and TCA are used in consumer
products such as paint stripping formulations and
aerosols. Paint stripping and aerosol applications
of these two chemicals account for 12 percent of
their use. Two of the significant features of
these applications are the following: 1) all DCM
and TCA consumed in these products are
released to the environment, primarily through
volatilization; and 2) consumers are exposed to
the chemicals during the application and use of
the products.
DCM and TCA use in aerosols has decreased
in recent years, as different propellants, such as
carbon dioxide, have come into prevalent use.
72
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CHAPTER 3; HALOGENATED ORGANIC COMPOUNDS
HIRFPT PHI ORI NATION
OF METHANE OR
HYDROCHLORINATION
DCM —
^
•31*
.08
.16^
.14
.11fc
.11^
.04
.98
PAINT STRIPPER
Y/////MKno\* '//////
//////, AEROSOLS //////;
IIRtTMAKIF PTIAM Rl DM/IMA AOFMT
MJARMAOCimPAl C
' MCTAI r»R DARTC ncRRCAQiun V
VvvvvvvvvvvvvvvvvV
ELECTRONICS
.. —
Cl 1 IDDOOARPrtM 99
POLYCARBONATE
TRIACETATE RBER
.70
FLUOROPOLYMERS
FLUOROCARBONS
11 and 12
HEAT TRANSFER
FLUOROCARBON F-113
CHLORINATION
OF EDC OR
OXYCHLORINATION
OF EDC
VAPOR DECREASING
CHEMICAL INTERMEDIATE AND MISCELLANEOUS USE
VAPOR DEGREASING
META OR PARTS DEGREASIN
COLD CLEANING
NEOPRENE ADHESIVES
COATINGS AND INKS
DRYCLEANING AND TEXTILE PROCESSING
FIGURE 3.1 CHLORINATED ORGANICS
NOTE: Shaded regions identify use clusters associated with the halogenated organic chemicals
Reliable data were not available to estimate weight fractions along some branches of the chemical-use tree
71
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PARTI; PRIORITY CHEMICALS
ENDNOTES
1 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
Vol. 5.
2 Ibid.
3 Ibid.
4 Ibid.
5 Ibid.
6 Ibid.
7 International Programme on Chemical Safety, Methylene Chloride, Environmental Health
Criteria 32, (Geneva World Health Organization, 1990).
8 Hampshire Research Associates, Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, 1989).
9 International Programme on Chemical Safety, Methylene Chloride, Environmental Health
Criteria 32, (Geneva World Health Organization, 1990).
10 Hampshire Research Associates, Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, 1989).
11 "VicMoTometiiane," Integrated Risk Management System, 1994.
12 International Programme on Chemical Safety, Methylene Chloride, Environmental Health
Criteria 32, (Geneva World Health Organization, 1990).
13 Ibid.
14 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
Vol. 5.
IS it
Chloroform," Hazardous Substances Data Bank, August 23, 1990.
16 "Chloroform," Integrated Risk Information System, 1994.
"Chloroform," Hazardous Substances Data Bank, August 23, 1990.
18 Ibid.
"Carton Tetrachloride: Chemical Information Sheet, Illinois Environmental Protection Agency
Office of Chemical Safety, February 1989.
20 "Carbon Tetrachloride," Integrated Risk Information System, 1994.
74
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CHAPTER 3: HALOGENATED ORGANIC COMPOUNDS
Also, use of TCA in general is declining, paint strippers in industrial applications.
because producers are anticipating the phase-out Alternative chemical formulations are beginning
of this chemical as an ozone-depleting substance. to be employed in certain applications in the
New paint stripping methods, such as blasting consumer market. Chapter 11 presents an
methods, heat technologies, and alkaline or acid evaluation of safe substitutes for DCM-based
strippers, are beginning to replace DCM-based paint strippers.
13
-------
PARTI: PRIORITY CHEMICALS
44 Ibid.
45 Survey of Carbon Tetrachloride Emission Sources, US EPA, Pub. No. EPA 450/3-85-018,
(Research Triangle Park, NC, July 1985).
46 Survey of Perchloroethylene Emission Sources, US EPA, (Research Triangle Park NC
July 1985).
47 Encyclopedia of Chemical Processing and Design, Vol. 8.
48 7997 Toxics Release Inventory, Public Data Release, US EPA, Office of Pollution Prevention
and Toxics, May 1993.
49 Timothy E. McKinney, "Alternative Chemicals Gain Popularity for Bleaching of Woodfree
Furnishes," Pulp and Paper, March 1992.
50 Sources for Figure 3.1:
"Chemical Profile: Methylene Chloride," Chemical Marketing Reporter, March 2, 1992.
"Chemical Profile: Chloroform," Chemical Marketing Reporter, February 24, 1992.
"Chemical Profile: Carbon Tetrachloride," Chemical Marketing Reporter, February 17, 1992.
"Chemical Profile: 1,1,1-Trichloroethane," Chemical Marketing Reporter, January 21, 1992.
"Chemical Profile: Trichloroethylene," Chemical Marketing Reporter, Februarys, 1992.
"Chemical Profile: Perchloroethylene," Chemical Marketing Reporter, January 20, 1992.
Ralph C. Downing, Fluorocarbon Refrigerants Handbook, (Englewood Cliffs, NJ: Prentice Hall
1988).
Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley 1993)
Vol. 5.
51 «
Chemical Profile: Perchloroethylene," Chemical Marketing Reporter, January 10, 1992.
76
-------
CHAPTERS; HALOGENATEDORGANIC COMPOUNDS
21 Carbon Tetrachloride: Chemical Information Sheet, Illinois Environmental Protection Agency,
Office of Chemical Safety, February 1989.
22 Ibid.
"Tetrachloroethylene," Hazardous Substances Data Bank, October 23, 1990.
23 ••'
24 Superfund Health Risk Technical Support Center, April 1994.
25 "Tetrachloroethylene," Hazardous Substances Data Bank, October 23, 1990.
26
Trichloroethylene: Chemical Information Sheet, Illinois Environmental Protection Agency,
December 1986.
27 n
Trichloroethylene," Hazardous Substances Data Bank, 1994.
28
Trichloroethylene: Chemical Information Sheet, Illinois Environmental Protection Agency,
December 1986.
29
Superfund Health Risk Technical Support Center, April 1994.
30 Trichloroethylene: Chemical Information Sheet, Illinois Environmental Protection Agency,
December 1986.
31 "Trichloroethylene," Hazardous Substances Data Bank, 1994.
32 " 1,1,1 - Trichloroethane," Hazardous Substances Data Bank, October 22, 1990.
33 "1,1,1 - Trichloroethane," Integrated Risk Information System, 1994.
34" 1,1,1 - Trichloroethane," Hazardous Substances Data Bank, October 22, 1990.
35 Ibid.
'Chemical Profile: Carbon Tetrachloride," Chemical Marketing Reporter, February 17, 1992.
36 ti t
37 "Chemical Profile: Methylene Chloride," Chemical Marketing Reporter, March 2, 1992.
"Chemical Profile: Chloroform," Chemical Marketing Reporter, February 24, 1992.
38 i
39
40 n
41
42
43
Vol. 5.
"Chemical Profile: Carbon Tetrachloride," Chemical Marketing Reporter, February 17, 1992.
Chemical Profile: Perchloroethylene," Chemical Marketing Reporter, January 20, 1992.
"Chemical Profile: Trichloroethylene," Chemical Marketing Reporter, February 3, 1992.
"Chemical Profile: Trichloroethane," Chemical Marketing Reporter, January 27, 1992.
Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
75
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PART I: PRIORITY CHEMICALS
TABLE 4.1 SELECTED PROPERTIES OF HYDROGEN CYANIDE AND SODIUM CYANIDE
Property "
Chemical formula
CAS No.
Molecular Weight
Boiling Point, at 101.3 kPa, °C
Melting Point, °C
Specific Gravity, at 20°C
Viscosity, at 30°C, cP
Heat of Vaporization, at 101.3 kPa, kJ/mol
Heat of Capacity, at 25°C, kJ/kgK
Heat of Fusion, kj/kg
Vapor Pressure, at 20°C, kPa
Flash point, °C
Critical temperature, °C
Critical pressure, MPa
Hydrogen Cyanide
HCN
74-90-8
27.03
25.7
-13.24
0.829"
0.2014"
25.20
2.63
310
83
-17.8
183.5
5
Sodium Cyanide
NaCN
143-33-9
49.02
1500
+563.7
1.60
4
156.37
1.402
314
0.4452C
N/A
N/A
N/A
Sources:
Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed.
Ullmann's Encyclopedia of Industrial Chemistry, 5th ed.
' for 60.237 percent HCN
b at 20.2°C
c Vapor Pressure at 900°C
N/A: Not Available
metabolic system and causing rapid death.
Within seconds to minutes of inhalation or
ingestion of cyanide, symptoms such as
giddiness, abnormally rapid or deep breathing,
shortness of breath, headache, palpitation,
cyanosis, and unconsciousness occur.
Overexposure may produce sudden loss of
consciousness, convulsions, and prompt death
from respiratory arrest. It is also possible for
cyanide to cause blindness and damage to optic
nerves and the retina.4
The 33/50 cyanide compounds are acutely
poisonous, interfering with the metabolic system
and causing rapid death. Major sources of
cyanide releases to the environment are the
metal finishing industries, iron and steel mills,
organic chemical industries, and vehicle
exhaust.
Major sources of cyanide releases to water
include the metal finishing industries, iron and
steel mills, and organic chemical industries.
Vehicle exhaust releases cyanide to the air. The
primary releases to the soil appear to be from
cyanide-containing waste landfills and the use of
cyanide-containing road salts. In water and soil
the fate of cyanide is predicted to be pH-
dependent. It may occur in the form of
hydrogen cyanide, alkali metal salts, or immobile
metallocyanide complexes. In subsurface soils,
low concentrations of cyanide will probably
biodegrade. Cyanide may also leach into
groundwater. Bacteria and protozoa may
degrade cyanide by converting it to carbon
dioxide and ammonia. Cyanide is converted to
cyanate during chlorination of water supplies.5
Most cyanide in the atmosphere exists as
hydrogen cyanide gas, but small amounts of
metal cyanides may be present as paniculate
matter. Hydrogen cyanide reacts with
78
-------
CHAPTER 4
Hydrogen cyanide and cyanide compounds
are the fourth class of chemicals included in
EPA's 33/50 Program. The 33/50 cyanide
compounds are those where a formal dissociation
of the compounds may occur to yield the cyanide
moiety CN".1 Cyanide compounds are reported
in the 1991 TRI under the aggregate heading of
"cyanide compounds," except hydrogen cyanide,
which is reported separately.
Cyanides are produced by industry in many
different forms. Sodium cyanide and hydrogen
cyanide are the two most common industrial
cyanide compounds and are discussed in the most
detail in this section.
PHYSICAL PROPERTIES
Selected physical properties and the chemical
formulae of hydrogen cyanide and sodium
cyanide are shown in Table 4.1. The physical
characteristics are summarized below.
Hydrogen cyanide (HCN) is a liquid below
26.5°C, with a characteristic odor of bitter
almonds. It is a very weak acid compound that
is misdble with water and alcohol but only
slightly soluble in ether.2 It is normally not
considered corrosive, but will corrode steel
under certain conditions. Hydrogen cyanide
burns with a very hot flame in the presence of
oxygen or air.
Sodium cyanide (NaCN) is an alkali-metal
cyanide. It is a colorless, hygroscopic salt that
has a slight odor of hydrogen cyanide (bitter
almonds) and ammonia in moist air. It is a white
crystalline solid at room temperature. In the
absence of air, carbon dioxide, and moisture
sodium cyanide is stable at fairly high
temperature and can be stored indefinitely. It is
fairly soluble hi water where it will form sodium
salt hydrates. Sodium cyanide is totally
decomposed to hydrogen cyanide by the actions
of strong acids. Molten sodium cyanide reacts
violently with strong oxidizing agents such as
nitrates and sodium cyanide chlorates.3
Exposure to cyanides camsccur by inhalation,
ingestion, or absorption through skin and
mucosal surfaces. Cyanides, such as hydrogen
cyanide, potassium cyanide, and sodium cyanide,
are acutely poisonous, interfering with the
77
-------
PART I: PRIORITY CHEMICALS
TABLE 4.3 SODIUM CYANIDE PRODUCTION CAPACITY
Producer
Cyanco Co./Alta Gold
Degussa Corp.
Du Pont Co.
Du Pont Co.
FMC Corp.
Sterling Chemical
Location
Winnemuca, NV
Mobile, AL
Memphis, TN
Texas City, TX
Green River, WY
Texas City, TX
TOTAL
Capacity
(million Ibs/yr)
30
60
250
100
60
N/A
500
Sources:
Capacity: Chemical Marketing Reporter, February 11, 1991
Companies: 1992 Directory of Chemical Producers: United States of America, SRI International
N/A: Not Available
cyanide plants or increase their capacities
because gold prices were high. When the price
of gold subsequently dropped from $450 per
ounce in 1988 to $366 per ounce in February of
1991, the world-wide sodium cyanide market
was depressed by oversupply and slowing
growth. Projections are for continued
overcapacity for several years; operating rates
are predicted to be at 55 to 70 percent capacity.10
Price of Cyanide Compounds
Table 4.4 presents the historical price range
of hydrogen cyanide and the current prices for
both hydrogen cyanide and sodium cyanide. The
price of hydrogen cyanide is at its historical high.
The price of sodium cyanide has decreased in
recent years due to oversupply and slowing
growth.
PRODUCTION PROCESSES
Hydrogen cyanide is produced commercially
by the Andrussow process. Sodium cyanide is
manufactured from hydrogen cyanide by the
neutralization process. These processes are
discussed below.
Production of Hydrogen Cyanide
The Andrussow process has been the most
widely used process for producing hydrogen
cyanide since its introduction in 1964. Here,
methane, ammonia, and air (oxygen) are reacted
over a platinum catalyst at 1,000 to 1,200°C.
The reaction is extremely rapid, but the pathway
to formation of hydrogen cyanide is not direct.
Because the hydrogen cyanide will tend to
polymerize under high pH conditions, sulfuric
acid is added to the process to maintain a low
pH. Various absorption and distillation steps are
utilized in order to process the various streams
for recovery of ammonia reagent.
A disadvantage of this process is that the
offgas stream from the reactor contains dilute
hydrogen cyanide gas. Therefore, recovery
equipment must be large enough to process large
volumes of gas. Also, the unreacted ammonia
concentration is great enough that it must be
recycled or recovered. Positive aspects of the
process include the fact that the raw materials
are relatively cheap, and the overall catalyst
costs are low.11 Hydrogen cyanide is also
produced as a by-product of the ammoxidation of
propylene during the production of vinyl
cyanide.12
80
-------
CHAPTER 4; HYDROGEN CYANIDE AND CYANIDE COMPOUNDS
photochemically generated hydroxyl radicals
at a very slow rate with a half-life of
approximately 334 days. It is also expected
to be resistant to direct photolysis. Because
of this slow rate of degradation, hydrogen
cyanide has the potential to be transported
over long distances before being removed by
physical or chemical processes.6 Cyanide,
however, is not accumulated or stored in any
mammalian species, and hydrogen cyanide is
not strongly partitioned into the sediments
or suspended adsorbents, due to its high
solubility in water.7
INDUSTRY PROFILE
Hydrogen cyanide is produced by nine
companies at 13 locations in the U.S. Sodium
cyanide can be produced by four companies at
five locations. Tables 4.2 and 4.3 identity the
current producers and production capacities of
hydrogen cyanide and sodium cyanide,
respectively. The market trends associated with
the production and use of the 33/50 cyanide
compounds and their prices are presented below.
Market Trends
The projected growth rate for hydrogen
cyanide is three to four percent per year through
1997. Hydrogen cyanide is seeing an increased
demand because of strong demand for nylon and
methyl methacrylate (MMA), two products
manufactured using hydrogen cyanide. In 1990,
market sources indicated that production of the
hydrogen cyanide end products, particularly
MM A, was limited because the hydrogen
cyanide capacity had not kept up with the
demand.8 Conversely, increasing uses of water-
borne lacquer systems is expected to decrease the
demand for MMA-based acrylic lacquers, thus
decreasing the demand for HCN.9
One of the major uses of sodium cyanide is to
leach gold from its ore. Since high gold prices
make it more economically feasible to mine gold,
the demand for sodium cyanide is closely linked
to the price of gold. In the mid to late 1980s,
manufacturers made plans to open new sodium
TABLE 4.2 HYDROGEN CYANIDE PRODUCTION CAPACITY
Producer
American Cyanamid Co.
BP Chemicals, Inc.
BP Chemicals, Inc.
Ciba-Geigy
Degussa/Du Pont Co.
Dow Chemical U.S.A.
Du Pont Co.
Du Pont Co.
Du Pont Co.
Du Pont Co.
Monsanto Co.
Rohm and Haas Co.
Sterling Chemicals, Inc.
Location
Westwego, LA
Port Lavaca, TX
Lima, OH
St. Gabriel, LA
Theodore, AL
Freeport, TX
Beaumont, TX
Memphis, TN
Orange, TX
Victoria, TX
Alvin, TX
Deer Park, TX
Texas City, TX
TOTAL
Capacity
(million Ibs/yr)
60
70
35
90
55
20
60
200
320
300
60
200
90
1,560
Source:
Chemical Marketing Reporter, May 24, 1993
79
-------
PART I: PRIORITY CHEMICALS
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CHAPTER 4: HYDROGEN CYANIDE AND CYANIDE COMPOUNDS
TABLE 4.4 PRICES OF HYDROGEN CYANIDE AND SODIUM CYANIDE
Chemical
Hydrogen Cyanide
Sodium Cyanide
Historical Price ($/lb)a
High
0.60
N/A
Low
0.115
N/A
Current Price
($/lb)b
0.60
0.60
Source:
Chemical Marketing Reporter
* Historical price range is from 1957 to 1990
b Current price for industrial grade, bulk quantity, as of week ending February 7, 1994
N/A: Not Available
Production of Sodium Cyanide
The manufacture of sodium cyanide is known
as the neutralization process or wet process.
Here, purified anhydrous liquid hydrogen
cyanide (hydrocyanic acid), sometimes in vapor
form, Is reacted with 50 percent sodium
hydroxide solution (caustic soda). The utmost
purity of the reactants in turn yields 99 percent
sodium cyanide.13
Large commercial plants use purified
hydrogen cyanide from the Andrussow process to
manufacture sodium cyanide. The downstream
processing steps after the neutralization step
include evaporation, for removal of water, and
crystallization. As in the hydrogen cyanide
process, it is crucial to avoid the polymerization
of the hydrogen cyanide reagent, which can
occur under high pH conditions.
The neutralization process is not energy
intensive except for the heat needed to evaporate
the water in the sodium hydroxide solution and
formed in the reaction. Waste from the process
contains 10 to 100 ppm of sodium cyanide and
must be treated.
ENVIRONMENTAL RELEASES FROM
PRODUCTION
Environmental releases of the 33/50 cyanide
compounds occur from their production, use,
and disposal. The types of releases and transfers
that may occur from production facilities, the
releases and transfers reported by the major
producers of these chemicals in the 1991 TRI,
and the distribution of environmental releases by
industry group are presented below.
In 1991, the chemicals and allied products
industry contributed almost 78 percent of the
total reported releases and transfers of both
hydrogen cyanide and cyanide compounds. In
this industry, releases occur from the
manufacture of cyanides and from their use as
chemical intermediates in the production of
plastics and resins and other chemical products.
Electroplating, another use of cyanide
compounds, and plastics and reins were selected
for substitutes evaluation.
Environmental Releases from Production
Facilities
The environmental releases and transfers of
the 33/50 cyanide compounds from the major
producers identified in Tables 4.2 and 4.3 were
retrieved from the 1991 TRI data. The data are
presented in Table 4.5. Some of the facilities
reported multiple SIC codes on one form,
indicating the data may include releases from
internal use of the chemicals after production.
Facilities that use hydrogen cyanide as a
chemical intermediate often produce their own
81
-------
PART I: PRIORITY CHEMICALS
TABLE 4.6 TOTAL RELEASES AND TRANSFERS OF 33/50 CYANIDES
Chemical
Cyanide Compounds
Hydrogen Cyanide
TOTAL
Releases and Transfers (Ibs/yr)
5,635,763
2,210,281
7,846,044
TRIRank
53*
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc., Inc.
U.S., EPA, Office of Pollution Prevention and Toxics, 33/50 Program Office
* TRI rank for hydrogen cyanide and cyanide compounds combined
TABLE 4.7 TOP INDUSTRIES FOR TOTAL TRI RELEASES AND TRANSFERS OF 33/50
CYANIDES
Chemical
Cyanide Compounds
Hydrogen Cyanide
TOTAL RELEASES AND
TRANSFERS
PERCENT OF TOTAL RELEASES
AND TRANSFERS"
Releases and Transfers (lbs/yr)a
Chemicals
SIC 28
4,120,654
1,967,177
6,087,831
77.59
Primary
Metals
SIC 33
717,896
475
718,371
9.16
Fabricated
Metals
SIC 34
415,031
0
415,031
5.29
Multiple
Code
SIC 20-39
281,953
49,937
331,890
4.23
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc., Inc.
U.S., EPA, Office of Pollution Prevention and Toxics, 33/50 Program Office
* Based on 1991 data
b Total for all 33/50 cyanides for all industry groups in 1991 was 7,846,044 Ibs.
Metal finishing includes electroplating and
other processes to increase the corrosion
resistance, hardness, aesthetic value or other
properties of a product. The 33/50 metals and
sodium cyanide are widely used in electroplating.
As discussed in Chapter 1, electroplating was
selected for substitutes evaluation because of the
potential benefits of identifying safe substitutes
that would reduce the use of chemicals in two of
the 33/50 chemical classes.
84
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CHAPTER 4; HYDROGEN CYANIDE AND CYANIDE COMPOUNDS
hydrogen cyanide on-site because of the hazards
posed by shipping and handling the poisonous
gas.
Air emissions contributed the largest fraction
of total releases and transfers reported by
cyanide compound production facilities. Process
air emissions from production processes can
originate from the continuous or intermittent
purging of inert gases from reactor vessels,
drying; beds, finishing columns, and other
process vessels. Fugitive air emissions result
when process fluid leaks from plant equipment
such as pumps, compressors and process valves.
Air emissions from storage and handling
operations also occur at production facilities.
Other sources of environmental releases or
transfers include the following:
• wastewater discharges directly from the plant
into rivers, streams, or other bodies of water,
or transfers to a POTW;
• on-site release to landfills, surface
impoundments, land treatment or another
mode of land disposal; and
• transfers of wastes to off-site facilities for
treatment, storage, or disposal.
Distribution of Environmental Releases by
Industry Group
Table 4.6 lists the total releases and transfers
and relative rank of hydrogen cyanide and
cyanide compounds in the 1991 TRI. Table 4.7
lists the top four industries that emitted the
largest quantities of 33/50 cyanide compounds
and their total reported releases and transfers.
In 1991, the chemicals and allied products
industry contributed more than any other industry
to releases and transfers of both hydrogen
cyanide and cyanide compounds, accounting for
almost 78 percent of the total. Further, releases
and transfers reported by facilities that produce
hydrogen cyanide accounted for nearly 21
percent of the total emissions of hydrogen
cyanide reported by the chemicals and allied
products industry. The primary metals industry
also contributed a significant fraction (more than
nine percent) of the total releases and transfers of
cyanide compounds.
USES OF THE 33/50 CYANIDE
COMPOUNDS
Hydrogen cyanide is used as a reagent to
manufacture methyl methacrylate, acrylonitrile,
adiponitrile, and sodium cyanide. A large
number of other uses, all relatively small in
consumption of hydrogen cyanide, include the
manufacture of ferrocyanides, acrylates, ethyl
lactate, lactic acid, chelating agents, laundry
bleaches, and Pharmaceuticals.
Sodium cyanide is used to extract gold and
silver from low grade ores in mining operations.
It is also used extensively in the electrodeposition
of gold, silver, copper, zinc, brass, and
cadmium. Also, sodium cyanide is used in the
manufacture of intermediates for later chemical
synthesis of Pharmaceuticals, dyes, vitamins, and
plastics.
The uses of hydrogen cyanide and sodium
cyanide are illustrated in a chemical-use tree
diagram shown in Figure 4.1,14 The numbers
along each branch of the chemical-use tree are
weight fractions of the usage of the chemical or
product in the first box to produce the chemical
or product in the second box. For example, in
Figure 4.1, ten percent of the hydrogen cyanide
produced is used to manufacture sodium cyanide;
90 percent of the sodium cyanide produced is
used to extract precious metals from their ores.
Some of the use clusters that incorporate the
33/50 cyanide compounds into their
formulations, or rely upon them in the
manufacturing process, also use other 33/50
chemicals in their manufacture. Methyl
methacrylate products fall into the use clusters of
plastics and resins, which includes materials that
are manufactured from the 33/50 aromatics.
Plastics and resins were selected for substitutes
evaluation as discussed in Chapter 2.
83
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PARTI; PRIORITY CHEMICALS
ENDNOTES
1 Hampshire Research Assoc., Inc., Toxics in the Community, US EPA, Office of Toxic
Substances, Economic and Technology Division, (Washington: GPO, September, 1991).
2 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed. (New York: John Wiley 1993)
Vol.7.
3 "Sodium Cyanide," Hazardous Substances Data Bank, November 9, 1990.
!
4 Ibid.
5 "Hydrogen Cyanide," Hazardous Substances Data Bank, April 27, 1992.
6 Ibid.
7 Ibid.
8 "Chemical Profile: Hydrogen Cyanide," Chemical Marketing Reporter, June 18, 1990.
9 "MMA Chemical Profile," Chemical Marketing Reporter, January 14, 1991.
10 "Sodium Cyanide Market Turns Around in a Hurry," Chemical Marketing Reporter, February 11,
11 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wilev 1993)
Vol.7.
12 Chemical Marketing Reporter, August 2, 1993.
13 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
Vol. 7.
14 Sources for Figure 4.1:
"Hydrogen Cyanide," Chemical Marketing Reporter, May 24, 1993.
"MMA Chemical Profile," Chemical Marketing Reporter, January 14, 1991.
"NaCN Oversupply Leads HCN to Other Outlets," Chemical Marketing Reporter, August 2, 1993.
86
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CHAPTER 4: HYDROGEN CYANIDE AND CYANIDE COMPOUNDS
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PARTH; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
formulation has specific characteristics and
various 33/50 metal applications. A brief
description of these is presented below.
Primary alkaline and zinc-carbon (also called
Leclanche) cells both use zinc as the anode,
manganese dioxide (MnO2) as the cathode, and
an electrolyte separating the two electrodes. The
alkaline cells utilize a powdered zinc anode and a
potassium hydroxide (KOH) solution as the
electrolyte; the zinc-carbon anode is solid zinc
and the electrolyte is an ammonium chloride-zinc
chloride matrix. The zinc-carbon cell was the
first so-called dry cell battery due to the
application of gelatin, agar, and flour in the
electrolyte matrix to make it spill proof. Until
recently, mercury was added to alkaline and
zinc-carbon batteries to inhibit hydrogen gas
evolution on the zinc electrode, thus preventing
the effects of hydrogen - increased internal
electrical resistance and corrosive reactions.1 A
build-up of gas can also break the safety vents
provided on batteries to prevent explosion from
excessive gas pressure. Once the safety vents
are broken, the corrosive electrolyte can leak out
and the cell will no longer function. Reduction
and elimination of this use of mercury by
industry has been significant.
The zinc-silver cell, commonly known as the
silver cell, is another battery system which
utilizes zinc as the anode. A silver oxide (Ag2O)
material is used as the counter electrode. This
system, most commonly a button cell design,
replaces zinc-mercuric oxide button cells in
specific constant-voltage uses due to its improved
operating conditions. Mercury is still added to
the anode of this battery to prevent hydrogen gas
evolution. Current applications of silver ceils
include watches and calculators.2
2^inc-air batteries utilize air as the cathode
oxygen source rather than a metal oxide
electrode (e.g., MnO2). The anode is zinc
powder typically mixed with an electrolyte
solution of KOH. This design for the zinc-air
battery presents advantages and disadvantages
over other battery systems. Because the oxygen
in the air functions as the cathode, the space
within the cell normally occupied by the metal
oxide can now be filled with more zinc, thus
increasing the battery's useful life. To allow the
flow of air into the cell, ventilation holes are
added to the battery's casing. These holes, while
allowing the free passage of air into the cell, also
allow any hydrogen gas generated at the zinc
anode to escape. Therefore, the need for
mercury at the anode is reduced, and has been
eliminated at least by one battery manufacturer
(Eveready). The main disadvantage is that once
the ventilation holes are unsealed for use, the
cells continually discharge because the flow of
air is continuous. Therefore, zinc-air batteries
are utilized in continuous use applications.3
Primary cells which use mercury compounds
as an electrode are commercially known as
"heavy duty" batteries. The electrode materials
are mercuric oxide with graphite (cathode) and
powdered zinc (anode).4 These cells typically
contain 40 percent by weight mercury, present
both as an electrode and gas inhibitor. Their
applications are usually associated with hospital
facilities where a constant voltage discharge is
required over the entire life cycle of the battery.
Advances in alkaline and other primary batteries,
however, have significantly impacted the need
and availability of the heavy duty cells.
Manufacturing of these batteries occurs outside
the U.S., and only a limited number of
companies choose to distribute them here.
Another primary cell configuration is the
lithium battery, which has a lithium anode.
Lithium batteries use a variety of cathode and
electrolyte materials, and are classified according
to the state of the cathode, either liquid or solid.
Liquid cathodes of sulfur dioxide (Li-SO2) and
thionyl chloride (Li-SOCl2) also serve assart of
the liquid electrolyte of the cell. Solid cathode
cells include carbon monofluoride (Li-CF),
manganese dioxide (Li-MnOj), iron disulfide (or
iron pyrite, Li-FeSj), and iodine (Li-I2) and
contain liquid electrolyte. The liquid electrolyte
of both liquid and solid cathode cells is one or a
combination of many lithium metal salts in an
organic solvent. The applications for lithium
batteries vary, and include heart pacers and other
low drain applications. Button cells of Li-FeS2
88
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CHAPTERS
BATTERIES
Batteries are an integral part of modern,
everydaiy life - from their use in portable
appliances to lead-acid automotive batteries. All
of the 33/50 metals except chromium (i.e.,
cadmium, lead, mercury, nickel) are used in
battery fabrication, with batteries representing
the single largest use of lead and cadmium. The
use of mercury has declined substantially in
recent years, however, due to product redesign
initiated by the battery manufacturing industry.
This chapter presents the uses of 33/50 metals
and metal compounds in batteries, substitutes for
the 33/50 metals, and the accomplishments of the
battery industry to reduce mercury use in
batteries.
Batteries represent the single largest uses of
lead and cadmium, and, until recently, were
among the largest uses of mercury. Today,
health and environmental concerns, combined
with legislative mandates, have spurred battery
manufacturers to redesign their products to
greatly reduce the use of mercury.
INDUSTRY PROFILE
A battery is a device that converts chemical
energy into electrical energy. Primary batteries
allow only one continuous or intermittent
discharge of electrical energy because the
chemical reaction that supplies their current
cannot be reversed. Secondary batteries can be
recharged by passing a direct current through the
cell in the opposite direction to the current flow
on discharge. Recharging the cell regenerates
the active chemicals within the cell by reversing
the chemical reaction that occurs during
discharge. Secondary batteries are also called
storage batteries. Primary batteries are available
in configurations of " AAA," " AA," " C," " D,"
9-volt, and button cells. Secondary battery
configurations include 12 volt lead-acid batteries
and AAA, AA, C, D, and 9-volt NiCd batteries.
Primary and secondary batteries are discussed
further in the sections below.
Primary Batteries
Primary batteries include alkaline, zinc-
carbon, zinc-air, silver, mercuric oxide (heavy
duty), and lithium cells. Each battery
87
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
TABLE 5.2 YEARLY MERCURY CONSUMPTION IN BATTERIES
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
Consumption
(short tons)
887.4
1128.6
1049.6
827.0
587.6
493.5
275.6
116.9
19.8
17.6
Percent of Total
47.5
54.3
55.4
47.3
36.9
29.8
20.6
14.7
3.2
2.6
- Percent Change
+ 27.2
-07.0
-21.2
-29.0
-16.0
-44.2
-57.6
-83.0
-11.1
Source:
U.S. Bureau of Mines, Dept. of the Interior, 1993
Price of Batteries
Primary batteries have much lower initial
cost than secondary batteries. In addition,
secondary batteries have the added cost of a
battery charger. Secondary batteries are the
more economical option, however, when the cost
is spread over the expected life of the battery.
Table 5.3 presents the price of primary alkaline
and secondary NiCd household batteries and
the price of lead-acid automotive batteries.
Cadmium, lead, nickel, and mercury are all
used as electrodes in battery designs. Mercury
is also used as an additive in cells with zinc
electrodes, although this use of mercury has
decreased substantially in recent years.
TABLE 5.3 PRICES OF BATTERIES
Battery Size
9V
D
C
AA
AAA
12V (automotive)
Price Range3 ($/battery)
Alkaline
0.50 to 2.36
0.50 to 2.36
0.50 to 2.36
0.50 to 2.54
0.62 to 2.39
N/A
NiCdb
5.00 to 6.96
3.35 to 3.48
3.35 to 3.48
2.24 to 2.75
2.35 to 2.74
N/A
Lead-Acid
N/A
N/A
N/A
N/A
N/A
29.97 to 89.95
' Price ranges are approximate, based on prices in Knoxville, Tennessee area
b Prices for NiCd battery rechargers range from about $8.47 to $29.95
N/A: Not Available
90
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CHAPTERS: BATTERIES
and Li-I2 have replaced significantly the uses of
silver cells and alkaline batteries, respectively, in
low drain, long life applications.5
Secondary Batteries
The largest segment of the U.S. battery
market is the lead-acid storage battery used for
automotive starting, lighting, and ignition (SLI).
SLI batteries supply current for operation of the
cranking motor and the ignition system when the
engine is being cranked for starting, and for
lights and electrical accessories when the
generator is not operating fast enough to handle
the electrical load. Besides their use as
automotive batteries, lead-acid batteries are used
as industrial standby and traction batteries.
Sealed lead-acid batteries are used in security
and alarm systems, for emergency lighting, and
in consumer products as a cordless, portable
power supply.
Secondary alkaline cells contribute 20 percent
of the worldwide secondary battery market, but
have traditionally been used in only highly
specialized, military applications.6 However,
advances in the technologies of rechargeable
alkaline cells have resulted in the recent
marketing of these cells in the consumer market.
NiCd batteries are the best known secondary
alkaline battery. NiCd cells use a cathode of
nickel oxide and an anode of cadmium. Sealed
NiCd batteries find extensive use in portable
appliances, calculators, and computers where
high rate power drains are experienced.
Sintered plate NiCd batteries are used in
extremely high discharge rate functions like
starting small jet and helicopter engines or
auxiliary power units in large military jets
and helicopters. Sintered NiCd batteries
are also used to provide emergency power
for critical electrical systems. New designs
have extended their applications in electric
vehicles where NiCd cells represent 20
percent of the secondary battery market.
Quantity of 33/50 Metals Used in Batteries
Table 5.1 presents the total weight of lead,
mercury, cadmium, and nickel consumed in
all applications in 1992 and the weight and
percentage of these metals consumed in battery
fabrication (calculated from chemical-use
trees). Battery consumption of cadmium
has increased from 36 percent in 1989 to 55
percent in 1992. U.S. Bureau of Mines data
indicate that the amount of mercury used in
household batteries decreased 92 percent
between 1984 and 1989. Table 5.2 traces this
dramatic change in mercury consumption in
batteries from 1983 to 1992. Conversely, the
amount of lead used in the typical lead-acid
automotive battery has increased in recent
years to 22 pounds. Manufacturers have
increased the lead content in response to demand
for better cold-cranking power and longer battery
life.
TABLE 5.1 QUANTITY OF 33/50 METALS CONSUMED IN BATTERIES
1992 Short Tons
33/50 Metal
Lead
Mercury
Cadmium
Nickel
Total Weight
Consumed
1,336,300
685
4,102
130,700
Total Weight in
Batteries
1,073,050
17.8
2,225.6
<650
% in Batteries
80.3
2.6
55
<0.50
89
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PART D: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
lead produced in the U.S. is used to manufacture
lead batteries, a significant portion of the
primary lead industry emissions can be attributed
to batteries. Using the same principle, portions
of the emissions from the production of nickel
and cadmium can also be attributed to the battery
manufacturing process.
Environmental Releases of 33/50 Metals from
Battery Manufacturing
The storage battery and primary battery
manufacturing industries are classified under SIC
codes 3691 and 3692, respectively, and are
required to report their environmental releases
and transfers in TRI. Table 5.4 presents the
1991 TRI data for SIC 3691. Table 5.5 lists the
1991 TRI data for SIC 3692. Releases and
transfers of 33/50 metals reported by these
industries in 1991 were more than 2.6 million
pounds. As with releases from the primary non-
ferrous metals industry, lead and lead
compounds were the primary pollutants,
contributing almost 37 percent of the total. Off-
site transfers were by far the largest categories of
environmental releases of the 33/50 metals from
battery manufacturers, followed by on-site
releases to air.
Environmental Releases of the 33/50 Metals
from Battery Recycling
Lead-acid batteries are the only batteries that
are currently recycled on a large scale.
Recycled lead supplied 65 percent of the lead
produced in the U.S. in 1988.9 This share of
lead production from recycled feed has been
increasing since 1983.10 Government studies
show lead-acid battery recycling rates peaking at
87.3 percent in 1980, declining to a low of 58.5
percent in 1985 and rebounding to 80 percent by
1987. Estimates placed the lead-acid battery
recycling rate at more than 90 percent for 1989
and 1990. With nearly 1.1 million short tons of
lead used in battery fabrication, a recycling rate
of 95 percent indicates more than 110 million
pounds of lead is unaccounted for each year,
perhaps being disposed of in landfills or being
stored by the consumer.
Reclaimed lead batteries are typically sent to
factories where the lead, sulfuric acid, and
plastics (polypropylene case and PVC separators)
are separated. The acid is reused as a
component of fertilizer or neutralized for
disposal. The polypropylene is chipped and sold
to reprocessors and the PVC is usually
discarded. The lead is smelted into ingots. Slag
from the smelting process contains three to five
percent lead that must be disposed of, usually as
hazardous waste.11
The secondary lead smelting industry is
classified under SIC 3341. Table 5.6 presents
the 1991 TRI data for lead and lead compound
releases from SIC 3341. Nearly 96 percent of
the lead released from lead smelters was sent to
land-based disposal facilities off-site.
Environmental releases of the 33/50 metals
occur from metal mining and refining, battery
manufacturing and recycling, and the disposal
of spent batteries as municipal solid waste.
Rechargeable NiCd batteries have accounted for
more than half of the cadmium discards in
municipal solid waste since 1986.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
The 33/50 metals and metal compounds are
toxic chemicals that cause both acute and chronic
health effects. Long-term exposure to the 33/50
metals may cause organ damage, or, in some
cases, cancer. Chapter 1 discussed the health
effects from exposure to metals in more detail.
Potential environmental effects due to the
disposal of batteries are summarized below.
Municipal solid waste is disposed of by
incineration or in landfills. Problems from the
disposal of batteries are present when the
discarded batteries are burned. The air pollution
caused by incineration has the potential to emit
mercury vapor, and the incinerator ash that is
usually disposed of in a landfill often contains
92
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CHAPTERS: BATTERIES
DESIRED PROPERTIES OF BATTERIES
The efficacy of batteries is evaluated using a
number of parameters. Some of the more
important ones are the cycle life, energy density,
nominal voltage, self-discharge rate, and specific
energy of the battery. Cycle life is the number
of discharge-charge cycles that a rechargeable
battery will achieve before failure. Energy
density is used to express the stored energy as a
function of battery volume. Nominal voltage is
the expected voltage of a fully-charged battery at
a specified discharge rate and temperature. Self-
discharge rate is the percentage capacity loss per
unit time for a battery during periods of nonuse.
Specific energy is the stored energy as a function
of the weight of the battery.7
Consumers prefer an economical household
battery that can be used in many applications, has
a good shelf life, and is economical.
Traditionally, primary batteries have met these
needs, but rechargeable household batteries are
gaining a larger market share as rechargeable
battery technologies improve. In 1988, the
rechargeable battery market was growing at 15
percent per year, more than double the annual
growth rate that primary batteries were
experiencing. In 1993 the overall rechargeable
market was still at a 10 to 15 percent annual
growth rate. Some sources predict an annual
growth rate of near 30 percent by 1997 when
improved battery technologies become
commercialized.8
The growth in the rechargeable market is
attributed to the improved capacity of a typical
rechargeable cell and decreased internal
resistance of the cell that allows more power to
be delivered faster. Rechargeable batteries have
also benefitted from an increase in the efficiency
of electric motors that adds to battery efficiency.
Improvements and diversity of available battery
rechargers, as well as consumer concerns about
the disposal of spent primary batteries, have
contributed to a gain in market share for
rechargeable batteries.
Automotive batteries must meet additional
criteria, because of the short heavy loads they
must supply, and the temperature extremes to
which they are subjected. Therefore, automotive
batteries are designed to provide a high electrical
output and to have the ability to withstand
sub-zero or elevated temperatures.
Environmental releases of the 33/50 metals
and metal compounds from battery fabrication
occur from metal mining and refining through
recycling or disposal of spent batteries. The
following sections present the environmental
releases from the production of 33/50 metals, the
battery manufacturing process, and the recycling
of spent batteries.
Environmental Releases from Production of
the 33/50 Metals and Metal Compounds
Releases and transfers of the 33/50 metals and
metal compounds from the primary non-ferrous
metals industry were discussed in Chapter 1.
Total reported environmental releases of
cadmium, lead, nickel, mercury, and their
compounds in 1991 were almost nine million
pounds. Lead and lead compounds contributed
more than 8.2 million pounds (92 percent) of
these releases. Nickel and nickel compounds
accounted for the next largest fraction (six
percent) of the releases and transfers from the
primary nonferrous metals industry, but only a
small fraction of the nickel produced in the U.S.
(less than one percent) is used to manufacture
batteries. Cadmium and cadmium compound
releases totalled almost 145 thousand pounds, but
it is more difficult to apportion cadmium releases
by end-use since cadmium is produced as a by-
product of zinc refining. No releases of mercury
were reported by the primary non-ferrous
industry.
Using the principles of life cycle assessment
and the life cycle concept, some fraction of these
releases of metals and metal compounds from the
primary nonferrous metals industry can be
attributed to their end-use in batteries. For
example, since approximately 80 percent of the
91
-------
PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
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CHAPTERS: BATTERIES
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
elevated concentrations of metals. For example,
Warren County, New Jersey started a battery-
collection pilot program in 1989 after receiving
an EPA warning for high cadmium in its
municipal waste incinerator ash and mercury in
the stack. This rural county of only about
94,000 people collects about 1,300 pounds of
batteries each month. That translates into almost
16 thousand pounds of batteries being discarded
each year by one small, rural community.
Extrapolating the battery-discard rate across the
entire U.S. population gives an idea of the
enormity of the battery disposal problem.
Warren County sorts the batteries according to
those to be recycled and those to be landfilled.
Concentrations of leachable cadmium in the ash
have not exceeded EPA toxicity testing since the
battery-recycling program was initiated.12
Problems also exist when batteries are
improperly disposed of in a landfill. Disposal of
lead-acid batteries in a landfill is prohibited
because the sulfuric acid can leach and
contaminate groundwater. Corrosion products
encased in the battery are also susceptible to
leaching. Even with a recycle rate of 95
percent, lead-acid batteries have the potential to
be disposed of as municipal solid waste, although
some consumers may store these batteries in
their garage.13
Rechargeable NiCd batteries have accounted
for more than half of the cadmium discards in
municipal solid waste since 1980. Cadmium
discards in household batteries were 930 short
tons in 1986 and are expected to increase unless
NiCd batteries are replaced in some applications
by a safer substitute, or efficient programs
encouraging their collection are further
implemented (as in the example above).14
EVALUATION OF SUBSTITUTES
The health, safety, and environmental issues
associated with the use of the toxic 33/50 metals
in batteries has spurred the development of a
number of safer substitutes. Mercury has been
almost eliminated from carbon-zinc and alkaline
MnO2 batteries, at a much faster rate than
manufacturers believed was possible just a few
years ago, and at a rate that exceeds legislative
mandates. Research and development on
alternatives to NiCd batteries has exploded in
recent years, particularly in the area of nickel-
metal hydride (NiMH) and lithium rechargeable
batteries. NiMH batteries are currently being
used in some applications, but until recently this
technology was believed to be much farther from
volume production.
By substituting new materials for mercury at
the zinc anode, carbon-zinc and alkaline MnO2
battery manufacturers have reduced or
eliminated mercury from their products. In
addition, alternatives to NiCd batteries are now
available to the consumer as battery
manufacturers strive to produce safer products.
Progress is not as rapid in identifying
substitutes for lead-acid batteries that constitute
the vast majority of the battery wastestream.
Safer substitutes for lead-acid batteries are being
developed, however, and these technologies
could see rapid advancement as societal
pressures to reduce the use of toxic chemicals
increase.
The following sections discuss the elimination
or reduction of mercury in carbon-zinc and
alkaline MnO2 batteries; substitutes for NiCd
rechargeable batteries; and the status of research
and development on substitutes for the lead-acid
battery.
Safe Substitutes for Mercury in Carbon-Zinc
and Alkaline MnO2 Batteries
In response to legislation in several states,
carbon-zinc and alkaline MnO2 battery
manufacturers have reduced or eliminated
mercury from their products through material
use modifications. These reductions in mercury
use exceeded even legislative demands, and the
industry is now initiating efforts to eliminate
mercury entirely. Table 5.7 presents state
legislation dates for low mercury and no mercury
formulations for alkaline and zinc-carbon
96
-------
CHAPTERS: BATTERIES
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PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Zinc-carbon cells, prior to mercury reduction
initiatives, contained mercury in a concentration
of 100 to 150 ppm (0.01 to 0.015 percent by
weight). The earliest state legislative
requirement for implementation of "no mercury
added" was January, 1992 (New Jersey). All
manufacturers met this requirement for all zinc-
carbon battery sizes by April, 1992. Surface
active organic compounds which coat the zinc
electrode, and potassium chromate or dichromate
which forms an oxide film on the zinc, are some
material substitutes to the mercury additives.15
Mercury free separators for both zinc-carbon
and alkaline MnO2 batteries are among the
technologies allowing mercury-free battery
alternatives. These technologies are proprietary
to battery companies and their compositions can
be found mainly in patent literature. For
example: the separator for zinc-carbon batteries
has kraft paper coated by a polymer or polymer
fiber layer. The layer can be poly amide,
polyvinyl alcohol, polyvinyl acetate,
polyethyleneimine, urea-formaldehyde polymers,
or amine-formaldehyde polymers.16 The
separator for the alkaline MnO2 battery made of
woven or nonwoven polymeric fibers is coated
on one or both sides with a gel, (e.g.,
carboxymethylcellulose, CMC), modified starch,
polyvinyl alcohol, or hydroxypropyl cellulose.
The zinc anode has no mercury or cadmium and
contains 0.005 to 1 percent iodine and 1 to 1000
ppm of stabilizer, e.g., an ethoxylated
fluoroalcohol or mercaptan and polyethoxylated
alcohol.1' Another example is alkaline MnO2
batteries containing HO-terminated
perfluoroalkylpolyoxyethylenes corrosion
inhibitors. The inhibitors are
CF3(CF2)mS02NR(CH2CHR'0)nH, where m=l-
20, n= 3-30, R=CMO alkyl, and R1 =H or Me,
and have molecular weight of 500 to 2500. The
zinc alloy contains iodine, <0.1 percent
mercury, and optionally lead, aluminum,
bismuth and/or calcium.18
Safe Substitutes for Mercury in Button Cell
Batteries
Most button cell designs that include mercury
as an additive to suppress hydrogen gas
evolution, including alkaline, zinc-carbon, silver
oxide, and zinc-air, have not been included in
state legislative requirements. Typical mercury
contents of these batteries range from 1 to 24
milligrams per cell. Even without legislative
requirements, battery manufacturers are
attempting to eliminate the added mercury from
these cells as well. For example, Eveready has
recently marketed a zinc-air cell that has zero
mercury added.
Zinc-mercuric oxide button cells which use
mercury as an electrode material have been the
subject of legislation, however. Since 1992,
bans on the sale of zinc-mercuric oxide button
cells and requirements for the collection (the
responsibility of the manufacturer or point-of-
sales) of these cells have existed in many states.
Table 5.8 presents the state regulations for the
mercuric oxide button cells.
Safe Substitutes for Mercuric Oxide Heavy
Duty Batteries
In the case of mercuric oxide heavy duty
batteries, mercury is present as an electrode
material. The mercury content of these batteries
is typically 35 to 40 percent by weight. With
improvements in other battery designs (both
alkaline and zinc) that meet the operating
characteristics and performance requirement of
the mercuric oxide battery, manufacturers expect
the complete phase-out of these batteries from
civilian applications. Military applications,
representing a large sector of this market, may,
however, continue to use these cells.
Safe Substitutes for Nickel-Cadmium
Batteries
Like the mercuric oxide in heavy duty
primary batteries, the cadmium or nickel in
NiCd batteries cannot be reduced since they are
the active components of the battery. Thus,
alternative electrode materials that are
environmentally non-hazardous should be
considered. Nickel-metal hydride rechargeable
batteries use a new battery chemistry that has a
metal hydride electrode as a replacement for
some applications of NiCd batteries.
Rechargeable lithium batteries, another
98
-------
CHAPTERS: BATTERIES
batteries. Most legislative requirements and
manufacturer accomplishments apply to batteries
of all sizes.
Prior to legislation and manufacturer
initiatives, typical alkaline batteries contained 0.8
to 1.2 percent mercury (by weight) as an additive
to suppress gassing at the zinc electrode.
Mercury was used to combine with the zinc
anodic material and form a zinc/mercury
amalgon. This reduced the rate at which the zinc
oxidized with the alkaline electrolyte, thus
reducing the generation of hydrogen gas. By
substituting new materials for mercury at the
zinc anode, each U.S. alkaline battery
manufacturer was able to meet the "250 ppm"
and "no mercury added" requirements of state
legislation. By May of 1991, all manufacturers
met the "250 ppm" requirement, one year ahead
of legislative requirements. By the end of 1993,
all alkaline battery manufacturers had met the
"no mercury added" requirements, three years
ahead of any state legislative requirements.
TABLE 5.7 STATE LEGISLATIVE DATES FOR LOW MERCURY/NO MERCURY
FORMULATIONS FOR ALKALINE AND ZINC-CARBON BATTERIES
State
Federal (proposed)
Arkansas
California
Connecticut
Florida
Iowa
Maine
Minnesota
New Hampshire
New Jersey
New York
Oregon
Rhode Island
Vermont
Wisconsin
Alkaline
250 ppm (0.025%)
Mercury
—
—
1-1-94 (mfg. date)
1-1-92 (mfg. date)
7-1-93 (sale date)
7-1-93 (sale date)
1-1-94 (sale date)
2-1-92 (mfg. date)
1-1-93 (mfg. date)
1-1-92 (mfg. date)
1-1-92 (mfg. date)
1-1-92 (mfg. date)
1-1-92 (mfg. date)
2-1-92 (mfg. date)
No-Mercury Formula
1-1-96 (mfg. date)
1-1-96 (mfg. date)
1-1-96 (mfg. date)
—
1-1-96 (sale date)
1-1-96 (sale date)
1-1-96 (sale date)
1-1-96 (sale date)
1-1-96 (sale date)
1-1-96 (mfg. date)
—
—
—
1-1-96 (sale date)
1-1-96 (mfe. date)
Zinc-Carbon
No-Mercury Formula
1-1-95 (mfg. date)
1-1-94 (mfg. date)
1-1-94 (mfg. date)
1-1-93 (mfg. date)
1-1-96 (sale date)
—
1-1-93 (sale date)
—
1-1-93 (mfg. date)
1-1-92 (mfg. date)
1-1-93 (mfg. date)
—
—
7-1-94 (mfe. date)
Source:
National Electrical Manufacturers Association, 1993
97
-------
PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
cobalt, aluminum, and manganese (Mm, Ni, Co,
Al, Mn), the electrode achieves a service life
about 100 times greater than that of LaNi5.
Sanyo is developing an optimum component ratio
for these types of alloys. The AR, type of alloys
are also known as the Ovonic metal hydrides
alloys. These alloys are based on vanadium,
nickel, zinc, and titanium, and they are
proprietary to and patented by The Ovonic
Battery Company (USA). Some of the
advantages of the Ovonic batteries include higher
energy density, the absence of memory effect,
and the reduction of environmentally and
ecologically toxic and hazardous elements.
Ovonic batteries compare favorably with NiCd
batteries on a dollar per Amperehour basis.
Ovonic battery technology has been licensed to a
number of companies such as Varta AG
(Germany), the largest European battery
manufacturer, Hitachi Maxell (Japan), and
Goldpeak Industries (Hong Kong).
Recently, Varta AG, Toshiba Battery
Company (Japan), and Duracell International
Incorporated (USA) have signed an agreement to
develop, standardize, and market NiMH
batteries. Goldpeak has been marketing some
types of NiMH batteries since 1990. Gates
Energy Products began marketing a "C" size
2300 mAh nickel-metal hydride cell in 1991.
The Portable Battery Division of Gates Energy
Products, Gainesville, Florida, is responsible for
marketing the nickel-metal hydride batteries.
Sanyo is marketing an electric shaver powered
by nickel-metal hydride batteries. The Sanyo-
developed nickel-metal hydride battery has an
energy density approximately 1.8 times that of
the conventional NiCd cell, while it can be
charged/discharged up to 500 times.
Lithium Batteries. Rechargeable lithium
batteries are also being developed as possible
substitutes for NiCd batteries. The rechargeable
lithium cells have the advantages of high energy
density, high cell voltage, and good capacity
retention. The weak points of the rechargeable
lithium cells are a limited cycle life (typically
100 to 200 cycles), difficulty in applying a fast
charge to the cells, and safety concerns due to
the lithium metal flammability. During cycling,
lithium deposition on charge is more or less
dendritic, mossy, and porous. This causes losses
of lithium by reaction with the electrolyte, or
separation of particles from the electrode
substrate, resulting in short circuiting through the
separator. The solutions to these problems,
besides a suitable stable electrolyte, are the use
of the following: 1) a large excess of lithium; 2)
a large surface area to decrease the current
density; and 3) a microporous separator to
prevent dendrites. This separator is one of the
key-points for lithium cell development.
Positive new developments in lithium
rechargeable cell technology include a lithium-
ion technology and a lithium polymer cell. The
lithium-ion system eliminates the use of metallic
lithium as the anode, and uses carbon and metal
oxides, the electrolyte and cathode materials, to
initiate the chemical reaction. Lithium is present
within the carbon's molecular structure which
represents the micro-porous separator. Sony
Energytec announced its lithium-ion cells
generate four times as much energy as nickel-
cadmium batteries. Lithium polymer systems
use a polymeric electrolyte in a solid state cell to
eliminate the weak points of the traditional
rechargeable lithium cells. The presence of the
polymer, representing the microporous
separator, prevents the recharging reaction from
speeding out of control. Prototypes of these
batteries are claimed to last four times as long as
nickel-cadmium batteries.19
Reusable Alkaline Batteries. In September,
1993, Rayovac began marketing the first
reusable alkaline battery called Renewal. This
new battery design functions like traditional
alkaline batteries, but can be recharged at least
25 times. The design and chemical formulation,
which is patent-protected, varies from
traditional, non-rechargeable alkaline batteries,
and is cadmium free and 99.975 percent mercury
free (< 250 ppm mercury). The life-time of
each charge of the Renewal battery is as long as
traditional alkaline batteries, and up to three
times longer than current NiCd technologies.
And, unlike NiCd rechargeable batteries,
reusable alkaline batteries can retain a charge for
up to five years. The recharging units,
100
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CHAPTERS: BATTERIES
TABLE 5.8 STATE REGULATIONS FOR MERCURIC OXIDE BUTTON CELLS
Jurisdiction
Federal
Arkansas
California
Connecticut
Florida
Iowa
Maine
Maryland
Michigan
Minnesota
New Jersey
Hearing Aid
Dispensers
All others
Rhode Island
Vermont
Status of Legislation
Not yet introduced
Passed
Passed
Passed
Passed
Passed
Passed
Passed
passed
Passed
Passed
Passed
Passed
Effective Date
Ban
1-1-95
1-1-94
1-1-94
10-1-93
1-1-93
2-1-92
1-1-94
1-20-92
1-1-93
1-1-93
Collection
—
—
1-1-92
7-1-96
7-1-94
1-1-98
Until
1-1-94
—
—
—
Note(s)
—
—
b,c
a.b
a
d
a
Source:
National Electrical Manufacturers Association, 1993
* Battery manufacturers financially responsible for collection, transportation, disposal, consumer education, etc.
Failure to meet these requirements results in a sales ban for the manufacturers's mercury button cells.
b Battery manufacturers not expressly responsible, but retailer required to collect.
c Battery manufacturers not expressly responsible, but state regulatory agency to issue regulations.
d $2/battery required at time of sale, unless trade-ins of used batteries made at that time.
alternative to NiCd batteries, offer a complete
change in electrode materials. Both battery
alternatives, discussed further below, are now
commercially available.
Nickel-Metal Hydride Batteries. Two
general classes of metallic alloys have been
utilized as the basis for the nickel-metal hydride
negative electrode. These are rare earth/nickel
alloys generally based around lanthanum nickel
alloys (LaNi5 - the so called AB5 class of alloys)
and alloys consisting primarily of titanium and
zirconium (designated as ABj alloys). By
substituting cobalt for some nickel in LaNi5 and
misch metal (Mm), which is a mixture of some
rare earth elements, it is possible to increase the
life span of the batteries significantly. By
eliminating the nickel portion in favor of a
multicomponent alloy of misch metal, nickel,
99
-------
PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Reusable
Alkalines
Rechargeable
Lithium
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102
-------
CHAPTERS: BATTERIES
"Renewal Power Stations," can recharge four
AA or AAA batteries (portable station - $15.00)
or any configuration of eight batteries (table top
station model - $30.00). The time required to
recharge these batteries ranges from three to five
hours (sizes A A and AAA) to overnight (sizes C
and D). Rayovac recharging units for the
Renewal are specifically designed for these
batteries, including a computer chip which senses
when a battery is fully charged. SLM, a battery
marketer, has recently marketed a recharger that
can recharge either alkaline or NiCd batteries.
Renewal battery prices range between $5.00 and
$6.00 for C and D two-packs or AA and AAA
four-packs.20
Comparison of Secondary Batteries. Table
5.9 is a comparison of sealed lead, NiCd,
current NiMH, rechargeable lithium battery, and
reusable alkaline battery chemistries for typical
battery sizes. Rechargeable lithium or NiMH
batteries are expected to meet or exceed the
performance of sealed lead and NiCd batteries in
the areas of energy density, specific density, and
nominal voltage. Increased energy density
means longer run times between charges which
can make these batteries preferable in certain
applications. Low rate power drain applications,
such as computers, camrecorders, cellular
phones, and pagers can utilize these new battery
systems. NiMH batteries, however, cannot
deliver the necessary current to operate high rate
power drain products like power tools. Another
problem with these batteries lies in their high
costs. The battery industry reports that NiMH
batteries cost about twice as much as NiCd
batteries, which would have significant impact on
the marketability of lower-cost rechargeable
products.21 Furthermore, these battery
substitutes still contain elements of concern,
although the 33/50 metals have been
reduced/eliminated. For example, arsenic which
is a potential ingredient of some rechargeable
lithium battery chemistries is an acute poison.
The recyclability of the rare earth metals used in
the metal alloys of NiMH batteries has been
questioned.
Safe Substitutes for Lead-Acid Batteries
Possible safe substitutes for lead-acid
automotive batteries are primarily in the research
and development stage. In the near term, NiCd
batteries or nickel-zinc (NiZn) batteries could be
employed to replace lead-acid batteries. Future
lead-acid battery substitutes may include the
nickel-iron (NiFe) battery or the sodium-sulfur
(NaS) battery. As safe substitutes for products
made from or containing the 33/50 chemicals in
their formulation, NiCd batteries are not
acceptable alternatives for lead-acid batteries and
are not discussed here. Substitutes that contain
nickel also do not eliminate the use of the 33/50
metals, but have been the subject of substantial
research and development.
NiZn batteries could be substituted for lead-
acid batteries in the near-term, but they do not
have equivalent performance qualities. NiZn
batteries have a lower specific energy and a
limited cycle life (50 to 200 discharge-charge
cycles, compared to about 750 for lead-acid).
NiZn batteries also cost two to three times more
than an equivalent lead-acid battery.22
Research and development of the NiFe
battery is at the pilot plant stage. The NiFe
battery has mainly been evaluated as a possible
advanced battery for use in electric vehicles. In
that application, the NiFe battery provides 1.5 to
2 times the vehicle range of the lead-acid battery.
A primary disadvantage of the NiFe battery is
that the battery system must include a system for
regular watering and the removal of hydrogen
gas generated during recharging.23 In addition,
cost is higher for the NiFe battery.
NaS batteries are still under development.
These batteries use a ceramic beta-alumina
electrolyte tube with a sodium anode and a
molten sulfur cathode on opposite sides within a
sealed, insulated container. NaS batteries have
potential safety problems due to the reactivity of
sodium and their high operating temperatures
(350 to 380°C). NaS batteries are expected to be
economical because they are made from
expensive materials and have a long projected
service life.24
101
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PART U: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENDNOTES
1 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wilev 1993)
Vol.3. " '*
Ullmann 's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag 1985)
Vol. A3.
3
Vol. 3.
2 Ibid.
Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
4 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag 1985)
Vol. A3. ''
5
Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1993),
Vol. 3.
6 Ibid.
7 "Solid State Batteries," NATO ASI Series E - Advanced Sciences, (Martinus Nighoff Publishers
1985).
8 Lawrence D. Maloney, ed., "Recovery Power With Rechargeables," Design News November
1988.
Correspondence with Norm England, The Portable Rechargeable Battery Association, April 22,
1994.
"The High-Voltage Rivalry in Batteries," Business Week, February 15, 1993.
9
Steve Apothekar, "Batteries Power Secondary Lead Smelter Growth," Resources Recvctinz
February 1990. 5'
10 Nicholas Basta, "Recycling Everything: Part 2 - Metals Recyclers Warily Eye New Sources,"
Chemical Engineering, Vol. 97, Iss. 12, December 1990.
11 Steve Apothekar, "Batteries Power Secondary Lead Smelter Growth," Resources Recycling
February 1990.
12 Ron Gasbarro, "Getting Rid of Batteries," Garbage, September/October 1991.
13 Douglas C. Wilson, "Sources and Fate of Heavy Metals in MSW Landfills: Lead, Zinc,
Cadmium, and Mercury," The Garbage Project, Bureau of Applied Research in Anthropology University
of Arizona.
14 Characterization of Products Containing Lead and Cadmium in Municipal Solid Waste in the
United States 1970 to 2000, US EPA, Pub. No. EPA/530-SW-89-015C, (Prairie Village, KS, June 1989).
15 "Getting a Charge Out of the Wastestream - Final Report," Recoverable Resources/Boro Bronx
2000, Inc., April 17, 1992.
104
-------
CHAPTERS: BATTERIES
Conclusions
Substantial progress has been made in the
design and manufacture of batteries that do not
contain 33/50 metals. Most of the successful
research, however, has been limited to
developing safe substitutes for the mercury and
cadmium used in batteries. The development of
low-mercury and mercury-free batteries should
eliminate batteries as one of the largest sources
of mercury in the nation's household hazardous
wastestream. Nickel-metal hydride and lithium
batteries have been introduced as alternatives to
the batteries employing a cadmium electrode. It
appears, however, that little or no efforts are
underway to identify substitutes for the nickel
electrode, except with rechargeable lithium
batteries. The rechargeable lithium battery will
not be without potential health and environmental
effects, however, if these batteries contain
arsenic.
Although lead-acid batteries contribute a
significantly greater amount of environmental
releases and transfers from their manufacture,
use and disposal, research on safe substitutes
for lead-acid batteries has not been as successful.
Nonetheless, several substitutes for lead-acid
batteries are currently being evaluated that may
be viable alternatives. Industry responded
rapidly when it became apparent that restrictions
would be placed on the amount of mercury
allowed in batteries. Concerns about the health
and environmental effects of cadmium were
probably also instrumental in hastening the
development of the NiMH battery. Similar
concerns about lead-acid batteries may hasten
the development of suitable substitutes.
103
-------
-------
CHAPTERS: BATTERIES
16 C. Daniel (CIPEL, S.A., Pile Wonder, S.A.), FR Demand Fr 2,627,632,25, August 1989,
Appel. 88/2, 236, February 24, 1988.
17 J.F. Audebert, J.C. Mas, A. Mendiboure (CIPEL, Wonder) Eur. Pat. Appl. EP 352,604,31,
January 1990, Fr. Appl. 33/10, 000017, July 25, 1988.
18 S. Suetsuga, A. Ota, K. Takada, Y. Nitta, Y. Nitsuta, K. Yoshizawa (Matsushita Electric
Company, Ltd., Japan, Kokai, Toyko, Koho, JP 02, 281, 561, November 19, 1990, Appl. 89/103, 823,
April 24, 1989, 7pp.)
19 Robert Neff, "The High-Voltage Rivalry in Batteries," Business Week, No. 3305, February 15,
1994, p. 116-117.
Reinhardt Krause, "High Energy Batteries," Popular Science, Vol. 242, No. 2, February 1993, p.
64.
20
Sare Hebel, "Rayovac Taps Into Reusable Batteries," Advertising Age, July 26, 1993, p. 10.
"Rayovac Unveils Rechargeable Alkaline," Dealerscope Merchandising, August 1993, p. 8.
21 Portable Rechargeable Battery Association, Comments on the Interim Draft Report, University
of Tennessee, "The Product Side of Hazardous Waste Reduction: Evaluating the Potential for Safe
Substitutes," January 28, 1994.
22 Preliminary Use and Substitutes Analysis for Lead and Cadmium in Products in Municipal Solid
Waste, US EPA, Office of Solid Waste, January 27, 1992.
23 Taylor Moore, "The Push for Advanced Batteries," EPRIJournal, April/May 1991.
24 Ibid.
105
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PART Eh PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
parts. For example, the textile industry uses
electroplating to increase the corrosion resistance
of metal textile manufacturing equipment. The
automotive industry plates parts like pistons,
cylinders, pump rods, and gear shafts to increase
their wear resistance. The heavy duty machinery
and tools industry uses electroplating to salvage
and repair equipment.1 Manufacturers of
household products use electroplating to improve
the physical properties of the product or simply
for decorative purposes.
Quantity of 33/50 Metals and Cyanides Used
in Electroplating
Electroplating is the second largest end-use of
nickel and nickel compounds, the third largest
end-use of cadmium and cadmium compounds,
and accounts for a substantial fraction of the
annual U.S. consumption of chromium and
chromium compounds. Although current data
are not available, in 1989 about ten percent of
the sodium cyanide produced was also used in
metal finishing applications.
The quantities of cadmium, nickel, and
chromium consumed in electroplating in 1992
were estimated using the chemical-use tree
diagrams and the reported total annual
consumption of these metals. Almost 574 short
tons of cadmium was consumed in electroplating
applications in 1992, representing a decline from
approximately 2,000 short tons (51 percent of the
consumption) in 1979.2 The decline in the
percent-use of cadmium for electroplating can be
partly attributed to the increased demand of
cadmium for nickel-cadmium batteries, but
cadmium's use as a metal coating has also
declined in recent years.
Nickel is the most widely used plating metal
and has the largest annual consumption of the
33/50 metals in this application. In 1987, the
U.S. consumed 22,650 short tons of nickel for
electroplating purposes. Of this, 89.6 percent
was sold as commercially pure nickel, and the
remaining 10.4 percent was in the form of nickel
salts. U.S. consumption of nickel for
electroplating was 14,377 short tons in 1992.
Sodium bichromate or chromic acid are the
chromium compounds commonly used to supply
chromium metal ions to a plating bath. Roughly
7,405 short tons of chromium compounds were
used in electroplating in 1992.
Price of 33/50 Metals and Cyanides Used in
Electroplating
Electroplating baths consist of metal ions in
acid, alkaline, or neutral solutions. The metal
ions are usually supplied to the bath either in
elemental form, as inorganic metal salts, or as
other metal compounds. Table 6.1 lists the 1994
price of some of the common chemical
compounds used in electrolytic solutions. The
metal salts or metal compounds used to supply
the metal electrolyte are typically the more
expensive components of the electrolytic
solution. Chemicals like sulfuric acid and the
cyanide compounds are used to dissolve the
metal or improve the properties of the plating
bath.
DESIRED PROPERTIES OF 33/50 METALS
AND CYANIDES IN ELECTROPLATING
There are a diversity of metals, metal
compounds, and electrolytic solutions used in
electroplating. The 33/50 metals are commonly
used because of their excellent corrosion
resistance, wear resistance, and decorative
properties. Sodium cyanide and potassium
cyanide, the cyanide compounds normally used
in electroplating, are widely used because they
impart desirable properties to the plating bath
and can improve the properties of the metal
plate.
The 33/50 metals are commonly used in
electroplating because of their excellent
corrosion resistance^ wear resistance^ and
decorative properties. Cyanide compounds are
used in plating baths to improve the properties
of the metal plate.
The desired properties of the 33/50 metals
and cyanides used in electroplating applications
are summarized below.
108
-------
CHAPTER 6
ELECTROPLATING
Electroplating is a process for depositing a
metal onto a substrate using an electrical current.
The metal plate provides corrosion or wear
resistance, and/or improves the appearance value
of an item. Three of the 33/50 metals, including
cadmium, chromium, nickel, and their
compounds, and the 33/50 cyanide compounds
are widely used in electroplating. Halogenated
solvents are also frequently used as a cleaning
step prior to electroplating (see Chapters 3 and
9). The use of the 33/50 metals and cyanides in
electroplating and the associated cleaning
processes results in the release and transfer of
substantial quantities of toxic chemicals to the
environment and contributes to the nation's
hazardous waste burden.
INDUSTRY DESCRIPTION
The plating of metal onto a substrate has been
practiced in industry for over a century and a
half. The first metal to be used in plating was
copper; hundreds of other metals and alloys are
currently used including brass, cadmium,
chromium, gold, iron, nickel, silver, and zinc.
Today, electroplating is the most common
method for depositing a metal coating on a
substrate.
The electroplating industry consists of two
sectors: 1) job shops or contract shops that
electroplate a metal coating on metals or other
materials (usually plastics) owned by a second
party; and 2) manufacturers who electroplate
their own products in captive shops under their
own management. Job shops are classified under
SIC 3471, the plating and polishing industry.
Manufacturers that perform captive
electroplating are usually classified under other
SIC codes, depending on their final products.
Not only does the electroplating process
result in the use and environmental release of
large quantities of the 33/50 metals and
cyanides, it can also result in the use and
release of the 33/50 halogenated solvents. The
solvents are frequently used to clean oils and
grease from a substrate prior to electroplating.
Electroplating applications range from the
high-technology manufacture of printed circuit
boards to the production of decorative metal
107
-------
PARTO; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
characteristics of a substrate. Nickel coatings
are resistant to caustic alkalis, as well as to most
alkaline and neutral salt solutions.
Cyanide Compounds
Cyanide plating baths have the advantage of
accommodating a wide range of electrical
current. They are also excellent for removing
tarnish or undesirable films from objects to be
plated. Coatings of cadmium, iron, gold, and
zinc often use these compounds. The cyanides
cause an even metal deposit to form that has
lower sensitivity to impurities present in the
electrolytic solution. Thus, metal plates can be
produced with increased corrosion resistance.
Generally, potassium cyanide is preferred for the
plating of precious metals like gold and silver.
Sodium cyanide is used more often for the less
expensive metals because of its lower cost.9
ELECTROPLATING PROCESS
DESCRIPTION
The electroplating process consists of a
number of steps, including cleaning,
electroplating, rinsing, and drying.
Electroplating is usually done in a plating bath
but brush plating is also done. The following
describes the electroplating process and the
characteristics of plating baths that use the 33/50
metals.
Plating Bath Process
A rack or barrel is typically used to hold the
parts during the electroplating process. Rack
plating is most commonly used, but barrels are
used for smaller parts that can tumble freely
without surface impingement. Barrel plating can
also be more cost-effective for smaller parts
because it allows for bulk handling.
After the parts are loaded onto a rack or into
a barrel, cleaning is required to remove oil,
grease, soil, and oxide films from the substrate
and ensure good electroplate adhesion. The
cleaning operation usually consists of one or
more sequential treatments in a solvent degreaser
(see Chapter 9), an alkaline solution, and an acid
solution. The rack or barrel is then positioned
into the electroplating baths and direct current
loads are distributed to the substrate. The
charged substrates act as cathodes that reduce the
metal ions from solution onto the substrate's
surfaces. The metal ions in solution are
replenished by the dissolution of metals from
anodes in bar form or in small pieces contained
within the bath, or with the addition of metal
salts. Electroplated coating thicknesses usually
range from 0.00025 to 0.0015 inch, and are
usually dependent upon the time the part is left in
the bath. Thicker coatings are sometimes
required for specially designed parts or for repair
of worn or improperly machined parts.10 After
electroplating, a final rinse tank is used to
remove as much of the electrolytic solution as
possible from the parts. The items are then
dried. The rack or barrel is then sent to an
unloading station, where the parts are inspected
and removed from their loading devices.
The large number of electrolytic solutions
used in the electroplating process can be
modified with various additives. The thousands
of different additives used are mostly
proprietary, but can include the following:
organic additives such as gelatin, milk, sugar,
molasses, various aldehydes, coumarin, dextrin,
furfural, and some sulfonic acids; and metallic
additives such as selenium, cobalt, nickel, and
molybdenum.11 Brighteners and grain refiners
are often added to the electrolytic solution to help
control the metal crystal growth on the substrate.
Brush Plating
Brush plating is another metal deposition
process used to electroplate a metal coating on a
substrate, primarily in more specialized
operations. For example, brush plating is used
to repair and salvage molds, dies, shafts, and
housings that are used in the heavy duty
machinery and tools industry. A big advantage
to brush plating is that it can be accomplished in
the field without having to disassemble the
damaged part. The brush electroplating process
uses a portable stylus as the anode, the substrate
as the cathode, and a direct-current power
source. An absorbent material that contains the
110
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CHAPTER 6: ELECTROPLATING
TABLE 6.1 PRICES OF COMPOUNDS USED IN ELECTROLYTIC SOLUTIONS
Chemical
Price ($/lb)
Cadmium Chloride
Cadmium Oxide
Cadmium Sulfate
Chromic Acid
Nickel Carbonate
Nickel Chloride
Nickel Sulfamate
Nickel Sulfate
Potassium Cyanide
Sodium Bichromate
Sodium Cyanide
Sulruric Acid
68.48a
N/A
38.403
1.22
3.40
1.60
N/A
1.06
1.76 to 1.84
0.60
0.60
0.04
Source:
Chemical Marketing Reporter, February 7, 1994
* $/gal, 20 percent solution
N/A: Not Available
Cadmium
Cadmium is widely used as a coating for the
protection of steel and iron parts and historically
has been the highest-priced metal that is
commonly electroplated.3 Cadmium is the
preferred choice for metal items that have to
endure highly corrosive environments, such as
marine or damp operating conditions. Besides its
excellent corrosion resistance, cadmium is used
in electroplating for its good solderability,
ductility, retention of luster, its low coefficient of
friction, and ease of deposition.4 Cadmium
produces a dull, easily tarnished coating and is
rarely used as a decorative finish. Cadmium
plate is resistant to alkaline compounds, but
dissolves in most mineral acids.
Chromium
A chromium coating imparts a bright, highly
reflective surface that has exceptional wear-
resistant properties and high corrosion
protection.5 Chromium is almost exclusively
plated over a nickel or copper/nickel undercoat
for decorative or "bright" applications. The
chromium prevents the nickel from tarnishing to
a greenish or yellowish color and provides the
nickel plating a higher wear resistance.6 The
nickel in turn helps give chromium the;bright
white color.7 When high wear resistance of a
part is required, a thick or "hard" chromium
coating can be plated directly onto the metal. A
chromium coat is reactive with the halogens and
can be dissolved in halogen acids and sulfuric
acid. Chromium coats are resistant to nitric acid
and aqua regia.
Nickel
Nickel is used as a coating for decorative,
engineering, and electroforming purposes. It is
the closest to being considered the "all-purpose"
metal for electroplating because the properties of
electroplated nickel can be controlled and varied
over a wide range.8 Nickel can be electroplated
onto a substrate to produce fully-bright, semi-
bright, or satin-like decorative surfaces. Nickel,
however, tarnishes in urban atmospheres and is
usually plated over with chromium when
appearance is important. Nickel is used for
engineering purposes to improve the corrosion
resistance, wear resistance, and magnetic
109
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PART O: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
produce the corrosion resistant surfaces
traditionally required for engineering purposes.19
Nickel in solution is in the Ni(II) state.
In the Watts bath, the electrolyte is a mixture
of nickel sulfate and nickel chloride. This
produces a coating with a low hardness and high
percent elongation. The Watts bath has an
average nickel metal concentration of 80 g/1 and
an average current density of 50 ASF.
Nickel chloride is commercially formed by
dissolving nickel metal in hydrochloric acid,
followed by crystallization. Nickel sulfate is
produced mostly as a by-product of electrolytic
copper refining and by dissolving nickel metal in
sulruric acid.20
In the all-chloride bath, a nickel chloride
electrolyte is used at a concentration of 300 g/1,
which equates to 75 g/1 of nickel metal. The
average current density of the all-chloride bath is
50 ASF. This produces a hard coating with a
high internal stress. As with the Watts bath, the
nickel chloride is manufactured by dissolving
nickel metal in hydrochloric acid, then
crystallizing.21
The sulfamate bath uses nickel sulfamate
at a concentration of 350 g/1 as the electrolyte
(65 g/1 of nickel metal). The average current
density of 37 ASF is the lowest of the three
common nickel plating baths. The sulfamate
bath produces a plating with a very high tensile
strength and low internal tensile stress. The
Ni(II) sulfamate solution is formed by dissolving
nickel powder into hot sulfamic acid. Ni(II)
ammonium sulfate was used in the past for
electroplating baths, but its use is very limited
in industry today.22
ENVIRONMENTAL RELEASES OF 33/50
COMPOUNDS FROM ELECTROPLATING
^PROCESSES
Environmental releases of the 33/50 metals,
metal compounds, and cyanide compounds
associated with their use in the electroplating
process occur from their refining or production
through to the electroplating process and the final
disposal of plated products. The following
sections present the environmental releases from
the production of these compounds and the
releases from the actual electroplating process.
Environmental Releases from Refining or
Production of the 33/50 Metals, Met&l
Compounds, and Cyanide Compounds
Releases and transfers of the 33/50 metals and
metal compounds from the primary non-ferrous
metals industry reported in the 1991 TRI were
discussed in Chapter 1. Total environmental
releases and off-site transfers of cadmium,
chromium, nickel, and their compounds were
about 692 thousand pounds. Using a life cycle
perspective, some fraction of these production
releases can be associated with the electroplating
industry. Similarly, some of the releases of
cyanides from facilities that produce hydrogen
cyanide, sodium cyanide, or potassium cyanide
are associated with the use of these chemicals in
electroplating baths. The 1991 releases and
transfers of hydrogen cyanide and sodium
cyanide from production facilities were discussed
in Chapter 4 and totalled more than 1.4 million
pounds. Most (90 percent) of these releases and
transfers were from the production of hydrogen
cyanide. Hydrogen cyanide is not used in
electroplating baths, but about ten percent of the
hydrogen cyanide produced is used to
manufacture sodium and potassium cyanide (see
Figure 4.1).
Releases and transfers of 33/50 metals, metal
compounds, and cyanide compounds associated
with the electroplating process also occur from
the production of the inorganic metal salts or
other metal compounds (like chromic acid) used
in the plating bath. Inorganic chemical
manufacturing facilities are classified under SIC
2819 and are required to report their releases in
TRI. The 1991 TRI data for releases and
transfers of cadmium, chromium, and nickel
compounds from SIC 2819 are presented in
Table 6.2. Almost 10 million pounds of
cadmium, chromium, nickel, and cyanide
compounds were released or transferred to the
environment from SIC 2819 in 1991.
Approximately 96 percent of these releases were
chromium compounds released on-site to land-
112
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CHAPTER 6: ELECTROPLATING
electrolyte covers the anode. The stylus is
rubbed over the region to be plated (the cathode).
which closes the DC circuit.12 Nickel plating is
often done by the brush electroplating method.
Cadmium Plating Baths
The most common method to electroplate
cadmium is with an alkaline cyanide bath.
Cadmium is supplied to the bath in the form of
metallic cadmium or cadmium compounds like
cadmium oxide, cadmium cyanide, cadmium
sulfate, and cadmium chloride. An all-purpose,
bright cadmium bath has a sodium cyanide to
cadmium ratio of 5:1, with typical ratios ranging
from 4:1 to 7.2:1. Sodium hydroxide and
sodium carbonate are also used in the bath
solution. Operating temperatures range from 24
to 32°C. For uniform plate thicknesses, a
current density of 20 to 40 amperes per square
foot (ASF) is typically recommended. However,
current densities can range from 5 to 70 ASF,
with higher values used for higher speeds and
efficiencies.13 These higher speed operations
also require agitation and cooling of the bath.
Cadmium oxide is produced either by the
evaporation of cadmium metal and oxidation of
the vapor or by the thermal decomposition of
cadmium nitrate. Cadmium cyanide is produced
by the evaporation of a mixture of dilute cyanic
acid and cadmium hydroxide or the precipitation
from a solution of cadmium salt and alkali-metal
cyanide. Cadmium sulfate is made by melting
cadmium metal with ammonia or sodium
peroxodisulfate. Cadmium chloride is
manufactured by reacting molten cadmium with
chlorine gas or vaporizing a solution of cadmium
metal and hydrochloric acid. The use of
cadmium chloride is declining in industry today,
but the salt is still occasionally used in
electroplating baths.14
Chromium Plating Baths
The equipment and electrolytic solutions used
to obtain either a thin and bright, or thick and
hard chromium coating are essentially the same.
The most common chromium plating bath,
known as the conventional or ordinary bath, is a
sulfate plating bath with a hexavalent chromium
electrolyte. Chromium(VI) is added to the
electrolytic solution as chromic trioxide (CrO3),
which forms chromic acid (H2CrO4) when
dissolved in the aqueous solution. The chromic
acid concentration in solution is usually
maintained at between 250 to 400 grams per liter
(g/1). The sulfate concentration is usually kept
constant by adding sulfuric acid or a sulfate salt,
with the bath maintained at a chromic acid to
sulfate ratio of 100:1 to 125:1,15 Varying this
ratio effects the throwing and covering power,
current density, deposition rate, and deposition
brightness.
The difference between bright and hard
chromium plates lies in the dissimilar solution
temperatures, current densities, and plating
times. For a bright chromium coating, the
operating temperature is kept in the range of 32
to 43°C, the current density is 100 to 200 ASF,
and a plating time of 0.5 to 5 minutes is usually
sufficient. To obtain a hard coating, an
operating temperature of 37 to 65°C is used, the
current density can be 150 to 350 ASF and a
much longer plating time of 20 to 2,160 minutes
is needed.16
The chromium(VI) oxide that is used in the
chromium plating electrolytic solution is
generally produced by an acid reaction. Sulfuric
acid is reacted with sodium bichromate, forming
a precipitate, which is filtered out of the solution
and heated to recover the chromium(VI) oxide.
A recently developed process eliminates the use
of acid by using an electrochemical cell and
sodium dichromate.17
Nickel Plating Baths
The three most commonly used nickel
electroplating methods are the Watts, all-
chloride, and sulfamate baths, though in recent
years the use of the all-chloride bath has been
limited to more specialized applications.18 All
three methods utilize the same basic inorganic
electrolyte compounds - nickel sulfate, nickel
chloride, and boric acid - with varying organic
additives to effect the plate properties. Organic
additives are used to produce the protective,
mirror-bright, smooth surfaces required for
decorative metal coatings. Pure nickel is used to
111
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
based facilities. Like the releases from the
primary metals industry or hydrogen and sodium
cyanide production facilities, only a fraction of
these releases can be attributed to the use of
these chemicals in electroplating.
Environmental Releases of 33/50 Metals and
Cyanides from Electroplating
Environmental releases of metals, metal
compounds, and cyanide compounds that are
directly attributed to the electroplating process
include releases from job shops classified under
SIC 3471 (the plating and polishing industry) and
releases from manufacturers who perform
electroplating on their own products in captive
shops. Releases and transfers of 33/50 metals
and cyanide compounds from SIC 3471 reported
in the 1991 TRI are presented in Table 6.3.
Releases and transfers from manufacturers who
perform captive electroplating are listed under
the SIC code for the manufacturer's product
instead of SIC 3471. No attempt was made to
obtain this data from the TRI database since
releases from the electroplating process cannot
be distinguished from releases from other
product manufacturing processes.
On-site releases of chromium compounds to
land accounted for almost 73 percent of the total
releases and transfers of the 33/50 compounds
from the plating and polishing industry. Off-site
transfers were also significant. Metal-laced
sludges generated as a by-product of the
electroplating process are classified under the
Resource Conservation and Recovery Act
(RCRA) as hazardous wastes.
On-site air releases can result from
evaporation of the electrolytic solution and
misting from plating tanks. Rinse water is the
main source of wastewater from the
electroplating process. Other sources of on-site
water releases include effluent from treating
spent electroplating solution, spills, and solution
carry-over. Treatment and disposal of spent
plating solutions is a primary source of
hazardous waste from electroplating. Off-site
transfers include electrolytic sludge from
wastewater treatment and plating tanks. POTWs
receive the effluent from wastewater treatment
facilities treating plating rinse water.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
Worker health and safety are a significant
concern in the electroplating industry. As
discussed previously, hexavalent chromium is
classified by EPA as a human carcinogen;
cadmium is classified as a probable human
carcinogen; nickel dust is classified as a human
carcinogen. Cyanide compounds are acute
poisons. All of these compounds are toxic
chemicals that cause both acute and chronic
health effects.
Exposure to cadmium, chromium, and nickel
as salts, dust or fumes and cyanides can occur
from their use in metal plating and coating.
Occupational exposure is a particular problem
with chromium plating baths where large
quantities of hydrogen are evolved at the cathode
and of oxygen at the anode. As the gases break
the surface of the bath, they carry bath
constituents like chromic acid as a mist. The
mists are typically controlled by a tank
ventilation system coupled to a scrubber.
OSHA has established occupational exposure
limits for cadmium, chromium, nickel, and
cyanides. The 8-hour time weighted average
PEL is 0.2 milligrams per cubic meter (mg/m3)
for cadmium dust and 0.1 mg/m3 for cadmium
fumes. The PEL established by OSHA for
nickel metals and soluble nickel compounds and
chromium metal and insoluble chromium salts is
1.0 mg/m3. OSHA has established a PEL of 5
mg/m3 for cyanide as the CN' moiety.
At least one study has assessed the health
status of workers exposed to cyanide fumes and
aerosols in a factory during electroplating and
case-hardening jobs. The highest levels of
cyanide measured in the work environment were
0.8 and 0.2 mg/m3 in the breathing zone and the
general workroom atmosphere, respectively.
114
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CHAPTER 6: ELECTROPLATING
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113
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
The workers complained of typical symptoms of
cyanide poisoning like headache, weakness,
changes in taste and smell, irritation of throat,
abdominal colic, and nervous instability.23
Metal compounds can enter the water
environment from plating operations when spent
plating solutions and rinse water are discarded,
and can enter the air by the evaporation and
misting of plating solutions.24 In the past,
electroplating shops have been the source of
substantial quantities of toxic chemicals in the air
and water in industrial areas. In the 1970s, New
York City emitted 485 tons per year of
chromium. Approximately 43 percent of the
daily chromium burden in the New York City
sewer system and 24 percent of chromium vapor
emissions to New York City air were from
electroplating wastes.25
EPA has established effluent guidelines and
standards for electroplating. The standards limit
the concentrations of cyanides, chromium, lead,
and nickel that can be discharged in effluent
from electroplating facilities. These standards
divide electroplating facilities into two
categories: facilities that release less than 10,000
gallons per day and facilities that release 10,000
gallons per day or more. The smaller facilities
must meet the pretreatment standards for existing
sources (PSES) that limit the daily maximum
discharge of cyanide amenable to chlorination to
5.0 milligrams per liter (mg/1), of lead to 0.6
mg/1, and of cadmium to 1.2 mg/1. The larger
facilities must meet the same effluent standards
for cadmium and lead, plus additional standards
for nickel (4.1 mg/1), chromium (7.0 mg/1),
copper (4.5 mg/1), zinc (4.2 mg/1), total cyanides
(1.9 mg/1), and total metals (10.5 mg/1).26
EVALUATION OF SUBSTITUTES
Safe substitute approaches to reducing the use
of 33/50 metals and cyanide compounds in
electroplating include the following:
• product redesign to eliminate unnecessary
rnetal coatings;
• using alternative metal deposition technologies
that do not require a plating bath; and
• using safer, less toxic metals or plating bath
solutions in the electroplating process.
The first two approaches probably have the
greatest potential for reducing the overall
environmental releases of 33/50 compounds from
metal plating operations, since they eliminate
part or all of the metal plating process. Using
safer, less toxic metals or plating bath solutions
will reduce the adverse health and environmental
effects that can result from electroplating, but
may not significantly reduce the amount of
hazardous waste generated. Most wastewater
treatment sludges from electroplating operations
are listed as hazardous wastes under RCRA.
In some cases, a product can be redesigned
to eliminate the need for a metal plated surface.
When product redesign is not feasible, a viable
alternative may be a metal deposition technology
that does not use a plating bath. Another
option is to substitute less toxic metals or plating
bath solutions for the 33/50 metals or cyanide-
based solutions.
Redesigning the Product
In some instances, the use of metal plating for
a component can be eliminated, and it will not
adversely affect the part's performance or
marketability. Products can be redesigned to
eliminate decorative metal plates, use other
methods to provide desired coating
characteristics, or use substrate materials that do
not require plating.
Decorative metal plating is used on all types
of products, from the trim on household products
to automobile bumpers and interiors.
Eliminating the use of metal coatings when they
are used for purely decorative reasons would
result in an immediate reduction in the
generation of hazardous waste. This can be
accomplished by using an alternative finish like
powder coatings (see Chapter 8) or eliminating
the final coating altogether.
116
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CHAPTER 6: ELECTROPLATING
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115
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
substrate contact is so intimate that free electron
exchange occurs resulting in an atomic weld.
The metals that can be mechanically plated must
be ductile and include zinc, cadmium, tin, lead,
copper, brass, aluminum, silver, indium, and
gold.
A unique characteristic of mechanical plating
is the ability to easily apply combination, alloy,
and layered coatings of two or more metal
powders. Plate thickness is not controlled by the
length of time the substrate is in the barrel of a
mechanical plater, but by the amount of metal
powder added to the barrel. Generally,
mechanical plating is suited for parts that are
normally batch handled, having no greater
dimensions than 10 to 12 inches in length, and
weighing less than two pounds. Bolts up to 40
inches long have been successfully mechanically
plated. Parts with deep recesses or blind holes
which trap the glass beads are not usually suited
for the process.30
Vacuum Metallizing. Vacuum metallizing,
which includes vacuum evaporation, sputtering,
and ion plating, is another method that applies
functional and decorative metal coatings to
substrates without the utilization of a bath
solution. Vacuum evaporation uses a vacuum
chamber in which the parts to be plated are
mounted. The pressure in the chamber is
reduced to less than one millionth of an
atmosphere. The metal to be plated is heated in
excess of its boiling temperature to create a
vapor pressure considerably higher than the total
pressure in the chamber. The metal travels in
vapor form into the vacuum chamber and coats
the first surface it comes in contact with, i.e., the
substrate. The best known and largest used
application of vacuum evaporation is the
decorative jewelry business where very thin,
brilliant films (aluminum) are deposited on
plastic or metal substrates.
Sputtering also takes place in a vacuum
chamber. In this process a gas plasma discharge
is set up between two electrodes, a cathode
plating material, and an anode substrate.
Positively charged gas ions are attracted to and
accelerated into the cathode. The impact knocks
off atoms of the cathode, which impact the anode
and thus plate the substrate. Ion plating
combines these processes in a third vacuum
metallizing application. The substrate to be
plated is charged to be the cathode while the
coating metal becomes the anode. Vacuum
evaporation is limited to a single element,
traditionally aluminum; sputtering allows for a
wide variety of metals, alloys, and compounds.31
Other Metal Deposition Processes.
Additional metal deposition processes include
chemical vapor deposition and cladding.
Chemical vapor deposition is a process for
coating a preheated part with the vaporized
compounds of metallic salts. The process is also
known as gas plating or pyrolitic plating.
Cladding is the process of bonding powdered
metal or metal sheet to a base metal by a
combination of heat and pressure. Cladding is
commonly used to produce gold-clad brass
jewelry.
Using Safer, Less Toxic Metals and Plating
Baths
In many cases, a plating-bath-electroplating
process is required to achieve performance or
appearance requirements. In these cases,
substitute metals or plating bath chemistries can
be used to reduce the toxicity of the plating bath
and the risk to human health and the
environment. Several chemical substitutes have
been identified for the 33/50 metals and cyanides
used in electroplating. Many of these substitutes,
like zinc substitutes for cadmium, have long been
recognized as viable substitutes for some
applications of the toxic metals.
Cadmium Substitutes. Zinc can be used to
replace cadmium in many electroplating
applications. Zinc, however, is not as corrosion
resistant as cadmium, forms unsightly white
corrosion stains, and has poor solder ability. A
tin-zinc alloy can be used to increase the
solderability of the coating and to increase the
corrosion resistance. A zinc-nickel alloy has
also been tested as an alternative to cadmium
plating in marine environments. Preliminary
investigations show zinc-nickel affords corrosion
protection to steel and ferrous metals in marine
environments comparable to that of cadmium.32
118
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CHAPTER 6: ELECTROPLATING
Metallic-ceramic coatings have also had
success replacing plated cadmium in particular
applications. The metallic-ceramic coatings,
using zinc, aluminum, or alloys of these metals,
possess the corrosion resistance characteristic of
cadmium, without the environmental issues.
Further comparisons of this alternative are
presented in Table 6.4. To date, metallic-
ceramic coatings have successfully replaced
cadmium in more expensive military
applications, including landing gear axles of
modern aircraft, gas turbine-engine compressor
sections, and allied parts.33 In the future, the
positive environmental aspects of this alternative
may make it economically feasible in other
coating applications.
Cyanide Substitutes. Several non-cyanide
plating baths have been developed that can
reduce the amount of cyanides released to the
environment by cadmium plating. These include
the neutral sulfate, acid fluoroborate, and the
acid sulfate solutions. These baths have a higher
cathode efficiency than the traditional cyanide
bath and cause less hydrogen to be generated
during the electroplating process. Thus, the
danger of hydrogen embrittlement is reduced and
the potential for toxic releases to the environment
due to misting is reduced. The compositions and
operating conditions for these three alternative
baths, compared with a traditional alkaline
cyanide bath, are presented in Table 6.5.34
In the gold plating process, a sulfate plating
bath can be substituted for the cyanide bath. The
gold-cyanide solution is the most common
method for the plating of gold, especially in the
circuit board industry, but it is considered
acutely toxic by EPA. A study performed at the
Sandia National Laboratories compared the
coatings produced on microelectronic circuits by
the gold-cyanide and gold-sulfate processes. The
test results showed that sulfate gold plating
solutions are compatible with a wide variety of
substrates used in microelectronic circuits
including quartz, aluminum oxide, silicon, glass,
cordierite, duroid, and gallium arsenide.
Compatibility with surface treatment compounds
was also shown in the study. The sulfate bath
formed a gold plate that had a similar weld bond
strength and produced a coat density that was
very close to pure gold. The study concluded
that the gold-sulfate bath was much less
hazardous than the gold-cyanide bath and
produced nearly equal, if not slightly better,
coatings.35 This application is now commercially
available.
TABLE 6.4 COMPARISON BETWEEN METALLIC-CERAMIC COATING AND CADMIUM
PLATE
Thickness ranges possible
Size of part
Inside/blind holes
Sacrificial
Potential
Electrical conductivity
Hydrogen embrittlement
Temperature of use
Lubrication
Use with paint systems
Metallic-Ceramic
wide range
unlimited
can be coated
yes
0.74v
yes
no
> 537°C
requires wax
compatible
Cadmium
limited
limited to tank
unlikely
yes
0.76 v
yes
possible
limited
self-lubricating
compatible
Source:
William B. McCune, "Coatings Without Cadmium," Machine Design, July 23, 1993, p. 50, 53
119
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PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
TABLE 6.5 COMPARISON OF NON-CYANIDE CADMIUM ELECTROPLATING BATHS
Bath Component (g/1) or
JDperating Condition
Ammonium Chloride
Ammonium Fluoborate
Ammonium Sulfate
Boric Acid
Cadmium
Cadmium Fluoborate
Cadmium Oxide
Sodium Carbonate
Sodium Cyanide
Sodium Hydroxide
Sulftiric Acid
Current Density, ASF
JTemperature, C
Alkaline
Cyanide
_
-
-
_
20.2
.
22.5
30.0 to 59.9
101.1
14.2
5 to 90
16 to 38
>— — _ ^ mm— _ .
Neutral
Sulfate
11. 2 to 22.5
14.9 to 112.3
3.7 to 11.2
.
.
2 to 15
16 to 38
Acid
Fluoborate
— — ^— — — ^— — .^».
59.9
27.0
94.4
241.2
30 to 60
21 to 38
— ^— — _
Acid
Sulfate
7 5 to 1 1 9
/ "J \\J I I .L,
4.5 to 5.0
10 to 60
16 to 32
Source:
Metal Finishing 61st Guidebook and Directory, Vol. 91, No. Al, 1993, p. 177
Acid chloride and alkaline non-cyanide
electroplating baths can be substituted for the
traditional cyanide bath used in zinc
electroplating, depending on the substrate to be
plated. In general, acid baths are compatible
with more substrates, including malleable, high
carbon, heat treated, and carburized substrates.
These alternative bath solutions are relatively
non-toxic to humans, but the acid chloride bath is
corrosive to equipment.36 The Peerless Chain
Company of Winona, Minnesota successfully
converted their zinc cyanide plating operations, a
three-barrel-line and one continuous plating line,
to an alkaline zinc plating operation. The loss of
intrinsic cleaning qualities of cyanide solutions,
the most significant drawback in Peerless1
experience, was compensated for by adding an
alkaline electrocleaning process prior to plating.
One advantage of the alkaline, non-cyanide
system was the possibility, after filtration, to
reuse treated water back in the plating syrxm.37
Electroless plating, also called autocatalytic
chemical plating, is an alternative plating
technology that eliminates the cyanide bath and
the electrical current of traditional electroplating
operations. Metal ions in an aqueous solution
are chemically reduced (plated) on the catalytic
surface of the substrate. The substrate can be a
variety of materials (e.g., plastics, metals, and
fabric) and is prepared with a thin catalyst film
activated by heat or light which, when
submerged in the plating solution, initiates the
plating process. Metal ions from solution,
accepting electrons from reducing agent(s) in
solution, are deposited on the catalyzed substrate
surface. After the first molecular layer is
deposited, the metal then acts as the catalyst to
promote further deposition. Metals which can be
plated using this technique include nickel,
copper, gold, palladium, and cobalt. Solutions
chemistries include alkaline and acid baths with
various complexing, reducing, and stabilizing
agents.38
A similar metal deposition process,
immersion plating, also uses chemical reduction
to accomplish metal plating. However, in
immersion plating the reducing agent is the base
metal and not a chemical additive. The base
120
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CHAPTER 6: ELECTROPLATING
metal is displaced by another metal ion in
solution with a lower oxidation potential than the
displaced metal. Deposit-base metal pairs that
can utilize this plating technique without a
cyanide solution are presented in Table 6.6.39
Chromium Substitutes. Less toxic trivalent
chromium (Cr(III)) has been shown to be an
effective replacement for the hexavalent (Cr(VI))
structure when a thin, bright chromium plating
is required. The coating produced by Cr(III)
can vary in appearance from the normal
chromium bluish-white to a deep-looking pewter
finish, and will not stain if some solution is left
on the part. Trivalent chromium can be used for
decorative plate and corrosion resistant plating.40
Due to limitations in plate thicknesses, however,
wear-resistant trivalent chromium plate is not
possible.
TABLE 6.6 METAL PARINGS FOR NON-CYANIDE IMMERSION PLATING BATHS
Type of Deposit
Bronze
Cadmium
Copper
Gold
Nickel
Silver
Tin
Zinc
Base Metal
Steel
Aluminum
Copper alloys
Steel
Aluminum
Steel
Zinc
Copper alloys
Copper alloys
Steel
Zinc
Copper alloys
Aluminum
Copper alloys
Steel
Zinc
Aluminum
Steel
Bath Ingredients
Stannous Sulfate, Copper Sulfate, and Sulfuric Acid
Cadmium Sulfate and Hydrofluoric Acid
Cadmium Oxide and Sodium Hydroxide
Cadmium Oxide and Sodium Hydroxide
Copper Sulfate and Ethylenediamine or Hydrofluoric Acid
Copper Sulfate and Sulfuric Acid
Copper Sulfate, Tartaric Acid, and Ammonia
Hydrogen Tetrachloroaurate and Ethanol
Nickel Sulfate, Ammonium Nickel Sulfate, and Sodium
Thiosulfate
Nickel Sulfate
Nickel Sulfate and Sodium Chloride
Silver Nitrate, Ammonia, and Sodium Thiosulfate
Sodium Stannate
Stannous Chloride, Thiourea, and Sulfuric Acid
Stannous Sulfate and Sulfuric Acid
Stannous Chloride
Zinc Oxide and Sodium Hydroxide
Zinc Chloride and Ammonium Chloride
Source:
Metal Finishing 60st Guidebook and Directory, Vol. 90, No. Al, 1992, p. 368-372
121
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Besides reduced toxicity, Cr(HI)
electroplating has a number of advantages over
Cr(VI) electroplating. Trivalent chromium has
a greater throwing power, covering power,
tolerance to current interruptions, and ease of
rinsing than Cr(VI).41 As shown in Table 6.7 the
trivalent system also has a lower concentration of
chromium than the hexavalent system, which
results in less sludge volume upon disposal.42
Further, Cr(III) electroplating processes are
typically easier than Cr(VI) processes and
require less trouble-shooting. Evolution of
Cr(VI), which has been identified as a possible
drawback to this process, can be significantly
controlled by chemical additives or the addition
of a secondary anode in solution. The Cr(III)
process uses the exact same equipment as the
Cr(VI) bath, making it a drop-in replacement.
TABLE 6.7 CHROMIUM PLATING TYPICAL OPERATING CONDITIONS
Chromium, g/1
PH
Temperature, °C
Cathode current density, ASF
Agitation
Rectifier voltage
Anode-cathode ratio
Anode material
Single-cell
Double-cell
Chromium concentration, g/1
Single-cell
Double-cell
Maiximum thickness, mil
Single-cell
Room temperature
High temperature
Double-cell
Plating rate, mil per min
Single-cell (constant)
Room temperature
High temperature
Double-cell (average)
Trivalent Chromium
5 to 25
2.3 to 4.0
70 to 120
40 to 150
Mid-air
4 to 15
2:1
Carbon
Lead, 7 percent tin
4 to 20
5 to 10
about 0.05
1 or more
about 0.01
0.005 to 0.007
0.007 to 0.010
0.004 or less
— — _
Hexavalent Chromium
100 to 200
Less than 1
32 to 49
175 to 300
Optional
4 to 12
I:lto3:l
Lead, 7 percent tin
150 to 300
5 or more
0.005 to 0.007
Source:
Metals Finishing 61st Guidebook and Directory, Vol. 91, No. 1 A, 1993
122
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CHAPTER 6: ELECTROPLATING
A plated tin-cobalt alloy that looks like
chromium is another alternative to chromium
plating for decorative applications. The process
provides a tin-cobalt plate that matches the
appearance of bright chromium with a hardness
and wear resistance that is sufficient for most
indoor, decorative applications. Table 6.8
compares the plate quality and operating
parameters of the two electroplating chemistries.
The tin-cobalt plate appearance, ranging from
a bright chromium appearance to a warm silvery
gray color, is controlled by varying the percent
of tin in the metal alloy. The process, either
rack or barrel, uses an alkaline sulfate system
with optional wetter/amine-based liquid
brighteners. To achieve the appearance of a
chromium plate, the optimal tin:cobalt ratio in
solution, is 50:50. This results in a plate that is
80 percent tin and 20 percent cobalt. Decreasing
the cobalt content of the plate below 17 percent
results in a mat gray appearance. Additional
operating conditions include a pH of around 8.5,
and an operating temperature between 38 and
43°C. Current applications of this plating
alternative for chromium include automotive
interior parts, computer components, bicycle
spokes, flexible shower hoses, and screws.43
Nickel Substitutes. The versatility of nickel
as a metal coating makes it difficult to replace,
but the use of nickel can be lowered by using
metal alloys. A nickel-iron alloy that contains up
to 40 percent iron is used in decorative
applications to provide a coating similar in
appearance to bright nickel, but without
equivalent corrosion resistance. An alloy with
35 percent nickel and 65 percent tin has excellent
corrosion resistance. An alloy with 35 percent
nickel and 65 percent tin has excellent corrosion
resistance, but only retains this property as long
as either bronze, copper, or steel is used as an
undercoat. The nickel-tin alloy does not have the
intrinsic brightness of nickel plate, but it can be
mechanically brightened to obtain a similar
appearance. Unfortunately, most electroplating
alloys are more brittle than their pure
counterparts, limiting their versatility.44
TABLE 6.8 COMPARISON BETWEEN TIN-COBALT AND DECORATIVE CHROMIUM
Tin-Cobalt
Chromium
Appearance
Corrosion resistance
Wear resistance
Tarnish resistance
Solderability
Metal coverage in recesses
Cathode efficiency
Current density (ASF)
Chemical nature
Barrel production
Good
Good
Good
Good
Good
Excellent
90 to 95 percent
1.9 to 13.9
Neutral and non-corrosive
Conventional barrel plating
Good
Excellent
Excellent
Excellent
Not possible
Fair
15 to 20 percent
139.4 to 371.8
Acidic and corrosive
Special equipment and slow
production
Source:
Tamara Davidson, "Safe, Environmentally Clean Alloy Replaces Chromium," Design News, Vol. 46, December
1990
123
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Conclusions
The complexity of electroplating operations
and the various plating baths used in the
electroplating process makes it difficult to
identify across-the-board substitutes. Substitutes
are available, however, to reduce the use of the
toxic 33/50 metals, metal compounds, and
cyanides in many applications. Product redesign
to eliminate the use of electroplating is the best
environmental alternative, since it eliminates the
use of both the metal and the toxic plating bath.
Products are already being redesigned in some
industries, like the printed circuit board industry,
to eliminate electroplating. Decorative
electroplating is also being replaced in some
industries by paints and coatings.
Metal deposition methods that do not use a
plating bath are probably the next choice from an
environmental standpoint. These methods
eliminate the hazardous plating bath, but not the
use of the toxic metal. One drawback to the
alternative metal deposition methods is that metal
overspray from spraying methods or tailings
from remachining thick coatings may actually
increase the consumption of metal and the
occupational hazards. Thus, alternative metal
deposition methods should not be substituted for
electroplating without evaluating the potential
health and environmental consequences of
substitution.
Finally, safe substitutes for the 33/50 metals
do exist. Zinc, tin-zinc, tin-cobalt, and other
alloys have been shown to be effective substitutes
for decorative and some functional applications.
An advantage of these alternatives is that many
of the bath solutions do not use cyanide.
Experimentation and cooperation with vendors
and suppliers of electroplating
equipment/chemicals is an effective means
of identifying alternatives to effectively replace
the 33/50 chemicals and metals used in
electroplating.
124
-------
-------
16 Jeff Shular, et. al. , Locating and Estimating Air Emissions from Sources of Chromium
(Supplement). (Springfield, VA: US Department of Commerce, 1989)
nr,** £?£*?' et-^;'^°lt]gang Gerham' *" "Chromium Compounds," Ullmann's Encyclopedia
of Industrial Chemistry, (Wemheim, Germany: VCH Verlag., 1985).
17 Gerd Anger, et. al., Wolfgang Gerhartz, ed., "Chromium Compounds," Ullmann's
Encyclopedia of Industrial Chemistry, (Weinheim, Germany: VCH Verlag., 1985).
JMV /x?aV!dnBe,nJamin> Cd" "Industrial Applications of Nickel Plating," Metals Handbook: Ninth
tdition, (Metal Park, Ohio: American Society for Metals, 1980).
19 Metal Finishing 61st Guidebook and Directory, Vol. 91 , No. 1 A, 1993.
fr ^ "K^ Lascelles' et- *- Wolfgang Gerhartz, ed., "Nickel Compounds," Ullmann's Encyclopedia
of Industrial Chemistry, (Weinheim, Germany: VCH Verlag. , 1985). wyciopeaa
21 Ibid.
22 Ibid.
23
24
25
"Hydrogen Cyanide," Hazardous Substances Data Bank, April 22, 1992.
"Cadmium," Hazardous Substances Data Bank, August 23, 1990.
"Chromium," Hazardous Substances Data Bank, August 23, 1990.
Htee US^pfS ^f P^ ^^ ^^/^ Lead and Cadmium in Products in Municipal Solid
waste, US EPA, Office of Pollution Prevention and Toxics, (Washington DC, 1992).
28 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1A, 1993.
29 Marvin Rubinstein, Electrochemical Metallizing: Principles and Practices, (New York- Can
Nosti and Reinhold Company, 1987).
30 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1A, 1993.
31 Ibid.
" "Electrodeposited Zinc-Nickel as an Alternative to Cadmium Plating for AerosDace
Applications," NASA Technical Memorandum, July 1991.
33 William B. McCune, "Coatings Without Cadmium," Machine Design, July 23, 1993.
34 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1A, 1993.
35 Walter Worobey, et. al. , Mo Jamshidi, ed. , "Gold Sulfite Replacements of Cyanide Solutions "
Environmentally Conscious Manufacturing: Recent Advances, (Albuquerque, MM: ECM Press, 1992). '
126
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CHAPTER 6: ELECTROPLATING
36 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1A, 1993.
37 «
"Alternatives to the Use of Cyanide Solutions in Electroplating: Alkaline Non-Cyanide Zinc
Electroplating," Minnesota Office of Waste Management, July 1992.
38 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1A, 1993.
39 Metal Finishing 60st Guidebook and Directory, Vol. 90, No. 1A, 1992.
40 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1A, 1993.
41 Donald L. Snyder, "Decorative Chromium Plating," Metal Finishing: Guidebook and Directory
Issue '92, (Hackensack, NJ: Metal Finishing, 1992).
42 Metal Finishing 61st Guidebook and Directory, Vol. 91, No. 1 A, 1993.
"Environmentally Clean Alloy Replaces Chrome," Design News, Vol. 43, No. 23, December
43 <
1990.
44 F. A. Lowenheim, Guide to the Selection and Use of Electroplated and Related Finishes, (Ann
Arbor, MI: American Society for Testing and Materials, 1982).
127
-------
-------
CHAPTER?
PLASTICS AND RESINS
Products made from plastics and resins have
become an integral part of modern life. Almost
60.6 billion pounds of plastics and resins were
sold by U.S. manufacturers in 1991, down
slightly from 61.3 billion pounds in 1990.l In
1993, sales figures for plastics and resins
increased to more than 68.8 billion pounds for
U.S. manufacturers.2 Assuming that exports and
imports are roughly in balance, that equates to
more than 200 pounds per year of plastic for
every man, woman, and child in the U.S.
Since World War II the petrochemicals
benzene, toluene, and xylene have been the
basic building blocks of plastics and resins. The
toxic effects of these 33/50 chemicals and the
ever increasing solid waste disposal problem
have prompted increased research and
development into starch-based and sugar-based
degradable plastics.
The advent of the plastics industry followed
World War II, when petroleum supplies were
plentiful and the development of products made
from petroleum flourished. Today, the 33/50
chemicals benzene, toluene, xylene, and
hydrogen cyanide are among the basic building
blocks of the myriad plastics and resins in use.
Manufacturers of plastics release large quantities
of these chemicals to the environment.
Substantial reductions in the use of plastics and
resins, by using safe substitutes, could result in
an immediate reduction in certain releases of
these chemicals. This chapter presents the
production, use, and substitutes for products
made from polystyrene, one of the many plastic
resins made from the 33/50 chemicals.
INDUSTRY PROFILE
Polystyrene is a lightweight material obtained
from the polymerization of styrene monomer.
The styrene monomer is derived from benzene
which is produced by petroleum refining.
Polystyrene is used mainly in packaging,
disposables, and low-cost consumer goods.
The two common forms of polystyrene are
crystalline and foam. Crystalline polystyrene is
used to make yogurt and cottage cheese
containers, and clear clamshell containers like
those used at salad bars. In the foam form,
polystyrene is used by the food packaging
industry to manufacture cups, bowls, plates,
129
-------
PART H; PRIORITY PRODUCTS AND SIJRSTITT1TFC
cafeteria trays, and clamshell containers. Foam
polystyrene is also used to package electronics,
furniture, and other goods.
Polystyrene is further categorized as molding
grade, extrusion grade, or expandable bead
grade. Molding grade polystyrene is used in
durable or disposable consumer goods.
Extrusion grade polystyrene is extruded into
foam products or used with a blowing agent to
form expandable bead products like popcorn
packaging fill.
Polystyrene is a thermoplastic resin.
Thermoplastics are characterized by their ability
to be cooled and hardened, and then reprocessed
when reheated. This ability to be reprocessed
makes thermoplastic resins inherently more
recyclable than the other general category of
plastic resins, thermosetting resins.
Thermoplastics represent approximately 87
percent of the plastics and resins sold in the U.S.
Other thermoplastic resins include
polypropylene, polyvinyl chloride, and
polyethylene terephthalate.
Seventeen companies manufactured
polystyrene resins at 32 locations in the U.S. in
1992. Table 7.1 lists the producers of
polystyrene and their annual production
capacities. The following sections discuss the
quantities of polystyrene used in the various
polystyrene market segments and the price of
polystyrene.
Quantity of Polystyrene Used
In 1992 and 1993, polystyrene consumption
ranked fifth among the 23 major types of plastic
resins produced and marketed in the U.S.
Polystyrene consumption ranked behind low
density polyethylene, high density polyethylene,
polyvinyl chloride and copolymers, and
polypropylene and copolymers. Domestic
demand for polystyrene was about 5.1 billion
pounds in 1993, up from 4.9 billion pounds in
1992. Imports of polystyrene resin amounted to
105 and 137 million pounds for 1992 and 1993,
respectively, while exports were 317 and 340
million pounds for the same years.3 Both exports
and imports are up significantly from 1990 and
1991 figures. The quantities of polystyrene used
in 1992 and 1993 in molding grade, extrusion
grade, or expandable bead applications are
presented in Tables 7.2 through 7.4,
respectively.
Consumer demand for the low-cost product
markets for which polystyrene is used generally
follow the gross national product (GNP). The
decrease in polystyrene consumption experienced
between 1990 and 1991, however, exceeded the
decline expected based on the GNP. Market
sources attribute the downturn to environmentally
induced cutbacks.4 A stronger consumer market
contributed to the 4.7 percent rise in resin sale
between 1992 and 1993.5
Price of Polystyrene
Table 7.5 presents the price of polystyrene in
crystalline, molding, and expandable bead
grades. The prices are before the raw resin is
finished or transformed into an application use.
DESIRABLE PROPERTIES OF
POLYSTYRENE
The popularity of polystyrene is due, in part,
to its ability to be manufactured in crystalline or
foam form. Thus, polystyrene can be used in a
variety of applications. Either form can be
modified with additives to custom make the
polystyrene for a particular application.
Polystyrene can be made to be fairly chemically
inert, protect food products from an oxygen
atmosphere, retard food spoilage, and keep food
products warm. Polystyrene can also be used to
protect durable goods from mechanical damage.
Some of the current market development efforts
by polystyrene manufacturers are aimed at
improving impact strength and surface
appearance.6
130
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CHAPTER?: PLASTICS AND RESINS
TABLE 7.1 POLYSTYRENE RESIN PRODUCTION CAPACITY
1
Producer
American Polymers, Inc.
Amoco Corp.
ARCO Chemical Co.
3
BASF Corp.
Chevron Corp.
Dart Container Corp.
Deltech
Dow Chemical Co.
Fina
General Electric Co.
Huntsman Chemical Corp.
Kama Corp.
Mobil Oil Corp.
Monsanto Chemical Co.
Novacor Chemical Co.
Scott Paper Co.
Tenneco. Inc.
Location
Oxford, MA
Joliet, IL
Torrance, CA
Willow Springs, IL
Monaca, PA
Painesville, OH
South Brunswick, NJ
Marietta, OH
Owensboro, KY
Troy, OH
Gales Ferry, CT
Ironton, OH
Joliet, IL
Midland, MI
Pevely, MO
Torrance, CA
Carville, LA
Selkirk, NY
Belpre, OH
Chesapeake, VA
Peru, IL
Rome, GA
Hazelton, PA
Holyoke, MA
Joliet, IL
Santa Ana, CA
Addyston, OH
Decatur, AL
Leominster, MA
Springfield, MA
Fort Worth, TX
Citv of Industry, CA
TOTAL - —
1992 Capacity (million Ibs) '
60
210
35
70
475
70
175
480
66
100
135
180
235
280
130
250
640
70
390
440
255
45
35
80
480
70
160
320
120
200
90
55
6.401
International Directory of Chemical Producers, 1992: United States of America
131
SRI International
-------
PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
TABLE 7.2 POLYSTYRENE USES IN MOLDING GRADE APPLICATIONS
Application
Appliances/Consumer Electronics
Air Conditioners
Refrigerators & Freezers
Small Appliances
Cassettes, Reels, etc.
Radio/TV/Stereo Cabinets
Other
Furniture & Furnishings
Furniture
Toilet Seats
Other
Toys & Recreation
Toys
Novelties
Photographic Equipment
Other
Housewares
Personal Care
Other
JSuilding & Construction
Miscellaneous Consumer & Industrial
Footwear (heels)
Medical Equipment
Other
Packaging & Disposables
Closures
Rigid Packaging
Produce Baskets
Tumblers & Glasses
Flatware, Cutlery
Dishes, Cups, Bowls
Blow Molded Items
Other Injection
TOTAL MOLDING APPLICATIONS
Consumption
(million Ibs)
1992
28
65
36
267
157
10
32
9
11
123
46
56
7
74
88
50
7
85
16
— — — — __ __ ____
96
87
22
98
70
57
9
103
1.709
1993
30
78
40
290
176
12
34
9
12
130
52
63
9
82
96
56
7
95
20
105
96
27
96
90
63
10
1,888
Source:
Modern Plastics, January 1994
132
-------
CHAPTER?: PLASTICS AND RESINS
TABLE 7.3 POLYSTYRENE USES IN EXTRUSION GRADE APPLICATIONS
Application
Appliances/Consumer Electronics
Refrigerators & Freezers
Other
Furniture & Furnishings
Toys & Recreational
Housewares
Building & Construction
Miscellaneous Consumer & Industrial
Packaging & Disposables
Oriented Film & Sheet
Dairy Containers
Vending & Portion Cups
Lids
Plates & Bowls
Other Extrusion
Extrusion-Foam
Board
Sheet
Stock Food Trays
Egg Cartons
Single-Service Plates
Hinged Containers
Cups
Other Foam Sheet
TOTAL EXTRUSION APPLICATIONS
Consumption
(million Ibs)
1992
105
42
28
39
61
68
62
270
154
286
130
48
230
166
—
200
52
154
105
50
34
2,284
1993
109
43
29
41
63
71
62
285
158
293
136
52
234
170
—
204
50
160
108
51
35
2,354
Source:
Modern Plastics, January 1994
133
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
TABLE 7.4 POLYSTYRENE USES IN EXPANDABLE BEAD GRADE APPLICATIONS
Application
Billets
Building & Construction
Other
Shapes
Packaging
Other
Cups & Containers
Loose Fill
TOTAL EXPANDABLE BEAD APPLICATIONS
Consumption
(million Ibs)
1992
223
40
115
53
168
82
681
1993
219
40
114
53
167
82
675
Source:
Modern Plastics, January, 1994
TABLE 7.5 PRICE OF POLYSTYRENE
Polystyrene Grade
Crystalline
Molding
Expandable Bead (packaging)
Price
($/lb)
0.40 to 0.41
0.43 to 0.45
0.53 to 0.55
Source:
Chemical Marketing Reporter, February 7, 1994
PROCESSES FOR PRODUCING
POLYSTYRENE
To obtain styrene monomer, the building
block in the polymerization process to obtain
polystyrene, benzene and ethylbenzene are
required to be sequentially supplied or produced.
Chapter 2 presented benzene production
processes. The following sections discuss
ethylbenzene, styrene, and polystyrene
production processes.
Production of Ethylbenzene
Ethylbenzene is produced by the vapor phase
alkylation of benzene with ethylene in a fixed bed
reactor. In the process, fresh and recycled
benzene are preheated, vaporized, and combined
with a polyethylbenzene recycle stream and fresh
ethylene. The combined feedstock is fed to a
reactor that contains a proprietary, fixed,
heterogeneous catalyst. The vapor phase
alkylation of the benzene with the ethylene
occurs at moderate pressures. The effluent from
134
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CHAPTER?: PLASTICS AND RESINS
the reactor is sent to a benzene fractionation
system for separation and purification of the
ethylbenzene. Unreacted benzene is removed
from the first distillation column as an overhead
stream, and recycled to the reactor. The bottoms
stream is fractionated in a two column system.
In ihe first column, ethylbenzene is separated
from higher boiling components and becomes an
overhead stream. The bottoms from this column
are distilled; polyethylbenzene and other
alkylaromatics are recovered in an overhead
stream and recycled to the front end of the
reactor; the bottoms stream is used as ruel oil.
The process is very energy efficient and
produces almost no waste heat that cannot be
recovered as low or medium pressure steam.7
Production of Styrene Monomer
Polymer grade styrene monomer is produced
by the dehydrogenation of ethylbenzene. The
dehydrogenation reaction uses a commercially
available catalyst with a service life of about two
years and is carried out in the presence of steam
at high temperatures, under a vacuum.
Elfluent from the catalytic reactor is
condensed and stripped to remove residual
aromatics. A subsequent fractionation train
separates high purity styrene, unconverted
ethylbenzene, and reaction byproducts. Toluene,
another 33/50 organic chemical, is one of the
byproducts of the reaction. To prevent
premature polymerization of the styrene in the
fractionation system, a proprietary
polymerization inhibitor is added to the system.
Production of Polystyrene
Several processes are used commercially to
obtain raw polystyrene, depending on the grade
of polystyrene desired and the manufacturer. All
of the processes involve the polymerization of
the styrene monomer. Two processes performed
on a large scale are the bulk and pearl
polymerization modes.
Bulk Polymerization Mode. In the bulk
polymerization mode, the styrene monomer is
continuously polymerized in either the liquid or
the vapor state. The type of polystyrene desired
for the end-product dictates which reaction
conditions are used. Polystyrene resins of high
average molecular weight are produced at
moderate temperatures without a catalyst.
Increasing the temperature and using a catalyst
like benzoyl peroxide, oxygen, or stannic
chloride causes the average molecular weight of
the polystyrene and the solution viscosity to
decrease.
Styrene of 99.5 percent purity is typically
charged to a stainless steel kettle with other
reaction ingredients, heated to 80 to 85°C and
polymerized to 35 to 40 percent conversion. The
polymerization reaction occurs over 40 to 60
hours. The viscous product solution is then
passed down a tower with internal zones of
increasing temperature up to 200°C to strip
unreacted styrene monomer. The polystyrene is
removed in string-like form, cooled and crushed
into pellets for end-product manufacturing.8
Pearl Polymerization. Pearl polymerization
is a batch mode of producing polystyrene, used
to prepare special grades of polystyrene. Vessels
with 5 to 10 cubic meter (m3) volume are used
to produce spherical polystyrene pellets that are
0.5 mm or smaller in diameter. Addition of low
boiling hydrocarbons will yield polystyrene that
softens on heating and has very high insulating
capacity.9
Depending on the grade and formulation of
polystyrene required, styrene monomer, water,
reaction inhibitors, and suspending agents are
added to a batch reactor. The feed mixture is
then agitated and subjected to a time-temperature
profile. The reaction conditions force the
styrene monomer into suspended beads
surrounded by the aqueous reaction mixture.
Pentane is added to the reactor at a pre-
determined time to aid the expansion of the
beads. The polymerization reaction continues to
nearly 100 percent conversion. The polystyrene
beads are then cooled and processed further in a
continuous mode.10
135
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENVIRONMENTAL RELEASES FROM
PRODUCTION OF POLYSTYRENE
Environmental releases of the toxic chemicals
used in the chemical synthesis of polystyrene
occur from the production of these chemicals
through the styrene manufacturing process. The
following sections present the environmental
releases of benzene from the benzene production
process that can be associated with polystyrene
production, and the environmental releases of
benzene, ethylbenzene, styrene, and toluene
from the production of styrene and polystyrene.
Nearly 100,000 pounds of benzene releases
from petroleum refineries can be attributed to
styrene production. More than 67,000 pounds
of benzene and 2.6 million pounds of toluene
were reported released to the environment in
1991 by producers of plastics and resins.
Environmental Releases from Benzene
Production
Chapter 2 discussed the environmental
releases of benzene from petroleum refineries,
where more than 4.9 million pounds of benzene
were emitted to the environment. Figure 2.1
showed that about 3.3 percent of crude oil is
used as a petrochemical feedstock to produce
benzene and other chemical products, including
toluene and xylene. Based on the chemical-use
tree diagram in Figure 2.3, 53 percent of the
benzene feedstock is used to produce
ethylbenzene, of which 99 percent is used to
manufacture styrene monomer. Using these
percentages and a life cycle approach, it is
estimated that almost 100,000 pounds of the
releases and transfers of benzene from petroleum
refineries can be directly associated with
benzene's use as a chemical intermediate to
produce styrene.
Environmental Releases from Styrene
Production
Process air emissions of benzene,
ethylbenzene, styrene, and by-product toluene
along the polystyrene chemical synthesis pathway
can originate from the intermittent or continuous
purging of inert gases from reactor vessels,
drying beds, finishing columns, and other
process vessels. Fugitive air emissions can result
when process fluid leaks from plant equipment
such as pumps, compressors, and process valves.
Air emissions from storage and handling
operations also occur. Other sources of
environmental releases or transfers associated
with polystyrene production include:
• wastewater discharges directly from the plant
into rivers, streams or other bodies of water,
or transfers to a POTW;
• on-site release to landfills, surface
impoundments, land treatment, or another
mode of land disposal;
• disposal of wastes by deep-well injection; and
• transfers of wastes to off-site facilities for
treatment, storage, or disposal.
Manufacturers of plastics and resins are
classified under SIC 2821 and are required to
report their releases in TRI. Table 7.6 presents
the environmental releases and transfers of
benzene, ethylbenzene, styrene, and toluene that
were reported under SIC 2821 in the 1991 TRI.
This data are for all plastics and resins
manufacturers who reported their releases that
year and do not represent the releases just from
the production of styrene and styrene products.
The data do illustrate, however, the substantial
quantities of toxic chemicals that are released to
the environment to produce plastics and resins.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
The health, safety, and environmental issues
associated with the use of polystyrene are
complex. Benzene, ethylbenzene, toluene, and
styrene, the chemicals used or produced during
the polystyrene manufacturing process, are all
136
-------
CHAPTER?: PLASTICS AND RESINS
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
toxic chemicals with both acute and chronic
health effects. Polystyrene products create waste
disposal problems since they take up valuable
landfill space and do not degrade in the
environment. Chapter 2 presented the health,
safety, and environmental issues associated with
benzene and toluene. The following sections
discuss the health, safety, and environmental
issues associated with ethylbenzene and styrene
and the problems created by the use and disposal
of polystyrene.
Ethylbenzene and Styrene
Ethylbenzene may enter the body through
inhalation, ingestion, or absorption through the
skin. Occupational exposure to ethylbenzene
vapors in confined areas has caused collapse,
coma, and death. Acute exposure to
ethylbenzene by inhalation also causes eye and
upper respiratory irritation. Respiratory failure
may occur. Prolonged exposure to ethylbenzene
vapors may result in nervous system
hematological disorders. Ingestion of
ethylbenzene may cause transient liver injury.11
EPA has insufficient data to classify
ethylbenzene as to human carcinogenicitv (Class
D).12
Ethylbenzene released to surface water will
evaporate fairly rapidly into the atmosphere.
When released to soil, it will partially evaporate
to the atmosphere, but may also leach into
groundwater. Ethylbenzene is degraded in the
atmosphere by reaction with photochemically
produced hydroxyl radicals. The atmospheric
half-life for ethylbenzene ranges from one half
hour to two days,,13
Inhalation of styrene can cause headache,
fatigue, weakness, nausea, vomiting, CNS
depression, and a sensation of drunkenness.
Alterations in psychoneurological functioning
have been described from chronic exposure.
Styrene exposure irritates the eyes, the
respiratory and gastrointestinal tracts, and the
skin. Effects on the liver and the reproductive
system from exposure to styrene have been
reported. The International Agency for
Research on Cancer has classified styrene as
possibly carcinogenic to humans (Group 2B).14
Styrene released to soil will biodegrade, but
may also leach into groundwater. Volatilization
and biodegradation are the dominant transport
and transformation processes for styrene in
water. Much of the styrene released into the
aquatic and terrestrial environments will partition
into the atmosphere. Styrene vapor in the
atmosphere reacts rapidly with hydroxyl radicals
and ozone. Styrene has been found to be a very
active generator of photochemical smog.15
Polystyrene
The contribution of plastics like polystyrene to
the solid wastestream is an important issue with
which many communities are grappling.
Diminishing landfill space has prompted an
increase in plastics recycling since few plastic
materials biodegrade. Even with large-scale
recycling, the waste disposal problems associated
with the use of plastics are both immediate and
long term.
Current projections are for the increased use
of polystyrene in all major application markets
by 1995. The use of polystyrene and other
polymers in the packaging industry results in the
nearly immediate placement of the polymer
packaging into the municipal solid wastestream.
Plastics used in the building industry and other
industries that manufacture durable goods are not
disposed of for many years. Eventually these
polymer products will also require disposal,
however, and contribute to the plastics
wastestream.
Thus, the percentages of plastics in the solid
wastestream is increasing. It has been reported
that, in 1991, plastics accounted for four to seven
percent by weight (approximately 30 percent by
volume) of the solid wastestream.16 Projections
for the year 2000 are that plastics will account
for at least ten percent of the stream by weight.17
In an effort to dispel the polystyrene waste
disposal problem, eight polystyrene
manufacturers have formed a coalition called the
National Polystyrene Recycling Company
138
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CHAPTER?: PLASTICS AND RESINS
(NPRC). The company's stated goal is to
establish a national recycling program and
infrastructure for post-consumer polystyrene
products. The NPRC is building five regional
polystyrene recycling centers in the U.S. The
company claims that through the joint efforts of
its members, the technology has been developed
to recycle polystyrene on a broad scale. The
goal of the company is to see 250 million pounds
of polystyrene products recycled annually by
1995. This translates to a 25 percent recycling
rate of polystyrene used in food service and
beverage packaging.18
The types of polystyrene that are slated for
recycling include: food trays, hamburger
containers, foam cups, protective packaging,
single use plates and bowls, meat trays, egg
cartons, clear salad containers, and cutlery.
Plans are to use the recycled polystyrene to
manufacture durable products with a long life
span, and not for food service products.
In 1991, the NPRC stated that 20 million
pounds of polystyrene were being recycled per
year and that each of its recycling centers could
handle 13 million pounds per year. The cost for
recycled polystyrene pellets in January, 1991 was
about $0.26 to $0.40 per pound.19
Critics of the NPRC plan point out that even
if the NPRC reaches its goal, 75 percent of
polystyrene used in food service and beverage
packaging and all polystyrene used in other
applications will still be discarded. Since
polystyrene is a very lightweight material,
transporting it to recycling centers may prove to
be too costly. Efforts to reduce packaging size,
and the widespread use of plastics recycling, may
prevent the volume percentage of plastics in the
solid wastestream from rapidly increasing.
While these efforts are laudable, they do not
provide an immediate or complete solution to the
plastics waste disposal problem, particularly for
products designed to be used once and then
thrown away.
Another area of concern with polystyrene
products is the use of CFCs and HCFCs as
blowing agents to manufacture foam products.
The Montreal Protocol and the Clean Air Act
Amendments of 1990 ban most remaining uses of
CFCs and HCFCs as foam blowing agents by
1996.
EVALUATION OF SUBSTITUTES
Safe substitute approaches to reducing the use
of the 33/50 chemicals benzene and toluene
through the reduced use of polystyrene include:
• eliminating the use of unnecessary packaging;
• reducing the use of disposable products; and
• substituting degradable polymers for
polystyrene.
Eliminating unnecessary packaging and using
reusable durable products are conservation
choices that do not require development of new
technologies. These safe substitute practices are
seeing increased use with increased
environmental awareness. The use of
unnecessary packaging is already being reduced
in some applications, partly because of consumer
pressure to market more environmentally
friendly products. The use of disposable
products can be reduced, particularly in ihe food
industry, by returning to the use of reusable,
durable products. Dishes made of glass or
reusable dinnerware can, obviously, replace
throwaway eating utensils in many applications.
Reusable products have some environmental
disadvantages, however, like the large amount of
energy required to manufacture glass, or to clean
products for reuse. Life cycle assessments of
plastic versus glass products are being conducted
to assess the relative environmental impacts of
these materials.
The use of paper products as an alternative to
petroleum-based plastic products can also reduce
the releases of the 33/50 chemicals. Life cycle
assessments of paper versus plastic products are
also being conducted.
Degradable plastics, however, are new
technological developments for polystyrene
139
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
substitution. They are developed primarily in
response to increasing environmental and
regulatory pressures. The following sections
assess degradable plastics as potential safe
substitutes for the polystyrene used in packaging
and disposables.
Degradable Plastics Industry
Early in the industrial revolution, virtually all
industrial inputs were based on plant and animal
products. Paints, varnishes, linoleum, soaps,
solvents, and plastics had their origin from plant
products, animal products, and/or byproducts of
these materials (e.g., methanol). In the last half
of the 19th century, several plant-product derived
plastics were developed, celluloid being a good
example. By the early 1900s, moldable plastics
from plants were being used in the manufacture
of cars and other consumer goods. In the 1920s
and 30s, however, much of the nation's research
funding focused on developing plastics and other
products from fossil fuels (coal, petroleum, and
their derivatives). By the end of World War II,
petroleum-based plastics, led by polyvinyl
chloride, dominated the plastics market.20 Faced
with limited worldwide reserves of fossil fuels
and other environmental concerns in the early
1980s, the focus began to shift again back
towards plant- and animal-based plastic products.
Five main categories of degradable plastics
have evolved from this new focus:
photodegradable plastics, starch-loaded
thermoplastics, starch-based plastics, sugar-based
plastic; and degradable, petroleum-based
polymers. The first two categories;
photodegradable plastics and starch-loaded
thermoplastics, were developed in the 1980s as a
solution to the solid waste problem. However,
limitations of these technologies resulted in less-
than-desirable solutions.
Photodegradable and Starch-Loaded
Polymers. Photodegradable plastics are
conventional petroleum-based plastics which
contain either carbonyl functional groups or
photodegradable additives. These functional
groups/additives, when exposed to ultraviolet
light, breakdown, thus degrading the plastic.
This technology has been used for years in
beverage can rings and waste disposal bags.
However, inadequate exposure to ultraviolet light
limits the degradability of these plastics within a
landfill environment. Starch-loaded
thermoplastics use the addition of a degradable
filler such as starch to a petroleum-based
polymer network. When these products degrade
(e.g., dissolution of the starch filler) the polymer
network is left behind as small pieces of plastic.21
Both materials incorporate petroleum-based
polymer and do not represent safe substitutes for
polystyrene or other petroleum-based plastics
within the context of this report.
Degradable, Petroleum-Based Polymers.
Degradable, petroleum-based polymers are a
new generation of degradable polymers which
overcome the limitations of photodegradable and
starch-loaded plastics. These products include
polycaprolactone (Union Carbide), polyester
(Planet Polymer Technologies), and polyvinyl
alcohol (Air Products and Chemicals) plastics.22
Though these materials are fully degradable and
offer a potential solution to the solid waste
problem, they are still derived from petroleum-
based chemicals. Thus, for this report, the
degradable, petroleum-based polymers do not
represent safe substitutes for polystyrene, and
will not be discussed further.
Starch-based and sugar-based plastics
eliminate the use of benzene and other
petrochemicals during their manufacturing
processes. Processing characteristics and
material properties of these safe substitutes are
compatible with many polystyrene products,
allowing direct substitution.
Overview of Starch-Based and Sugar-
Based Plastics. The other two categories of
polymers, starch-based plastics and sugar-based
plastics, also represent the new generation of
plastics, but are derived partially or fully from
nonpetroleum-based materials. Table 7.7 lists
the U.S. producers of these degradable plastics
in 1992, their production capacity, and the price
of the different plastics. These companies claim
140
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CHAPTER?: PLASTICS AND RESINS
easy processing of their resins in conventional
equipment, properties comparable to existing
commodity resins, and degradation in soil or
water.22 Base-materials for degradable polymers
include starch-based polymers and
thermoplastics, polyactic acid and polyactides.
Molding, extrusion, and film grade degradable
polymers are offered. Manufacturers cite
applicability of the degradable polymers to
packaging and coatings, mulch bags and other
films, and drug delivery systems.
The current focus of the degradable plastics
industry is on packaging, specifically plastic
bottles, film packaging, and the packaging used
in quick service restaurants. In 1993, packaging
represented nearly 30 percent of the entire
plastics industry, or nearly 18 billion pounds;
polystyrene and polyethylene accounted for about
62 percent of this plastic packaging total.
Estimates of present and future market shares of
degradable plastics vary. One source states in
1992 degradable polymers comprised 1.8 percent
of the total plastics production in the U.S.; in
1993 the percentage had increased to 2.1. This
same source estimates by 1996 the degradable
plastics share is expected to be more than four
percent. Another source states 0.8 percent (or 5
million pounds) of the plastics market is
degradable, with a future market of 1.2 billion
pounds by 2002. A third source estimates the
current global markets for degradable polymers
range up to three billion pounds per year.23
TABLE 7.7 PRODUCERS OF DEGRADABLE POLYMERS
Producer
Cargill
EcoChem
Ecostar
ICI (now Zeneca)
American Excelsior
Novamont
Novon
UniStar
Polymer
polylactic acid resins
polylactide resins
starch master batch w/ PE
copolymer
polyhydroxybutyrate
valerate copolymers
Eco-foam (starch)
starch w/ copolymer
starch
starch graft copolymer
Capacity
(million pounds)
10
(250 by 1996)
20
(100 by 1995)
10
. 1.2
(20 by 1996)
N/A
50
100
10
(100 bv 1996)
Resin Price
$/lb
1.00 to 3.00
1.50 to 2.00
1.30 to 1.60
8.50
1.30/ft3
1.60 to 2.50
1.50-3.00
0.75-1.25
Sources:
"Biodegradables Blossom Into Field of Dreams for Packagers," Plastics World, March 1993, p. 22
"Truly Degradable' Resins Are Now Truly Commercial," Modern Plastics, February 1992, p. 62-64
"Bio-Plastics Start to Mature," Chemical Marketing Reporter, April 26, 1993, p. 7
"Cargill Moves on Plan to Make Lactic Polymers," Chemical Marketing Reporter, May 24, 1993, p. 7
"Now You See It...," Chemical Marketing Reporter, July 6, 1992
N/A: Not Available
141
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PART U: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Standard Setting for Degradable Plastics.
The American Society of Testing & Materials'
(ASTM) subcommittee on degradable plastics
and the advisory committee of the degradable
polymer project of ASTM's Institute for
Standards Research are developing standard
definitions, classifications, and test procedures
for degradables. The ASTM standards are
intended to provide the basis for substantiating
disposability claims for degradable polymers in
full-scale disposal systems. Sugar-based
degradable polymers will be tested on a number
of solid waste disposal systems, the first of which
will be composting.24 In the spring of 1993
standard-setting groups from the U.S., Japan,
Germany, and industrial representatives reached
a unanimous consensus that biodegradable
materials must be completely consumed by
microorganisms in a composting process,
producing only natural by-products like carbon
dioxide, methane, water, and biomass.25
Other effects are underway to set standards
for degradable plastics and polymers. In April,
1993, the U.S. EPA issued the "Proposed
Degradability Standards for Plastic Ring Holders
for Bottles, Cans" (58 FR 18062). In this
proposal, the EPA sets a guideline for plastic
ring holders to disintegrate within 35 days of
placement in a marine environment. The State
of Florida mandates that materials labeled as
biodegradable do so within 120 days of
placement in a landfill.26
Starch-Based Degradable Plastics
Starch-based degradable polymers offer two
main environmental advantages compared to
polystyrene: 1) the use of 33/50 chemicals is
either reduced or eliminated; and 2) the plastics
do not pose a solid waste disposal problem if
managed correctly. Starch-based plastics blend
starches (traditionally corn starch) with
plasticizers and additives to produce a material
that possesses desired plastic properties and can
be thermoprocessed using conventional plastic
processes equipment. Plasticizers are formulated
from various natural and synthetic oils.
Additives include natural and synthetic
compounds, mineral and organometallic salts.
Some plasticizers and additives used in
degradable plastics are readily degradable
themselves and therefore pose limited
environmental risk after decomposition.27
However, the U.S. EPA is aware that a number
of additives, in their pure, concentrated form,
are toxic.28
Figure 7.129 is a schematic of the data in
Table 7.7, showing base materials of some of the
degradable polymers that are currently available.
As can be seen, companies producing starch-
based polymers use a variety of materials, some
of which are petroleum-based. The petroleum-
based polymers used by Novamont, Ecostar, and
UniStar, though degradable, still represent
polymers that use 33/50 chemicals and are not
safe substitutes for polystyrene in the context of
this report. Therefore, further evaluation of
these products will not be performed. Novon
and American Excelsior, however, are two
manufacturers of plastic substitutes that
completely eliminate or greatly minimize the use
of petroleum-based raw materials. Therefore,
this report focuses only on standard plastics made
by these manufacturers as examples of safe
substitutes for polystyrene.
Novon Degradable Polymers. The Novon
Product Group, manufactured by the Warner-
Lambert Company of Morris Plains, New
Jersey, is derived from the renewable resource
of starch from corn and potatoes. The company
claims the polymers have the moldability and
performance characteristics of traditional plastics
with the decomposition benefits of organic
materials like paper. It also claims that all
grades of Novon polymers are completely
degradable in biologically active environments,
like waste treatment plants, and in soil and
water. Exposure to water and naturally
occurring biologically active environments break
down the polymer to water, carbon dioxide, and
naturally occurring minerals that are added
during the polymer synthesis. The mineral
additives are used to vary the properties of the
resin. The polymers can be pigmented and
molded like traditional plastics and have similar
strength and appearance.30
142
-------
CHAPTER?: PLASTICS AND RESINS
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143
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PART O: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
The Novon polymers were first invented in
the 1980s by Warner-Lambert for
pharmaceutical capsuling applications. The
company has 20 experimental grades of Novon
polymers in development and started up a 100
million pound per year plant in early 1992 in
Rockford, Illinois to produce seven grades of
Novon. The Novon 2020 foam grade is intended
to replace loose-fill polystyrene peanuts. Novon
3001 grade is an injection molding grade used in
applications where quick biodegradation is
required. In August of 1993, Novon introduced
three new degradable polymers: M4900, an
extrudable grade polymer for blown and cast
film applications; M5600, a general purpose,
injection blow molding; and Ml801, a general
purpose, injection molding plastic. Possible
applications of these plastics include products
such as bags (M4900), bottles (M5600), and
cutlery and medical products (Ml801).31
A Cincinnati firm, Storopack, Inc., produces
Renature, a product in which the water
degradable Novon 2020 is formed into a hollow
double tube shape using water as the blowing
agent. Storopack claims the performance of
Renature is comparable to the polystyrene
peanuts used as a packaging agent. After use,
the Renature peanuts can be dissolved with
water.
Late in 1993 the Warner-Lambert Company
announced it would suspend the operations of this
Novon Products Group and liquidate its hard
assets. Reasons for this announcement included
the slow development of the degradable polymers
markets and the infrastructure that can handle
them, and Warner-Lambert's desire to refocus
on the companies core business,
Pharmaceuticals. No buyer has yet been found.32
American Excelsior. The American
Excelsior Company of Arlington, Texas also
manufactures biodegradable loose-fill peanuts as
a safe substitute for polystyrene foam. American
Excelsior's product is known as Eco-foam. Eco-
foam was developed and patented by National
Starch and Chemical Corporation in November,
1990. The company claims that Eco-foam looks,
dispenses, and cushions much like expandable
polystyrene. When saturated with water,
however, it quickly breaks down into harmless
carbon dioxide.
Eco-foam, like the Novon polymer class, is a
starch-based material that contains 95 percent
corn starch. Unlike the Novon materials, Eco-
foam contains a small amount of water soluble
synthetic additive (polyvinyl alcohol) which it
plans to eliminate from its products in the near
future. The product complies with FDA
regulations for contact with food but is not a food
product. The product is designed to decompose
when saturated with water. At exposure to high
humidity and high temperatures, the product will
shrink but will not become sticky or cling to the
package content, thus retaining its packaging
properties to a significant extent.33
In 1990 Eastman Kodak Company evaluated
the use of Eco-foam for packaging a wide variety
of products at a Kodak shipping plant in
suburban Chicago. Kodak reported that Eco-
foam handles and protects very much like
expanded polystyrene foam. Kodak found that
Eco-foam does not decompose when exposed to
normal plant humidity levels and offers the same
flowability and cushioning ability as expandable
polystyrene. Since that time Kodak, Sony, and
Canon, among others, have switched to Eco-
foam as a drop-in replacement for polystyrene
peanuts.34 In 1990 starch-based loosefill
packaging didn't exist; now it constitutes ten
percent of a 55 million pound annual market.35
The major drawback to Eco-foam is its cost,
about one-and-a-half to two-times the price per
pound of traditional loose-fill materials. Cost is
expected to decrease as capacity and demand for
the product increases. American Excelsior is
investing $400,000 in equipment at six U.S.
plants to expand production nationally.
Sugar-Based Degradable Polymers
Two naturally degradable polymers, derived
from the fermentation products of starches and
sugars, are also potential substitutes for
polystyrene and other petroleum-based polymers
(Figure 7.1 again). One naturally degradable
polymer, marketed by Zeneca (formerly ICI), is
poly(hydroxybutyrate valerate) (PHBV). This
polymer is produced by the fermentation of plant
144
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CHAPTER?: PLASTICS AND RESINS
sugars (glucose) and simple organic acids.
Varying the amount of organic acid in the
fermentation process varies the valeric content of
the polymer, thus controlling the physical
properties of the product; the more valeric
content of the polymer, the more flexible and
ductible the final product is. PHBV is more
moisture resistant than starch-based products,
and also resists oils and greases. PHBV's lower
melting temperature and viscosity will require
setting changes in the processing equipment
currently used with polyethylene (the plastic
PHBV is suited to replace). This material is
already commercialized in Europe under the
trade name Biopol, and is used in shampoo
bottles, disposable razors, and writing pens.36
Another naturally degradable polymer is
poly lactic acid (PLA). PLA is also derived from
the fermentation process of starch-based
materials which produces "natural" lactic acid
synthetic (lactic acid can also be manufactured
from petrochemcials, hence the "natural"
notation). Lactic acid is then fed into a
proprietary polymerization process to produce
PLA. Currently, the major manufacturers of
lactic acid/PLA are Cargill and EcoChem.
Cargill's $8,000,000, ten million pound per year
lactic acid/PLA facility in Savage, Minnesota
became operational in February, 1994. Officials
of Cargill predict that by 1996 market demands
will require a larger facility with a capacity of
250 million pounds per year. The source of
starch for Cargill is corn processing by-products.
EcoChem1 s Adell, Wisconsin facility (20 million
pounds per year capacity) began operations in
1992. They have plans to expand this facility to
produce 100 pounds per year of PLA by 1995.
Cheese whey is EcoChem's starch source.38
PLA is clear and not readily soluble in water.
Although not as well established in the
commercial market as PHBV, expected
applications include disposable food containers,
cutlery, diapers, personal hygiene products,
medical garments, yard bags, and agricultural
applications.39
Management of Degradable Polymers
Two of the driving forces behind the
development of degradable polymers were the
issues of solid waste and the increasingly scarce
space available in landfills. It was estimated that
packaging waste accounted for nearly 30 percent
by volume of the municipal solid wastestrearn in
1991 .^ Degradable polymers were initially
marketed as a solution to these issues. Modern
landfills, however, are not designed and
managed to allow degradation, even of readily
degradable materials; they are designed to
minimize moisture and heat to control methane
gas build-up and minimize the potential for
groundwater contamination.41
Current manufacturers of starch-based and
inherently degradable polymers realize this
limitation of landfills; even degradable plastics
constitute a landfill disposal problem. The
new degradable plastics producers, therefore,
de-emphasize the need to fit into traditional
disposal methods (i.e., landfills and
incineration). They support the further
development of a compost infrastructure to
properly manage their products. Composting
optimizes the environmental conditions
(biological activity, heat, and moisture) needed
to facilitate degradation of materials to C02,
water, and mineral-rich soils. When properly
disposed of in compost facilities, starch-based,
PHBV, and PLA plastics reportedly decompose
within 60 to 120 days.42
To date, there are 19 mixed municipal solid
waste composting facilities in the U.S., with 7.5
million pounds per day processing capabilities.
Nine more facilities are under construction and
33 others are in various stages of planning.
Even with these existing and planned facilities,
the infrastructure to properly manage the 40
percent of municipal solid waste which is
compostable (including degradable plastics) is not
adequate.43 Without such an infrastructure, the
extent to which degradable polymers can enter
the market may be limited.
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PART D; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Research is also needed on the mechanisms of
degradation and the environmental characteristics
of degradable plastics and their degradation
by-products in a compost environment. To
address these issues a new industrial research
consortium was formed in February, 1993.
Cargill, Novon, EcoChem, Minnesota Corn
Growers, Philip Environmental, a Canadian
resource recovery firm, and Michigan State
University, with funding from the U.S.
Department of Agriculture, have begun a two-
year compost demonstration project. The project
will look at the biological and chemical activities
that degrade the variety of materials that enter a
composting facility, and the toxic/environmental
characteristics of the byproducts.44
Finally, research is needed to investigate the
environmental impacts of other options for
managing discarded degradable polymers. For
example, many of the starch-based plastics will
quickly dissolve in water. Assuming the proper
industrial discharge permits have been obtained,
industrial users of degradable polymers could
dissolve them in water and discharge the effluent
to a local POTW. Similarly, individuals who
purchase products packed in starch-based, loose-
fill "peanuts" could dissolve the packaging and
discharge it to the local sewer system. With a
large-scale switch to degradable polymers,
however, research is needed to determine the
effects of the resulting increase in biological
oxygen demand on local POTW capacity.
Conclusions
The use of polystyrene can be reduced
through the use of substitutes, reducing the
use and releases of benzene and other 33/50
chemicals and helping alleviate the nation's
solid waste disposal problems. Conservation
choices like eliminating unnecessary packaging
and using reusable products or using safe
substitutes like degradable polymers are
practical, viable ways to reduce the use of
polystyrene. Already, polystyrene use-reduction
is occurring as environmentally conscious
consumers encourage manufacturers to use less
packaging or environmentally sound materials.
These safe substitute approaches help diminish
the amount of plastics in the nation's solid
wastestream and reduce the nation's hazardous
waste burden by reducing the use of toxic
chemicals. Further information is needed,
however, on synthetic additives used in some
degradable polymers to verify that these additives
do not cause adverse human health or
environmental effects.
146
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CHAPTER?: PLASTICS AND RESINS
ENDNOTES
1 "Resins 1992: Supply Patterns are Changing," Modern Plastics, January 1992, p. 85.
2 "Resins 1994: Plotting a Course for Supply," Modern Plastics, January 1994, p. 45.
3 Ibid.
4 "Resins 1992: Supply Patterns are Changing," Modern Plastics, January 1992, p. 85.
5 "Resins 1994: Plotting a Course for Supply," Modern Plastics, January 1994, p. 45.
6 "Resins 1992: Supply Patterns are Changing," Modern Plastics, January 1992, p. 85.
7 "Petrochemical Handbook '91," Hydrocarbon Processing, March 1991, p. 154.
8 Ibid., p. 176.
9 F:A. Henglein, Chemical Technology, (New York: Pergamon Press, 1969), p. 746.
10 "Petrochemical Handbook '91," Hydrocarbon Processing, March 1991, p. 154.
11 "Ethyl Benzene," Hazardous Substances Data Bank, May 29, 1992.
12 "Ethyl Benzene," Integrated Risk Information System, 1994.
13 "Ethyl Benzene," Hazardous Substances Data Bank, May 29, 1992.
14 "Styrene," Hazardous Substances Data Bank, May 29, 1992.
15 Ibid.
16 Karen Augustine, "Packaging and the Environment: How You Can Make a Difference,"
Modern Materials Handling, 1992.
Christopher Rivard, Ph.D., "Biodegradable Plastics, Further Research Needed to Meet
Environmental Mandate," Journal of Environmental Health, Vol. 53, No. 4, January/February 1991.
17 Nancy Wolf and Ellen Feldman, Plastics - American's Packaging Dilemma, Environmental
Action Coalition, (Washington, DC: Island Press, 1991).
18 The NPRC Goal, National Polystyrene Recycling Company.
19 The Blueprint for Plastics Recycling, The Council for Solid Waste Solutions, p. 29.
20 "Industrial Uses of Agricultural Materials, Situation, and Outlook Report," US Department of
Agriculture, Economic Research Service, June 1993.
21 "Biodegradables, Friend or Foe?," ECN Environmental Protection Review, July/August 1990.
22 "Biodegradables Blossom Into Field of Dreams for Packagers," Plastics World, March 1993.
147
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PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
23 Karen F. Lindsay, "Truly Degradable Resins are Now Truly Commercial," Modern Plastics
February 1992, p. 62.
24 "Bio-Plastics Start to Mature," Chemical Marketing Reporter, April 26, 1993.
"Biodegradable Polymers Forge Ahead," BioCycle, September, 1993.
"The Effects of Expanding Biodegradable Polymer Production on the Farm Sector," US Dept of
Agriculture, Economic Research Service, June 1993.
"Truly Degradable Resins Are Now Truly Commercial," Modern Plastics, February 1992.
25 ..
26
Truly Degradable Resins Are Now Truly Commercial," Modern Plastics, February 1992.
"Biodegradable Polymers Forge Ahead," BioCycle, September 1993, p. 72-74.
27 HI
'Degradability Standards Proposed by EPA for Plastic Six-Pack Rings for Bottles, Cans "
Environmental Reporter, The Bureau of National Affairs, Inc., Vol. 23, No. 50, April 9, 1993.
"Bio-Plastics Start to Mature," Chemical Marketing Reporter, April 26, 1993.
28 Christopher Rivard, Ph.D., "Biodegradable Plastics, Further Research Needed to Meet
Environmental Mandate," Journal of Environmental Health, Vol. 53, No. 4, January/February 1991
"Biodegradable, Friends or Foe?," ECNEnvironmental Protection Review, July/August 1990.
29 "Degradability Standards Proposed by EPA for Plastic Six-Pacl* Rings for Bottles Cans "
Environmental Reporter, The Bureau of National Affairs, Inc., Vol. 23, No. 50, April 9, 1993.
30 Sources for Figure 7.1:
"Biodegradables Blossom Into Field of Dreams for Packagers," Plastics World, March 1993.
" Loose-Fill an Environmentalist Can Love," Packaging Digest, April 1991
I'Degradable Plastics Unveiled," Chemical Marketing Reporter, August 16, 1993.
"Novon Serves Up a New Course of Biodegradable Polymers," Chemical Week, August 18 1993
^'Now you See It...," Chemical Marketing Reporter, July 6, 1992.
"Cargill Moves on Plan to Make Lactic Polymers," Chemical Marketing Reporter, May 24, 1993.
31 Don Loepp, "Novon Debuts Two Degradable Resins, Begins Building Plant " Plastic News
June 18, 1991.
33 »
Degradable Plastics Unveiled," Chemical Marketing Reporter, August 16, 1993.
Novon Drops from Biopolymers," Chemical Marketing Reporter, November 22, 1993.
34 "Loose-Fill an Environmentalist Can Love," Packaging Digest, April 1991, p. 44.
35 "Now You See It...," Chemical Marketing Reporter, July 6, 1992.
* "Novon Drops from Biopolymers," Chemical Marketing Reporter, November 22, 1993.
"Now You See It...," Chemical Marketing Reporter, July 6, 1992.
37 "Biodegradables Blossom into Field of Dreams for Packagers," Plastics World, March 1993
"Biodegradable Polymers Forge Ahead," BioCycle, September 1993.
"Gone with the Wind, Rain, Sun, Bacteria," Chemical Business, May 1990.
148
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CHAPTER?: PLASTICS AND RESINS
"Biodegradables, Friend or Foe?," ECN Environmental Protection Review, July /August, 1990.
"Cargill Moves on Plan to Make Lactic Polymers," Chemical Marketing Reporter, May 24,
38
1993.
39 "Biodegradables Blossom into Field of Dreams for Packagers," Plastics World, March 1993.
"Now You See It...," Chemical Marketing Reporter, July 6, 1992.
"Cargill Moves on Plan to Make Lactic Polymers," Chemical Marketing Reporter, May 24, 1.993.
40 "Packaging and the Environment: How You Can Make a Difference," Modern Materials Handling,
October 1992.
41 "Novon Drops From Biopolymers," Chemical Marketing Reporter, November 22, 1993.
42 "Degradable Polymers Forge Ahead," BioCycle, September 1993.
"Bio-Plastics Start to Mature," Chemical Marketing Reporter, April 26, 1993.
43 ii.
'Truly Degradable Resins are Now Truly Commercial," Modern Plastics, February 1992.
44 Ibid.
149
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-------
CHAPTERS
PAINTS AND COATINGS
The product class of paints and coatings
includes paints, varnishes, lacquers, and other
materials that form a solid, cohesive, and well-
adhering film when spread over a surface in a
thin layer. Paints and coatings are used to
decorate and protect a substrate like metal,
wood, or plastic from air, microorganisms,
water, and chemicals. They may also provide
improved mechanical properties like better
hardness and abrasion resistance. The
consistency and film properties of a paint or
coating are usually developed for a limited field
of application and a particular coating process.
Traditionally, paints and coatings have been
solvent-borne liquids using 33/50 chemicals
(toluene, xylene, MEK, and MIBK) as solvents
or diluents. With increased concern over the
health and environmental effects of solvent
releases, however, safe substitutes for solvent-
borne coatings are seeing increased use. This
chapter describes the use of and safe substitutes
for 33/50 organic solvents in paints and coatings.
INDUSTRY PROFILE
The paints and coatings industry consists of
two sectors: trade sales or shelf goods and
chemical coatings or industrial product finishes.
Trade sales or shelf goods include architectural
paints sold to consumers, contractors, or
professional painters for use on new construction
or for maintenance. They are usually air-dry
finishes which do not require baking or some
other physical process after application.
Chemical coatings or industrial-product
finishes are used in factory applications to coat
consumer products such as automobiles and
appliances. These finishes are produced to
manufacturers' specifications and are usually
applied on a production line and then baked.
These paints are traditionally applied by spray,
dip, roller, or electrodeposition.
The 33/50 chemicals toluene, xylene, MEK,
and MIBK are widely used as solvents or
diluents in solvent-borne paints and coatings.
With increased concern about the health and
environmental effects of solvent releases,
however, safe substitutes for solvent-borne
coatings are gaining in market share.
The industrial paints and coatings market in
the U.S. in 1990 was about $7.2 billion, while
the trade sales market was approximately $4.6
billion. Although not the largest market segment
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
in terms of expenditures, the trade sales sector is
the largest segment of the paints and coatings
market in terms of volume.1
Paints and coatings can be classified
according to their use (e.g., automotive, marine,
architectural), application method (e.g., spray,
dip), processing state (e.g., water-based, solvent-
borne), drying behavior (e.g., cold curing, air-
dried, heat-cured), or chemical nature of the
binder (e.g., alkyd resin, epoxy resin). Usually,
more than one of these parameters is required to
specifically define and characterize a coating
system. One of the more common
classifications, however, is based on binder
chemistry, which is indicative of the working
properties of the coating material and
performance of the film. Paints and coatings
classified according to the types of resins or
binders present include oil-based coatings,
cellulose-based coatings, vinyl coatings, acrylic
coatings, alkyd coatings, saturated or unsaturated
polyester coatings, polyurethane coatings, epoxy
coatings, and asphalt, bitumen, and pitch
coatings. Some resins in a class may be soluble
in organic solvents, while other resins in the
same class are soluble in water or are water
dispersible.2 Toluene, xylene, MEK, and MIBK
are used as solvents or diluents for a number of
the different resins used as binders.
Quantity of 33/50 Organic Solvents used in
Paints and Coatings
Table 8.1 presents the quantity of 33/50
organic solvents used in paint and coating
formulations between 1979 and 1989. The total
consumption of all of the major solvents used in
paints and coatings during this period is also
shown for reference.
Increasingly stringent environmental
regulations have caused industry to decrease the
concentration of solvents in paints and coatings.
The production of conventional solvent-based
coatings has dropped from about 100 million dry
gallons in 1983 to about 65 million dry gallons in
1987. On the other hand, production of high-
solids (i.e., lower solvent concentration) solvent-
based paints increased from 18 million dry
gallons in 1983 to 35 million dry gallons in
1993.3
The trend toward decreased production of
conventional solvent-based paints does not agree
with the solvent consumption data in Table 8.1.
These data show that overall solvent use in paints
and coatings has actually experienced a steady,
though small, increase since 1982. No
explanation was found in this study for the
increase in consumption of solvents in paints
during a period when solvent-borne paint
consumption was declining.
Price of 33/50 Organic Solvents in Paints and
Coatings
Table 2.5 in Chapter 2 listed the prices of the
33/50 organic solvents that are used in paints and
coatings. Prices range from $0.67 per pound for
toluene to $0.23 per pound for o-xylene. The
price of the 33/50 aromatic organic solvents are
dependent on the price of crude oil and market
demands for other petroleum products.
Traditional solvent-based paints contain 50 to
70 percent solvents. Although the solvent is the
single largest component of a solvent-based paint
or coating formulation, it contributes a smaller
fraction of the cost.
COMPONENTS OF PAINTS AND
COATINGS
The three major components of solvent-borne
paints are pigments, binders, and solvents or
thinners. A number of additives, such as driers,
anti-skinning and anti-settling agents, and
fungicides or bactericides, are also used.
Pigments
Pigments and extender pigments offer paints
and coatings their color and hiding power, as
well as increased resistance against corrosion and
wear in certain cases. Pigments consist of metal,
inorganic, organic, and organometallic
compounds dispersed in the paint and film.4 The
type of pigment determines the color and color
stability of the paint or coating, while the amount
152
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CHAPTERS: PAINTS AND COATINGS
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153
-------
PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
of pigment determines the gloss, hiding power,
and permeability of the coating. The degree to
which the pigment is dispersed in the binder, and
the volume of film occupied by the pigment also
influence the film properties. A gloss paint
contains enough binder so that all pigment
particles are completely encased, giving a
smooth glossy surface. In a flat paint, particles
of the pigment which are not covered by the
binder protrude at the surface, breaking up
reflected light and producing a dull surface.
Binders
Binders of paints and coatings, which include
film-forming substances and plasticizers,
constitute the continuous phase in paint films and
contribute to the films protective and general
mechanical properties. Important properties of
the film include flexibility, durability, and
chemical resistance. Film-forming binders can
be either macromolecular products (large,
intricate molecular structures) or low-molecular-
mass polymers that react to form
macromolecules on curing. Macromolecules
include cellulose nitrate and vinyl chloride
copolymers; low-molecular-mass polymers
include polyurethanes and epoxy resins. Most
film-forming binders are resins (e.g., alkyl
resins, epoxy resins). Resins are readily soluble
in either organic solvents or water, but not both.
They increase film hardness and reduce the
drying time in oxidative curing systems.
Plasticizers, also identified as binders, are most
often organic liquids of low volatility (e.g.,
esters of poly acids). They have the opposite
effect to resins on the final coating; they improve
the flexibility of the formed film. Binders are
usually organic materials, but a few inorganic
binders are used.
Solvents
Solvents or thinners are usually volatile
organic liquids. They dissolve binder
components and provide a means of adjusting the
viscosity of the solution for processing
consistency. Solvents also improve the wetting
capabilities of the solution, dispersion of the
pigments, and leveling and gloss of the film.5
Following application, the vast majority of the
solvent is lost during the film formation process
and does not influence the performance of the
dry film. Solvents are also used as diluents to
reduce the cost and assist in the solution of other
ingredients.
Toluene is the most extensively used diluent
for cellulose nitrate lacquers. It will also
dissolve a large number of resins, but is not a
solvent for PVC, copals, or shellac. Toluene is
miscible with drying oils like linseed oil or tung
oil used in oil-based paints and with most other
solvents.6
Xylene has high solvent power for a wide
range of resins and a high rate of evaporation.
As a result, xylene is widely used in both stoving
(heat-cured) and rapid air-drying coatings. Like
toluene, xylene is used as a diluent for cellulose
nitrate lacquers. It is the main solvent for
lacquers made with polystyrene,
poiymethlymethacrylate, and chlorinated rubber
binders. Xylene is also an excellent solvent for
asphaltic bitumen and petroleum pitch.7
MEK and MIBK are solvents for a wide range
of resins. MIBK is extensively used in both
stoving enamels and lacquers.8
Until the early 1980s, paints usually contained
50 to 70 percent solvents by volume. Since then,
high-solids paints and water-borne systems have
replaced many traditional coating materials in
industry, handicrafts, and households. Still,
except for powder coatings and a few other
solvent-free paints, organic solvents are used in
all paints, even those that are water-borne.9
DESIRED PROPERTIES OF PAINT AND
COATING SOLVENTS
Solvents are used in paints and coatings to
reduce the viscosity of the material and thus
facilitate the application of a uniform coating.
Solvents are also used to disperse pigments and
extenders. Solvents used in a particular paint or
coating must be suitable for the oil or resin
present. The important properties of paint
solvents are: 1) solvent power; 2) rate of
evaporation; 3) boiling point and distillation
154
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CHAPTERS: PAINTS AND COATINGS
range; 4) flash point and inflammability; and 5)
toxicity.10 A solvent is typically selected based
on its ability to dissolve a resin and its
evaporation rate.11 Solvent combinations are
often used in paint formulations. Therefore, the
changes in the solvency of the resins as the
different solvent components evaporate must also
be considered.
Classes of materials used as organic solvents
include aliphatic hydrocarbons, aromatic
hydrocarbons (toluene, xylene, and the trimethyl
benzenes), ketones (MEK, MIBK), alcohols,
esters, and glycols esters.
COATING PROCESSES
Solvent-borne paints and coatings may be
applied to a surface in a number of ways.
Architectural or trade-sales paints are applied by
brush or hand roller, but may be sprayed by
professional painters on large exterior surfaces.
Industrial coatings are applied on a production
line using one of a number of processes and then
cured, usually by an accelerated curing
operation. Coating processes used for solvent-
borne trade-sales paints do not differ significantly
from those used for other liquid paints like
water-borne coatings. The coating processes in
industrial applications can, however, differ
significantly, since the coating may be in liquid
or solid form. Typical processes for applying
solvent-borne (liquid) industrial coatings and the
film formation process are discussed briefly
below.
Dip, Flow, Curtain, Roller, and Coil Coating
Dip coating includes hand-dipping, automatic
dipping, rotational dipping, and other methods
for dipping articles in a tank filled with a paint or
coating. Flow coating is a variation of dip
coating where the paint is either allowed to flow
over the objects or the paint is directed at the
objects from nozzles. Curtain coating is, in
effect, a variation of flow coating used for large,
flat panels, which may have raised moldings.
The panels are carried on a conveyor through a
curtain of paint that flows from a pressure head.
With roller coating, paint is applied by
transfer from rollers to one or both sides of flat
materials. Coil coating, a variation of roller
coating, is used to coat metals in the form of a
continuous strip.
Spray Coating Methods
There are numerous spray methods for
applying paints and coatings, including the
conventional air-assisted, hot-airless,
electrostatic, and combination methods. In
general, spray methods use specially designed
spray guns to atomize the paint into a fine spray,
which is directed at the object to be painted.
For industrial applications, the paint is
typically contained in a pressure vessel and fed to
the spray gun using compressed air. Air-spray
processes have a certain amount of overspray
and rebound from the sprayed surface, which
results in paint-laden air. Application
efficiencies are as low as 20 percent for
conventional air-spray processes.12 Spray booths
with an open front and exhaust at the rear are
used to remove the overspray as it is generated.
In hot-airless applications, the paint is heated
to reduce its viscosity, which allows paints with
higher solids content (i.e., less solvent) to be
used. Fluid pressure at the gun orifice is used in
airless spray applications so that the pressure
drop at the nozzle, when the paint is released,
will atomize the paint. Airless spray guns have
reduced overspray and rebound and have higher
application rates.
Electrostatic spray guns are based on the
principle that negatively charged objects are
attracted to positively charged objects. The
article to be painted is usually attached to a
grounded conveyor. A system of electrodes or
wires are used to create an electrostatic field
between the electrodes and the article. Atomized
paint from a conventional spray gun is injected
into the field where it acquires a negative charge
and is attracted to the grounded article.
Electrostatic spray systems are very efficient
(application efficiencies as high as 90 percent)
and have low operating costs. The initial capital
investment, however, is high, and careful control
of the solvent concentration is required.13
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PART D; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Film Formation
The film formation process is the
transformation of the applied coating into a solid
film that adheres tightly to the substrate. The
quality and characteristics of the final film
depend on the composition of the paint, the
nature and pretreatment of the substrate, and the
processing conditions of application and film
formation.
Physical drying and chemical drying are the
two general routes of film formation. Physical
drying paints and coatings rely on the
evaporation of the carrying agent (e.g., solvent,
water) from the applied coating (polymer
solution or dispersion) to create a solid film.
These paints are characterized by a low solids
content due to the low solubility of the
thermoplastic polymers. Binders of physically
drying paints and coatings include cellulose
esters, vinyl resins, thermoplastic acrylic resins,
and polyurethanes. All physically dried coatings
are sensitive to solvents that swell or dissolve
them.14
Chemical drying paints and coatings create a
film by the cross-linking of the binder through
oxidative reactions (absorption of oxygen to form
ether bridges). The oxidative reactions can be
initiated by heat, surface catalysts, or radiation
(e.g., infrared, ultraviolet). Characterized by a
high-solids content, chemically drying paints and
coatings employ polyester, epoxy, alkyd, vinyl,
and acrylic resins in conjunction with cross-
linking agents such as phenolic and amino resins
and isocyanates.15
ENVIRONMENTAL RELEASES OF 33/50
ORGANIC SOLVENTS FROM THE
PAINTS AND COATINGS INDUSTRY
Environmental releases from the use of 33/50
organic solvents in the paints and coatings
industry occur from the chemical manufacturing
process through the application of paints and
coatings to the final disposal of paint residuals.
The following sections present environmental
releases of organic solvents from the production
and distribution of paints and coatings and
estimates of releases from with their application.
Environmental Releases from Production
Releases and transfers of the 33/50 organic
chemicals from their production facilities
reported in the 1991 TRI were discussed in
Chapter 2. By using a life cycle approach, a
significant fraction of the releases of MEK and
MIBK from production facilities can be
associated with the paints and coatings industry,
since it is the largest end-use for these chemicals.
Since toluene and xylene consumption in paints
and coatings is small compared to other uses for
these chemicals, a much smaller fraction of the
losses of toluene and xylene from petroleum
refineries can be attributed to the paints and
coatings end-use. Again, using a life cycle
approach, some of the toluene, xylene, MEK,
and MIBK losses from distribution facilities are
associated with their distribution to paints and
allied products manufacturers (SIC 2851).
Distribution facilities are not currently required
to report releases and transfers in the TRI.
The 1991 releases and transfers of toluene,
mixed xylenes, o-xylene, MEK, and MIBK from
paints and allied products manufacturers reported
in the TRI are shown on Table 8.2. Almost 7.5
million pounds of these chemicals were released
on-site to the environment (mainly to air) from
paints and allied product manufacturing facilities
alone. Another 4.8 million pounds were
transferred to off-site treatment or disposal
facilities. By using safe substitutes with reduced
or eliminated 33/50 organics, these on-site
releases to the environment and off-she transfers
of the toxic 33/50 organics could be reduced or
eliminated.
Environmental Releases from the Paints and
Coatings Process
Emissions of volatile organic air pollutants
occur from the application of solvent-borne
paints or coatings. At large industrial facilities
these emissions are typically controlled by use of
add-on control devices that either destroy or
collect the organic solvents for reuse or disposal.
156
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157
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PARTII; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
The principal control devices are catalytic and
noncatalytic incinerators, activated carbon or
other types of absorbers, liquid scrubbers, or
refrigerated condensers.
Even with control devices, substantial releases
of organic solvents occur from industrial paint
and coating production lines. In addition,
smaller facilities like automobile repair shops
may not use control devices. Further, pollutants
are usually allowed to evaporate directly to the
atmosphere during consumer application of
trade-sales paints.
No attempt was made to obtain the releases
and transfers of the 33/50 organic chemicals
from industrial paints and coatings processes
from the 1991 TRI, since this use is spread
across numerous industry groups. However,
EPA has developed air emission factors for
solvent losses from paints and coatings
applications. EPA estimates that all toluene and
87 percent of the xylene isomers used in paints
and coatings are emitted to the atmosphere when
the emissions are uncontrolled.16 No emission
factors are available for MEK and MIBK used in
paints and coatings, but it can be assumed that,
like toluene and xylene, virtually all these
solvents are eventually released to the
atmosphere. Applying these uncontrolled
emission factors to the estimated consumption of
33/50 organic solvents in paints and coatings (see
Table 8.1), 1.5 billion pounds of 33/50 organic
chemicals could have been released to the
environment from paints and coatings in 1989.
The actual amount was likely much smaller due
to controls on larger sources.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
The manufacturing and use of solvent-based
paints and coatings result in a number of health
and environmental concerns. Areas that have a
number of paint-consuming industries may have
an appreciable amount of atmospheric pollution
by organic solvents.17 These problems have
prompted a number of states to promulgate
regulations to control releases of VOCs from
paints and coatings. The 33/50 chemicals used
as solvents in paints and coatings are all VOCs
which degrade in the atmosphere and contribute
to photochemical smog formation. State or local
regulations typically impose limits on the
concentrations of solvents in paints and coatings,
or on release rates from the industrial
consumption of paints and coatings. In addition,
EPA established a number of New Source
Performance Standards (NSPS) for several types
of surface-coatings lines in the 1980s. The
NSPS establish maximum allowable emission
rates of VOCs based on the volume of paint or
coating consumed.
When a consumer paints the interior or
exterior of a house or other surfaces, the
solvents evaporate directly to the atmosphere as
the paint dries. This and industrial uses of
paints and coatings result in the environmental
release of several hundred million pounds of the
33/50 organics each year.
Under Clean Air Act scheduling, VOC
regulations for architectural and industrial
maintenance paints and coatings were due by the
end of 1993. These regulations will require
VOC emissions in 1996 to be at least 15 percent
below 1990 levels in ozone non-attainment
areas.18 Other requirements of the proposed
regulations include a 25 percent reduction (from
1990 figures) in VOCs for all paints, excluding
specialty paints, by 1996 and a 45 percent
reduction by 2003.19
Despite state or federal regulations and the
use of control technologies in industrial
processes, there are still substantial releases of
organic solvents from paints and coatings. In
addition, it is difficult to prevent inhalation of
solvent vapor by workers during the production
and use of paints and coatings.20 Studies of the
neurotoxic effects found in workers in industrial
paint and coating applications have described
symptoms like fatigue, difficulty in
concentrating, and short-term memory loss.
These symptoms have not been observed in
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CHAPTERS: PAINTS AND COATINGS
painters in the architectural sector who mainly
use water-borne paints.21
Consumers who use solvent-borne paints may
be most at risk from inhalation of toxic vapors,
since the average consumer probably does not
wear respiratory protection and has inadequate
ventilation in the indoor work area. Further,
household disposal of trade-sales paint residues
represents a large and poorly documented part of
the nation's hazardous wastestream. Thus, use
of safe substitute technologies by industry and
alternative formulations by consumers would
substantially reduce the nation's hazardous waste
burden and the release of toxic air pollutants.
EVALUATION OF SUBSTITUTES
The increasingly stringent government
regulations affecting the paints and coatings
industry' and cost of compliance have spurred the
development of a number of safe substitutes for
solvent-borne paints and coatings. These safe
substitutes include the following:
• product redesign to eliminate unnecessary
paints and coatings;
• water-borne paints;
• liquid high-solids paints;
• aqueous dispersions; and
• powder coatings.
Where applicable, these safe substitutes are
quickly gaining acceptance in both the consumer
and industrial sectors. In 1993, one source
estimated water-borne paints represented 15
percent of the entire paints and coatings market
(including original equipment manufacturing
(OEM), industrial coatings, and architectural
coatings sectors), liquid high-solids paints
represented 11 percent, and powder coatings two
percent.22 Another source placed the market
share for water-borne paints and coatings even
higher: nearly 20 percent of the OEM coatings
sector, more than 55 percent of the architectural
coatings sector, and 18 percent of the industrial
coatings sector.23
Product Redesign
Paints and coatings are applied to a substrate
to improve its appearance or provide an
engineering function. Many manufacturers are
finding that they can eliminate unnecessary paints
and coatings used only for appearance purposes.
Not only does this reduce capital, operating, and
maintenance costs, it also reduces their potential
liability from toxic chemical use. Furthermore,
the elimination of unnecessary paints and
coatings has ramifications beyond the reduction
in use of the 33/50 chemicals used as carrying
solvents. It also reduces the use of the following:
• inorganic pigments made from the 33/50
metals;
• organic pigments made from the 33/50
aromatics;
• resins (binders) made from the 33/50
aromatics and cyanides;
• additives such as plasticizers made from the
33/50 aromatics; and
• paint strippers made from dichloromethane
(see Chapter 11) that are used by industry to
clean paint from equipment or by consumers
to remove old or peeling paint from a
substrate.
Many manufacturers are eliminating
unnecessary paints and coatings only used for
appearance. Others are switching to less
polluting, solvent-free or low VOC substitutes.
Water-borne paints are gaining popularity in the
trade sales sector.
One manufacturer of automobile parts, for
example, has found that consumers do not care if
certain parts are painted if the paint does not
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
provide an engineering function. This
manufacturer has eliminated the unnecessary
paint and saved money by reducing the amount
of materials and equipment used in painting and
paint stripping, and material handling and
disposal costs. In addition to these and other cost
savings, reducing the use of toxic chemicals in
the workplace has improved working conditions
and resulted in numerous intangible benefits such
as improved consumer perception.
Manufacturers who are considering product
redesign to eliminate unnecessary coatings must
consider the substrate and its characteristics
without a coating. If the coating is needed to
provide an engineering function, such as
improved corrosion resistance, one option may
be to change to a base material that does not
require a coating. Whether the coating is applied
to a substrate to improve its appearance or to
provide an engineering function, however, the
challenge for manufacturers who want to
eliminate unnecessary painting processes can be
to convince their clients that painting is not
necessary.
Water-Borne Paints and Coatings
Water-borne paints and coatings have the
widest potential as safe substitutes for traditional
solvent-borne paints, especially in the trade-sales
sector. Water-borne paints are categorized as
containing water-soluble or water-dispersible
binders, depending on the use of water in the
product (i.e., as a solvent or diluent).
Water-Soluble Paints. Water-soluble
binders are relatively low molecular mass
polymers such as alkyds, polyesters,
polyacrylates, epoxies, and epoxy esters. The
individual molecules of the water-soluble
polymers dissolve in water due to salt formation
involving functional anionic or cationic groups.
Most water-soluble binders are anionic, although
cationic electrodeposition paints are also used.
Electrodeposition coating is a technology in
which negatively or positively charged paint
particles are deposited from aqueous solutions
onto metallic substrates by application of an
electrical field. Primers for metal parts are
frequently applied by electrodeposition.
Water-soluble binders are generally produced
via polycondensation or polymerization reactions
in an organic medium. As a result, they
generally contain organic co-solvents like
alcohols, glycol ethers, or other oxygen-
containing solvents that are soluble or miscible
with water (organic content less than 10 to 15
percent). Because of viscosity anomalies, water-
borne paints made with water-soluble binders
have only about 30 to 40 weight-percent solids
content.24
Water-soluble binders can be physically,
oxidatively, or oven dried; oven drying
chemically cures binders with cross-linking
agents. Water-soluble paints and coatings may
be applied by a number of methods, including
dip coating, flow coating, spray coating, and the
electrodeposition method described above.
Water-soluble coatings tend to be water-sensitive
due to the nature of the soluble polymer system.
The coatings, however, have a high gloss, high
level of corrosion protection, and good pigment
wetting and stabilization which are comparable to
solvent-based systems.
Water-Dispersible Paints. Water-dispersible
paints are the largest product group worldwide in
the paint and coating industry.25 Dispersion
paints are also commonly known as latex paints.
Latex is a generic term used to describe a stable
dispersion of insoluble resin particles in a water
system. Use of water-dispersible paints in the
U.S. accelerated after World War II because of
the decline in postwar demand for styrene-
butadiene rubber. Thus, part of styrene-
butadiene rubber production capacity was
converted to styrene-butadiene latex. Elsewhere,
the lack of natural raw materials like vegetable
oils for alkyd resins spurred the changeover to
synthetic resins.
Most water-dispersible paints dry physically
by evaporation of water under ambient
conditions. They are also noncombustible in
liquid forms, and can be cleaned up with water.
Dispersion paints can be used on many types of
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CHAPTERS: PAINTS AND COATINGS
substrates in both consumer and industrial
applications. Many dispersion coatings that form
films and dry at temperatures greater than 40°C
are used for the industrial coating of plastic
articles and metals.
Resins used in dispersion paints include vinyl
acetate co-polymers, vinyl propionate co-
polymers, aerylate-methacrylate co-polymers,
styrene-acrylate co-polymers, and styrene-
butadiene polymers. Dispersion paints contain
small amounts of organic solvents (usually less
than five weight-percent) as coalescing agents
that evaporate on drying.26
Vinyl acetate co-polymers and vinyl
propionate co-polymers can be formulated to be
particularly elastic or weather resistant.
Acrylate-methacrylate co-polymers are highly
weather resistant and are used for house paints
and for water-borne industrial paints. Styrene-
acrylate co-polymers are used in interior-use
paints,, plasters, and some exterior-use paints.
The water absorption and elasticity of these
polymers decrease with deceasing styrene
content. Styrene-butadiene polymers have low
water uptake but tend to undergo chalking, and
are thus used primarily as interior paints.
Besides water, resin, and pigment, water-
borne dispersion paints contain extender auxiliary
agents such as dispersants and protective colloids
and emulsifiers, thickeners, and preservatives.
Presei"vatives are used to prevent microbial
growth in stored emulsion paints. One problem
with latex paints had been the addition of
mercury to prevent formation of mold and
mildew. As the paint dries, mercury vapors
were released into the air. This use of mercury
was eliminated several years ago from interior
latex paints, and recent developments in
alternative chemical additives has virtually
eliminated this use of mercury in all paints and
coatings.
Dispersion paints have relatively high solids
content (50 to 60 weight-percent).27 Because the
binder is in paniculate form, only a low gloss
and, in some cases, only limited corrosion
protection can be achieved. This limited
corrosion protection is due to the films increased
permeability, which makes it difficult for them to
pass salt spray and humidity tests. For example,
porous masonry surfaces may experience
migration of soluble salts though the film to leave
a white deposit on the surface of the coating. On
the other hand, the increased permeability of
water-borne dispersion coatings allows these
coatings to "breathe," or allow moisture vapor to
pass through. This decreases the chance for
moisture build-up on the substrate which reduces
the chance for blistering or peeling. Emulsion
paints are less susceptible to blistering and
peeling than most solvent paints.28 Because of
their rapid drying properties, water-borne
emulsions have only limited use for electrostatic
coating and dipping applications. They can be
applied by spraying.
Not all properties of solvent-based paints,
however, are available with the water-borne
alternatives. As discussed above, high gloss and
wear resistance are available only from selected
paint formulations. Also, water-borne paints and
coatings will not remain stable on the shelf as
long as solvent-based paints.
No-VOC Water-Dispersible Paints. In
1992, Glidden began to market a no-VOC
interior latex paint, Spred 2000, in a limited
number of colors. Spred 2000 uses a new
technology to form the polymer dispersion,
which alleviates many of the problems
encountered by other manufacturers who have
attempted to use traditional latex technologies
and no VOCs. With this new technology, the
film formed by the no-VOC paints exhibits
characteristics similar to traditional low-VOC
latex paints, without the need of a solvent. The
paint has tinting capabilities and no odor after
application. Glidden is marketing Spred 2000 as
a high quality, interior wall paint. After two
years on the market, Spred 2000 is doing well in
states that have VOC regulations, such as
California. Glidden has plans to make all of its
paint products without VOCs by the end of the
decade. Another paint manufacturer, ICI
Subsidiaries, set the year 2000 as the target date
to eliminate all VOCs from its decorative
architectural coatings.29
Applications for Water-Borne Paints.
Water-borne paints have quickly taken hold in
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
the consumer market, but have been less
accepted in market sectors with exceptionally
high appearance or engineering requirements,
such as the automotive industry In recent years,
however, the automotive OEM sector has
increased its use of water-borne paints and
coatings in all but the heaviest-coat
applications.30 An estimated 20 percent of this
sector now uses water-borne paints, and that
percentage is growing each year.31 With
improved water-borne paint technology,
manufacturers have been able to change from
solvent-borne to water-borne coating systems and
meet emissions regulations while maintaining
their ultrahigh finish standards.32
Traditionally, automobiles are painted using a
complicated, four-coat system: an electrocoated
primer, a primer-surfacer, a basecoat, and a
topcoat/clearcoat. The market for basecoats is
moving progressively toward water-borne
systems, with powder coatings gaining a stronger
market share of the primer, primer-surf acer, and
topcoat/clearcoat applications. Du Font's
Generation 4, a water-borne epoxy/polyurethane
coating, is currently in use in five automotive
assembly plants in North America. PPG
Industries is marketing a "full-line" water-borne
solution to the traditional solvent-based, four-step
system. This switch by the automotive industry,
with its extremely high performance standards, is
indicative of the quality and performance that can
be achieved using water-borne systems. If the
automotive industry can change from solvent-
borne coatings to water-borne coatings, other
industries with similar or less stringent
performance requirements should also be able to
make the switch.33
Hybrid Paints. Hybrid systems consist of
combinations of water-soluble and water-
dispersible binders. The hybrid systems allow
compensation for the disadvantages of water-
soluble binders that have low solids and high
organic solvent contents and water-dispersible
paints that can have problems with film
formation. These hybrid binders are now being
used as aqueous metallic base paints for
automotive coatings and finishes. Hybrid
systems generally contain about ten percent
organic solvents.34
Management of Waste Paint. Many
communities have begun collecting latex paints
from the household wastestream to reduce the
wastes, hazardous or not, entering landfills and
incinerators. In 1990, most programs collected
latex paints in their original containers or
consolidated them in large containers for use
without additional processing. The most
successful "drop and swap" programs have been
able to identify markets for the collected
materials.
Paint manufacturers are also developing
methods for recycling paints collected from
communities and industry. Major Paint, a
manufacturer of latex paints, markets three
architectural latex paints, Cycle II latex flat,
semi-gloss, and primer coatings, made from
recycled materials. In the past, manufacturers
have had difficulty recycling paint collected from
consumers because the paint is frequently
contaminated. Major Paint uses a proprietary
filtering process and controlled collection
practices to sidestep the problems of unknown
and cross contamination of the recycled paints.
The collected material is mixed with virgin paints
and marketed through the federal General
Services Administration (GSA) as 50 percent
recycled paint (15 percent post-consumer waste).
Green Paint Company of Massachusetts has
marketed similar recycled products. The GSA in
November, 1993 issued draft performance
specifications for recycled latex (TTP-28-46) that
include a specified minimum post-consumer
content, maximum VOC level of 200 g/1, and
maximum mercury concentrations.
35
High-Solids Paints and Coatings
EPA defines high-solids paints as systems
with volatile organic contents of less than 2.8
pounds per gallon. High-solids paints are
defined elsewhere as paints with more than 85
percent solids content by weight. In practice,
paints with a solids content of 60 to 80 percent
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CHAPTERS: PAINTS AND COATINGS
may also be called high-solids paints, especially
if the equivalent solvent-borne paint contains
more than 50 percent solvent.36
Oil-based paints and varnishes were the first
widely used low-solvent paints, but their use has
been largely displaced by the new high-solids
paints developed in response to stricter
environmental regulations. Today, high-solids
paints include low-solvent and solvent-free
paints,
To achieve solids contents exceeding 70
percent, the binder in a high-solids paint must be
modified to have a much lower intrinsic viscosity
than binders of conventional solvent-borne
paints. This is usually achieved by developing
special binders with reduced number-average or
weight-average molecular mass. Nonvolatile
reactive diluents, metal compounds, or organic
compounds as cross-linking agents are also used.
Cross-linking agents assist the reaction of low
molecular substances and/or polymers to form
macro-molecules. Lead and tin compounds have
proved particularly suitable as cross-linking
agents ,37 The extent of the use of lead and tin for
this application was not reported in the literature.
The binders used in high-solids paints include
alkyd resins, polyester resins, polyurethanes,
acrylic resins, epoxy resins, and poly (vinyl
chloride) plastisols. High oil, oxidatively drying
alkyd resins are used as maintenance and
architectural (trade-sales) coatings. These
coatings have a solids content of 85 to 90 weight-
percent. Nondrying alkyd resins cross-linked
with rnelamine resins during heat-curing are used
for industrial coatings.
Low molecular mass polyesters formulated
with rnelamine resins, isocyanates or
polyisocyanates are used in high-solids paints,
although high quality paints with a solids content
exceeding 70 weight-percent are not widely
available. This type of high-solids paints is more
widely used for architectural coatings than
industrial coatings because of the possibility of
postcombustion of the solvent.38
Poiyurethane-based high-solids paints are
being used in both the architectural and industrial
sectors. Aliphatic isocyanates with a high
yellowing resistance are seeing increased use. In
addition, low-viscosity polyurethane oligomers
are combined with polyester, acrylic, and alkyd
resins as modifiers for water-borne and low-
solvent binders that improve the hardness and the
flexibility of the paint film. Epoxy resins are
also used with high-solids paints based on
acrylic, polyester, or alkyd resins.
Besides the reduction of pollution and the
improvement in safety that results from using
less solvents, there are several advantages to
high-solids paints. High-solids paints save
materials, energy costs, and transportation costs.
They also provide higher layer thicknesses per
application cycle which results in time savings.
Perhaps most importantly, high-solids paints can
be applied with conventional equipment, which
makes them readily accessible to small- and
medium-sized facilities and users of trade-sales
paints.
High-solids paints must rely on the binder to
provide flowability and prevent sagging on
vertical surfaces or wrinkle formation. The
binder is also responsible for controlling the
drying behavior. In a high-solvent paint, these
properties are provided, in part, by the solvent.
Beyond the possible limitations of providing
these properties with a binder, no barriers to the
use of high-solids paints were identified in this
study.
Powder Coatings
Powder coatings are powdered resins which
are applied to a substrate and heated to ruse the
resin into a uniform, continuous film. Less than
one percent solvent is used in powder coatings
and the application process is almost pollution-
free.39 Easy collection and reuse of powdered
over-spray is one attribute of powder coating that
accounts for its limited waste generation.40 In
addition, the method eliminates the fire and
toxicity hazards associated witji the use of
solvent-based paints and also shows savings in
cost.41
There are three main methods in use for
application of powder coatings: fluidized bed,
electrostatic spray, and hot flock. The
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
electrostatic spray process has a substantially
larger market share than in the fluidized bed and
hot flocking processes, and is discussed below.
In the electrostatic process, electrostatic
forces are used to coat a part with a fine layer of
powdered resin. This is accomplished by
charging the powdered coating and directing
them toward the substrate to be coated. The
powdered particles, dispersed and conveyed in
an air stream, acquire their charge by passing
through a high voltage source. The particles are
then attracted and held to the substrate, which is
grounded, through electrostatic forces. The
substrate is subsequently heated in an oven, or
chemically activated (e.g., by infrared), to fuse
the particles to the substrate and each other to
create a continuous film. The thickness of the
powdered layer on the substrate is self-limiting
and determined by the combination of powder
and source of electrostatic charge.42
Coating powders are frequently separated into
decorative and functional grades; decorative
grades generally have a finer particle size than
functional grades. Powders are also divided
between thermosetting and thermoplastic resins.43
Of the thermosetting coating powders, epoxy and
polyester-urethane binders had the most
production capacity in the U.S. in 1988,
accounting for 29 and 32 percent, respectively,
of capacity. Polyester-trisglycidyl isocyanurate
(21 percent) and epoxy-polyester (17 percent)
were next, while acrylic powder coatings only
had one percent of the production capacity for
thermosetting coating powders.44 Conversely,
epoxy-polyester resins dominate the coating
powder market in Europe, where they account
for 55 to 60 percent of capacity.45 The
thermoplastic coating resins include polyvinyl
chloride, poly amides, cellulose esters, and
polyethylene-propylene .46
The use of powder coatings in industrial
applications produces the least environmental
pollution of any of the current coatings
technologies. No paint slurry is generated during
their application, and dust-air mixtures are easily
separated. Powder overspray is easily
recovered. Finally, the coating powders are
virtually solvent free and generally cure by
polyaddition.
The environmental benefits and the lack of
environmental legislation affecting their use or
disposal are two reasons why powder coatings
are seeing increased use. In addition, powder
coatings are economical and are applied using
simple, easily-to-automate methods, thus
minimizing the training required for operators.
Powder coatings also have good film properties,
coat corners well, and may be applied in a wide
range of thicknesses.
Disadvantages of powder coatings include
problems with color changes and limited
applicability of the technology. Color matching
is more difficult with powder coatings than with
solvent coatings. Since powder coatings
materials are discrete particles, each of which
must be the same color, there can be no tinting
or blending by the user. Color must be available
from the manufacturer. Finally, the high
temperature required to cure the powder coat
makes the process applicable only for metals and
some plastics that can withstand the temperature
extremes.
Powder Coatings in the Automotive
Industry. In February, 1993 the Big Three auto
manufacturers, GM, Ford, and Chrysler, formed
a consortium to explore the expanded use of
powder in primer and clearcoat systems. The
Powder Coatings Institute anticipates a 12
percent annual growth rate for powder coatings
through 1996; another source predicts a lesser
growth rate of six to seven percent. Currently,
metal finishing, appliances, lawn and garden,
and architectural applications of powder coatings
represent 53 percent, 21 percent, 8 percent, and
3 percent, respectively, of the total powder
coatings market.47
Aqueous Powder Suspensions
Aqueous powder suspensions (APS) are
powdered resins in slurry form which can be
applied with conventional spray guns. They can
also be applied by airless spraying, dip coating,
electrostatic spraying, and reverse roller coating.
APS products do not contain organic solvents and
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CHAPTERS: PAINTS AND COATINGS
can be applied in thinner films than powder
coatings.
The APS system is a liquid-solid system
which consists of a dispersion of powdered
resins, pigments, hardeners, and other additives
in water. APS systems do not contain
emulsifiers. The typical solids content of an
APS paint or coating is from 20 to 30 percent.
Thus,, they have the disadvantage of requiring
more energy for curing than powder coatings or
other water-borne systems.
Compared to powder systems, APS systems
eliminate the hazard of powder dust. They can
also be shaded more easily, and colors switched
quickly on the production line. The cost of APS
systems is slightly higher than that of powder
because their manufacturing process includes an
extra wet-grinding step, APS paints and coatings
can be used for nearly all types of industrial
applications.
Conclusions
In the industrial sector, powder coatings
appear to offer the best environmental alternative
to solvent-based paints made with the 33/50
chemicals, since these paints completely
eliminate the use of the solvent. Water-
dispersible paints are the best choice for the trade
sales sector since they have the lowest organic
solvent content of the water-borne safe
substitutes. In addition, paint manufacturers
have begun to introduce VOC-free water-
dispersible paints, such as Glidden's Spred 2000,
no-VOC latex paint. Fortunately, these safe
substitutes for solvent-borne paints are rapidly
taking hold in industry and the trade sales sector.
In fact, water-borne paints held about 80 percent
of the interior coatings market in 19904* when
powder coatings held eight to nine percent of the
total industrial coating market. Currently,
powder coatings cannot be used in some sectors
of the industrial market, like large outdoor
applications such as bridges and ships. When
these sectors are excluded, powder coatings held
a 15 percent share of the available industrial
market in 1990.49
The safe substitutes for solvent-borne paints
are not without environmental disadvantages,
however. Many of the resins used in these paints
(methyl methacrylate, polyurethane and styrene-
butadiene, to name a few) are made from 33/50
chemicals. Variations of these same resins are
also used, however, in high-solvent paints.
Whatever the type of paint, therefore, the best
environmental solution may be to redesign the
product to eliminate unnecessary paints and
coatings.
Despite the potential health and environmental
issues associated whh the resins used in
substitutes for solvent-borne paints and coatings,
the substitutes represent a big step toward
preventing the release of toxic organic solvents
by use of safe substitutes. Further research and
development should be encouraged to develop
substitutes that, for example, meet the
appearance requirements of the automotive
industry or water-borne paints that have an
extended shelf-life. Substantial reductions in the
nation's hazardous waste burden and the release
of toxic chemicals will be achieved as more
industries and consumers switch to the sate
substitutes. Industry and consumer interest also
provides the impetus for paint manufacturers to
increase their research in these areas.
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENDNOTES
1 "Waterborne Systems Gaining Niche by Niche," Chemical Marketing Reporter, October 20,
1990.
Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1990),
2
Vol. A18.
3 G.A. Lorton, "Waste Minimization in the Paint and Allied Products Industry " JAPCA
Vol. 38, No. 4.
4 Ullmann 's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag 1990)
Vol. A18.
5 Ibid.
6 W.M. Morgans, Outlines of Paint Technology, 3rd ed., (New York: Halsted, 1990).
7 Ibid.
8 Ibid.
9 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag 1990)
Vol. A18.
10
11
W.M. Morgans, Outlines of Paint Technology, 3rd ed., (New York: Halsted, 1990).
Swaraj Paul, Surface Coatings: Science and Technology, (New York: John Wiley, 1985).
12 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag 1990)
Vol. A18.
13 Ibid.
14 Ibid.
15 Ibid.
16 Anne A. Pope, et. al., Toxic Air Pollutant Emission Factors: A Compilation for Selected Air
Toxic Compounds and Sources, 2nd ed., US EPA, (Research Triangle Park, NC, 1990).
17 W.M. Morgans, Outline of Paint Technology, 3rd ed., (New York: Halsted, 1990).
18 "Coatings '93 No Clean Winner," Chemical Marketing Reporter, October 25, 1993.
19 "Proposed Rule Would Regulate Fumes From Paints, Other Coatings, EPA Says," Environment
Reporter, Vol. 24, No. 14, August 16, 1993.
Paul Kemezis, "EPA Rulemaking on VOCs Pits the Small Against the Large " Chemical Week
October 13, 1993.
166
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CHAPTERS: PAINTS AND COATINGS
20
W.M. Morgans, Outline of Paint Technology, 3rd ed., (New York: Halsted, 1990).
21 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1990),
Vol. A18.
22 "Coatings '93 No Clear Winner," Chemical Marketing Reporter, October 25, 1993.
23 Ibid.
24 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1990),
Vol. A18.
25 Ibid.
26 Ibid.
27
Ibid.
28 Charles R. Martens, Waterborne Coatings: Emulsions and Water-Soluble Paints, (New York:
Van Nostrand Reinhold, 1981).
29 "Glidden 'No-VOC Architectural Latex Paint Set to Bow," American Paint and Coatings
Journal, April 3, 1992.
Correspondence with Jim Sainsbury, Glidden Representative, April 26, 1994.
30 Andrew Kagen, "Waterborne Coatings Take Hold in U.S. Automotive Market," Chemical
Week, October 14, 1992.
31 "Coatings '93 No Clean Winner," Chemical Marketing Reporter, October 25, 1993.
32 Andrew Kagen, "Waterborne Coatings Take Hold in U.S. Automotive Market," Chemical
Week, October 14, 1992.
33
Ibid.
34 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1990),
Vol. A18.
35 Carolyn Dann, "The Latest on Latex Paint," Household Hazardous Waste Management News,
June 1993.
"Federal Focus," Household Hazardous Waste Management News, December 1993.
36 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1990),
Vol. A18.
37 Ibid.
38 Ibid.
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
39 Charles R. Martens, Waterborne Coatings: Emulsions and Water Soluble Paints, (New York:
Van Nostrand Reinhold, 1981).
40 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wilev 1981)
Vol. 19. y'
41 W.M. Morgans, Outlines of Paint Technology, 3rd ed., (New York: Halsted, 1990).
Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wiley, 1981),
42
Vol. 19.
44
Vol. A18.
43 Ibid.
Ullmann's Encyclopedia of Industrial Chemistry, 3rd ed., (Weinham: VCH Verlag., 1990),
45 Charles R. Martens, Waterborne Coatings: Emulsions and Water-Soluble Paints, (New York-
Van Nostrand Reinhold, 1981).
46 Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., (New York: John Wilev 1981)
Vol. 19.
48
1990.
49
"Coatings '93 No Clear Winner," Chemical Marketing Reporter, October 25, 1993.
"Waterborne Coatings Gaining Niche by Niche," Chemical Marketing Reporter, October 29,
"Powders Advance Bearing Benefits," Chemical Marketing Reporter, October 29, 1990.
168
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CHAPTER 9
MATERIALS AND PARTS DECREASING
Materials and parts degreasing is a process to
clean organic materials, water-soluble inorganic
salts, and insoluble particles from manufactured
materials or parts. Four of the six 33750
halogenated organic chemicals: dichloromethane
(DCM), tetrachloroethylene (PCE), 1,1,1-
trichloroethane (TCA) and trichloroethylene
(TCE), are used as solvents in industrial
degreatsing applications. The halogenated
organic solvents are used to remove organic
materials like rosins, glycols, oils, greases, and
waxes from the substrate. Removal of the
organic materials will often free the insoluble
particles from the substrate.
Concerns about the toxicity of halogenated
solvents and the impending phase-out of TCA as
an ozone depleting substance have resulted in the
recent development of a number of substitutes
for solvent degreasing processes. This chapter
presents the use of and substitutes for the 33/50
halogenated organic chemicals in degreasing
applications.
INDUSTRY PROFILE
Materials and parts degreasing are an integral
part of many industrial processes, including the
manufacturing of automobiles, electronics,
furniture, appliances, jewelry, and plumbing
fixtures. Degreasing is also frequently used in
the textiles, paper, plastics, and glass
manufacturing industries. The five major
industry groups that use halogenated solvents in
degreasing operations are furnitures and fixtures
(SIC 25), fabricated metal products (SIC 34),
electric and electronic equipment (SIC 36),
transportation equipment (SIC 37), and
miscellaneous manufacturing industries (multiple
SIC). With the exception of the furniture and
fixtures industry, each of these were among the
top industries for total TRI releases and transfers
of the 33/50 halogenated compounds in 1991 (see
Table 3.6).
Some of the greatest progress in preventing
pollution has been in the area of solvent
degreasing processes. Concerns about the
potential health and environmental effects of
the 33/50 halogenated solvents have helped
advance the development of safe substitutes.
Degreasing is most often employed as a
surface-preparation process to remove
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PARTH; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
contaminants and prepare raw materials and
parts for subsequent operations like machining,
painting, electroplating, inspection, and
packaging. Traditionally, various organic
solvents, including DCM, PCE, TCA, TCE,
chlorofluorocarbons, petroleum distillates,
ketones, and alcohols, have been used either
alone or in blends in the degreasing process.
Recently, aqueous solvents and other alternatives
such as terpenes have seen increased use.
Quantities of 33/50 Halogenated Solvents Used
in Degreasing
Based on the chemical-use tree for the 33/50
halogenated organic chemicals (see Figure 3.1)
and the 1992 demand data (see Table 3.2),
almost 499.9 million pounds of 33/50
halogenated organic chemicals were used as
degreasing solvents in 1992. Degreasing is the
largest end-use for TCE and TCA, accounting
for 90 percent (103.5 million pounds in 1992) of
TCE consumption and 49 percent (294 million
pounds in 1992) of TCA consumption. DCM
and PCE are used as degreasing solvents on a
much smaller scale; only 11 percent (42.9
million pounds) of DCM and 13 percent (32.5
million pounds) of PCE (1992).
Price of 33/50 Halogenated Solvents Used in
Degreasing
The current prices of the 33/50 halogenated
organic chemicals used as degreasing solvents
range from $0.29 for bulk quantities of PCE up
to $0.64 per pound for bulk quantities of TCA
(see Table 3.3). Other costs associated with
degreasing include solvent recycling or recovery
costs (or solvent replacement costs if the solvent
is not recyclable), energy costs, and waste
disposal costs.
One cost advantage of the 33/50 halogenated
compounds as degreasing solvents is that they are
relatively easy to recycle and recover using
distillation equipment. Waste materials
generated from the degreasing process or from a
solvent recovery system, however, must be
disposed of as a hazardous waste.
DESIRED PROPERTIES OF DEGREASING
SOLVENTS
A good degreasing solvent should have
excellent solvency for a broad range of organic
materials, particularly oils and grease. The
solvent should preferably be nonflammable,
especially in vapor degreasing applications
(described below), and be noncorrosive to the
metals or parts being cleaned and the degreasing
equipment. A good degreasing solvent should
also have low toxicity. Additional properties
desired in a degreasing solvent include a low heat
of vaporization, a high vapor pressure that allows
evaporative drying of cleaned parts, and
chemical stability.
The 33/50 halogenated solvents have been
extensively used in the industrial applications
cleaning, primarily because of their excellent
solvency, nonflammability, and high vapor
pressures. Additionally, their vapors are heavier
than air and thus can be contained somewhat
within the degreasing equipment. Only recently
have health, safety, and environmental issues
concerning their use and disposal contributed to a
decrease in their use as degreasing solvents and
to a search for substitutes.
DEGREASING PROCESS DESCRIPTION
The three basic types of degreasing equipment
are cold cleaners, open-top vapor degreasers,
and conveyorized degreasers.1 The processes for
metal or parts degreasing with these types of
equipment are discussed below.
Cold Cleaning
Cold cleaners are usually the simplest and
least expensive of the three types of degreasing
equipment. Parts are cleaned by being immersed
and soaked, sprayed, or wiped with solvent. A
typical cold cleaner consists of a tank filled with
solvent and a cover for periods of nonuse. More
sophisticated cold cleaners are equipped with
solvent sumps, spray nozzles, drains, and
automatic controls.
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CHAPTER 9; MATERIALS AND PARTS DECREASING
In the basic cold cleaning process, soiled
objects are dipped into the solvent bath to
dissolve the contaminants from their surface.
This cleaning process can be enhanced by
agitating the solvent, or by brushing or spraying
the solvent onto the soiled objects. Cold cleaning
is usually conducted at room temperature and
ambient pressure, although in some cases the
solvent may be heated, but not above its boiling
point. When the parts are removed from the
immersion bath, solvents are allowed to drain
and evaporate from the parts.
Vapor Degreasing
The vapor degreasing process uses the vapor
of the cleaning solvent to remove contaminants
from materials or parts. The vapors, generated
by boiling the solvent, condense on the relatively
cold parts, dissolving and displacing the
contaminants and soils, thus cleaning the surface.
Cleaning ceases when the parts and vapor
temperatures are at equilibrium.
The open-top vapor degreaser is a large tank
with tliree distinct zones: the solvent reservoir,
vapor zone, and freeboard. The solvent
reservoir, which contains the cleaning solvent, is
equipped with electric or steam heater coils to
create the vapor zone by boiling the solvent.
The vapor zone, directly above the solvent
reservoir, is the zone into which the relatively
cold parts are lowered causing vapor
condensation and thus parts cleaning. The vapor
zone height is controlled by cooling coils located
near the top and on the inside perimeter of the
tank. The coils condense the solvent vapors and
return them as liquid to the reservoir. The
density of the solvent vapors, as previously
mentioned, also assists in maintaining a vapor
zone and containing the vapors within the tank.
The freeboard is the vacant space above the
vapor zone which minimizes solvent drag-out
when the parts are removed from the vapor zone
after cleaning. The freeboard space allows
condensed solvent vapors to drip from the
cleaned parts, as well as offering drying time for
the pails. Much of the solvent vapors and liquid
in this zone fall back to the vapor zone and
reservoir.
Vapor degreasing is frequently more
advantageous than cold cleaning because the cold
solvent bath becomes increasingly more
contaminated during the cleaning process. As
the cold bath becomes more and more
contaminated, the relative cleanliness of the parts
may decrease because the parts are in direct
contact with the contaminated liquid solvent. In
vapor degreasing, although the boiling liquid
solvent in the reservoir contains the contaminants
from previously cleaned parts, contaminants
usually boil at higher temperatures than the
solvent, resulting in the formation of essentially
pure solvent vapors. In addition, the high
temperature of vapor cleaning aids in wax and
heavy grease removal and significantly reduces
the time it takes for cleaned parts to dry.
Conveyorized Degreasing
Conveyorized, or in-line, degreasers have
automated, enclosed conveying systems for
continuous cleaning of parts. Conveyorized
degreasers clean by either the cold solvent
process or the vaporized solvent process. While
these units tend to be the largest degreasers, they
actually produce less emissions per part cleaned
than other types of degreasers. This is due
primarily to the enclosed design of the conveyor
systems.
Hybrid Degreasing Systems
Combinations of immersion and vapor
degreasing systems can be employed to aid in the
cleaning of problematic soils (e.g., waxes), or
highly soiled parts. These hybrid units can
utilize agitated solvent baths, spray units and/or
ultrasonics in conjunction with vapor degreasing
processes. Ultrasonics applies energy to a
cleaning solution to induce cavitation, or the
collapse of millions of tiny bubbles produced in
the solution by the applied energy. It is the
collapse of these bubbles that create a scrubbing
effect to clean the immersed parts.2
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENVIRONMENTAL RELEASES FROM
DECREASING
Environmental releases from the use of 33/50
halogenated compounds in degreasing occur
from their production through the degreasing
process and the final disposal of solvent
residuals, as discussed in the following sections.
Releases and Transfers from Production and
Distribution Facilities
Releases from the production of 33/50
halogenated organic were obtained from the 1991
TRI data and discussed in Chapter 3. Total
environmental releases and off-site transfers of
DCM, PCE, TCA, and TCE from production
facilities were more than two million pounds.
Since approximately 37 percent of these
chemicals produced in the U.S. are consumed in
degreasing applications, some fraction of these
releases can be associated with halogenated
solvent degreasing. Similarly, some of the
halogenated organic emissions from distribution
facilities are associated with their distribution to
degreasing facilities.
Almost all of the DCM and TCE sold and
approximately 70 to 75 percent of the PCE sold
are distributed through distribution facilities.
Distribution facilities are not required to report
their emissions in TRI, but in 1983 EPA
estimated that approximately 1.28 million pounds
of DCM, PCE, and TCE combined were emitted
from these facilities.3 DCM contributed almost
85 percent of these emissions, but DCM only
represents about eight percent of the halogenated
organic compounds used in metals and parts
degreasing. No information was available on the
amount of TCA distributed through these
facilities or the amount of TCA emissions from
distribution facilities.
Releases and Transfers from the Degreasing
Process
Environmental releases from the degreasing
process include evaporation losses from solvent
baths, solvent carry-out, and equipment leaks.
Air, water, or land releases occur from solvent
recycle and recovery processes, storage and
handling, accidental spills and leaks, and disposal
of solvent-contaminated residuals as hazardous
waste. Because of the wide-spread use of the
halogenated solvents in various industry groups,
no attempt was made to retrieve the releases and
transfers that could be attributed to degreasing
operations from the 1991 TRI. However, the
magnitude of the environmental releases is
illustrated by estimating air releases from the
degreasing process.
The range of EPA emission factors for
degreasing with DCM, PCE, or TCE is 0.57 to
0.92 pounds emitted per pound of fresh (virgin)
solvent used.4 The lowest emission factor is for
open-top vapor degreasers equipped with control
devices, such as a cover for the tank, a raised
freeboard equipped with a freeboard chiller, and
a carbon adsorber. The highest emission factor
is for a vapor degreaser without control devices.
Applying these emission factors to the almost 500
million pounds of 33/50 halogenated organic
chemicals that were estimated used in degreasing
operations in 1991 indicates that somewhere
between 285 and 460 million pounds were
emitted to air. This does not include losses to
water or land or disposal of hazardous waste
contaminated with the 33/50 halogenated organic
chemicals, but 90 percent of total releases of
these compounds reported in the 1991 TRI were
to air. The lower emission estimate of 285
million pounds correlates well with the total
reported releases and transfers of DCM, TCE,
TCA, and PCE, approximately 300 million
pounds in 1991.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
As discussed in Chapter 3, all of the 33/50
halogenated organic chemicals are toxic, and
DCM, PCE, and TCE are suspected
carcinogens. In addition, TCA is being phased-
out of production as an ozone-depleting
substance, while TCE and PCE are precursors to
photochemical smog formation. Today,
concerns about the toxicity of the 33/50
halogenated solvents and their potential to
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CHAPTER 9; MATERIALS AND PARTS DECREASING
contribute to photochemical smog or ozone
depletion have resulted in a reduction in their use
in degreasing applications.
Still, market sources have indicated that TCE
is being evaluated as a possible substitute
degreasing solvent for TCA, since TCA is being
phased-out of production as an ozone-depleting
substance.5 Ironically, TCA first gained wide
acceptance as a degreasing solvent as a less toxic
substitute for TCE, following wide-spread
concern about the toxicity of and potential for
worker exposure to TCE.
EVALUATION OF SAFE SUBSTITUTES
FOR THE 33/50 DEGREASING SOLVENTS
Safe substitutes approaches to reducing the
use of 33/50 halogenated organic chemicals in
the degreasing process include:
• using no-clean manufacturing methods;
• substituting safe, aqueous, or semi-aqueous
degreasing solvents for the 33/50 halogenated
organic solvents;
• substituting safe, non-aqueous degreasing
solvents for the 33/50 halogenated organic
solvents; and
« substituting non-liquid cleaning technologies
for the degreasing process.
Many of these approaches are already seeing
wide-spread use because of pending or potential
regulations affecting the 33/50 halogenated
solvents and their potential to contribute to
photochemical smog or ozone depletion. The
following sections present evaluations of the
substitutes.
No-Clean Technologies
The most fundamental technique for
eliminating the use of degreasing solvents is to
design processes and/or use materials that do not
require cleaning. This is most readily achieved
when designing new products or new
manufacturing processes. Still, existing facilities
may realize cost savings and dramatically
decreased potential liability by reconsidering
their existing processes and developing
alternative methods that do not require cleaning.
Reconsidering an existing process means
evaluating the present cleaning operation, as well
as the process line, both up-stream and down-
stream of the cleaning step. Up-stream of the
cleaning step, processes that introduce the soils
(oils, greases, etc.) that must later be removed
should be evaluated to determine whether
alternative materials can be substituted that do
not require cleaning, or whether the soil material
can be eliminated completely. An example of a
no-clean technology is the replacement of
lubricating oils with a mineral spirit-based
"evaporative oil." Due to its relatively high
vapor pressure, the mineral spirit-based oil can
be removed using flash-drying or other
technologies such that the substitute does not
require cleaning prior to subsequent operations.
Considering process requirements down-
stream, the current degree of cleanliness
specified may not be required to satisfactorily
perform the next manufacturing step. In some
cases, cleaning may not be required at all.
Further, the manufacturing processes can
sometimes be rearranged to require fewer
cleaning steps.
Developing alternative methods that do not
require cleaning means reevaluating the steps in
the manufacturing process which introduce
materials that must be cleaned. For example, the
printed circuit board industry has developed no-
clean flux technologies that eliminate the need to
clean flux from some printed circuit boards.
Unfortunately, use of new technologies is often
stymied by their lack of working history. In
1992, no-clean flux technologies had not been
introduced into the U.S. Department of Energy
(DOE) Weapons Complex because of concerns
about the long-term reliability of the printed
circuit boards.6 Similarly, other industries that
are required to comply with government
specifications may have difficulty introducing no-
clean technologies that require process
modifications or product redesign.
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Specifications for manufacturing parts for the
military often dictate the type of cleaning solvent
and the cleaning process to be used.
Unfortunately, changing government
specifications is a long and arduous process that
may slow progress in the use of safe substitutes.
No-clean processes require innovative,
optimized manufacturing to eliminate cleaning.
They save time and chemicals and reduce the
regulatory burden and potential liability that
results from using hazardous chemicals. The
disadvantages of no-clean technologies are that
they may require process modifications and even
product redesign.
The most fundamental technique for
eliminating the use of degreasing solvents is to
redesign the production process to eliminate the
need for cleaning. Other technologies, such as
aqueous cleaning systems, are also viable
substitutes.
Aqueous and Semi-Aqueous Solvent
Substitutes
In the metal parts and metal finishing
industries, aqueous and semi-aqueous cleaners
are potential substitutes for solvent vapor
degreasers. Some printed circuit board and
electronic manufacturers have changed to these
systems, however, this industrial sector has been
reluctant to change due to the high degree of
cleanliness needed and lack of documented
successes. Aqueous cleaning solutions include
alkaline solutions, detergents, and hot-water
washes. They are often used with pressure,
agitation, ultrasonics, filtration, or some other
physical process to provide effective cleaning in
many industrial cleaning applications. Semi-
aqueous cleaners are emulsions of hydrocarbon
solvents and water. They can also be used with
pressure, agitation, ultrasonics, or other physical
processes to enhance their cleaning
characteristics. The toxicity and effects of
chronic exposure to many of the semi-aqueous
cleaners have not been fully evaluated.
Significant changes in the characteristics of
wastewater and wastewater flowrate are also
issues that must be considered when changing to
aqueous and semi-aqueous cleaning systems, and
are addressed below.7
Aqueous and semi-aqueous cleaners are not
usually drop-in replacements for halogenated
cleaning solvents. These cleaning alternatives
usually require the addition of rinsing and drying
steps after cleaning to accomplish comparable
solvent degreasing results. Water-based cleaners
have little or no volatile components, which
means that cleaning cannot take place in the
vapor phase. Therefore, immersion tanks are
most commonly used for these applications in
conjunction with heat and agitation. Agitation
can be accomplished with ultrasonics or by
mechanically rotating the parts and/or circulating
the solution. Vapor degreasers and other solvent
cleaning processes can be modified to
accommodate water-based cleaners. Large
vapor degreasing units can be converted to
multiple tanks, and modified to incorporate spray
rinsing, immersion, ultrasonics, mechanical
agitation, filtration, or other methods.8
Immersion tanks that have a means for adequate
skimming of floating oils could be the most
useful aqueous/semi-aqueous method of cleaning
blind holes and complex geometries.
Aqueous Cleaning. Aqueous cleaning, or
parts washing, has been used for years to remove
salts, rust, scale, and other inorganic soils from
ferrous metals. As a potential substitute for
solvent vapor degreasing and CFC cleaning,
aqueous cleaning systems may require additives
to enhance their soil removal capabilities.9
Cleaned parts may also require rinsing to remove
residual cleaners and drying to prevent
corrosion. Some cleaning solutions also require
treatment before disposal.
Some additives of aqueous cleaning systems
include synthetic detergents and organic
surfactants, saponifiers, acids and alkalies, and
corrosion inhibitors. The combination of
additives selected alter the foaming, wetting, and
soil removal properties of the solution.10
Detergents and surfactants are surface-active
agents that emulsify insoluble solids into the
solution. Saponifiers change water-insoluble fats
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CHAPTER 9; MATERIALS AND PARTS DECREASING
and fatty acids into water-soluble soaps. Oxidants
may be added to loosen rust and stains for easy
removal. Other additives are used to penetrate
the soils and wet the surface of the materials to
be cleaned, to precipitate or float the soils, and to
neutralize the material. Depending on the
requirements of subsequent operations, rinsing
may be required to remove residual films left by
these additives in the cleaning process.11 Large
suppliers will typically formulate cleaners
designed for the particular soils to be cleaned and
the subsequent production process.
Aqueous cleaners must be carefully evaluated
for their compatibility with the materials being
cleaned and the cleaning equipment. Acid and
alkaline cleaners may attack some metal
substrates. Caustics or strong alkalies will
aggressively attack aluminum and zinc. Strong
acids will attack steel. Strong oxidizing acids
like nitric acid and chromic acid will attack
copper. The application of ultrasonics in an
aqueous system can also increase the
corrosiveness of the solution.12 In addition,
alkaline cleaning systems sometimes have
problems with surface oil recontamination of the
parts, rapid fluid depletion, long cleaning time,
and high maintenance.
Success has been observed by companies with
spray systems utilizing hot water solely as the
cleaning medium. Cutting oils, cooling fluids,
and other soils can be effectively removed by a
hot water spray. Many of the compatibility
problems with aqueous additives mentioned
above can be avoided by the use of a hot water
system, and wastewater treatment issues may be
simplified. Ease of operation can also be an
added benefit of a hot water spray system; the
oils arid greases separate more quickly from the
water phase (float to the water surface) than
would be observed with detergents or
surfactants. This allows for skimming of the oils
and grease and easy water recirculation.
Eliminating the need for monitoring and
adjusting the concentration of additives in the
aqueous solution can also free operator time for
other activities.
The treatment and disposal of the aqueous
cleaning solutions is an important consideration
when changing to an aqueous system. The use of
additives in the aqueous solutions cause many of
the disadvantages of these cleaning systems.
Some additives create new health and safety or
treatment and disposal issues. Detergents and
surfactants may not be readily biodegradable; the
solutions pH may be unacceptable for direct
discharge; cleaning solutions containing
saponifiers tend to have high biological oxygen
demands (BODs) which may exceed limits in
National Pollutant Discharge Elimination System
and POTW pretreatment permits. As a result,
pretreatment prior to discharge to the sewer
system may be required to meet local, state, or
federal requirements. As a response to these
disposal issues, "closed-loop" aqueous cleaning
systems have been developed which minimize the
process water that must be treated and
concentrate the oils and other contaminants for
disposal. These closed-loop systems can include
filtration (micro or ultra), gravity separation,
adsorption, and chemical treatment units which
recirculate the water back to the cleaning system
and concentrate the contaminants.13
Semi-Aqueous Cleaning. Semi-aqueous
cleaning processes use organic solvents, usually
in combinations with a surfactant, and in
combination with water. The semi-aqueous
solvents include terpenes, dibasic esters, glycol
ethers, and n-methyl pyrrolidone (NMP). In
semi-aqueous cleaning these solvents are utilized
in one of the following three applications: 1) as
emulsions in water; 2) in concentrated form,
followed by water rinsing; or 3) a combination of
these two applications.
Because these chemicals represent another
group of organic solvents, issues similar to those
associated with chlorinated vapor degreasing
solvents must be considered. The excellent
solvency of these chemicals allows for the
effective removal of difficult soils such as heavy
oils, greases, tars, and waxes. The flammability
and photochemical reactivity must be considered
when designing the process (i.e., limited
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PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
applications using heat and atomized spraying
units). The low volatility of these chemicals
minimizes the potential for worker exposure but
also results in slow drying of the parts. A final
water rinse may be required to remove chemical
residuals.
Terpenes are citrus or pine-based
biodegradable hydrocarbon solvents extracted
from citrus peels or pine trees. Glycol ethers are
synthetic organic chemicals mainly produced by
the reactions of epoxides (ethylene oxide or
propylene oxide) with alcohols. Dibasic esters
and NMP are discussed in more detail in Chapter
11. Petroleum-based hydrocarbons, also
frequently used in semi-aqueous applications, are
not recommended in this report if they contain
33/50 aromatics. Some additives may also
create new health, safety, treatment, and disposal
issues. For example, some glycol ethers are
toxic. The toxicity of many terpenes is not well
defined. In additions, terpenes are not as easily
recycled because they chemically bond to the
soils they remove. However, most of the
solvents are readily incorporated into a closed-
loop recycling system; the water can often be
recovered for re-use, and the cleaner must be
disposed of, possibly as a hazardous waste. In
the electronics industry, terpenes have been
found to be an effective substitute for CFCs in
the removal of flux from printed circuit boards.14
As with aqueous cleaning systems, the
treatment and disposal of semi-aqueous
wastestreams, both chemical and water, must be
addressed when considering this alternative to
vapor degreasing. Pretreatment operations
similar to those employed in aqueous cleaning
still apply to these systems: filtration,
adsorption, gravity separators, and chemical
treatment. One problem may be encountered
when trying to separate the solvents from the
water in a timely fashion. This can result in a
contaminated recirculated water stream,
significant organic discharges, and a solvent
wastestream which is not easily recoverable.
Proper design of decanting tanks, adequate
allotment of process time, and the use of
"second-generation" solvent blends which
separate more quickly from the water can
alleviate this problem. The solvent wastestream
can either be disposed of, or treated by vacuum
distillation to recover the pure components. Fuel
blending of the solvent wastestream, recovering
the solvents' BTU values, is also a possibility.
Non-Aqueous Solvent Substitutes
Non-aqueous substitutes include hydrocarbon
blends, alcohols, ketones, and HCFCs. Non-
aqueous substitutes are limited drop-in substitutes
for existing cleaners. They often have health,
safety, and disposal issues associated with their
production, use, and disposal that are similar to
those of the halogenated solvents. Many of the
non-aqueous substitutes are regulated and some
may be phased out in the future.
Alcohols, ketones, and hydrocarbon solvents
are presently used in some industrial sectors
(e.g., manufacturing and repair) for cold
cleaning applications. The hydrocarbon solvents
are usually combined with a surfactant and rust
inhibitor. Hydrocarbon blends, alcohols, and
ketones are effective in removing soils such as
cutting oils, coolants, greases, and waxes. These
compounds can also be effectively recycled.
Disposal options generally involve incineration.
Several characteristics of these cleaners,
however, limit their drop-in applicability. All
have low flash points which restrict their use in
enclosed systems and vapor degreasers.
Spraying is also not an option because the small
droplets can ignite below the flash point of the
bulk fluid. Finally, these alternative cleaning
solvents exhibit slower drying times than
traditional solvents, thus requiring an added
drying step, and/or increased processing time.15
For other applications, such as replacing
DCM in special cleaning applications like wiping
or paint gun cleaning, combinations of NMP and
dibasic esters (DBE) are being used. NMP and
DBE are discussed in more detail in Chapter 11
which presents their use as substitute paint
strippers.
Three HCFCs developed to replace CFCs as
a cleaning agent, HCFC-141b, HCFC-123, and
HCFC-225, have had limited exposure to the
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CHAPTER 9; MATERIALS AND PARTS DECREASING
commercial market. The solvency powers of
these HCFCs are between those of CFC-113 and
1,1,1-trichloroethane, and their boiling points are
lower, thus having the potential to be drop-in
alternatives in the existing CFC equipment.
However, based on the results of toxicity testing,
the existing worker exposure standard for 123
has been lowered, and tests involving the isomers
of 225 may show some toxicity.16 All three
compounds have already come under phase-out
legislation by the year 2015 (except in refrigerant
applications).
Non-Liquid Technologies
Non-liquid technologies include media
blasting and supercritical carbon dioxide (CO2)
cleaning. Because these technologies clean parts
without using liquids, they produce less waste.
Until recently, however, blasting and
supercritical technologies have been limited to
sturdy parts. Equipment costs are relatively
expensive.
When the temperature and pressure of a
substance such as CO2 are raised above the
critical point, the result is a supercritical fluid
with unique properties. For CO2 the critical
point is at 31°C and 72.9 atm. Supercritical
fluids possess high diffusivity, low density and
viscosity, and powerful solvency properties, all
of which contribute to the fluid's effective
cleaning capabilities. By controlling the pressure
and temperature of the supercritical fluid (thus
controlling the solvency properties),
contaminants can be dissolved and cleaned from
the substrate. This technique is particularly
appropriate for the cleaning of intricate precision
parts, if they can withstand the extreme
temperatures and/or pressures. Supercritical
fluids, however, do not appear effective for
removing ionic contaminants and paniculate
materials.
Media blasting uses the abrasive and/or
fraction ing action of a propelled media to remove
the contaminants from the soiled part. The
technique of media blasting has been used for
years to remove corrosion products, heat scale,
and carbon deposits on metal parts. Two
examples of media blasting materials are solid
CO2 crystals or pellets and sodium bicarbonate.
The recent development of small, supercritical
CO2 crystals, called CO2 "snow," makes CO3
media blasting effective in removing light
organics and participates from more precise and
delicate metal surfaces. Carbon dioxide snow
blasting minimizes the potential for damage to
the part's surface, and minimizes the amount of
waste generated. Upon contact with the surface
and removal of the soils, the CO2 instantly
sublimes. Carbon dioxide blasting is not
effective for cleaning oil and grease, however,
and cannot effectively clean parts with crevices
or blind holes.17
Sodium bicarbonate media blasting is an
alternative media blasting technique which could
potentially remove oils and greases. This
technique uses an aqueous slurry of water and
sodium bicarbonate under high pressure to
remove soils. Tests are currently underway to
determine the applicability of this technology
beyond its current industrial applications.
Conclusions
Substantial progress has been made in the use
of safe substitutes for the toxic, 33/50
halogenated organic cleaning solvents. Examples
of industries that are switching to safe substitutes
range from the printed circuit board industry, to
the automotive parts industry, and portions of
DOE's Weapons Complex.18
Aqueous and semi-aqueous cleaners have the
broadest range of application as safe substitutes
for the 33/50 halogenated cleaning solvents.
Still, a number of disadvantages exist to using
aqueous and semi-aqueous cleaners in place of
halogenated solvents. In particular, some of the
solvent alternatives may be flammable,
corrosive, or have limited or no toxicity data. In
addition, switching to aqueous or semi-aqueous
cleaners and processes generally requires
additional equipment, multiple cleaning and
rinsing steps, and drying, depending on the
cleaning level currently being attained in vapor
degreasers and other solvent-based cleaning
processes. Substitutes typically require process
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PART H; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
and facility testing in order to determine
optimum cleaning chemistries and equipment.
Thus, more than one cleaning system may be
required to replace one solvent vapor degreaser.
One possible alternative to avoid these
problems associated with aqueous and semi-
aqueous cleaners is a no-clean technology.
Eliminating the cleaning process significantly
decreases the use of any potentially toxic
chemicals. Redefining cleanliness specifications,
eliminating a step which soils the part, or
changing the nature of the soil to eliminate the
need for cleaning are only some of the potential
ways to implement this alternative.
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CHAPTER 9; MATERIALS AND PARTS DECREASING
ENDNOTES
1 Survey of Trichloroethylene Emission Sources, US EPA, Pub. No. EPA-450/3-85-021, (Research
Triangle Park, NC, July 1985).
"Solvent Cleaning (Degreasing)," Center for Emissions Control, November 1992.
2 "Solvent Cleaning (Degreasing)," Center for Emissions Control, November 1992.
3 Survey of Trichloroethylene Emission Sources, US EPA, Pub. No. EPA-450/3-85-021, (Research
Triangle Park, NC, July 1985).
Survey of Perchloroethylene Emission Source, US EPA, (Research Triangle Park, NC, June
1985).
Survey ofMethylene Chloride Emission Sources, US EPA, Pub. No. EPA-450/3-85-015,
(Research Triangle Park, NC, June 1985).
4 Toxic Air Pollutant Emission Factors - A Compilation for Selected Air Toxic Compounds and
Sources, 2nd ed., US EPA, Pub. No. EPA-450/2-90-011, (Research Triangle Park, NC, October 1990),
p. 414-419.
5 "Chemical Profile: Trichloroethylene," Chemical Marketing Reporter, Februarys, 1992.
6 John A. Sayre, "Overview of Developments to Reduce Environmental Impact Due to Surface
Finishing and Cleaning Processes," Environmentally Conscious Manufacturing: Recent Advances,
(Albuquerque, New Mexico: Riotech of New Mexico, 1992).
7 "Solvent Cleaning (Degreasing)," Center for Emissions Control, November 1992.
8 Ibid.
9 Ibid.
10 "Aqueous Cleaners Challenge Chlorinated Solvents," Pollution Engineering, December 1991.
11 "Solvent Cleaning (Degreasing)," Center for Emissions Control, November 1992.
12 Ibid.
13 Ibid.
14 Liz Harriman, "The Search for Safe, Effective Solvent Substitutes," Professional Engineering
TURA Report, Vol. 2, No. 2, Spring 1992.
15 "Solvent Cleaning (Degreasing)," Center for Emissions Control, November 1992.
16 Ibid.
17 Ibid.
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
18 Ann C. Finklin and Gordon L. Hickle, "Materials Substitution at the Rocky Flats Plant," The
Environmental Challenge of the 1990s, (Washington: Environmental Protection Agency Pollution
Prevention Office, 1990).
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CHAPTER 10
DRY CLEANING
Dry cleaning is a process that uses a
nonaqueous organic solvent for removing soils,
stains, and oils from textile products, fabrics,
and garments. It is used primarily for cleaning
natural fibers and materials, such as silk, cotton,
wool, and leather, that experience shrinkage or
water damage from aqueous cleaning. Some
synthetic fabrics, such as rayon derived from
cellulose, are also dry cleaned.
This chapter describes the use of and
substitutes for the 33/50 halogenated organic
chemicjil tetrachloroethylene (PCE) as a dry
cleaning solvent. Both PCE and 1,1,1 -
trichloroethane (TCA, another 33/50 halogenated
organic chemical) are used in dry cleaning, but
TCA has only a small market share in this
application. TCA use is also declining because
of its planned phase-out as an ozone depleting
substance.
Dry cleaning is the single largest use of
PCE, one of the 33/50 halogenated organic
compounds. In recent years, providers of
professional garment care have begun to
reassess the traditional dry cleaning process to
identify safe, effective alternatives to PCE-based
processes.
INDUSTRY DESCRIPTION
The dry cleaning industry consists of an
industrial sector, a commercial sector, and coin
operated dry cleaners. In 1991, there were an
estimated 25,200 existing commercial and
industrial dry cleaning facilities throughout the
U.S., compared to approximately 1,600 coin
operated facilities.1 More recent estimates place
the number of commercial dry cleaning shops in
the U.S. at more than 34,000.2
Industrial dry cleaners are large dry cleaning
plants that typically rent uniforms, linens, or
similar items to businesses, industries, and
institutions. Industrial laundry facilities use both
dry cleaning and water-based cleaning
equipment. EPA projects that the use of dry
cleaning in industrial laundry facilities will
decline during the five year period from 1991 to
1996 because many of these facilities are
switching from the use of solvents to the use of
water and detergent.3
Industrial dry cleaners typically use transfer
machines where clothes are washed in one unit
and then transferred to a separate unit to be
dried. A typical industrial dry cleaning plant has
one dry cleaning system consisting of a 750
pound-per-load capacity washer/extractor and
three to six 80-pound-capacity dryers.
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Throughput for a typical facility averages
approximately one million pounds per year.4
Commercial dry cleaners are usually small
neighborhood dry cleaning facilities, which are
either independently owned or franchise shops.
PCE is used by almost 75 percent of the
commercial dry cleaning sector. Petroleum
blends are used by most of the remaining
commercial dry cleaners,5 with only about 50 dry
cleaning facilities known to use TCA.6
Commercial facilities employ either transfer
machines or dry-to-dry units, which wash and
dry the clothes in a single unit. The capacity of
transfer machines in the commercial sector
usually ranges from 35 to 100 pounds per load.
A typical commercial facility that uses transfer
machines has one dry cleaning system that
consists of a washer/extractor and dryer, with an
annual throughput of about 39,000 pounds.7 The
current available market of new dry cleaning
machines is comprised almost exclusively of dry-
to-dry machines with built-in refrigeration
controls.8
Coin operated cleaners are usually part of
neighborhood laundromats, which offer dry
cleaning on an over-the-counter basis or a self-
service basis. They provide low cost dry
cleaning but not pressing, spotting, or associated
services. PCE is used by almost 98 percent of
these facilities; petroleum cleaning solvents are
not used at coin operated facilities.9 Coin
operated dry cleaning shops use dry-to-dry units.
Machine capacities range from 8 to 25 pounds
per load. A typical installation has two or three
machines and an annual throughput of roughly
20,000 pounds.10 Currently, there is a negative
growth rate for coin operated facilities because
existing facilities are not being replaced.11
Quantity of PCE Used in Dry Cleaning
As shown on the chemical-use tree diagram
for the halogenated organic compounds (Figure
3.1), an estimated 50 percent of the PCE used in
the U.S. is used by the dry cleaning industry.12
At the 1991 demand rate, this equates to 125
million pounds per year. EPA estimated,
however, that existing dry cleaning facilities
emitted 185 million pounds of PCE in 1991.
This estimate suggests that dry cleaning accounts
for a larger proportion of the PCE used in 1991,
or that the demand for PCE in 1991 was higher
than estimated.
Price of PCE Used in Dry Cleaning
Solvent economics play an important part in
dry cleaning. The total cost of supplying a retail
plant, which includes solvent, other chemicals,
hangers and packaging materials, ranges from 9
to 11.5 percent of all costs.13 The price in
January of 1994 for the dry cleaning grade of
PCE was $0.28 per pound (tanks and delivered),
compared to $0.29 per pound for industrial grade
PCE.14
DESIRED PROPERTIES OF DRY
CLEANING SOLVENTS
Factors that are considered when selecting a
dry cleaning solvent include processing features,
garment compatibility, and safety and health
related issues. A dry cleaning solvent should
have a high affinity for greases and oils and a
low affinity for fabric dyes. The solvent must
not corrode the common metals used in dry
cleaning equipment, and be chemically and
thermally stable under the variety of conditions
experienced in the dry cleaning process. The
solvent should also be compatible with the
detergents and spotting chemicals used as
supplements. The solvent should be sufficiently
volatile to leave the garment free of odors after
drying and evaporate at a sufficiently low
temperature to protect the fabric from damage in
the drying process. A low boiling point is also
preferred to allow separation of the solvent from
contaminants and detergents during solvent
recovery by distillation.
A dry cleaning solvent should also be safe in
terms of human health and toxicity. Worker
exposure may occur from storage and handling
of the solvent, from process emissions, and from
fugitive emissions. Although PCE is
nonflammable, OSHA and some state and local
governments have moved to place controls on
PCE emissions from dry cleaning facilities
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CHAPTER 10: DRY CLEANING
because of concerns about its toxicity. In
addition, EPA recently issued rules that regulate
PCE emissions from dry cleaning facilities as a
hazardous air pollutant (HAP) under the Clean
Air Act Amendments of 1990. Nevertheless,
PCE dominates the world market for dry
cleaning solvents because it is the most
successful, nonflammable replacement for
petroleum blends.
DRY CLEANING PROCESS DESCRIPTION
The basic dry cleaning process is similar to
ordinary laundering processes, except that an
organic solvent is used in place of water. The
principal steps of the process are one or more
solvent-wash cycles, physical extraction of the
excess solvent using a spin cycle, and tumble
drying. The same steps are employed for both
transfer and dry-to-dry machines.
Prior to the solvent-wash cycle, professional
garment cleaners inspect garments for stains and
heavily soiled areas. These areas are spot
cleaned using additional chemicals, steam, and
scrubbing; TCA is a commonly used pre-spotting
chemical. Next, garments are sorted by color or
fabric, and evaluated to choose which washing
method to use, either laundering (aqueous
washing), dry cleaning (solvent washing), or
hand washing. After drying, garments are
finished by steaming, then pressing. Steaming is
also used to remove water soluble materials
remaining after the wash cycle and to kill
bacteria^
The action of the solvent on the garment
fibers removes solvent-soluble oils and greases
and the mechanical tumbling action removes
insoluble soils. Lower surface tension enables
the solvent to penetrate the fabric, which in turn
allows insoluble soils to be more easily removed
by the mechanical tumbling action. The solvent
is continuously filtered during the washing cycle
to remove the insoluble soils.
During the extraction step, most of the solvent
is removed from the garments, which are then
tumbled with heated air. The temperature of the
air and the length of the drying cycle are
determined by the solvent used and by the
garments' fabric and construction.
To partially recover and reuse the solvent, the
treatment of dry cleaning solvent by filtration,
distillation, and charging is performed at some
dry cleaning facilities. Filtration removes the
insoluble solids, called muck, from the used
solvents. Filters may also contain activated
carbon that removes dye residues. Solids are
removed from the filters daily, and solvent
contained in the muck is usually recovered by
distillation.
Distillation is used to remove the soluble,
nonvolatile residue which accumulates in the
solvent. Following distillation, the solvent is
"charged" by adding a small amount of water
and detergent to the solvent. The detergent,
usually added at concentrations of 0.50 to 1.25
percent by volume,15 helps remove water-
soluble stains and enables the system to carry
moisture above the solvent's usual water-
saturation point. Most of the dry cleaning
detergents used are anionic.
ENVIRONMENTAL RELEASES OF PCE
FROM DRY CLEANING
Environmental releases from the use of PCE
in the dry cleaning process occur from the
production of PCE through the dry cleaning
process and the final disposal of PCE residuals.
The following presents the environmental
releases from production and distribution of PCE
followed by the releases from the actual dry
cleaning process.
Environmental Releases from Production and
Distribution
Emissions from PCE production facilities
were obtained from the 1991 TRI data and
discussed in Chapter 3. Total environmental
releases and off-site transfers of PCE from
production facilities in 1991 were almost 800,000
pounds. Using a life cycle approach,
approximately 50 percent of these releases can
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be associated with the dry cleaning industry,
since 50 percent of the PCE produced in the
U.S. is consumed in dry cleaning.
Approximately 70 to 75 percent of the total
PCE produced is distributed through distribution
facilities; the remaining 25 to 30 percent is
generally sold directly to CFC producers.16
Distribution facilities are not required to report
their emissions in TRI, but in 1983 h was
estimated that 110,000 pounds of PCE were
emitted to the atmosphere from these facilities.17
Again, using a life cycle approach,
approximately 50 percent of the PCE emissions
from distribution facilities can be associated with
PCE distributed to dry cleaning facilities.
Specialty chemical plants sometimes prepare
product formulations containing PCE for use in
dry cleaning. These facilities are classified
under SIC 2842, and are required to report
emissions to TRI. The 1991 emissions of PCE
from these specialty chemical plants reported in
the TRI are shown in Table 10.1
In 1991, more than 20,000 pounds of PCE
were reported released from the specialty
chemical producers, primarily to air. These
release figures may also include emissions
from facilities that prepare other types of
specialty cleaning, polishing, and sanitation
formulations that use PCE, and are not used for
dry cleaning.
Environmental Releases from Dry Cleaning
Facilities
Air emissions of PCE from dry cleaning
plants occur from equipment vents, from
chemical and clothing transfer and handling, and
from leaks in the process equipment. Emissions
also occur from waste materials such as the
dryer and filter muck and spent filters from
carbon absorbers.
The most significant point of process-type
PCE emissions is the dryer vent, where residual
PCE or vapors are exhausted from the dryer
or dry-to-dry unit. PCE is also emitted from
the washer vent in transfer machines. Process-
type emissions are also associated with the
auxiliary equipment that is used to filter and
distill the dirt>' solvent. These emission points
include vented emissions from muck cookers,
oil cookers, and other distillation equipment.'
TABLE 10.1. RELEASES AND TRANSFERS OF PCE FROM SPECIALTY CLEANING
POLISHES AND SANITATION GOODS PRODUCERS (SIC
Release or Transfer (Ibs/
Water Release
Land Release
Underground Injection Release
TOTAL ON-SITE RET.FASRS
POTW Transfer
Other Off-She Transfer
TOTAL OFF-SITE TRANSFERS
Sources:
TRI, 1991
Correspondence from Hampshire Research Assoc. Inc
U.S., EPA, Office of Pollution Prevention and Tories, 33/50 Program Office
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CHAPTER 10: DRY CLEANING
Fugitive emissions account for approximately
50 percent of the PCE emissions from a dry
cleaning facility.18 These emission sources
include the following:
• evaporation that occurs during the transfer
and handling of clothing;
• leaks from pumps, valves, flanges, and seals;
• losses during solvent loading and unloading;
and
• evaporation of PCE from stored solid waste,
which includes spent filters and distillation
residue.
EPA recently published a final rule for the
National Emission Standard for Hazardous Air
Pollutant (NESHAP) that will regulate PCE
emissions from dry cleaning facilities. EPA
classifies all sources in the industrial dry cleaning
category as major sources. For the purposes of
the rule, a major source includes any source
emitting more than ten tons of PCE per year.
Sources in the commercial dry cleaning sector
may be major or area sources (i.e., sources
where potential emissions do not exceed ten tons
per year, considering controls). Sources in the
coin operated dry cleaning sector are exempt
from the standards. The standards require all
new and existing dry cleaning facilities that are
major sources of PCE to control emissions to the
level of maximum achievable control technology.
New and existing area sources must control PCE
emissions to the level achieved by generally
available control technologies. Table 10.2
summarizes the requirements of the PCE Dry
Cleaning NESHAP (58 FR 49354). Dry
cleaners had until June 20, 1994 to meet
reporting requirements of the PCE NESHAP (58
FR 66287).
In announcing the rule, EPA said that dry
cleaners doing less than $75,000 in business
annually will be exempt from some of its major
controls.19 EPA estimated that the NESHAP will
cut process vent emissions of PCE by about
7,300 tons per year and fugitive emissions by
about 28,400 tons per year .M
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
Recent studies have raised new concerns
about the potential for exposure to PCE from
dry cleaning facilities. Elevated concentrations
of PCE have been found in indoor air at dry
cleaning establishments and at apartments
situated above dry cleaning establishments.
Worker safety is a significant concern in the
dry cleaning industry. In January, 1989, OSHA
adopted a 25 ppm PEL for PCE to reduce the
health effects from worker exposure to PCE.
OSHA allowed a four year phase-in period for
complying with the PEL "by any reasonable
combination of engineering controls, work
practice, and personal protective equipment
effective September 1, 1989 through December
30, 1992. "21 After the transitional period,
OSHA requires the PEL to be achieved without
personal protective equipment.
PCE emissions from dry cleaning also
contribute to toxic air pollutants in the
environment. Low levels of PCE have been
detected in the atmosphere. Higher
concentrations have been detected in urban areas
that contain numerous dry cleaning point
sources. For example, the average distribution
of PCE in air in the northern hemisphere was 56
parts per trillion in 1978. Typical levels of PCE
in ambient air in urban or industrial areas range
from 0.3 to 1.5 parts per billion (ppb) and may
reach 10 ppb or higher.22
In Germany, a study was conducted to
evaluate PCE air pollution originating from coin
operated dry cleaning establishments. The study
found indoor air concentrations of PCE between
3.1 and 331 mg/m3 at the dry cleaning
185
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CHAPTER 10: DRY CLEANING
establishments. Air samples collected from a
private car, in which a freshly cleaned jacket had
been transported, contained 9.3 mg/m3 PCE two
minutes after the jacket was placed in the car,
and 20.4 mg/m3 after the car had been driven
and parked. The study also found concentrations
of PCE in butter in apartments over the dry
cleaning shops.23
Recently, a study of indoor air in apartments
situated above dry cleaning establishments was
conducted by the New York State Department of
Health. PCE levels ranged from 300 to 55,000
A
-------
alternatives include multiprocess wet cleaning,
nitrogen injection of petroleum solvent, oxygen
vacuum with petroleum solvent, supercritical
carbon dioxide, machine wet cleaning,
microwave drying, and ultrasonic agitation.
Multiprocess wet cleaning and machine wet
cleaning are two new methods that use water as
the primary cleaning solvent. The nitrogen
injection and oxygen injection methods seek to
reduce the flammability hazard of petroleum-
based methods by lowering the oxygen
concentration in the cleaning drum. These
alternative processes are not considered safe
substitutes within the context of this report since
they may result in the use and release of the
33/50 aromatics. Microwave drying and
ultrasonic agitation are two processes still under
development. Two of these potential alternative
cleaning processes, multiprocess wet cleaning
and a proposed ultrasonic agitation system, are
described below.
Multiprocess Wet Cleaning. Multiprocess
wet cleaning, as defined by EPA, is a series of
textile cleaning steps which include spotting and
wet cleaning, with predominantly water-based
cleaning solutions which are usually not
recovered for reuse.28 ECOCLEAN*
International, Inc. is a commercial vendor
and franchiser of a multiprocess wet cleaning
method that has been used commercially in the
United Kingdom for a number of years.
The ECOCLEAN* process assumes that
almost 80 percent of fabrics can be cleaned by
washing or wet cleaning. Washing is the
immersion of fabrics in water either by using a
washing machine or by hand. Wet cleaning
involves the localized application of water,
steam, and soap. According to the company
literature, fabrics that cannot be washed or wet
cleaned can still be adequately cleaned with the
ECOCLEAN* process.
The basic ECOCLEAN* process relies on
cold water-based soaps made from essential oils
hand spotting to remove oily stains, and steam to
clean bacteria. An anti-static conditioner is used
to penetrate the fabric and release insoluble soils.
The company literature compares the
ECOCLEAN* process for cleaning a man's suit
to the traditional dry cleaning method. The
comparison is shown in Table 10.3
The ECOCLEAN* process differs from
traditional dry cleaning in that it does not use
chlorinated solvents, it is more labor intensive
and it relies heavily on the skills of the spotter.'
The company claims that increased labor costs
are balanced by decreased solvent costs and
energy consumption. Equipment requirements
for the ECOCLEAN* process are similar to
those of the dry cleaning process, and extensive
modification of existing equipment is typically
not required to convert to the ECOCLEAN*
process.29 No information was available on the
TABLE 10.3 COMPARISON OF CLEANING METHODS
Inspect for stains
Hand spot as required
Tumble dry
Vacuum to remove insoluble soil
Reinspect for stains
Press with live steam
Source:
ECOCLEAN*
Inspect for stains
Hand spot as required
Dry Clean
Reinspect for stains
Press with live steam
188
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CHAPTER 10: DRY CLEANING
actual costs for converting a typical commercial
dry cleaning establishment to the ECOCLEAN®
system.
From the company's perspective, the main
barrier to the use of the ECOCLEAN* process is
public perception.30 People believe dry cleaning
is necessary to clean water-sensitive fabrics. In
addition, garment care labels in the U.S. are
only required to provide one recommended
method for cleaning a garment. Frequently, dry
cleaning is recommended when washing or wet
cleaning would be as effective since there is less
potential for damage with professional garment
care.
The EPA Design for the Environment (DfE)
Program, in collaboration with ECOCLEAN*
International, Inc., the International Fabricare
Institute, the Massachusetts Toxics Use
Reduction Institute, and the Neighborhood
Cleaners Association, recently conducted a cost
and performance comparison of conventional dry
cleaning and the ECOCLEAN* method of
multiprocess wet cleaning. The results of the
study showed that in certain situations, the
multiprocess wet cleaning process is technically
feasible and economically competitive with
conventional dry cleaning. The DfE Program
will evaluate the risks of the wet cleaning and
other alternative processes hi a Cleaner
Technologies Substitute Assessment (CTSA).
Ultrasonic Agitation. One proposed, but
undemonstrated alternative garment cleaning
system would use the ultrasonic agitation of
constrained clothing in an aqueous, continuous
flow process. The proposed system is based on
the following premises:
• water combined with surfactants, wetting
agents, and oxidizers is the preferred solvent
for cleaning clothes;
• ultrasound can be used to provide the agitation
of the traditional cleaning drum;
• constraining the garments will increase the
efficacy of the ultrasound by making garments
more closely resemble a solid surface thus
decreasing their potential to absorb energy;
• constraining the garments will preclude
shrinkage;
• since a press is defined as the position and
shape a fabric is in when moisture (usually
steam) is removed, constraining the garments
will result in a "pressed" look in the drying
stage; and
• a continuous flow, conveyorized system will
allow for more efficient processing than
current batch-style equipment.
Thus far, preliminary tests on the effects of
porous lateral constraint on shrinkage and the
garment finishing process (i.e., pressing) have
been conducted. Test results show that porous
lateral constraint can control shrinkage on certain
fabrics and can be used to impart a "pressed
look" to fabrics. The DOE's Kansas City facility
is collaborating with Garment Care on these
tests.
Since a growing percentage of new clothing is
home launderable, industry growth potential is
seen as slim to negative. Besides the
environmental advantages, a fundamental goal in
developing this alternative process is to make the
professional garment cleaning process more
efficient and economically competitive with
home laundering.31
Solvent Substitutes
There are only a limited number of organic
solvents currently used for dry cleaning. The
dry cleaning solvents with the largest market
shares are PCE and petroleum blends.
Chlorofluorocarbon-113 (CFC-113) and TCA
are also used to a lesser extent. Although they
are not considered a "safe" substitute in the
context of this report, petroleum blends were
evaluated as possible substitutes for PCE and
TCA. Much of the recent research in solvent
substitutes has been aimed at reducing the
flammability hazard of petroleum blends used in
dry cleaning. CFC-113 is not considered a
potential safe substitute since this chemical
causes ozone depletion and is being phased-out of
production.
189
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Petroleum Solvents. Petroleum solvents
such as Stoddard Solvent have a 10 to 12 percent
share of the dry cleaning market in North
America.32 A major use of petroleum solvents is
leather and suede cleaning. The relatively gentle
solvency of petroleum blends makes petroleum
solvents popular for a range of textile garments
as well. There are several barriers to the use of
petroleum solvents as safe substitutes for PCE,
however.
The primary barrier to using petroleum
blends in broad range dry cleaning application is
their flammability. Frequently, local insurance,
zoning, and safety considerations favor a solvent
substitute that is nonflammable. PCE was first
widely used as a safe substitute for petroleum
blends because it is nonflammable. The recently
introduced nitrogen injection and oxygen vacuum
dry cleaning equipment are designed to reduce
the flammability hazard of petroleum solvents by
limiting the availability of oxygen in the cleaning
drum. Another petroleum blend, called 140°F
Solvent, is similar to Stoddard Solvent, except it
is less flammable.
A second obstacle to using petroleum blends
is costly liability insurance requirements for
commercial facilities that store petroleum
products in underground storage tanks (UST).
EPA UST regulations require facilities that store
petroleum in USTs and have a throughput of
10,000 gallons per year or more to obtain $1
million of liability insurance. Facilities with a
throughput of less than 10,000 gallons per year
are required to obtain $500,000 of liability
insurance. One industry representative believes
that the typical commercial dry cleaning shop
owner would be unable to absorb this added cost
and remain cost-competitive.33
Third, petroleum blends are not "drop-in"
replacements for PCE. Switching a PCE-based
dry cleaning facility to a petroleum-based facility
would require equipment modifications,
particularly in the distillation equipment. Many
acilities that use PCE have recently modified or
replaced their existing PCE-based equipment in
an effort to meet the OSHA PEL for PCE. An
industry representative suggested that anything
that affects the availability or price of PCE, or
requires additional equipment modification would
be a major blow to the industry because of the
money recently invested in new equipment or
equipment modifications.34
Finally, petroleum blends contain toxic
chemicals. Data on the potential for exposure
and health effects of exposure to petroleum
blends would be required to determine if use of
these chemicals results in less risk to workers or
others. The EPA Office of Pollution Prevention
and Toxics (OPPT) through its DfE Program is
collaborating with industry to develop a CTSA
for the dry cleaning industry. The CTSA will
examine the trade-offs in risk, performance, and
cost of alterative solvents or professional
cleaning processes that can be used in place of
the traditional dry cleaning process.
Other Substitute Solvents. Producers of
CFCs were making efforts to identify other
solvents, such as HCFCs, that could be
substituted for CFC-113, but one industry contact
was unaware of any large scale effort to find a
substitute for PCE. The efforts to find a
substitute for CFC-113 reportedly have been
terminated, possibly due to the relatively small
amount of this solvent that the dry cleaning
industry uses.35
At least one firm that manufactures so-called
"environmentally friendly products" has
advertised an environmentally safe, all natural
alternative to dry cleaning.36 The manufacturer
claims that the product is a blend of non-toxic
natural plant oils that Removes light soil and
odors, but not stains. The manufacturer claims
that the plant oils work by breaking the bonds
between the clothing and the soil and odors. The
soil and odors are encapsulated by the natural
plant oils, which are then vented through the
dryer.
Consumers use the product by spraying it
directly onto lightly soiled or odor laden clothing
and drying them in the home dryer for two
minutes. The Material Safety Data Sheet
(MSDS) for the product indicates that it contains
190
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CHAPTER 10: DRY CLEANING
no hazardous ingredients and has no flashpoint.
No attempt was made to evaluate the efficacy of
this product.
Conclusions
After decades of using a well established and
accepted batch process of cleaning clothes with
solvents, substantial progress has been made
recently in reevaluating the dry cleaning process
to identity technically and economically feasible
safe subsititute processes. It appears, however,
that little or no efforts are underway to identify
safe chemical substitutes for PCE in the
traditional dry cleaning process, and this study
was unable to identify any existing safe
substitutes. The most promising course to
eliminate or significantly reduce the use of PCE
for this application appears to be the use of more
washable fabrics, or the adoption of an
alternative cleaning process. Recent efforts by
the industry to meet EPA and OSHA regulations,
however, have probably made the industry
sensitive to changes that would require more
capital investment. More research is needed to
develop and demonstrate some of the proposed
alternative processes.
191
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PART H: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENDNOTES
1 Federal Register, US EPA, December 9, 1991, p. 64383-64386.
Federal Register, US EPA, December 9, 1991, p. 643X3-64386.
' (Research
Ibid.
Federal Register, US EPA, December 9, 1991, p. 64388.
8 Federal Register, US EPA, December 9, 1991, p. 64387.
^c^!^ Endssion Sources' us EPA' Office of Air **»• (Research
10 Ibid.
11 Federal Register, US EPA, December 9, 1991, p. 64383.
12 "Chemical Profile: Perchloroethylene, " Chemical Marketing Reporter, January 20, 1992.
Vol. A9
Vol. A9.
!3 Ullrmm'5Encycl°Pedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
14 Chemical Marketing Reporter, January 28, 1994.
." Ulltmm>sEncycl°Pedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
ssion Sourcest us EPA' °ffice
17 Ibid.
18 Federal Register, US EPA, December 9, 1991, p. 64389.
Environmental Reporter, September 17, 1993.
20 Environmental Reporter, September 24, 1993.
192
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CHAPTER 10: DRY CLEANING
21 Federal Register, US Occupational Safety and Health Administration, January 19, 1989,
p. 2670.
22 ..
Tetrachloroethylene," Hazardous Substances Data Bank, October 23, 1990.
23 Holger Gulyas and Lutz Hemmerling, "Tetrachloroethane Air Pollution Originating From Coin
Operated Dry Cleaning Establishments," Technical University of Hamburg-Hamburg, Germany,
Environmental Research, October 1990.
24 "An Investigation of Indoor Air Contamination in Residences Above Dry Cleaners," Risk
Analysis, New York State Department of Health, Albany, 1993, Vol. 13.
25 Conversation with David Porter, Garment Care, April 27, 1994.
26 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A9.
27 Federal Register, US EPA, December 9, 1991, p. 64386.
28 Multiprocess Wet Cleaning: Cost and Performance Comparison of Conventional Dry Cleaning
and An Alternative Process, US EPA, Pub. No. 744-R-93-004, .Office of Pollution Prevention and Toxics,
September 1993.
29 Subject: Clothes Care Alternative to Chlorinated Solvent Dry Cleaning, ECOCLEAN®,
(London).
30 Conversation with Robert Simon, ECOCLEAN®, May 22, 1992.
31 Conversation with David Porter, Garment Care, April 27, 1994.
Fast Laundry, November 12, 1993.
32 Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., (Weinham: VCH Verlag., 1985),
Vol. A9.
33 Conversation with Mohammed Kamara, International Fabricate Institute, May 26, 1992.
34 Conversation with Dr. Jerry Harlan, ADCO, May 26, 1992.
35
Ibid.
36 Environmentally-Safe All Natural Dry Cleaning Alternative Introduced fr> Natural World: Dry
Clean in Your Dryer, Natural World, Inc., (Stanford).
193
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CHAPTER 11
PAINT STRIPPING
Chemical paint stripping formulations that
include the 33/50 chemical dichloromethane
(DCM) are widely used by industry and the
public to remove paints and coatings from a
substrate. This use of DCM is of particular
concern because it can result in both consumer
exposure and worker exposure to this toxic 33/50
chemical. Recently, several safe substitutes for
DCM-based paint strippers have been developed.
This chapter describes the use of and substitutes
for DCM.
PRODUCT PROFILE
Paint strippers are used in both industrial and
consumer applications. Industrial applications
include the manufacturing of automobiles, of
metal and wood furniture, and the maintenance
of aircraft and military equipment. In the
consumer market, paint strippers are primarily
used to strip off old paint or varnish from
household products such as furniture.
Paint strippers are classified as application
strippers or immersion strippers. Application
strippers commonly have a solvent base and are
usually applied by brushing or spraying directly
onto the substrate. Common for small consumer
jobs, these paint strippers are also used in
industrial applications.
Immersion strippers are used primarily in
industrial applications to strip numerous items
simultaneously. Immersion types use either
solvent-based or aqueous baths. Solvent-based
baths, also called cold baths, are the most widely
used by industry. Aqueous paint strippers, also
called hot baths, include caustic or acid products.
Caustic strippers, the most widely used of the
aqueous paint strippers, are operated at
temperatures ranging from 82 to 116°C. They
contain caustic soda as the primary paint
stripping agent, chelating agents, and up to 20
percent organic solvents.1
The use of DCM-based paint strippers can
result in both consumer and worker exposure to
this toxic 33/50 chemical. Health and safety
concerns have helped spawn the development of
a number of safer substitutes for DCM-bu\ed
products.
195
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PART D: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
Although caustic cold baths may contain a
small fraction of DCM in their formulation, they
are not the focus of the substitutes assessments
presented here. Instead, this chapter focuses on
the use of and substitutes for cold bath
immersion strippers and application strippers that
use DCM as the key ingredient.
Quantity of DCM Used in Paint Stripping
About 124 million pounds, or 31 percent of
the total annual consumption of DCM, was used
for paint stripping in 1991.2 Of this total, 40
percent is used in industrial applications such as
periodic maintenance of commercial and military
airplanes, automobiles, and other equipment.
Another 40 percent is used in consumer
applications for the stripping of old finishes from
furniture and other wood. The remaining 20
percent is used for cleaning and reworking in the
manufacturing of automobiles and other
industrial goods. Approximately two-thirds of
the DCM used in the consumer market is used
directly by a home hobbyist. The other one-third
is used in the commercial submarket, where a
contractor performs the coating removal job.3
Price of DCM Used in Paint Stripping
In January, 1994, the price for large volumes
of industrial grade DCM was $0.29 per pound.
In April, 1994, prices of DCM-based paint
stripping formulations prepared for the consumer
market and sold in the Knoxville, Tennessee area
ranged from about $13 to $20 per gallon (about
$2 to $3 per pound). The amount of coverage
provided by DCM-based paint strippers varies
from about 50 to 100 square feet per gallon.4
DESIRED PROPERTIES OF CHEMICAL
PAINT STRIPPERS
The selection of a paint stripper depends on
the substrate, type of coatings to be stripped,
available equipment, time and temperature
limitations, odor and flammability of the
stripper, and disposal requirements for the spent
stripper. The desired properties of paint
stripping formulations include low flammability,
water solubility, low molar volume, low surface
tension, and relatively low odor and low fumes.
-v Paint strippers should have low flammability
for safer application in potentially hazardous
locations such as the paint mix room and spray
booths.5 Water soluble solvents are easier to
rinse from the substrate. A low-molar-volume
paint stripper allows fast and efficient solvent
penetration of the cured paint or coating. Low
surface tension allows the solvent to quickly
cover the entire surface being stripped and
allows immediate penetration of the paint film.
A paint stripping solvent with relatively low odor
and low fumes reduces the chance of respiratory
problems or asphyxiation.6
DCM-based paint strippers have found wide
acceptance because of their effectiveness and
efficiency, their applicability to a wide variety of
substrates and coatings, and their relatively low
cost. DCM is nonflammable and nonexplosive
when mixed with air. It is also the fastest of the
chlorinated solvents in lifting paint film.7
PROCESS DESCRIPTIONS
DCM-based paint strippers may contain a
number of components. The following sections
present typical composition ranges for DCM-
based strippers and the process for
manufacturing them; the paint stripping method
used during consumer applications; and solvent-
based industrial paint stripping methods.
Manufacturing of DCM-Based Paint Strippers
Components of a DCM-based stripper may
include co-solvents, activators, corrosion
inhibitors, evaporation retarders, thickeners,
emulsifiers, and wetting agents. Each of these
components provides particular functions. Co-
solvents, usually alcohols, esters, glycol ethers,
aromatic solvents, or ketones, are added to the'
196
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CHAPTER 11: PAINT STRIPPING
formulation to increase the versatility of the
remover in attacking coatings. Activators,
such as ammonia, amines, and formic acid,
are included to increase the rate of stripping.
Evaporation retarders, such as paraffin wax,
are used to form a film on the surface and
slow evaporation. A cellulosic thickener
may be added to hold the stripper on vertical
surfaces.
DCM-based paint strippers are formulated by
mixing the components according to a
predetermined order of addition. Mild heat is
sometimes used to dissolve paraffin wax if it is
used as an evaporation retarder.
DCM-based paint strippers formulated for
consumer use may be classified according to
their flammability. Nonflammable paint
strippers contain 75 percent or more of DCM,
and 5 to 15 percent of methanol, ethanol,
isopropanol, or a combination of the three.
Flammable DCM-based paint strippers contain
about 15 to 20 percent of DCM, 20 to 25 percent
of methanol, 35 to 40 percent of toluene or
mineral spirits, and 20 to 25 percent of acetone.8
Tj'pical composition ranges for DCM-based
strippers are listed in Table 11.1. The
concentration of DCM in existing paint strippers
may vary significantly, particularly in the
consumer market.
Consumer or Household Paint Stripping
Furniture stripping accounts for about 85
percent of the consumer use of paint strippers.9
The method for stripping off old paint with
chemical strippers requires very little equipment.
The paint stripper is brushed or sprayed in one
direction onto the surface, two square feet at a
time. The resulting sludge is removed by gently
scraping with a dull putty knife. After the sludge
is removed, residue is wiped away with mineral
spirits or some other solvent.
Industrial Paint Stripping
Industrial paint stripping methods are used in
OEM and maintenance services. In OEM
industries, paint strippers are required to
perform the following: 1) strip defective
manufactured goods before repainting; 2) clean
overspray from painting equipment like spray
booths, hooks, hangers, and racks; and 3) purge
paint lines and spray guns.
In maintenance services, paint stripping plays
an important role in repainting commercial
automobiles and aircraft. Here, the paint
stripper is either sprayed or brushed onto the
surface of the vehicle, or the parts are immersed
into a cold bath containing DCM. After the
solvent softens the paint, it is removed by
mechanical scraping.
TABLE 11.1 COMPOSITION OF NONFLAMMABLE DCM-BASED PAINT STRIPPERS
Component
Percent by Weight
Alcohol (e.g., Methanol, Ethanol or Isopropanol)
Amine (e.g., Dimethylethanolamine)
DCM
Hy
-------
PART II: PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENVIRONMENTAL RELEASES OF DCM
FROM PAINT STRIPPING
Environmental releases from the use of DCM
in paint stripping formulations occur from the
production of DCM through the paint stripping
process and the final disposal of DCM residuals.
The following sections present the environmental
releases from production and distribution of
DCM, followed by the releases from the actual
stripping process.
Environmental Releases from Production and
Distribution of DCM
Emissions from DCM production facilities
reported in the 1991 TRI were discussed in
Chapter 3. Total environmental releases and off-
site transfers of DCM from production facilities
in 1991 were 0.93 million pounds. Using the
principles of life cycle assessment, if 31 percent
of the DCM produced in the U.S. is consumed in
paint stripping formulations, approximately 31
percent of these releases can be associated with
DCM produced for this use. Similarly, some of
the DCM emissions from distribution facilities
are associated with DCM distributed to
manufacturers of paint stripping formulations.
Almost all of the DCM produced is
distributed through distribution facilities.
Distribution facilities are not required to report
their emissions in the TRI, but in 1983 it was
estimated that more than one million pounds of
DCM were emitted to the atmosphere from these
facilities.10
Environmental Releases of DCM from Paint
Stripping
Environmental releases of DCM that are
directly associated with the paint stripping
industry include releases from manufacturers of
DCM-based paint strippers and releases from the
actual paint stripping process.
Companies that manufacture paint stripping
formulations are classified under the SIC code
number 2851 (paints and allied products
manufacturers) and are required to report
emissions in TRI. The emissions of DCM for
SIC 2851 reported in the 1991 TRI are shown in
Table 11.2. Almost 600,000 pounds of DCM
were reported released from paints and allied
products manufacturers in 1991. Most of these
releases (59 percent) were emitted on-site to the
air. The remaining 41 percent was transferred
off-site to POTW or treatment, storage, and
disposal facilities. These release figures may
also include emissions from facilities that prepare
other types of paints and allied products that use
DCM.
EPA emission factors for the paint stripping
process range from a low of 400 pounds per ton
of DCM contained in the stripper formulation to
a high of 2,000 pounds per ton of DCM (100
percent loss to the atmosphere). The lower
emission factor is for dip tanks at durable good
manufacturers with emissions controlled by a
water seal and a 15 second drain time. The
higher emission factor applies to uncontrolled
emissions from floor stripping, furniture
stripping, and other general sources.11
EPA estimates that all of the DCM used in
consumer-oriented paint stripping products is
released to the atmosphere. Consumer
exposure to DCM via inhalation may result in
acute or chronic health effects.
HEALTH, SAFETY, AND
ENVIRONMENTAL ISSUES
The main exposure to DCM from paint
stripping occurs from inhalation. The health
effects of acute inhalation exposure discussed in
Chapter 3 include CNS depression and elevated
carboxyhemoglobin levels in the blood. The
consumer use of DCM-based paint strippers can
result in elevated carboxyhemoglobin levels that
could stress the cardiovascular system to
intolerable levels in a person with a diseased
CNS. DCM was considered the primary agent
responsible for the death of a 13 year-old boy
who was using a DCM paint remover.12
198
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CHAPTER 11: PAINT STRIPPING
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199
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSFSSMFNmz
EPA has assigned DCM a B2 carcinogenicity
rating based on positive evidence of
carcinogenicity in animal studies.
Because of these health concerns, OSHA has
proposed lowering the permitted average hourly
industrial exposure to DCM from 500 ppm to 25
ppm.13 Monitoring data suggest that the mean
time-weighted average personal exposure to
DCM in the workplace may be 100 to 200 ppm
or higher during paint stripping operations.14
Industry believes that the OSHA proposal could
accelerate declines in some segments of the
DCM market, particularly in paint stripping
applications.15 Still, consumers using DCM-
based paint strippers are afforded little protection
beyond warning labels on the product container.
EVALUATION OF SAFE SUBSTITUTES
FOR DCM PAINT STRIPPERS
In recent years, several alternatives to DCM-
based paint stripping formulations have been
developed. In the industrial sector, these
include:
• alternative paint stripping methods, such as
media blasting technologies;
• alternative chemical formulations that do not
use DCM; and
• product or process modifications that reduce
or eliminate the need for paint stripping.
In the consumer sector, safe substitutes for
DCM-based paint strippers are primarily
alternative chemical formulations that attempt to
use less toxic chemicals.
The substitutes assessments in this chapter
focus on the use of media blasting technologies
and process modifications in the industrial sector,
and the use of alternative chemical formulations '
in the consumer market. Except for economic
data, most of the information on alternative
chemical formulations is also applicable to the
industrial sector.
Media Blasting Technologies
Several paint stripping methods are available
that involve blasting the substrate with dry or
liquid media. These methods, characterized as
dry blasting or wet blasting, are usually used to
remove paint from airplanes and other vehicles.
In wet blasting, a liquid media is used (e.g., high
pressure water spray, crystalline ice, and sodium
bicarbonate), whereas dry blasting employs soft
plastic, wheat-starch, or carbon dioxide dry ice
as the blasting media.
Bicarbonate Media Blasting. The
bicarbonate media blasting method is a low
impact blasting technology and a safe, cost-
effective alternative. This process utilizes low-
pressure blasting equipment with a specially
formulated abrasive media based on sodium
bicarbonate. Bicarbonate media blasting can be
used in airplane maintenance, industrial
equipment maintenance, and OEM industries.
Sodium bicarbonate, more commonly called
baking soda, is water soluble, nonflammable,
nonexplosive, nonsparking, and nontoxic. The
sodium bicarbonate-based blasting system is
capable of removing paint as well as grease and
oil. The method is applicable to virtually any
substrate, particularly thin skinned metal and
composite substrate.
Industrial users of DCM-based paint
strippers can substitute alternative paint
stripping formulations or methods; or they can
modify their products or processes to reduce or
eliminate the need for paint stripping.
Currently, the most viable option for consumers
is to use alternative chemical formulations.
Bicarbonate media blasting involves
propelling the media by compressed air onto the
surface to be cleaned. The media strikes the
surface and disintegrates, taking with it the
coating. High pressure water is injected to
reduce the dust generated. The spent media is
not reusable for paint stripping but may be used
in a waste treatment facility to increase the
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alkalinity of other wastestreams. However,
some contaminants of waste paint are hazardous
to humans and the environment. Proper
treatment of wastewater, therefore, is essential
prior to disposal.
One of the disadvantages of this method is
that sodium bicarbonate may revert to caustic
soda ash in the presence of water and heat. The
hydrophilic nature of the soda ash can result in
the absorption of small amounts of moisture from
the air, which could cause corrosion problems.
Reportedly, it would be difficult to protect an
airplane from bicarbonate media intrusion.
Thus, the Federal Aviation Administration
(FAA) has not approved bicarbonate media
blasting for stripping aircraft. The total stripping
cost for this method has been estimated at $3.51
per square foot.16
Plastic Media Blasting. The plastic media
blasting method of dry paint stripping utilizes a
manufactured soft plastic media. Urea is the
most widely used resin in plastic media blasting,
accounting for 60 percent of the market in 1992.
Other materials used include melamine, acrylic,
clear-cut or polyester, although polyester is
rarely used today because it's stripping action is
too slow. The raw stock for most plastic media
is scrap molded parts, but some media
manufacturers also buy virgin molding
compounds and mold plates specifically for
plastic media blasting.17 After use, plastic media
can be recycled, cleaned, and regraded to virgin
media standard.
Plastic media blasting requires precision
control of media flow rates, particle ejection
velocity, and air pressure. Equipment
requirements include a blasting machine and an
air compressor for a supply of clean, dry
compressed air. The abrasive plastic beads are
forced at high velocity through a nozzle at the
painted surface; the resulting impact dislodges
the paint.
W;iste is generated by the dislodged paint and
the breakdown of the plastic beads. Therefore, a
dust collecting and separating system is required.
The separated waste paint is treated prior to
disposal. This dry paint stripping method has the
benefit of producing less wastewater.
Problems associated with plastic media
blasting include pitting or warping of the
substrate, low cutting rate, high media
breakdown rate, dust, and static. Plastic media
blasting is not believed to have universal
application for aerospace coating removal
because the process is too aggressive for
aluminum and composite surfaces.18
Many of the problems with plastic media
blasting have been associated with the materials
used to manufacture the media or the grinding
and classifying process. For example, scrap
molded parts used to make blasting media may
have been scrapped because of poor cure in the
molding process; excessive flash (partially cured
material on finished moldings at the junction of
the upper and lower molds) on the moldings; or
they contain contaminants. Blasting media made
from such scrap parts can be too soft or of
inconsistent quality. Blasting media made from
virgin materials, however, can also be made
from source materials of variable quality, leading
to similar problems of inconsistent quality.19
Despite these potential problems, the method has
been successfully used in a number of operations
and is approved by the FAA.20
The U.S. Navy has compared the process
costs for chemical paint stripping and plastic
media stripping of aircraft. Included in the cost
figures are material cost (chemicals or plastic
media), labor cost, utility costs, waste treatment
and disposal costs, and equipment maintenance
costs. Even without considering indirect costs
such as reduced liability cost, the Navy estimated
that plastic media blasting would save about 49
percent of the cost of chemical paint stripping,
from $25,898 per plane for chemical stripping to
$13,316 per plane for plastic media stripping.21
Starch-Based Media Blasting. The starch-
based media blasting method employs a dry blast
media manufactured from high quality wheat
starch in crystalline form. The wheat starch
product does not contain toxic chemicals and is
nonexplosive. Starch-based media blasting is
used to remove coatings in the aerospace
industry, particularly polyurethane and epoxy
paints from aluminum and composite surfaces.
In addition, it is capable of removing paint in
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other industrial applications, such as equipment
and mold cleaning.
Disposal of the waste generated in this method
depends on the toxicity of the coatings. In small
scale operations, the spent dust generated from
the dry-blasting media is removed from the work
area by a cyclone device.
Negative qualities of starch-based media
blasting include slower paint stripping rates than
with plastic media, and high cost. Starch
moisturization presents another problem; once
the starch is wet, it will no longer be effective
for stripping, even if dried. As a result, a clean,
dry air supply for the blast stream and measuring
equipment is recommended to prevent the
accumulation of moisture. The total stripping
cost for this method has been estimated at $1.87
per square foot.22
Starch-based media blasting is reportedly able
to strip a wide range of coatings from graphite,
fiberglass, and Kevlar without the risk of damage
to the substrate associated with plastic media
blasting. Commercial airlines are now using
wheat starch blasting to remove polyurethane
paints from thin clad aluminum in selected
applications. The U.S. military is also
reportedly evaluating wheat starch as a blasting
«• *>i ^»
media.
Other Media Blasting Technologies. Other
media-blasting methods include carbon dioxide
dry ice blasting, high-pressure water blasting,
and crystalline ice blasting. Carbon dioxide dry
ice can be used as a blasting media, but, like
sodium bicarbonate media blasting, is not
approved by the FAA for airplane maintenance.
Negative qualities of carbon dioxide dry ice
include its low productivity and its possible
contribution to global warming, albeit small.
High pressure water blasting may be
employed on some substrates, but is ineffective
against polyurethane coatings without first
applying a chemical stripper. The high-pressure
water blast may also pose a danger to workers,
and treatment of the process water is required
before being released to the sewer.
Crystalline ice blasting has been evaluated by
the FAA. It does not remove aerospace
coatings. Furthermore, this ice blasting method
requires refrigeration, ice-making, and ice-
handling equipment as well as protection from
excessive noise ""
24
Chemical Substitutes
Safe chemical substitutes are the most viable
alternative for the consumer market since they do
not require costly equipment. A number of
chemicals have been proposed or used as
substitutes for DCM in paint strippers. These
include NMP, DBEs, paint thinners, and other
solvents (e.g., alkyl acetate, diacetone alcohol,
and glycol ethers). Generally, chemical
substitutes have not been proven as effective in
paint stripping as DCM, especially on aged
paint. Also, the toxicity of chemical substitutes
may not be well documented.
As the solvents most frequently used in
alternative paint strippers formulated for the
consumer market, this section focuses on NMP
and DBEs and their relative performance, cost,
and environmental attributes as compared to
DCM. It should be noted, however, that
products containing these solvents and advertised
as safe may contain other toxic chemicals, such
as petroleum hydrocarbons. Researchers in
Denmark have found that chemical products
containing petroleum fractions may contain trace
levels of benzene. They measured the benzene
content in paint strippers and other chemical
products in which petroleum fractions are used
as ingredients and found benzene concentrations
of4to748ppm.25
Frequently, consumers cannot identify all of a
product's toxic ingredients from the product
label. For example, the MSDS from one
product that contains NMP and a DBE indicates
that the product also contains 8 to 15 percent
mixed petroleum hydrocarbons. The only
chemical ingredients listed on the label are
"esters of nonbasic acids" (DBEs).
DBE-based paint strippers formulated for the
consumer market cost approximately $20 per
gallon; NMP-based paint strippers are about $35
per gallon. Coverage for non-DCM
formulations is generally 15 to 25 square feet per
gallon as compared to 50 to 100 square feet for
DCM products.26 DCM-based paint strippers
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only remove one layer of paint at a time, where
the non-DCM formulations can strip multiple
layers in one application.
N-Methyl Pyrrol id one. NMP is an
acetylene-based solvent with lower density than
DCM. It is produced by the reaction of
butyrolactone with methylamine or from the
high-pressure synthesis of acetylene and
formaldehyde.27 Manufacturers of NMP include
ARCO Chemical Company in Channelview,
Texas; BASF Corporation, Chemical Division in
Geismar, Louisiana; and GAP Building
Materials, a subsidiary of International Specialty
Products, Inc. in Calvert City, Kentucky and
Texas City, Texas.28 Annual production volume
exceeds 55 million pounds. EPA estimates that
approximately 2.7 million consumers and more
than 71,000 workers may be exposed to NMP.29
Releases and transfers of NMP were not
required to be reported in the 1991 TRI.
Besides its use in paint stripping formulations,
NMP is used as a pigment dispersant, in
petroleum processing, as a chemical
intermediate, and as a spinning agent for
polyvinyl chloride. NMP is used in
pharmaceutical applications to enhance the
penetration and transfer of substances through
the skin. It has also been approved as a solvent
for slimicide application to food packaging
materials.30
NMP-based paint strippers are generally
formulated at lower solvent concentrations (20 to
40 percent), although the concentration of NMP
may r;mge from 12 to 80 percent. NMP is a
larger molecule than DCM and has lower vapor
pressure, lower volatility, and higher surface
tension. Thus, NMP-based strippers act slower
than DCM-based paint strippers. They can
dissolve multiple paint layers, however, which
allows less solvent to be used. NMP paint
strippers have a higher safety margin for
inhalation than DCM. At 20°C, the equilibrium
vapor concentration of NMP is 300 ppm,
compared to 450,000 ppm for DCM.31
NMP-based formulas are also applicable in
OEM. NMP can strip acrylic latex gloss
enamel, household epoxy spray paint,
polyurethane gloss enamel, high gloss wood
finish, and tallow oil alkyd spray paint. The
concentration of NMP in a paint stripper depends
on the application and type of coating to be
stripped. In the consumer market, the NMP-
based paint strippers have a high concentration of
NMP.32
EPA recently completed a study to evaluate
the use of an NMP-based paint stripping
formulation as a substitute for a DCM-based
product. The study was conducted at Tooele
Army Depot on a cleaning line designed for
depainting, cleaning, and applying conversion
coatings to nonferrous engine parts and
powertrain subassemblies. The NMP product
also contained monoethanolamine as a co-
solvent. Preliminary results of the study indicate
that NMP worked well, but took a little longer
than DCM to strip paint. The study also found
that NMP was less expensive than DCM and
could be used as a drop-in replacement in
existing equipment. This would allow the facility
to achieve substantial savings by making the
switch from DCM to NMP.33
EPA OPPT recently completed a study of
NMP, Life Cycle Analysis and Pollution
Prevention Assessment for NMP in Paint
Stripping. The study is a detailed evaluation of
consumer uses of NMP and estimates or
characterizes releases, exposures, and risk from
the use of NMP in paint strippers. The study
also evaluates risk reduction technologies. EPA
OPPT is also working with the Consumer
Product Safety Commission to perform an
assessment of the various chemicals used in paint
stripping products.34
In January, 1992, EPA placed NMP into a
risk management evaluation after an initial
review of data received from industry revealed
potential mutagenicity, developmental and
reproductive toxicity effects of NMP. In April,
1992, EPA informed NMP manufacturers that it
was concerned that exposure to NMP may
potentially result in adverse health effects on
reproduction and development. In November,
1993 EPA signed an Enforceable Consent
Agreement pursuant to the Toxic Substances
Control Act with ARCO, BASF, and
International Specialty Products to perform
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certain health effects tests with NMP. Required
tests include pharmokinetics, subchronic toxicity,
functional observation, motor activity,
neuropathology, and oncogenicity. The
deadlines for final reporting of test results range
from 6 months from the effective date for the 28
day subchronic toxicity range finding study to 72
months from the effective date for oncogenicity.
Dibasic Esters. DBEs are refined dimethyl
esters of adipic (dimethyl adipate), glutaric
(dimethyl glutarate), and succinic acids (dimethyl
succinate). Dimethyl adipate is synthesized by
the esterification of adipic acid with methanol in
the presence of an acid catalyst.35 Dimethyl
glutarate is produced by the esterification of
methanol with glutaric acid.36 Dimethyl
succinate is made by the direct esterification of
succinic acid with methyl alcohol in a
benzene/sulfuric acid solution.37
Each of these DBEs use petroleum
hydrocarbons or benzene somewhere in their
chemical synthesis pathway. For example,
adipic acid is made via oxidation of cyclohexane
in two processing steps.38 Cyclohexane is a
petroleum product and is obtained by the
distillation of petroleum, by hydrogenation of
benzene, or from toluene by simultaneous
dealkylation and double-bond hydrogenation.39
Glutaric acid is manufactured by the oxidation of
cyclopentanone with nitric acid.40
Cyclopentanone is prepared by heating adipic
acid.41
DBEs possess excellent solvent properties.
They are stable, low-cost liquids with high
boiling points. Their effectiveness can be
enhanced by blending them with other solvents
such as NMP. A base blend of 70 to 80 percent
of DBE and 20 to 30 percent of NMP is capable
of stripping a wide range of paints.42 One
disadvantage of this chemical is that the DBE-
based paint stripper takes two or three times
longer than DCM products to perform equivalent
stripping. However, DBE-based paint strippers
are able to remove a variety of coatings,
including acrylic latex enamel, epoxy,
nitrocellulose lacquer, and polyurethane
varnish.43 DBEs provide low emissions because
of their low volatility. An occupational limit of
1.5 ppm is recommended by the manufacturer.
Only limited data are available to evaluate the
toxicity of DBEs. As a result, the Consumer
Product Safety Commission recently sent a letter
of inquiry to the National Toxicology Program
regarding possible toxicity testing of DBEs.44
Process Modifications
Chemical paint strippers are used in OEM to
strip paint from defective manufactured parts
before repainting, clean overspray from paint
spray booths, and clean process lines and spray
guns used to deliver the paint to the spray booth.
Many manufacturers are finding that simple
product or process modifications can be made to
eliminate or substantially reduce the amount of
chemicals used in paint stripping without loss of
quality or increased cost.
Product modifications involve revaluation of
the need for painting. Frequently parts are
painted for aesthetic reasons alone, when there is
no underlying technical criteria, such as
corrosion protection. Manufacturers of
automotive parts, for example, are finding that
consumers are not concerned if under-the-hood
parts are not painted if the only reason for
painting the part is aesthetic. Eliminating the
unnecessary painting step can include cost
savings on materials and equipment used in both
painting and paint stripping, and material
handling and disposal costs. In addition to other
cost savings, the elimination of the toxic
chemicals used in paints and paint stripping
provides improved working conditions and
numerous intangible benefits such as improved
consumer perception. The challenge for
manufacturers who want to eliminate
unnecessary painting processes can be to
convince their clients that painting may not be
necessary for consumer acceptance when the
only reason for painting is aesthetic.
Process modifications involve Devaluating the
method of delivery of paint to the substrate,
taking into consideration factors such as paint
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overspray and the influence of the paint delivery
method on clean up requirements. Switching
rom solvent-based spray paints to powder
coatings is an example of a process modification
to eliminate or reduce the use of chemical paint
strippers. As discussed in Chapter 8, the
overspray from powder coatings is easily cleaned
up before the thermosetting resins have cross-
linked in a curing oven. Thus, use of powder
coatings can eliminate the need to use chemical
paint strippers to clean overspray from paint
booths or to clean process lines or spray guns
used in the painting process. Some method of
paint removal is needed, however, to remove
cured jx)wder coatings from hooks or other
equipment used to hold parts in place as they
pass through the curing oven.
Conclusions
Several media blasting methods have been
developed that are safe, effective substitutes for
chemical paint stripping in the industrial sector.
These methods are less viable for the consumer,
since they typically require expensive equipment.
Of the media blasting methods described in this
report, the plastic and starch-based methods
appear to be gaining the most widespread
acceptance. Still, selecting between these
methods requires an evaluation of their
environmental trade-offs.
Plastic-media blasting employs synthetic
organic chemicals that may cause health and
environmental effects during their production,
but this method generates little potentially
hazardous wastewater during the paint stripping
process. Starch-based media blasting does
not use toxic chemicals to strip paint, but does
generate potentially hazardous wastewater.
An evaluation of the life cycles of these products
would be required to fully assess which product
is the best environmental alternative.
The less volatile alternative chemical
stripping formulations appear to offer an
environmentally better choice for the consumer
than DCM-based strippers, at least because
there is less potential for exposure to NMP and
DBE via inhalation. The toxicity of these
substitutes needs to be better defined, however,
to determine how safe they really are.
Many manufacturers are finding that simple
product or process modifications can reduce
or eliminate the need for paint stripping in
industrial applications. These include switching
to powder coatings to reduce paint clean-up
requirements and eliminating the painting process
altogether. Not only do these modifications
save time and money, they can lead to increased
worker satisfaction and improved consumer
perception.
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PART II; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
ENDNOTES
1 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division Office of Toxic
Substances, (Washington: GPO, February 12-13, 1991).
2 "Chemical Profile: Methylene Chloride," Chemical Marketing Reporter, March 2, 1992.
3 "Source Reduction of Chlorinated Solvents: Paint Removal," Source Reduction Research
Partnership, June 1990.
4 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division Office of Toxic
Substances, (Washington: GPO, February 12-13, 1991).
5 Ibid.
6 Ibid.
7 Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., (New York: John Wiley, 1978),
8 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division Office of Toxic
Substances, (Washington: GPO, February 12-13, 1991).
9
Ibid.
10 Survey of Methylene Chloride Emission Sources, US EPA, Office of Air Quality Pub No
EPA-450/3-85-015, (Research Triangle Park, NC, June 1985).
11 Toxic Air Pollutant Emission Factors - A Compilation For Selected Air Toxic Compounds and
Sources, US EPA, Office of Air Quality, 2nd ed., Pub. No. EPA-450/2-90-011, (Research Triangle Park
NC, October 1990).
12 "Methylene Chloride," Hazardous Substances Data Bank," October 10, 1992.
13 Chemical and Engineering News, Vol. 1, November 18, 1991.
14 "Methylene Chloride," Hazardous Substances Data Bank, October 10, 1992.
15 "Chemical Profile: Methylene Chloride," Chemical Marketing Reporter, March 2, 1992.
16 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division Office of
Toxic Substances, (Washington: GPO, February 12-13, 1991).
17 'Plastic Blasting Media Problem Determination," Metal Finishing, July 1992.
18 Ibid.
19 Ibid.
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CHAPTER 11: PAINT STRIPPING
20 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division, Office of
Toxic Substances, (Washington: GPO, February 12-13, 1991).
21 Ibid.
-Ibid.
23 "Plastic Blasting Media Problem Determination," Metal Finishing, July 1992.
24 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division, Office of
Toxic Substances, (Washington: GPO, February 12-13, 1991).
25 "Residues of Benzene in Chemical Products," Environmental Contamination and Toxicology
Bulletin, 1993.
26 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division, Office of
Toxic Substances, (Washington: GPO, February 12-13, 1991).
27 "N-Methyl Pyrrolidone," Hazardous Substances Data Bank, January 17, 1994.
28 7992 Directory of Chemical Producers, United States, SRI International.
29 Federal Register, US EPA, November 23, 1993.
30 "N-Methyl Pyrrolidone," Hazardous Substances Data Bank, January 17, 1994.
31 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division, Office of
Toxic Substances, (Washington: GPO, February 12-13, 1991).
32 Ibid.
33 Conversation with Johnny Springer, US EPA, March 17, 1994.
34 Conversation with Mary Dominiak, US EPA, March 17, 1994.
35 "Dimethyl Adipate," Hazardous Substances Data Bank, April 16, 1990.
36 "Dimethyl Glutarate," Hazardous Substances Data Bank, April 16, 1990.
37 "Dimethyl Succinate," Hazardous Substances Data Bank, April 16, 1990.
38 "Adipic Acid," Hazardous Substances Data Bank, April 16, 1990.
39 "Cyclohexane," Hazardous Substances Data Bank, April 18, 1990.
40 "Glutaric Acid," Hazardous Substances Data Bank, April 16, 1990.
41 Merck Index, llthed.
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PARTH; PRIORITY PRODUCTS AND SUBSTITUTES ASSESSMENTS
42 Reducing Risk in Paint Stripping, US EPA, Economics and Technology Division Office of
Toxic Substances, (Washington: GPO, February 12-13, 1991).
43 Ibid.
44 Conversation with Mary Dominiak, US EPA, April 22, 1994.
•U.S. GOVERNMENT PRINTING OFFICE: 1994-550-001/00208
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