United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
EPA/600/R-92/175
October 1992
vvEPA
Opportunities for Pollution
Prevention Research to
Support the 33/50 Program
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EPA/GOO/R-92/175
October 1992
OPPORTUNITIES FOR POLLUTION PREVENTION RESEARCH
TO SUPPORT THE 33/50 PROGRAM
by
Battelle
Columbus, Ohio 43210
Work Assignment 06
EPA Contract No. 68-CO-0003
EPA Project Officer
Paul M. Randall
Waste Minimization, Destruction
and Disposal Research Division
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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NOTICE
This review of research needs summarizes information collected from U.S.
Environmental Protection Agency programs, peer reviewed journals, industry
experts, vendor data, and other sources. A variety of potential candidate source
reduction and recovery/recycling methods are described. This document is
intended as advisory guidance in identifying research needs for reducing pollution.
Publication of this document does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use. Compliance with environmental and occupational safety
and health laws is the responsibility of each individual business and is not the
focus of this document.
This effort has been funded wholly or in part by the United States Environmental
Protection Agency under Contract No. 68-CO-0003, Work Assignment 06. It has
been subjected to the Agency's peer review and administrative review, and it has
been approved for publication as an EPA document.
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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 (EPA) is charged by Congress with
protecting the Nation's land, air, and water resources. Under a mandate of
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 the 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 reviews common industrial uses and emerging future approaches to
reducing waste of the chemical groups identified in the "33/50 Program." The
Branch is charged with defining, evaluating, and advancing the technology for
implementing the national pollution prevention program. It also provides technical
assistance to other sections of the Agency for the purpose of reducing or
eliminating pollution hazards.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
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ABSTRACT
The intent of this effort was to provide guidance information for the Pollution
Prevention Research Branch in planning its research program. This document
compiles information on'existing pollution prevention methods and identifies
research needs. It helps define areas for research to increase application of
existing methods and create new approaches for source reduction and recov-
ery/recycling of the 17 chemical groups targeted in the 33/50 Program. The
emphasis is on source reduction, but recovery/recycling methods are also
considered.
A functional approach is used to identify and organize research areas for each of
the 17 targeted chemical groups. The sources and production characteristics and
rates are briefly summarized. Then pollution prevention opportunities and
supporting research needs are discussed for the major industrial and consumer
applications of the targeted chemical groups. The opportunities and research
needs are presented in both narrative and tabular formats.
This report was submitted in partial fulfillment of Contract 68-CO-0003, Work
Assignment 06, under the sponsorship of the U.S. Environmental Protection
Agency. This report covers a period from September 1991 to February 1992, and
work was completed as of June 1992.
IV
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CONTENTS
Notice .. .. . ii
Foreword '. ; Hi
Abstract iv
Tables viii
Acknowledgments ix
1 Introduction 1
Background 1
Pollution Prevention Act of 1990 . 1
Source Reduction 1
What Is the 33/50 Program? 2
What Is Pollution Prevention? 3
Major 33/50 Program Goals 3
What Are the Target Chemicals? 3
The 33/50 Program Signals a New Approach 4
What Is EPA Asking Companies to Do? 4
How to Get More Information 5
Toxic Release Inventory Database 5
Objective 6
Potential Users of This Document 6
References for the Introduction 11
2 Cadmium Pollution Prevention Research Needs for the 33/50 Program 12
Sources and Production Characteristics and Rates 12
Pollution Prevention Opportunities and Supporting Research Needs 15
Electrical Applications . 15
Coating and Plating 15
Pigments . 16
Plastics and Synthetic Products 16
Alloys . 17
Catalysts 17
Other Uses 18
References for Cadmium 18
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3 Chromium and Nickel Pollution Prevention Research Needs for the
33/50 Program 19
Sources and Production Characteristics and Rates . 19
Pollution Prevention Opportunities and Supporting Research Needs 26
Plating for Hardness and Corrosion Resistance , . 26
Plating for Appearance 29
Surface Etching, Preparation, and Cleaning 30
Alloying , . . 31
Water Treatment Chemicals 31
Refractories '....-.... i.... 32
Catalysts 32
Wood Treatment and Preservation 32
Pigments and Oxides -.34
Battery Manufacture 35
Leather Tanning 35
References for Chromium and Nickel 36
4 Cyanide Pollution Prevention Research Needs for the 33/50 Program 38
Sources and Production Characteristics and Rates 38
Pollution Prevention Opportunities and Supporting Research Needs 39
Electroplating ; 39
Mining and Ore Processing 41
Primary Metals 41
Treatment Processes . 41
Chemical Intermediates and Polymers 44
References for Cyanide 44
5 Lead Pollution Prevention Research Needs for the 33/50 Program 46
i
Sources and Production Characteristics and Rates 46
Pollution Prevention Opportunities and Supporting Research Needs 51
Emissions from Primary Lead Smelting 51
Alloys 52
Storage Batteries 56
Catalysts 57
Electrical Components 58
Paints and Pigments 59
Plastics and Rubber .' 60
Ceramics and Glasses 61
Specialty Uses 61
References for Lead 63
VI
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6 Mercury Pollution Prevention Research Needs for the 33/50 Program ......... 66
Sources and Production Characteristics and Rates 66
Pollution Prevention Opportunities and Supporting Research Needs 70
Batteries 70
Catalysts -. . . . 71
Chlorine and Caustic Soda 72
Switching Devices and Control Instruments 72
Electrical Lamps 73
Fungicides '. 73
References for Mercury 74
7 Pollution Prevention Research Needs for Eleven TRI Organic
Chemical Groups 75
Sources and Production Characteristics and Rates 75
Pollution Prevention Opportunities and Supporting Research Needs 88
Paint Stripping 88
Solvent Gleaning/Degreasing 90
Solvent for Coatings . . . . 93
Dry Cleaning ................. . ;...... 94
Blending Components in Gasolines 95
Emissions from Petroleum Refining and Related Industries . . . 95
Emissions from Primary Metal Smelting and Refining 96
Solvents for Printing Processes 97
Solvents for Rubber and Miscellaneous Plastic Manufacturing 98
Chemical Manufacturing . . . 98
References for Eleven TRI Organic Chemical Groups ....". '. 99
VII
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TABLES
TABLE 1. PROPERTIES OF THE TRI TARGET CHEMICALS 7
TABLE 2. REPORTED RELEASES FOR EACH CHEMICAL BY
RELEASE/TRANSFER PATH 9
TABLE 3. RELEASES AND TRANSFERS OF THE TRI CHEMICALS
BY INDUSTRY • • • • • • • 10
TABLE 4. CADMIUM POLLUTION PREVENTION RESEARCH NEEDS 13
TABLE 5. CHROMIUM AND NICKEL POLLUTION PREVENTION
RESEARCH NEEDS 20
TABLE 6. CYANIDE POLLUTION PREVENTION RESEARCH NEEDS 40
TABLE 7. LEAD POLLUTION PREVENTION RESEARCH NEEDS 47
TABLE 8. MERCURY POLLUTION PREVENTION RESEARCH NEEDS . 68
TABLE 9. ELEVEN ORGANIC CHEMICALS POLLUTION PREVENTION
RESEARCH NEEDS I 79
VIII
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ACKNOWLEDGMENTS
This report was prepared under the direction and coordination of Paul Randall of
the U.S. Environmental Protection Agency, Office of Research and Development,
Risk Reduction Engineering Laboratory, Pollution Prevention Research Branch, in
Cincinnati, Ohio.
Contributions were also made by Harry Freeman, Ivars Licis, S. Garry Howell, and
Hugh Durham of the U.S. EPA's Office of Research and Development. Also,
contributions were made by David Hindin of the U.S, EPA's Office of Prevention,
Pesticides, and Toxic Substances; Robert Pojasek and David Allen of the
American institute of Pollution Prevention.
This report was compiled and prepared by Battelle (under Contract No. 68-CO-
0003, Work Assignment 06) under the direction of Bob Olfenbuttel for the U.S.
Environmental Protection Agency Office of Research and Development.
IX
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1 INTRODUCTION
BACKGROUND
Pollution Prevention Act of 1990
Prior to passage of the Pollution Prevention Act of 1990 (PPA) in November 1990,
U.S. environmental protection regulations generally focused on treatment and
disposal of polluting materials rather than reduction at the source. The PPA
established prevention of pollution at the source as a national policy.
1.
2.
3.
4.
Source Reduction
Industry is encouraged to prevent or reduce pollution at the
source wherever feasible.
Unpreventable pollution should be recycled in an environ-
mentally safe manner when feasible.
When pollutants cannot be prevented or recycled, they
should be treated.
As a last resort, pollutants would be disposed of or other-
wise released into the environment.
Source reduction, as defined by the Act, means any practice that
"reduces the amount of any hazardous substance, pollutant or
contaminant entering any waste stream or otherwise released into
the environment (including fugitive emissions) prior to recycling,
treatment or disposal: and which reduces the hazards to public
health and the environment associated with the release of such
substances, pollutants, or contaminants." (U.S. EPA, 1991 a)
The EPA is empowered by the PPA to establish a program for the EPA to promote
source reduction. According to the PPA, the EPA will:
1. Facilitate adoption of source reduction techniques by busi-
nesses and other federal agencies.
2. Establish standard methods for measuring source reduction.
3. Determine effect of regulations on source reduction.
4. Find opportunities to use federal procurement to encourage
source reduction.
5. Improve public access to data collected under federal
environmental statutes.
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INTRODUCTION
6. Implement a training program on source reduction opportu-
nities, model source reduction auditing procedures, a source
reduction clearinghouse, and an annual award program.
What Is the 33/50 Program?
The 33/50 Program is EPA's voluntary pollution prevention initiative to reduce
national pollution releases and off-site transfers of 17 toxic chemicals by 33% by
the end of 1992 and by 50% by the end of 1995. EPA is asking companies to
examine their own industrial processes to identify and implement cost-effective
pollution prevention practices for these chemicals. Company participation in the
33/50 Program is completely voluntary. The Program aims, through voluntary
pollution prevention activities, to reduce releases and off-site transfers of a
targeted set of 17 chemicals from a national total of 1.4 billion pounds in 1988 to
700 million pounds by 1995, a 50% overall reduction. The Toxics Release
Inventory (TRI) (established by federal law, the Emergency Planning and
Community Right-to-Know Act of 1986) will be used to track these reductions using
1988 data as a baseline. As required by the Pollution Prevention Act of 1990, TRI
industrial reporting requirements were to be expanded, beginning in calendar year
1991, to include information on pollution prevention.
EPA announced the 33/50 Program in February 1991 when EPA Administrator
William K. Reilly asked 600 U.S. companies to reduce their releases of these 17
toxic chemicals. EPA contacted these 600 companies first because TRI data
indicated that these companies were the largest dischargers to the environment
of these chemicals. EPA is also contacting thousands of additional companies that
release these 17 chemicals and requesting their voluntary participation in the 33/50
Program. All companies are encouraged to participate in the 33/50 Program (even
if they do not receive a letter from EPA inviting them to participate).
While EPA is seeking to reduce aggregate national environmental releases of
these 17 chemicals by 50% by 1995, individual companies are encouraged to
develop their own reduction goals to contribute to this national effort. EPA also
encourages companies to reduce releases of other TRI chemicals and to extend
these reductions to their facilities outside the United States. For those companies
that have not yet made a commitment to participate, EPA encourages them to
participate in this national pollution prevention initiative. EPA will periodically
recognize those companies that commit to reduce their releases and transfers of
the targeted chemicals, and will publicly recognize the pollution prevention success
companies achieve. (U.S. EPA, 1991b; U.S. EPA, 1992)
What Is Pollution Prevention?
The overall goal of the 33/50 Program is to promote the benefits of pollution
prevention while obtaining measurable reductions in pollution. Pollution prevention
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INTRODUCTION
is the use of materials, processes, or practices that reduce or eliminate the
creation of pollutants or wastes.
Pollution prevention should be considered the first step in a hierarchy of options
for reducing the generation of pollution. The next step in the hierarchy is responsi-
ble recycling of any wastes that cannot be reduced or eliminated at the source.
Wastes that cannot be recycled should be treated in accordance with environmen-
tal standards. Finally, any wastes that remain after treatment should be disposed
of safely. .
EPA is promoting pollution prevention because it is often the most cost-effective
option to reduce pollution, and the environmental and health risks associated with
pollution. Pollution prevention is often cost effective because it may reduce raw
material losses; reduce reliance on expensive "end-of-pipe" treatment technologies
and disposal practices; conserve energy, water, chemicals, and other inputs; and
reduce the potential liability associated with waste generation. Pollution prevention
is environmentally desirable for these very same reasons: pollution itself is reduced
at the source while resources are conserved.
Major 33/50 Program Goals
The 33/50 Program has three basic goals. First, EPA is aiming to reduce national
aggregate environmental releases of the 17 target chemicals from 1988 levels by
33% by the end of 1992 and by 50% by the end of 1995. Second, EPA is
encouraging companies to use pollution prevention practices (rather than end-of-
pipe treatment) to achieve these reductions. Third, EPA hopes that this Program
will help foster a pollution prevention ethic in American business whereby
companies routinely analyze all their operations to reduce or eliminate pollution
before it is created.
What Are the Target Chemicals?
The 17 chemical groups are:
Benzene
Cadmium & Cadmium Compounds
Carbon Tetrachloride
Chloroform
Chromium & Chromium Compounds
Cyanide & Cyanide Compounds
Lead & Lead Compounds
Mercury & Mercury Compounds
Methylene Chloride
Methyl Ethyl Ketone
Methyl Isobutyl Ketone
Nickel & Nickel Compounds
Tetrachloroethylene
Toluene
1,1,1-Trichloroethane
Trichloroethylene
Xylenes
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INTRODUCTION
These chemicals were selected from the Toxics Release Inventory (TRI). The TRI
is a computerized database containing public information on the annual releases
and transfers of approximately 300 toxic chemicals reported by U.S. manufacturing
facilities to EPA and the States. Since 1987 federal law has required facilities to
report the amount of both routine and accidental releases of the 300 listed
chemicals to the air, water, and soil, and the amount contained in wastes
transferred off-site.
The chemicals listed above were selected for the 33/50 Program because:
1. They are produced in large quantities and subsequently
released into the environment in large quantities.
2. They are generally identified as toxic or hazardous pollut-
ants; thus there may be significant environmental and health
benefits from reducing their releases to the environment.
3. The is the potential to reduce releases of these chemicals
through pollution prevention.
The 33/50 Program Signals a New Approach
The 33/50 Program complements EPA's traditional command and control
approach. The key attributes of this new approach are:
National in Scope. Success will be measured according to whether reductions
have been achieved nationwide, rather than for each company or facility. The
reductions also will be looked at as an aggregate — total releases of all chemicals
rather than for each one.
Voluntary. Companies are free to decide if and how to participate in the program
by: a) committing to meet their own specified reduction goals; and b) making good
faith voluntary efforts to identify and implement cost-effective prevention measures.
Any steps taken to reduce targeted toxics will not be enforceable, unless these
activities are otherwise required by law or regulation.
Multi-Media. The reduction goals apply to total releases and off-site transfers to
air, land, and water.
Prevention-Oriented. EPA's objective is to encourage these reductions through
pollution prevention. However, companies are encouraged to participate in the
33/50 Program even if all of their reductions are not achieved through prevention.
What Is EPA Asking Companies to Do?
EPA is contacting thousands of companies to provide them with information on the
33/50 Program and to solicit their participation. Each company is being asked to
examine its processes to identify and implement cost-effective pollution prevention
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INTRODUCTION
practices that will reduce or eliminate releases of the 17 chemicals. In addition,
companies are being asked to submit a letter to EPA publicly stating their
reduction goals and how they plan to achieve them. All companies wishing to
.participate in the 33/50 Program and receive official public recognition of their
(Commitments are encouraged to supply EPA with information on their reduction
goals. ,
How to Get More Information
Guidance on how a company can participate in the 33/50 Program is available
upon request. For copies of this commitment guidance and other 33/50 Program
documents, fax your request to the TSCA Assistance Service at (202) 554-5803.
For more information on the 33/50 Program, contact the TSCA Hotline at (202)
554-1404, (8:30 am.to 4:00 pm).
Information on pollution prevention (and the 33/50 Program) is available through
the Pollution Prevention Information Exchange System (PIES), a free computer
bulletin board associated with EPA's Pollution Prevention Information Clearing-
house. To learn how to use the Clearinghouse and the PIES, call (703) 821-4800.
To access the PIES using a PC, a modem, and communications software, call
(703) 506-1025 (set your communications software to no parity, 8 data bits, and
1 stop bit).
Toxic Release Inventory Database
The computerized Toxic Release Inventory (TRl) database was established to
track toxic releases by the Emergency Planning and Community Right-to-Know Act
of 1986. The TRl contains public information on the annual releases and transfers
of approximately 300 toxic chemical groups. US. manufacturing facilities report
on these chemical groups to the EPA and the states. The law requires reporting
of both routine and accidental releases of these 300 chemical groups to the air,
water, and soil, and the amount contained in wastes transferred to off-site
locations. The TRl includes the 17 chemical groups selected for the 33/50
. Program based on these reasons: ;
1. They are produced, and subsequently released, in large
quantities. Collectively, more than 6,000 parent companies
reported 1.4 billion pounds of releases or off-site transfers
of these 17 chemical groups in 1988.
2. Because they are generally identified as toxic or hazardous
pollutants, significant environmental and health benefits may
accrue from reducing their releases to the environment.
3. Their releases potentially may be reduced through pollution
prevention.
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INTRODUCTION
The PPA requires facilities that report releases for the TRI to report on pollution
prevention and recycling. Information would include quantity entering the waste
stream, percentage change from the previous year, source reduction practices,
and changes in production from the previous year.
The 17 priority chemical groups are listed in Table 1. The chemicals are chiefly
heavy metals, chlorinated organic compounds, and nonchlorinated solvents.
These high-priority chemicals are of the greatest concern to the EPA's air, water,
land, and toxic chemical control programs. The EPA sought a way to reduce their
serious known health and environmental effects and to limit their exposure.
To help focus the discussion of pollution prevention research needs for the 17
chemical groups, releases and transfers reported in the 1988 TRI data are
summarized in Tables 2 and 3. Table 2 shows the reported releases for each
chemical by release/transfer path. Table 3 details releases and transfers by
industry. The 50 industries, identified by the four-digit Standard Industrial Category
(SIC), for each chemical are grouped by two-digit SIC. All other four-digit SICs are
grouped as others.
OBJECTIVE
This document compiles information on existing and emerging source reduction
and recovery/recycling methods for each of the 17 priority chemicals targeted in
the 33/50 Program. It provides an overview of many common uses of the priority
chemicals and potential methods for reducing waste of the chemicals. Based on
these uses and waste reduction methods, research needs are identified. The
research needs describe functional requirements for research to expand the
application of existing methods or to foster rapid development of emerging
methods.
This document provides a preliminary review of a broad range of candidate
methods. It is intended to focus development and screening of new ideas and to
facilitate planning for research projects in source reduction and recovery/recycling.
Selection of research opportunities is concerned with the efficient allocation of
money, skills, equipment, and facilities to projects. Careful selection of projects
is essential to efficient use of limited resources. Research efforts should be
focused on projects that give a significant reduction of the target chemicals and
have a reasonable probability of success.
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INTRODUCTION
POTENTIAL USERS OF THIS DOCUMENT
This document broadly scopes the functional requirements of research needed to
develop source reduction methods for the priority chemicals. The document is
intended for those in charge of 33/50 Program application, for R&D and process
development personnel at companies where releases or off-site transfers of the 17
priority chemical groups take place, and for researchers and process development
personnel at other companies doing independent research on source reduction
technologies, and on recovery and recycling operations.
The purpose of this document is to present interesting and stimulating challenges
leading to new ideas for research in the development of new methods for source
reduction and recovery/recycling.
Although examples are used to clarify the discussion, the definition of research
needs describes the functions needed without reference to a specific approach.
Specifications of the research needs are, as much as possible, stated as functions
to avoid limiting creativity in developing new ideas. There is also an attempt to
make the statement of research needs sufficiently general to ensure the resulting
technologies have wide application and to avoid projects requiring a large
component of proprietary intellectual property.
REFERENCES FOR THE INTRODUCTION
Perry, J.H., and C.H. Chilton. 1963. Chemical Engineers' Handbook, 4th ed.,
McGraw-Hill, New York.
U.S. EPA. 1991 a. Pollution Prevention Act of 1990. Office of Pollution
Prevention, Washington, DC, March.
U.S. EPA. 1991b. The 33/50 Program: Forging an Alliance for Pollution
Prevention (2nd ed.). Special Projects Office, Office of Toxic Substances,
Washington, DC, July.
U.S. EPA. 1992. EPA's 33/50 Program Second Progress Report, JS-7Q2A, Office
of Pollution Prevention and Toxics, February.
Verschueren, K. 1983. Handbook of Environmental Data on Organic Chemicals,
2nd ed. Van Nostrand Reinhold, Co.
11
-------
2
CADMIUM POLLUTION PREVENTION RESEARCH NEEDS
FOR THE 33/50 PROGRAM
SOURCES AND PRODUCTION
CHARACTERISTICS AND RATES
Cadmium (chemical symbol Cd) is a Group II-B element in the Periodic Table and
exhibits a +11 oxidation state in almost all of its compounds. Pure cadmium
compounds are rarely found in nature, although occurrences of greenockite, CdS,
and otavite, CdCO3, are known. The main sources of cadmium are sulfide ores
of lead, zinc, and copper, from which cadmium is recovered as a by-product of
production of these ores. Because cadmium is produced as a by-product of
sulfide ore refining, reducing cadmium consumption may not directly affect
cadmium production rates. However, reducing cadmium use will avoid distribution
of cadmium throughout the environment and should, therefore, be pursued.
Cadmium is obtained in vapor form when roasting sulfide ores, and as a sludge
from zinc sulfate purification. Pure cadmium metal is silver-white, tinged with blue,
and lustrous. Cadmium is often converted to its oxide, CdO, where it is a more
convenient starting material for synthesis of other compounds.
Of the estimated 4,080 tons of cadmium consumption in 1990, the U.S. Bureau of
Mines (1991) has approximated apparent consumption patterns as follows:
batteries
coating and plating
pigments
plastics and synthetic products
alloys and other uses
40%
25%
13%
12%
10%'
Cadmium and its compounds are highly toxic. Most poisoning cases have been
reported to be due from inhalation of fumes or dusts. Fumes are formed at high
temperatures by such industrial processes as welding and brazing, and they may
be released from incinerators that are unequipped with pollution control devices.
Cadmium is immediately dangerous to human health upon exposure to 1 mg/m3
over an 8-h period (Chizikov, 1966) and is lethal in air concentrations of 6 mg/m3
over an 8-h period (Barrett and Card, 1947). Cadmium causes a range of
systemic effects, for example, kidney and lung damage. Some shellfish tend to
concentrate cadmium and it causes chronic effects in many aquatic organisms.
A variety of cadmium applications and potential approaches for reducing waste are
summarized in Table 4 and are outlined in the text following the table.
12
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ESEARCH NEEDS
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ICH NEEDS (Continued)
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CADMIUM
POLLUTION PREVENTION OPPORTUNITIES
AND SUPPORTING RESEARCH NEEDS
Electrical Applications
. Cadmium hydroxide is used as the active anode material in rechargeable silver-
cadmium and nickel-cadmium batteries. Silver-cadmium oxide material is used to
make electrical contacts, cadmium chalcogenide electroluminescent and
photoconductive devices, as well as phosphors and several types of semiconduc-
tors. Cadmium arsenides, antimonides, and phosphides are used in many
electronic devices and semiconductors. A minor use of cadmium sulfide is in the
manufacture of photovoltaic solar cells.
Replace cadmium hydroxide in Ag-Cd and
Ni-Cd batteries. Alternative materials may be
available for battery anodes.
Research needs. Research is needed to
determine the performance requirements for
rechargeable and high-performance batteries
and to identify test methods to measure perfor-
mance with respect to those standards. Then
candidate materials can be identified and
tested as alternatives.
Coating and Plating
Cadmium is used in plating because it has properties that are superior to those of
other coatings for some applications. It is used to plate fasteners to help ensure
that the parts pass torque-tolerance tests, which simulate the action of a power
wrench tightening a nut on a bolt. The nut should tighten quickly under the proper
applied torque and hold securely thereafter. Cadmium is a soft metal and has
natural lubricity, which give it good torque properties. It also has good corrosion
resistance and meets salt-spray tests used in the automotive industry. In the past,
numerous military specifications have required the use of cadmium.
The major cadmium complex used in electroplating is cadmium cyanide,
Cd(CN)4~2; other plating salts include cadmium sulfate, sulfamate, chloride,
fluoroborate, and pyrophosphate. Cadmium borates are used with a fluoroborate
process for electrodeposition of cadmium in high-strength steels. Cadmium oxide
is used in electroplating baths, dissolved in excess sodium cyanide. Cadmium
suifate is used in electrodeposition of cadmium.
Eliminate cyanide pollution from-cadmium
plating. Traditionally, most cadmium plating is
done using cyanide because of its excellent
throwing power. Other plating solutions are
being tried that do not contain cyanide and
offer high cathode efficiency at high current
Research needs. Research is needed to test
and evaluate the characteristics of cadmium
plating performed without cyanide.
15
-------
CADMIUM
density. These baths contain metallic salts
such as neutral sulfates, acid sulfates, and
acid fluoroborates. Non-cyanide baths are
often preferred for cadmium plating of
quenched and tempered high strength steels
because less hydrogen is generated, thus
lessening the danger of embrittlement. Ajax
Metal Processing in Detroit plates a large
number of parts using a proprietary non-cya-
nide method.
Use an alternative to cadmium plating, such
as ion vapor deposition (IVD) aluminum.
IVD aluminum has recently been used as a
substitute for cadmium plating in aircraft parts
because of its excellent corrosion resistance ;
and because it meets or exceeds most of
cadmium's performance features (Holmes et - •
al., 1989; Rizzietal., 1986).
Pigments
Cadmium sulfide, cadmium sulfoselenide, and lithopone pigments are used to
produce a range of colors, including yellow, orange, red, and maroon. These1 '
colorants are sometimes used in plastics, paints, rubber, paper, glass, inks, and
ceramic glazes, although pigment applications are being reduced.
Research needs. Research is needed to
verify that IVD aluminum can be used in place
of cadmium plating for commercial, applica-
tions. ;I
Use nonhazardous materials for pigment.
Alternative nonhazardous materials may be
available for coloration.
Minimize use of cadmium pigments. It may
be possible to reduce the amount of cadmium
compounds used on a coating material.
Plastics and Synthetic Products
Research needs. Research is needed to
determine the performance requirements for
cadmium pigments and to find alternative:
substances that are nonhazardous.
Research needs. Research is needed to
determine the performance requirements for
cadmium pigments and to find methods of
improving performance without adding more
cadmium pigment.
Organocadmium salts are used as heat and light stabilizers in some plastics,
particularly PVC, to retard discoloration. Cadmium salts of organic acids are used
together with barium soaps to produce stabilizers for plastics.
16
-------
CADMIUM
um in stabilizers would account for a large sav-
ings in cadmium usage.
that can be substituted for cadmium com-
pounds to prevent PVC and other polymers
from discoloring.
Alloys
Cadmium oxide is used in the manufacture of silver alloys.
Research needs. Research is needed to
examine the properties of pure metals and
alloys in order to determine if they may be
adapted for use in place of silver-alloys'. /
Research needs. Research is needed to
examine the properties of plastics and com-
posites in order to determine if they may be
adapted for use in place of silver-alloys.
Use a non-silver alloy. Non-silver alloys may
be used to fabricate products that do not spe-
cifically require silver's physical properties to
perform their functions.
Use a plastic or composite alternative.
Products that do not require silver's electrical
or physical properties to perform their functions
may be fabricated instead from plastic or
composite materials. Substitutions of this sort
may be possible in low-temperature applica-
tions, such as decorative cast materials.
Optimize traditional alloying operations. If
cadmium cannot be avoided, improvements
can be developed to reduce waste in tradition-
al operations.
Recover or recycle cadmium in alloying
process. Develop methods to remove impu-
rities in cadmium-alloys used for casting,
plating, or other processes, to extend lifetime
of the melt. For example, ion-specific separa-
tion methods may be needed to allow repro-
cessing.
Catalysts
Cadmium dialkyls and many inorganic cadmium salts are used as catalysts,
particularly for organic polymerization reactions. Cadmium carbonate is used as
a catalyst in the production of other cadmium compounds. Cadmium tungstate is
an industrial catalyst.
Research needs. Areas of need may exist to
decrease waste and improve recycling in
traditional processing operations.
Research needs. Research is needed to
improve the performance of separation, tech-
nology. Ion-specific techniques may be used
in this regard.
Change synthesis path to avoid the need of
a catalyst or use a nonhazardous catalyst.
Different combinations of chemical feedstocks
Research needs: Research is needed to
determine the requirements for specific reac-
tions and to identify test methods to measure
the purity, yield, and other requirements. Then
17
-------
CADMIUM
Different combinations of chemical feedstocks
may allow preparations of the desired product
without the need for a catalyst.
Other Uses
tions and to identify test methods to measure
the purity, yield, and other requirements. Then
candidate reaction paths can be identified and
tested as alternatives for paths requiring
cadmium compounds as catalysts.
Cadmium chloride is used in photography, dying and cloth printing, special mirrors,
and lubricants. Cadmium nitrate is used in photographic emulsions.
Eliminate cadmium from miscellaneous Research needs. Research is needed to fully
uses. Find alternative materials with similar understand the role of cadmium in these
performance features as cadmium for substitu- various uses in order to find viable alternatives,
tion into product or process.
REFERENCES FOR CADMIUM
Barrett, H.M., and B.Y. Card. 1947. J. Ind. Hyg. Toxicol.29: 286.
Chizikov, D.M. 1966. Cadmium, trans. D.E. Hayler, Pergamon Press, Oxford, p.
17.
Holmes, V.L, D.E. Muehlberger, and JJ. Reilly. 1989. The Substitution of IVD
Aluminum for Cadmium. U.S. Air Force, Final Report, ESL-TR-88-75,
Humphreys, P.G. 1989. "New Line Plates Non-Cyanide Cadmium." Products
Finishing, May, pp. 80-90.
Kirk, R., and D. Othmer (Eds.). 1979. Encyclopedia of Chemical Technology, 3rd
ed., Vol. 7, John Wiley & Sons, New York, NY.
Licis, Ivars J., Herbert S. Skovronek, and Marvin Drabkin. 1991. Industrial
Pollution Prevention Opportunities of the 1990s. EPA/600/8-91/052, Task 0-9,
Contract 68-C8-0062. Risk Reduction Engineering Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio, August.
Nelson, K.E., 1990. "Use These Ideas to Cut Waste." Hydrocarbon Processing.
March.
Rizzi, KW., NJ. Spiliotes, and K.F. Blurton. 1986. "New Zinc Electroplate Fights
Both Wear and Corrosion." Metal Progress, February, pp. 51-55.
U.S. Bureau of Mines. 1991. Mineral Commodity Summaries.
18
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CHROMIUM AND NICKEL POLLUTION PREVENTION RESEARCH NEEDS
FOR THE 33/50 PROGRAM
SOURCES AND PRODUCTION
CHARACTERISTICS AND RATES
Chromium is a naturally occurring hard, brittle, steel-gray metal. It is produced
from chromite ores. Chromium has a wide range of uses in three primary
consumption groups. The metal is a major constituent in stainless steel and other
specialty ferrous and nonferrous alloys. Of the 418,924 tons of chromium
ferroalloys, metal, and other chromium-containing metals used in 1988, stainless
steel accounted for 80% of the reported consumption. Manufacture of refractory
bricks to line metallurgical furnaces used 88,750 tons of chromite in 1988. The
chemical industry consumed chromite for manufacturing sodium bichromate,
chromic acid, and pigments (BOM Cr, 1988). Chromium chemicals, such as
chromic acid, are frequently used in metal plating applications.
Nickel is a naturally occurring malleable, silvery metal. Nickel ores occur mainly
as sulfides or oxides, with sulfides accounting for about two-thirds of the world's
supply. The reported consumption of nickel in 1988 was 195,758 tons. Nickel,
like chromium, is a major constituent of austenitic stainless steels. Stainless steel
accounted for 40% of the reported nickel consumption in 1988. Nonferrous and
superalloys accounted for another 31% of nickel consumption. Electroplating was
the next largest nickel use at 17% (BOM Ni, 1988). Nickel is also used as a
catalyst and in batteries, pigments, and specialty ceramics.
A variety of chromium and nickel applications and potential approaches for
reducing waste are summarized in Table 5 and are outlined in the text following
the table.
19
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CHROMIUM AND NICKEL
POLLUTION PFtEVENTION OPPORTUNITIES
AND SUPPORTING RESEARCH NEEDS
Plating for Hardness and Corrosion Resistance
Hard chromium plating is used to provide a working surface for a part. Chromium
plating is the standard method for improving the hardness; smoothness; chemical
inertness; or resistance to wear, abrasion, galling, or high temperatures for a wide
variety of substrates. Typical applications are cylinder liners and pistons for
internal combustion engines, cylinders and rams for hydraulic pistons, and
extrusion equipment in plastic making (Guffie, 1986). Hard chromium plating will
continue to be needed for specific applications, but alternatives are available for
many of chromium's traditional applications. Design engineers will be required to
be more selective in specifying hard chromium plating by exploring alternative
technologies.
The hard chromium plating is electrolytically applied onto the substrate from an
aqueous solution of chromic acid and sulfuric acid. The most common form of
chromium in the plating baths is hexavalent chromic acid. Chromium metal is
deposited on the substrate by a complex six-electron reduction of hexavalent
chromium. The reduction reaction is catalyzed by the sulfuric acid. Plating from
a hexavalent bath reliably produces a bright chromium plating. However, the
current efficiency, the quantity of chromium deposited per unit of electric energy
used, the throwing power, and the ability to produce a uniform coating over a large
area are low. Hydrogen produced by the plating operation can migrate into the
metal substrate and embrittle it. The use of hexavalent chromium involves
operator exposure to chromic acid — a toxic material — and requires treatment and
disposal of chromium waste.
The most commonly sought property for engineering nickel coatings is corrosion
resistance. However, nickel plating also provides wear resistance, solderability,
magnetism, and other properties needed in specific applications. Nickel plating is
applied to protect chemical, pulp and paper, and other similar process equipment
that must survive in corrosive environments. Nickel is frequently used as an
undercoat for chromium plating where the chromium provides a hard bright surface
and the nickel gives good corrosion resistance. Nickel plating is also used to
salvage worn, corroded, or incorrectly machined parts.
Nickel plating involves deposition of a layer of nickel on a substrate. During
deposition of nickel metal on the cathode, the nickel anode dissolves. Direct
current flows through a solution of nickel salts to drive the reaction. Nickel is
present in the solution as divalent ions that are converted to nickel metal at the
cathode. The nickel in the bath is replenished by dissolution of the anode, so
nickel plating can typically operate for long periods without interruption. Anode
efficiency for nickel plating is typically 100%, whereas the cathode efficiency is
26
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CHROMIUM AND NICKEL
slightly lower. As a result, the nickel concentration in the bath increases with use,
and periodic adjustments to the bath concentration are required. Chloride, sulfate,
sulfamate, and fluoroborate are the, most common nickel salts used in the plating
baths. Nickel coatings for engineering purposes are usually prepared from
solutions that deposit pure nickel.
Use an alternative substrate that does not
need chromium or nickel plating. It may be
possible to use an alternative substrate to
provide sufficient hardness or corrosion resis-
tance. For example, advanced ceramic and
composite materials have been tested as
replacements for metal parts in internal com-
bustion engines.
Use nonaqueous plating for chromium or
nickel pollution prevention. If an alternative
substrate is not available, it may be possible to
produce a coating with the necessary proper-
ties without plating from an aqueous bath.
Hard coatings can be applied by physical va-
por deposition (PVD). For example, titanium
nitride is used as a coating to improve the
wear resistance of cutting tools.
PVD coatings are applied in a vacuum cham-
ber. A cleaned piece of substrate material is
placed in a heated vacuum chamber. A gas
plasma or electric arc heats and vaporizes the
metal that is to be plated onto the substrate.
The vaporized metal ions are deposited onto
the substrate as a thin hard film (Gresham,
1991).
Plate with a less hazardous metal. Aqueous
electroplating with less hazardous metals is
another approach to reducing use of hard
chromium or nickel plating. The electroplating
operation is conceptually the same as chro-
mium or nickel plating but, of course, uses
different bath composition and plating condi-
tions such as voltage and current. Possible
alternatives include nickel-tungsten-silicon
Research needs. Research is needed to de-
termine the performance requirements for hard
chromium or nickel plating in specific applica-
tions and to identify test methods to measure
the performance with respect to those stan-
dards. Then candidate substrate materials can
be identified and tested as alternatives for hard
chromium or nickel plating in specific applica-
tions.
Research needs. PVD coatings are generally
harder and thinner than electrolytically deposit-
ed coatings. The major research need is to
develop PVD coatings that give the required
hardness and coiating thickness, as well as
other required performance characteristics,
uniformly over a large complex part.
Research needs. The major research need is
to develop replacements for chromium or
nickel that give the required hardness and
coating thickness, as well as other required
performance characteristics, at a reasonable
cost. Given the generally low current effi-
ciency, deposition rate, and throwing power of
hexavalent chromium plating, it is likely that
alternative plating systems will give similar or
better production rates.
27
-------
CHROMIUM AND NICKEL
carbide plating (Schiffelbein, 1991) and molyb-
denum plating (Groshart, 1989).
Replace hexavalent chromium with trivalent
chromium plating. There is a continuing
trend in the chromium plating industry toward
replacing hexavalent chromium baths with tri-
valent chromium baths, although trivalent
plating is used mainly for appearance coatings
rather than for hard coatings. The chromium
chemicals used in trivalent plating are more
expensive than those used in hexavalent
plating. Some of the higher cost can be offset
by the higher current efficiency and better
throwing power of the trivalent process, as well
as by selection of additives and process opti-
mization to reduce costs.
Another impediment to wider acceptance of
trivalent chromium is the color and finish
achieved. Trivalent chrome gives a "gray"
satin nickel appearance that is acceptable in
many applications. While appearance should
not be a major concern in most hardness and
corrosion resistance applications, many cus-
tomers prefer the "blue" finish typical of hard
chromium plating from a hexavalent bath.
The anodes in trivalent chromium baths must
be immersed in a non-chromium electrolyte
solution held in a semipermeable membrane
shield in the tank. The shielding prevents
formation of hexavalent chromium at the
anode. The shield occupies space in the bath
that could otherwise be used for plating
throughput (PsF, 1988).
Optimize traditional plating operations. If
nickel or hexavalent chromium cannot be
avoided, improvements can be developed to
reduce waste in traditional nickel or hexavalent
chromium plating operations (PsF, 1988).
Research needs. Research is needed to op-
timize trivalent chromium plating and expand
its range of application. The major area of
concern is to develop trivalent chromium
plating methods that produce a coating with
similar thickness, hardness, and color to
hexavalent chromium plating. Methods to opti-
mize the trivalent plating bath composition and
operation to reduce costs are needed. Im-
proved designs to minimize the volume re-
quired for electrode shielding are needed.
Research needs. Areas for research leading
to improved plating operations include (1.)
using conductivity controls to minimize rinsing
water use, (2) studying bath viscosity/temper-
ature relations to optimize rates for solution
draining from parts, and (3) studying the
mixing effects to optimize plating tank agita-
tion.
28
-------
CHROMIUM AND NICKEL
Recover or recycle plating solutions and
rinse baths. Plating paths can be processed
for reuse to decrease waste. Traditional
separation processes can be used to recycle
rinsing solutions or other baths that are no
longer usable because of dilution but are not
contaminated with undesirable impurities.
However, the concentration or pH of the solu-
tions may lead to challenges in equipment
design or operation. If the solution is contami-
nated with impurities, more advanced ion-
specific separation methods are needed to
allow reprocessing.
Plating for Appearance
Research needs. To expand the use of cur-
rent separation methods such as evaporation,
reverse osmosis, or ion exchange for process-
ing spent plating solutions, research is needed
to improve performance with high-salt-con-
centration, low-pH solutions (Walker et al.,
1990).
To extend the useful life of contaminated plat-
ing solutions, new ion-specific separation
methods need to be developed. Advanced
selective ion separation methods to consider
include advanced ion exchange resins, crown
ethers, or membranes.
Chromium plating is applied in some cases mainly to improve the appearance of
the part. The plating solutions and procedures for appearance plating are similar
to those for hard chromium plating. However, the operating conditions such as
plating current and voltage are different.
Like chromium, some nickel plating has a mainly decorative function. Nickel
plating appears on many commonly used items such as pins, paper clips, scissors,
keys, and fasteners. Solutions used for appearance nickel plating have
compositions similar to baths used for functional plating. However, baths used for
appearance plating contain organic agents to modify the growth of the coating to
control the surface finish of the nickel deposit.
Similar pollution prevention and recovery/recycling options are available for
appearance plating. For example, plated parts could be replaced by brushed
aluminum parts to eliminate the need for plating, a less hazardous metal could be
applied to reduce the potential for pollution, or refractive plastics coatings could be
used to eliminate metal plating. Because the appearance plating baths are similar,
optimization and the bath recovery and recycling approaches for functional
chromium and nickel plating will also apply. Appearance chromium and nickel
coatings have lower wear resistance, corrosion protection, and thermal resistance
requirements, so additional options are available for chromium and nickel replace-
ment in appearance applications.
Use a non-chromium or non-nickel appear-
ance coating. Because of the reduced perfor-
mance requirements for appearance coatings,
organic coatings such as refractive plastic or
powder coatings can be acceptable.
Research needs. Research is needed to de-
termine the performance requirements for
appearance chromium or nickel plating in
specific applications and to identify test meth-
ods to measure the performance with respect
29
-------
CHROMIUM AND NICKEL
to those standards. Then candidate coatings
can be identified and tested as alternatives for
appearance chromium or nickel plating in spe-
cific applications.
Surface Etching, Preparation, and Cleaning
Hexavalent chromium in the form of chromic acid is an inexpensive but powerful
oxidizing solution. The oxidizing power of chromic acid solutions leads to a wide
variety of industrial applications for cleaning and preparing surfaces.
Chromic acid deoxidizing/desmutting — chromic acid is
used to remove the natural metal oxide and other surface
contaminants to prepare a surface for plating, painting, or
other surface treatment.
Chromic acid etch — chromic acid roughens surfaces to
improve coating adhesion.
Chromic acid anodize — anodizing is a process for treating
aluminum to give a highly corrosion-resistant coating that
offers an excellent surface for bonding and painting.
Anodizing uses electrochemical methods to form a thin
aluminum oxide surface layer that contains chromium ions.
Sealing — Sodium dichromate as a sealant enhances
fatigue properties by anodizing and by depositing
oxydichromate onto the anodized layers.
Chemical film — chromate solutions can be used to
chemically deposit a thin film to prepare metal surfaces for
subsequent painting (Evanoff, 1990).
Use alternative etchant for silicon wafer
testing. Chromic acid is used to etch silicon
wafers to reveal flaws in the crystal structure.
The silicon wafers are the starting material for
semiconductor circuits, so minute flaws must
be reliably detected. Alternatives to chromic
acid etching solutions are being developed and
tested (Dickens and Cannon, 1991).
Use alternative oxidizing agents to prepare
metal surfaces for coating or other use.
Chromate solutions are used in a wide variety
Research needs. Research is needed to ide-
ntify solutions that will provide adequate etch-
ing speed, give sufficient etching to meet or
exceed current flaw detection requirements,
and be compatible with the final use of the
silicon wafer.
Research needs. Surface preparation alterna-
tive methods to treatment with hexavalent
chromium need to be developed. The alterna-
30
-------
of surface cleaning and pretreating processes.
Several different formulations have been tested
as alternatives to chromate solutions for sur-
face preparation in a specific application
{Bibber, 1991; Carrillo et ai., 1991; Stewart,
1991).
CHROMIUM AND NICKEL
lives must provide a surface layer with corro-
sion resistance, paint adhesion properties,
impact resistance, and other anodic coating
properties equal to those provided by chromate
treatments.
Alloying
Chromium and nickel are common alloying additions in both nonferrous alloys such
as chromium in Stellite™ or nickel in Inconel™ and in ferrous alloys such as
chrome and stainless steels. The addition of chromium and/or nickel increases the
corrosion resistance and durability of the alloys.
Use non-chromium, non-nickel metal alloy
or use a nonmetal alternative. It may be
possible to develop other alloying agents to
give the required wear, heat, or corrosion
resistance. In lower temperature applications,
it may be possible to use plastic or composite
materials to replace chromium or nickel alloys.
However, considerable effort by the nuclear
industry searching for a replacement for Stel-
lite™ has met with limited success. The
manufacture of plastics and composites may
generate organic solvent waste.
Increase recycle of high performance al-
loys. High alloy steels and superalloys are not
are readily recycled as mild steels. The alloy-
ing agents essentially become impurities in the
steel making process when the alloys are
recycled. It may be possible by increasing
waste segregation and/or operating in smaller
batches to increase the recycle of high per-
formance alloys.
Water Treatment Chemicals
Research needs. Research is needed to de-
termine the performance requirements for
alloys in specific applications and to identify
test methods to measure the performance with
respect to those standards. Then candidates
can be identified and tested as alternatives for
chromium and nickel alloys in specific appli-
cations.
Research needs. Research is needed to de-
termine the performance requirements for
recycled alloys in specific applications and to
identify test methods to measure the perfor-
mance with respect to those standards. Then
candidates can be identified and tested as
alternatives for chromium and nickel alloys in
specific applications.
Chromate salts, in combination with phosphate salts or other chemicals, are very
effective for control of corrosion in low- and medium-temperature cooling water
systems. These cooling systems typically contain several metals such as iron,
steel, brass, copper, or aluminum. The range of properties of the materials of
construction greatly complicates formulation of an effective corrosion-control
additive package. Chromate-based additive packages have proven to be very
31
-------
CHROMIUM AND NICKEL
stable and reliable for corrosion control in multimetal cooling water systems.
Because of environmental concerns about chromate releases, many vendors are
developing effective non-chromate cooling water treatment additive packages.
Expand use of non-chromium treatment
chemicals. A variety of non-chromium addi-
tive packages are available and in use for
specific applications.
Refractories
Research needs. Research is needed to op-
timize and demonstrate available corrosion
control additive packages in mixed metal
cooling systems under a wide range of pH and
oxidation/reduction potential conditions and
high heat flux.
Chromium is used in ceramic refractories for furnace lining materials that can resist
high temperatures. Chromic oxide has very low solubility in molten glass, so
chromic oxide bricks are used to line glass-making furnaces.
Use non-chromium refractories. It may be
possible to develop refractory materials that do
not rely on chromium additives to increase
temperature resistance.
Research needs. Research is needed to de-
termine the performance requirements for
refractories in specific applications and to iden-
tify test methods to measure the performance
with respect to those standards. Then candi-
date refractories can be identified and tested
as alternatives for chromium-containing refrac-
tories in specific applications.
Catalysts
Nickel and chromium are used as catalysts in many industrial applications. Nickel
catalysts find extensive application in the food processing industry for hydrogena-
tion of edible and inedible oils. Nickel and chromium are essential in several steps
in ammonia manufacture. Nickel catalysts are used in the primary and secondary
reforming and methanation in ammonia production. Chromium catalysts are used
in the high-temperature shift reaction in ammonia production. Combined nickel-
chromium catalysts allow selective hydrogenation of olefins for use in ethylene
manufacture. Nickel catalysts are also used for methanation of fuel gas in the
petrochemical industry. Chromic oxide catalyzes hydrogenation-dehydrogenation
reactions. Unlike metal oxides, chromic oxide will catalyze hydrogenation of both
the C=O and C=C double bonds. Chromic oxide or various chromate salts can be
used to catalyze the production of alcohols; dehydrogenation of alcohols; or
hydrogenation of esters, aldehydes, and ketones.
Change synthesis path to avoid the need
for a catalyst. Different combinations of
chemical feedstocks may allow preparation of
Research needs. Research is needed to de-
termine the requirements for specific reactions
and to identify test methods to measure the
32
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CHROMIUM AND NJCKEL
the desired product without the need for a
catalyst.
Optimize the system to reduce catalyst use.
Improved reactor design or control can im-
prove yields and reduce the need for catalysts.
The classic continuous-stirred tank reactor may
not be the best choice. Staged plug flow
reactors can give better control of reaction
conditions (Licis et al., 1991; Nelson, 1990).
Guard beds could be used to remove poisons
before the reacting mixture is sent to the
catalyst process.
Improve reaction yield with the catalyst.
Design of the catalyst and its support will
significantly affect the yield and product mix of
the reaction and the resistance of the catalyst
to poisoning. Changes in the formulation of
the catalyst; how it is made; or its size, shape,
porosity, and other physical properties can
improve the performance of the reaction or
increase catalyst life (Licis et al., 1991) and
(Nelson, 1990).
Use a nonhazardous catalyst. It may be
possible to identify alternative catalysts that
give the same performance as chromium or
nickel without increasing cost.
Recycle catalysts. Thermal and other regen-
eration techniques are available to remove
poisons or otherwise process spent catalysts
for reuse.
purity, yield, and other requirements. Then
candidate reaction paths can be identified and
tested as alternatives for paths requiring
chromium or nickel-containing catalysts.
Research needs. Research is needed to opti-
mize catalyst performance with specific reac-
tions includes determining reaction kinetics,
developing optimum reactor designs, and
developing improved measurement and control
systems. Research is needed to identify
materials for guard beds to protect catalysts
from poisons that degrade catalyst perfor-
mance. The guard bed material would need to
be compatible with the process materials,
remove the poisons, and have low environ-
mental impact.
Research needs. Research is needed to
reduce the use of chromium or nickel catalysts
by improving catalyst performance includes
identifying and validating improved catalyst
support matrices and developing catalysts with
improved selectivity.
Research needs. Research is needed to de-
termine the requirements for specific reactions
and to identify test methods to measure the
purity, yield, and other requirements. Then
candidate nonhazardous catalysts can be
identified and tested as alternatives for chromi-
um- or nickel-containing catalysts.
Research needs. Research is needed to de-
termine the requirements for specific catalyst
recycle applications and to identify test meth-
ods to measure the purity, yield, and other
requirements. Then candidate catalyst recycle
treatments can be identified and tested as
alternatives to extend the life of chromium- or
nickel-containing catalysts.
33
-------
CHROMIUM AND NICKEL
Wood Treatment and Preservation
The wood preserving industry has been through several material changes to
continue to provide durable wood products while reducing the hazards of treatment
chemicals. The industry shifted from creosote to pentachlorophenol and most
recently to chromated copper arsenate (CCA) for wood treatment.
Replace CCA as chemical treatment for
wood preserving. Although an improvement
over earlier wood preservatives, CCA still
presents environmental concerns. Develop-
ment of alternative treatments is desirable.
One candidate is copper naphthenate (Licis et
al., 1991).
Pigments and Oxides
Research needs. Research is needed to de-
termine the performance requirements for
wood preservatives and to identify test met-
hods to measure the performance with respect
to those standards. Then candidate' preser-
vatives can be identified and tested as alterna-
tives for CCA.
Chromates are used to produce a wide range of yellow, orange, and green
pigments. Zinc and strontium chromate pigments are used as corrosion-inhibiting
priming coat under other paints. An expanding market for chromium oxide is as
a component in the magnetic media in high-performance recording materials.
Black and green nickel oxides are used in the ceramic industry. Nickel oxide is
added to ceramic formulations for porcelain enameling of steel to improve
adhesion. Nickel oxides are also used in specialty ceramics such as nickel-zinc
ferrites for magnets and nickel silicides for high-temperature electrical conductors.
Various nickel compounds are used to color ceramic glazes. Organic nickel
compounds are used as dyes.
Do not use a pigment or oxide. Methods
may be available to avoid the need for chromi-
um or nickel pigments or oxides.
Use nonhazardous pigment or oxide.
Alternative nonhazardous materials may be
available.
Research needs. Research is needed to de-
termine the performance requirements for
chromium or nickel pigments or oxides and to
identify test methods to measure the perfor-
mance with respect to those standards. Then
candidate materials can be identified and
tested as alternatives for chromium and nickel
pigments and oxides.
Research needs. Research is needed to de-
termine the performance requirements for
chromium or nickel pigments or oxides and to
identify test methods to measure the perfor-
mance with respect to those standards. Then
candidate materials can be identified and
34
-------
Minimize use of chromium or nickel pig-
ment or oxide. There may be ways to mini-
mize the use of chromium or nickel pigment.
Use non-chromium oxide recording media.
Metal powder-based magnetic recording mate-
rial is available; however, its use is limited by
cost and problems with oxidation on the media.
Avoid the use of chromium recording
media. Methods such as laser disk data
storage are available and could reduce the
reliance on magnetic media for data storage.
Battery Manufacture
CHROMIUM AND NJCKEL
tested as alternatives for chromium and nickel
pigments and oxides.
Research needs. Research is needed to de-
termine the performance requirements for
chromium or nickel pigments or oxides and to
identify test methods to measure the perfor-
mance with respect to those standards. Then
candidate materials can be identified and
tested as alternatives for chromium and nickel
pigments and oxides.
Research needs. Research is needed to
develop and validate methods to reduce cost
and increase the corrosion resistance of metal
powder magnetic recording media.
Research needs. Research is needed to
develop methods to reduce the cost and
increase the flexibility of optical data recording
systems.
Porous electrodes made from nickel powder are used in rechargeable and high-
performance batteries and fuel cells. Nickel-cadmium rechargeable batteries are
used in many applications because they allow many discharge/charge cycles, have
a long shelf life, and can be recharged quickly.
Replace nickel-based batteries and fuel
cells. Alternative materials may be available
for battery and fuel cell applications.
Research needs. Research is needed to de-
termine the performance requirements for
rechargeable and high-performance batteries
and to identify test methods to measure perfor-
mance with respect to those standards. Then
candidate materials can be identified and
tested as alternatives for nickel.
Leather Tanning
Tanning processes treat hides and skins to improve flexibility, durability, and
resistance to microbial attack, producing leather that is useful for commercial
applications. Chromium tanning gives a stable hide fiber which resists microbial
attack and high temperatures. Chromium tanning is usually done in a single bath.
In the single bath process, hides that have been soaked in an acidic solution of pH
3 are immersed into a solution of trivalent chromium salt, typically chromium
35
-------
CHROMIUM AND NICKEL
sulfate. After the chromium salt penetrates into the hide, the pH is raised to cause
the chromium to react with proteins in the hide.
Use a less hazardous tanning agent. Vege-
table, aldehyde, and oil tanning can be used
for limited applications but chromium tanning is
still the most common process. The main
advantages or chromium tanning are high
processing speed, low cost, minimum discolor-
ing, and good preservation qualities. It may be
possible to improve vegetable or oil tanning to
provide increased strength, acceptable color,
and improved resistance to microbial attack.
Research needs. Research is needed to
develop non-chromium tanning processes that
give acceptable quality leather and good
preservative properties.
REFERENCES FOR CHROMIUM AND NICKEL
Bibber, John W. 1991. "Sanchem-CC: A Chrome-Free Aluminum Pretreatment
System." In: Sixth Annual Aerospace Hazardous Waste Minimization Conference.
Boeing, Seattle, Washington, June 25-27.
Bureau of Mines (BOM Cr). 1988. Chromium Minerals Yearbook. U.S.
Department of the Interior.
Bureau of Mines (BOM Ni). 1988. Nickel Minerals Yearbook. U.S. Department
of the Interior.
Carrillo, G., J. Mnich, and R. Werley. 1991. "Sulfuric/Boric Acid Anodize as an
Alternative to Chromic Acid Anodize." In: Sixth Annual Aerospace Hazardous
Waste Minimization Conference. Boeing, Seattle, Washington, June 25-27.
Dickens, Paul S., and Paul M. Cannon. 1991. "Reducing Chromium Waste in
Silicon Wafer Production." Hazmat World. 4(9): 50-52.
Evanoff, S.P. 1990. "Hazardous Waste Reduction in the Aerospace Industry."
Chemical Engineering Progress. April, pp. 51-52.
Gresham, Robert M. 1991. "Physical Vapor Deposition Surface Treatments as
an Environmentally Friendly Alternative to Hard Chrome Plating." In: Sixth Annual
Aerospace Hazardous Waste Minimization Conference. Boeing, Seattle,
Washington, June 25-27.
Groshart, Earl. 1989. "Molybdenum — A Corrosion Inhibitor." Metal Finishing,
87(1), January.
36
-------
CHROMIUM AND N1CKEL
Guffie, Robert K. 1986. "Hard Chrome Plating." Products Finishing, 51(2),
November.
Licis, Ivars J., Herbert S. Skovronek, and Marvin Drabkin. 1991. Industrial
Pollution Prevention Opportunities of the 1990s. EPA/600/8-91/052, Task 0-9,
Contract 68-C8-0062. Risk Reduction Engineering Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio, August.
Nelson, K.E., 1990. "Use These Ideas to Cut Waste." Hydrocarbon Processing,
March.
PsF, Products Finishing. 1988. "Turn to Trivalent." Products Finishing, October.
Schiffelbein, Daniel V. 1991. "Evaluation of Ni-W-SiC Plating as Replacement for
Chromium Plating." In: Sixth Annual Aerospace Hazardous Waste Minimization
Conference. Boeing, Seattle, Washington, June 25-27.
Stewart, Thomas G. 1991. "Non-Chromated Desmutter Prior to Penetrant
Inspection of Aluminum." In: Sixth Annual Aerospace Hazardous Waste
Minimization Conference. Boeing, Seattle, Washington, June 25-27.
Walker, Jr., J.F., J.H. Wilson, and C.H. Brown, Jr. 1990. "Minimization of
Chromium-Contaminated Wastewater at a Plating Facility in the Eastern United
States." Environmental Progress, 9(3); August.
37
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CYANIDE POLLUTION PREVENTION RESEARCH NEEDS
FOR THE 33/50 PROGRAM
SOURCES AND PRODUCTION
CHARACTERISTICS AND RATES
The name "cyanide" refers broadly to any molecule or ion that contains the
carbon-nitrogen triple-bonded group -CsN. This includes, for example:
Hydrogen cyanide (hydrocyanic acid, prussic acid, formoni-
trile), HCN, which is a colorless, poisonous, low-viscosity
liquid (melting point, or mp, -13.24°C; boiling point, or bp,
25.70°C). Hydrogen cyanide is a weak acid (pKd=8.89 at
18°C) and is not normally corrosive, with two exceptions:
aqueous solutions can cause trans-crystalline stress-
cracking of carbon steels, and aqueous solutions containing
HCN and sulfuric acid as a stabilizer severely corrode steel
above 40°C and stainless steels above 80°C (Kirk and Oth-
mer, 1979).
Alkali metal and alkaline earth cyanides are usually white,
ionic, crystalline powders. Sodium cyanide, NaCN, is often
called white cyanide. It is stable in water as an anhydrous
salt above 34.7°C and as a dihydrate below 34.7°C. The
solubility of NaCN-2H2O is 45 g (NaCN)/100 g solution, and
decreases markedly with decreasing temperature. In
aqueous solutions of NaCN, the cyanide ion is considered
free, i.e., it does not completely form ion pairs with sodium
ions. Free cyanide is quite toxic.
Cyanide also forms strong complexes with iron, such as
ferrocyanide and ferricyanide. Strongly complexed cyanides
are resistant to breakdown and are low in toxicity.
Hydrogen cyanide enters the human body by inhalation, skin absorption, or orally.
It is described as having the odor of bitter almonds, but one of five people cannot
sense this odor, causing it to be all the more dangerous to them. Major uses of
HCN are acrylonitrile, other nitriles, acrylates for plastics, and intermediates, such
as for production of NaCN. Other products are ferrocyanides, chelating agents,
optical laundry bleaches, and Pharmaceuticals. Hydrogen cyanide is encountered
as an industrial waste through the production of HCN and when other cyanide
compounds are acidified.
Sodium and potassium cyanides are the only important alkali metal cyanides. As
toxins, they behave similarly to HCN when taken orally or through the skin. They
38
-------
CYANIDE
can evolve HCN if exposed to moisture, such as in humid air. Sodium cyanide is
used for gold and silver metallurgical extraction, Pharmaceuticals, vitamins,
plastics, ferrocyanides, and for electroplating of copper, zinc, cadmium, gold, and
silver. Potassium cyanide is used in electroplating, and together with NaCN in
nitriding steel, refining platinum, and in metal coloring processes. Calcium cyanide
is the only alkaline earth metal cyanide used commercially. It is largely used in
ore refining, for extraction and flotation, in the production of ferrocyanides for case
hardening of steel, and also as a fumigant, rodenticide, and insecticide. See Table
6 for cyanide's pollution prevention needs.
Metal cyanides used commercially include nickel cyanide, which is used as a
brightener in plating of other metals, and silver cyanide and zinc cyanide, which
are used, respectively, in silver and zinc plating. In the plating process, these
metals form complex cyanides, such as ferrocyanide and ferricyanide complexes
with iron. Although these complexes are less toxic, they are also resistant to
removal by treatment processes, and are decomposed by ultraviolet light, so that
there is a possibility of generating HCN in waste streams containing cyanide
complexes discharged by industry. Another waste source of cyanide is from spent
pot liners used in aluminum refining.
Certain organic cyanides, called nitriles, are used as intermediates in chemical
products and as a copolymer in plastics such as acrylonitrile/butadiene/styrene.
The organic cyanide intermediates are not nearly as toxic as the inorganic
cyanides.
POLLUTION PREVENTION OPPORTUNITIES
AND SUPPORTING RESEARCH NEEDS
Electroplating
Cyanide waste generated in metal finishing comes primarily from copper, zinc,
cadmium, silver, and gold plating, where large amounts of sodium and potassium
cyanides and smaller amounts of metal cyanides are used. A considerable volume
of wastewater is produced in the finishing industry. This waste usually contains
dilute cyanide (10 to 770 ppm) from rinsing.
Due to process changes that do not use cyanide baths and the increasing use of
cyanide recovery systems, cyanide waste is expected to decline greatly in the
future.
39
-------
RCH NEEDS
, Research Needs
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Use alternatives to cyanide in plating pro-
cesses. Sodium cyanide is considered to be
a multipurpose ingredient in many plating
operations, but is especially important when
plating the more noble metals. However,
many alternatives are now being investigated
for pollution control.
CYANIDE
Research needs. Research is needed to
develop non-cyanide processes that can
provide acceptable performance features.
Some examples of systems being studied are
acid fluoroborate in cadmium plating, copper
pyrophosphate or copper sulfate in copper
plating, gold sulfite in gold and gold alloy
plating, silver succinimide and silver sulfite/
thiosulfate in silver plating, and acid chloride
and alkaline noncyanide zinc baths for zinc
plating.
Mining and Ore Processing
Sodium and calcium cyanides are used as a flotation depression agent in
processing of copper, lead, and zinc ores. Cyanide complexing agents are used
to extract silver and gold from ores. Cyanide is discharged with effluent water
from mill tailings, which are usually untreated.
Find flotation modifiers and extractants to
replace cyanide chemicals in ore process-
Ing. It may be possible to extract copper,
lead, and zinc from their ores by a process
that does not involve the use of cyanide.
Primary Metals
Research needs. Research is needed to find
alternative methods to provide flotation depres-
sion or extraction characteristics of cyanide
salts in ore separation.
Considerable amounts of cyanide are generated in steel production from coking
operations and from carryover into blast furnace dust and sludges. Additionally,
cyanide waste is generated in cold finishing of steel. In the aluminum industry,
cyanides are generated in the process conversion of cryolite to aluminum metal.
Research needs. Research is needed to
control the escape of HCN gases in coking
operations.
Control release of cyanide in coking opera-
tions. Although recovery of HCN from coke-
oven gases received little attention in past
decades, environmental controls have spurred
new research and development in this area
(Ger. Pat., 1974).
Treatment Processes
A large number of treatment processes have been developed for cyanide
treatment and destruction. Some of the known processes are as follows (Conner,
1990):
41
-------
CYANIDE
Electrolytic oxidation (U.S. Pat., 1972)
Chemical oxidation (FMC Corp., 1975; Asturquimica, 1975;
Zievers et al., 1968)
Chemical reaction •....',
Acidification followed by HCN destruction ("Cyan-Cat") (Jola,
1976)
Evaporative recovery
Incineration or catalytic oxidation
Gamma irradiation
Reverse osmosis or electrodialysis (recovery)
Carbon absorption .
Carbon bed catalytic destruction
Foam separation
Waste-plus-waste (Qttinger et al., 1973) . , >;,
Freeze-out (recovery) .,,„'..,.
"Kastone" process (ES&T, 1971).
Nascent oxygen
Solvent extraction (recovery)
Aeration
Polymerization (U.S. Pat. 3,505,217)
Starch process (U.S. Pat. 3,697,421)
Improve electrolytic treatment process. A
considerable amount of research was done on
anodic oxidation processes in the 1950s and
1960s. However, the effluent from this kind of
treatment usually contains up to 10 ppm free
cyanide and therefore must be given a follow-
up treatment, such as by alkaline chlorination.
This problem has made electrolytic oxidation
uneconomical for dilute solutions.
A modification of this process has been pro-
posed by Shockcor (1972, see U.S. Patent
3,692,661), in which the space between the
anode and cathode is filled with carbon cylin-
ders or spheres which act like a semiconductor
bed to improve the conductivity of dilute solu-
tions.
Improve chemical oxidation treatment pro-
cess. The main problem is that although the
reaction of cyanide to cyanate (which is about
1000 times less toxic) is fast, further oxidation
of cyanate to carbon dioxide and nitrogen is
Research needs. Research is needed to
improve the electrolytic process to convert
more cyanide to cyanate and to decrease the
costs associated with chlorination.
Research needs. Research is needed to
improve the oxidation kinetics of cyanide to
cyanate, such as by using a catalyst or other
means.
42
-------
CYANIDE
quite slow. Also, chemical oxidation of com-
plex metal cyanides is very slow because of
their stability, so that the reactions may take
hours to weeks to approach completion. In the
Kastone process, organic glycolic compounds
are formed that may require biological treat-
ment before discharge. Furthermore, the
presence of any oxidizable organic species will
consume the oxidant and will be more costly.
Improve nonoxidation chemical treatment
process. A variety of cyanide reactions can
convert cyanide to less toxic substances or
even commercially valuable compounds. One
is the waste-plus-water method, in which
ferrous sulfate waste at high pH is used to
convert cyanide to ferrocyanide.
Organic polymerization, such as the reaction of
cyanide with aldehydes at elevated tempera-
tures to form nitriles and then hydrolyzed to
amino acids, which are biodegradable. Starch
conversion syrup has been used to produce a
nontoxic reaction product.
Improve acidification treatment process.
This process works by acidifying concentrated
cyanide wastes with a strong acid, such as
sulfuric acid, to decompose free and complex
cyanides into other metal salts and HCN. The
HCN is then stripped from solution in a desorp-
tion tower and catalytically oxidized in a ther-
mal reactor to produce carbon dioxide, nitro-
gen, and water vapor (the "Cyan-Cat" pro-
cess). The disadvantages are high capital
cost, inherent dangers of producing HCN gas,
and that dilute cyanide is left in solution, which
must be removed by some other method.
Advantages are that little auxiliary fuel is
needed because the exothermic combustion of
HCN provides almost all of the heat necessary
for combustion (350 to 400°C).
Research needs. Research is needed to
convert ferrocyanide products of the waste-
plus-water process to stable, nontoxic sub-
stances.
Research is needed to improve the efficiency
and economics of the organic polymerization
methods.
Research needs. Research is needed to
improve the efficiency of the "Cyan-Cat" pro-
cess so that a greater fraction of cyanide is
converted, and to investigate the safety of
operations in which HCN is handled.
43
-------
CYANIDE
Chemical Intermediates and Polymers
Important current uses of HCN include use in production of acrylonitrile, nylon
(adiponitriie intermediate product), and methacrylate polymers (acetone-cyanohy-
drin intermediate in formation of methyl methacrylate monomer). In 1991, U.S.
sales to major markets included:
acrylonitrile
acrylic polymers
(only portions use cyanohydrin process)
nylon
Total nylon + acrylonitrile
117 million Ib
672 million Ib
556 million Ib
673 million Ib
For comparison, U.S. polyethylene sales to major markets totaled -20,000 million
Ib (Modern Plastics, 1992). Recent research has targeted development of
processes that avoid the use of HCN and improve process efficiency.
Use alternatives to HCN-produced chemi-
cals. Chemical intermediates and polymers
that are prepared using HCN in their produc-
tion include some monomers and performance
polymers.
Control HCN-produced chemicals. Improved
control of these processes would reduce risk
and treatment needs.
Research needs. Research is needed to
identify and evaluate processes to minimize
the use of HCN in polymer production.
Research needs. Research is needed to
improve efficiency of processes to prepare
intermediates and polymers to reduce CN
waste.
REFERENCES FOR CYANIDE
Asturquimica, S.A. 1975. "Potassium Permanganate to Treat Cyanide Effluents."
Spain.
Conner, J.R. 1990. Chemical Fixation and Solidification of Hazardous Wastes.
Van Nostrand and Reinhold, New York.
ES&T. 1971. "New Process Detoxifies Cyanide Waste." ES&T5: 496-497.
FMC Corp. 1975. A Guidebook to Hydrogen Peroxide for Industrial Wastes,
Philadelphia, PA.
Ger. Pat 2,260,248 (June 12, 1974), H. Karwat (to Linde A.G.).
44
-------
CYANIDE
Jola, M. 1976. "Destruction of Cyanides by the Cyan-Gat Process." Painting
Surf. Finish., pp. 42-44, September 1976.
Kirk, R., and D. Othmer (Eds.). 1979. Encyclopedia of Chemical Technology, 3rd
ed., Vol. 7, John Wiley & Sons, New York, NY.
Modern Plastics. 1992. "U.S. Resin Sales." Modern Plastics, January, pp. 85-95.
Ottinger, R.S., J.L. Blumenthal, D.F. Dal Porto, G.I. Gruber, M.J. Santy, and C.C.
Shih. 1973. Recommended Methods of Reduction, Neutralization, Recovery or
Disposal of Hazardous Waste. EPA-670/2-73-053-f, Washington, DC.
U.S. Environmental Protection Agency. 1988. 1988 Toxics Release Inventory
(TRI) Releases/Transfers Database, Washington, DC.,»-
U.S. Pat. 3,505,217.
U.S. Pat. 3,692,661 (Sept. 19, 1972) to M.H.'Shockcor.
U.S. Pat. 3,697,421.
Zievers, J.F., R.W. Grain, and F.G. Barclay. 1968. "Waste Treatment in Metal
Finishing: U.S. and European Practice." Plating, 55: 1171-1179.
45
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5 LEAD POLLUTION PREVENTION RESEARCH NEEDS
FOR THE 33/50 PROGRAM
SOURCES AND PRODUCTION
CHARACTERISTICS AND RATES
Lead (chemical symbol Pb) is a bluish-white, silvery, gray metal that is highly
lustrous when freshly cut, but tarnishes when exposed to air. It is very soft and
malleable; has a high density (11.35 g cm"3) and low melting point (327.4°C); and
can be cast, rolled, and extruded. Lead was well known in ancient times, and was
extensively used because of its ease of fabrication. ;
Lead occurs in the earth's continental crust at concentrations of about 15 g/ton, or
13 ppm (Hurlbut and Klein, 1977). Although lead is a comparatively rare element
in the earth's crust, lead ore deposits are unexpectedly numerous and widely
distributed throughout the world. In addition to galena (PbS), which is the major
ore mineral for lead, other source minerals include anglesite (PbSO4), cerrusite
(PbCO3), mimetite (PbCI2-3Pb3(AsO4)2), and pyromorphite (PbCI2-»3Pb3(PO4)2).
Lead is produced with other metals, such as zinc and copper, then smelted to
remove impurities.
Of the estimated 1,400,000 tons of lead consumed in 1990, the U.S. Bureau of
Mines (1991) has estimated apparent consumption patterns for lead as follows:
batteries
ammunition
non-battery oxides
cast, sheet, or extruded products
solder
other uses
80%
5%
4%
4%
1%
6%
About half of the lead used in the United State comes from recovery and
reprocessing of scrap lead. The main sources of scrap are battery plates,
drosses, skimmings, solders, babbitts, and cable sheathing. Of these secondary
sources of lead, storage batteries make up more than half the total recovered.
Channels for collecting used batteries are well emplaced, so that >90% are recov-
ered for recycling.
Lead has two oxidation states, +II and +IV, with the former being more common.
Pb(ll) compounds are regarded as ionic, whereas Pb(IV) compounds are covalent.
Table 7 shows the pollution prevention research needs for lead.
46
-------
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50
-------
LEAD
Lead is an amphoteric metal, meaning that its oxides and hydroxides form both
acidic and basic aqueous species. Almost all lead compounds are produced from
pig lead to form lead monoxide, PbO, which is also called litharge. Other oxides
of lead are PbO2, the mixed oxide Pb3O4, and a black oxide (lead suboxide) that
contains 60 to 80% PbO and the rest finely divided lead metal.
Lead and its compounds are cumulative poisons. However, because of its long
history of use, more is known about lead poisoning than about poisoning by any
other metal. Allowable lead levels have been established for drinking water, and
various regulatory controls are in place for disposal of lead-bearing wastes. Lead
is a probable human carcinogen, and it may also damage human chromosomes.
It causes a range of systemic effects, including central nervous system and behav-
ioral effects. It causes adverse acute and chronic effects in aquatic organisms and
can be bioconcentrated.
POLLUTION PREVENTION OPPORTUNITIES
AND SUPPORTING RESEARCH NEEDS
Emissions from Primary Lead Smelting
Smelting of lead ores is a source of lead emissions to the air, soil, and water. The
primary method of lead smelting is the sinter-blast furnace method (Kirk and
Othmer, 1979). Process modifications, such as using updraft sintering in place of
downdraft sintering, have led to improvements in plant hygiene, as well as
increases in output, economic production, and blast furnace performance. Still,
overall problems in air pollution and waste disposal have led to the development
of new approaches in lead smelting (AIME, 1979). Thermalinefficiency is inherent
in the two-stage sinter-blast-furnace process. The heat generated by exothermic
reactions should be adequate to reduce lead concentrates to metallic lead, but in
practice additional fuel is needed. A one-stage process would be more efficient
and would generate less waste. A number of one-stage processes have been
commercialized or developed at the pilot scale (Matyas and Mackey, 1976).
These include smelting lead concentrates and fluxes with oxygen-enriched air.
Their products include sulfur-bearing bullion, slag, and a sulfur dioxide-rich gas.
Develop an electrolysis process to help
eliminate air pollution. The U.S. Bureau of
Mines has been investigating a hot iron chlo-
ride-sodium chloride leach-electrolysis tech-
nique to produce lead from galena. The filtrate
contains > 99% of the lead, which is precipitat-
ed as lead chloride and electrolyzed to yield
lead metal and chlorine gas.
Research needs. New developments of
improving lead production technology should
be investigated. These may include improve-
ments and adaptations of traditional pyrometal-
lurgical and electrorefining processes. Conver-
sion from batch to continuous modes of opera-
tion is a prime objective of future processes.
51
-------
LEAD
Alloys
Lead is easily fabricated because of its softness, but it is not easily drawn because
of its low tensile strength and absence of work-hardening at room temperature
(Kirk and Othmer, 1979). Alloying is commonly done to add strength and other
useful properties. The most commonly used elements for this purpose are copper
(Cu), antimony (Sb), calcium (Ca), tin (Sn), arsenic (As), tellurium (Te), silver (Ag),
and strontium (Sr). Bismuth (Bi), cadmium (Cd), and indium (In) are used less
often for this purpose.
Lead-Copper Alloys. Alloying with copper produces considerable grain
refinement and gives resistance to grain growth. Adding 0.04 to 0.08% copper (by
weight) in lead, with or without the addition of silver, produces ASTM B 29-79
grades, which are suitable for sulfuric acid containment. Larger amounts of
copper, 64% Cu (eutectic) or higher, are added in leaded brass or bronzes.
General uses include stock for bearings and bushings in the automotive and
aircraft industries, lead sheet, pipe, and wire. Lead-copper alloys are also used
for continuous extrusion of lead cable coverings in electrical power cable.
Extruded or rolled alloys contain uniformly dispersed copper particles that produce
a self-passivating layer of lead sulfate on the alloy surface in sulfuric acid
solutions.
Lead-Antimony Alloys. Lead-antimony comprises the most important class of
lead alloys. Almost all lead products use antimony alloys in some fashion. Most
commercial alloys contain 11.1% Sb (eutectic) or less. The solubility of antimony
in lead decreases from 3.5% Sb at 252°C to 0.25% Sb at room temperature. This
behavior allows Pb-Sb alloys to be precipitation-hardened by proper heat treatment
procedures. The rate at which the alloy is cooled and its composition can be
controlled to give a wide variety of mechanical properties. Like Pb-Cu alloys, Pb-
Sb alloys develop a protective coating of lead oxide and lead carbonate that keeps
them practically inert to further oxidative attack. Lead-antimony alloys are used
for flashing material in roofing, and for making ammunition. Lead shot contains 0.5
to 8% Sb and has an arsenic content equal to about 20 to 30% of the Sb content.
Arsenic is used to reduce any lead or antimony oxides present in the molten
material and helps improve roundness of the globules during production;
quenching is done by dropping the shot into towers of water. Shot larger than 5.8
mm and bullets are cast.
The principal use of Pb-Sb alloys is in the manufacture of grids, straps, and
terminals for lead storage batteries. The antimony content of the lead alloy
improves creep resistance and castability, which increase up to the eutectic point.
It also provides a rigid strengthening network, which is important for hardness and
stiffness of cast grids. Conventional automotive batteries use 4 to 6% Sb alloys
for grids. New low-gassing, maintenance-free batteries use only 1.8 to 2.75% Sb.
Large industrial batteries, deep-discharge batteries, and electric-vehicle batteries
52
-------
LEAD
use higher (5 to 9%) Sb contents.
commonly made from a 3% Sb alloy.
Internal connections and terminals are
Lead-antimony (0.5 to 1.0%) alloys are also used for cable sheathing, and provide
higher strength, and resistance to vibration than Pb-Cu alloys. The excellent
strength of Pb-Sb alloy cables permit them to be reeled and unreeled and bent
around corners without cracking or breaking.
Alloys with less than 3.5% Sb have structures that are highly susceptible to
solidification-shrinkage porosity and cracking. This problem is overcome by the
addition of nucleating agents, such as copper and arsenic, sulfur, or selenium.
Other uses Pb-Sb alloys include anode material for metal electrowinning and metal
plating, qollapsible tubes, and wheel balancing weights for automobiles and trucks,
and specialty weights.
Lead Calcium Alloys. Low-calcium-lead alloys exhibit certain properties that give
them advantages over traditional Pb-Sb alloys. Extruded Pb-Ca alloys are much
stronger than either Pb-Cu or Pb-Sb (1%) alloys and have good ductility and
excellent fatigue and creep resistance. Pb-Ca is used mainly as a grid alloy for
large storage batteries because of its resistance to self-discharge and electrolyte
loss upon standing and under full charge conditions. These alloys are increasingly
being used for lead anodes in electrowinning, because they form a hard, adherent,
corrosion-resistant layer of PbO2 during use in sulfuric acid baths and greatly
reduce lead contamination in the product. Alloys of 0.04 to 0.07% Ca are
commonly used for these purposes, as well as for cable sheathing, sleeving, and
specialty tapes. Further strength and performance improvements have been
realized in the ternary system that includes tin, Pb-Sn-Ca, where 0.01 to 0.11 % Ca
and 0.3% Sn are used. Substitution of strontium for calcium in either the binary
or ternary system improves strength.
Lead-Tin Alloys. Tin alloys have lead in all proportions, providing a wide range
of alloy compositions for many different applications. Lead-tin alloys are mainly
used as solders. Generally, lead-tin solders range in composition from 30 to 98%
Pb. Pb(98%)-Sn(2%) solder is used to solder side seams of tin cans. However,
substitution of 0.5% silver for Pb significantly improves creep strength, which is
essential for pressurized cans. The high lead content and the practice of
pretinning cans permit soldering to be performed at high speeds. General-purpose
soldering is done with an alloy in the 40 to 50% tin range. Electronic soldering,
as for printed circuit boards, uses Pb(37%)-Sn(63%) alloys. Solders in the
composition range of 70 to 85% Pb are used for manufacturing automobile
radiators and other kinds of heat exchangers.
Lead-tin alloys are also used as coatings on steel and copper for corrosion
protection. Terne-coated steel is coated with an alloy of 80 to 85% lead. This
53
-------
LEAD
composition gives good wetting and surface alloying with the steel. These coated
sheets are used for radio and television chassis, roofs, fuel tanks, air filters, oil
filters, gaskets, radiator components, metal furniture, gutters, and downspouts.
Alloys of Pb(96%)-Sn are applied to copper sheet for building flashing. Other
alloys of Pb, in the 50% Sn range, are used to coat steel and copper electronic
components for corrosion protection, appearance, and ease in soldering.
Lead and Pb-Sn coatings can also be applied by electroplating, usually from a
fluoroborate solution. This method allows the coating to be applied in any desired
thickness. Ordinarily, electroplated coatings are not used for corrosion protection,
because they tend to be porous.
Lead-Antimony-Tin Alloys. The Pb-Sb-Sn system is an important series of alloys
used in industry. Some materials made in this series include printing-type, lead-
base sleeve bearings, special casting alloys, slush castings, and decorative
casting alloys. These alloys are characterized by low melting points, high
replication of detail in printing and mold in casting, and high wear hardness and
strength, even at elevated temperatures. Kirk and Othmer (1979) provide proper-
ties of printing-type alloys and lead-base bearings. Pb-Sb-Sn alloys are also used
in bushing and sleeve bearings, for their antifriction properties. They are used to
make journal bearings in freight cars and mobile cranes. Arsenic and copper
additives are also used to improve compression-, fatigue-, and creep-resistant
properties at high temperature.
Lead-Silver Alloys. Lead-silver (0.75 to 1.25% Ag) alloys are used as insoluble
anodes in zinc and manganese electrowinning. These alloys form a conductive
layer of PbO2 on the surface in sulfuric acid, which prevents lead contamination
on the zinc or manganese coating.
Lead-Tellurium Alloys. Low tellurium (0.04 to 0.10%) alloys are used in
fabrication of chemically resistant pipe and sheet. They are also used in materials
for x-ray and nuclear radiation shielding.
Use a non-lead alloy. Non-lead alloys may
be used to fabricate products that do not
specifically require lead's physical properties to
perform their functions. For example, bear-
ings, bushings, pipe, wire, .cable coverings,
and flashing material may be constructed from
metals that do not contain lead. Another
example is to use alternative materials in place
of terne-coated steel for use in radio and
television chassis. In addition, use another
Research needs. Research is needed to
examine the properties of pure metals and
alloys in order to determine if they may be
adapted for use in place of lead alloys.
54
-------
LEAD
metal or alloy for casting and making printing-
type.
Use a plastic or composite alternative.
Products that do not require lead's electrical or
physical properties to perform their functions
may be fabricated instead from plastic or
composite materials. Substitutions of this sort
may be possible in low-temperature applica-
tions, such as decorative cast materials.
Another example would be to use plastic or
glass containers for food storage instead of
metal cans, which have lead-solder joints. Use
plastics or composites in place of terne-coated
steel for use in gutters, downspouts, and
furniture. Use a high-impact composite materi-
al for making printing type.
Use a ceramic material alternative. An
alternative substrate, such as an advanced
ceramic, may be use in place of lead alloys for
purposes of wear resistance or chemical
inertness. For example, machine components
such as bearings or bushings may be replaced
by ceramics. Ceramic coatings may also be
applied to base metals in order to be used for
containing caustic chemicals.
Use a non-lead solder. Low-melting electri-
cally conductive, corrosion-resistant alloys may
be found in a non-lead system. Non-lead
solders are now being used in household
plumbing. Non-lead solders may also be used
to form joints in canning. In electronics, some
success has been found using electrically
conducting epoxies in place of solder.
Eliminate ancillary hazardous materials
from lead-alloy processes. Eliminate the use
of arsenic by controlling oxidation of lead in
melts using some other chemical or electro-
chemical method. Eliminate the use of arsenic
Research needs. Research is needed to
examine the properties of plastics and com-
posites in order to determine if they may be
adapted for use in place of lead alloys.
Research needs. Research is needed to
examine the properties of advanced ceramic
materials in order to determine if they may be
adapted for use in place of lead alloys.
Research needs. Research is needed to
examine the properties of alternative metals to
be used in place of conventional lead solders.
Replacement solders must have melting points
near those of conventional solders and pos-
sess similar flow and adhesion characteristics.
Research is needed to find and improve ways
of making electrical connections without using
solder. Electrically conducting epoxies already
exist, but they have limitations.
Research needs. Research is needed to
understand what redox conditions exist at melt
temperatures, in order to develop alternative
methods for controlling the oxidation state of
lead in the melt.
55
-------
LEAD
and selenium by controlling solidification
shrinkage using sulfur or some other chemical
additive. Prevent arsenic and selenium from
entering the waste stream by careful attention
of their use.
Research is needed to find what structural
controls can be used in place of arsenic to
prevent shrinkage.
An investigation of arsenic and selenium loss
in lead production processes should be con-
ducted to determine if greater concern should
be attached to their usage.
Research needs. Areas of need may exist to
reduce waste and improve recycling in tradi-
tional processing operations.
Research needs. Research is needed to
improve the performance of separation tech-
nology. Ion-specific techniques may be used
in this regard.
Optimize traditional alloying operations. If
lead alloys cannot be avoided, improvements
can be developed to reduce waste in tradition-
al operations.
Recover or recycle lead in alloying process.
Develop methods to remove impurities in lead
alloys used for casting, plating, or other pro-
cesses, to extend lifetime of the melt. For
example, ion-specific separation methods may
be needed to allow reprocessing.
Storage Batteries
About half of the total U.S. lead consumption is for manufacture of automobile and
other storage batteries. A typical automobile battery contains the following
component distribution:
lead alloy (5% Sb) 36%
lead oxides and sulfate 34%
case (hard rubber or polypropylene)
and separators (PVC) 30%
Use an alternative cell design. The technol-
ogy involved in the lead storage battery is fairly
old and well entrenched in a number of impor-
tant applications, for example in automobile
electrical systems. Nevertheless, it may be
possible to develop a different electrochemical
cell that will meet the power storage require-
ments of modern internal combustion engines
or of future engines.
Use recycling. To recover the lead compo-
nents, several approaches have been used:
Research needs. This is a fairly mature
technology that probably cannot be changed
by a simple substitution of components.
Research is needed to find new alternatives in
electric power storage.
Research needs. A system for recycling can
be created so that virtually all lead-acid batter-
ies are recovered.
56
-------
LEAD
(1) the battery case may be broken manu-
ally, the sulfuric acid poured off, and
plates removed;
(2) the battery case is crushed and
screened, and the components are
separated by density;
(3) the complete battery is drained of acid
smelted in a blast furnace; the organic
components serve as fuel and as re-
ducing agents.
Canonie Environmental Services, Inc., has
recently developed a cleanup operation for the
Gould Battery Superfund site in Portland,
Oregon. A field demonstration involving 250
tons of material was processed using a 10-
ton/hour unit (HazTECH News, 1992).
Catalysts
Lead compounds are used as catalysts in polymer manufacture and other
reactions (Kirk and Othmer, 1979), for example:
Lead fluoride is used in the manufacture of picoline, a pyri-
dine compound (Ger. Offen. 1,903,879);
Lead chloride is used as a co-catalyst for producing
acrylonitrile (Fr. Pat. 1,556,127), and for polymerization of
alpha-olefins to highly stereoregular polymers (Brit. Pat.
1,078,854);
Lead carbonate catalyzes the polymerization of formalde-
hyde to high-molecular-weight crystalline poly-oxymethylene
products (Jpn. Pat. 18,963);
Basic lead carbonate, 2PbCO3.Pb(OH)2, or white lead, was
once the major white hiding pigment before replacement
with TiO2, but is still used for its catalytic properties for
preparing polyesters from terephthalic acid and diols (Jpn.
Pat. 64 20,533);
Lead sesquioxide, Pb2O3, is used as an oxidation catalyst
for carbon monoxide in exhaust gases (Ger. Offen.
2,142,001; Ger. Offen. 2,156,414);
Pb3O4 is used as a catalyst for combustion of carbon
monoxide in exhaust gases.
In recent years, many producers have been pursuing non-lead components.
57
-------
LEAD
Change synthesis path to avoid the need of
a catalyst or use a nonhazardous catalyst.
Different combinations of chemical feedstocks
may allow preparations of the desired product
without the need of a catalyst.
Electrical Components
Research needs. Research is needed to
determine the requirements for specific reac-
tions and to identify test methods to measure
the purity, yield, and other requirements. Then
candidate reaction paths can be identified and
tested as alternatives for paths requiring lead
compounds as catalysts.
Lead oxide, PbO, is most used in the manufacture of plates for lead-acid batteries.
Other uses of lead compounds in electrical components include:
Lead fluoride is used in making low power fuses (S. Afr.
Pat. 68 04,061); activators for electroless plating of nickel
on glass (Jpn. Kokai 74 27,442); electro-optical coatings
(U.S. Pat. 3,745,044); and in zinc oxide varistors (Jpn.
Kokai 74 14,996);
Lead telluride and lead arsenate are used in making semi-
conductors and photoconducting devices;
Lead zirconate titanate use for piezoelectric material;
Lead chloride is used as a photochemical-sensitizing agent
for metal patterns on printed circuit boards (U.S. Pat.
3,452,005);
Lead iodide is used in mercury-vapor arc lamps (Fr. Pat.
1,467,694; USSR Pat. 457,121);
Lead hydroxide is used in sealed nickel-cadmium battery
electrolytes (Jpn. Kokai 75 16,045);
Pb3O4 is used to make positive battery plates.
Use a different fluorescent gas in lamps. It
may be possible to use a substance other than
a lead halide to convert the mercury-vapor
spectrum to visible light in fluorescent lamps.
Use a non-lead material in electrical fuses.
Find an electrically resistive, low-melting point
substance to use in place of PbF2 in low
amperage fuses.
Recover or recycle activator solutions for
plating of nickel and other coatings. Solu-
tions containing a lead halide can be pro-
cessed for reuse to minimize waste. Tradi-
tional separation processes can be used to
Research needs. Research is needed to find
a replacement for fluorescent lead iodide in
mercury-vapor lamps, or to redesign the lamp
without using lead or mercury compounds.
Research needs. Research is needed to
study electrical resistance and other physical
properties of materials for use in fuses.
Research needs. To expand the uses of
current separation methods, such as evapora-
tion, reverse osmosis, or ion exchange for
processing spent plating solutions, research is
needed to improve performance with high-salt-
58
-------
LEAD
recycle solution that are no longer usable,
unless they are contaminated by impurities. If
the solution is contaminated with impurities,
more advance ion-specific separation methods
are needed to allow reprocessing.
concentrations and low-pH solutions (Walker et
al., 1990).
To extend the life of contaminated solutions,
new ion-specific separation methods meed to
be developed. Advanced selective ion separa-
tion methods to consider include advanced ion
exchange resins, crown ethers, or membranes.
Replace lead hydroxide in Ni-Cd batteries Research needs
Alternative materials may be available for
battery electrolytes.
Research is needed to determine the perfor-
mance requirements for rechargeable and
high-performance batteries and to identify test
methods to measure performance with respect
to those standards. Then candidate materials
can be identified and tested as alternatives
lead hydroxide.
Paints and Pigments
Lead compounds are not used as pigments in house paints any longer, since they
have been replaced by titanium dioxide, which is not toxic. However, lead
compound have historically been used in other areas of paint production as well.
Pb3O4 (red lead) is used as an anticorrosive pigment in
paint for steel surfaces;
Lead chromate is used in high tint strength pigments
(chrome yellow, chrome orange, and chrome green, a
mixture with iron blue) for road paints, plastics, leather, and
printing inks;
Lead phosphates are used for high temperature and
pearlescent pigments for plastics;
Lead sulfide is used as a pigment in inks;
A number of lead compounds, called metallic soaps, are
added to paints and varnish oils to hasten their drying.
Use nonhazardous materials for pigment.
Alternative nonhazardous materials may be
available for pigment to be used in paints,
varnishes, and inks.
Minimize use of lead pigments. It may be
possible to reduce the amount of lead oxide, or
other pigment, used on a coating material.
Research needs. Research is needed to
determine the performance requirements for
lead pigments and find alternative substances
that are nonhazardous.
Research needs. Research is needed to
determine the performance requirements for
lead pigments and to find methods of improv-
59
-------
LEAD
ing performance without adding more lead
pigment.
Research needs. Research is needed to find
alternatives to metallic soaps for acceleration
of paint and varnish drying.
Use non-lead-containing metallic soaps. A
large number of metals are used in soaps,
such as Al, Ba, Ca, Cu, Co, and Fe, in addition
to Pb. Specific lead chemicals include lead
tallage, lead naphthenate, and lead linoleate.
It may be possible to use other compounds to
accelerate drying of paints and varnishes.
Plastics and Rubber
Lead monoxide, PbO, is a component of heat stabilizers used for polyvinyl chloride
resins, for which 8,616 metric tons of lead salts were used in 1979 in the United
States (Smouluk, 1979). Specific lead compounds used in plastics include the
following:
Lead stearate is used as a vinyl stabilizer.
Dibasic lead phosphate is used as a stabilizer for PVC to
improve weathering resistance, thermal stability, and
electrical insulating properties; some applications include
garden hose, flexible and rigid vinyl foams, coated fabrics,
plastisols, electrical insulation, and extruded profiles for
outdoor use.
Lead naphthenate is used as an accelerator for vulcanizing
rubber.
Lead dioxide, PbO2, is used in the production of liquid
polysulfide polymers (Greninger et al., 1975).
Lead sesquioxide, Pb2O3, is used as a vulcanization accel-
erator for neoprene rubber (Jpn. Kokai 76 20,248).
Use components other than lead com-
pounds for stabilizers. Elimination of lead in
stabilizers would account for a large savings in
lead usage.
Use other substances that can act as vulca-
nization accelerators in natural and synthet-
ic rubbers. Alternatives to lead sesquioxide
and lead naphthenate, for example, may be
found to accelerate vulcanization.
Research needs. Research is needed to
determine if there are nonhazardous materials
that can be substituted for lead compounds to
give PVC and other polymers their weathering
resistance, thermal stability, and electrical
insulating properties.
Research needs. Research is needed to
explore alternative vulcanization accelerators
in natural and synthetic rubber.
60
-------
LEAD
Ceramics and Glasses
After batteries, the next largest use for lead is in the ceramics industry in glasses,
glazes, and vitreous enamels. The raw material, lead monoxide, or litharge, is
.used in ceramics and other industries. Lead monoxide combines with silicon
dioxide to form a low melting silicate (Jpn. Pat. 69 18,745) that is used in the
production of certain types of glazes and glass. When used as a glaze or vitreous
enamel, lead oxides are converted to mono-, bi-, and'tribisilicate frits to make the
lead compounds insoluble. Some other important lead compounds used in
ceramics and their properties are as follows:
Lead fluoride is added to glass coatings for infrared reflec-
tion (Ger. Offen. 1,421,872) and is used in phosphors for
television screens (Ger. Offen. 2,106,118).
,- • i PbCO3 is a white pigment used in ceramics.
Lead antimonate is used in tile painting, staining glass,
crockery, and porcelain.
Use nonhazardous materials for glazes and
vitreous enamels. Alternative nonhazardous
materials may be available as coatings.
Minimize use of lead compounds. It may be
possible to reduce the amount of lead used in
a glaze or vitreous coating.
Specialty Uses
Research needs. Research is needed to
determine the performance requirements for
lead compounds for glazes and vitreous coat-
ings and to find alternative substances that are
nonhazardous.
Research needs. Research is needed to
determine the performance requirements for
lead compounds in coatings and to find meth-
ods of improving performance without adding
more lead itself.
Lead compounds are used in a large number of industrial applications, for
example:
Lead oxide is used to make ammunition and detonating
agents.
Lead nitrite is used in explosives.
Lead iodide is used in lubricating greases (U.S. Pat
3,201,347). , , .
• Lead silicate is used in fireproofing fabric.
• Lead thiocyanate is used to make safety matches and car-
tridge priming.
Lead naphthenate is used as a wood preservative and
insecticide.
61
-------
LEAD
Sodium plumbite is used to remove sulfur compounds in
petroleum refining.
Lead arsenate and lead arsenite are used in insecticides for
larvae of gypsy moth, boll weevil, and other insect larvae.
Lead chloride (Brit. Pat. 1,235,100) and lead iodide (Brit.
Pat. 1,235,100) are used to make asbestos clutch and
brake linings.
An aqueous paste of lead bromide is used as general-pur-
pose welding flux for welding aluminum and aluminum
alloys to other metals (U.S. Pat. 3,287,540).
Lead chloride (U.S. Pat. 3,475,372) is used as a flame-
retardant inorganic filler in polycarbonates.
Lead bromide (Fr. Pat. 2,039,700) is used for flame retard-
ing in polypropylene, polystyrene, and ABS plastics.
Lead chloride is used as a flame retardant in nylon-6,6 wire
coatings (U.S. Pat. 3,468,843).
Lead dioxide, PbO2, is used because of its vigorous oxidiz-
ing power to smake matches and pyrotechnics, and to pro-
duce certain chemicals.
Lead bromide and lead iodide are used in film developing
as an intensifier.
Lead is used in wastewater filters to remove chromate.
Eliminate lead from lubricating grease. Use
alternative substances in lubricating grease
that will preserve the desired lubricating prop-
erties.
Use a substitute for lead compounds in
flame-retardant and heat-resistant materi-
als. Use alternative substances.
Use a lead-free compound for insecticides
and wood pres»ervatives. Find alternatives
for insecticides and wood preservatives that
are nonhazardous.
Research needs. Research is needed to
determine what physical properties are impart-
ed to lead-containing lubricating grease and to
find alternative substances.
Research needs. Research is needed to
understand how lead compounds behave to
give materials flame retardant and heat resis-
tant properties. Then, alternative compounds
that are nonhazardous may be sought to give
a material these same properties.
Research needs. Research is needed to find
suitable insecticides and wood preservatives
that do not contain lead.
62
-------
LEAD
REFERENCES FOR LEAD
AIME. 1979. "Lead-Zinc-Tin'80." In: AIME World Symposium on Metallurgy and
Environmental Controls, The Metallurgical Society of the American Institute of
Mining, Metallurgical, and Petroleum Engineers (AIME).
Brit. Pat. 1,078,854 (Aug. 9, 1967), (to Mitsui Petrochemical Industries, Ltd.).
Brit. Pat. 1,235,100 (June 9,1971), (to Toyota Central Research and Development
Laboratories, Inc.).
Fr. Pat. 1,467,694 (Jan. 27, 1976), (to N.F. Philips Goeilampenfabrieken).
Fr. Pat. 1,556,127 (Jan. 31, 1969), (to Imperial Chemical Industries, Inc.).
Fr. Pat. 2,039,700 (Jan. 15, 1971), J.A. Peterson and H.W. Marciniak (to Hooker
Chemical Corp.).
Ger. Offen. 1,421,872 (Feb. 19, 1970), W. Reichelt and H. Eligehausen (to W.C.
Heraeus GmbH).
Ger. Offen. 1,903,879 (Oct. 30,1969), S. Cane and LE. Cooper (to BP Chemicals,
Ltd., UK).
., Ger. Offen. 2,106,118 (Sept. 2, 1971), F. Auzel.
Ger. Offen. 2,142,001 (Apr. 6, 1972), T. Sakai, S. Kobayashi, K. Miyazaki, and M.
Yamamoto (to Mitsui Mining and Smelting Co., Ltd.).
Ger. Offen. 2,156,414 (July 13, 1972), Y. Kuniyasu, T. Sakai, and T. Ogami (to
Mitsui Mining and Smelting Co., Ltd.).
Greninger, D., V. Kollonitsch, and C.H. Kline. 1975. Lead Chemicals. Internation-
al Lead Zinc Research Organization, Inc., New York, p. 69.
HazTECH News. 1992. HazTECH News, 7: 13, Jan,. 23.
Hurlbut, C.S., Jr., and C. Klein. 1977. Manual of Mineralogy, John Wiley & Sons,
New York, pp. 123,124.
Jpn. Kokai 74 14,996 (Feb. 8, 1974), N. Ichinose and Y. Yokomizo (to Tokyo
Shibaura Electric Co., Ltd.).
Jpn. Kokai 74 27,442 (Mar. 11, 1974), K. Morimoto and M. Kuroda (to Matsushita
Electric Industrial Co., Ltd.)
63
-------
LEAD
Jpn. Kokai 75 16,045 (Feb. 20, 1975), Y. Morioka (to Sanyo Electric Co., Ltd.).
Jpn. Kokai 76 20,248 (Feb. 18, 1976), H. Kato (to Dainichi-Nippon Cables, Ltd.).
Jpn. Pat. 18,963 (Sept. 4, 1964), S. Futami (to Teijin Ltd.).
Jpn. Pat. 64 20,533 (Sept. 19, 1964), K. Nuruchina, Y. Takehisa, and J. Ichikawa
(to Toyo Rayon Co., Ltd.).
Jpn. Pat 69 18,745 (Aug. 15, 1969), M. Mikoda and T. Hikino (to Matsushita
Electric Industrial Co., Ltd.).
Kirk, R., and D. Othmer (Eds.). 1979. Encyclopedia of Chemical Technology, 3rd
ed., Vol. 14, John Wiley & Sons, New York.
Licis, Ivars J., Herbert S. Skovronek, and Marvin Drabkin. 1991. Industrial
Pollution Prevention Opportunities of the 1990s. EPA/600/8-91/052, Task 0-9,
Contract 68-C8-0062. Risk Reduction Engineering Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio, August.
Matyas*, A.G., and P.J. Mackey. 1976. J. Met, 28: 110, November.
Nelson, K.E., 1990. "Use These Ideas to Cut Waste." Hydrocarbon Processing.
March.
Sax, N., and R. Lewis. 1987. Hawley's Condensed Chemistry Dictionary, 11 th ed.
Van Nostrand.
S. Afr. Pat. 68 04,061 (Dec. 18, 1968), J. Prior and A. Florin (to Dynamit Nobel
A.G.).
Smouluk, G. 1979. Mod. Plast, 56: 74.
U.S. Bureau of Mines. 1991. Mineral Commodity Summaries.
U.S. Pat. 3,201,347 (Aug. 17, 1965), J.J. Chessick and J.B. Christian (to U.S.
Dept. of the Air Force).
U.S. Pat, 3,287,540 (Nov. 22, 1966), T.J. Connelly (to Allied Chemical Corp.).
U.S. Pat. 3,452,005 (Feb. 9, 1971), M.A. DeAngelo and D.J. Sharp (to Western
Electric Co.).
U.S. Pat 3,475,372 (Oct. 28, 1969), C.L. Gable (to Mobay Chemical Co.).
64
-------
LEAD
U.S. Pat. 3,468,843 (Sept. 23, 1969), W.F. Busse (to E.I. duPont de Nemours &
Co., Inc.).
U.S. Pat 3,745,044 (July 10, 1973), E.G. Letter (to Bausch and Lomb, Inc.).
USSR Pat. 457,121 (Jan. 15, 1975), S.G. Ashurkov, G.S. Sarychev, and E.F.
Fufaev; Chem. Abstr., 83:207,11 (1975). . . ,
Walker, Jr., J.F., J.H. Wilson, and C.H. Brown, Jr. 1990. "Minimization of
Chromium-Contaminated Wastewater at a Plating Facility in the Eastern United
States." Environmental Progress, 9(3): August. ,
65
-------
MERCURY POLLUTION PREVENTION RESEARCH NEEDS
FOR THE 33/50 PROGRAM
SOURCES AND PRODUCTION
CHARACTERISTICS AND RATES
Mercury (chemical symbol Hg) has been used since antiquity as a pigment and for
medicinal purposes. The primary source of mercury is the sulfide ore, cinnabar.
Mercury is also obtained in smaller quantities from ores containing mixed sulfides,
oxides, and chloride minerals, which are usually associated with base and precious
metals. Native or metallic mercury, is found in very small quantities in some ore
sites. Mercury is estimated to occur in concentrations of 10 to 1,000 ppb in the
earth's continental crust and 2,000 to 20,000 ppb in petroleum. By contrast, ore
grade materials typically contain 5,000,000 ppb (0.5%) mercury. Some early
methods for purification included leaching the ores in sodium sulfide and sodium
hydroxide solutions, or in a sodium hypochlorite solution. Today, sulfide ores are
retorted and liquid metallic mercury is condensed from the vapor.
Smaller amounts of mercury are produced from secondary sources, such as scrap
batteries, lamps, switches, dental amalgams, measuring devices, and control
instruments, and from laboratory and electrolytic refining wastes. Kirk and Othmer
(1979) provide the quantity of mercury used in these types of products.
World production of mercury peaked around 1971 with annual production in excess
of 10,000 metric tons; in 1978 production declined to about 6,000 metric tons (Kirk
and Othmer, 1979). Production of mercury in the United States in those two years
was 616 and 883 metric tons, respectively. This decline was due primarily to a
drop in price, mining of lower grade ores, a decrease in consumer use, an
increase in recycling, and curtailment of mining operations due to more stringent
environmental protection regulations. The standard unit of trade is the "flask,"
which weighs 76 pounds.
Mercury consumption was reported in about '200 plants in the United States in
1988. Prime virgin mercury accounted for 66% of the total; secondary mercury,
27%; and redistilled mercury, 7%. Mercury usage increases in the manufacture
of chlorine and caustic soda were reported in 1988. Other important uses include
the manufacture of wiring devices and switches, which have declined steadily in
the last decade, from 2,075 tons in 1984 to about 1,300 tons in 1990. Mercury
use in dry-cell batteries has declined steadily in recent years.
66
-------
MERCURY
The U.S. Bureau of Mines (1991) has approximated apparent consumption
patterns for mercury in 1990 as follows:
electrical and electronic devices 33%
chlorine and caustic soda production 33%
instrument, dental, paints, and other uses 34%
Some of the first modern uses of metallic mercury were as a fluid in the barometer
—Torricelli in 1643- and the thermometer— Fahrenheit in 1720. Both devices rely
on mercury's uniform volume expansion throughout its liquid range and its high
surface tension that prevents it from wetting or clinging to glass. Today, mercury
continues to be of technological value because of its unique properties that include
high electrical and thermal conductivity, and high thermal neutron capture cross
section, and its propensity to form amalgams, which it can do with almost every
metal except iron (and iron too at high temperatures). Mercury compounds are no
longer used as a biocide in interior latex paints but may still be used in some
exterior latex paints.
Although mercury was known to be toxic for many centuries, the level of health
hazard has come to light only since the 1970s. Metallic mercury, its vapor, and
many of its compounds are protoplasmic poisons, which are toxic to all forms of
life. Ingesting sufficient quantities, by mouth, through the skin, or by inhalation,
can cause severe neurological damage and fatality in humans (Budavari, 1989).
The alkyl organic compounds are the most toxic forms of mercury. Acute toxicity
from mercury poisoning has on occasion manifested itself in catastrophic events.
For example, 100 deaths or severe neurological damage resulted from consump-
tion of fish in Minamata, Japan, contaminated with methyl mercury and mercuric
chloride; another event in Iraq cause injuries from consumption of contaminated
rice. It is now known that some marine organisms can biologically methylate
inorganic mercury and concentrate it up to 3,000 times.
Table 8 shows the pollution prevention research needs for mercury.
67
-------
PREVENTION RESEARCH NEEDS
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-------
MERCURY
POLLUTION PREVENTION OPPORTUNITIES
AND SUPPORTING RESEARCH NEEDS
Batteries
Batteries make up the largest specific use of mercury, which in 1984 accounted
for more than half of the mercury consumption in the United States (Kirk and
Othmer, 1979). Mercury has historically been used to coat the zinc anode
(negative electrode) in nonrechargeable household batteries. A few examples of
these dry cell-type batteries are listed below:
Battery Type
Zinc-Carbon
Alkaline-Manganese Dioxide
Mercuric Oxide
Zinc-Silver Oxide
Carbon-Zinc Air
Size/Configuration
AAA, AA, C, D, 9V
AAA, AA, C, D, 9V
Button cells (hearing aids)
Button cells
Button cells (hearing aids and pagers)
Mercury is used to prevent the evolution of hydrogen gas from the battery, which
results from internal chemical reactions. Hydrogen may pressurize the cell and
cause internal leaking or explosion, although blowout valves are now installed at
the tips to minimize this possibility. In the alkaline-manganese battery, zinc anodic
material is added as a powder. In the past, 1 to 3% mercury was mixed with the
powdered zinc to form a mercury-zinc amalgam that will inhibit zinc oxidation
caused by chemical reactions with other components in the battery. The
proportion of mercury in the amalgam decreases the rate of oxidation.
Alternatives to mercury have been sought within the battery manufacturing
industry. Notable success has been found with some organo-silicate compounds.
Testing by Rayovac (Tillman, 1991) has shown that these compounds restrict H2
evolution. Results are listed below in order of increasing performance:
sodium dimethylsiloxane = polydimethylsiloxane
« phosphate functional silate
nonhydrolyzable silicone copolymer = polydimethylsiloxane-
polyoxyethylene copolymer
DC-193™ (proprietary compound)
The actual mechanism for restricting H2 evolution is not known with certainty.
Coating the zinc/mercury amalgam may form a physical barrier to diffusion, or it
may increase mercury's efficiency in preventing zinc oxidation. Note that mercury
is still used in this treatment, but smaller amounts are now needed. Batteries
manufactured in the 1960s contained up to 1.3% mercury, by total battery weight.
70
-------
MERCURY
An international standard set for implementation in 1992 calls for no more than
0.025% mercury.
Another development in mercury reduction in batteries has been reported by
Battery Technologies Inc. (BTI, Mississauga, Ontario) (Roy, 1991). In developing
a rechargeable alkaline zinc-manganese dioxide battery, they prepared "a cleaner,
more precise (electrochemical) system" than is used in conventional single-use
batteries. Their system claims to convert any hydrogen gas generated to water,
and requires less mercury in the process. The BTI battery contains organic and
other metallic inhibitors that perform the function normally assumed by mercury.
Improve efficiency of inhibitors. Improve
the performance characteristics of the material
used to coat zinc/mercury amalgams. Such
improvements should permit less mercury to
be used.
Search for new organic or metallic inhibi-
tors. Use a different method of preventing
zinc oxidation and subsequent H2 evolution
that does not involve zinc amalgamation with
mercury. Following the example of BTI, mer-
cury content should decrease to zero as the
process is improved.
Develop batteries that last longer. Extend
the lifetime of batteries so that they are dis-
posed of less often. This proposal is based on
the simple theory that a battery that lasts twice
as long should end up in a landfill half as
often.
Encourage use of rechargeable-type batter-
ies. Rechargeable batteries will provide up to
20 times longer service hours than convention-
al single-use batteries. This option would
translate into fewer batteries entering the
waste disposal cycle.
Catalysts
Mercury (HgCI2) is used as a catalyst primarily for the production of vinyl chloride
monomers (Ulrich, 1988, p. 73) and urethane foams (Oertel, 1985, p. 114). It is
also used to produce anthraquinone derivatives and other products. Discharges
Research needs. Research is needed to
verify whether organic coatings on Zn/Hg
amalgams work synergistically to improve the
efficiency of the amalgam in restricting H2
evolution.
Research needs. Research is needed to
explore new ways of inhibiting zinc oxidation,
or catalyzing H2 to form water in a manner that
does not diminish the lifetime of performance
of the battery.
Research needs. Research is, needed to
improve existing battery technology so that
batteries maintain a longer useful lifetime.
Research needs. Studies would first be con-
ducted to discern the expected level of con-
sumer participation in this pollution prevention
strategy.
71
-------
MERCURY
from plants that produce these substances are sources of mercury-containing
wastes. Old disposal areas may eventually require cleanup.
Change synthesis path to avoid the need of
a catalyst or use a nonhazardous catalyst.
Different combinations of chemical feedstocks
may allow preparations of the desired product
without the need of a catalyst.
Chlorine and Caustic Soda
.Research needs. Research is needed to
determine the requirements for specific reac-
tions and to identify test methods to measure
the purity, yield, and other requirements. Then
candidate reaction paths can be identified and
tested as alternatives for paths requiring lead
compounds as catalysts.
Production of chlorine gas and caustic soda accounts for the largest use of
mercury in the United States. The manufacturing process is also responsible for
the largest loss of mercury into the environment., One process uses mercury and
a following cathode in an electrolytic cell into which sodium chloride brine is intro-
duced. A current is applied to electrolytically oxidize chloride anions to form CI2
gas, which is collected at the anode, and an.alkali metal amalgam is formed with
the mercury cathode. The amalgam is then decomposed with water, to form
caustic soda (sodium hydroxide) and hydrogen and relatively pure mercury metal.
Although mercury metal is recycled back to the cell, large losses do occur in brine
purification muds and in wastewater treatment sludges. The brine sludge contains
small amounts of mercuric ions, mostly as the tetrachloro complex, HgCI22~.
The membrane cell is another method of producing caustic soda and one which
does" not use mercury. The membrane cell uses cation and anion selective semi-
permeable membranes to allow electrolytic separation of chlorine and caustic soda
from brine. The membrane cell has advantages over the mercury cell that include
lower operating voltage and higher efficiency, and it does not require the high capi-
tal investment in mercury.
Use membrane cells for caustic production.
Improve the performance of membrane cells
that do not require the use of mercury.
Switching Devices and Control Instruments
Research needs. Research is needed to
better implement electrolysis methods for the
conversion of sodium chloride to caustic soda
and chlorine.
Mercury is used in higlWIow-voItage mercury-arc rectifiers, oscillators, power
control switches for motors, phanatrons, thyratrons, ignitrons, reed switches, silent
switches, thermostats, and cathode tubes in radios, radar, and telecommunications
equipment.
72
-------
MERCURY
Mercury is also used in many medical and industrial instruments to control or
measure reactions and equipment functions. This list includes mostly metallic
mercury equipment, such as thermometers, manometers, barometers, the calomel
electrode, and other pressure-sensing devices, gauges, valves, seals, and
navigational controls.
Research needs. Research is needed to
explore what alternative methods exist for
replacing mercury instruments and to judge
whether they are economical to use.
Use alternative methods for sensing. There
are some situations where electronically con-
trolled devices can replace the role of mercury
in mechanical instruments. For example,
temperature can be detected using a thermo-
couple instead of a thermometer.
Electrical Lamps
Mercury vapor is used in both the low-pressure "fluorescent" lamp and high-
pressure mercury lamp. Fluorescent lamps are commonly used for indoor lighting,
whereas high-pressure mercury lamps are used for street lighting, industrial work
areas, aircraft hangers, and floodlighting. Other mercury-vapor lamps are used for
photographic purposes, including motion picture projection, and for heat therapy.
Use a different fluorescent gas in lamps. It
may be possible to use substances other than
mercury for fluorescent lighting.
Fungicides
Research needs. Research is needed to
explore the electronic molecular properties of
nonhazardous substances for use in fluores-
cent lamps.
Mercury is used primarily in latex paint as a fungicide to prevent mildew of the
applied coating and as a bactericide or preservative to inhibit bacterial attack
during storage. The most commonly used fungicides are phenylmercuric acetate
(PMA) and phenylmercuric oleate. Alkyl mercury compounds are no longer
produced, due to their extreme toxicity and long lifetimes.
Mercury was used as a slimicide in the paper and pulp industry, but its use has
decreased considerably since 1970.
Replace fungicide in paint with non-mercu-
ry alternative. Find alternative bactericides
and preservatives that are compatible with
exterior latex paint to extend storage life.
Research needs. Search known bactericides
and preservatives for suitable alternatives to
PMA and phenylmercuric oleate.
73
-------
MERCURY
REFERENCES FOR MERCURY
Budavari, S. (Ed.). 1989. The Merck Index, 11th ed., Merck & Co., Inc., Rahway,
NJ, p. 927.
Conner, J.R. 1990. Chemical Fixation and Solidification of Hazardous Wastes,
Van Nostrand Reinhold, pp. 140-148. . : .
Kirk, R., and D. Othmer. 1979. Encyclopedia of Chemical Technology, 3rd ed.,
John Wiley & Sons, New York, NY, .
Licis, Ivars J., Herbert S. Skovronek, and Marvin Drabkin. 1991. 'jnddstrial
Pollution Prevention Opportunities of the 1990s. EPA/600/8-91/052, Task 0-9,
Contract 68-C8-0062. Risk Reduction Engineering Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio, August.
Nelson, K.E. 1990. "Use These Ideas to Cut Waste." Hydrocarbon Processing,
March. '
Oertel, G., Ed. 1985. Polyurethane Handbook. Macmillan, New York.
Roy, K.A. 1991. "Mercury-Free Products Charge Battery Market." Hazmat World,
4:70-71.
Tillman, J.W. 1991. Achievements in Source Reduction and Recycling for Ten
Industries in the United States. EPA/600/2-91/051, U.S. Environmental Protection
Agency, September, pp. 20-22.
Ulrich, Henri. 1988. Raw Materials for Industrial Polymers. Oxford University
Press, Mew York.
U.S. Bureau of Mines. 1991. Mineral Commodity Summaries.
74
-------
POLLUTION PREVENTION RESEARCH NEEDS FOR
ELEVEN TRI ORGANIC CHEMICAL GROUPS
SOURCES AND PRODUCTION
CHARACTERISTICS AND RATES
Eleven organic chemicals have been selected from the Toxics Release Inventory
(TRI) by EPA as target chemicals for the 33/50 Program. These include six
chlorinated compounds (i.e., methylene chloride, chloroform, carbon tetrachloride,
1,1,1 -trichloroethane, trichloroethylene, and tetrachloroethylene) and five
nonchlorinated compounds (i.e., methyl ethyl ketone, methyl isobutyl ketone,
benzene, toluene, and xylenes).
Methylene chloride, chloroform, and carbon tetrachloride are chlorinated methanes.
Methylene chloride, also known as dichloromethane, is a colorless liquid with a
sweet, penetrating odor. It is manufactured primarily from the chlorination of
methane (Budavari, 1989). Of the 452 million pounds used in 1988, paint stripping
accounted for 28% of the consumption (Chemical Profile, 1989). Methylene
chloride is also used for vapor degreasing (8.8% [Chemical Profile, 1989] or 20%
[Ulrich, 1988]), cold cleaning, and food processing, as well as in the production of
aerosols (20% [Chemical Profile, 1989] or 9.7% [Wolf et al., 1991 ]), urethane foam
(10% [Chemical Profile, 1989] or 11.2% [Wolf et al., 1991 ]), adhesives, pesticides,
electronics, Pharmaceuticals, and textiles. Methylene chloride accounted for
10.9%ofthe 1988 TRI top 50 four-digit Standard Industrial Category (SIC) release
and transfer (TRI R&T) (see Table 3). '
Chloroform is a volatile, colorless liquid with a pleasant, sweet odor. It is
manufactured from chlorination of methane or from reaction of acetone and
bleaching powder with the addition of sulfuric acid. According to Chemical Profile
(1989), chloroform consumption in 1989 totaled 484 million pounds. Of this, 90%
was used for CFC 22 synthesis, of which 70% was used as refrigerants and the
remainder in the production of fluoropolymers. Chloroform is also used for
industrial degreasing and as a solvent for fats, oils, rubber, alkaloids, waxes, and
resins (Budavari, 1989). Chloroform was once used as an anesthetic and in cough
syrups and toothpastes; these uses have been restricted because of environmental
and health concerns. Chloroform is also a chlorination by-product of some
industrial processes, such as paper manufacturing. Chloroform accounted for only
a small fraction of the 1988 TRI R&T, i.e., 1.9% (see Table 3).
Carbon tetrachloride is a colorless, clear, and sweet-smelling liquid. It is produced
primarily by chlorination of either methane or carbon disulfide in the presence of
a catalyst (Budavari, 1989). The consumption in 1988 was 761 million pounds.
Of this, 91 % of carbon tetrachloride was used for the production of chlorofluorocar-
75
-------
ELEVEN TRI CHEMICALS
bons (CF:Cs) 11 and 12 (Chemical Profile, 1989). It is also used in the production
of dyes, drugs, lubricants, and semiconductors. Carbon tetrachloride has been
widely used as a household and industrial cleaning solvent and as a grain
fumigant. These uses have been discontinued due to health concerns. As shown
in Table 3, carbon tetrachloride accounted for about 0.4% of the 1988 TRI R&T.
The remaining three chlorinated compounds— 1,1,1-trichloroethane, trichloroethyl-
ene, and tetrachloroethylene — are chlorinated C2 chemicals. The basic
feedstocks for these chemicals are ethylene, ethane, and propane. Chlorination
of an intermediate — ethylene dichloride — yields a mixture of trichloroethylene and
tetrachloroethylene. Chlorination of ethane yields trichloroethane, and chlorination
of propane produces mixtures of tetrachloroethylene and carbon tetrachloride.
The first, 1,1,1-trichloroethane— also known as methyl chloroform or TCA — is a
nonflammable liquid with a pleasant odor. In 1988, about 650 million pounds of
TCA were used (Wolf et al., 1991; Chemical Profile, 1989), 52% of which was
used in vapor degreasing and cold cleaning. TCA is also used in aerosol (13.5%),
adhesive (8.7%), and coating (5.8%) formulations. TCA can be used as a
photoresist developer and for printed circuit board defluxing and synthesis of
hydrochlorofluorocarbon (HCFC). A smaller amount is used in textile processing,
pesticide formulations, and flexible foam. TCA accounted for 13.5% of the 1988
TRI R&T (see Table 3).
Trichloroethylene (TCE) is a clear, volatile liquid with a sweet odor resembling that
of chloroform. Its consumption in 1988 totaled about 160 million pounds (Chemical
Profile, 1989; Wolf et al., 1991). TCE is used primarily in cleaning applications
such as vapor degreasing and cold cleaning of fabricated metal parts (85% [Wolf
et al., 1991; Chemical Profile, 1989]). Some TCE is used in the electronics and
textile industries, and as a chain terminator in the production of polyvinyl chloride.
TCE accounted for about 4% of the 1988 TRI R&T (see Table 3).
Tetrachloroethylene, also known as perchloroethylene or PERC, is a colorless
liquid with an ethereal odor. The reported consumption of PERC in 1988 was 568
million pounds (Wolf et al., 1991), 46.5% (or 53% [Chemical Profile, 1986]) of
which was used in dry cleaning and textile processing. PERC is also used in
metal degreasing and cold cleaning (10% [Chemical Profile, 1986]), and as a
solvent and a chemical intermediate in producing CFC-113 and CFC-114 (Wolf et
al., 1991). PERC accounted for 2.7% of the 1988 TRI R&T (see Table 3).
Two ketones are included in the TRI target chemicals: methyl ethyl ketone and
methyl isobutyl ketone. Methyl ethyl ketone (MEK) is a colorless, flammable liquid
with an acetone-like odor. It is manufactured by dehydration of 2-butanol or by
catalytic oxidation of n-butenes (Budavari, Inc., 1989). Its 1989 consumption
totaled 429 million pounds. As summarized in Chemical Profile (1990), MEK is
used primarily as a solvent for coatings (51%) and in adhesives (11%), magnetic
76
-------
ELEVEN TRI CHEMICALS
tapes (8%), and printing inks (3%). A smaller amount is used as an intermediate
for a flavoring ingredient and as a solvent in nail enamel. MEK accounted for
11.3% of the 1988 TRI R&T (see Table 3).
Methyl isobutyl ketone (MIBK) is another colorless, flammable liquid with a
pleasant, honey-like odor. It is derived by mild hydrogenation of mesityl oxide (4-
methyl-3-penten-2-one). Its 1989 consumption was 156 million pounds (Chemical
Profile, 1990). MIBK is used primarily as a solvent for protective coatings (60%
[Chemical Profile, 1990) or 71% [Lawler, 1977]); a process solvent for adhesives,
inks, and Pharmaceuticals (10% [Chemical Profile, 1990]); in chemical production
including rubber processing (10% [Chemical Profile, 1990]); and in the extraction
of rare metals such as uranium from fission products (Sax and Lewis, 1987). It is
used as a raw material for manufacturing antioxidants to improve the shelf life of
some chemicals (Reilly, 1990). MIBK represented about 3% of the 1988 TRI R&T
(see Table 3). : .
t . " . ' ' . .
Benzene, toluene, and xylenes, often known collectively as BTX, are the basic
feedstocks for many aromatic chemicals and polymers. Benzene is a volatile,
colorless, and flammable liquid hydrocarbon with a slightly sweet aromatic odor.
It exists naturally in crude oil and coal. It is manufactured or extracted in very
large quantities in oil refining and coal coking (Kirk and Othmer, 1978). It is also
produced from hydrodealkylation of toluene or as a by-product from steel
production. In 1989, its consumption totaled 1,785 million gallons (Chemical
Profile, 1990). Benzene is used primarily as a chemical raw material in the
synthesis of ethylbenzene/styrene (53% [ChemicalProfile, 1990]); cumene/phenol
(21%); cyclohexane (12%); nitrobenzene/aniline (5%); detergent alkylate (3%);
chlorobenzenes; and other products used in the production of drugs, dyes,
insecticides, and plastics (Kirk and Othmer, 1978). Benzene has also been used
in smaller amounts in gasoline and as a solvent and degreasing agent (Reilly,
1990), but these uses have been greatly reduced because of environmental and
health concerns. Benzene represented 2.4% of the 1988 TRI R&T (see Table 3).
Toluene is a colorless, mobile liquid with a distinctive aromatic odor somewhat
milder than that of benzene. It occurs naturally in crude oil, and 87% of toluene
is produced by catalytic reforming of petroleum and subsequent fractional
distillation of the aromatics (Sax and Lewis, 1987; Kirk and Othmer, 1983).
(Toluene is usually produced along with benzene, xylenes, and C9 aromatics.)
Toluene may be separated from pyrolysis of gasoline produced in steam crackers
during the manufacture of ethylene and propylene.. It is also a by-product of
styrene manufacturing: Consumption of toluene totaled'5,589 million pounds in
1984 (Ulrich, 1988). About 90% of the toluene generated by catalytic reforming
is used as a blending component in gasoline. Toluene is an important feedstock
for benzene manufacturing and a solvent in paints, coatings, adhesives, inks,
Pharmaceuticals, and other formulated products utilizing a solvent carrier.
However, the use of toluene as a solvent in surface coatings is declining because
77
-------
ELEVEN TRI CHEMICALS
of various environmental and health regulations. Toluene represented about one
quarter of the 1988 TRI R&T (see Table 3).
Xylene is a colorless liquid with a slightly sweet aromatic odor. Its three isomers,
o.-xylene, nvxylene, and jD-xylene, coexist with ethylbenzene, and the mixture is
usually called "mixed xylenes" (Kirk and Othmer, 1983). Mixed xylenes are
derived mainly from catalytic reforming of petroleum (94.5%). Smaller quantities
are produced from pyrolysis of gasoline (4.4%). Individual isomers are separated
from mixed xylenes in oil refineries or petrochemical operations. In 1984, usages
totalled 688, 90, and 2068 million pounds for o.-xylene, rn-xylene, and £-xylene,
respectively (Ulrich, 1988). All three xylene isomers are important feedstocks for
industrial polymers: o.-xylene is mainly converted to phthalic anhydride, which is
used for the synthesis of unsaturated polyester resins; jD-xylene is oxidized to
terephthalic acid and dimethyl terephthalate, which are the basic building blocks
for synthetic polyester fibers and aramid fibers; ni-xylene is converted to
isophthalic acid for the manufacture of aramid fibers. Smaller quantities of xylenes
are used as a solvent in paints, coatings, and agricultural sprays (Reilly,-1990).
Xylenes accounted for 14.4% of the 1988 TRI R&T (see Table 3).
The pollution prevention approaches and research needs for the eleven organic
chemicals are summarized in Table 9 and are outlined in the text following the
table. Several points regarding the preparation of the table and the text are noted
in the following:
« This document is prepared according to specific functions
and uses of these chemicals rather than chemical classes.
This is because chemicals in different chemical classes may
be used for one specific application. For example, both
chlorinated and nonchlorinated solvents are used for
protective coatings and as cleaning solvents for printing.
Most chlorinated methanes and chlorinated C2 chemicals
are used for vapor degreasing, cold cleaning, and paint
stripping for metal surface preparation.
• The pollution prevention research needs are identified
based on the technical information available in the public
domain. Certain industries, such as chemical manufacturing
and petroleum refining, do not provide information regarding
specific pollution prevention techniques because of the
diversity and specificity of the industries and the desire to
guard confidential business information. Therefore, this
document contains only limited discussion .about the
research needs for these industries.
• The research needs identified are applicable to most of the
12 two-digit SIC codes that are primarily responsible for the
release of the target chemicals.
78
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ELEVEN TRI CHEMICALS
POLLUTION PREVENTION OPPORTUNITIES
AND SUPPORTING RESEARCH NEEDS
Paint Stripping
Paints and organic coatings are applied to surfaces of various substrates to
enhance corrosion resistance and/or improve appearance. Often coatings need
to be removed as part of the manufacturing operations or to enable maintenance
or repair. In aerospace and aviation industries, coatings must be removed to allow
inspection of underlying substrates for cracks and structural defects. Conventional
paint stripping technologies use chemical or physical methods or a combination
of both to remove paints. Chemical methods rely on the solvency, oxidizing, or
swelling properties of the applied stripper to destroy coatings. Physical methods
use abrasives, such as sandblasting, to scrape away paints. The chemical
strippers most commonly used include chlorinated and aromatic solvents (e.g.,
methylene chloride and phenol-based solvents), caustic and acidic solutions, and
molten salt.
Paint stripping operations generate large quantities of spent solvents and solvent-
bearing wastewaters and solid-phase wastes. The operations also result in air,
emissibns through volatilization during storage, fugitive losses during use, and
direct ventilation of fumes.
Avoid solvent use. Several "clean" technolo-
gies that are either commercially available or
are being developed, eliminate the use of haz-
ardous solvents. These include plastic media
blasting (PMB), bicarbonate of soda blasting,
liquid nitrogen and carbon dioxide pellet cryo-
genic blasting, wheat starch blasting, ice crys-
tal blasting, high-pressure waterjet stripping,
and laser or flashlamp heating. These technol-
ogies remove coatings by using abrasive
and/or impact action, extreme cold to embrittle
coatings, or heal: input to burn coatings.
PMB and bicarbonate of soda blasting use
nontoxic plastic beads and sodium bicarbon-
ate, respectively, as stripping media for coating
removal. These processes do not generate
noxious air emissions, but the disposal of the
spent media could be a problem because they
contain paint residues that often consist of
hazardous metals or unreacted resins. More-
over, these processes are noisy and may
generate toxic airborne particulates. The cryo-
Research needs. PMB is a more mature
technology, but there are still areas that war-
rant future research. These may include long-
term structural effects, PMB-induced substrate
damage (especially to composites), and the
effects of PMB on the resistance of different
substrates and substrate thickness to crack
growth (Cundiff et al,, 1989). The cleaning
requirements on different materials (e.g., clad
aluminum, titanium, magnesium, stainless
steel, and composites) after PMB (Galiiher,
1989) and the effects of PMB on substrate
inspection need further investigation. The
potential for corrosion and localized paint
failure also needs further study.
For bicarbonate of soda blasting, studies need
to be done to determine the potential for sub-
strate damage on sensitive materials, the
degree of masking of fatigue cracks, the
effects of residual sodium bicarbonate and its
by-products on the substrate when exposed to
88
-------
ELEVEN TRI CHEMICALS
genie blasting uses liquid nitrogen or carbon
dioxide pellets to embrittle coatings and subse-
quently remove them by PMB or carbon diox-
ide pellets. Cryogenic strippings result in a
low-volume solid waste stream but still consist-
ing of paint chips and spent plastic media.
Wheat starch blasting uses particles of nontox-
ic, biodegradable wheat starch to remove
coating. However, the fractured particles
become less effective in coating removal, and
the dust generated increases the explosion
hazard. Ice crystal blasting results in a small
volume of waste because ice crystals melt and
evaporate. On the contrary, high-pressure
waterjet stripping produces a large volume of
aqueous waste. Laser and flashlamp coating
removal use the thermal energy input from a
laser beam and a xenon flashlamp, respective-
ly. The last five technologies are mainly in the
advanced pilot testing stage.
Use alternative stripping agents. Alternative
stripping agents with less-toxic or nontoxic
properties may be available to replace the
hazardous stripping solvents. These stripping
agents will be used to remove coatings from
workpieces for which other mechanical strip-
ping methods are not suitable.
Source reduction and recycling. There may
be ways to extend solvent life and/or reduce
solvent emissions to air, wastewater and/or
solid-phase wastes.
operating temperature and humidity conditions,
and the optimal process conditions for thin-
skinned aluminum aerospace structures. The
handling and disposal of the wastes also need
to be evaluated.
Research is needed to determine the effects of
liquid nitrogen cryogenic blasting on aircraft
substrates and adhesive bonding materials, the
long-term effects of the rapid changes in
temperature on substrates, and the generation
of toxic airborne particulates in the workplace.
For carbon dioxide pellet blasting, further
testing must be done on fatigue life degrada-
tion, crack growth potential, and the possibility
of inducing microcracks in composite materi-
als. Further optimization of the process is also
needed for a wide range of substrates, includ-
ing pellet size, shape, and hardness; pressure;
impingement angle; and stand-off distance
(Larson, 1990, ivey, 1990).
Research is needed to identify and validate
other new and emerging nonsolvent paint
stripping methods. Studies should focus on
the assessment of method effectiveness, the
ability of achieving satisfactory work products,
optimization of the process conditions, the
benefits of waste reduction and pollution
prevention, and the economics.
Research needs. Research is needed to
identify less-toxic or nontoxic stripping agents
for workpieces that cannot be stripped using
the nonsolvent methods. The effectiveness of
the stripping agents, the quality of the work
products, the waste reduction potential, and
the economics are the major items to be
examined.
Research needs. When an alternative does
not exist, source reduction and recycling may
be used to extend solvent life and/or reduce
solvent emissions (U.S. EPA, 1992a). System-
atic studies are needed to identify methods to
89
-------
ELEVEN TR1 CHEMICALS
reduce solvent usage, opportunities to elimi-
nate specific work steps, methods to maximize
stripping efficiency, procedures to segregate
stripping wastes, methods to reuse or regener-
ate solvents, and opportunities to recycle
stripping solvents.
Solvent Cleaning/Degreasing
Solvent cleaning/degreasing involves some of the most important steps during the
surface preparation and finishing of the fabricated metal products. Clean-
ing/degreasing is performed to remove adsorbed substances that interfere with
process performance or that affect product appearance. In metal finishing, the
materials to be removed (usually called "soils") from the surface of a workpiece
may include lubricants, cutting oils, polishing and buffing compounds, and oils for
quenching and rust prevention. Other soils that may be encountered include rosin,
solderfluxes, paints, adhesives, inks, toners, asphalt, particulates, and fingerprints.
Chlorinated solvents have been widely used to remove organic contaminants. The
solvents most commonly used are trichloroethylene (TCE), 1,1,1-trichloroethane
(TCA), CFC-113, perchloroethylene (PERC), and methylene chloride. The
classical cleaning processes involve vapor degreasing and cold cleaning. Vapor
degreasing uses solvent vapor to contact the suspended soiled parts, dissolving
the soil and flushing the liquid/soil mixture back into the hot liquid. TCE was once
used as the prime vapor degreasing solvent, but because of its toxicity, its use has
been largely replaced by TCA and CFC-113. Cold cleaning is usually performed
in a tank containing TCA and other cleaning solvents at room temperature. The
performance of the cold cleaning solvent usually degrades with use as it becomes
loaded with dissolved materials.
The vapor degreasing and cold cleaning operations are major sources of emission
of the chlorinated solvents. Air emissions through volatilization during storage,
fugitive losses during use, and direct ventilation of fumes accounted for more than
80% of the 1988 TRI R&T (see Table 3). The degreasing and cold cleaning also
produce large quantities of solvent-bearing wastewater and solid-phase wastes.
Avoid chlorinated solvents use by using
alternative cleaning solutions. Nonhazard-
ous or less-hazardous cleaning solutions can
be used to replace the hazardous chlorinated
solvents. Examples include aqueous cleaners,
semiaqueous cleaners, aliphatic hydrocarbons,
HCFCs, and N-methyl-2-pyrrolidone. Aqueous
cleaners are made up of several classes of
chemical components including builders,
Research needs. Before using an alternative
cleaning solution, research is needed to identi-
fy and classify cleaners and soils, establish
cleaner evaluation criteria, optimize cleaner
performance, and determine its ability to
conform with specifications and production
processes. In general, an extensive industrial
and/or literature survey must be conducted to
identify candidate cleaners that are suitable for
90
-------
ELEVEN TRI CHEMJCALS
surfactants, emulsifiers, deflocculants, saponifi-
ers, sequestering agents, and/or other addi-
tives. Some aqueous cleaners have been in
constant use by metal finishers, but the effects
of various aqueous cleaners on different
substrates have not been fully characterized.
The drying of the cleaned parts also poses a
challenge.
The semiaquepus cleaners are made up of
biodegradable hydrocarbon solvents and
water-based surfactants that form an emulsion
upon mixing. The hydrocarbons used are
usually terpenes (e.g., d-limonene, para-ment-
hadienes, and terpene alcohols) and glycol
ethers. The,«rnajor uncertainty about the
semiaqueous cleaners is their ability to meet
biodegradability and toxicity requirements for
economic recycling and disposal.
Aliphatic hydrocarbons include petroleum
fractions such as mineral spirits, kerosene,
white spirits, and naphtha. This technology
becomes a viable alternative when water
contact with the workpieces is undesirable.
The chronic toxicity and smog production
potential are among the subjects of concern.
Other chemicals that may be beneficial as a
replacement solvent include alcohol, esters,
glycol ethers, acetone, vegetable oils, and fatty
acids. Many of these solvents have been used
for some time.
In addition, supercritical fluid cleaning, carbon
dioxide snow, absorbent cleaning, vacuum
degreasing, and cold catalysis have also been
suggested as new/emerging technologies to
replace solvent cleaning and degreasing. All
of these technologies need to be tested to
determine their cleaning efficiency and their
effects on substrates.
Use alternative cleaning processes. It is
often possible to use alternative cleaning
the kind of soils (and substrates) to be
cleaned. The cleaner evaluation criteria may
include cleaning efficiency of each candidate
cleaner, etch rate, corrosion effects, and
staining on substrates. Adequate evaluation
methods and techniques must b.e established
for these evaluations and the optimization of
the cleaner performance. The economics of
the alternative cleaners must also be assessed
before they can be fully accepted by industries.
When using an alternative cleaning solution, it
is important to monitor emissions of cleaner
components to workplaces and the environ-
ment and the associated chronic toxicity. It is
also highly desirable to develop methods that
extend solution life and reduce emissions.
When considering solution regeneration and
recycling, one must examine the cleaner
performance both before and after the solution
regeneration.
Research needs. The major research need is
to identify and validate new process technolo-
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ELEVEN TRI CHEMICALS
processes to reduce or eliminate the need to
use the hazardous chlorinated solvents or to
employ technologies that eliminate the need
for cleaning. Several cleaning processes are
commercially available, including ultrasonic
cleaning, automated aqueous washing, aque-
ous power washing, no-clean flux (low solids
fluxes), no-clean solder. Ultrasonic cleaning
uses conventional technologies, but tests must
be performed to obtain the optimum combina-
tion of cleaning solution concentration and
cavitation level. Automated aqueous washing
and aqueous power washing combine an inno-
vative process technology with the use of
aqueous solutions. However, some delicate or
difficult-to-clean parts may not be cleaned.
No-clean flux and non-clean solder result in
little or no visible residue on the integrated
circuit boards; therefore, traditional flux may be
eliminated. But even limited residues are
sometimes not acceptable to many military
specifications.
Other examples of process changes include
surface cleaning by laser ablation, fluxless
soldering, replacement of tin-lead joints, and
temporary vapor storage (TVS). Research on
TVS is being conducted based on the fact that
it may be impossible to totally eliminate chlori-
nated solvent usage. Because regeneration of
the carbon adsorbers that trap fugitive vapors
from cleaning and degreasing operations often
poses problems in terms of the operational
efficiency and economics, systems such as
TVS (Hickman and Goltz, 1991) do provide
attractive features — utilizing an air lock and
airtight equipment to allow temporary storage
of solvent vapors from a solvent source and to
return the vapors for reuse.
Source reduction and recycling. When
chlorinated solvents must be used, there may
be ways to extend solvent life and/or reduce
solvent emissions to air, wastewater, and/or
solid-phase wastes.
gies that could either reduce or eliminate the
use of hazardous solvents or eliminate totally
cleaning requirements during the fabrication/
manufacturing processes. The process chang-
es may involve the cleaning/degreasing or
even the manufacturing processes.
Research needs. When an alternative does
not exist, source reduction and recycling may
be used to extend solvent life and/or reduce
solvent emissions. Studies are needed to
identify methods to reduce solvent usage,
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ELEVEN TRI CHEMICALS
opportunities to eliminate specific work steps,
methods to maximize cleaning efficiency,
procedures to segregate stripping wastes,
methods to reuse or regenerate solvents, and
opportunities to recycle cleaning solvents.
Solvent for Coatings
Paints and other coatings are applied to the surface of various substrates primarily
to improve appearance and to resist corrosion. The substrates include sheet steel,
plastic composites, stainless steel, aluminum, titanium, and wood. Examples of
the industries applying coatings to these substrates include manufacturers of
automobiles, aircraft, appliances, and wood products. Classical organic coating
materials are dilute solutions of organic resins (e.g., alkyd, polyester, epoxy,
polyurethane, acrylic, vinyl, and other resins); organic or inorganic (e.g., Cd, Cr,
and Pb) coloring agents; and extenders dissolved in volatile organic solvents. The
organic solvents, such as MEK, M1BK, benzene, toluene, and xylene, provide
solvency, surface tension, and other properties to allow application of coating
materials on substrate surfaces. The coating processes result in solvent waste,
paint sludge wastes, paint-bearing wastewaters, and paint solvent emissions.
Paint cleanup operations may contribute to the release of chlorinated solvents,
such as carbon tetrachloride, methylene chloride, TCA, and PERC, and solid- and
liquid-phase wastes from equipment washing, paint application emissions control
devices, disposal materials used to contain paint overspray, and discarded paint
materials.
Use alternative coating methods involving
little or no volatile organic solvents. There
may be ways to apply coatings without the use
of volatile organic solvents. Examples include
100% dry resin formulations (powder coating),
100% reactive liquids (without any volatile
components), water-dispersed or water-soluble
polymer systems (water-based coating), or
high solids polymer systems with reduced
levels of organic solvents (high solids coating).
In powder coating, a coating film is formed by
applying either thermoplastic or thermosetting
powders on the substrate surfaces and, subse-
quently, melting the powders in a fluidized bed
or by .electrostatic spray. High solids coatings
use a higher concentration of solids with a
lower concentration of volatile organic solvents,
thus lowering fugitive solvent releases. Water-
based coatings use water to replace or supple-
Research needs. Research is needed to
identify new coating methods that eliminate the
use of hazardous volatile organic solvents. It
is also needed to determine the performance
requirements for these new coating methods
and to identify test methods to measure the
performance with respect to these standards.
The candidate methods can then be identified
and tested as alternatives for coating.
For the existing technologies, studies are
needed to improve the quality of work prod-
ucts, optimize the processes, and identify
effects on human health and the environment.
For example, for powder coatings, research is
needed to develop methods to apply thinner
coatings particularly to complex-shaped or
nonconductive substrates. For high solids
coatings, studies are needed to identify types
93
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ELEVEN TRI CHEMICALS
ment organic solvents. Ultraviolet radiation-
cured coatings use high-intensity UV light to
initiate free radical crosslinking of acrylate
oligomers and prepolymers, thus eliminating
solvent use and reducing paint waste. Several
other technologies have also emerged as
possible alternatives, including electron beam-
cured coatings, radiation-induced thermally
cured coatings, two-component reactive liquid
coatings, water-based temporary protective
coatings, vapor permeation- or injection-cured
coatings, and supercritical carbon dioxide as
solvent.
Source reduction and recycling. Methods
may be available to reduce the release of
volatile organic solvents through, for example,
the use of new/modified equipment and pro-
cesses and/or the recovery of the solvents
from overspray. These pollution prevention
approaches are especially useful for smaller
size paint shops.
of formulations that provide good coating
adhesion, flexibility, and impact resistance
while maintaining coating flexibility. Methods
to optimize pot life versus curing time are also
needed. Because high solids coatings only
reduce the amount of organic solvents in
coating formulations, they may be considered
only as near-term replacements for convention-
al coatings. In water-based coatings, studies
are needed to establish compatibility with
metal substrates and to address concerns over
corrosion. Future work is also needed to
develop low-cost cleaning methods for a
cleaner surface for water-based coatings. UV-
cured coatings need further development for
more widespread future use. The specific
areas are listed in Table 9.
Research needs. Research is needed to
develop equipment and processes that reduce
the release of volatile organic solvents. Exam-
ples include high-volume/low-pressure spray
guns that replace the airless guns and pro-
cesses incorporating prepainted automotive
parts before assembly (Lietzke, 1992). ReT
search is also needed to develop methods that
recover volatile organic solvents from over-
spray.
Dry Cleaning
Dry cleaning has been extensively used for the cleaning of fabrics. More than
70% of the dry cleaning is carried out with chlorinated hydrocarbons, including
PERC, TCE, TCA, carbon tetrachloride, and fluorinated chlorohydrocarbons,
among which PERC is the most widely used dry-cleaning solvent. Dry-cleaning
washers usually consist of a metal shell and a rotatable perforated inner cylinder
or wheel. The shell is a container for solvent, whereas the wheel holds the
garment load. The spent solvents are purified by distillation or by activated char-
coal and fatty acid-adsorbing sweetener powders. The solvent vapors are
removed by a carbon adsorber, and the adsorbed solvent can be recovered by
passing low-pressure steam through the adsorber.
Use an alternative solvent. It may be possi-
ble to use an alternative solvent to achieve
Research needs. Research is needed to
determine the performance requirements and
94
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cleaning results similar to those by PERC and
other hazardous solvents.
Use processes and equipment that elimi-
nate solvent emissions or use resource
recovery and recycling.. If an alternative
solvent is not available, it may be possible to
develop processes and equipment that com-
pletely eliminate solvent emissions. It is also
possible to recycle the spent solvents and
recover fugitive vapors.
Blending Components in Gasoline
ELEVEN TRJ CHEMICALS
to identify test methods to measure the perfor-
mance with respective to those standards.
The candidate solvents can then be identified
and tested as alternatives for dry cleaning.
Research needs. Technologies to achieve
the pollution prevention goals are being devel-
oped. For example, the dry-cleaning industry
has developed a dry-to-dry process to replace
the old transfer method to handle the washed
garment loads. However, research is needed
to improve solvent recovery efficiency, reduce
cost, and reduce worker exposure.
Toluene and some benzene have been used as blending components in gasoline,
particularly in unleaded premium gasolines. As a blending component in
automotive fuels, toluene and benzene have several advantages, including a high
octane number, relatively low volatility, and the tendency to reduce engine starting
difficulties (Kirk"and Othmer, 1983).
Use alternative blending chemicals. It may
be possible to use an alternative blending
chemical.
Improve fuel-handling practices. Devices
and equipment may be developed to eliminate
or reduce fugitive emissions of gasoline during
automobile and household equipment refuel-
ing.
Emissions from Petroleum Refining
and Related Industries
Research needs. Research is needed to
identify alternative blending chemicals that will
provide an adequate octane number, relatively
low volatility, and other desirable chemical
properties. The performance of the chemicals
will have to be evaluated for widespread use.
Research needs. Research is needed to
develop new gasoline dispensing nozzles,
automobile and household equipment fuel
intake devices, and household gas storage
tanks.
The primary emissions from petroleum refining and related industries are benzene,
toluene, and xylene (U.S. EPA, 1992b). The individual process units responsible
for these emissions include distillation, cat cracking, coking, and maintenance
operation. The distillation process separates the crude oil components at
atmospheric or reduced pressure by heating to temperatures of about 500°F and
subsequent condensing of the fractions by cooling. Cat cracking breaks down
larger, heavier, more complex hydrocarbon molecules into simpler and lighter
95
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ELEVEN TRI CHEMICALS
molecules using controlled heat and pressure with catalysts. The coking process
thermally decomposes heavier crude oil fractions to produce a mixture of lighter
oils and petroleum coke. As for the chemical manufacturing industry, information
relating to pollution prevention is not readily available.
Systems analysis to reduce waste. The
Petroleum Environmental Research Forum
(PERF), established in 1986 as a cooperative
agreement among 24 petroleum companies,
stimulates cooperative research for developing
new environmental technology for the petro-
leum industry. Some of PERF's research
programs and proposals reflect current re-
search needs in the petroleum refining indus-
try.
Improve source reduction and recycling
practices to control emissions. Petroleum
refining can result in various types of wastes
and air emissions. It is important to identify
the source of the waste before various source
reduction and recycling techniques may be
applied. The techniques to be used may
include controlling fugitive emissions, source
reduction and recycling of solid wastes, recy-
cling process waters, and employing responsi-
ble maintenance practices.
Research needs. Research needs as reflect-
ed by the PERF research projects and propos-
als include auto fuel emission screening,
preheating catalyst to reduce auto emissions,
microbial control using dilute halogen concen-
trations, spent caustic management, spent
fluidized bed catalytic cracking unit (FCCU)
catalyst management, oily emulsion formation
and control, and valve fugitive emission reduc-
tion.
Research needs. Research is needed to
identify the source of the waste in each of the
refining processes. Specific methods and
techniques need to be identified to control
fugitive emissions from sources such as crude
oil and product storage tanks, coker, barge
loading, etc. Methods also need to be identi-
fied/developed to achieve source reduction and
recycling of solid wastes and process waters.
Some areas of concern include recycling
hydrocarbon-bearing sludges from API separa-
tor to coking operation, recycling wastewater
treatment plant sludge to coking operation, and
recycling water used to cool and cut coke
products.
Emissions from Primary Metal
Smelting and Refining
The major pollutants from the primary metal industry are benzene, toluene, and
xylenes. These pollutants are produced primarily from heating coal in high-
temperature coke ovens during coking operations. The coke oven gas is
processed through recovery units to separate saleable by-products (e.g., benzene,
toluene, and xylenes) and is then used as fuel. During cast or mold making,
toluene and xylenes are used as mold washcoats. During hydrometallurgical
refining, solvents can be used as extractants to recover metals from ores through
leaching. The primary metal industry generates high-volume wastes including
slags, off-gases, and process wastewater at all primary and secondary metal
96
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ELEVEN TRI CHEMICALS
smelting operations. The primary metal industry is a major source of TRI R&T
(See Table 3).
Control release of organics in metal smelt-
ing and refining. For the primary metal
industry, source reduction is a difficult task
because all the chemicals of concern (except
cyanide) come from the raw materials. Im-
proved process control and equipment modifi-
cation can decrease the amount or concentra-
tion of the VOC emissions, but do not entirely
eliminate them. Changes in basic smelting
and refining processes hold more potential to
eliminate the wastes (U.S. EPA, 1992c).
Research needs. Research is needed to
assess the impact of basic process changes
on metal smelting and refining. Systematic
studies must be carried out to determine the
source of the waste and to develop new pro-
cesses that replace the existing ones. For
example, research is under way to develop
direct iron and steelmaking processes that turn
iron ore, coal, and limestone directly into iron
or steel in one vessel, thus eliminating the
need for coke ovens and blast furnaces (U.S.
EPA, 1992c). Research is also needed to
improve process control and modify existing
equipment. Examples include modifying a
blast furnace to reduce coke requirements and
adding coal tar decanter sludge to the coking
oven to reduce tar residue waste.
Solvents for Printing Processes
Toluene, MIBK, PERC, and TCA are used extensively during printing processes,
causing their high releases to the environment. The chemicals are used as
solvents in inks and adhesives, and as cleanup solvents. The wastes generated
during plate processing, printing, and binding generally include solvents from heat-
set inks, waste inks and ink sludges with solvents, cleanup solvents (including
halogenated and nonhalogenated), and solvents from adhesive use.
Use substitutions for solvent-based inks
and adhesives. It is possible to develop new
nonsolvent-based inks and adhesives. For
example, water-based inks have been devel-
oped for flexographic and rotogravure printing
processes. Water-based (Randall et al.,
1991), nonhalogenated, and high solids adhe-
sives have been developed or the ideas have
been suggested.
Use nonhazardous cleaning solutions. It
may be possible to use/develop nonhazardous
cleaning solutions or non-solvent-based clean-
ers.
Research needs. Research is needed to
determine the performance requirements for
the nonsolvent-based inks and adhesives and
to identify test methods to measure the perfor-
mance with respect to those standards. The
candidate materials can be identified and
tested as substitutions for printing and binding.
Research needs. Research is needed to
identify and validate new non-solvent-based or
nonhazardous cleaning solutions. The perfor-
mance requirements and test methods need to
97
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ELEVEN TRI CHEMICALS
Use source reduction and recycling. A
variety of source reduction and recycling
methods may be applicable to reduce or
eliminate the releases of the toxic solvents.
Solvents for Rubber and Miscellaneous
Plastic Manufacturing
be defined and identified. New cleaning
solutions will then be identified and tested.
Research needs. Research is needed to
identify the source of the waste and adequate
techniques that may achieve source reduction
and recycling objectives.
Organic solvents are used during compounding, fabricating, and converting of the
rubber and miscellaneous plastic products, and reclaiming of the waste materials.
Rubber compounding involves mixing, calendaring, and vulcanizing; plastics
compounding includes dry mixing of powders in a melt to produce pelletized or
diced resin. Fabricating operations usually involve shaping and transforming
rubber or plastic resin into a finished or semifinished product by molding, extrusion,
or other fabricating methods. Converting operations involve removing the rubber
or plastic overflow from the product before shipping. And reclaiming treats rubber
wastes with heat and chemical agents and transforms the material to its original
plastic state. These operations often produce spent solvents and fugitive solvent
emissions.
Avoid use of toxic solvents. It may be
possible to use alternative solvents in the
production of rubber and plastic products.
Use source reduction and recycling. There
may be ways to limit the use of solvents and/or
eliminate or reduce solvent emissions.
Research needs. Research is needed to
identify and validated new solvents to be used
in the manufacturing of rubber and plastic
products.
Research needs. When solvents must be
used, source reduction and recycling tech-
niques may be used to limit their use and/or to
eliminate or reduce solvent emissions. Sys-
tematic studies are needed to identify methods
to reduce solvent usage, opportunities to
eliminate process steps, methods to reuse or
recycle spent solvents, and techniques to
recover fugitive vapors.
Chemical Manufacturing
All of the eleven TRI organic chemicals are used, in one form or the other, as
basic feedstocks, intermediates, solvents, extractants, diluents, etc., in chemical
manufacturing. The industry is typified by its diversity in the types of processes,
techniques, and equipment used for both chemical manufacturing and pollution
prevention. Because of the competitive nature of the business, the industry
98
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ELEVEN TRl CHEMICALS
usually uses its enormous in-house research and development resources and
capabilities to develop specific pollution prevention methods for the manufacturing
of a given product. However, the results of these efforts are usually not available
to the public.
Use generalized pollution prevention tech-
niques. There may be ways to minimize the
release of hazardous organic chemicals during
the chemical manufacturing processes. The
best approach is to develop an understanding
of whatever general pollution prevention tech-
niques may apply to commonly used unit
operations within the industry (U.S. EPA,
1992e).
Research needs. A considerable research
program is needed to systematically study
common unit operations and the pollution
prevention techniques that may apply. The
information obtained can be used to determine
whether common industry usage of these
techniques could result in more efficient pollu-
tion prevention.
REFERENCES FOR ELEVEN TRl
ORGANIC CHEMICAL GROUPS
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NJ.
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Chemical Profile: Carbon Tetrachloride. 1989. Chemical Marketing Reporter,
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Chemical Profile: Chloroform. 1989. Chemical Marketing Reporter, Schnell
Publishing Co., New York, NY, February 27.
Chemical Profile: Methylene Chloride. 1989. Chemical Marketing Reporter,
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Chemical Profile: Trichloroethylene. 1989. Chemical Marketing Reporter, Schnell
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Chemical Profile: 1,1,1-Trichloroethane. 1989. Chemical Marketing Reporter,
Schnell Publishing Co., New York, NY, January 30.
Chemical Profile: Benzene. 1990. Chemical Marketing Reporter, Schnell
Publishing Co., New York, NY, April 23.
Chemical Profile: Methyl Isobutyl Ketone. 1990. Chemical Marketing Reporter,
Schnell Publishing Co., New York, NY, August 20.
99
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ELEVEN TRI CHEMICALS
Chemical Profile: Methyl Ethyl Ketone. 1990. Chemical Marketing Reporter,
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Cheney, JM and P. Kopf. 1990. "Paint Removal and Protective Coating
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Cundiff, C. H., O. L. Deel, and R. E. O'Sullivan. 1989. "Plastic Media Evaluation-
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FL
Galliher, R. D. 1989. "Surface Preparation and Paint Adhesion on Aluminum
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Hickman, J. C., and H. R. Goltz. 1991. "Temporary Vapor Storage Technology,"
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Ivey, R. B. 1990. "Carbon Dioxide Pellet Blasting Paint Removal for Potential
Application of Warner Robins Managed Air Force Aircraft," First Annual Internation-
al Workshop on Solvent Substitution, DE-AC07-76ID01570, U.S. Department of
Energy and U.S. Air Force, Phoenix, AZ, pp. 91-93.
Kirk, R., and D. Othmer (Eds.). 1978. Encyclopedia of Chemical Technology, 3rd
ed., Vol. 3, John Wiley & Sons, New York, NY.
Kirk, R. and D. Othmer (Eds.). 1983. Encyclopedia of Chemical Technology, 3rd
ed., Vol. 23, John Wiley & Sons, New York, NY.
Kirk, R. and D. Othmer (Eds.). 1984. Encyclopedia of Chemical Technology, 3rd
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Larson, N. 1990. "Low Toxicity Paint Stripping of Aluminum and Composite
Substrates," First Annual International Workshop on Solvent Substitution, DE-
AC07-76ID01570, U.S. Department of Energy and U.S. Air Force, Phoenix, AZ, pp.
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Lawler, G. M., Ed.. 1977. Chemical Origins and Markets, 5th ed., Chemical
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Lietzke, R. 1992. "Corrosion Busting Research Goal: Pre-Painting Automotive
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100
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ELEVEN TR1 CHEMICALS
Randall, P. M., G. Miller, W. J. Tancig, and M. Plewa. 1991. "Toxic Substance
Reduction for Narrow-Web Flexographic Printers," Proc. 7th Annual RREL
Hazardous Waste Research Symposium: Remedial Action, Treatment, and
Disposal of Hazardous Waste, EPA/600/9-91/002, U.S. Environmental Protection
Agency, Office of Research and Development, Washington, DC.
Reilly, W. 1990. "EPA's Goals for Reducing Releases of High Priority Toxic
Chemicals," presented to the National Press Club, September 26.
Sax, N.I-., and R.J. Lewis, Sr. (Eds.). 1987. Hawley's Condensed Chemical
Dictionary, 11th ed., Van Nostrand Reinhoid Co., New York, NY.
1988 Toxics Release Inventory (TRI) Releases/Transfers Database. 1988. ILS.
Environmental Protection Agency, Washington DC.
Ulrich, H., 1988. Raw Materials for Industrial Polymers, Oxford University Press,
New York, NY.
U.S. EPA. 1992a. Pollution Prevention Options in Metal Fabricated Products
Industries: a Bibliographic Report, EPA 560/8-92/002, U.S. Environmental
Protection Agency, Office of Toxic Substances, Washington, DC.
U.S. EPA. 1992b. Pollution Prevention Options in Petroleum Refining: a
Bibliographic Report, SAIC Draft Report to U.S. Environmental Protection Agency,
Office of Toxic Substances, Washington, DC.
U.S. EPA. 1992c. Pollution Prevention Options in Primary Metal Industries: A
Bibliographic Report, SAIC Draft Report to U.S. Environmental Protection Agency,
Office of Toxic Substances, Washington, DC.
U.S. EPA. 1992d. Pollution Prevention Options in Printing, Publishing and Allied
Industries: a Bibliographic Report, SAIC Draft Report to U.S. Environmental
Protection Agency, Office of Toxic Substances, Washington, DC.
U.S. EPA. 1992e. Possible Areas for Pollution Prevention Research, SAIC Draft
Report to U.S. Environmental Protection Agency, Office of Toxic Substances,
Washington, DC.
Wolf, K.,, A. Yazdani, and P. Yates. 1991. "Chlorinated Solvents: Will the
Alternatives be Safer?" J. Air Waste Manage. Assoc., 41(8): 1055. ;
*U.S.COVHlNMENTPWNnNCOFFJCE:1992 -648 -003£0058
101
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