GCA-TR-75-32-GI13)
ASSESSMENT OF ADIPIC ACID
AS A POTENTIAL AIR POLLUTION PROBLEM
VOLUME XIII
FINAL REPORT
Contract No. 68-02-1337
Task Order No. 8
Prepared For
U.S. ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park
North Carolina 27711
January 1976
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ASSESSMENT OF ADI?1C ACID
AS A POTENTIAL AIR POLLUTION PROBLEM
Volume XIII
by
Robert M° Patterson
Mark I. Bornstein
Eric Garshick
GCA CORPORATION
GCA/TECHNOLOGY DIVISION
Bedford, Massachusetts
January 1976
Contract No. 68-02-1337
Task Order No. 8
EPA Project Officer
Michael Jones
EPA Task Officer
Justice Manning
U.S. ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park
North Carolina 27711
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This report was furnished to the U.S. Environmental Protection Agency by the
GCA Corporation, GCA/Technology Division, Bedford, Massachusetts 01730, in
fulfillment of Contract No. 68-02-1337, Task Order No. 8. The opinions,
findings, and conclusions expressed are those of the authors and not neces-
sarily those of the U.S. Environmental Protection Agency or of the cooperating
agencies. Mention of company or product names is not to be considered as an
endorsement by the U.S. Environmental Protection Agency.
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ABSTRACT
This report is one of a series which assesses the potential air pollution
impacts of 14 industrial chemicals outside the work environment. Topics
covered in each assessment include physical and chemical properties,
health and welfare effects, ambient concentrations and measurement meth-
ods, emission sources, and emission controls. The chemicals investigated
in this report series are:
Volume I
Volume II
Volume III
Volume IV
Volume V
Volume VI
Volume VII
Volume VIII
Volume IX
Volume X
Volume XI
Volume XII
Volume XIII
Volume XIV
Acetylene
Methyl Alcohol
Ethylene Bichloride
Benzene
Acetone
Acrylonitrile
Cyclohexanone
Formaldehyde
Methyl Methacrylate
Ortho-Xylene
Maleic Anhydride
Dimethyl Terephthalata
Adipic Acid
Phthalic Anhydride.
lit
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CONTENTS
Page
Abstract iii
List of Tables v
Sections
I Summary and Conclusions 1
II Air Pollution Assessment Report 3
Physical and Chemical Properties 3
Health and Welfare Effects 4
Ambient Concentrations and Measurements 5
Sources of Adipic Acid Emissions 8
Adipic Acid Control Methods 10
III References 12
Appendix
A Adipic Acid Manufacturers 2_4
iv
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TABLES
No. Pagg
1 Significant Properties of Adipic Acid 3
2 Estimated Adipic Acid Consumption 8
3 Sources and Emission Estimates of Adipic Acid 9
4 Scrubber 11
5 Cyclones 11
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SECTION I
SUMMARY AND CONCLUSIONS
Adipic acid is an odorless, white crystalline powder which is manufactured
by the catalytic oxidation of cyclohexane, with cyclohexanone and cyclo-
hexanol as intermediates. Its primary use is in the production of poly-
amide fibers and plastics.
Adipic acid dust in air may irritate mucous membranes and may cause derm-
atitis. When ingested it is no more toxic than common food acids such
as citric acid, and it is used as a baking powder ingredient and as a
food additive. The main hazard in air is the possibility of dust ex-
o
plosions, and the lower explosive limit is 10 to 15 g/m .
Simple diffusion modeling estimates place the likely maximum 1-hour
3
average ambient concentration at about 0.67 mg/m (0.11 ppm), and
3
0.37 mg/m (0.062 ppm) for a 24-hour average. There is no NIOSH re-
commended occupational standard.
About 1.5 billion pounds of adipic acid were produced in 1974, and pro-
duction is expected to increase about 7 percent per year for the next
several years. The primary emission sources are production and end-
product manufacture. Total emissions are estimated to have been 1.5
million pounds in 1974.
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Emission control methods currently in use and their efficiencies are:
9 Scrubbers 90 percent
» Cyclones 93 ..8+ percent
« Bag filters Almost 100 percent
Based on the results of the health effects'research presented in this
report, and the ambient concentration estimates, adipic acid as an air
pollutant apparently does not pose a threat to the health of the gen-
eral population. In addition, adipic acid does not appear to pose
other environmental insults which would warrant further investigation
or restriction of its use at the present time.
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SECTION II
AIR POLLUTION ASSESSMENT REPORT
PHYSICAL AND CHEMICAL PROPERTIES
Adipic acid is an odorless, white crystalline powder. It is manufactured
by the catalytic oxidation of cyclohexane with cyclohexanone and cyclo-
hexanol as intermediates. Some adipic acid is used as a baking powder
ingredient and as a food additive. Its main outlet is as a raw material
for the production of polyamide fibers and plastics (nylon 6,6), and for
resins used in electrical insulation and protective coatings. Signifi-
cant physical properties are presented in Table 1.
Table !„ SIGNIFICANT PROPERTIES OF ADIPIC ACID
Synonyms
Hexanedioic acid, 1, 4-butanedicarboxylic acid
Chemical formula
Molecular weight
Boiling point
Melting point
Specific gravity
Vapor pressure
Solubility
Lower explosive limit
Ignition temperature
Flash point
At 25°C and 760 mm Hg
COOH(CH2)4COOH
146.14
At 760 mm Hg 330 C with decomposition
100 mm Hg 265°C
152°C
1.360 (25°/4°C)
<1 mm Hg at 25°C
1 mm Hg at 159.5°C
2.5 percent by weight at 25 C in water
Soluble in alcohol
3
10 to 15 g/m dust in air
550°C (200 mesh particles)
191 C (closed cup)
1 ppm = 6 mg/m
1 mg/m^ - 0.167 ppm
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HEALTH AND WELFARE EFFECTS
Effects on Man
Adipic acid dust in air may act as an irritant on the mucous membranes
of the lungs and nose. It has a drying action on the skin and may cause
dermatitis. There have been no reports in the literature of injury
during industrial usage. Exposure to adipic acid vapor is impossible at
ambient conditions due to its low vapor pressure.
Adipic acid once ingested is no more toxic than common food acids such
as citric acid. Humans were fed 100 mg/kg body weight for up to 8 days
2
with no toxic effects. No occupational exposure standard has been
3
established, but its lower explosive limit of 10 to 15 g/m of air must
be noted.
Effects on Animals
Acute Poisoning - Adipic acid in animals, as in man, may act as a mucous
membrane irritant. In rats, death has been caused by oral administration
2
of 3,600 mg/kg body weight. In mice the oral LD.-Q is 1,900 mg/kg,
Chronic Poisoning - Two male and two female rats were exposed to 126
3 4
mg/m adipic acid dust for 6 hours daily for 15 days. There were
no toxic signs and all blood tests were normal. The animals were sacri-
ficed, with an autopsy showing no changes in any organ. Female albino
rats fed 1.0 percent adipic acid in their daily diet for 2 years showed
no evidence of toxicity related to the compound. Male albino rats fed
adipic acid at the 0.1, 1.0, 3.0, and 5.0 percent levels in the daily
diet showed no ill effects, except at the 3.0 and 5.0 percent level a
temporary retardation of growth was observed.
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Effects on Vegetation
The effects of adipic acid on vegetation have not been documented in
the literature.
Effects on Materials
Violent chemical reactions may occur when adipic acid comes in con-
tact with strong oxidizing agents.
Other Effects
Decomposition - Heating above 330 C or prolonged heating at its melting
point causes decomposition to cyclopentanone, n-valeric acid, and other
compounds that are toxic,to man and animals.
Explosive Dust - The principal hazard associated with adipic acid in
air is the danger of dust explosions ' ' as with any organic powder.
AMBIENT CONCENTRATIONS AMD MEASUREMENTS
Ambient Concentration Estimates
The largest installation for adipic acid production is located in a
town of about 60,000 population, and it has a capacity of about 620
million Ib/yr. Assuming a 0.05 percent loss, this converts to an
emission rate of:
(0.0005 emission factor) (620 x 1Q6 Ib/yr) (453,6 g/lb)
3.1536 x 107 sec/yr
= 4.5 g/sec of adipic acid.
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Some assumptions must be made regarding this adipic acid release to
the atmosphere. First of all, the emissions do not all come from one
source location, but rather from a number of locations within the plant.
Thus, the emissions can be characterized as coming from an area source
which will be taken to be 100 meters on a side. Secondly, the emissions
occur at different heights, and an average emission height of 10 meters
is assumed. Thirdly, it is assumed that these emissions are in the form
of particulate small enough to behave as a gas (of the order of 10
Ground level concentrations can then be estimated at locations downwind
o
of the facility. To do this a virtual point source of emission is
assumed upwind of the facility at a distance where the initial horizontal
dispersion coefficient equals the length of a side of the area divided by
4.3. In this case:
a = 100m/4.3 = 23.3m
yo
Assuming neutral stability conditions (Pasquill-Gifford Stability Class D)
with overcast skies and light winds, the upwind distance of the virtual
point source is approximately 310 meters. With consideration of the plant
boundary, it is reasonable to assume that the nearest receptor location is
thus about 500 meters from the virtual point source. Finally, taking
2 m/sec as an average windspeed, the ground level concentration may be
calculated from:
x =
or
10
\2
r
(2) it (36) (18.5) \18.5/
3
=0.93 mg/m
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for a 10-minute average concentration. Over a period of an hour this
o o
becomes 0.93 mg/m (0.72) = 0.67 mg/m 1-hour average concentration.
Over a 24-hour period, the average concentration might roughly be
expected to be about 0.37 mg/m3.
Me a s ur erne n t Te chniques
Very limited data exist in the literature for the determination of
adipic acid in air. Considerable attention has been given to the
elution of free monobasic carboxylic acids. However; very limited
work with dibasic acids has been performed. Because of the difficul-
ties associated with the elution of these normally solid, high boil-
ing point compounds, previous gas chromatograph analyses have been
indirect., These methods have relied on preinjection treatments of the
dibasic acid, consisting of either reduction to a glycol and/or esteri-
fication. The accuracy of these methods is very questionable, and they
9
are time consumingo
Studies have been performed on a more reliable method for the deter-
mination of adipic acid. In one technique adipic acid is determined
by using a GC and a flame ionization detector xvithout any preinjection
treatment. Adipic acid dissolved in dimethyl formamide is introduced
into the GC column. The column is composed of 316 stainless steel
(2 feet by 1/8 inch) packed with Porapak Q coated with 7 weight percent
FFAP, terephthalic acid terminated carbowax 20 M, commonly referred to
as "Free Fatty Acid Phase." This experiment was unfortunately only run
on samples containing 5.9 to 25.0 weight percent adipic acid; however,
excellent results were obtained. The sensitivity of this method implies
that adipic acid can be determined in the parts per billion range.
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SOURCES OF ADIPIC ACID EMISSIONS
Adjjjjc_ AcidJProduction. and Consumption
The production of adipic acid in 1974 was 1,505 million pounds, and it
is expected to increase at 6.9 percent per year for the next several
12
years. Approximately 90 percent of all adipic acid produced is used
for the manufacture of nylon 6,6. Plasticizers, lubricants, and poly-
urethane resins consume an additional 8 percent of the total production.
Five companies at 7 locations are presently manufacturing adipic acid.
See Appendix A for names and locations. The consumption of adipic acid
13
for final products is shown in Table 2. Expected growth rates for each
sector of the market are also shown in this table.
Table 2. ESTIMATED ADIPIC ACID CONSUMPTION - 1974
13
Nylon fibers
Nylon resins
Plasticizers and lubricants
Polyurethane resins
Polyester resins
Food additives
Miscellaneous
Million pounds
1301
69
•61
58
6
8
2
1505
% annual
growth
7.3
7.3
1.8
1.8
1.8
1.8
0
6.9
Adipic Acid Sources and Emission Estimates
Primary sources of emissions of adipic acid result from adipic acid
production and end product manufacture. Total emissions from both
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categories are estimated to be 1.5 million pounds representing 0.1
percent of total production as shown in Table 3.
Table 3.
SOURCES AND EMISSION ESTIMATES
OF ADIPIC ACID
Million pounds
Adipic acid production
End product manufacture
Total
0.75
0.75
1.50
Adipic acid is manufactured by reacting cyclohexanone/cyclohexanol
with nitric acid. The following two equations illustrate the re-
actions involved.
0
II
/c>
Ho C C HO
I I
H2 C C H2
'c'
Ho
Cyclohexanone + Citric Acid
H2C - CH - COOH H_
H2C - CH2 - COOH
NO
Adipic Acid + Nitrogen Oxide + Vater
H OH
r
HJNUj
H2 c c n^
Ho C C Ho
c'
H2
Cyclohexanol+Kitric Acid
- CH2 - COOH
- CH2 - COOH
NO
1CO
1C.
Adipic Acid
+ Nitrogen Oxide + Water
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In a recent study on adipic acid manufacture it \-jas reported that
the only source of adipic acid emissions results from conveyors,
driers, and melters. The emission factor reported was 0.0005 pounds
of adipic acid lost per pound of adipic acid produced. Using this
factor and the most recent production figure results in 0.75 million
pounds of adipic acid emitted to the atmosphere from production.
Emissions from end product manufacture are similarly estimated to be
0.75 million pounds <> Only trace quantities have been reported from
the manufacturing of nylon 6,6, the major use of adipic acid.
Storage losses are considered to be negligible because the final pro-
duct is a solid and is not subject to evaporation. Any handling losses
resulting from the storage of the final product are already included in
the previously mentioned emission factor.
ADIPIC ACID CONTROL METHODS
Three types of control devices are currently being used by the industry
to reduce emissions: scrubbers, cyclones and bag filters. In a recent
study concerning the adipic acid industry} one plant is reportedly using
a scrubber with an efficiency of approximately 90 percent. This system
is used to control adipic acid dust generated from finished product
operations. Two other plants using cyclones with efficiencies between
93.8 percent and 100 percent, and bag filters with efficiencies approach-
ing 100 percent, have also been reported. Cost data for the various
systems are presented in Tables 4 and 5. Complete data for the bag
filter system, however, are not available. The only information which is
available is the installed cost of $48,000.
'Updated to first quarter 1975.
10
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Table 4. SCRUBBER
a
Scrubbing liquid rate
Design temperature
Gas rate
Installed cost
Annual operating cost
Value of recovered product
Net operating cost
Efficiency
5 GPM
120°F
18,000 SCFM
$46,100
$ 4,600
0
$ 4,600
907.
'Costs updated to first quarter 1975.
Table 5. CYCLONES3
Installed cost
Annual operating cost
Value of recovered product
Net operating cost
Efficiency
$51,200
$ 2,600
$ 4,345
-$ 1,745
93.8%
JCosts updated to first quarter 1975.
11
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SECTION III
REFERENCES
IP Adipic Acid. National Safety Council Data Sheet. National Safety
Council, 425 North Michigan Avenue, Chicago. 1956.
2. Weizel, G. Zeitschrifte Physiologische Chemie. (Germany).
282:185-91. 1947.
3. The NIOSH Toxic Substances List 1974 Edition. HEW Publication No.
(NIOSH) 74-134.
4. Gage, J« C. The Subacute Inhalation Toxicity of 109 Industrial
Chemicals. Brit. J. Ind. Med. 27:1-18. 1970,
5o Hazelton Laboratory Reports dated August 20, 1952 and December 31,
1952 (unpublished data). Cited in Reference 1.
6. OSHA Material Safety Sheet. E. I. DuPont de Nemours & Company, Inc.,
1007 Market Street, Wilmington. 1972.
7o OSHA Material Safety Sheet. Monsanto Company, 800 North Lindbergh
Boulevard, St. Louis. 1972.
8. Turner, D. B. Workbook of Atmospheric Dispersion Estimates. U.S.
Environmental Protection Agency, Report No. AP-26. April 1973.
9. Appleby, A., J. Mayre. Journal of Gas Chromatography, Vol. 5.
1967.
10. Gross, D., H. Tinker. Quantitative Gas Chromatographic Determina-
tion of Free Adipic Acid. Analytical Chemistry. January 1968.
11. Leithe, W. The Analysis of Air Pollutants. Ann Arbor-Humphrey
Science Publishers. 1970.
12. U.S. Production of Selected Snythetic Organic Chemicals. United
States International Trade Commission Preliminary Report. May 16,
1975.
12
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13o Chemical Economics Handbook. Stanford Research Institute.
January 1974.
14. Survey Reports on Atmospheric Emissions from, the Petrochemical
Industry, Volume !„ UoSo Environmental Protection Agency, Report
No. EPA-450/3-73-005a. January 1974.
15o Survey Reports on Atmospheric Emissions from the Petrochemical
Industry, Volume II. U°So Environmental Protection Agency, Report
No. EPA-450/3-73-005-C<, April 1974.
16. Chemical Profile, Adipic Acid, April 28, 1975.
13
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APPENDIX A
ADIPIC ACID MANUFACTURERS16
Annual capacity,
million pounds
Allied Chemical Corporation Hopewell, Virginia 25
Celanese Corporation Bay City, Texas 140
DuPont Orange, Texas 300
DuPont Victoria, Texas 350
El Paso Natural Gas Company Odessa, Texas 80
Monsanto Luling, Louisiana 60
Monsanto Pensacola, Florida 620
Total 1575
*As of April 1975.
14
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