GCA-TR-75-32-G (12)
ASSESSMENT OF DIMETHYL TEREPHTHALATE
AS A POTENTIAL AIR POLLUTION PROBLEM
VOLUME XII
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
GCA TECHNOLOGY DIVISION
BEDFORD, MASSACHUSETTS 01730
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GCA-TR-75-32-0(12)
ASSESSMENT OF DIMETHYL TEREI'imiALATG
AS A POTENTIAL AIR POLLUTION PROBLEM
Volume XII
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 Dichloride
Benzene
Acetone
Acrylonitrile
Cyclohexanone
Formaldehyde
Methyl Methacrylate
Ortho-Xylene
Maleic Anhydride
Dimethyl Terephthalate
Adipic Acid
Phthalic Anhydride.
iii
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CONTENTS
Page
Abstract
List of Tables
v
Sections
I Summary and Conclusions i
II Air Pollution Assessment Report 3
Physical and Chemical Properties 3
Health and Welfare Effects 4
Ambient Concentrations and Measurements 5
Sources of Dimethyl Terephthalate Emissions 7
Dimethyl Terephthalate Emission Control Methods 10
III References
Appendix
A Manufacturers of Dimethyl Terephthalate 13
iv
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TABLES
No.
Page
1 Significant Properties of Dimethyl Terephthalate 3
2 Dimethyl Terephthalate Consumption - 1974 8
3 Sources and Emission Estimates of Dimethyl
Terephthalate — 1974 o
4 Absorber/Scrubber for Control of Hydrocarbon Emissions 11
5 Bag Filters for Control of Terephthalic Acid H
6 Incinerator with Waste Heat Boiler
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SECTION I
SUMMARY AND CONCLUSIONS
Dimethyl terephthalate is a white crystalline solid. It is manufactured
by the oxidation of para-xylene to terephthalic acid, with subsequent
methanol esterification. Dimethyl terephthalate is used almost exclu-
sively in the production of polyester fibers and polyester films.
Data on human health effects from dimethyl terephthalate are lacking,
and there is no standard for occupational exposures. Contact with dust
may be slightly toxic only at high doses. No effects or. vegetation have
been documented.
Simple conservative diffusion modeling estimates place the likely maxi-
3
mum 1-hour average ambient concentration at 8.34 mg/m (1.05 ppm). The
maximum 24-hour average ambient concentration might be expected to be
3
about 4.63 mg/m (0.58 ppm). Dimethyl terephthalate is usually found
in air as a dust.
Almost 3 billion pounds of dimethyl terephthalate v?ere produced at seven
locations in 1974, and production is expected to increase at over 8 per-
cent per year through 1979. The primary emission sources are production
and end-product manufacture. Total emissions are estimated to have been
about 18 million pounds in 1974.
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Emission control methods and reported efficiencies are:
• Scrubbers 93.8 to 99.4 percent
• Bag filters Almost 100 percent
• Incinerators 99 percent
Based on the results of the health effects research presented in this
report, and the ambient concentration estimates, dimethyl terephthalate
as an air pollutant apparently does not pose a threat to the health of
the general population. In addition, dimethyl terephthalate 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
Dimethyl terephthalate (DMT) is a white crystalline solid. It is manu-
factured by the oxidation of para-xylene to terephthalic acid, with
methanol esterification to DMT. DMT is a key chemical intermediate in
the manufacture of polyester fibers and films. Derivatives are found
in coating compositions, insulation, paint and varnish, magnet wire,
plasticizers, antifoam agents, and specialty lubricants. Significant
properties are given in Table 1.
Table 1. SIGNIFICANT PROPERTIES OF
DIMETHYL TEREPHTHALATE
Synonym
DMT
Chemical formula
Molecular weight
Boiling point
Melting point
Specific gravity
Vapor pressure
Solubility
Flash point
At 25°C and 760 imn Hg
C-OCH,
CH-jO-C
194.18
285°C
140. 6°
1.04
10 mm Hg at 142 C
100 nmi Hg at 208°C
0.3 g/100 ml hot water
151°C (closed ci:p)
146 C (opon cup)
1 ppm = 7.937 mg/m
1 mg/n|3 0.126 ppm
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HEALTH AND WELFARE EFFECTS
Effects on Man
The effects of DMT on. man have not been well documented in the litera-
ture. Its low vapor pressure would tend to prevent any appreciable
2 3
intake by vapor inhalation. ' Eye or skin contact with the dust may
cause slight, transient irritation. Based on studies done on animals,
x
oral ingestion would be slightly toxic only at high levels. No adverse
health effects were seen in workers in a factory with air contaminated
4
with DMT. A standard for occupational exposure has not been established;
however, care must be taken to avoid prolonged or excessive contact
because of its irritating properties.
Effects on Animals
Acute Poisoning - DMT dust at high levels, 86.4 mg/m (10.9 ppm), can
2
act as a mild nasal and eye irritant. Oral doses as high as 6590 mg/kg
given to rats caused no deaths. The intraperitoneal LD n was 3900 mg/kg,
with all deaths occurring within 48 hours after injection. Slight-to-
moderate weakness was seen At all dose levels regardless of the method
of administration. At the two highest oral dose levels, 5020 and
6590 mg/kg, there were slight tremors and some ataxia. Autopsies revealed
no gross microscopic abnormalities in the organ systems of the animals.
A quantity of 0.5 mi of a 1 percent DMT solution dropped on the rump area
of guinea pigs caused no primary irritation. It was found not to be a
skin sensitizer. Moistened DMT in contact with the depilated skin of
guinea pigs caused only slight skin irritation with no evidence of direct
absorption through intact skin. One drop of a water slurry placed in
the conjunctival sac of a rabbit's eye resulted in only slight, immediate
discomfort, with no permanent injury resulting.
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3
Chronic Poisoning - Rats exposed to 86.4 mg/m (10.9 ppm) DMT dust for
4 hours per day for 58 exposures started nose rubbing, preening and
blinking soon after the start of exposure. The symptoms continued inter-
mittently throughout the exposure period and were seen in the successive
exposures. Exposure to 16.5 mg/m (2.1 ppm) for the same duration and
frequency produced no toxic effects or abnormal behavior. Microscopic
examination of all organ systems showed no evidence of any abnormalities.
Feeding rats at a 5 percent level in the daily diet (3.75 g/kg daily)
for 28 days resulted in a loss of weight, a marked reduction of food
consumption, and high mortality. Rats fed at a 1 percent level in their
daily diet for 96 days showed a significant reduction in average body
3
weight as compared to controls. The mechanism of the effects of DMT
on rats is unknown.
Effects on Vegetation.
The effect of DMT on vegetation has not been documented in the literature,
Other Effects
When DMT is heated, it will sublime and can form a potentially explosive
6
dust. The flash point is 146°C by the open cup method. Contact with
strong oxidizing agents will cause a chemical reaction.
AMBIENT CONCENTRATIONS AND MEASUREMENTS
Ambient Concentration Estimates
The largest installation for dimethyl terephthalate production is located
near a town of about 50,000 population, and it has a capacity of about
1,300 million Ib/yr. Assuming a 0.3 percent loss, this converts to an
emission rate of:
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(0.003 emission factor) (1300 x 1Q6 Ih/yr) (453.6 p./lb)
3.1536 x 107 sec/yr
=56.1 g/sec of dimethyl terephthalate.
Some assumptions must be made regarding this dimethyl terephthalate re-
lease to the atmosphere. First of all, the emissions do not all come
from one source location, but rather from a number of locations x^ithin
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 um).
Ground level concentrations can then be estimated at locations downwind
of the facility. To do this a virtual point source of emission is
assumed upwind of the facility at a distance where the initial hori-
zontal dispersion coefficient equals the length of a side of the area
divided by 4.3. In this case:
or = 100 m/4.3 = 23.3 m .
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 wind speed, the ground level concentration may be
calculated from:
X= *— exp
U7T<7 <7 r
y z
-1/2 *r-
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or
X =
56.1
-1/2
(2)7r(36)(18.5)
= 11.58 mg/m
for a 10-minute average concentration. Over a period of an hour this
3 3
becomes 11.58 mg/m (0.72) = 8.34 mg/m (1.05 ppm) 1-hour average concen-
tration. Over a 24-hour period, the average concentration might roughly
3
be expected to be about 4.63 mg/m (0.58 ppm).
Dimethyl Terephthalate Measurement Techniques
Dimethyl terephthalate present as an airborne particulate should be col-
lected on a Whatman No. 1 filter paper or on a glass filter. For the
collection of vapor or fumes, two gas washing bottles or bubblers in
Q
series containing spectrographic grade 3-A alcohol are used.
One method, which has a high degree of sensitivity for measuring dimethyl
terephthalate, is collecting the sample using bubblers or filter paper,
with the subsequent extraction of the particles from the filter paper
with a suitable solvent. The absorbence of the sample is measured in an
ultraviolet spectrophotometer at 225 m|a and then compared to a standard
calibration curve. Interferences will result from other aromatic sub-
stances present in the sample. A 1-cubic foot air sample will allow
detection to 0.02 ppm.
SOURCES OF DIMETHYL TEREPHTHALATE EMISSIONS
Dimethyl Terephthalate Production and Consumption
The production of dimethyl terephthalate (DMT) is estimated to have been
2,953 million pounds in 1974, and it is expected to increase at 8.2 percent
7
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per year through 1979. Dimethyl terephthalate is used almost exclusively
to produce polyester fibers and polyester films. In 1973 about 73 percent
of all polyester fibers produced in the United States were based on DMT.
The production of polyester films for magnetic tapes, photographic films
and packaging applications accounted for almost the remainder of the
total production. Five companies at seven locations are presently pro-
ducing dimethyl terephthalate. See Appendix A for names and locations.
The consumption of dimethyl terephthalate for final products is shown in
Table 2. This table also shows the expected growth rate for each sector
of the market.
Table 2. DIMETHYL TEREPHTHALATE CONSUMPTION - 1974'
Product
Polyester fiber
Polyester film
Polybutylene terephthalate
resins
Miscellaneous
Total
Millions
of pounds
2726
207
15
5
2953
Annual
% growth
8.0
9.0
38.0
5.0
8.2
Dimethyl Torephthalate Sources and Emission Estimates
Primary sources of emissions of dimethyl terephthalate occur from pro-
duction, end-product manufacture, and storage. Total emissions of
dimethyl terephthalate are estimated to have been 17.83 million pounds
in 1974, representing 0.6 percent of total production. See Table 3.
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Table 3. SOURCES AND EMISSION ESTIMATES OF
DIMETHYL TEREPHT1IALATE - 1974
Source
Dimethyl terephthalate
production losses
End-product losses
Storage
Total
Emissions,
million pounds/year
8.9
17.83
The major sources of emissions of dimethyl terephthalate occur from pro-
duction and end-product losses. Three processes are currently being used
to manufacture DMT: Dupont Process, Tennessee Eastman Process, and the
Hercules Process. The Dupont Process, which is generally considered
obsolete, begins with para-xylene, which is oxidized with nitric acid
to para-toluic acid. It is further treated under pressure and converted
to terephthalic acid, which is then esterified to DMT. This process is
still being used by Dupont at one of their production sites.
The Tennessee Eastman Process is also based on para-xylene feedstock and
a crude terephthalic acid intermediate. Para-xylene is oxidized at a
low temperature and pressure with acetic acid solvent, a cobalt acetate
catalyst, and an acetaldehyde activator. The crude terephthalic acid
is then esterified with methanol to produce DMT.
The Hercules Process, which accounts for the bulk of DMT production,
is based on Witten-Imhausen technology. Para-xylene is oxidized with
air under mild operating conditions to produce toluic acid, which is
esterified to its methyl ester. The methyl toluate is oxidized under
more severe conditions to moiiomethyl terephthalate which is then esteri-
fied to form DMT.
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Emissions data for these processes are not readily available in the
literature; however, data for the production of terephthalic acid (TPA)
do exist, and because of the similarity between the processes, these
will be used in estimating production losses of DMT.
In a recent report concerning emissions from the production of. TPA, it
was estimated that approximately 0.3 percent of production is lost in
the form of TPA. Using this report as a basis, it is estimated that
production losses from DMT production will also be 0.3 percent. Using
2953 million pounds as the most recent production figure, losses are
estimated to be 8.9 million pounds.
Since emission data from the use of DMT are not readily known, it is
assumed that end-product losses are also 8.9 million pounds.
Emissions from product storage and handling are estimated to be 10
pounds of DMT emitted per pound of DMT transported. This results in
0.03 million pounds of DMT powder lost from storage and handling.
DIMETHYL TEREPHTHALATE EMISSION CONTROL METHODS
Three types of control devices are currently being used by the chemical
industry: scrubbers, bag filters, and incinerators. A recent study
indicated .that these three control methods are used extensively in the
manufacture of terephthalic acid. It is assumed that these three methods
are also used in the production of dimethyl terephthalate.
The bag filter is reported to have an efficiency approaching 100 percent.
The incinerator is reported to combust organic acids and methanol with
an efficiency of 99 percent and the scrubber has a reported efficiency
of from 93.8 to 99.4 percent. Cost data for the various systems are
presented in Tables 4, 5, and 6.
10
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Table 4. ABSORBER/SCRUBBER3 FOR CONTROL OF
HYDROCARBON EMISSIONS10
Design temperature
Gas rate
Installed cost — material and labor
Annual operating cost
Value of recovered product
Net operating cost — annual profit
Efficiency
120°F
32,150 scfm
$147,000
$117,800
$479,800
$362,000
93.8-99.4%
Costs updated to first quarter 1975.
Table 5. BAG FILTERS FOR CONTROL OF
TEREPHTHALIC
Design temperature
Installed cost — material and labor
Annual operating cost
Efficiency
275°F
$39,750
$ 6,450
* 100%
Costs updated to first quarter 1975.
Table 6.
INCINERATOR3 WITH WASTE HEAT BOILER10
Type of compounds incinerated
Quantity incinerated
Auxiliary fuel
Rate
Stack height
Installed cost — material and labor
Annual operating cost
Value of heat/steam recovered
Net annual operating cost
Efficiency
Organic- acids
and methanol
40 gpra
Fuel oil
126 gph
100 feet
$987,200
$214,550
$106,600
$107,950
99%
Costs updated to first quarter 1975.
11
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SECTION III
REFERENCES
1. Dimethyl Terephthalate DMT. Eastman Technical Data Sheet No. X-135.
Eastman Chemical Products, Inc., Kingsport, Tennessee. Subsidiary
of Eastman Kodak Company.
2. Krauskupf, L.D. Studies on the Toxicity of Phthalates via Ingestion.
Environ Health Perspec Exper. 3:61-62, 1973.
3. Krasavage, W.J., F.J. Yanna, and C.J. Terhaar. Dimethyl Terephthalate
(DMT): Acute Toxicity, Subacute Feeding and Inhalation Studies in
Male Rats. Am Ind Hyg Assoc J. 34:455-62, 1973.
4. Dol'nik, R.I., and L.M. Polubova. Hygienic Evaluation of Working
Conditions During the Sewing of Objects Hade From Lavsan-Containing
Fabrics. Gig Tr Prof Zabol. 15:35-7, 1971. Cited in Chem Abstracts
75:154745g, 1971.
5. Fassettj D.W. Esters. In: Industrial Hygiene and Toxicology, 2:1911.
Patty, F.A. (ed.). New York, Interscience Publishers, 1963.
6. OSHA Material Safety Sheet. Dimethyl Terephthalate. .E.I. duPont de
Nemours & Co., Wilmington, North Carolina.
7. Turner, D.B. Workbook of Atmospheric Dispersion Estimates. U.S.
Environmental Protection Agency, Publication Number AP-26. April 1973.
8. Industrial Hygiene and Toxicology. Second Edition, Volume II.
John Wiley and Sons. 1963.
9. Chemical Economics Handbook. Stanford Research Institute. May 1975.
10. Survey Reports on Atmospheric Emissions from the Petrochemical
Industry. Volume II. U.S. Environmental Protection Agency,
Report Number 450/3-73-005-b. April 1974.
12
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APPENDIX A
MANUFACTURERS OF DIMETHYL TEREPHTHALATE'
American Hoechst Corp.
Amoco Chemicals Corp.
Amoco Chemical Corp.
Dupont
Dupont
Eastman Kodak Co.
Hercules Incorporated
Spartanburg, S. Carolina
Decatur, Alabama
Joliet, Illinois
Wilmington, N. Carolina
Old Hickory, Tenn.
Kingsport, Tenn.
Wilmington, N. Carolina
Total
Annual capacity,
million pounds
160
200
150
750
300
400
1,300
3,260
13
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