United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-84-052 May 1984'
&ER& Project Summary
Buffer Additives for
Lime/Limestone Slurry
Scrubbing Synthesis, Mass
Transfer, and Degradation
Gary T. Rochelle, Raymond J. Smith, W.T. Weems, Mary W. Hsiang, and
Yungli Lee
Experimental studies were performed
with buffer additives useful for flue gas
desulfurization by lime/limestone
slurry scrubbing. The rates of reaction
of acrylic acid and maleic anhydride
with bisulfite at 55°C were sufficiently
fast to permit in situ synthesis in a
slurry scrubber of sulfopropionic and
sulfosuccinic acids, respectively, ft-
Hydroxypropionic acid was synthesized
by hydration of acrylic acid at 100 -
140°C with catalysis by H2SO< or cation
exchange resin. Enhancement of SOa
absorption by acetic, adipic, hydroxy-
propionic, sulfopropionic, and sulfo-
succinic acids and by basic aluminum
sulfate was measured at 55°C in 0.3 M
NaCI and 0.1 M CaCI2, and was
successfully modeled by mass transfer
with equilibrium reactions. Oxidation of
carboxylic acids conjugated with oxida-
tion of CaSOs slurry was studied for
seven acids. Oxidative degradation of
adipic acid and other aliphatic and
sulfocarboxylic acids was least at pH 4.3
with 1.0 mM dissolved Mn and greatest
at pH 5.5 without Mn. Hydroxyacetic
and hydroxypropionic acids inhibited
sulfite oxidation and were less subject
to degradation. The most attractive
acids for further testing are adipic,
mixtures of waste dibasic organic,
sulfosuccinic, hydroxypropionic, and
hydroxyacetic acids.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory. Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
Lime/limestone slurry scrubbing is the
dominant commercial technology for flue
gas desulfurization. S02 is absorbed at
50-55°C and pH 4.5-6.0 in an aqueous
slurry of excess limestone and product
solids. The calcium sulfite (CaSOaJ/cal-
cium sulfate (CaSCU) product is disposed
of as solid waste. With greater than 500-
1000 ppm SO2 in the flue gas, SO2
absorption is controlled by liquid/film
mass transfer resistance because of the
limited solubility of SO2 gas and alkaline
solids. Additives that buffer between pH 3
and 5.5 enhance SOi absorption by
providing dissolved alkaline species for
reaction with SOa. This is a report of
experimental investigations to provide
data for the evaluation of buffer additive
alternatives. This work was summarized
in 1982 and was also included in an
extensive review of buffer additives that
same year.
An attractive buffer additive should be
inexpensive, provide mass transfer
enhancement at low concentrations, and
be nonvolatile and chemically stable at
scrubber conditions. The important
classes of inexpensive nonvolatile buffers
include polycarboxylic acids (e.g., adipic),
hydroxycarboxylic acids (e.g., hydroxypro-
pionic), and sulfocarboxylic acids (e.g.,
sulfopropionic). Some of these alternatives
are not commercially available and must
be synthesized from inexpensive raw
-------
materials. The synthesis of hydroxypro-
pionic, sulfopropionic, and sulfosuccinic
acids has been demonstrated. This report
gives quantitative reaction kinetics for
the synthesis of these three alternatives.
This work was also published as a mas-
ter's thesis in 1981.
Mass transfer enhancement depends
on the buffering properties and diffusivity
of the additive. Effective pka values of
buffer alternatives at scrubber conditions
were measured in 1978. A model of
enhancement, based on mass transfer
with equilibrium reactions, was developed
in 1981, the^same year that its effective-
ness with acetic and adipic acids was
experimentally demonstrated at 25°C.
This report gives experimental and model
results at 55°C with several buffer
alternatives. Details of the work are also
given in a master's thesis in 1981.
Organic acids are normally stable to
oxidation, but laboratory and pilot plant
results have shown that adipic acid
oxidizes in conjugation with sulfite
oxidation in the scrubber. This report
gives oxidative degradation rates of adipic
acid as a function of pH and Mn concen-
tration. Results are also presented for
glutaric, succinic, sulfopropionic, sulfo-
succinic, fumaric, hydroxypropionic, and
hydroxyacetic acids. Details of the work
are given in master's theses in 1980 and
1981.
Buffer Synthesis
Sulfocarboxylic and hydroxy car boxy lie
acids are attractive as buffer additives
because the additional hydrophilic groups
make both the buffer and its degradation
products nonvolatile in aqueous solution.
Available kinetic data on sulfite addition
to maleic or acrylic acid to give sulfosuccinic
or /3-sulfopropionic acid were evaluated
in 1977. The feasibility of hydrating
acrylic acid with H2SO4 catalysis at 100°C
to get /J-hydroxypropionic acid was
demonstrated in 1978.
This report gives measurements of
reaction kinetics for sulfonation of
maleic, fumaric, and acrylic acids by
sulfite addition and for hydration of
acrylic acid with catalysis by H2S04 or
cation exchange resin. The kinetics were
measured by sampling isothermal batch
reactors.
Sulfocarboxylic Acids
In sulfonation experiments, the extent
of reaction was determined by iodine
titration for total sulfite. Solutions initially
containing 0.05-0.20 M unsaturatedacid
were maintained at approximate pH
values by lactate, acetate, or phosphate
buffers. NaCI, CaCI2, or MgCI2 was added
to change the ionic environment.
The sulfonation reactions follow a
second-order mechanism:
rate (M/min) = k( [acidhotai [SOshotai
The measured second-order rate
constants, kfM~1 min"1), for sulfonation at
1.2 N ionic strength in Na+ solutions at pH
5 are given by:
acrylic acid: k, = 4.48x 108exp(-14,000/RT)
fumaric acid: k( = 372 exp (-6,100/RT)
maleic acid: k, = 2.38 x 1011 exp(-17,500/RT)
where T is temperature (K) and R is the
gas constant (1.987 cal/gmol K). At 55°C
with 0.5 N ionic strength, the constants
are 0.21 M"1min"1 for acrylic, 0.031 M"1
min"1 for fumaric, and 0.52 IvT'min"1 for
maleic acids.
The rate constants do not vary signifi-
cantly from pH 3.5 to 7.0, but no reaction
occurs at pH 2 or 13. The sulfonation
rates increase with ionic strength. With
fumaric and maleic acids, there may also
be an additional catalytic effect of Mg++ or
Ca++.
Because dissolved sulfite is present in
a typical CaO/CaCOa scrubber system, it
is conceivable that unsaturated acids
would sulfonate if added directly to the
scrubber system. For the sulfonation
reactions, a scrubber system can be
characterized as a completely stirred tank
reactor with a residence time equal to the
ratio of solution inventory and the rate of
loss of solution with the waste solids.
Assuming 10 mM total dissolved sulfite,
55°C, 0.5 N ionic strength, and 130 hours
residence time, the fraction of unsulfo-
nated acid that would leave the system is
6% for acrylic, 29% for fumaric, and 4%
for maleic acids. Therefore, in situ
sulfonation is feasible for acrylic and
maleic acids, but it is only partially
effective for fumaric acid.
Acrylic acid and maleic anhydride (the
commercial form of maleic acid) require
some precautions for safe handling. If
these precautions are unacceptable to
the user, these unsaturated acids can be
easily sulfonated off site by reaction with
sodium sulfite. Sodium sulfosuccinate
was prepared successfully by adding 3.3
gmol Na2S03 and 3.0 gmol maleic
anhydride to 1 liter of water. The
temperature increased from 25 to 80°C
and the solids dissolved within 1'minute.
The solution did not precipitate when
cooled to 6°C. Therefore, the sulfonated
acids could probably be prepared in a tank
car and shipped as concentrated solution
directly to the user.
Hydroxypropionic Acid (HP)
In hydration experiments, acrylic acid
(AA) was determined by ion exclusion
chromotography (ICE) on a Dionex ion
chromatograph. HP was evident on the
chromatograms, but was not quantified
because of the lack of an adequate
standard. Hydration was catalyzed at 100
to 140°C by 0.1 to 1.5 M H2SO4 or by H+-
loaded sulfonated polystyrene resin
(Dowex 50W-X4) with an exchange
capacity of 1.3 meq/cm3 (wet basis) and
67% moisture content.
The hydration reaction was found to be
first-order in AA and first-order in H+. The
second-order forward rate constant, kf
(M~1hr~1), for both resin and H2S04
catalysis, was correlated by:
k, = 1.14 x 109 exp (-17,000/RT)
The reaction is reversible at high conver-
sions, where the net reaction is given by:
rate (M/hr) = k{Hl [AA] - kf/KlH*] [HP]
The equilibrium constant K is defined by:
K = [HP] / [AA]
In 1942, K was found to be 11.3 at
110.6°Cand6.8at 134°C.
In at least one experiment (105°C, 4 M
AA, 0.5 M H2SO4), there was visual
evidence of AA polymerization, giving a
faster apparent rate constant. Polymeri-
zation should be minimized by reduced
AA concentrations and increased catalyst
concentrations.
Using the 1942 measured ratedata and
equilibria, the estimated reactor residence
times for 85% conversion with 1 M H2S04
at 105°C are 14 hours for a batch or plug
flow reactor, 85 hours for a single
completely stirred tank reactor (CSTR),
and 33 hours for two CSTRs in series. If
the reaction was carried out at the
scrubber site, no additional purification
should be required, but there would be a
makeup requirement for sulfuric acid.
Specific results with HP synthesized
from AA in 1982 indicate that it inhibits
limestone dissolution. Inhibition probably
results from polyacrylic acid formed
during hydration. In actual operation, the
polyacrylic acid may be removed from
scrubber solution by precipitation of its
calcium salt. If not, removal of polyacrylic
acid by other means may be necessary.
Gas/Liquid Mass Transfer
Enhancement
I n 1981, S02 absorption was measured
at 25°C in a continuous stirred reactor
with an unbroken gas/liquid interface.
P«o2, pH, and concentrations of acetic and
adipic acids in 0.3 M NaCI were varied.
Because S02 absorption was quantified
by liquid-phase material balance, there
-------
were no experiments with greater than 1
mM total dissolved sulfite.
The apparatus used in the 1981
measurements (above) was modified for
this work. Heating tape was added to
liquid and gas stream inlets to permit
operation at 55°C. Gas-phase analysis
and flow measurement were refined, and
SOz absorption rate was determined by
gas-phase material balance, permitting
operation with high concentrations of
sulfate and total sulfite: Tighter pH
control was achieved by continuously
adding 1.0 M NaOH directly to the
reactor.
The apparatus was characterized at
55°C and 540 rpm by S02 absorption into
0.3 M NaOH giving a gas/film mass
transfer coefficient (kgA) of 4.93 x 10~3
gmol/bar-sec and into 0.3 M HCI giving a
liquid-film mass transfer coefficient (tfA)
of 1.5 x 10~3l/sec, where A is the
apparent surface area for mass transfer.
Experiments were performed in 0.3 M
NaClorO.1 MCaCI2atpH5.5or4.2withO-
40 mM of adipic, acetic, sulfopropionic,
sulfosuccinic, or hydroxypropionic acid or
AlCla. The gas-phase SOz concentration
was adjusted to give about 1000 ppm at
the gas/liquid interface. The enhance-
ment of the liquid/film mass transfer
coefficient by chemical reaction was
calculated from SOz absorption rate, S02
gas concentration, SOz Henry's constant,
I?A, and kgA as in the 1981 measurements.
In 1981, an enhancement factor model
was developed, based on approximate
surface renewal with multiple equilibrium
reactions. The model included equilibria
among and diffusion of the solution
species: H+, S0a, HSOs, SOS, HjA, HA',
and A=. The pk. values of the buffer
species, H2A, HA", and A*, could be
adjusted to represent any appropriate
buffer.
The 1981 model was used in this work
with appropriate equilibrium constants
and diffusivities to represent operation at
55°C in 0.3 M NaCI or 0.1 M CaCI2.
Empirically, it was found that diffusivities
in 0.1 M CaClz were consistently less
than in 0.3 M NaCI. To get good correlation
of the experimental data, the diffusivities
of all monovalent anions were reduced
25% and the diffusivities of all divalent
anions were reduced 45% from their
values in 0.3 NaCI.
The calculated values of the liquid/film
enhancement factor are within 10% of
the measured values for adipic, acetic,
sulfosuccinic, and hydroxypropionic
acids. To fit the measured data, the
diffusivity of sulfopropionic acid was
reduced by an additional 50% from the
value estimated in 1981.
Experiments with up to 20 mM AICI3 in
0.1 MCaClz at pH 3.8 gave no measurable
enhancement of SOz absorption, even
though basic AICI3 is an excellent buffer
at pH 3.8. The lack of effectiveness of the
aluminum buffer may result from the
formation of large, slow-moving polynu-
clear aluminum complexes, or it may
reflect a slow reaction rate between
aluminum complexes and H+.
Figure 1 shows the calculated liquid/
film enhancement factor for five buffers
as a function of buffer concentration in
0.1 M CaCI2 at pH 5.5 with 1000 ppm SOz
at the gas/liquid interface. On a molarity
basis, adipic acid is most attractive, and
sulfopropionic acid is least attractive.
With no buffer, the enhancement factor is
7.3 because of the hydrolysis of SOz and
because of enhancement by SOI. At 10
mM total adipic acid, the enhancement
factor is 20, or about 3 times greater than
in the absence of buffer.
Figure 2 illustrates the effect of adipic
acid on the overall enhancement of SOz
absorption. It gives the ratio of the overall
mass transfer coefficient, Kg, to the
gas/film coefficient, kg, as a function of
the dimensionless liquid-phase driving
force, (HP.o2 + [HA"] + 2[A"])/HP.02,
where H is the Henry's constant, Pso? is
the bulk gas SOz partial pressure, and
HA" and A* represent H adipate and
adipate species. The overall coefficient
includes an effect of tf and the liquid/film
enhancement factor which increases
with adipic acid concentration. The ratio.
Kg/kg, representing the fraction resistance
of the gas film, cannot exceed 1.0.
Greater values of Kg/kg represent
proportionately better scrubber perform-
ance. This specific figure is valid for
scrubbers with the ratio of mass transfer
coefficients without enhancement given
by H kVkg equal to 0.2.
As shown in Figure 2, adipic acid has a
greater effect with higher SOz gas
concentration because, at lower concen-
tration, SOz absorption is already con-
trolled mostly by gas/film resistance.
With less total dissolved sulfite, liquid/
film resistance is reduced by SOz hydroly-
sis to H* and HSOs, even in the absence of
buffer.
In all cases, the curves asymptote to
gas-phase control with an abscissa value
of 10 - 40.10 mM adipic acid and 10 mM
sulfite at pH 5 with 2500 ppm SOz gives
Kg/kg of 0.91. This corresponds to an
improvement of 1.8 because of adipic
acid addition.
Table 1 gives the calculated concentra-
tions of 12 buffers required to get an
enhancement factor of 20 in 0.1 M CaClz
with 10 mM total sulfite at pH 5.0 with
a32
£2S
V.
I 24
?
I 20
"
"
.
3
10
Adipic •
Sulfosuccinic
Acetic
' Hydroxypropionic -
• Sulfopropionic
i
5 10 15
Buffer Concentration, mM
20
Figure 1.
Calculated effect of buffer alter-
natives on the liquid/film en-
hancement factor, 0.1 M CaCli,
55°C. pH5.5,3 mM totalsulfite,
1000 ppm SOzi.
1000 ppm SOz at the gas/liquid interface.
Relative costs are calculated assuming
that makeup rates are proportional to
concentration.
Formic and acetic acids are most
attractive, but would probably be volatile
under scrubber conditions. Succinic and
lactic acids would not be cost-effective if
purchased at market price. Fumaric acid
is more subject to oxidative degradation.
Phthalic and benzoic acids may give
undesirable aromatic degradation pro-
ducts. Therefore, the most useful buffers
appear to be hydroxypropionic, sulfosuc-
cinic, sulfopropionic, adipic, and hydroxy-
acetic acids.
Waste or byproduct organic acids could
be cost-effective alternatives. Adipic acid
production by nitric acid/oxidation of
cyclohexanol/cyclohexanone generates
a byproduct consisting of glutaric, succinic,
and adipic acids which should perform
like adipic acid. Air-oxidation of cyclohex-
ane, to produce cyclohexanone as an
intermediate for caprolactam, generates
a byproduct solution of adipic, hydroxyva-
leric, glutaric, and other acids. The per-
formance of this product should be
comparable to a mixture of adipic and
hydroxypropionic acids.
Oxidative Degradation
Adipic acid and other carboxylic acids
are usually stable to oxidation in aqueous
-------
0.4
5 10 15 20
Liquid-Phase Driving Force
40
Figure 2. Overall mass transfer enhancement by adipic acid, 55°C, 0.1 M CaC/z. pH 5.
solution. However, free radicals generated
in the oxidation of hydrocarbons or
alcohols will attack carboxylic acids that
are present, producing CO2 and mono- or
dicarboxylic acids of shorter chain length
than the original acid.
Such conjugated oxidation of sulfite
and adipic acid results in degradation of
adipic acid to CO2 and shorter chain acids
(e.g., glutaric and valeric acids). The rate
of degradation is directly proportional to
the rate of sulfite oxidation and the total
organic acid concentration ([A]):
d[A]=kdrA]d[SOl]T
dt dt
Table 1. Relative Costs of Organic Acids ( =20,55°C. pHS.0.0.1M CaClz. 10mM Total Sulfite,
1000 ppm SO2J
Organic Acid
Formic
Acetic
Hydroxypropionic
Sulfosuccinic
Sulfopropionic
Adipic
Phthalic
Benzole
Fumaric
Hydroxyacetic
Succinic
Lactic
Concentration
21.1
15.6
19.7
16.3
25.6
11.8
18.1
17.9
19.1
32.0
12.3
34.4
Price
f$/lb mol)
12.28
21.62
34.59
43.15
34.59
77.45
55.58
57.46
66.16
39.66
134.11
78.82
Relative
Cost
0.28
0.37
0.75
0.77
0.97
1.00
i.fo
1.13
1.38
1.39
1.80
2.97
Pilot, prototype, and demonstration plant
tests of adipic acid have shown significant
levels of degradation. The degradation
losses are generally reduced at pH less
than 5.0 and increased by forced oxida-
tion.
The objective of this work was to
quantify the rates and products of the
degradation of adipic acid and alternative
carboxylic acids. Parallel work by Radian
Corporation has measured rates and
products of adipic acid degradation.
In this work, degradation of 5 - 20 mM
carboxylic acid was measured during
batch oxidation of 1 - 2 M CaSOs slurry at
55°C with pure oxygen sparged into an
agitated reactor. Slurry was analyzed for
total sulfite by iodine titration. Filtered
solution was analyzed for specific car-
boxylic acids by ion (or ion exclusion)
chromatography. Additional solution
analyses were performed by gas chroma-
tography with extraction into chloroform
before and after aqueous methylation.
FigureS gives typicaI resuIts on the rate
of sulfite oxidation. At pH 4.3 or 4.5 or
with 1 mM Mn, the sulfite oxidation rate
was maximum, limited by either mass
transfer or the supply of Oz to the reactor.
Without Mn, the sulfite oxidation rate
decreased with increasing pH and
essentially stopped at pH 6.0.
Both hydroxycarboxylic acids and thio-
sulfate inhibited sulfite oxidation. At pH
5.0, 0.3 mM Mn was sufficient to
compensate for inhibition by 10 mM
hydroxyacetic acid. With 1 mM Mn,
sulfite oxidation was completely inhibited
by 2 mM thiosulfate at pH 5.5, and by 3
mM thiosulfate at pH 5.0. 10 mM
thiosulfate was insufficient to inhibit
sulfite oxidation at pH 5.0 in the presence
of 1 mM Mn and 0.3 M MgSCh.
Figure 4 gives the degradation rate
constant (kd) of adipic acid as a function of
pH with and without Mn. In the absence
of Mn, kd is only a weak function of pH.
With 1 mM Mn,kd is significantly reduced
and is a strong function of pH. At pH 4.5,
the degradation of succinic acid was
almost completely inhibited by 0.3 mM
Mn, but hardly affected by 0.2 mM Mn.
These data are generally consistent
with degradation rates measured at both
theShawnee 10 MW test facility and the
Radian bench-scale scrubber in 1982.
No adipic acid degradation was observed
in experiments with no sulfite oxidation,
resulting from high pH or the presence of
hydroxyacids or thiosulfate. At pH 5.5
with 1 mM Mn, the presence of 1 mM
thiosulfate reduced kd from 0.6 to 0.25 M~1,
while hardly affecting the rate of sulfite
oxidation.
-------
I
.o
I
Without Mn
With 1 mM Mn
0.05 —
0.02
5.0
5.5
pH
acid impurities that would probably have
to be separated. Glycolic acid is commer-
cially available, but economically some-
what less attractive.
4. Sulfosuccinic acid is economically
attractive when synthesized in situ or
offsite from maleic anhydride. It is subject
to oxidation, but should give nonvolatile
degradation products.
5. Basic aluminum salts are ineffective
for mass transfer enhancement.
Figure 3. Effect of pH on sulfite oxidation— 1340 rpm, 200 ml Oz/min.
Table 2 compares degradation rate
constants measured for eight organic
acids. The aliphatic acids (succinic,
glutaric) and sulfoacids (sulfopropionic,
Sulfosuccinic) behaved much like adipic
acid. Dibasic waste acid (mostly glutaric)
also degraded like adipic acid. Fumaric
acid degraded much faster than adipic
acid because of its carbon-carbon double
bond. The hydroxyacids both degraded
much more slowly, probably because of
the alcohol function. In one experiment
with a mixture of hydroxyacetic and
adipic acids, the adipic acid degraded as
usual, but the hydroxyacetic acid degraded
much more slowly than adipic acid.
Table 3 gives the typical degradation
products of adipic acid at pH 5.0 with and
without Mn. With Mn, there are nominal
concentrations of the expected products,
• ileric and glutaric acids. Without Mn,
;re is also an appreciable accumulation
.. the aldehyde-acid, 4-carboxybutanal.
In both cases most of the adipic acid that
degrades is probably lost as C02.
Conclusions
1. Adipic acid was attractive buffer
properties, and is cost-effective, non-
toxic, and commercially available in large
quantities. It coprecipitates with CaSOs
and is subject to oxidative degradation,
but these problems should be minimized
by using forced oxidation at low pH with
high concentrations of dissolved Mn.
2. Byproduct dibasic acid (DBA), con-
taining primarily glutaric acid, is a cost-
effective alternative equivalent to adipic
acid.
3. The hydroxycarboxylic acids are
uniquely inert to oxidative degradation
and inhibit sulfite oxidation in the
absence of Mn. Hydroxypropionic acid is
economically attractive; however, its
synthesis from acrylic acid gives polyacrylic
-------
2.0
1.0
0.8
0.6
c
f 0.4
3
0.1
0.3 to I.OmMMn
4.0
Figure 4. Adipic acid degradation.
5.0
pH
6.0
Table 2. Measured Degradation Rate
Constants of Buffer Alternatives
Mn, ka.
Organic Acid pH mM /1/T1
Adipic
Glutaric
Succinic
Sulfopropionic
Sulfosuccinic
Fumaric
Hydroxyacetic
Hydroxypropionic
4.5
5.5
5.5
4.5
5.0+
5.0+
5.5
5.0
4.5
0.0
1.0
0.0
1.0
0.1
0.0
0.0
0.0
1.0
0.3
0.0
0.8
0.15
1.6
0.6
1.6
0.5
1.0
1.0
2.4
0.1
0.2
Table3. Organic Acids in a Solution of 10
mM Adipic Acid Degraded at pH
5.0
Concentrations. mM
Product
Adipic
Glutaric
Unknown 117(05)
4 - Carboxy-butanal
Succinic
Malonic
Valeric
Unknown 422 (C4)
Butyric
Carbon lost (COz)
Mn,
0.1 mM
1.40
0.55
0.50
2.50
0.20
0.50
0.09
0.40
0.06
29.3
Mn,
3.0 mM
5.20
0.45
-
0.04
0.04
0.50
0.03
0.03
23.5
G. Rochelle, R. Smith, W. Weems, M. Hsiang, and Y. Lee are with the University
of Texas, Austin, TX 78712.
J. David Mobley is the EPA Project Officer (see below).
The complete report, entitled "Buffer Additives for Lime/Limestone Slurry
Scrubbing Synthesis, Mass Transfer, and Degradation," (Order No. PB 84-184
233; Cost: $23.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
. * Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
U.S. GOVERNMENT PRINTING OFFICE: 1984-759-102/
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