United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-84-060 Apr. 1984
&ERA Project Summary
Equilibrium Distribution
Coefficients for Extraction of
Organic Priority Pollutants
from Water
C. Judson King, Timothy A. Barbari, Dilip K. Joshi,
Nancy E. Bell, and John J. Senetar
i i
Equilibrium distribution coefficients
have been determined for extraction of
acrolein, acrylonitrile, N-nitrosodi-
methylamine, isophorone, 2-chloro-
phenol, bis(2-chloroethyl)ether,
bis(2-chloroethoxy)methane, phenol,
resorcinol, pyrogallpl, and nitrobenzene
from water into a variety of solvents in-
cluding paraffins, aromatics, ketones,
esters, ethers, phosphates, chlorinated
hydrocarbons, alcohols, carboxylic
acids, and amines. These results are in-
terpreted in terms of Lewis-acid, Lewis-
base concepts.
Equilibrium distribution coefficients
are also measured for extraction of
benzene, toluene, ethylbenzene, chloro-
benzene, 1-2 dichloroethane, 1-1-1 tri-
chloroethane, 1-1-2-2 tetrachloroethane,
1-2 dichloropropane, 1-2trans-dichloro-
ethylene, trichloroethylene, tetrachloro-
ethylene, and bromoform from water
into undecane, modeling kerosene as a
solvent. In all cases, values of distribu-
tion coefficient are high enough to make
extraction into kerosene an attractive
removal process.
Vapor-liquid equilibrium data and
results of 72-hour stability tests are
reported for mixtures of acrolein or
acrylonitrile with several candidate
solvents. On the basis of the experimen-
tal results likely attractive solvents are
identified.
Conceptual process designs and eco-
nomic analyses are carried out for a
number of solvent/solute systems, and
result in projected costs (1982 dollars) of
$1.10 to $3.20 per mj of water ($4.20 to
$12.20 per 1000 gallons of water) for
removal of solutes present at 200 to 1000
ppm levels in water.
This Project Summary was developed
by EPA's Robert S. Kerr Environmental
Research Laboratory, Ada, OK, to an-
nounce key findings of the research pro-
ject that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back}.
Introduction
The U.S. Environmental Protection
Agency (EPA) has established a list of 129
Priority Pollutants, upon which primary em-
phasis, is being placed for development of
reliable and precise analytical techniques and
evaluation of appropriate control technology.
This information serves as necessary back-
ground for the identification of the Best
Available Control Technology Economically
Achievable (BATEA).
Although not yet one of the most com-
mon approaches used as control technology,
solvent extraction holds good potential for
removal of many of the organic Priority
Pollutants from effluent water streams. Sol-
vent extraction can be attractive in cases
where the solutes are toxic or nonbiode-
gradable, where the solutes are present at
high enough concentrations to provide eco-
nomic recovery value, and/or when steam
stripping would be complicated or precluded
by low solute volatility and/or formation of
azeotropes with water. Solvent extraction
can also be a broad-brush removal process
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for dissolved organics in cases where an in-
expensive solvent gives large equilibrium
removals of the spectrum of solutes present.
Solvent extraction has been used for many
years for recovery of phenols from aqueous
effluents from coke ovens in the iron and
steel industry, and is a likely component of
processing systems for condensate waters
from coal gasification or liquefaction.
The purpose of this project was to es-
tablish phase-equilibrium data necessary for
evaluation of solvent extraction as a treat-
ment and/or recovery process for a large
number of non-polar and polar organic Prior-
ity Pollutants in aqueous streams. Factors
considered in choosing the particular polar-
organic Priority Pollutants to be studied were
solubility in water, nonbiodegradability, dif-
ficulty of stripping, and the presence of func-
tional groups which might lead to specific
interactions with certain solvents. The
solutes considered are listed in Table 1. The
principal piece of information sought has
been the equilibrium distribution coefficient,
KD, defined as the weight fraction of solute
in the solvent phase divided by the weight
fraction of solute in the aqueous phase, at
equilibrium and at high dilution. Higher
values of KD lead to less solvent flow being
required in proportion to the water flow rate,
and thereby usually lead to less expensive
extraction processes, provided that solvent
regeneration can be achieved economically.
Lewis-acid or Lewis-base complexes with
solutes were explored to find solvents that
give high values of the equilibrium distribu-
tion coefficient.
For certain solute-solvent systems vapor-
liquid equilibrium data were measured to
Table 1. List of Priority Pollutants
Investigated in This Work
Acrolein
Acrylonitrile
Benzene
Bromoform
Chlorobenzene
bisl2-Chloroethoxy)methane
bis!2-Chloroethyl)ether
2- Chlorophenol
1,2-Dichloroethane
1,2- trans-Dichloroethylene
1,2-Dichloropmpane
Ethylbenzene
Isophorone
Nitrobenzene
N-Nitrosodimethylamine
Phenol
Pyrogallol
Resorcinol
1,1,2,2-Tetrachloroethane
Tetrachloroethylene
Toluene
1, J, 1-Trichloroethane
Trichloroethylene
determine the ease of solvent regeneration
by distillation. Also, 72-hour stability tests
were made with certain solvent-solute mix-
tures to determine if the solvent degraded
or reacted with the solute.
Based on the experimental data, likely at-
tractive solvents were identified. Preliminary
process designs for the integrated process
(consisting of extraction, regeneration, and
raffinate stripping) were done, and economic
analyses were carried out to determine the
cost of extracting these chemicals from
water.
Equilibrium Distribution
Coefficients
Equilibrium distribution coefficients for
particular solute/solvent systems were
measured by contacting predetermined
amounts of highly dilute aqueous solute-
containing feeds and solvents in flasks
agitated in a mechanical shaker. The phases
were allowed to settle, and the raffinate was
centrifuged. Samples of aqueous feed and
raffinate were analyzed by flame-ionization
gas chromatography using Porapak columns
or by HPLC using C18^-Bondapak columns.
The equilibrium distribution coefficient (KD
= Wt. fraction solute in solvent phase/wt.
fraction solute in aqueous phase) was
calculated assuming complete material
balance. Precautions were taken against
solute and solvent losses by vaporization dur-
ing handling.
Two approaches were used for solvent
selection. Extraction with undecane (model-
ing kerosene) was investigated as an effec-
tive broad-brush process for generic removal
of chlorinated hydrocarbons and aromatics
from water. For the more polar organic
solutes, the solvent had to be selected
specifically for its compatibility with the
solute of interest, rather than for broad-brush
removal purposes. Lewis-acid, Lewis-base
interactions were explored to gauge which
solvents would complex with the solute.
Lewis-acid solvents included alcohols, car-
boxylic and phosphoric acids, chlorinated
hydrocarbons with active hydrogen atoms,
aromatics, and dienes. Lewis-base solvents
included amines, ketones, esters, ethers, and
phosphates. Commercially available solvents
representing these groups were evaluated.
Aromatics and Halogenated
Hydrocarbons
Table 2 lists the measured equilibrium
distribution coefficients for extraction of
aromatics and halogenated hydrocarbons
from water into undecane. The generally
high values of KD for these compounds
serve to make kerosene and related mixtures
attractive solvents for removing them from
aqueous effluent streams. The high values
of KD allow relatively low ratios of solvent
flow to water flow to be used as an extrac-
tion process for water treatment. Low sol-
vent-to-water ratios can be used effectively
in certain types of extractors, such as mixer-
settlers and reciprocating-plate columns; low
solvent flows reduce costs for solvent re-
generation.
This phase of the project is described in
more detail by T.A. Barbari and C.J. King,
Environ. Sci. and Techno/., 16, 624-627
(1982).
Phenolic Compounds
An abundant body of information exists
in the published literature on extraction of
phenols from water, which has been prac-
ticed on a large scale for many years in con-
nection with coke-oven waters. Therefore,
the goal of this portion of the study was to
develop data for a few additional solvents
which could be of interest. The additional
solvents considered were tricresyl phosphate
with and without various diluents, tertiary
amines, and trioctylphosphine oxide (TOPO).
The measured distribution coefficients are
summarized in Table 3.
Tricresyl phosphate (TCP) gave high KD
for phenol. TCP had toxic properties, how-
ever, and therefore it is not recommended
for use as a solvent for waters that are to
be released. Diisobutyl ketone (DIBK) was
found to be a good diluent. Resorcinol and
pyrogallol are more difficult to remove than
phenol, due to the presence of more hy-
droxyl groups. For the tertiary amine
(Alamine 336), KD was a strong function of
the diluent employed, with 2-ethyl hexanol
giving the highest value of KD for resor-
cinol. However, values of KD measured for
extraction into pure 2-ethyl hexanol are
nearly as large, thereby indicating that the
benefit from complexing the phenols with
the amine is not great.
Trioctylphosphine oxide (TOPO) is known
to complex strongly with phenol. For extrac-
tion of pyrogallol with a solvent composed
of 25 wt% TOPO in DIBK, very high values
of KD are observed. However, DIBK may
not be the best diluent from a volatility
standpoint.
Acrolein
Acrolein is an a-/} unsaturated aldehyde,
and has a Lewis-acid site due to the de-
localized electrons, as well as a Lewis-base
site at the carbonyl oxygen. Thus both
Lewis-acid and Lewis-base solvents may be
suitable. Table 4 lists some of the measured
distribution coefficients. Alcohols and car-
boxylic acids have rather low values of KD,
probably due to self-association. Ketones
and esters give attractively high values of
KD. Tradeoffs between distribution coeffi-
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Table 2. Experimentally Measured Equilibrium Distribution Coefficients for Extraction
from Water into Undecane, 295-300 K
Mean
Benzene
Toluene
Ethylbenzene
Chlorobenzene
1,2-Dichlorobenzene
Chloroform
Carbon tetrachloride
1, 1-Dichloroethane
1,2-Dichloroethane
1, 1-Trichloroethane
1, 1,2,2-Tetrachloroethane
1,2-Dichloropropane
1,2-trans-Dichloroethy/ene
Trichloroethylene
Tetrachloroethylene
Bromoform
214
740
2500
845
3030
74.7
738
41.0
25.0
414
110
73.6
119
354
2700
127
KD = Wt. fraction solute in so/vent phase/
wt. fraction solute in water phase,
at equilibrium and high dilution.
Table 3.
Measured Distribution Coefficients (KD) for Extraction of Phenolic Compounds
from Water
Solute
Phenol
Resorcinol
Pyrogallol
2-Nitrophenol
Solvent
Tricresyl Phosphate (TCP)
25% v/v TCP + DIBK
25% v/v TCP + 2-Ethylhexanol
25% v/v TCP + Chevron 25
TCP
50% v/v Alamine 336 +
2-Ethylhexanol
50% v/v Alamine 336 + DIBK
50% v/v Alamine 336 + Chevron 25
2-Ethylhexanol
TCP
50% v/v Alamine 336 +
2-Ethylhexanol
2-Ethylhexanol
25% wt/wt TOPO + DIBK
TCP
Mean KD
73
85
51
17
11.6
4.0
3.2
0.8
3.7
1.47
0.9
0.7
110
203
KD = Wt. fraction solute in so/vent phase/wt. fraction solute in aqueous phase at equilibrium and
high dilution.
cients and solubility in water may be con-
sidered by choosing solvents occupying
different positions in the homologous series.
Aromatic compounds and chlorinated hydro-
carbons with active hydrogen atoms are
good solvents but are themselves pollutants.
Residual solvent must therefore be removed
from the raffinate. Tributyl phosphate shows
a reasonably high value of KD, but not high
enough to warrant use of this more expen-
sive and high-boiling solvent. Primary and
secondary amines give very large degrees of
extraction for acrolein, but back-extractions
and kinetic measurements confirmed that
this was due to a slow, irreversible chemical
reaction. Mixed solvents containing both
acidic and basic components did not show
any special advantages.
Acrylonitrile
Acrylonitrile has Lewis-base properties due
to the cyano group, and Lewis-base proper-
ties due to a-p unsaturation. Thus, both
Lewis acids and bases are potentially attrac-
tive as solvents.
Carboxylic acids and alcohols show rather
low values of KD. Ketones, esters,
aromatics, and chlorinated hydrocarbons
give higher values. Amines are rather poor
solvents. Mixtures of TOPO and DIBK did
not show significant advantage over DIBK
alone. Tributyl phosphate was found to be
an effective solvent. However, it is more ex-
pensive and high-boiling, and its solubility in
water depends on the diluent used. Several
diluents for tributyl phosphate were evalu-
ated. Also mixed solvents containing
di-2-ethylhexyl phosphoric acid (D2EHPA)
and various bases were investigated, but
they did not have significant advantages. In
general, the distribution coefficient with a
given solvent was higher for acrylonitrile than
for acrolein; this is a direct result of the lower
solubility of acrylonitrile in water. Table 4 is
a partial listing of the measured distribution
coefficients for acrylonitrile.
N-Nitrosodimethylamine
(NNDMA)
There is significant charge separation in
the resonance hybrid of NNDMA. The oxy-
gen atom has Lewis-base properties, while
the positive nitrogen atom has Lewis-acid
properties. Because of steric hindrance
about the positive nitrogen atom, the mole-
cule should have more ability to act as a
Lewis base. The observed value's of distribu-
tion coefficients for extraction of NNDMA
are quite low, which is a result of the strong
interaction with water. Alcohols, carboxylic
acids, phosphoric acids, phosphates, ethers,
and amines are rather poor solvents for
NNDMA. Chlorinated hydrocarbons, ke-
tones, aromatics are better solvents, but only
methylene chloride has a sufficiently high
value of distribution coefficient (2.6) to make
an extraction process feasible.
Isophorone
Isophorone has a structure similar to that
of acrolein. Thus, both acidic and basic
solvents are potential candidates. The values
of distribution coefficients for extraction of
isophorone are much higher than for acrolein
due to the lower solubility and thus, the
higher activity coefficient in water. Several
mixtures of conventional solvents were
tested. Mixtures of neo-decanoic acid with
DIBK or toluene as diluent gave distribution
coefficients higher than those for the in-
dividual components. These results can be
explained on the bases of diminished di-
merization of neo-decanoic acid, separate in-
teractions with the basic and acidic sites on
isophorone, and/or enhancement of basici-
ty or acidity.
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Table 4. Values of Weight-Fraction-Based Equilibrium Distribution Coefficient (KD) Measured for Extraction of Organic Solutes from Water into
Various Solvents, at High Dilution and Ambient Temperatures
2-Chloro-
Solvent/ Solute Acrolein Acrylonitrile NNDMA Phenol Isophorone Nitrobenzene b2CEE b2CEM
Alkane:
n-Undecane
Aromatic:
Toluene
Ketones:
Methyl Isobutyl
Diisobutyl
Isobutyl Heptyl
Esters:
n-Butyl Acetate
n-Hexyl Acetate
n-Octyl Acetate
Isobutyl Isobutyrate
Ethers:
Diisopropyl
Di-n-butyl
Phosphates:
Tri-n-butyl
Tricresyl
Chlorinated HCs:
Methylene Chloride
Chloroform
1,1,2,2-Tetrachloro-
ethane
Alcohols:
1-Octyl
2-Ethylhexyl
Acids:
2-Ethylhexanoic
Neodecanoic
Di-2-ethylhexyl
phosphoric
0.44
2.1
4.9
1.60
0.93
2.5
2.1
1.7
1.98
1.7
1.08
1.98
1.7
6.6
6.5
4.6
-
7.25
0.5
-
(1.3)
0.15
3.46
6.5°
3.52
1.2
5.4
3.5
-
3.5
2.6
3.2
5.3
2.7
8.6
-
7.2
-
1.71
1.6
-
2.58°
10.8 10.2
0.68 - 88
0.63 600 82
390 62
(0. 1) 159
0.6
-
_
-
0.27
-
0.3" 2600 48
1200
2.6
_ _
-
0.34
0.3
0.42
39
0.43* - 26
37 11.0 12.4
350
117
280 70 116
50
-
-
-
-
-
- -
290 83 125
-
_
_ _
-
_
-
_
_
_
8 - Possible irreversibility or slow kinetics, or impurity effect.
b - 50 vol % mixture in n-undecane.
c - 50 vol % mixture in diisobutyl ketone.
Nitrobenzene
The nitro group on the ring serves to
withdraw electrons and makes the molecule
a strong pi-electron acceptor. Lewis-base
solvents (ketones, phosphates) and aromatic
solvents have quite high and reversible
distribution coefficients for extraction of
nitrobenzene.
Chlorinated Ethers
The ether linkages are weakly basic, but
the greater effect comes from the influence
of the electronegative chlorine atoms, mak-
ing adjacent hydrogen atoms available as
electron acceptors. Thus, Lewis-base sol-
vents (ketones and phosphates) give en-
hanced values of distribution coefficients.
Vapor Liquid Equilibria
Vapor-liquid equilibrium measurements
were carried out using a vapor-recirculating
equilibrium still for binary mixtures of acrolein
or acrylonitrile with selected solvents. The
data show only modest departures from ide-
ality. All systems, except for the acro-
lein/methylene chloride system, proved to
be sufficiently wide-boiling so that regenera-
tion by distillation would not be very ex-
pensive.
Stability Tests
For mixtures of acrolein or acrylonitrile
with various solvents, stability tests were car-
ried out wherein the mixtures were heated
under controlled conditions (total-reflux
distillation at atmospheric pressure, or
holding the temperature at the desired value
in a water bath) for 72 hours.
Mixtures of acrolein with butyl acetate,
MIBK, and tetrachldroethane all generated
an opaque white solid upon refluxing at the
atmospheric boiling point of the mixture. The
white solid possessed properties equivalent
to those of acrolein polymer. Two ap-
proaches were investigated for discouraging
the formation of polymer. Lowering the
temperature during the stability test to 65°C
resulted in clear solutions, and losses of
acrolein were eliminated. Thus, vacuum
distillation could be a viable alternative for
regeneration. Adding hydroquinone as an in-
hibitor also resulted in elimination of
polymerization of acrolein. Use of hydro-
quinone (a pollutant, itself) would be un-
desirable for a water-treatment process
where the effluent is released to the en-
vironment.
In the case of mixtures of acrylonitrile with
solvents, yellow solids were formed during
heating of mixtures with MIBK, butyl
acetate, and toluene, probably due to a
cyanoethylation reaction. Di-n-butyl ether
also reacted with acrylonitrile. On the other
hand, TBP, methylene chloride, and tet-
rachloroethane were stable towards acry-
lonitrile at boiling temperatures.
Preliminary Designs and
Economic Analyses
Conceptual designs and economic
analyses were carried out for a number of
different solute/solvent systems. Results of
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these analyses are shown in Table 5. Both
low-boiling and high-boiling solvents were in-
vestigated. The integrated process includes
an extractor, a regenerator column, and a
vacuum steam stripping column for removal
of residual solvent from the raffinate, along
with appropriate heat exchangers.
Total costs (1982 basis) including capital-
related costs and interest, lie in the range of
$1.10 to $3.207m3 of water ($4.20 to $12.20
per 1000 gallons) for all cases except the
acrolein-toluene combination. The low-
boiling solvents lead to higher costs than for
the comparable high-boiling solvent cases,
because of steam costs associated with
regeneration. In some cases, however, the
use of high-boiling solvents may incur extra
costs for purge.
Conclusions
Equilibrium distribution coefficients for ex-
traction of chlorinated hydrocarbons and
aromatic compounds into undecane were all
high enough to make kerosene an attractive
solvent for removing these compounds from
water by solvent extraction.
For the more polar solutes investigated
(phenol, resorcinol, pyrogallol, 2-chloro-
phenol, 2-nitrophenol, acrolein, acrylonitrile,
nitrobenzene, isophorone, N-nitrosodi-
methylamine, chlorinated ethers) equilibrium
distribution coefficients into hydrocarbon
solvents are lower than those into weak or
moderately strong complexing extractants,
which can interact with the solute through
Lewis acid-Lewis base mechanisms. Vapor-
liquid equilibrium data for mixtures of
acrolein and acrylonitrile with various
solvents showed that regeneration by distilla-
tion will not be a problem for most of the
combinations considered. Stability tests for
mixtures of acrolein with various solvents
showed that polymerization of acrolein is a
potential problem, and can be avoided by
carrying out regeneration by vacuum distilla-
tion or by use of inhibitors. Stability tests also
showed that many promising solvents for
acrylonitrile had to be discarded due to a
cyanoethylation reaction. Recommended
low-boiling and high-boiling solvents for the
various solutes are listed in Table 6.
Conceptual designs and economic analy-
ses have been carried out for a number of
combinations of solutes and solvents giving
costs ranging from $4.20 to $12.20/1000
gallons of water ($1.10 to $3.20/m3).
Recommendations
Solvent extraction should be given more
serious consideration as an effective means
for removing problem pollutants from water.
It has particular advantages where a solute
is nonbiodegradable or toxic to biotreatment
systems, or where the concentration and
value of the solute are such that there is
economic incentive for recovering the solute.
In competition with stripping as a recovery
process, extraction has advantages when the
solute forms an azeotrope with water (as
does phenol), or where very high solvent
capacity can lead to a very low steam re-
quirement for solvent regeneration.
In the present work, solvent-stability tests
were carried out for only 72 hours, and for
only acrolein and acrylonitrile as solutes.
Before large-scale installations are built for
recovering these and other solutes by extrac-
tion, it will be desirable to carry out more pro-
tracted solvent-stability tests. Near-complete
regeneration and recovery of solvent are im-
portant for economic viability of extraction
processes for water treatment.
Solvent extraction is worthy of considera-
tion for removal of a variety of polar-organic
pollutants from water. Its possibilities extend
well beyond the particular solutes considered
in this project.
Table 5. Estimated Costs for Extraction of Polar Organics from Water
Solute Acrolein
Acrylonitrile
2CP
NB NB
So/vent
MIBK*
Butyl
Acetate
Toluene TCE
TCE
Methylene
Chloride
TCE
TCE
IBHK DIBK DIBK0
100,000 200
13.6 56.8
268 1112
Aqueous Feed
-Solute Concen- 200 200 200 200
tration (ppm)
-Flow Rate (rrf/h) 13.6 13.6 13.6 13.6
Fixed Capital
Investment - FCI
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Table 6.
Solvents Recommended on the Basis of Work in this Project*
Recommended Solvents
Solute
Low Boiling
High Boiling
Acrolein (53)
Acrylonitrile (78)
N-Nitrosodimethylamine
(152)
Isophorone (215)
2-Chlorophenol (176)
bis(2- Chloroethyllether
(178)
bis(2-Chloroethoxyi-
methane (218)
Nitrobenzene (211)
Chlorinated Hydrocarbons
Aromatic Hydrocarbons
Phenol (181)
Polyhydroxy Phenols
- e.g., Resorcinol (277);
Pyrocatechol (240)
Methylene Chloride (40)
Methylene Chloride (40)
(Toluene) (111)
Hydrocarbons
MIBK (117)
DIBK (168)
Toluene (111)
Hydrocarbons
MIBK (117)
Hydrocarbons
MIBK (117)
Hydrocarbons
DIBK (168)
Hydrocarbons
DIBK (168)
Hydrocarbons
Hydrocarbons
MIBK (117)
Diisopropyl Ether (68)
MIBK (117)
n-Butyl Acetate* (126)
MIBK* (117)
Tetrachloroethane* (146)
Toluene* (111)
TBP (289) + Hydrocarbon
(Tetrachloroethane) (146)
Hydrocarbons
TBP (289) + Hydrocarbon
Hydrocarbons
IBHK (218)
TBP (289) + Hydrocarbon
Hydrocarbons
TBP (289) + Hydrocarbons
IBHK (218)
Hydrocarbons
TBP (289) + Hydrocarbons
Hydrocarbons
TBP (289) + Hydrocarbons
Hydrocarbons
Hydrocarbons
TOPO/diluent
TBP (289)1 diluent
TOPO/diluent
(TBP (289)/diluent)
- Numbers in parentheses are atmospheric boiling points, °C.
Solvents in parentheses are less well evaluated.
C. J. King, T. A. Barbari, D. K. Joshi, N. E. Bell, andJ. J. Senetarare with University
of California. Berkeley. CA 94720.
Marvin Wood is the EPA Project Officer (see below).
The complete report consists of two volumes:
"Equilibrium Distribution Coefficients for Extraction of Organic Priority
Pollutants from Water—I," (Order No. PB 84-159 821; Cost: $10.00, subjectto
change).
Equilibrium Distribution Coefficients for Extraction of Organic Priority
Pollutants from Water—II. "(Order No. PB 84-159 839; Cost: $10.00, subject to
change).
The above reports 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:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
Ada, OK 74820
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
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ft U.S. GOVERNMENT PRINTING OFFICE: 1984-759-102/924
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