United States
                    Environmental Protection
                    Agency
Health Effects
Research Laboratory
Research Triangle Park NC 27711
                    Research and Development
 EPA-600/S1-84-025 Jan. 1985
4>EPA         Project Summary
                    Isolation  and  Concentration  of
                    Organic  Substances from
                    Water Using  Synthetic  Resins
                    and  Graphitized  Carbon  Black
                   E.S.K. Chian, J.H. Reuter, and M. Giabbai
                     This study describes the evaluation of
                   an integrated adsorption system for the
                   isolation and  concentration, not less
                   than 50 fold, of 22 specified organic
                   compounds at /ug/L levels. The system
                   was first developed and tested  on a
                   laboratory scale and then  adapted for
                   the processing of large volumes of
                   water (pilot scale).
                     With this system, dissolved organics
                   were separated into fractions by adsorp-
                   tion onto Amberlite XAD-8, AG MP-50
                   cation exchange resin, and graphitized
                   carbon  black (GCB) under varying pH
                   conditions.  Model compounds used in
                   the evaluation covered a broad spectrum
                   of physical  and chemical properties, so
                   that comparisons between this and
                   other concentration/isolation tech-
                   niques could be made.
                     A substantial effort was made to
                   establish analytical techniques for
                   monitoring  model compound recovery
                   in the proposed system. Quantification
                   was performed using GC, GC/MS and
                   HPLC.
                     In the laboratory-scale studies,  15 of
                   the 22  model compounds exhibited
                   recoveries varying from 30% to 90%. In
                   general, poorer recoveries were observed
                   for the  more volatile, polar, or water
                   soluble compounds. Recoveries of
                   model solutes appeared to be virtually
                   unaffected  by the presence of humic
                   acid (2 ppm) and inorganic salts.
                     The results of the final pilot experi-
                   ments with five 100-L  test solutions
                   confirmed  those  of the bench-scale
                   studies.  However, some  difficulties
                   with column flow and lower recoveries
were encountered. These problems
were attributed to humic acid break-
through on the XAD-8 column and the
subsequent coprecipitation of calcium
salts, humic acid and possibly other
organic substances at high pH.
  This Project Summary was developed
by EPA's Health Effects Research Labo-
ratory. Research Triangle Park, NC, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project report orderingin information at
back).

Introduction
  In recent years, organic waterborne
pollutants have  been identified  as
potential health hazards Epidemiological
studies have suggested a relationship
between the ingestion of these pollutants
in drinking water and carcinogenic and
teratogenic effects. Although hundreds
of organic compounds have been detected
and quantified in drinking water,  the
majority of organic material, i.e.  the
nonvolatile fraction-, cannot be identified
using currently available technology.
Therefore, the direct concentration/isola-
tion of organic contaminants in aqueous
samples for biological testing offers a
practical solution to the determination of
health risks associated with trace organic
contaminants.
  The Health Effects Research Laboratory
has funded several independent studies
in an effort to determine the effectiveness
of  different isolation/concentration
techniques.  Systems or techniques
investigated were reverse osmosis,

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vacuum distillation, solid adsorbents, and
supercritical fluid C02 extraction.  The
necessity of concentrating  aqueous
samples before an assessment of potential
health risks can be made, stems from the
lack of sensitivity for existing in vitro and
in vivo biological test systems.
  The following criteria must be considered
when attempting to  concentrate organic
substances from  potable water for
biological testing: 1) the aqueous organic
concentrate prepared by the selected
concentration scheme should have the
same relative abundance of the individual
components as the original water sample;
2) introduction of artifacts and constituent
alteration  by the concentration method
should  be kept to a  minimum; 3) altera-
tion  of the organic constituents  after
preparation of concentrates and before
biological testing and chemical analysis
must be avoided; 4) the effect of humic
material,  which constitutes  the bulk of
the organic fraction, on the recovery of
trace solutes has to be taken into account;
5) co-recovery of toxic inorganic constitu-
ents by the concentration scheme should
be avoided  and 6) effect  of chlorine
residual on the material used in the con-
centration scheme — resins, graphitized
carbon black, etc., must be assessed.
  These considerations,  as well as the
necessity for a comprehensive approach
toward the isolation and concentration of
dissolved organic carbon in water, led to
the investigation  of an isolation scheme
in which organic compounds with different
functionalities and sorption  parameters
were separated  and  concentrated. A
mixture of 22 model compounds proposed
by the Health Effects Research Laboratory
was  chosen for process evaluation. The
proposed  isolation  scheme  was  first
tested  on a laboratory scale  and then
adapted for processing several hundred
liters of water.
Procedur.e
Preparation of Model Compound
Test Solutions
  As shown in Table 1  stock solutions of
quinaldic acid, glycine and glucose were
prepared  in organic-free water (OFW).
Humic  acid was dissolved  in  0.02N
NaOH,  5-chlorouracil in 2N NH4OH, and
the remaining compounds in  methanol
except for phenanthrene; 1-chlorodode-
cane; 2,4'-dichlorobiphenyl; and 2,2',5,5'
-tetrachlorobiphenyl. The spiking of the
test solution with the latter  compounds
required  successive solubilization and
evaporation in hexane and acetone prior
to the addition of OFW. The test solutions
for the other model sol utes were prepared
by simply diluting the required  volume of
stock  solutions  in  OFW containing  70
ppm NaHCOs, 120 ppm CaS04 and  47
ppm CaCI2-2H2O. The salts were included
to simulate inorganic levels found in a
typical drinking water.

Preparation of Resins and
Graphitized Carbon Black
(GCB)
  The XAD-8 resin was air-dried and
sieved through  20- and 50-mesh size
sieves, sequentially. The 20-50 mesh size
fraction was washed and then stored in
0.1 N NaOH for 24 hours. The remaining
fines  were removed by decanting. The
resin was soxhlet - extracted for 24 hours
each with acetone, hexane and methylene
chloride. The cleaned resin was stored in
methanol. In the laboratory-scale experi-
ments, glass columns (200 x 13 mm I.D.)
with Teflon stopcock were packed with 15
mL bed volumes (B.V.) of XAD-8. In order
to process 100  L of test solution, larger
glass  columns (500 x 34 mm I.D.) with
250 mL B.V. of XAD-8 were  prepared.
Immediately before passage of the test
solution, the resin  bed  was rinsed with
0.1N NaOH, 0.1NHCI and OFW in order to
eliminate  methanol  and stabilize the
column. The samples were processed at a
flow rate of approximately 15 B.V./hour.
  AG  MP-50 (20-50 mesh, H+-form) was
purified by Soxhlet-extraction  with
methanol  (24 hrs)  and stored  in fresh
solvent. Glass column dimensions  were
the same as for  the XAD-8 resins in both
the laboratory-scale and 100-liter  pilot-
scale  experiments.  Just prior to use, the
AG MP-50  resin  was  rinsed with  3N
NH4OH, until breakthrough of ammonia
was observed, followed by four B.V. of 2N
HC1,  and finaHy  with OFW until the
effluent was Cl~ free.
  GCB was washed with acetone, methy-
lene chloride, and  OFW prior to column
packing.  Since  this material is  fragile,
care was taken  to avoid any mechanical
stress which might  cause particle rupture
and consequently generate  flow-rate
problems. In the laboratory-scale experi-
ments, 200 mg  of GCB were packed in a
glass  column (200 x 5  mm I.D.) with a
Teflon  stopcock.  In the  large scale
experiments, 10 g of GCB were packed in
a glass column  (300 x 35 mm I.D.) fitted
with a Teflon rotaflo valve.

Isolation Scheme
  The flow  schematic  of the isolation
scheme devised and evaluated in the
bench-scale phase  of the study is shown
in Figure  1. The test solution was first
acidified to pH 2 and passed through the
XAD-8 column by gravity flow at a rate of
approximately  15  B.V.  hr~1. The final
portion of test  solution was  displaced
from the  resin with 1 B.V. of 0.01 N HCI
rinse and  combined with the  initial
column effluent. Next, the hydrophobic
acid fraction was desorbed with 0.25 B.V.
of 0.1N NaOH followed by 1.5  B.V. of
OFW.
  Following elution of the hydrophobic
acid  fraction, the XAD-8 effluent plus
rinse was adjusted  to  pH  10 with 1N
NaOH. This solution was then recycled
through the XAD-8 column at a rate of
approximately 15  B.V. hr~1 followed by
2.5 B.V.  of OFW  which was  combined
with  the test solution effluent. The
hydrophobic base fraction was eluted
with 0.25 B.V. of 0.1 N HCIfollowedby 1.5
B.V.  of 0.01N  HCI.  The  hydrophobic
neutral fraction was recovered by transfer-
ring the XAD-8 resin from the column to a
separatory  funnel and  extracting with
three 50 mL aliquots of methylene
chloride.
  The test solution  effluent,  which
should now contain  only  hydrophilic
substances, was readjusted to  pH 2 with
1N HCI and passed through the AG MP-
50 cation exchange column at a flow rate
of approximately 15 B.V. hr~V Desorption
and  elution of the  hydrophilic base
fraction  was  accomplished  with  1N
NH4OH. Finally, the test solution effluent
containing  primarily hydrophilic acids
and  neutrals, was adjusted to  pH 7 and
passed through the graphitized  carbon
black column  at a rate which allowed a
0.5-minute  contact time. Elution of the
adsorbed hydrophilic solutes was accom-
plished with methylene chloride.
  In  the  pilot-scale  experiments, two
XAD-8 columns, one for each pH condition
were used,  rather than recycling  the pH-
adjusted effluent through the same
column. Extraction of the hydrophobic
neutral fraction from XAD-8 was accom-
plished by shaking the resin with methylene
chloride in the glass column.
Results and Discussion

Bench-Scale Studies
  The original scheme proposed for the
trace enrichment of  model organic
solutes consisted of Amberlite  XAD-8
resin, AG MP-50 cation  exchange resin
and Duolite A-7 anion exchange resin in
series followed  by  reverse  osmosis.
However,  initial testing indicated that
Duolite A-7, as utilized in this system, did
not significantly increase model solute
recovery and it was eliminated from
further  study.  Reverse osmosis was
shown to recover a substantial amount of
hydrophobic neutrals.
  Table 1 shows the average recoveries
obtained from six  repetitive experiments

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            Water Solution pH 2
         1
I-
                 XAD-8
                                 (2) Elution with NaOH
                                 (4) Elution with HCI
                                 (5)  Extraction with CH^CL^
             (3)

   Water Solution pH 10

  	J
                                       ^>   Hydrophobic Acids

                                       ^»   Hydrophilic Bases

                                      -^  Hydrophobic
                                             Neutralis
                   Water Solution pH 2
               AC MP-50
                                 (71  Elution with NH
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hydrophobic neutral fraction was presumed
lost by the volatilization associated with
the concentration and analytical proce-
dures.
  Because numerous model soluted
were only partially adsorbed on XAD-8
and AG MP-50, adsorption studies were
also conducted with  graphitized carbon
black (GCB).  Recovery data for this
adsorbent are provided in Table 2.

Pilot-Scale Studies
  The average  recoveries  of the model
compounds from  five 100-L batches of
test solution are shown  in Table 3. The
majority of the model compounds demon-
strated lower  recoveries  than those
observed in the bench-scale experiments.
Part of the failure was attributed to humic
acid breakthrough on the XAD-8 column
at pH  2. This breakthrough of humic acid
resulted in the formation of solid calcium-
humate upon adjustment  of the effluent
to pH  10.  This affected column flow
characteristics and  may have caused
some coprecipitation  of other  model
solutes.
  Incomplete humic acid adsorption was
attributed to insufficient quantities of
XAD-8. The decision to utilize a resin bed
Table 2.   Recovery of Model Compounds on Graphitized Carbon Black
Compound
2,4-Dichlorophenol
Quinoline
Isophorone
1 -Chlorododecane
2,4'-Dichlorobiphenyl
2,2',5,5'-Tetrachlorobiphenyl
Anthraquinone
bis-(2-Ethylhexyl)phthalate
Phenanthrene
Caffeine
Furfural
MIBK
Desorbed from GCB
115.2
97.5
16.3
51.2
48.6
54.1
92.1
51.1
114.0
92.1
NF
6.7
Extracted from
water after GCB
NF
NF
92.4
NF
0.9
37
NF
64.3
NF
NF
26.0
65.5
NF = Not found
volume of 250 ml, in the pilot study, was
based on the  following factors: known
capacity  of  XAD-8 for aquatic humic
material, the requirement of a 50-fold or
greater concentration of  solutes and a
desire to minimize resin artifacts. Unfortu-
nately, the  capacity of XAD-8 resin for
commercially available humic acid (soil
origin) differed appreciably from the
reported values for aquatic humic material.
  The low recovery of 2,6-di-tert-butyl-4-
methylphenol  was attributed to partial
oxidation, since 2,5-bis-cyclohexadiene,1,4-
dione-bis(1,1 -dimethyethyl) was tentative-
ly identified in the test solution and  in the
hydrophobic  neutral  fraction.  Further
evidence was obtained from the observed
continuous decrease of this compound in
the organic standard solution used for GC
analysis. Glycine was also found  in
considerably  lower  amounts in the
hydrophilic base fraction, since the
amount of Ca++ ions present in 100 L of
test solution  exceeded  the exchange
capacity volume of the AG MP-50 resin
(1.7 meq/mL).

Conclusions
   1. A method for the isolation and con-
     centration of 22 model  organic
     compounds from water (Table 1)
     was developed. The process separ-
     ates the organic solutes into several
     fractions  based  on  adsorption on
 Table 3.   Average Recovery of Model Compounds From Pilot-Scale Study
                                                                       % Recovery (S.D.)


Compound
Stearic Acid
Trimesic Acid
2,4-Dichlorophenol
Quinaldic Acid
Isophorone
Biphenyl
1 -Chlorododecane
2,6-di-tert-Butyl
4-Methylphenol
2-4'-Dichlorobiphenyl
2,2', 5,5'- Tetrachlorobiphenyl
Anthraquinone
Phenanthrene
bis(2-Ethylhexyl)
phthalate
Glucose""
Furfural
Quinoline
5-Chlorouracil
Caffeine
Glycine
Humic Acids
Chloroform
MIBK
ND - Not Detected
NA = Not Analyzed

Hydrophobic Acid Hydrophobic Base
Fraction (XAD-8) Fraction (XAD-8)
7.819.1)
47.6(19.8)
11.3(11.3)
ND ND









2.0 (1.9)



61.6(25.6)



34.0(4.6)





Hydrophobic Neutral
Fraction (XAD-8)




37.4 ( 3.4)
568(14.4)
94.7 ( 3.5)
8.4(12.6)

70.1 (10.3)
64.8(14.7)
59.9 (13.8)
38.6 (6.9)
60.9(178)


ND





ND
3.3 (27)


Hydrophobic
Base Fraction GCB
(AG MP-50) Fraction




3.9 (7.3)











ND

27.8(10.7)
43.2 (28.4)
4.8(1.9)






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     Amberlite XAD-8 resin, AG-MP-50
     cation  exchange,  and  graphitized
     carbon  black under  varying  pH
     conditions.  Out of the  22 model
     compounds evaluated, the following
     fifteen compounds showed average
     recoveries between 30% and 90%:
     stearic acid; trimesic acid; isophor-
     one; biphenyl; 1-chlorododecane;
     quincline;  2,4'-dichlorobiphenyl;
     2,6-di-tert-butyl-4-methylphenol;
     2,2',5,5'tetrachlorobiphenyl; anthra-
     quinone; phenanthrene; bis-(2-
     ethylhexyOphthalate; caffeine; humic
     acid; and glycine.
  2. The fractionation system in general
     gave unsatisfactory recovery results
     for the  more polar, water soluble
     and/or volatile solutes 5-chloroura-
     cil, glucose, quinaldic acid, furfural,
     chloroform, and methyl isobutylke-
     tone. The  lone exceptions  were
     glycine and  trimesic acid which
     were recovered  on  the cation
     exchange resin (AG MP-50) and
     XAD-8 resin,  respectively.
  3. The majority of the  compounds
     displayed a 15% or greater decline
     in  adsorption in the  pilot-scale
     study, as compared to  the bench-
     scale experiment. This  difference
     presumably resulted from undersized
     resin beds.
  4. The adsorption of the model solutes
     was found  to be unaffected by the
     presence of humic acid.
  5. The introduction of artifacts by the
     resins appeared to be within reason-
     able limits  (only three  impurities
     were detected at levels comparable
     to that of the  model compounds).
  6. The presence of a  2  ppm free
     chlorine  residual  carried through
     the adsorption scheme did not
     produce  any  major GC detectable
     artifacts.

Recommendations
  1. To improve  mass balance determin-
     ations,  future evaluation studies
     should include the use of radiolabeled
     model compounds where possible.
  2. Aquatic humic acid, isolated from a
     major drinking water source, should
     be  substituted  for commercially
     available humic  acid  in future
     method evaluations, despite the
     increased cost.
  3. Both resin capacity (batch studies)
     and column  breakthrough  data
     should be used to establish column
     dimensions for processing  large
     volumes of test solutions. Where an
     increased concentration  factor  is
     necessary, the use of multiple
column concentrations should be
evaluated since solute breakthrough
is a function of the column distribu-
tion coefficient as  well  as  resin
capacity.
To provide increased recovery of a
broader spectrum of organic com-
pounds, resin columns should be
used in combination with reverse
osmosis.
                                                                      U. S. GOVERNMENT PRINTING OFFICE: 1985/559-111/10764

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    E. S. Chian.  J. H. Reuter. and M.  F. Giabbai are with Georgia Institute of
      Technology, Atlanta, GA 30332.
    H. P. Ringhand is the EPA Project Officer fsee below).
    The complete report, entitled "Isolation and Concentration of Organic Substances
      from Water—Using Synthetic Resins and Graphitized Carbon Black," (Order No,
      PB 85-125 672; Cost: $13.00, 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:
            Health Effects 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
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