United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-85/108 Dec. 1985
Project Summary
Destruction of PCBs—
Environmental Applications of
Alkali Metal Polyethylene
Glycolate Complexes
Frank J. laconianni
This project is a follow-up on a study
which focused primarily on the feasib-
ility of chemical detoxification of PCB-
contaminated soil using Franklin Re-
search Center's (FRC's NaPEG) Rea-
gents. The research described in the full
report involves primarily a laboratory
study of Sodium Polyethylene Glycol,
the most effective NaPEG Reagent in
terms of reactivity and stability. The
study was aimed at identifying treat-
ment conditions necessary for the most
efficient decontamination in field appli-
cations. On-site and off-site field veri-
fication studies were also conducted
using PCB-contaminated soil from spills
in Buffalo, NY and Philadelphia. PA.
I n the first phase of this study, experi-
ments using soils contaminated in the
laboratory were presumed to demon-
strate that the concentration of PCBs in
soil can be reduced to below 50 ppm by
direct addition of the NaPEG reagent
under ambient conditions typical of an
in-situ treatment of a spill.
Laboratory tests conducted during the
second phase of this project centered
mainly on the treatment of PCB-con-
taminated soil obtained from the two
spill sites mentioned above. The effects
of variable reaction parameters which
affect the rate of decontamination were
examined in detail.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The accumulation of polychlorinated
biphenyls (PCBs) and polychlorinated
dibenzodioxinsfPCDDs, "dioxins")insoil,
sand, and living tissue is a serious
problem. Although a great amount of
work has been done in the area of direct
chemical decomposition of these and
other halogenated organics, relatively
little effort has been directed toward in
situ chemical detoxification.
The "cleanup" of a contaminated site
usually involves landfilling and is not
really a permanent detoxification but
rather a transfer of a toxic spill from one
location to another. Landfilled toxic ma-
terials are still in the environment and
will persist there until they are chemically
destroyed.
In the chemistry laboratory at the
Franklin Research Center (FRC) during
the summer of 1978, a chemical reagent
was synthesized for use to dechlorinate
PCB oils. Since that time a series of
reagents have been developed and are
now called MaPEGtm* Reagents. They are
essentially alkali metal polyethylene gly-
colates which produce rapid dehalogena-
tion of halo-organic compounds of all
types—in open air systems.
The aerobic nature of the NaPEG
System immediately suggested its poten-
"Mention of trademarks or commercial products does
not constitute endorsement or recommendation for
use by the U S. Environmental Protection Agency.
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tial for use on hazardous chemical spills.
In August 1 979, the U.S. Environmental
Protection Agency (EPA) provided grant
support to FRC to investigate the chem-
istry underlying the dehalogenation pro-
cess, concentrating on dechlorination of
PCBs. Subsequent EPA grant assistance
was provided for a limited field study of
the effects of a NaPEG reagent on PCB-
contammated soil. This research was
described in a Project Summary entitled
"Dehalogenation of PCBs Using New
Reagents Prepared from Sodium Polyeth-
ylene Glycolate—Application to PCB
Spills and Decontaminated Soils," August
1982.
Additional EPA grant assistance was
awarded in 1982 for the detailed investi-
gation of the effects of variable reaction
parameters on the rate and extent of
chemical decontamination of the sub-
strate. This research focussed almost
exclusively on the direct chemical treat-
ment of PCB-contaminated soil. The
continued laboratory investigation was
aimed at identifying treatment conditions
necessary for the most efficient decon-
tamination in a direct field application.
During the study an optimum reagent
composition was selected based on chem-
ical considerations. Maximum reactivity
toward PCBs and other halogenated
organics coupled with minimum sensi-
tivity to reagent-deactivating side reac-
tions was sought in selecting the best
reagent formulation for further study. The
full report describes the research per-
formed and the results obtained.
Early Experiments Using
Laboratory-Contaminated Soils
Laboratory experiments using simu-
lated soil substrates spiked with PCBs
confirmedthat PCBs aredechlorinated by
the NaPEG Reagents under mild, ambient
conditions. Subsequent experiments us-
ing actual soils spiked with PCBs clearly
show, however, that water in soil greatly
reduces the rate of dechlorination and the
effectiveness of the reagents on PCBs in
real soils These adverse effects were
greater than expected from the prelim-
inary results obtained in previous studies.
In addition, it was found that the most
effective reagent formulation for the
dechlorination of PCBs in controlled one-
phase reactions and model substrates
was not the most effective reagent for
PCBs in soil, specifically because of its
extreme sensitivity to water. The reagents
described in the full report are much less
sensitive to deactivation with water.
The next phase of experiments show
that soil freshly contaminated with 1000
ppm of Aroclor 1260 can be decontam-
inated to below 50 ppm PCBs in only a
few days with a direct application of
Potassium Polyethylene Glycol (KPEG)
350-1. Particularly encouraging is the
fact that this reagent can be used on soil
containing some water and organics, and
that it continues to react after several
days in open air
On-Site Treatment of
PCB-Contaminated Soil
The first completed on-site experiment
in the application of reagent to contam-
inated soil was carried out by FRC per-
sonnel in Buffalo, NY, in August 1983.
This experiment produced inconclusive
results in contrast to those obtained under
laboratory-controlled conditions.
The only known major problem which
has adversely affected the results of this
initial field study involves the inhibiting
effect of water on the chemical degrada-
tion rate. Subsequent laboratory tests
demonstrated simple techniques that may
be used to minimize the adverse effects of
water on the rate of decontamination.
The results of more recent, systematic
laboratory investigations are much more
encouraging than the preliminary on-site
test. The level of PCBs in contaminated
soil can be reduced from approximately
1000 ppm (highly contaminated) to below
50 ppm by direct chemical treatment
under relatively mild conditions. This
suggests that the direct on-site chemical
treatment of PCB-contaminated soil is a
promising process.
Results using PCB-contaminated soil
from the Philadelphia, PA, site showed
that significant dechlorination is achieved
by simply air drying the soil at room
temperature prior to the application of the
reagent. Without this pretreatment, in-
significant decontamination was ob-
served for the relatively wet soil, even
when KPEG350-1 was used.
When the soil sample was obtained
from the site in May 1984, it was noticed
that the treated soil was still very wet.
Also, water condensation was observed
under the plastic sheet that covered the
plot. The sheet may keep the rain out, but
it also tends to keep moisture in. This was
probably not a major disadvantage, how-
ever, because without the cover, all but
the soil particles closest to the surface
would retain most of their excess mois-
ture, even in extremely dry atmosphere.
In light of this, thorough mixing of the soil
in air, prior to reagent application, should
be an essential minimum pretreatment.
Excess water, if not adsorbed, can be
easily removed by exposing all of the soil
to the surface, even at ambient temper-
atures. If such a treatment is performed
on-site, especially on a warm, dry day, the
promising results obtained in the labo-
ratory tests may be verified. At this time,
the various inhibiting effects of water are
the only known major problems which
have adversely affected the results of this
initial field study. Air drying is a very
important step which should greatly
minimize these effects in field tests.
The on-site treatment of soils contam-
inated with PCBs and other halogenated
aromatics looks very promising, based on
the results obtained in the laboratory
studies. Considerable work remains to be
done in the area of process development,
particularly with respect to reducing the
inhibiting effect of water and optimizing
conditions for soil decontamination.
Various solvent pretreatment and soil
heating methods, for example, deserve
additional and scaled-up investigation.
Some of these techniques are currently
being studied in the laboratory. Field
testing must continue, however, not only
to verify laboratory results, but to provide
first-hand experience in real-world situa-
tions that is necessary for the develop-
ment of a field process.
Conclusions
The results of the overall study show
that FRC NaPEG Reagents can signif-
icantly reduce the concentration of PCBs
in contaminated soils under controlled
laboratory conditions. There are, how-
ever, several areas in which improvement
and optimization must be achieved in
order to develop a viable and economical
process for chemically treating PCB-con-
taminated soils in the field. The most
recent results of laboratory experiments
suggest that:
• Application of reagent to wet soil is not
as effective in reducing the concentra-
tion of PCBs. The water present in a
typical reaction sample greatly dilutes
the reagent. Air drying of the soil is
necessary prior to treatment.
• Increased temperature is, as expected,
more effective in reducing PCB con-
centration in soils.
• Increasedtemperaturealsoeases mix-
ing of reagent and soil; this should aid
the continued reduction of PCB in soil
over a period of time.
• An increase in reaction time shows
continued decrease in the concentra-
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tion of PCBs in the soil, particularly of
the more active components
A greater reagent to soil ratio has
shown the best results. This is likely
due in part to increased contact of
reagent with PCBs This effect can
perhaps be duplicated by a better
method of mixing. In addition, in-
creased reagent to soil ratio means
less soil water contamination in the
reagent. This should also increase the
rate of dechlorination.
The syringe application method, which
minimizes the amount of atmospheric
water coming in contact with the
reagent, is sufficient; no additional
advantage is realized by applying the
reagent to the soil under nitrogen.
Kerosene added to the soil as a solvent
pretreatment is more effective in real-
izing dechlorination than toluene, or
no solvent at low reaction tempera-
tures, but not significantly more effec-
tive than no solvent pretreatment,
when reactions are conducted at
higher temperatures.
The reagent diluted with kerosene or
toluene prior to application to the soil
is not as effective in dechlorinating the
PCBs as the reagent alone applied to
the soil.
Frank J. laconianni is with Franklin Research Center, Philadelphia, PA 19103.
Charles J. Rogers is the EPA Project Officer (see below).
The complete report, entitled "Destruction of PCBs—Environmental Applications
of Alkali Metal Polyethylene Glycolate Complexes," (Order No. PB 86-105
293/AS; Cost: $11.95, 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:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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EPA/600/S2-85/108
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