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AR226-2648
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AR226-2648
TECHNICAL REPORT
IN-SITU TREATMENT OF SURFACTANT-CONTAMINATED AQUIFER BY ELECTROCHEMICAL PROCESSES
submited to
Du Pont Company
and
Delaware State Research Partnership
March, 1994
by 0
C. P. Huang (Principal Investigator) Chieh-Sheng Chu (Graduate Research Assistant) Luis R. Taldyama (Graduate Research Assistant)
^r^^4-I^SS
S ^ 'X.i^^
EID103181
Table of Contents
List of Figures......................................................................................................... iii List of Tables ................................................................................................................... ix
LSummary.......................................^........,.......................,...............................................x
IntrodLuIc.tiSotna:t.e..m...e.n..t..o..f.--th.e...p..r.o..b..l.e..m...a..n..d--s..i.g..n--ifi.c..a..n..c--e.o..f.--th.e...r.e..s..e.a..r.c.--h .p--ro..j.e..c.t..:............--....--.....1I
L2. Theoretical background:............................................................................... 1 1.2.1. Electro-osmosis: ..,--.................--.--......----..--.........----... 1
n. Experimental Procedures:.................................._....................................................4
ILL Analysis of die site groundwater quality:_................................................ 4^; y,;;
n.2.
IILLl1. l..2A. lCl oanudmutcyt:i.v.i.t.y. .:...............................................................................................................................................................54
uai,"',
-<, -w
n.1.3. Total dissolved solids:.................................................................. 5
n.1.4. Analysis of the major cations:..................----...,,....----......... 6
n.1.5. Analysis of the minor cations:...................................................... 7
ILL6. Determination of carbonates:....._..............................................7
IL1.7. Analysis ofchlodde:.................................................................... 8
n.1.8. Analysis of sulfate:...................................................................... 8
n.1.9. Analysis of nitrate:.......................................................................9
n.1.10. C8 analysis in the liquid phase:.................................................. 10
Characterization of the son'samples:7r....7.^.7..7.:.:.::.:.::.;.......;.:..7...:;.:.....;. 11
-
n.2.1. Composition analysis:.................................................................. 11
nn..22..23..SSooUipl Hor:g..a..n..i.c..m...a..t.t.e..r.:............................................................................................................................................1l32 n.2.4. Soil effective cation exchange capacity:...................................... 13 EL2.5. Moisture content:.......................................................................... 14 n.2.6. Specific surface area:.................................................................... 15
^ nIL.22..78..pHHyZdPrCau:.l.i.c...p..e..r.m...e..a.b..i.l.i.t.y..:.......--......................................................................................................--.............1166
n.2.9. C8 analysis in the soa:......-.......................--.............................. 17
EL3. Adsorpdon/desorpdoa experiments:............--.--........----............--....... 19
n.3.1. Soil sample preparation:.........--.---- --.----.----..........----... 19
n.3.2. Batch adsorption experiments:...........................----.----.--.....20
n.3.3. Batch desorption experiments: .........--........--..................--21
IL3.4. Adsorption study under the electrical field:.......----...--.....----..21
IL3.5. Analytical methods:...----.........--...--.........--........ --....--.,, 22
IL4. Electro-osmosis tests:..._.....................................----..........--.............--. 22
IL4.1. Soil sample preparation: .......,,.........................--.--...._--_--.22
DL4.2. Electro-osmosis apparatus set up and testing:.......................--.. 23
IL43. Electro-osmosis experiments with pH control:.--...................-- 24
n.4.4. Moisture content effect on the electro-osmotic flow;.....--..._... 24
IL4.5. Analytical methods:...--.....--..----........----....................--.. 25
in. Resuinlt.sl.anACdhnaaDrliyasscctiusesrosizifoattnhisoe:ns..io.t.e.f..tg.h.r.eo..u.s..no..di.l.w..a..t.e..r..q..u..--ali.t.y--: ...,,.....--..............................,,........--.......--....--.....................222766
in.2. IIL2.1. Composition analyssaism: ples:..................................----.............. 27
DL2.2. Soil ptL-
----.....--.----.........----..--.............. 27
.n..i.c..m...a..t.t.e..r.:...............................,,.......-.............----........ 27
ffl
DniI..22..43.. SSooiill eofrfgeactive cation--ex.c..h..a--n,,g.e--c.a.p..a..c.--ity--:...............,......................,,................................. 28 2
in.2.5. Moisture content:.......--....--.....----.......--......................... 28
M.2.6. Specific surface area:................................--..........----........-- 28
8
EID103182
ni.2.7. pHzpc:......................................................................................... 29 DI.2.8. Hydraulic permeability measurements:.................................... 29 ffl.2.9. C8 analysis:................................................................................ 30 DI.3. Adsorption/desorption experiments:..............................................--......... 32 ffl.3.1. The effect of pH on C8 adsorption/desorption:.......................... 32 ffl.3.2 Effect of soil/water ratio:............................................................. 33 IIL3.3 Temperature effect on the C8 adsorption/desorpdon:.................. 34 DI.3.4 Initial C8 concentration:.......-....................................................... 34 ni.3.5. Adsorption under electrical field; ...............................................35 in.4. Electro-osmosis tests:.................................................................................36 ni.4.1. Electro-osmotic water flow:........................................................ 36 in.4.2. Coefficient of electro-osmotic permeability (ke):....................... 38 m.4.3. Current density:........................................................................... 38 IH.4.4. Influent pH:................................................................................. 38 ffl.4.5. Effluent pH:................................................................................. 39 m.4.6. C8 concentration at the effluent:................................................. 39 ffl.4.7. C8 concentration at the influent:................................................. 39 DI.4.8. C8 removal:................................................................................. 40 in.4.9. Water content:............................................................................. 41 m.4.10. The pH profile:.......................................................................... 41 IIL4.11.C8 distribution:.........................................................................41 DI.4.12. Mass balance: ............................................................................43 in.4.13. Moisture content effect on electro-osmotic flow:.................... 43 IV. Conclusions and Recommendations......................................................................... 44 V. References ............................,.................,,.........--......................................................47
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EID103183
List of Figures
Figure 1.
Constant head penneameter.
Hydraulic head, h = 44 cm; Soil sample length, L = 11 cm;
Cross sectional area, A == 19.6 cm2.
Figure 2a. Adsorption system type A for the adsorption study under no electrical field. Figure 2b. Adsorption system type B for the adsorption study under electrical field.
Figure 2c. Adsorption system type C for the adsorption study under electrical field.
Figure 3. Figure 4. Figure 5.
Typical electro-osmosis apparatus.
Electro-osmosis apparatus for tests under controlled pH conditions.
Characterization of the site groundwater. Major cations.
Figure 6
Characterization of the site groundwater. Minor cations.
Figure 7. Characterization of the site groundwater.
Anions.
, ^.^
Figure 8. Ionic distribution of the site groundwater.
Figure 9a. Characterization of the soil samples. Soil composition analysis of ADPS-1 soil samples (stack bars).
Figure 9b. Characterization of the soil samples. Soil composition analysis of ADPS-l soil samples.
FigurelOa. Characterization of the soil samples. Soil composition analysis of ADPS-2 soil samples (stack bars).
Figure lOb. Characterization of the soil samples. Soil composition analysis of ADPS-2 soil samples.
Figure 1L Characterization of the soil samples. Soil pH of ADPS-l soil samples.
Figure 12. Characterization of the soil samples. Soil pH of ADPS-2 soil samples.
Figure 13. Characterization of the soil samples. Organic matter percentage of ADPS-l soil samples.
Figure 14. Characterization of the soil samples. Organic matter percentage of ADPS-2 soil samples.
Figure 15a. Characterization of the soil samples. Effective cation exchange capacity of ADPS-l soil samples. ^
Figure 15b. Characterization of the soil samples.
2
Exchangeable ions of ADPS-l soil samples (stack bars).
^
Figure I6a. Characterization of the soil samples.
o\
Effective cation exchange capacity of ADPS-2 soil samples.
M
m
EID103184
Figurel6b. Characterization of the soil samples. Exchangeable ions ofADPS-2 soil samples (stack bars).
Figure 17. Characterization of the soil samples. Moisture content of ADPS-1 soil samples.
Figure 18. Characterization of the soil samples. Moisture content of ADPS-2 soil samples.
Figure
19.
Characterization of the soil samples. BET plot of ADPS-2 soil sample (depth range of 0
to 5
feet).
Figure 20.
Characterization of the soil samples.
BET plot of ADPS-2 soil sample (depth range of 5
to
10 feet).
Figure
21.
Characterization of the soil samples.
BET plot of ADPS-2 soil sample (depth range of
10
to
15 feet).
Figure 22.
Characterization of the soil samples. BET plot of ADPS-2 soil sample (depth
range
of
15
to
20
feet).
Figure 23.
Characterization of the soil samples. BET plot of ADPS-2 soil sample (depth range of 20 to 25 feet).
Figure 24.
Characterization of the soil samples. BET plot of ADPS-2 soU.sample (depthjange of 25
to 30 feet).
Figure 25. Characterization of the soil samples, The pHzpc of ADPS-2 soil samples.
.s.,p-s
Figure 26.
Characterization of the soil samples. Determination of the pHzpc of ADPS-2
soil
sample
(depth range. s^QSto5
;T"
feet).
Figure 27.
Characterization of the soil samples. Determination of the pHzrc of ADPS-2
soil sample (depthrange of 5
to
10
feet).
Figure 28.
Characterization of the soil samples. Determination of the pHzpc of ADPS-2
soil
sample
(depth range ,oyf,..1.0,,.to
15
feet).
Figure 29.
Characterization of the soil samples. . Determination of tile pHzpc of ADPS-2 soil sample (depthrange of
15 to 20
feet).
Figure 30.
Characterization of the soil samples. Determination of die pHzpc of ADPS-2
soil
sample
(depthrange
of
20
to
25
feet).
Figure 31.
Characterization of die soil samples. Determination of the pHzpc of ADPS-2
soil
sample
(depth range
of
25
to 30
feet).
Figure 32. Soil permeabilitymeasurement by constant head permeameter. Soil sample: ADSP2 (0'-5*).
Figure 33. Soil permeabilitymeasurement by constant head permeameter.
E
2 0
Soil sample: ADSP2 (5'-10').
k--
0
Figure 34.
Soil
permeabilitymeasurement
by
constant
head
permeameter.
Soil sample: ADSP2 (15'-20').
IV
EID103185
Figure 35. Soil permeability measurement by constant head permeameter. Soil sample: ADSP2 (20'-25').
Figure 36. Soil permeability measurement by constant head permeameter. Soil sample: ADSP1 (23'-25').
Figure 37. Hydraulic permeability profile for ADPS-2.
Figure 38. C8 concentration profile at ADPS-1 site.
Figure 39. C8 concentration profile at ADPS-2 site.
Figure 40.
Residual C8 concentration as a function of pH. Soil sample: ADPS2 (0'-51). Experimental conditions: initial C8 concentration = soil/water ratio = 0.05 g/mL; ionic strength = 0.1 M
50 mg/L; NaC104.
Figure 41.
Residual C8 concentration as a function of pH. Soil sample: ADPS2 (5'-10'). Experimental conditions are the same as in Figure 40.
Figure 42.
Residual C8 concentration as a function of pH. Soil sample: ADPS2 (10'-15'). Experimental conditions are the same as in Figure 40.
Figure 43.
Residual C8 concentration as a function of pH. Soil sample: ADPS2 (15'-20'). Experimental conditions are the same as in Figure 40.
Figure 44.
Residual C8 concentration as a function of pH. Soil sample: ADPS2 (20'-25'). Experimental conditions are the same as in Figure 40.
Figure 45. Figure 46.
Residual C8 concentration as a function of pH. Soil sample: ADPS2 (25'-30').. Experimental conditions are the same as in Figure 40.
Percentage of C8 adsorbed as a function of pH. Son sample: ADPS2 (0'-51). Experimental conditions: initial C8 concentration = 50 mg/L; soil/water ratio = 0.05 g/mL; ionic strength = 0.1 M NaC104.
Figure 47.
Percentage of C8 adsorbed as a function of^H. Soil sample: ADPS2 (5'-10'). Experimental conditions are the same as in Figure 46.
Figure 48.
Percentage of C8 adsorbed as a function of pH. Soil sample: ADPS2 (10'-15'). Experimental conditions are the same as in Figure 46.
Figure 49.
Percentage of C8 adsorbed as a function of pH. SoH sample: ADPS2 (15'-20').
Experimental conditions are the same as in Figure 46.
Figure 50.
Percentage of C8 adsorbed as a function of pH. Soil sample: ADPS2 (20'-25'). Experimental conditions are the same as in Figure 46.
Figure 51.
Percentage of C8 adsorbed as a function of pH. SoU sample: ADPS2 (25'-30'). Experimental conditions are the same as in Figure 46.
w
AMJiUA,.
ill sw-tpie -aiidaati--.
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EID103186
Figure 52. Equilbrimn diagram ofC8 species.
Figure 53. Fraction of surface soil protonatedspeciesvs. pH.
3
Figuie54a. Amount of C8 desorbed vs. pH.
Experimental conditions: soil sample = ADPS2 (0'-5');
initial C8 concentradon in solid phase =1.0 mg/g;
soil/water latio = 0.05 g/mL; ionic strength = 0.1 M NaC104.
Figure54b. Percentage of C8 desorbed vs. pH. Experimental conditions: soil sample = ADPS2 (0'-5'); initial C8 concentration in solid phase = 1.0 mg/g; soiVwater ratio = 0.05 g/mL; ionic strength = 0.1 M NaC104.
Pigure55a. Amount of C8 desorbed vs. pH. Experimental conditions: soil sample =
ADPS2 (5*-10*);
initial C8 concentradon in solid phase = 1.0 mg/g;
soil/water ratio = 0.05 g/mL; ionic strength = 0.1 M NaC104.
Figure55b. Figure 56.
Percentage of C8 desorbed vs. pH.
Experimental conditions: soil sample == ADPS2 (5'-10');
initial C8 concentration in solid phase = 1.0 mg/g;
soiVwater ratio = 0.05 g/mL; ionic strength = 0.1 M NaC104.
Soil water ratio effect on the C8 adsorption for six soil samples
fiom the ADPS2 site Experimental conditions: initial C8 concentration =
50 mg/L; pH
ionic strength = 0.1 M NaC104.
=7.0;
Figure 57. Soil water ratio effect on theC8 adsorption. soU sample: ADPS2 (0'-5'). . Experimental conditions: initial C8 concentration = ionic strengths 0.1 M NaC104.
50 mg/L;
>wm.
,^%''? . ....,,.,,
"^',, c^w" "W-" w
Figure 58. Percentage of C8 adsorbed as a function ofpH.
Soil sample; ADPS2 (0'-5'). Experimental conditions: initial C8 concentration =
50 mg/L;
Temperature = 10 C; ionic strength = 0.1 M NaC104.
Figure 59. Percentage of C8 adsorbed as a function of pH.
Soil sample: ADPS2 (0'-5'). Experimental conditions: initial C8 concentration =
50 mg/L;
Temperature = 25 C; ionic strength = 0.1 M NaC104.
Figure 60. Percentage of C8 adsorbed as a function of pH.
Soil sample: ADPS2 (0'-5'). Experimental conditions: initial C8 concentration =
50 mg/L;
Temperature = 45C; ionic strength = 0.1 M NaC104.
^ Figure 61. Temperature effect on me C8 adsorption.
Soil sample: ADPS2 (0'-5'). Experimental conditions: initial
C8
concentration
s=
50
mg/L;
B
ionic strength =0.1M NaC104.
o
S
Figure 62. Temperature effect on the C8 adsorption.
8
Soil sample: ADPS2 (0'-5').
u<
Experimental conditions: initial C8 concentration = 50 ppm.
ionic strength = 0.1 M NaC104.
VI
EID103187
Figure 63. Temperature effect on the C8 desorption. Soa sample: ADPS2 (0'-5'). Expedmental conditions: initial C8.concentration =
ionic strength = 0.1 M Naa04.
50 ppm.
Figure 64. Residual C8 concentration as a function Of pH at initial C8 concentrations lower than 50 ppm; soil sample: ADPS-2(0'-5'). Experimental conditions: ionic strength = 0.1 M
NaC104.
Figure 65. Residual C8 concentration as a function of pH at initial C8 concentrations of 50-200 ppm;
soil sample: ADPS-2(0'-5'). Experimental conditions: ionic strength = 0.1 M
NaC104.
Figure 66. Percentage of C8 adsorbed as a function of pH at initial C8 concentrations lower than 50 ppm. Soil sample: ADPS2 (0'-5').
Experimental conditions: pH =7.0; ionic strength =
0.1 M
NaC104.
Figure 67. Percentage ofC8 adsorbed as a function of pH at initial C8 concentations of 50-200 ppm. Soil sample: ADPS2 (0'-5'). Experimental conditions: pH = 7.0; ionic strength =
0.1 M
NaC104.
Figure 68.
Partition coefficient of C8 vs. pH for initial C8 concentrations lower than 50 ppm. soil sample: ADPS-2 (0'-5'). Experimental conditions: soil/water ratio = 0.05 g/mL;
ionic strengths 0.1 M NaC104.
TOOOO* r %r?
no,;
sr&r, ^<
^(0 < . Mjiityw." v,
n
Figure 69. Partition coefficient ofC8 vs. pH for initial C8 concentrations of 50-200 ppm;
soil sample: ADPS-2 (0'-5'). Experimental conditions: Soil/water ratio = 0.05 mg/L; ionic strength = 0.1 M NaC104.
u ^. t.--mB>-
Figure 70. Adsorption experiments under electrical field.
The pH of effluent as a function of time. Experimental conditions: initial C8 concentration = ionic strength = 0.1 M, weight of soil = 200 g.
50 "mg/L,
"'1
Figure 71. Adsorption experiments under electrical field.
Amount of C8 retained in the soil as a function of time.
Experimental conditions are the same as in Figure 70.
Figure 72. Adsorption experiments under electrical field.
Cumulative effluent volume as a function of time.
Experimental conditions are the same as in Figure 70.
>
Figure 73. Electro-osmosis experiments.
S
Cumulative electro-osmotic water flow as a function of time.
S3
Piguie74a. Electro-osmosis experiments.
Coefficient of electro-osmotic permeability (ke) as a function of time for Tests
;
I,nandm.
vu
EID103188
Figure 74b. Electro-osmosis experiments. Coefficient of electro-osmotic permeability (ke) as a function of time for
Tests IV, V and VL
Figure 75. Electro-osmosis experiments.
Current density as a function of time.
Figure 76a. Electro-osmosis experiments.
The pH of influent solution as a function of time for Tests I, n and HI.
Figure 76b. Electro-osmosis experiments.
The pH of influent solution as a function of time for tests IV, V and VL
Figure 77a. Electro-osmosis experiments.
The pH of effluent solution as a function of time for Tests I, n and IB.
Figure 77b. Electro-osmosis experiments.
The pH of effluent solution as a function of time for Tests IV, V and VL
Figure 78. Figure 79.
Electro-osmosis experiments.
C8 concentration at the effluent solution as.a function of time.
Electro-osmosis experiments.
C8 concentration at the influent solution as a function of time.
Figure 80.
Electro-osmosis experiments. Cumulative C8 removed at the cathode (in milligrams) as a function of
time.
Figure 81.
Electro-osmosis experiments.
Cumulative C8 removed at the cathode (in percentage) as a function of
time.
Figure 82. Electro-osmosis experiments,
Water content distribution as a function of normalized distance from anode,
Figure 83.
Electro-osmosis experiments.
The pH across the soil sample as a function of normalized distance from
anode.
Figure 84.
Electro-osmosis experiments. Relative C8 concentration remained in the soil as a function of normalized
distance from anode.
Pigure85. The effect of moisture content on the electro-osmotic flow. Soil sample: RBLMW2 (10'-12*).
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*'" - p. >.!
s.s y
. c.rn'.?
;.,.,wi, ioie s
(;<-.
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EID103189
List of Tables
Table I. Table IL
Some experimental conditions of the electro-osmosis test conducted. Reagents used in the electro-osmosis experiments with pH control.
Table DDL Results of the characterization of the site fluid.
TableIV. Results of me characterization of the soil samples.
Table V. Mass balance of C8 for the electro-osmosis tests.
IX
EID103190
3
Summary
,j
During the project period, four major tasks were completed to study the feasibility of the removal of ammonium perfluoro-octanoate (C8) from contaminated soils. These
tasks included:
characterization of the plant production groundwater,
characterization of soil samples at the anaerobic ponds,
3
adsorption/desorptionexperiments, and
electro-osmosis tests.
Characterization of the site groundwater was the first task accomplished. A water
sample was taken from a tap on the plant site above the anaerobic ponds. The source of this
water is from on-site production wells. Properties such as pH, alkalinity, conductivity,
total dissolved solids (TDS), and concentration of major cations (Ca^, Mg^, N:a+, K-*-),
minor cations (Fe(n), Mn(H)), trace heavy metals (Pb(n), Cu(II), Cd(H), Ni(II). Zn(Di),
Co(II)), anions (HCOs-, C032-, C1-, NOa-. SC>4-), and CQz were analyzed., concentration of ammonium perfluoro-octanoate (C8) in the groundwater was also determined. The results demonstrated that Ca^*-, Na*, KCOy, C1-, and S04- are the major ionic species present in the water. C8 was detected at a concentration of about 113 ppb.
Soil samples from two locations (ADPS-1 and ADPS-2) at various depths were
received and physical-chemical properties, such as pH, specific surface area, moisture
content, organic matter, cation exchange capacity (CEC), pH at zero point of charge
(pHapc), composition, hydraulic permeability, and C8 concentration were determined. The
composition analysis showed a high percentage of clay (about 40%) in me top soil zones at
i^~
both locations (depth < 10 feet). Therefore, the shallow zone is the most suitable region
2
o
--*
where the electro-osmosis process can be effectively applied. The highestconcentrations of ^
o
C8 were also found in these shallow soil samplesin the top 10 feet; Around 5 to 16, and 5
x
EID103191
to 33 ppm of C8 were detected in the shallow soils at ADPS-1 and ADPS-2 sites, respectively. As expected, specific surface area, organic matter content, cation exchange
capacity and hydraulic permeability produced results consistent with the composition
analysis (i.e., higher percentage of clay corresponds to higher specific surface area, organic matter content, cation exchange capacity, C8 concentration, and lower hydraulic
permeability). The soil pH analysis showed that most of the subsurface soils are in the
neutral pH region (pH = 5.5 ~ 7.5) and the variation with depth is not significant. The pHzrc of the soil samples from the ADPS-2 site are in the range of 2.0 to 2.7, indicating that at higher pH values, Ihe soil particles will be negatively charged.
To examine the behavior of C8 in the soil water system, batch
adsorption/desorption experiments were conducted at various pH values, C8
concentrations, temperatures, and soil/waler ratios: "Continuous-flow-adsorption
-
experiments under an electrical field were performed to verify influence on C8 adsorption.
The results demonstrated that the C8 adsorption varies substantially with pH. Beeaus&the acidity constant of C8 is 10"2-9 and the pHzpc of the soil is in the range of 2.0 to 2.5, an
electrostatic repulsion between anionic C8 and negatively charged soil surfaces occurs at
pH values higher than 3. As a result, C8 adsorption to the soil decreases with increasing pH, and the higher the pH, the greater the amount of soil desorption.
Batch adsorption/desorption experiments were conducted at different temperatures
--wi
(0C, 25C, and 45C). The results showed that the temperature is inversely proportional
to the extent of C8 adsorption and directly proportional to the amount of C8 desorbed. C8n. w,:. soil adsorption capacity decreases with increasing temperature.
When the initial C8 concentration is below 50 ppm, the extent of soil adsorption is
^
CO
diminished significantly at pH greater than 5.0 (at least for sou/water ratio of 0.05 g/roL).
i-->
However, when the initial C8 concentration is greater than 50 ppm, the percentage of C8
o
adsorbed is higher because the hydrophobic interactions become significant to the
adsorption process.
xi
EID103192
Continuous flow apparatus were constructed to investigate the adsorption behavior under electrical fields. Three adsorption systems were adopted according to the voltage 0 applied and the positions of electrodes. They were as follows:
Type A: without voltage applied (control);
Type B: anodes placedat the influent side and cathodes located at the
effluent side;
Type C: cathode positioned at the influent side and anode at the effluent
side. 0
Three parameters (effluent pH, effluent volume and C8 concentration) were monitored to
evaluate the performance of these three reactors. The results show that type C exhibited the highest C8 retaining capacity and lowest effluent pH. Inversely, type B adsorption system produced the highest effluent pH an<Tthe lowest adsorption capacity. No differences were detected in the effluent volume between the three systems. The changes in pH of the solutions in the vicinity of electrodes were caused by the water rcdox reactions. " ' yo;-'i! <"
A total of six electro-osmosis tests under various conditions were conducted (&-"'<';r evaluate the C8 removal from the contaminated subsurface anaerobic pond soilsy^he'!T1 following Table I summarizes some of the experimental conditions of the tests, "row&'w1 < o -<'
Table I: Some experimental-conditions of the electro-osmosis tests conducted.
0
Test*
Soil
Potential
pH control
sample gradient
(V/cm)
I AD0P-5S' -2 1.0 NO
n
ADPS-2
1.5
NO
^
0-5'
in A5D-P1S0'-2 1.5 NO o0>i
"ADPS-2"
"""""""""YES""""""""""
IV 0-5'
1.5
(NaOH,pH=10)
xu
EID103193
v AD0-P5S' -f 1.5 (Ca(OHY)2E,SPH=10)
VI
mixed
1.5
' YES
soils
(CaCOa, pH=6.0)
The results demonstrated that it is practical to remove the C8 by electro-osmosis
under pH controlled conditions at influent and effluent solutions. A 97 % removal of the
C8 originally present in the soil was achieved in Test IV under pH control (pH = 10) with
NaOH/HCl. Other tests using Ca(OH)2 and CaCOs, did not yield the same results possibly
"^
due to the following reasons: a) high pH conditions caused precipitation of some salts,
e.g., CaCOs that coated the surface of the electrodes, yielding low efficiency of the electro-
osmosis process; b) By introducing calcium (instead of sodium) into the system, the ionic
strength increases substantially, causing a diminishing of the zeta potential (Q and
consequently the fluid velocity through the soil towards the cathode. Electro-osmosis
,,.
"!*-
experiments performed without pH conditioning showed little C8 removal. In these tests,at,a; p . .i'-ix
significant amount of C8 remained in the soil presumably caused by the low fluid velocity ;< s i.e sn aw sw ;.
and the build up of strong pH gradients across the soil core.
;r ^ .'eaistsis Msaw;
3
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0\
t--t
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EID103194
I. Introduction
Electro-osmosis, an electro-kinetic phenomenon, has been one of the emerging techniques for in-situ treatment of contaminated subsurface soil and groundwater. This is the same process used by geological engineers to consolidate foundations for construction.
The electro-osmosis process relies on externally voltage applied to a soil matrix system to induce water movement The cations migrate toward the cathode and the anions toward the ''" anode. Because there is an excess of solvated cations near the negatively charged soil surface, a net movement of water towards the cathode is observed. K>
The study included the following specific objectives: - Investigated the influence of various physical-chemical properties of the soil matrix on the removal process; - Evaluated the factors controlling the removal process; - Obtained parameters needed for the design of the electrokinetic process for in-situ removal.
1.2. Theoretical background:
L2.1. Electro-osmosis:
^
Electro-osmosis has found broad application in colloid characterization, particle
."&
separation and engineering construction (foundation consolidation). In an electrical field, 2
w
EID103195
water will flow from the positive end (anode) to the negative end (cathode). Casagrande (1949) has pioneered some of the first successful field application of this technique. 3
Two theories have been proposed to described the electro-osmosis water flow; the Helmholtz-Smoluchowski (1879) and the Schmid (1952). According to the HelmholtzSmoluchowski theory, the How rate of water (Qe) moving in a capillary of length, L under
electrostatic field, 0, is
(^tw> c 4wnL
where ,<&,(,, and T| are the dielectric constant, field strength, electrokinedc potential and viscosity. However, according Schmid (1952) the water flow rate is:
n^~-~A^L^~
where r, q, F are the radius, volume charge density in the pore, and Faraday constant. Apparently, the Helmholtz-Smoluchowski theory predicts a flow rate that is independent of
pore size whereas the Schmid theory predicts that the flow rate is proportional to the cross
sectional axes. of the pores. Neither theory allows for an exchange of electrolytes in the
pores beyond the number of cations needed to balance the negative charge of the clay
"">
particles. However, Esrig and Majtenyi (1965) have proposed the following equation:
1
K r2 <S>
Q e =2- l n ( l +r - ) (T|- ) p (L- )
>
S
where p, K are the average mobile surface charge density and the parameter characterizing
g
(TI
>--
the double layer. The above equation is able to accommodate both the Helmholtz-
t.
EID103196
Smoluchowsld and flie Schmid theories. Nevertheless, in field practice, the water flow rate is found to be a function of the cross-sectional area of die flow:
Qe=ke*eA where k and ie are the electro-osmotic permeability, the electrical potential gradient, and electrode surface area. Casagrande has determined the electro-osmotic permeability of various soil and found that the Kg value varies only within one order of magnitude with an average value of 5 x 10"5 cm^sec-v. Chappel and Burton (1975) reported that a flow of 5501 per day was achieved with steel electrodes at a spacing of 3 meters and applied DC voltage of 40 V.
Vif
0
EID103197
II. Experimental Procedures
11.1. Analysis of tile site groundwater quality: Alkalinity, pH and conductivity were measured immediately upon receiving the
groundwater samples in our laboratory. The addition of 50 mL concentrated HNOa to 1 gallon of water sample was used to preserve it for future chemical analysis.
Atomic absorption spectrophotometry technique was employed to determine the
concentration of all metals in the water. The major cation concentrations such as potassium, calcium, sodium, and magnesium were determined by direct aspiration into air-
acetylene flame while the minor cations and trace heavy metals were analyzed by the graphite furnace (electrothermal atomic absorption method).
Potentiometdc method using a chloride ion selective electrode was used to determine the concentration of Cl' in the process water.
A turbidimetric method was employed to determine the sulfate concentrations in the; water sample.
For the analysis of nitrate, an ultraviolet spectrophotometric method was used. Other anion concentrations such as C032- and HCOa- were calculated from the alkalinity and pH measurements. All chemical analysis (except Cl") were performed according to die Standards.; Methods for me Examination of Water and Wastewater(1985).
n,1,1. Alkalinity;
The alkalinity was determined according to the Standard Methods for the
>
Examination of Water and Wastewater (SMEWW, method No. 403) by titrating the water
0
1--4
sample with hydrochloric acid (0.02 N) to a preselected pH value of 4.5. _T_h_ e procedure
^
^--*
was as follows:
4
EID103198
3
i) Take 100 mL of the water sample and transfer it to an Erienmeyer flask. ii) Prepare the titration assembly (Le. a 25 mL buiet, magnetic stirrer and pH meter
apparatus) and fill the buret with standard Hd (0.02 N).
iii) Titrate the sample to the end point, pH of 4.5, without recording the intermediate pH values and without undue delay.
iv) As the end point is approached, make smaller additions of acid and be sure that the equilibrium pH is reached before adding more. dtrant
v) Record the total volume of acid consumed. vi) Calculate the alkalinity (in mg CaC03/L) as follows:
AxNx50,000 AAlHkalrini' ty, (i mg C^ a^C03 /irL>) = ---------------
where. A, N, and V are the volume oftitrant, normality of the acid consumed, and volume of the sample, respectively.
It. 1.2. Conductivity: The conductivity of the water sample was determined by a conductivity meter
(Markson ScL Inc., model ElectroMark analyzer). The procedure was as follows: i) Record the conductivity of deionized water before sample measurement This is
to be substracted from sample measurements. ii) Insert the probe into the water sample and stir for 3 minutes. Read and record (in
triplicate) the conductivity in piano/cm.
H.1.3. Total dissolved solids:
>
CO
The total dissolved solids was determined following method No. 208.B described
S
0
in the Standard Methods for the Examination of Water and Wastewater (SMEWW). The 2^a
procedures are presentedas follows:
EID103199
^
i) Heat the evaporating dish to 180C for 1 hour in an oven; stone the evaporating dish in the desiccator until needed, weigh the dish immediately before use.
ii) Filter the well mixed aliquot sample with No. 40 filter paper (Whatman), transfer the filtrate to the evaporating dish. Dry 100 mL of the filtrate in an oven at 180C until all
the water is vaporized. ui) Cool the sample in a desiccator and weigh until a constant weight is obtained.
Calculate the total dissolved solids by the following equation:
-'snw r ' w,?
^
.mg
_of total
- . . . . dissolved solids/L =
- ^QQOX(A-"B) sample volume (mL)
where: A= weight of dried residue plus dish (mg), and B= weight of empty dish (mg).
'.;,; ......
n.1.4. Analysis of fee major cations: The air-acetylene flame atomic absorption spectrophotometty method (SMEWW,
method No. 303A) was followed for the analysis of Na+, K+, Mg+2 and Ca+2 in the water
- ^a;
. >?mw\
,,,,,
samples. Atomic absorption spectrophotometer (Perkin Elmer model Zeeman 5000 with .a ,,,,,?;;>,, A-50 auto sampler) was used. The experimental procedures were as described below:
,. ;(% <msw
i) Prepare a calibration curve using known concentrations of the desired metal to be
,y,
analyzed. Read and record (following the instructions of the operation's mannual) the
absorbances of the standard solutions.
ii) Read and record the absorbance of the water samples (generally in triplicate) and
check if the absorbances fit in the range obtained for the calibration curve.
>
iii) If the recorded absorbance is higher than the calibration curve limits, further
2
o
dilution of the water samples is performed,
o
iv) Calculate the concentration of the element in question using the linear regression
equation obtained from each calibration curve.
EID103200
n.1.5. Analysis of the minor cations: 3
Essentially, the same method (SMEWW, method No. 304) described above was used to determine the concentrations of minor cations and trace heavy metals (Fe(II), Mn(n), Pb(n), Cu(D), Cd(n), Ni(n), Zn(D), and CoffQ). Due to the low concentration of these species in the water samples, it was necessary to use the electrothermal atomic absorption method (graphite furnace). An atomic absorption spectrophotometer (Perkui Elmer Zeeman 5000) equipped with a graphite furnace (model HGA 560) was employed for these analyses.
Detailed procedures are essentially the same as described above for the analyses of major cations.
n.1.6. Determination of carbonates: The Standard Methods for the Examination of Water and Wastewater (SMEWW,
method No. 406C) was used to calculate the concentrations of carbonate species, i.e. C02. COs", and HCOs" based on the chemical equilibrium relationship among-ftese carbonate
species in natural water systems. The concentration of bicarbonate is calculated by the following equation:
^T - SO*^1'11'1^
a B = [HC03-](mgCaC03/L) = a94*10^-10)
where T and pH are alkalinity (ing CaCOs/L) and original pH of the water sample.
The free COa is calculated by the equation:
A = ICOzlftee (mgCaC03/L) = lO+B*^6-1'10
EID103201
The carbonate concentration is calculated by the equation:
C = [(X^-KmgCaCOa/L) = 0.94*B*10<PH-10)
The total carbonate concentration is calculated by the equation:
[COaltoiai (mgCaCOa /L) = A + 0.44 *(2B + C)
IL 1.7. Analysis of chloride: The chloride ion concentration was measured by the Potendometric method, using a
chloride ion selective electrode (Orion Company, model 94-17B). The experimental
procedure was as presented below:
i) Set up the potentiometric apparatus, which includes the potentiometer, the
reference electrode (e.g. Orion Model 90-02 double junction reference electrode), the Cl"
Aoitselective electrode and me magnetic stiner system,
f^^"^' s-
<A
ii) Prepare a calibration curve using known concentrations of NaCTMIutions under
constant ionic strength of 0.1 M ofNaNQs.
iii) Read and record die potential (in mV) for each solution while keeping the
sample stirred.
iv) Plot me logarithmic of potential (millivolt) measured as a function of the chloride
concentration.
v) Read and record the potential of me samples and by linear regression analysis of
the calibration curve, find the concentration of Cl' in die water samples.
n. 1.8. Analysis of sulfate: ww
o
The analysis of sulfate was executed by a turbidimetric method described in die
^
S
Standard Mediods for the Examination of Water and Wastewater (SMEWW, method No.
EID103202
426C). The basic principle of the method is the precipitation ofsulfate ion (S042') in acetic
acid medium with barium chloride so as to form barium sulfate crystals of uniform size. Light absorbance of the BaS04 was measured by a photometer at 420 nm and the S042-
concentration was determined by comparison of the reading with a standard curve. The
procedures were as follows:
i) Prepare the buffer solution dissolving 30 g of MgCl2.6H20, 5 g of CHaCOONa.SHzO, 1.0 g of KNOa and 20 mL of acetic acid (99%) in 1000 mL of
distilled water.
ii) Prepare the a calibration curve using known concentrations of NazS04 solutions. iii) Mix 100 mL of sirifate containing solution with 20 mL of the buffer solution iv) Add a spoonful of BaClz crystals, begin timing and stir for 60 seconds at
constant speed.
iii) Pour the solution into a cell and read the absorbance of the calibration curve
solutions and samples (in triplicate) at 420 nm in the spectrophotometer (Hach-Company,
model DR/2000).
?
n. 1.9. Analysis of nitrate:
The N03' analysis were done by using UV spectrophotometric method described in
the Standard Methods for the Examination of Water and Wastewater (SMEWW, method
No. 418A). Measurement of UV absorption at 220 nm enables rapid determinatloiwfffi
nitrate ions. The experimental procedures were as below:
i) Treat the sample by filtering it through a 45 y.m membrane filter and adding 1 mL
ofHCHN.
ii) Prepare calibration standards in the range of 0 to 7 mg NOa'/L.
iii) Read absorbance against redistffled water set at zero absorbance using a UV-VIS
a
o
i--*
spectrophotometer (Peridn Elmer, model 139) at wavelength of 220 nm.
M
9
EID103203
n.1.10. C8 analysis in the liquid phase:
The concentration of C8 in the aqueous solution was measured by Gas
Chromatograph equipped with an Electron Capture Detector (HewUet-Packard 5880 n Gas
Chromatograph with HP 19303 Electron capture detector). All aqueous samples were
concentrated by freeze and drying (lyophilization) process to remove the water and permit
the derivatization. Methanolic HC1 was added to the dried residual as the esterification agent
along with perfluorodecanoic acid (C10) as an internal standard. Hexane was added to the
solution mixture to extract the methyl ester from the aqueous solution. The organic phase 3
was then ready for the gas Chromatograph (GC) analysis.
The detailed procedures were as follows:
i) Place 1 mL of aqueous sample into a lyophilizer (Labconco, bench-top freeze and
drying chamber). A vacuum pump (Maxima, Model D8A) is connected to the drying
chamber to reduced the pressure to around 3 x 10 -4 torr.
<
ii) Dry the samples completely. This process takes about 12 hours. The dried
.
;
samples are then ready for the derivadzation.
iii) To the dried residual, add 1 mL of methanoUc HC1 (3% HC1 in methanol) along
with 0.2 mL of a 10 ppm C10 solution as an internal standard to begin the derivadzation
process.
iv) Keep the sample in a thermostat for 1 hour at 65 C to allow a complete
esterification reaction.
TO,
v) After cooling the sample down to room temperature, add 1 mL of distilled water
and 2 mL of hexane. Shake the mixture well to allow the extraction of the C8 from the
aqueous phase. The organic phaseis men ready for the GC analysis.
vi) To analyze the hexane extract, set the GC conditions as follows:
E
- Column: DB-210 (50% trifluoropropyl. 50% methyl) 30 m x 0.25 mm
^
internal diameter, 0.5 mm film thickness (J & W Scientific).
|5
- Temperatures: Injection port
200 C
Detector
225 <C
10
EID103204
Oven
initial rate final
60C 20C/min 200 C
- Cairier gas: 90% argon/10% methane
Column head pressure 12 psi
- Injection volume: 1 pL
- Run time: 25 min
vii) Prepare a calibration curve with known concentrations ofC8 and plot the peak area rado of the C8 to the internal standard C10 (area counts C8/area counts C10) versus
concentration ofC8. The statistical method of linear regression is then utilized to compute
the concentration of the ammonium perfluoro-octanoate in the samples.
11.2. Characterization of the soil samples:
in- "
^ <'
With exception of specific surface area, pHzpc. hydraulic permeability and C8 analysis in the soil samples, all the other characterization procedures were extracted?ftm the Methods of Soil Analysis, provided by the Agricultural Experimental Station of University of Delaware (1991).
'% s"'
'
'
PL,2.1. Composition analysis:
The composition of site clay material was analyzed by the sedimentation
(hydrometer) method as described below.
i) Pretteat me soil samples by grindingand sieving to make sure that the diameter of
the soil particles does not exceed 2 mm.
>
a
ii) Take 50 grams of the ground soil sample and add 100 mL of 5% sodium
2
o
CT\
hexametaphosphate.
^
iii) Transfer the suspensionto a sedimentation cylinder, insert a plunger and mix the
contents thoroughly.
11
EID103205
iv) About 15 seconds after mixing the suspension, lower the hydrometer into
suspension, and after 40 seconds, read the scale at the top of the meniscus. Record the
hydrometer value. Also record temperature of the sample and a blank without soil at the 40
seconds time mark. From these values, the percentage of sand can be calculated.
v) After 2 hours of standing, lower the hydrometer into the sedimentation cylinder
again and record the hydrometer value, then record the temperature of sample and blank.
From these values, the percentage of clay can be calculated.
The equations for the calculation of the soil composition are as follows:
% Sand =100
flOOx (hydrometer reading at 40 seconds)^
|_
(corrected weight of soil)
J
100 x (hydrometer reading at 2 hours)
.Clay=
(corrected weight of soil)
iilh
Silt = 100 - (% Sand + % Clay)
where; corrected weight of soil as oven dry weight of subsample x 50g air - dried weight of subsample
.>,' dry weapil if'^ ^w!
n.2.2. Soil pH: The pH measurements were made in 0.01 M CaCl2 solution. The procedures were
as follows. i) Air-dry the soil sample and sieve through 2 mm sieve to remove the coarse soil
fraction.
ii) Weigh 10 grams of the pretreated soil sample and mix with 10 mL of 0.01 M CaCl2. Mix thoroughly and let the sample stand for at least 1/2 hour but not more than 1
hour. iii) Record the pH value with a pH meter.
a-Steve mi-oue!
>
CO
I
12
EID103206
H.2.3. Soil organic matter: 0
SoH organic matter was determined by the loss of weight on ignition (L. 0.1.)
method. The method is described below:
i) Take 1 cm^ of air dried soil sample, sieve through 2 mm sieve and place it into a 30 mL beaker.
ii) Dry the soil sample at 105 C for two hours and record the weight of soil sample plus beaker with an accuracy of 0.001 g.
3 iii) Place the sample in an oven at 360 C for two hours. Let the sample cool down
to 105 C and maintain at this temperature until weighing. iv) Weigh the beaker with the ash in a draft-free environment to 0.001 g.
O.M.W^-^-^-^100 Wb,-Wb
where:
,w.
Wfa = weight of beaker,
Wbs = weight of beaker plus soil before ashing,
Wfaa = weight of beaker plus ashed soil.
'"s
H.2.4. Son effective cadon exchange capacity:
a) Determination of the exchangeable cations:
i) Weigh 10 g of soil sample into a 100 mL polyethylene cup and add 50 mL of 1 N
| ammonium acetate (NI-HOAc) to the cup as a buffer solution to maintain the solution pH at
7.0. .
ii) Shake the cup for 30 minutes. Filtrate the suspension through No. 40 filter paper
o
M
(Whatman) and use 25 mL of 1 N NBiOAc again to wash the filter paper.
13
EID103207
iii) Collect the filtrate and determine the potassium, calcium and magnesium concentration by atomic absorption spectrophotometer.
b) Determination of exchangeableacidity: i) Weigh 10 g of soil sample into a 125 mL Edenmeyer flask, add 25 mL of 1 N
KC1 solution and mix well.
ii) Filtrate the suspensioninto a 300 mL Erienmeyer flask.
iii) Add 4 drops of phenolphthalein indicator and titrate the KC1 solution with the standard 0.01 N NaOH. At the end point of titration, record the volume of NaOH used.
iv) Get the exchangeable acidity in (meq/lOOg).
c) Effective cation exchangeable capacity (ECEC): The sum of the concentrations of exchangeable potassium, calcium and magnesium
and the exchangeable acidity is the effective cation exchangeable capacity (ECEC).
n.2.5. Moisture content:
. x ,;,
The moisture content determination was done as follows.
i) Weigh 1 0.0001gofsoil on a tared aluminum plate.
ii) Put me soil sample in oven at 105 C for 24 hours to dry.
iii) Take the sample from the oven and place to a desiccator to let cool down to
room temperature. Measure the weight of the dried soiL
iv) The moisture content can be calculated as the follows:
MW^^'^^ ^wet soil ~
xlOO "pia(e
J
where
M(%)= moisture content, percentage by weight
Wwet soil = weight of original soil sample + aluminum plate
14
EID103208
^BIP'
.,-)
iSiffi!S\'
Wdry soil = weight of the ashed soil + aluminum plate Wplale = weight of the aluminum plate
IL2.6. Specific surface area: The specific surface area of the soil sample was determined by the BET-NZ gas
adsorption method using a model QS-7 Quantasorb surface area analyzer (Quantachrom
Co., Greenvale, NY. model QS-7 Quantasorb)^
The multipoint BET equation (Brunauer, Emmett, and Teller, 1938) is used to
calculate the specific surface area.
^C 1 ^(C-l) P ^ 1
X(p^-l) xm(^ po
where
X = mass of adsorbate (N2) adsorbed at relative pressure P/Po, P = partial pressure ofadsorbate (N3), PO = saturate vapor pressure of adsorbate (N2), Xm = mass of monolayer coverage of adsorbate adsorbed, and C = a constant relates to the heat of the adsorbate condensation and heat of
adsorption.
Because the adsorption data from Quantasorb is often accompanied by a non-
Gaussian tailing pattern, particularly on porous samples, e.g., soil at high N2
concentrations, the desorption signals are always preferable and used in the analysis of
>
^ specific surface area and pore size distribution. The desorption signal is calibrated by o
injecting a known volume of nitrogen gas into the machine with signal obtained
S
t0
^
accordingly. Based on adsorption and desorption data, me specific surface area can be
obtained.
15
EID103209
;)
g.2.7, pHzEg The pH of zero point of charge was determined as follows: i) Take the soil samples from the containers, dry at 105 C, grind and sieve through
U.S. mesh No. 100 (150 urn). ii) For each sample, prepare solutions of 0.05 g/L of the pretreat soil under three
different ionic strengths e.g. 1 x 10-3,1 x 10-2,I x 10-1 M of NaC104.
.3
in) Measure the zeta potential (Q with a zetameter (Laser Zee model 500) as a
function of pH values ranging from 2 to 9. Adjust the pH of the solutions using HC104 and/or NaOH at various concentrations.
iv) Plot the t, values vs. pH for me three different ionic strengths. The pHzpc is then obtained at pH of zero zeta potential.
H.2.8. Hydraulic permeability: The hydraulic permeabilities of the soil samples were measured by the constant
head method (Fetter, 1980). The soil samples were collected from DuPont Washington
wy^'
Works ADPS-1 site depth (23'-25') and ADPS-2 site depths (0'-5'), (5'-10'), (15'-201),
(20'-251). The constant-head permeameter apparatus is shown in Figure 1 and the
following procedures were employed to obtain the hydraulic permeability:
i) Air dry me samples at room temperature.
H) Fill the bottom section of me column with the dried soiL
iii) Supply water to the regulated reservoir in order to keep the liquid level constant
g iv) Collect the water overflow from the column after passing upward through the &S
soil media,
g
s
v) Let enough water flow through the soil media until a constant flow rate is
oo
obtained.
16
EID103210
plot the volume of water as a function of time.
vi) Record and
permeabilitbyy Darc/s law. The equation is as follows:
vii) Compute the hydraulic
K ^ "- Ath
where:
K = permeabilitcyoefficient (cm/sec) V = effluent volume in time t (cm?) L = length of the soil sample (cm)
sectional area of the cylinder (cm2)
A = cross
h = hydraulichead (cm)
t = elapsedtime (sec)
IL2.9. C8 analysis in the soil:
proceduresdeveloped by CHzM ;
determined according to
The C8 in the soil was
Hffl Company.
experimentaplrocedurewas as follows:
u
Extract
The
homogenizedsoil sample into a tared 400 mL beaker.
i) Weigh 10 grams of
memanoVmethylen1e:1 (V/V).
the sample with 100 mL of
Sonic dismembrator, Fisher Company,
ii) Sonicate the sample (sonicationunit from of operation with 50 % duty cycle.
Model 300) for 180 seconds using the pulsedmode
small piece of glasswool on the
filter funnel for each sample. Place a
sulfate
iii) Prepare a
approximatel5y0 of anhydrous powderedsodium
bottom of the funnel and transfer
prewash the filter funnel with
Take a vacuum flask only to
flask
^
into (he funnel.
Attach a clean 500 mL vacuum
methanol/methylen1e:1 (V/V) immediatelybefore suosne.ication. Extract the sample remaining TM*
to the funnel and decant the extract &om me first adding 100 mL of fresh extracting 'g0^
in the beaker once again as described previously,
17
EID103211
solvent After the second sonication, pour the entire sample from the beaker into the filter
funnel and rinse with few milliliters of extracting solvent to complete the transfer.
a
iv) Assemble a Kuderna-Danish (KD) apparatus (500 mL evaporative flask, 10 mL
concentrator tube and three ball macro Snydercolumn) and transfer it to the filtered sample
extract along with 2 boiling chips. Place the unit on a steam bath with the concentrator tube
partially immersed in the hot water. Concentrate the sample until the apparent volume in the
concentrator tube is nearly 1 mL.
v) Remove the KD apparatus from (he steam bath and add 100 mL of fresh
dichloromethane directly down the Snyder column. Reconcentrate the extract again to an
apparent volume of 1 mL, remove the KD apparatus from the steam bath and allow the
glassware to cool for 5 minutes.
vi) Disassemble the KD apparatus (replacing the Snyder column by a 24/40
stopper) and transfer the methylene chloride concentrate to a 4-dram vial. Add 6 mL of 1M
A: ;
NaOH to the concentrator tube before reconnecting it to the KD flask. Gently rotate the
apparatus to rinse the interior walls. Collect (he rinse liquid to the 4-dram vial. vii) Secure the cap on the 4-dram vial and shake vigorously for 30 seconds. Briefly
>' ,..,,.
.;'
,; i,-
centrifuge the vial to assure a good phase separation and discard the dichloromethane
. > ,.,*;(- way.-i&
phase.
viii) Adjust the pH of the sample extract to less than 1.5 using 1+1 sulfaric acid.
Verify die pH with pH indicator paper.
t
ix) Add 5 mL of ether into the vial containing the acidified sample. Recap the vial
;
and shake vigorously for 30 seconds. Transfer the upper ether phase to a micro KD
apparatus (25 mL evaporative flask, 2 mL receiver and two-ball micro Snyder column).
>
Repeat the last step, combine the ether extractwith the previous ether extract and add 0.1
o
mL of concentrated ammonium hydroxide. Take the KD apparatus to a steam bath and
o
concentrate to approximately 0.5 mL. Remove the sample from the steam barn and allow to
.j cool.
18
EID103212
x) Transfer the concentrated solution quantitatively using 0.5 mL of acetone to a 4dram vial and further concentrate the sample to dryness using a nitrogen gas stream.
xi) To the dried residual, add 1 mL of methanolic HC1 (3% HC1 in methanol) along with 0.2 mL of a 10 ppm C10 solution as an internal standard to begin the derivatization process. Keep the sample in a thermostat for 1 hour at 65 C to allow a complete
estenficadon reaction.
xii) After cooling the sample to room temperature, add 1 mL of distilled water and 2 mL of hexane. Shake welTto allow the extraction of the C8 from the aqueous phase. The upper organic phase is then ready for the GC analysis.
xiii) Analyze the samples using the same GC conditions as described in section n.1.10.
IL3. Adsorption/desorption experiments:
-,
hi order to study the affinity between the C8 and site soil materials, batch
adsorption/desorption experiments were conducted. The influence of an electrical field on
the adsorption was also investigated by continuous flow experimenteAxr:
IL3.1. Soil sample preparation: The soil was collected from DuPont Washington Works ADPS-2 site, depth range
from 0.5 feet to 30 feet. The samples were air dried at room temperature and sieved to collect particles with a mesh size of 150 urn (ASTM No. 100) or smaller. The sieved soil samples were preserved in labeled plastic bags until used.
19
EID103213
B.3.2. Patch adsorption experiments;
The influence of pH, temperature, initial surfactant concentration, and soil/water
ratio on the C8 adsorption onto the soil samples were studied. The batch adsorption
experiments weie conducted as follows:
.
a) The pH effect: i) To a series of plastic bottles, add the desired amount of soil and 90 mL of C8
solution in 0.1 M NaC104 as electrolyte.
ii) Adjust the pH of each bottle from 2 to 10 with NaOH (0.1 M) and HCI04 (0.1 M). Complete the volume to 100 mL with the C8 solution.
iii) Place the bottles in a shaker and shake for 24 hours. iv) Measure and record the final pH of the suspensions. v) Collect and filter the supematants through a 0.45 urn membrane. vi) Analyze the filtrates for residual C8 concentration.
-'"^t
b) Temperature effect:
w;r<;.in,-c cits.-.
To study the temperature influence on'the C8 adsorption, the same experimental
procedures as decribed above were applied; except that a thermostatic shaker was used.
Experiments at temperatures of 10C and 45C and two different soil/water ratios (0.01
and 0.05) were accomplished.
c) Soil/water ratio effect:
Five different soil/water ratios (g of soiVmL of solution) including 0.005,0.01, 0.02,0.05 and 0.1 were adoptedto examine their effects on C8 adsorption. Once more, the
same above procedures were employed.
20
EID103214
d) Initial concentration effect:
Seven different initial C8 concentrations (10,20,30,50,100,150, and 200 ppm) were used to test the influence of C8 concentration on the C8 adsorption behavior. The
same experimental procedures as described previously were utilized.
n.3.3. Batch desorption experiments:
Desorption experiments were done using the soil samples from the ADPS-2 site, ^
depth 0.5 to 5 feet The procedures were as follows:
i) To a series of plastic bottles, add 5 g of soil and 90 mL of C8 solution in 0.1 M
NaC104 as electrolyte.
3
ii) Adjust the pH of each bottle to 2 with NaOH (0.1 M) and HC1C4 (0.5 M).
Complete the volume to 100 mL with me C8 solution,
r
iii) Place the bottles in a shaker and shake for 24 hours.
iv) Separate the water and the solid phase by centrifagation (5,000rrpm for 5
minutes) and discard the liquid phase.
,.,si-s ,,.,::
v) To each bottle, add 90 mL of NaC104 (0.1 M) solution.
"3
vi) Adjust the pH of each bottle from 2 to 10 with NaOH (0.1 M) and HC104 (0.1
M). Complete the volume to 100 nL with me sodium perchlorate solution (0.1 M). >
vii) Shake the plastic Basks for 48 hours.
-^
viii) Take aqueous samples at 6,24, and 48 hours.
w&,
ix) Filtrate the aliquots through a 45 p.m membrane and analyze them for C8
concentration.
H.3.4. Adsorption study under me electrical field: >
Adsorption study under electrical field was conducted by continuous flow
2
S
^
experiments using the soil sample from ADPS-2 site, depth0 to 5 feet
5
ss
(jj
21
EID103215
Three types of configurations were set up according to the placement of the eictrodes. The schematic diagram of continuous flow apparatus types A, B, and C are shown in Figure 2a, 2b and 2c, respectively. The continuous flow adsorption experiment for type A was performed without application of any electrical field.
Configuration B had the anode (positively charged electrode) installed at the influent side
and the cathode positioned at die effluent extremity while type C presented opposite arrangement. The tests were conducted by passing a 50 ppm C8 solution (in NaC104 0.1
M) through the soil samples (approximately 200 g of soil were placed in the cell). The
3 effluent was collected in graduate cylinder flasks and its volume was recorded. Effluent pH
and C8 concentration were determined and plotted as a function of time. Graphite rod
electrodes (Ultra Carbon Co. U7/SPK ultra "F" grade graphite) and a power supply
":)
(Power/Mate Corporation, model E-12/158) were used to provide a potential gradient of
1.0 V/cm over the soil samples,
.viw:
g.3.5. Analytical methods;
All the analysis of ammonium perfluoro-octanoate in the aqueous phase were
conducted following the same procedures previously described in section n.1.10.
+ ry'f-ctw1'-
3
n.4. Electro-osmosis tests:
11.4.1. Soil sample preparation;
Soil sample from ADPS-2 site, depth 0 to 5 feet was employed for the electro-
osmosis Tests I, n, IV and V. Sample from the same location and depth range of 5 to 10
>
w
feet
was
used
for
(he electro-osmosis
_
Test ffl.
A
section of
10
cm
in
length of undisturbed
^
o
soil sample was taken from the column (6.8 cm of internal diameter) and placed in the
S
3
central cylinder (also with dimensions of 10 cm in length and 6.8 cm of internal diameter)
22
EID103216
of the electro-osmosis cell (Figure 3). The electro-osmosis Test VI was executed with a
mixture of soils from the ADPS-2 (0 to 17 feet) and BGMW6 (0 to 2 feet). Some properties of the soil sample core and experimental conditions are shown in
Appendices A, B, C, D, E, and F for Tests I, n, ni. IV, V, and VI, respectively.
H.4.2. Electro-osmosis apparatus set up and testing:
,_, ,
Figure 3 shows the typical electro-osmosis apparatus employed in the experiment
The electro-osmosis cell consisted of three parts - anode container, central cylinder where
the soil sample was held and cathode container.
The volume of the containers were 650 mL for the electro-osmosis Test I and 125
mL for the Tests II and III. For the tests with pH control (TV, V and VI), the anode
container was 650 mL to allow the insertion of pH probe and feeding solution tubes while the cathode reservoir volume was 125 mL.
To separate the soil from the water solution, a set of two nylon meshes with a filter paper in between were used both in the cathodic and anodic reservoirs. The graphite electrodes were placed right behind the membranes. It was suggestedfor the tests under pHgr,, ;.," control that some space should be left between the electrodes and membranes at the anode container. The reason was to provide better mixing to the anode solution near the
electrodes.
After assembling the cell, both anode and cathode compartments were filled with
electrolyte solution (process water). Then the electrodes were connected to the power
supply to begin the test The electro-osmosis Test I was an exception, where initially only
me anode container was filled with electrolyte solution and the cathode reservoir was
empty; moreover, in the three first days of experiment, no voltage was applied to verify the
a
--*
magnitude of the hydraulic permeability.
u
23
EID103217
For all the tests, parameters such as water flow, current, pH at the cathode and anode reservoirs were monitored as a function of time. Water samples from the effluent and influent were taken and analyzed for C8 concentration.
At the end of the test, the soil samples were removed from the cell and sliced into 10 sections. Each section was analyzed for water content, pH and C8 concentration.
IL4.3. Electro-osmosis experiments with pH control:
n
^
The soil sample preparation, set up and testing for the electro-osmosis experiment
with pH control were essentially the same as" for the other tests. Figure 4 presents the
schematic diagram of the system used for the experiment The pH was maintained constant
at both tile anode and cathode reservoir using a pH controller equipment (model pH-22,
New Brunswick Scientific Co., Inc., Edison, NJ). Table n below outlines the different reagents (adds and bases) utilized and the pH in the electro-osmosis experiments.
Table n. Reagents used in the electro-osmosis experiments with pH control.
Test#
IV
V
VI
anode
PH
reagents
10
NaOH.HCl
10 Ca(OH)2,Hd
6
CaCOS, HC1
cathode
pH
reagents
10 NaOH,Hd
10 NaOH, Hd
10 NaOH.Hd
n.4.4. Moisture content effect on fee electro-osmotic flow:
Soil samples from RBLMW2 and RBLMW11 at depth from 10 feet to 12 feet were utilized for the moisture content study. The soil samples were dried in the oven at 52C for 12 hours and placed into a desiccator for 2 hours. Afterward, the dried samples were
24
EID103218
ground with mortar and pestle.The moisture content was determined right before packing the soil in the electro-osmosis cell (Figure 3). The anode compartment was filled with process water and the cathode container was initially empty. The electrodes were then connected to the power supply. The time required to saturate the soil column was recorded and the effluent volume emerged at the cathodic reservoir was monitored as a function of
time. H.4.5. Analytical methods: The soil moisture content was measured using the same procedure described in
section n.2.5. Soil pH was determined by the same procedures as in section n.2.2. C8 concentration in the soil was determined by the procedure developed by CHzM
Hill Co.. This method is thes wae as described in section H. 1.10.
J
0
o
25
'^'^
EID103219
III. Results and Discussions
in groundwater quality:
in.l. Analysis of the site
obtained for the analysis of the groundwater. As
Table summarizes the results
S042" and Cl- are present at high
expected, calcium and sodium, as wen as HCOs",
(ppb levels). The C8
concentrations and heavy metals are present at trace amounts
concentrationin me water sample was 113 2 ppb.
Characterizationof the site groundwaterquality: Table VI. I m
I
^---- determinations,unless indicated,
o
o\
of. 3
w
00
**
3
average
W of
k5 j
fd_e.te. rminatio
ns.
detenninattons.
*** average of 6
26
EID103220
Figures 5 and 6 show the concentration of the major cations and trace heavy metals, respectively. Figure 7 presents the anion concentration in the process water
sample.
The equivalent bar chart of the major ionic species present in the process water is illustrated in Figure 8. Prom the diagram, it is observed that the electroneutrality is
satisfied among the cations and anions.
III.2. Characterization of the soil samples:
HL2.1. Composition analysis: Figures 9 a, b and 10 a, b show
sedimentation method of two different sites -
.w,^
the soil composition obtained from ADPS-1 and ADPS-2. Composition data
from both sites show that the percentage of sand increases with the depth. The results of
the composition analysis of the soil sample is listed in the Table IV. Clay is the major
component at the top soil zone (depth < 10 ft) indicating that electro-osmosis technology
will be feasible for this legion.
m.2.2. Sofl pH:
fc.
The soil pH values were measured using 0.01 M CaClz as electrolyte. The soil pH
profiles (Figures 11 and 12) indicate that most of the soil is in the neutral pH region (pH
from 5.5 to 7.5) and the variation over depth is insignificant
^ ro.2.3. Soil organic matter;
Soil organic matter is an important component of the soil system. It can affect other
a
soil physicalpropertiessuch as specific surface area, adsorption capacity, and CEC. 2<T
iwij
so
27
EID103221
3 S
rprt 0
\'0f..
Figures 13 and 14 show organic matter content as a function of soil depth for ADPS-1 and ADPS-2 soil samples, respectively. The results indicate that the soil organic matter content decreases with increasing depth in both sites. The percentage of organic matter is closely related to percentage of clay as welL This suggests that the organic matter is strongly adsorbed by the clay portion.
m.2.4. Soil effective cation exchange capacity: Figures 15 a, b and 16 a, b show the depth distribution of effective exchange capacity and exchangeable cations for the samples from the ADPS-1 and ADPS-2 sites. In both locations, me exchangeable calcium is me predominant component in all sections of the soil profile.
..,,,,,,.
m.2.5. Moisture content:
- ^.H;".
The moisture content vs. depth for both sites. ADPS-1 and ADPS-2 is illustrated in
Figures 17 and 18, respectively. At the ADPS-1 location me moisture content is high^fewiy /-.
the top soil zone (about 18 percent) and low (about 2 to 5 percent) at the subsurface; !,,, ^,^.. section, then increasing again to about 15 percent just above the water table. At the ADPS-2
site, the highest water content of about 15 percent was found at the section from 5 to 10
feet deep.
.,; ,..
t.tu<
m.2.6. Specific surface area:
,aa,
Figure 19 to 24 show the BET plots of all soil samples analyzed. Table IV
summarizes the results of specific surface area of the samples tested. The specific surface
areas of the soil samples from the ADPS-2 site are fiom 10 to 22 m^g.
>
I
o
^0\
28
EID103222
ffl^jLpito
Figure 25 shows the variation of pHzpc with depth at the ADPS-2 site. The profile indicates that the pHzrc has a value approximately 2.0 to 2.7 over the entire depth.
Figures 26 to 31 show the zeta potential as a function of pH for all soil samples
tested. The pH of zero point of charge is obtained at the pH value where ^ is equal to zero. Since the application of electro-osmosis will be investigated in this project, it is
crucial to know the microscopic electrical properties of the soil samples. It has been .,, reported in the literature that the electro-osmotic water flow is directly proportional to the
zeta potential:
Q^ o4-in^iL
where e, ^,!,, TI and L are the dielectric constant, field strength, zeta potential, viscosity
and length. This equation shows that the electrical property of the soil will influence. ,nv;
directly the electro-osmotic process,
w 'ocs-.ss.
The other important aspect of soil ^ is the adsorption capacity for ionic species; asifa
which is closely related to t, of the soil particles,
y ip": v
HI.2.8. Hydraulic permeability measurements: Constant head penneameter was used to determine the hydraulic permeability for
(he soil samples from both ADPS-1 and ADPS-2. For each soil sample, results of the relationship between the cumulative effluent volume and elapsed time are shown in Figure 32 to 36.
The statistical method of linear regression technique was adopted to obtain the average slope and hence, the hydraulic permeability. The depth profile for ADPS-2 site is shown in Figure 37. As expected, the soil samples in the top 10 feet present very low hydraulic permeability (-10"6 cm/sec)due to the high clay content present in this area.
,.,m-
r,
s '4
>"* o
OS
(!>.
29
EID103223
0
ffl.2.9. C8 analysis: The concentrations of C8 in the unsaturated soil below the anaerobic digestion
b ponds are shown in Table IV. There is a general trend for the upper soil zone to have
higher concentrations of C8 as illustrated in Figures 38 and 39. Concentrations up to 33 10 ppm were detected at ADPS-2 site and 16 1 ppm in ADPS-1 site.
3 0
30
EID103224
-say
Table IV. Characterization of the soil samples.
:3
sample*
Con^oafiotianalysis pH QM
sod alt chy
(%) (%) ('3K)
(%)
BCBC MC
$neqfl00@ (%)
Sat
3SSL
^
pHac
hydr. (scn-
(anfea)
C8
cone.
(Epn)
ADPS-1
Qy-iy 36
34
31 7.5 1.9
&0
17.8
,,
16fcl
y-T
5
45
50 5.6 12
7.6
13
4fcl
9'-ir
28
34
38 5.9 11
6.9
4.1
,
5tl
ir-i3'
24
44
32 &7 L6
7.1
7.8
--
*^
15'-1T
52
22
26 &8 1.3
4.4
8.0
,,
.
^
2ff-22'
44
31
25 7.1 09
6.0
7.4
,,
,
23'-25'
88
6
6 6,4 01
2.2
11.6
,,
4x10-5
25'-27'
89
4
7
60 0.3
3.0
9.8
^
-
i^m?
28'-30'
88
0
12 6,1 Q5
16
11.5
,,
-
--
30'-32'
90
5
5
7.1 0.2
12
11.6
-
--
32'-34*
92
4
ADps-2
4
6.6 0
1.9
15.4
--
(y-y
36
35
29 7.5 1.9
9.9
7.9 l&O 11 4x106 333:10
y-iff
5
49
46 &5 1.5
6.3
15.3 21.9 11 2)d0<> 16t5
iff-iy
5
51
44 6.2 1.5
7.4
9.7 21.9 17
^
512
\s-w
50
30
20 5.4 1.3
5.2
4.8 10,8 15 6?d0-5 5t2
W-TS
46
42
12 5.5 0.6
83
5.9 17.2 14 4d04 512
25'-3(y
54
28
18 6.2 0.9
&2
13.9 9.5 10
-
02
* Each section represent the depthin feet below ground surface.
31
EID103225
III.3. Adsorption/desorption experiments:
m.3.1. The effect of pH on C8 adsorption/desorption:
a) Adsorption: Figures 40 to 45 show the residual C8 concentration in aqueous phase as a
function of pH for sou samples from the ADPS-2 site, from 0 to 30 feet of depth, and Figures 46 to 51 present the percentage of C8 adsorbed as a function of pH. From these diagrams, it is concluded that the adsorption varies substantially with pH. At low pH values (pH<2) the surfactant is highly adsorbed onto the soil and there is decreasing adsorption with increasing pH. The acidity constant of C8 is 2.9 and the pHzpc of the soil is between 2.0 to 2.5. The distribution diagrams of soil surface protonated species and C8 is shown in Figures 52, and 53 respectively. From these illustrations, one can observe that the negatively charged soil particles repel the perfluoro-octanoate ion at pH values higher than 3.0. As a result, the amount of C8 adsorbed decreases as pH increases. The
adsorption can be attributed to chemical interactions (probably hydrogen bonding) that are represented by the following equations:
OH+C7Fj5COO- - 90H""- OOCCyFis
or
90- +C7Fi5COOH -> SO- -- W)OCC^
where S.OH and S.O' represent neutral and negatively charged soil surface species,
respectively.
>
b) Desorption:
w
S Figure 54 a, b, and Figure 55 a, b show the C8 desorption results for the 5
ADPS-2 site, section 0 to 5 and 5 to 10 feet, respectively. The amount of surfactant -^
32
EID103226
desorbed was determined by analyzing the aqueous samples at 6, 24 and 48 hours of equilibrium time. The results demonstrated that a gteat amount of C8 was desorbed under alkaline conditions (pH>8), decreasing its concentration as pH decreased. This is in agreement with me results obtained in the adsorptionexperiment described previously.
The kinetic study indicated that the system reached an equilbrium within 6 hours and the C8 concentrations detected in the aliquots were almost the same as for 24 hours and 48 hours.
m.3.2 Effect of soiVwater ratio:
a) At constant pH: Figure 56 shows the results of C8 adsorption under different soil/water ratios. A
total of six sections of the soil depthprofile (ADPS-2) were tested. The pH was adjusted to 7.0 and the initial C8 concentration was 50 ppm. A slight increase in the .quantity of C8
adsorbed was observed by increasing the soiVwater ratio.
, .;
, , ,s<;s n
b) At varying pH: The influence of soil/water ratio (0.005.0.01,0.05,0.1 g/mL) on C8 adsorption
under various pH was investigated. The soil sample ADPS-2 (0'-51) was used for these experiments. The results are shown in Figure 57. The C8 adsorption behavior as a function of pH follows the same trend for all the soiVwater ratios studied except at soil/water ratio of 0.1 g/mL, when C8 is adsorbed even in the alkaline pH region.
33
EID103227
HL3.3 Temperature effect on the CR adsorption/desorption:
3 a) Adsorption:
Three different temperatures (10C, 25C and 45C ) were chosen to conduct the batch adsorption and desorption experiments. The plots of percentage of adsorption as a function of pH for each temperature are shown in Figures 58 to 60. Two different soil/water ratios (0.01 and 0.05 g/mL) were used to conduct the test Figures 61 and 62 show the results of the adsorption study under the three different temperatures (10C,
^
25C, 45C). From these graphs, it is viewed that there is a slight increase in the adsorption capacity with decrease in temperature.
\
"i
b) Desorption:
Figure 63 shows the C8 desorption under three different temperatures - 10C, 25C and 45C. The results indicate that more of the surfactant was desorbed. w^h^,;, . ^ increases of temperature, or C8 adsorption capacity decreases with increasing (emperato^ . ^ ^.. ,,.,,,;
PI.3,4 faitial C8 concentration;
Seven different initial C8 concentrations (10,20, 30, 50,100,150 and 200 ppm)
were used to test their effect on the behavior of adsorption at soil/water ratio of 0.05 g/mL.
Figures 64 and 65 show the residual C8 in the aqueous phase vs. pH at various initial
"^
surfactant concentrations. At C8 below 50 ppm, die extent of adsorption reached 100% at
pH value ^ 2.0. This is in agreement with the fact that the maximum adsorption only
occurs when the solution pH is lower than pHzpc of the solid surface. At pH values higher
than 5, almost no C8 was uptaken due to electrostatic repulsion between the anionic C8 and
^
a
the negative surface charge of Ae soil particle.
S
--A
A noteworthy observation is that the percentage of adsorption for initial C8
^;
concentrations above 50 ppm is higher than that below 50 ppm within the pH range from 3
34
EID103228
a
to 9 (Figures 66 and 67). This can be attributed in part to the hydrophobic-hydrophilic nature of the ammonium perfluoro octanoate. At high C8 concentrations, the adsorption
3 process is brought by nonpolar interaction, in addition to specific chemical bonding, ^ between C8 and the soil surface. Therefore, the percentage of adsorption for initial C8
concentrations above 50 ppm is higher than those for 10,20,30 ppm. Figure 68, and 69 illustrate the partition coefficient of C8 as a function of pH.
The partitioncoefficient ofC8 was calculated by the following equation:
@
KK- d--^c
Where q = accumulated concentration of C8 in soil (ing/Kg), C = C8 concentration in the bulk solution (mg/L), Kfl = partition coefficient (L/Kg).
is ,;-i?
m.3.5. Adsorption under electrical field: "
-.y'..aSiMa-Ae'lSafsatlrMicSaAlfJi&&lltdt.-i
In order to study the effect of electrical field on the adsorption of C8, a continuous
flow method was employed. Figure 70 shows the pH of the effluent for the 3 types of adsorption systems. The effluent solution in system A did not show any pH variations
W?'n<
during the entire experiment. A gradual increase of pH was observed for the solution
effluent obtained in the adsorption system type B. The pH of the effluent in system C
.^
dropped from 7.0 to 2.4 within 6 hours of (he test. The reasons for the pH changes were
attributed to me redox reactions of water at the electrodes.
As indicated above, pH plays an important role in C8 adsorption. Therefore
changes in pH under the electrical field can alter the extent of C8 adsorption. Figure 71
demonstrates that during the 6 hours of adsorption experiment under electrical field, the
amount of C8 retained in the system C was higher than mat for the systems A and B.
^
>-->
^
35
IS-
'-1
EID103229
Figure 72 shows the plot of accumulated flow as a function of time. The three types of adsorption systems did not exhibit appreciable differences in effluent volume, indicating that the electrical potential had little influence on the flow rate. The only important effect of the electrical field was the pH modification which in turn affects the C8
adsorption.
y ^
,
III.4. Electro-osmosis tests:
ffl.4.1. Electro-osmotic water flow: Figure 73 shows the cumulative electro-osmotic water flow as a function of time
for all the tests performed.
For Test I, no voltage was applied during the first 3 days and consequently no
water flow was observed. This indicates that the soil has low hydraulic permeability. Thus, the subsequent water flow could be attributed exclusively to the electro-osmosis process. However, no water flow was found at a period of four days after the voltage was applied possibly because the soil system needed to be adjusted to someconditions such as, moisture content and ionic distribution. It is important to remember mat initially me cathode compartment was empty and the moisture was provided entirely from the anode side. Among all the tests. Test I presented the smallest amount of water flow. In 30 days of experiment, about 160 mL of liquid was collected at the cathode compartment
Test n produced higher amount of flow than the previous test. For this test, a potential gradient of 1.5 V/cm was used. The electro-osmotic cell was modified in a way that both cathodic and anodic reservoirs were initially filled with electrolyte solution. The necessity of this procedure was to better simulate real field conditions and it was utilized in further tests. Water flow emerged at the first day of experiment and around 900 mL of liquid was passed through the soil core in 54 days.
,.,^, ,-.^, ,,
.Kay;;;; yw. (= & , ^^at^Q (ay;
y ;.
;,^
;^-;&;.
, ,_ :
y.;
^
w
S
g
o\
i^
36
EID103230
Figure 73 shows that nearly 330 mL of water was collected at the cathode side for
Test in. This value is small when compared to the water flow obtained in Test II. One
of the reasons is that the soil sample from ADPS-2, depth 5 to 10 feet contained a considerable amount of wax that had been used to seal the drill core during sample
collection.
A high amount of flow was observed in Test IV during the 23 days of experiment
when compared to previous tests. This test was executed under pH controlled conditions
(see Table ID) and 1100 mL of water was passedthrough the soil sample core. At high
pH values, the soil surface is negatively charged (pHzpc = 2.5 - 2.7),,and more solvated cations (that are responsible for the net water movement towards the cathode) arc present near the surface. Thus, higher water flow is expected at high pH values as the zeta potential of the soil is higher at higher pH. According to Casagrande (1949), the electro-osmosis
flow is proportional to zeta potential.
,.,
The cumulative electro-osmotic water flow as a function of time (Figure 73)
shows that in Test V, almost 500 mL of water was passer through the soil core. According to the results of the electro-osmosis Test IV, by maintaining the pH at 10, high
water flow would be predicted. Two of the reasons for the observed, contrasts can be
speculated as follows: a) the high pH conditions caused precipitation of some salts (e.g.
CaCOs) (hat coated the surface of the graphiteelectrodes, yielding a tow efficiency of the i
electro-osmosis process; b) increasing the calcium concentration, the ionic strength of the electrolyte increases substantially causing a diminishing of the zeta potential (see Figures
26 to 31) and consequently reducing the amount of water flow.
For test VI, similar occurrence was observed. The only difference was that (he pH
could not be maintained at 10 by using CaCOa at the anode reservoir. Consequently smaller
water flow than that for Test V was produced. Only 250 mL of water emerged at the
<>
cathode side in 31 days of experiment
\o 37
EID103231
m.4.2. Coefficient of electro-osmotic permeability ftg): Figures 74 a, b show the coefficient of electro-osmotic permeability as a function
of time for all the tests conducted. Tests I and in produced similar values of ke (1-3 x
10-6 cm^CV.s)), while Test n gave electro-osmotic permeability values around 5 x 10-6
cn^/O^s), as can be seen in Figure 74a. Among the tests under pH control. Tests IV and V presented values of ke up to 3-4 x 10-5 cm^/CV.s)while Test VI produced electro-
osmotic permeability values on the order of lO^cm^Cv.s).
nU3. Current density;
With the exception of Test IV, all other tests presented the same trend of current density as a function of time (Figure 75). Values up to 0.5 mA/cm2 were recorded at the
beginning of the experiments with gradual decrease as the tests proceeded. Test IV
produced current densities up to 2.3 mA/cm2 wilh gradual increase thefffist! VI dayss.ofeflie
test
ffl.4.4. Influent pH:
,,.
In Tests I, n, and HI, the pH of the influent (anode reservoir) dropped to values
around 2 and remained constant afterward (Figure 76a). The build up of acid conditions
at the anode was due to the oxidation of water represented by the equation (Acar, Y., etc., 1990):
2H;0 ----> 0, + 4H* + 4e-
To conduct die experiments under pH control, it was necessary to add base to the
anode reservoir. The pH for Tests IV and V were maintained at 10 with NaOH and
Ca(OH)2, respectively. For Test VI, CaCOs was used as the base and the pH could not ^
ffi
o
5
G\
<-h 0
38
EID103232
be controlled at 10; instead the pH was maintained at 6. Figure 76b shows the pH of the influent solution as a function of time for the tests under controlled pH conditions.
m.4.5. Efflnent pH: Figure 77a show the pH of the effluent solution as a function of time for the
Tests I, n and m. The effluent pH of the Tests I and in rose to values around 12 and
then dropped gradually due to the acid front generated at the anode. Test n presented a fairly constant pH (around 12) throughout the experiment, indicating that the electrolysis rate overcame the acid front at the anode. The basic condition at the cathode was caused by the reduction of water as follows:
21^0 + 2e- ----> Hi + 20H-
Hydrochlodc add was used to adjust the pH at the cathode (effluent) reservoir hi all the three tests under pH control. Figure 77b presents the pH of the effluent as a function
of time for Tests IV, V, and VI.
jn.4.^. C8 concentration at the effluent:
C8 concentrations at the effluent for all the tests conducted are shown in Figure
78. From this figure it is noticed that Tests I, in, V and VI presented very low effluent C8 concentrations. In me Test n, values up to 10 ppm were detected at the effluent solutions. Test IV exhibited the highest C8 concentration at the effluent reaching a
maximum at 10 days of experiment correspondent to 55 ppm. At 20 days, almost no C8
'..;:"
>,-
, ,,-,
n*;
could be found in the effluent solution,
us ysy uuo
ffl.4.7. C8 concentration at the influent:
The acidic constant for the perfluoro-octanoic acid is 2.9, indicating that at pH
values higher that 2.9, most of me C8 molecules are present in solution in an anionic form
>
(perfluoro-octanoate ion). Therefore it is expected that C8 molecules migrate towards the
o
anode during the electro-osmosis process. The graph of concentration of C8 at the influent
<->
39
EID103233
solution as a function of time for all the electro-osmosis tests (except Test I) is shown in Figure 79.
Tests n and in did not present notable amounts of C8 at the influent solution
because of the low pH condition. The C8 molecules at pH values lower than 2.9 have neutral charge and do not migrate to the anode.
Test IV also did not show significant C8 concentration at the analyte due to the
high amount of water flow towards the cathode that exceeded die electrical migration of the C8 molecules.
Low water flow and basic pH conditions were present in Tests V and VI, and
high amounts of C8 were determined at the influent solutions. Concentrations up to 90 and 40 ppm were detected for Tests V and VI, respectively.
m.4.8. CS removal: Figures 80 and 81 show the cumulative C8 removed at the cathode (in
milligrams) and the percentage of total C8 displaced from the soil at the effluent as a
function of time, respectively. It is observed that Test IV presented the highest removal
.. ww > ,
-.'
while the other tests did not show significant amounts of C8 at the effluent solution. About . .v sx a>h; a?'< .w
28 mg (88 %) of the ammonium perfluoro-octanoate was withdrawn from the contaminated
-
. ..,
soil by the electro-osmosis process in Test IV. For Tests I, V, and VI, low removal
,
,*si
was achieved and values up to 1.7 mg of cumulative C8 were removed (2.5 %). In Test
i
n, around 4.5 mg (18 %) of the surfactant present in me contaminated soil was removed.
It is observed that in Test in. only 1.2 mg of C8 was recovered at the cathode which
corresponded to 50 % of the total perfluoro-octanoate present in the soil. The amount ofC8
removed at the cathode (effluent) was related to the velocity of the water flowing through
the soil core due to the electro-osmosis process. Test IV had the highest water flow w
velocity and produced the highestC8 removal at me cathode.
^
0\
<y>
h->
40
EID103234
Among all tests performed. Test V and VI presented the highest C8 removal at the anode. Around 78 % and 63 % of C8 were recovered at the anode in Tests V and VI,
respectively. The explanation of these observations was already discussed in section IV.4.7.
m.4.9. Water content: The water content profile across the soil sample after the completion of the tests is
shown in Figure 82. Prom the graph it is noticed that generally, the water content is high at the anode side and gradually decreases toward the cathode. This observation is an indication that water has been withdrawn at the cathode side by the electro-osmosis process, yielding die build up of the water content profile across the soil core.
ffl.4.10. The pH profile: Figure 83 presents the pH distribution across all the soil samples tested as a
function of distance from the anode. Tests I, n, and in produced similar pH trends with
increasing values toward die cathode. The build up of acidic conditions at the anode and alkaline conditions at the cathode were previously discussed in sections IV.4.4 and IV.4.5.
No significant changes in pH were observed over the soil core in other tests performed under pH control. Fixed values ofpH arouQfl 10.5,9.0 and 6.0 were recorded
for Tests IV, V, and VI, respectively.
m.4.11.C8 distribution: The relative C8 concentration across die soil samples as a function of distance from
the anode after the tests were completed is shown in Figure 84. The horizontal solid line
at value 1 corresponds to the original surfactant concentration at the beginning of the <Q
S
experiments. Tests I, V and VI produced an accumulation of the contaminant at the S
0u\
middle section between the cathode and anode while in Tests M and IV almost no C8
w
41
EID103235
was found in the entire soil core. For Test n, an agglomeration of about 5 times the initial
concentration was observed at the region near the anode and very low concentrations were
detected at other sections of the soil sample.
The formation of concentration profiles is caused by three major components
affecting the C8 movement through the soil * the electrical, the convective and the sorptive.
The electrical factor is related to the migration of the anionic form of the surfactant towards
the anode; the convective component is attributed to the transport of the contaminant simply
by the water flow; and the sorpdve influence (also called retardation factor) is caused by the
adsorption of the C8 onto the soil.
It is noticed that Test I had low water flow rate and low pH around the anode side.
This indicated that the convective component and the electrical migration in the region close
to the anode were not significant Moreover, me retardation factor was prominent at the
sections of low pH. Consequently, an accumulation of C8 was observed halfway between
the electrodes,
-c ;.;,;;,
The same explanation could be applied to Test n except that the agglomeration
occurred at the region close to the anode. Higher potential gradient and longer test time than
Test I possibly was the reason for the observed contrast
,, ossiM'
Test m was the longest test and almost no C8 was detected in all sections of the
soil sample,
-^-w
The convective component was the major factor mat contributed to the removal of
the C8 in Test IV. This test presented the best removal rate and it is estimated that almost
no C8 was left in the soil.
Test V and VI also showed an accumulation of C8 at the middle section of the
gY^
soil core. This was caused by the reasons cited above for Test n, except that the sorptive
5a
factor was less significant
^
o^ \
t-
42
EID103236
m.4.12. Mass balance: The following Table V exhibits the results of the C8 mass balance obtained for the
electro-osmosis tests executed.
Table V. Mass balance ofC8 for the electro-osmosis tests.
Test#
C8 removed
at the cathode (mg)
C8 removed
at the anode (mg)
C8 remained
in the soil (mg)
Total (mg)
Original C8 in the soil
I
0.6
9.1
n
4.5
0.4
m
1.24
1.17
IV
28.3
3.3
v
1.7
54.1
VI
0.2
25.7
* range of C8 mass originally in the soiL
18.8 20.1 0.07 0.8 13.4 15.3
28.5 25.0 2.48 32.4 69.2 41.2
(ppm) 3310 33+10 16+5 3310 3310 67+11
(mg)* 15.6-29.2 13.7-25.6 3.96-7.57 14.7-27.5 14.4-26.9 35.9-50.0
ffl.4.13. Moisture content effect on electro-osmotic flow: Two tests with different moisture content (1% and 12%) and one test without
electricity were compared to evaluate the the effect of moisture content on the electroosmotic flow. The time required to saturate the soil column, indicated by the presence of effluent at the cathode reservoir was recorded. The plot of cumulative effluent volume as a function of time is shown in Figure 85. From the graph it is noticed that there is no significant difference on the soil saturation time among the three tests performed. However, after the saturation time, higher water flow rate was observed for the test with 12 % of
initial moisture content.
43
EID103237
IV. Conclusions and Recommendations
Based on the laboratory experimental results obtained, the following conclusions can be
deduced:
1. Chemical analysis demonstrated that Ca^*-, Na"*", HC03-, S042- and Cl- are the major
ionic species present in the plant groundwater sampled. Other properties such as
alkalinity, pH, conductivity and total dissolved solids are in accordance with typ|c.aL,,i,,. ,,,; groundwater characteristics.
2. Low concentration of C8(1132ppb) was detected m me groundwater sample. 3. The soil composition analysis from below the anaerobic digestion ponds showed that
high percentage of clay is present at the top soil zone (depth < 10 feet), a region where
the electro-osmosis process can be successfully applied.
4. High concentrations of C8 were found in the soil samples in the top 10 feet at ADPS-1
r
.
and ADPS-2, at around 16 and 33 ppm, respectively. This is the area where -the,,, .1 i v,
electro-osmosis process needstb and can be applied.
;:< noEA to rno e&n cue s,'.t.
5. As expected, specific surface area, organic matter content, and cation exchange capacity
, ,,
influence the composition analysis, i,e., higher percentage of clay results in higher specific surface area, organic matter content, cation exchange capacity, C8
concentration, and lower hydraulic permeability.
6. Adsorption studies indicate (hat the pH greafly affects C8 soil adsorption. The lower the pH, the more C8 adsorbed. There is almost no adsorption when pH is greater than 8.0. The addity constant of C8 is 10"2-9 and the pHzpc is in the range of 2.0 to 2.5. An
.seic v: ^i;.
electrostatic repulsion between anionic C8 and negatively charged soil surfaces occurs ^
gCO
at pH values higher than 3.0. As a result, me extent of C8 adsorption decreases with
increasing pH. The same reasons can be used to explain the extent of desorption g^
CT\
increases with the increasing pH.
44
EID103238
8. Temperature is an important factor on the adsorption and desorption. The higher the temperature, the more C8 dissoluted from the soil, making it difficult to retain C8 on the soil surface.
9. The initial C8 concentration in the aqueous phase affects adsorption substantially. While the C8 concentration is less than 50 ppm, the extent of C8 adsorption is diminished significantly at pH greater than 5.0. However, when the C8 concentration is greater than 50 ppm, the percentage of C8 adsorbed is higher within the pH range of 5.0 to 8.0. The possible reason is the hydrophobic effect that makes the C8 easier to be
retained on the soil surface.
10. The results of the adsorption experiments under electrical field indicated mat the Type C (where (he cathode is at the influent side and the anode at me effluent side) exhibits the most C8 retaining capacity and effluent pH is the lowest Inversely, Type B adsorption system (where the anode is at the influent side and the cathode at the effluent side) gave the highest effluent pH and showed the lowest C8 adsorption affinity. The reasons for effluent pH changes were found to be caused by the rcdox reactions of the water at the
electrode surface.
11. Electro-osmosis experiments performed without pH conditioning showed little C8 removal. In these tests, significant amounts of surfactant remained in the soil presumably caused by the low fluid velocity and the build up of high pH gradients across me soil core.
12. The build up of acidic conditions at the anode during the application of the electroosmosis process is due to the oxidation of water. The products of me oxidation are oxygen gas (02) and hydrogen ions (H*-). Inversely, the basic condition at me cathode is attributed to the reduction of water. This electrochemical reaction decomposes me water producing hydrogen gas (Hz) and hydroxyl ions (OH-).
13. The results demonstrated (hat it will be practical to remove the C8 by electro-osmosis process under pH controlled conditions at the influent and effluent zone. A 97 %
45
EID103239
removal of the C8 in the effluent at the cathode was achieved in the test under pH control at the anode (pH = 10) with NaOH/HCL 14. The best practice to obtain high degree C8 removal is to promote high water velocity through die soil core. This can be achieved by maintaining alkaline pH conditions at the electrolyte region. However, it is necessary mat the water flow velocity overcomes the electrical migration of the anionic C8 which moves in an opposite direction to water
flow. 15. The most important physical-chemical property of the soil to affect the electro-osmosis
process is the pHzpc- The electro-osmotic water flow rate is directly proportional to the
pHzyc of the soil particles.
16. Lower efficiency of the electro-osmosis process was observed when Ca(OH)2 or
CaCOs instead of NaOH was used in the pH conditioning at the anode. This
observation can be attributed to the following reasons: a) high pH conditions caused
precipitation of some salts, e.g., CaC03 that coated the surface tftJ(lhe electrodes, yielding low efficiency of the electro-osmosis process; b) By introducing calcium ions
(instead of sodium ions) into the system, the ionic strength increases substantially,
causing a diminishing of the zeta potential (0 and consequenflyyfliie fluid velocity
through the soil towards the cathode.
17. Tests in which Ca(OH)2 and CaCOs were used to control pH showed high C8
concentrations at the anodic solution. In these experiments, the high pH conditions and
low water flow velocity through the soil core contributed to the electrical migration of
the anionic C8 towards the anode.
18. The moisture content effect on the electro-osmotic flow was evaluated. The results
indicate that the moisture content does not significantly affect the time required for the
soil column saturation, but does affect the electro-osmotic flow.
>
--&
u> oo
46
EID103240
V. References
Acar, Y., Gale, R., Putnam, G., Hamed, J. and Wong, R., Electrochemical Processing of Soils: Theory of pH Gradient Development by Diffusion, Migration, and Linear
Convection, J. Env. Sci. Health. A25f6>. 687-714.1990
Arpad K., Handbook of Soil Mechanism, Volume H, Soil Testing, Oxford, NY. 1980.
Brunaouer, S. L., Emmet, P. H. and Teller, E, Adsorption of Gases in Multimolecular
Layers, J. Amer. Chem. Soc.. 60, 309,1938.
Casagrande, L., Electro-osmosis in Soils, Geptechnique. Vol. 1, p. 1959-1977,1949. Chappell, B., and Burton, P., Electro-Osmosis Applied to Unstable Embarkment,
J.Geotech. Eng. Div.. ASCE. 1Q1(8\ 733-740.1975.
Esrig, M. and Majteni, S., A New Equation for Electro-Osmosis flow and Its Implication
for Porous Media, Highway Research Record, No.11, HRB Publication 133L 31-45,
1965.
Fetter, C. W., Applied Hydrogeology, Charles E., Merill Publishing Co., 1980.
Helmholtz, H. von. ami. Phvsik Wiedemanm. 7.337,1879.
Pojasek, J. W., Membrane Ultrafiltration Disposing of Hazardous Chemical Waste, "
Environ, Sci, Tech,,13J7), 810,1979.
;,,
Schmid, G.. Z. Electrochem. 56, 35-81, 1952
Shuckrow, A. J., Pajak, A. P., and Touhil, C. J., Concentration Technology for
Hazardous Aqueous Waste Treatment, EPA-60Q/2-81-019,1981.
Sims, J. T., and Heckendom. S. E., Methods of Soil Analysis, U. of Delaware, College
of Agricultural Sciences, Agricultural Experimental Station, Cooperative Ex-tension,
Newark, DE. 1991. Staas, E. B., Waste Disposal Practices. A Threat to Health and the Nation's Water Supply,
Report to the U.S. Congress, CED-28-120, GAO, June 16,1978. Standard Methods for the Examination of Water and Wastewater, 16th edition, American
Public Health Association, Washington DC, 1985.
47
EID103241
s
Appendix B
Electro-osmosis test II
Physical properties of the soil core
Soil sample: ADPS-2 (0-5') Amount of the specimen placed in the cell: 646.1 g C8 concentration: 33 ug/g dry soil
Amount of dry soil: 595.1 g Water content: 7.9 % Cell volume: 363.2 cm3 (length: 10.0 cm; cross sec. area: 36.32 cm2) Bulk density: 1.64 g/cm3 Particle density: 2.64 g/cm3 Porosity: 0.38
Pore volume: 138.0 cm3
Electrodes: graphite Electrolyte solution: process water (pH = Potential applied: 15.0 V
Potential gradient: 1.5 V/cm
7.1)
;'.:j|u.ClOM :-""
iplled: ^Cr ''
?idieot
'-'u
3
I
i--l 0
0\
EID103242
Appendix C
Electro-osmosis test III
Physical properties of the soil core
Soil sample: ADPS-2 (5-10') Amount of the specimen placed in the cell: 681.Ig C8 concentration: 16 p,g/g dry soil Amount of dry soil*: 576.9 g
Water content: 15.3 %
Oil volume: 363.2 cm3 (length: 10.0 cm; cross sec. area: 36.32 cm2)
Bulk density: 1.59 g/cm3 Particle density: 2.64 g/cm3 Porosity: 0.40 Pore volume: 144.4 cm3
Electrodes: graphite Electrolyte solution: process water (pH =; 7.1) Potential applied: 15.0 V Potential gradient: 1.5 V/cm
^ *Considecableamount of wax - around 215 g - was present in this sample. The paraffin
>
was used to seal the bore column at the moment of the sample collection.
i--
^
0't
EID103243
Appendix D
Electro-osmosis test IV
Physical properties of the soil core
Soil sample: ADPS-2 (0-5')
Amount of the specimen placed in the cell: 693. Ig
:>. ; '^.cw^
0 C8 concentration: 33 H-g/gdry soil Amount of dry soil: 638.4 g
sefr ^ry so
Water content: 7.9 %
Cell volume: 363.2 cm3 (length: 10.0 cm; cross sec. area: 36.32 cm2) Bulk density: 1.76 gfcm3
n; et.
'J
Particle density: 2.64 g/cm3
"r
Porosity: 0.33
Pore volume: 119.9 cm3
Electrodes: graphite
Electrolyte solution: process water (pH= 7.1)
Potential applied: 15.0 V
Alectrr
^,,
Potential gradient' 1.5 V/cm
Controlled pH at the anode with HCl and Na(OH); pH = 10. Controlled pH at the cathode with HCl and NaOH; pH = 10.
^arurf
9
^
s
-"* 0
^
M
EID103244
Appendix E
Electro-osmosis test V Physical properties of the soil core
Soil
sample: ADPS-2 (0-5')
Amount of the specimen placed in the cell: C8 concentration: 33 ug/g dry soil
Amount of dry soil: 624.6 g Water content: 7.9 % Cell volume: 363.2 cm3 (length: 10.0 cm; Bulk density: 1.72 g/cm3 Particle density: 2.64 g/cm3 Porosity: 0.35
Pore volume: 127.1 cm3
678.2 g
cross sec.
area:
36 32
cm2)
Electrodes: graphite
Electrolyte solution: process water
saroiytfr ? :'
Potential applied: 15.0 V
Potential gradient 1.5 V/cm
&' < "^f
Controlled pH at the anode with HC1 and Ca(OH)2; pH = lO.te^ ^
Controlled pH at the cathode with HC1 and NaOH; pH = 10. '
EID103245
Appendix F
Electro-osmosis test VI
Physical properties of the soil core
Soil sample: mixture of ADPS-2 (0-17') and BGMW-6 (0-2') Amount of the specimen placed in the cell: 647.7g
C8 concentration: 67 p-g/g dry soil Amount of dry soil: 641.2 g Water content: 10.1 % Cell volume: 363.2 cm3 (length: 10.0 cm; cross sec. area: 36.32 cm2) Bulk density: 1.76 g/cm3 Particle density: 2.64 g/cm3 Porosity: 0.33 Pore volume: 121.1 cm3
Electrodes: graphite
Electrolyte solution: process water
^ ...s'-a.v.a.'
Potential applied: 15.0V
^
Potential gradient: 1.5 V/cm
.^^ gradient
Controlled pH at the anode with HCl and CaC03;pH= 6. jecfuH ; i
Controlled pH at the cathode with HCl and NaOH; pH = 10. <-^ ,H ,, , *e
,.;, ioue
rrsodc
a
0 --* 0
^
^.
EID103246
Constant head permeameter apparatus
continuous water supply
overflow
Figure 1. Constant head permeameter. hydraulic head. h = 44 cm; soil sample length, L = 11 cm;
Cross sectional area, A = 19.6 cnA Ref: Fetter, C.W. (1980)
EID103247
0
Adsorption System Type A
^
Figure 2a. Adsorption system type A for the adsorption study under no electrical field.
EID103248
3
3
Adsorption System Type B
o
^
o
^
Figure 2b. Adsorption system type B for the adsorption study under electrical field.
-~j
EID103249
y
Adsorption System Type C
3 Figure 2c. Adsorption system type C for the adsorption study under electrical field.
EID103250
a
graphite electrodes
filter paper Nylon mesh
Figure 3. Typical electro-osmosis apparatus.
EID103251
3 *9
graphite electrodes
filter paper Nylon mesh
:"5
Figure 4. Electro-osmosis apparatus for tests under controlled pH conditions.
EID103252
Fe(total)
Mn(H)
wfi K
0
^i--<
0
Na
Mg
Ca 0
U90IOHSV
Analysis of the site groundwater - major cations
10
20
30
40
50
Concentration (ppm)
Rgure 5. Characterization of the site fluid. Major cations.
Co(H) Zn(n) Ni(n) Cd(lD cu(n) pb(n)
Z/,90IOHSV
w1
Analysis of site groundwater - minor cations ;-
Concentration (ppb)
Figure 6. Characterization of the site groundwater.
'"nor cations.
Analysis of the site groundwater - anions
0
a90IOHSV
20
40
60
80
100 120
Concentration (ppm)
Figure 7. Characterization of the site groundwater. Anions.
Ionic distribution of the groundwater.
'^
scale
01 11
2 meq/L
L -< >ti&t;-" "-* -
other catiolIS
^ f
^M^ o
Ca+2 " ':;w^
Na+
1 H2C03
HC03-
Cl-
S042
/ ^
oflieramons
Cations (meq/L)
Amons (meq/L)
Ca^-2
3.2
HCOs-
2.6
Mg+2
1.1
Na+
1.1
Cl-
2.0
S04-2
1.0
K+
0.1
NOs-
9.6 xlO-3
Mn-*-2
3.6x10-2
C03-2
4.0x10-3
"i
Fe (total)
5.8 xlO-3
Cd(n)
3.2 x 10-5
'
NiO")
1.6 xlO-5
Zn(ID
5.2x10-5
Co(ID
3.4 xlO-5
Figure 8. Ionic distribution of the site groundwater.
EID103256
's'y'y-^f^f
Soil composition - ADPS-1
S^OIOHSV
% of conrposition
^
Figure 9a. Cba^cterizationof the scnt'samples. S|i^fcc;omposiadnocnE4^ofADP^l^c|^^^des
Soil composition - ADPS-1
T--'--r
s
I
Q
0
9^90IOHSV
20
40
60
80
% of composition
Figure 9b. Characterizadon of the soil samples. Soil composition analysisofADPS-1 soil samples.
Soil - ADPS-2
^90IOHSV
% composition
y^y Figure lOa. Characterization of the soil samples, Soil composition analysis of ADPS-2 soil samples"(stack bars).
'81
0'-5'
5'-101
g, .10'-15'
s
ft
15'-20'
20'-25> 25'-30>
0
S1901WSV
10
20
.-30
40
50
% composition
Figure lOb. Characterizaji^ilofthe soil samples. Soil compositionanalysisof ADPS-2 soil samples.
T9ZOTaia
Depth (ft)
Uts>><O^boso>Lt0ftt0^Os>Lin----*-**".^Qm^P
4^ls>0<IUttO<iO^^ "" I" 1" 1" I'" I" " I" .' . I" I"
0^0^t^ts>ts>t0i-*>-*^-*^t"s;.>. W
M
-M
^
.W
^
<
\^l
0'-5'
5'-10<
a Krt-11 5Ct
15'-20'
W-25'
25'-30' 0
0890IOHSV
pH - ADPS2
4^5 2
3
6
pH
^^^l&^S^S^iSjS^.of theaaiNinples.
Soil pH of ADFS-2 soil saniples.
Organic matter ~ ADPS1
I89010HSV
1
1.5
Organic matter (%)
Figure 13. Characterization of the soil samples. Organic matter peicentage ofADPS-1 soil samples.
0'-5'
S'-IO"
10'-15'
s
(^ 15'-20'
20t-25' 251-30'
Z890IOHSV
Organic matter - ADPS-2
0.5
Organic matter (%)
Figure 14. Characteriza^m'6Ftli6 soil sam^es. '"^
Organic tnatter percentage of Al^PS-2 son samples.
nr
w
Cation exchange capacity - ADPS-1
o
S890IOHSV
2
4
6
8
CEC (m^/100
^sKife ^
Figure 15a.Ch,
the soil samples.
age capacityof ADPS-1 soil samples.
Cation exchange capacity - ADPS-1
^
t
WOlOHSV
CEC (meq/lOOg^
Figure 15b. Characterizadonofthe soU samples. Exchangeableions of ADPS-1 soil samples (stack bars).
ff-5
5'-10'
g icy-is'
a
^ is'^o'
20t-25'
25'-30t
Cation exchange capacity - ADPS-2
S890IOHSV
Figure l6a. Charact^ri2adonof the soil samples. Effective cadon exchange capacity of ADPS-2 soil samples.
^ ta,
O'-S1
y-w
fi 10'-151
^ 15'-20'
20t-25l
25'f -3-lA0t
Cation exchange capacity - ADPS-2
9890IOHSV
Figure 16b. Characterization of Haesoil sample,
'
Exchangeable ions of ADPS-2 soil samples (stack bars).
Moisture content - ADPS1
o
/.890IOHSV
10
15
Moisture Content (%)
Figure 17. Characterization of the soil samples. Moisture content of ADPS-1 soil samples.
8890IOHSV
Moisture content - ADPS -2
M'
___
_ _ moisture content (%)
Figure 18. e-ha^^l^onof the soU samples.
KI<^^^^itent of ADPS-2 soil sami
n.S^S'S,K^-
689010HSV
Q 1'
0
'
0.05
0
.1
0..1'5'
'
0.2
-
0.25
'
0.
3
'
'
P/P
0
, ^'' -^^^
Rgme 19. Charactenzation of the soil samples. "'
'""
BET plotof ADPS-2 soil sample (depthrange of 0 to 5 feet).
Q
70
-,--,--,--,--,--,--j.
T--,--,--F
'i "" ' r11"
DuPont SoU ADPS2(5'-10')
60 Specific surface area = 21.87 m /g
y=-2.6 + 315x; R=0.997
50
I-S 40 -
6i
:
Q 3 0-:
2 0 T--1 -
0
0
0690IOHSV
J----I----A
0.05
J--------I----I-
1
f
'
0.1 P/P
0
0.15
Figure 20L Characterizadon of the soil samples. BBT plot of ADPS-2 soil sample (depthtange of 5 to 10 feet).
0
I690IOHSV
0.05 0.1 O.f5 0.2 0.25 0.3
P/P
^
.. ::;- ^.1'^" .
Rgure 21. Characterization of the soU samples.
"
'" "" '
BET plot of ADPS-2 son sample (depthrange of 10 to 15 fe
200
150
^ 100
3
^k_j
50
A 1
0
S690IOHSV
... ... I 0.05
.1 . . . . 1 . . . . I . . . . I . .
0.1 0.15 0.2 0.25
P/P-,
tf --.' '
""
*
\
.. .
.
1<'*^. -
*..>...
Rgure 22.
C
h
a
r
a
c
t
e
r
i.z.
a
t
i
o
.
n
..,1(h. e
son
.
samples.
-r...^jr^f^SaS;
.
BET plot of ADPS-2 soil sample (depthrange of 15 to 20 feet).
i.*"
v
0
Q
P
n.^
_ _^
'
^
0 0.05
0.1
.
I .
.
.
.
I
.
I
. .
.1 .
0.15 0.2 0.25 0.3
P/P
0
S690IOHSV
Figure 23. Characterization of the soil samples. BET plot of ADPS-2 soil sample (depthrange of 20 to 25 feet).
Q1
0
0.05 '-- ' '
I
0.1
1
^
1_'
5
'
0.2
'
'
i
.
.
0.25
P/P
0
fr690IOHSV
Figure 24. Characterization of the soil samples. BET plot of ADPS-2 soil sample (depthrange of 25 to 30 feet).
9
0'-5' 5'-10'
10'-15'
a
(S 15'-20'
20',-2^t5ft 25'-3'5A0
E690IOHSV
pHZPCofADPS-2
0
.-^^aa^ ^^ - .-"i ?-
iU 0
-10
g3 -20 -
>sJ*
:
-30 ~
:
-40 -
:
-50 0
9690IOHSV
pHZPCofADPS-2(0-5')
S
1
'
1
'
'
'
1
,,
H
. .-.
!
9
.
.
IslxlO^M .--
" IslxlO^M .
I = 1 x 10'3 M ^vy
2
4
6
8
pH
Figure 26. Characterization of the soil samples.
Detennination of the pHzpc of ADPS-2 soil sample(depArange of 0 to 5 fe
^
\y
9
10
0
-10
g -20
kj1
-30
40
pHZPC of ADPS-2 (5-101)
^--,--,--,--,--,--,--,--,--,--,--,--i--,,--,--', i .'--'--
'
----------^----------------------^------------
^
-" "
- "
1"
i "
: IsSxIO^M
'. " IslxlO^M - IslxlO^M
^
^ .
-50
90IOHSV^
32 46 (
8
-:
PH
Figure 27. Characterization of the soil samples. Determination of the pHzpc of ADPS-2 soil sample (depthrange of 5 to 1 feet). .
H/-
w^
^
ft
-<
s
0
00
^
1 t
-"--s
h
c"^
' .*
s'
6r-l
42
^.
^i--rl^
C<1
1
M
fc
'8
& y
%
.-e -
e
^
\o
'
." ^
"^ '
-
-
fi
^1
i-g go T- m (----1
<SH^ c tit-i
" 1^ ^^^
n L
^ ?
a s
^t
<2w*83
sss -" ^
11
i ^^-
PL|
-
3
^
x
x
--
xn
-<
11 11 11
)--<
i--i
>--<
-
^
00
M
I1
00 00 0
0
<s
(M
^-
vo '
00
'
>
CO
g
o
(AW) 5
0^0\
00
EID103280
^fr^:-^ ^
10
:
0
-10 :
:
-20 -
-30 -
i^1
-40 :
:
-50 :
-fin 1
6690IOHSV
pHZPC ofADPS-2 (15-20')
;\ ! 4 ^ ^i
.
.
*
I^xlO^M . ^ " IslxlO^M I^lxlO^M
2 3 4 pH 678
Figure 29. Characterization of the soil samples. Determination of the pHzpc ofADPS-2 soil sample (depthrange of 15 to feet).
JLV
:
0
-10
^
^
-20
SsJ1
-30
: ^
-40
:
-^n 0
pH ZPC of ADPS-2 (20-25')
-\ %'l.
^
,
^
1=5x10'^
IslxlO^M .
IslxlO^M
2
4
6
8
OMOIOHSV
Rgure 30. Characterization of the soireamples. Determination of the pHzpc of ADPS-2 soil sample(depthrange of 20 to 2
'
feet).
T----i----r----i----|----i----i----r
^ s s
iii^ ^ ^ x
'"4
<1n ?
r-
II
r-
II
EID103283
u
Vertical hydraulic permeability
-ADPS2 (0' - 5')-
ZOZ.OIOHSV
Figure 32. Soil permeabilitymeasurement by constant head penneameter. Soil sample:ADSP2(0'-5').
50 [
Vertical hydraulic permeability
-ADPS2 (5' -10>
T----'--r
hydraulic permeability == 1.6 x 10'6 cm/sec o
40
30
s
^ 20
10
0 0
^OIOHSV
[i:Y, -i----i--L
20
40
60
80
Time (hr)
Figure 33. Soil permeability measurement by constant head permeameter. SoU sample: ADSP2 (5' 10').
'^
Vertical hydraulic permeability
-ADPS2 (15' - 20')-
WOlOHSV
Figure 34. Soil permeability measurement "byconstant head permeameter.
Son sample: ADSP2 (15' - 20').
1
WWe^r 0
SO^OIOHSV
Figure 35. Soil permeabilitymeasurement by constant head pCTmeameter. Son sample:ADSP2 (20* - 25').
. ,
\J
Vertical hydraulic permeability
-ADPS1 (23* - 25')-
.,
I
0
>
90Z,OIOHSV
Figure 36. Soil permeabilitymeasurement byconstant head permeameter. Son sample: ADSP1 (23' 25').
3
EID103289
(Wip^a
S-fi
r 0
s
H21
e.S3
S'
ed OT
S
*--
o
S
00
EID103290
C8 concentration profile - ADPS2
60LOIOHSV
Figme 39. C8 concentration profile in ADPS-2 site.
Adsorption study
Residual C8 concentration vs. pH -ADPS2 (O'-S1)"
OUOIOHSV
Figure 40. Residual C8 concentration as a function of pH. Soil sample: ABl'82 (0'-5'). Experimental conditions: initial C8 concentration = 50 mg/L; soU/water ratio = 0.05 g^mL;ionic strength= 0.1 M NaC104.
.^
0
a&--on5;.
Adsorption study
Residual C8 concentration vs. pH -ADPS2(5t-10')-
T----,----r
H^OIOHSV
Kguie 41. Residual C8 concentration as a function of pH. Soil sample: ADPS2 (5'-10'). Experimentalconditions are the same as in Rgure 40.
-.. us.,
' ,..,,
^szeoTdia
residual C8 concentration (ppm)
^o
ffi
Adsorption study
^
Residual C8 concentradon vs:^E
-ADPS2 (15'-20')-
%
&UOIOHSV
Figure 43. Residual C8 concentration as a function of pH. Soil sample: ADPS2 (15'-20').
Experimental conditions are the same as in Figure 40.
y Adsorption study
Residual C8 concentration vs. pH
^
-ADPS2 (201-25t)-
frUOIOHSV
Figure 44. Residual C8 concentration as a function ofpH. SoU sample: ADPS2 (20'-25'). Experimental conditions are the same as in Figure 40.
z.6ZOTaia
residual C8 concentration (ppm)
TO
a
c
<w
Adsorption kVJfsr.xnm: a,... s,tudi y
Percentage of C8 adsorbed vs. pH -ADPS2 (0'-5')-
9UOIOHSV
Figure 46. Percentageof C8 adsorbed as a function of pH. SoH sample: ADPS2 (0'-51). Experimental conditions: initial C8 concentration = 50 mg/L;
soiVwater ratio s 0.05 g/mL; ionic strength = 0.1 M Nad04.
-,,/
\ff'
Adsorption study
Percentage of the C8 adsorbed vs. pH -ADPS2 (5'-101)-
WlOHSV
Figure 47. Percentageof C8 adsorted as a function of pH. Soil sample: ADPS2 (5'-101). Kcpenmental condidons are the same as in Rgure 46.
^
Adsorption study
^ ^
Percentage of C8 adsorbed vs. pH
-ADPS2 (10t-15t)-
il
?s^>
's-
s
s
0
CO
00 U
^
I4-
SUOIOHSV
Figure 48. t'ercentageofC8 adsorbed as a function ofpH. Son sample; ADPS2 (I0'-15').
Experimental conditions are the same as in Hguie 46.
.^a-----
.
^--^S| /<..^-:-:-:-'-:%,
|^%%S^
u
^
Adsorption study
Percentage of C8 adsorbed vs. pH -ADPS2 (iy-2ffY
^
N^
T3
<D
-e
0
I
oo
U
40-i
I
6UOIOHSV
Figure 49. Percentage of C8 adsorbed as a function of pH. Soa sample: ADPS2 (15'-201). Experimental conditions are the same as in Figure 46.
Q
.J
Adsorption study
Percentage of C8: adsorbed vs. pH
-ADPS2 (20'-25')-
O^OIOHSV
Figure 50. Percentageof C8 adsorbed as a function of pH. Soil sample: ADPS2 (20'.25').
Experimentalconditions are the same as in Figure 46.
0
o
0
Adsorption study
Percentage of C8 adsorbed vs. pH
-ADPS2 (25t-30')-
IZXOIOHSV
Figure 51. PercentageofC8 adsorbed as a function ofpH. Son sample: ADPS2 (25'-301). Experimentalconditions are the same as in Figure 46.
Equilibrium diagram of C8 species C7Pi5COOH---->C7Fi5COO~ + H+ pKa ==2.9
0
Figure 52. Equilbdum diagram ofC8 species. .^
EID103304
i
3
J5
I
s.
I
SO
5 He .a
ZZ,OIOHSV
900iaia
C8 concentration in aqueous phase (ppm)
t-A
1--*
fs.
D
0
L^i
C
1 Ul fcs>
' ' ' 1' ' ' " i ' ' ' " 1' ' " '
4^ - C
(vIHXH
ON
0
51
DO 4^b00\
OP-^py*
g. g3 " .
S*^ w
eft oa
S .
SA
3 '
0
-
^
a
00
0
a
o
)
0
c
10
C^
T--(
/
- .ffiO
S "'"' :-. .K"
-
.
-
?%>^ -do oOwi,
'^--<rl -
t ^ s S^<M
o ^
^5S^&y '^ S s?0 'S&3'SD
^
1
0
n0 ^
<1
^
^ co
^ ^
v-
0
-
^r-<
'^ ^h 00 ^ocs^-
3
^'"j
'3
S
OD^
ji6*
&
3
0
^?i! <--t
si^'aia..
00
hs (
04
S.SS g
ISt g %
s-
"S.'a.S
I'!!
111 TO
S.D -^
"
< U ow-
s^S
CD - ^i-
SHsh<
^or
;
i
B j^i
in
CO
o CO
in
C^
o C^
<^-< no^
n
o
(%) P^qjosop 83 jo :nmourc
3
EID103307
80OT(3ia
C1
'0 s
0
C8 concentration
^
in aqueous phase (ppm)
H^
t--A
o
^
o
t-n
tog 11 1 1 1 J 1 1 | 11 1 1 1 1 | 1 1 1 '1 "1 "1"
t
UNl ' S.S?H
|| i -
(
r" "
^ IS 0S^1s1^"
ON
j ^1 "a.
-a| ffi
tig &1-^
y^ ^
?P 2S-5
g2g;8sg^
QS.?
?
t--
0 5
(W TO"
00
0
<
f^Wy
Oi--3fLcy.
.:.. 7'
..
c
.
'-<'';'
'! 1' ?
-
S '
DOi. .
^ 0-^0 N4^>y0\ 3. &* &* '
s:d. GO CO
'"'
wa
0 D4-
0 D^
0. 0^ ,^oo>3
b & ? vT^3
n)
w
y
B
i a s N>o-0>
^/^o w
0 - o^gY^i
0 w^s
Q^<
o"' w
T
* -
-
t-t r ''" 1 '''*'''' *1 '*''''
-J
'.3 '-,-/' W'-wWasyr , <,,.
,.iilff8( '
.^^..^^ Adsorption/desorption study
S C8 desorbed (%) vs. pH
''2A
a}l
J>U ------------------
-ADPS2 (5'-10')-
';'* '' '*'
ft ; Equilibdum tilme
'
,
^-'--s 25 -
^s^^
:
-e 20 ,
0
w
^ ^3 15
00 u
'g-
-g 10
3 1
5
0 6hrs n 24hrs 48hrs
D 0 :P .
8
.
n o 0
6
*'
'
0
',8, Ito.
^
/OPS2-
'"f
g. s. oaVQ
>^^
i
,
,
2
4
6
8
10
pH
LZLOIOHSV
Figure 55b. The percentageofC8 desorptionfrom ADPS2 (5'. 10') vs. pH.
Expenmental conditions; initial C8 concentration in solid phasea 1.0 tag/ sod/water ratio a 0.05 g/mL; ionic strengths 0.1 M NaCK)4.
oiseoTciia
C
residual C8 concentration (ppm)
W
0
00 ^
0-^
4^
t-ft
U\
0
0
g -
0
CQ
0
--
4^
II"0 1
I
0
0\
0
0
I
0
--
00
ADn0n
> > > 0 0 U ^5 h5 ^d
oa oa CA ls> N> 10
^ \^i- <^^>
>-
^~S
V
/^0^t -
o
i"
1 -* tft
m ^
t-/l
^+X
> > >
0 UU
*"tf *^ '"d
oa l/a w
(^ M (^
/t~S^)
'^^. (s>
^^ -*
u o m
r ' i"
W b0 t0
0 U 0
.
1-X]0+-
^+X
^
"
+'^ >/t^
.-.-..--.-. ~ ;1;TM^:':
04-^ X
oa
^^ 2->
^ %
{U 0
^9
- ^^?-
o g.
0 C
g^ a? &*
-- ^vy
^-^ N-^ .'s~^,,, - -
e
0X4- 0
^ D
--
0
s>
,
>
i
i
>
i
i
>
.
Adsorption stuciy
Soilwat<sr ratio effect at various pH
-ADPS2 (O'^'))-
120
-,----^----,----^..T----,-
^ s/-?s 100
s^
'rt
5
A
*sP 80
85=3
^13 Cw
00 0
60
^ -
:
a
40 -
g
0
ca 20
n
"2
r
;
4 .
.
S'^ Q
4
Soil/water ratio (g/ixiL
!0 0.005 D 0.01 0.05 A 0.1
^ * ^
Q a
A
A
A
8 6 -'
fy^j
6
8
10
pH
6Z/,OIOHSV
Figure 57. The soil water ratio effect on the C8 adsorption. soil sample: ADPS2(0*- 5'). Experimental conditions: initial C8 concentration =
ionic strength = 0.1 M N&C104.
50 mg/L;
ZTEEOTdia
,-
amount of C8 adsorbed (%)
ls>
4^
Os
C ?
0
0
0
^,--i--i--i--i--r-"i--i--|--i--i--r--r '
00
0
0
0
'ii I'-r-i-i^
D
^
D
-
> ~-.
"
-y^...' -':"".'. "'
- '.
.
D
Os -
-
^3
ffi DO
.
CO
003 ^
DO 1;
00
1
^
00 t-*Ul ^
1. y^.' .
0
C
i""t .., II,,,,,.11 ,,,,.,,,,----L--A-
'--'
i
TOTai3
amount of C8 adsorbed (%)
10
C=>
0
4^
0
a0 \
oo
0
to --,--,--(-"""I""11 "". 1 1 1 1 i ' * i C
^
D
D
0\ -
D
^3
ffl
D
00 " DB
9
a'
00
nii 2. w
^*
^
o0o0 5^Vi
v--
m^ S
-
1
1^
^-JL
J^-L
^"'l.is?^
Adsorption study
C8 adsorbed (%) vs. pH
SZ,OIOHSV
Figure 60. Percentage of C8 adsorbed as a function of pH. SoU sample :ADPS2((y- 5'). Experimental conditions: initial C8 concentration = 50 rag/L;
Temperature= 45C; ionic strength= 0.1 M Nad04.
STeeoTdia
amount of C8 adsorbed (%)
r
3 0 0 0 10
4s
CTs
00
c 3
Is^
0
3
C :>
r--T-- |^l -r-a'
0 D1
4^
D
0
GD
1 ^ c.
gg^..
Os -
0
D
^
ffi
0
D
00 -aa
^D
1
L
0' 1p--~
'
D0
^ HH
II 11 11
U^l
^
ls>
Ul 0
>--
>0
0 0 0
<I >
^1 CD Q<
s>g
?
E3 g-
S0 1f^f
S^
8 . . 03
-'^E-
M0 . -
to
1 ...
9i0iaia
residual C8
concentration (ppm)
C
^-A
(.^
^
01
0
^ cD
0
0
C
?h ^yi 'I'll Jj
""i
1^"11
1i i i i 1
D
0
^ ,
0
C
4^ -
0
CT\ -
.
^
ffi
^ K"
&B. c^ &
o '-'
^^ 8 < ""11"
o ^
V w ^k
D
i
'
oa
D ^
^'.... . .
D 0^
1s . ^o"
^
?CD
a
-11
00 ^1
GD^
^
S
11 11
.
SB ^o u!^i
0 - .,,. 0
S'0
.
D0
H
H
^11. f -31- 1.
4^ N) t-^
U Ln ^
0
0
0 0 0
DC
.
CO
[^ - 1- C
to i i i i i i
^.leeoiaia
C8 concentration
c
->
0P; in aqueous phase (ppm)
0
St/^ u\ ^ a
I--A
--*
ts^
C<Q J(gP ' i ' ' ' 0 1 ' ' >
ED
8
I's1!?
-^ -
,,
0 GD
^CI>
0
-^s
'T;?
.
.
'." .1 -'. -go
liil o\
"l-^l
0
D
0
^
^g68
8
S&M2 'T3
S^ST.e-<sS Hw-<
0
D
4
<->
0
(3
.
?^8 Qg:^^ oo Q e-
j
0
S^ *
0
,,
\-/
00
D0
OD^ 8OT
'
H H 1-1
.
000000 8 o - II 11 ^n 4^ (0 i-^ Ln m o
0 i. g C3
ls> --i--i--i--i--I--i--i--i-- . i . . j--j--i--i--i--
50
40
t
l iS f 3 0
-a 5
1^20
1
Adsorption study
Effect of initial C8 concentration
T--'--'--'--i--'
-0-10 ppm
~}-20ppin
-O-SOppin
-A-50 ppm
^
.^"
^ ' > ' ' ' .^X '
^r
. ^11^.-..-<>---<>-----<>"-"0--"0
. ^ / / </ ^o""""'"0"""'""0--"D--D"""--D
f/F
! ff
9Z,OIOHSV
Figure 64. The residual C8 concentration as a function of pH at initial C8 concentration below 50 ppm;
soil sample:ADPS-2(0'-5').
Experimental conditions: ionic strength= 0.1 M NaC104.
6TOTaia
Residual C8 concentration (ppm)
c
w
0
^
'^f
Adsoiption study
Effect of initial C8 concentration
^ Q
\^,
S
'S02
00 U
t4-(
P
^
t3
S^OIOHSV
Figure 66. Percentage of C8 adsorbed as a function of pH at various initial C8 concentration. Soil sample: ADPS2 (0'-51).
Experimental conditions: pH =7.0; ionic strengtha
0.1 M NaC104.
iseeoTdia
C.
Amount of C8 adsorbed (%)
J
^
300 250 200 150 100
Adsorption study
i i Partition'coefficient of C8/soil matrix .vs* pH
"x" 'r1 | ""1" i i | i ""i .' i ' "|" i
| '"i, ""i
0
0 10 ppm D 20 ppm 0 30 ppm A 50 ppm
D
0
50
0 2
O^OIOHSV
^ ^
4
6
8
10
pH
M. ,
-^n r
Figure 68. Partition coefficient of C8 vs. pH at initial concentration below 50 ppm; soU sample: ADPS-2 (0'-5'). Experimentalconditions: Soil/water ratio = ionic strength = O.I M NaC104.
0.05 mg/L;
u
Q
Q
500 400 300
-
n i .l
M m
'';*'.i<- <
^
Adsorption study
pardti|pncoefficient of the C8/soil matnx
A
0 50ppm
0
D 100 pp
0 150 pp D0 A 200 pp
-^ o
r
200fc
l^Z,OIOHSV
^ j . ^
4 '6--J ^^
pH
i?,
10
Figure 69. Partition coefficient ofC8 vs. pH
at initial concentration 50-200 ppm; soil sample; ADPS-2 (0'-5'). Experimental conditions: Soil/water ratio = ionic strength = 0.1 M NaC104.
0.05 mg/L;
u
w
Adsorption smdy finder electrical field
ii ill Effluent pH variation vs. time
| i i l""i | i i 11 | I'ri'i | 111 i |
i
'
a
&
^Z-OIOHSV
Figure 70. The pH of effluent from the continuous flow apparatus. Experimentalconditions: initial C8 concentration s 50 mg/L, ionic strength= 0.1 M, weight of soil = 200 g.
I?
s^
-s
s
0
w
00
U
4-< 0
S
!3
0
^
E^OIOHSV
Adsorption study under electrical field Cumulative C8 retained in the soil vs. Time
50 100 150 200 250 300 350 Time (min)
Figure 71. The amount ofC8 retained in the soil vs. time. Experimentalconditions are the same as in Figure 70.
Adsorption study under electrical field
Effluent volume time vs. "I"""i" i i" i | i i i i | r i i"> | 'i i i i" |
I' ' " I'
0
WOIOHSV
' j"
100
' "
150
' j "
j
200 250
Time (min)
'
1
300
'
350
Figure 72. Effluent volume vs. time. Experimentalconditions are the same as in Figure 70.
/.seeoidia
accumulative flow (mL)
c
ts>
^
00
0
0
0
C
^
0
i I-5s
<< w
<
c
e*!';,
u
u
u
y
Coefficient of eleCtro-osmotic permeability
CO
>
^
^
^
\00
T--l
X
Pt^OIOHSV
time (days)
Hgure 74a. ElectKM>smosis experiments. Coefficient of electro-osmotic penneability (ke)as a function of time for Test
I.nandm.
t
I,,
41-'-s,
11;
u
u
u
u
Coefficient of electro-osmotic permeability
i i" j "i 111ii i i i11 i
CO
> ^^
(^
8.
\0
b
T-^
.X.
Z,W.OIOHSV
time (days)
Figure 74b. Electro-osmosis experiments. Coefficient of electro-osmotic permeability(ke) as a function of time for Tests
IV, V and VI.
OEESOTdia
current density
(x 10-2 mA/cm2)
0
0
c
IQ.
-s ^
w
0
ceeeoTdia
p ainfluent
0
^<
03
P* Hin.f,luent
^ i H iKxSssm
0
0
Q
0
The pH of effluent solution
a
ffi
Ck
0
ISZOIOHSV
10 20 30 y-40 50 60 70 tune (days)
Figune 77a. Electro-osmosis experiments.
Ths pH of effluent solution as a function of time for Tests I, n and ED
w
v
0
The pH of effluent solution
I
a
&
3SZ,OIOHSV
10
15
20
25
time (days)
Figure 77b. Electro-osmosis expiainents.
The pH of effluent solution as a function of time for Tests IV, V and
w
a &
S& g
I
00 U
< ^ ^ ^ ^ ^ ^ feSi^Si-S^
-^
C8 concentration at the effluent
l.j.i, j | | | l j 1 l I I j I I I I j l"T'l 1"[ II I I |'l I
CSLOIOHSV
30 40 50
time (days)
'<. ^
Figure 78. Electro-osmosis experiments. C8 concentration at the effluent solution as a function of time.
v
0
0
/ 0
n an'1'tfc '-is
C8 concentration at the influent
I 'I | "1 I I I'"I'I I 1 I I I | I I I I ) I I I l-^T-I I 1 | I
3
00
0
frSZ,OlOHSV
30 40 50 time (days)
Figure 79. Electro-osmosis experiments. C8 concentration at the influent solution as a function of time.
y
Q
30 r ' ' i i
i
1
0
a 2
oo
0
^
^>
'W
C8 removed at the cathode
i I i i i i | r i"'|"11 'i""i i r r'i
-0-Test I -0-Testn
"-O- Test ffl
--A- Test IV
-^-TestV
Test VI
SSZ,OIOHSV
0
10 20 30 40 50 60 70
time (days)
Figure SOiElectro-osmosis experiments.
Cumulative C8 removed at the cathode (in milligrams) as a function of time
u
u
C8 removed at the cathode
ii111ji i i i -j i i i i i
^
-0
g
0
a
00 U
9S^,OIOHSV
30 40 50 time (days)
Figure SUEIectro-osmosis experiments.
Cumulative C8 removed at the cathode (in percentage) as a function of time
v
0
0
Water content
^
I
c 0
0
I(-1
^
^S^COIOHSV
relative distance, x/L
Figure 82. Electro-osmosis experiments. Water content distribution Vs. relative distance. x: distance to the anode (cm); L: total length of soil column (cm).
0
0
The pH profile across the soil sample
T------j-
%
0^
8S'Z,OIOHSV
0.4
0.6
relative distance, x/L
Figure 83. Electro-osmosis experiments.
The soil pH Vs. relative distance. x: distance to the anode (cm); L: total length of soil column (cm).
w
Q
0
y
Relative C8 concentration remained in the soi
o
U
U
6SZ,OIOHSV
0.4
0.6
relative distance, x/L
Figure 84. Electro-osmosis experiments.
?
Relative C8 concentration measued in the soil Vs. relative distance x: distance to the anode (cm); L: total length of soil column (cm)
^
Q
ij
The effect of moisture content on the electroosmotic
^J^D/U\/
----------------------------------j--,--,--,--i--j--,--i--
; Moisture content =12%
300 l A Moisture content = 1%
^/\/w ;
D
without electricity
250 -
,--s,
:
e
5 200 -
1=5
:
1 ^ 150
4-i <t>
100 :
:
50 -
:
0^)
A AA
S A
n
D
^AnD D n""
50
100
A
o
150
A A
200
Time (hr)
09/,OIOHSV
Figure 85. The effect of moisture content on the electro-osmotic flow. Soil sample: RBLMW2 (10'-12').