principle investigator: c. p. huang co-investigator: daniel cha
DESCRIPTION
Electrochemical Processes for In-situ Treatment of Contaminated Soils. Principle Investigator: C. P. Huang Co-Investigator: Daniel Cha Graduate Research Assistants: Jih-Hsing Chang Zhimin Qiang Menghau Sung Louis Cheng University of Delaware, Newark, DE 19716. - PowerPoint PPT PresentationTRANSCRIPT
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Principle Investigator: C. P. Huang
Co-Investigator: Daniel Cha
Graduate Research Assistants: Jih-Hsing Chang
Zhimin Qiang
Menghau Sung
Louis Cheng
University of Delaware, Newark, DE 19716
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I. INTRODUCTION
Typical contaminants in DOE soils include PCE, TCE, CHCl3, CCl4, PAHs and heavy metals such as Cu(II), Pb(II), As(V), Cr(VI), and Zn(II).
Effective in-situ remediation technologies are urgently needed.
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II. OBJECTIVES
To develop electrochemical processes for the in-situ treatment of contaminated soils.
To study the mobilization of selected organics from soils by the electro-kinetic (EK) process.
To study the oxidation of selected organics by the electro-Fenton process.
To understand the mechanisms of the oxidation of selected organics by the electro-Fenton process.
4
P
NaOH HClO4 FeSO4
Compressed Oxygen
Cathode Anode
Contaminated Soil
Water Flow
Discharge
Recycle
III. CONCEPTUAL DESIGN OF INTEGRATED ELECTROCHEMICAL PROCESS
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Soil Sample a A B C D E F
Sand (%) 9 23 22 18 14 22Silt (%) 46 36 37 36 38 47Clay (%) 45 41 41 46 48 31pH 6.10 7.46 7.58 7.60 7.60 7.52ECEC (meq/100g) 14.7 21.2 21.2 21.2 20.5 13.8Organic Matter(%) 1.81 0.97 0.82 1.07 0.79 1.17Moisture (%) 16.9 12.4 11.1 12.7 13.6 10.2Hydraulic Conductivity (10-8cm/s) 9.52 38.8 1.72 48.4 2.49 11.7
C2Cl4 in Soil (mg/kg) b ND ND 137 173 ND 9.8
Zeta potential (mV) -14.7 -17.6 -26.3 -32.8 -35.1 -22.8pHzpc 2.60 2.46 2.48 2.20 2.34 2.18
Hydraulic Permeability(10-7cm2) 9.71 39.6 1.76 49.4 2.54 12.0
Specific Surface Area (m2/g) 0.9 0.7 0.4 0.6 0.4 0.5
a: A ( SB009, depth 2'~4' ) D ( SB010, depth 8'~10' ) B ( SB009, depth 9'~11' ) E ( SB011, depth 4'~6' ) C ( SB010, depth 4'~6' ) F ( SB011, depth 12'~14' )
b: Extraction Method: 2g soil + 8mL hexane + 2mL H2SO4(1N) ND: not detectable
IVA.1. Physical-chemical Characteristics of Soil Samples
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Soil Sample A B C D E F
Aniline +Hexachloroethane +++
Pentachlorobutadiene +++
Hexachlorobutadiene +++
Tetrachloroethylene +++ +++ ++
Decane +++
Tetracosane ++
Undecane + +++
+++: relatively high concentration A ( SB009, depth 2'~4' ) D ( SB010, depth 8'~10' ) ++: intermediate concentration B ( SB009, depth 9'~11' ) E ( SB011, depth 4'~6' ) +: relatively low concentration C ( SB010, depth 4'~6' ) F ( SB011, depth 12'~14')
IVA.2. Organic Compounds in Soil Samples
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Soil Sam ple A B C D E FLea dex ch an gea ble 5 1.8 4 5.2 4 5.2 4 5.2 4 5.2 4 5.2sorbed 4 3.1 4 3.1 4 3.1 4 3.1 4 3.1 4 3.1orga nic 7 5.4 8 6.2 7 5.4 8 6.2 7 5.4 7 5.4carbon ate 4 3.1 3 2.3 3 2.3 4 3.1 4 3.1 4 3.1su lfid e 2 5.9 2 5.9 2 5.9 3 2.3 2 5.9 3 2.3C op perex ch an gea ble 1 3.5 1 2.4 1 2.4 1 2.4 1 2.4 1 1 .2sorbed 1 0.9 1 0.9 9.0 1 0.9 1 0.9 1 0.9orga nic 2 2.6 2 4.5 1 2.9 3.2 N D N Dcarbon ate N D N D 1.3 1.3 1.3 1.3su lfid e 1 0.0 1 1 .2 8.9 1 0.0 1 1 .2 1 0.0C a dmi umex ch an gea ble 5.1 5.4 3.8 3.0 2.7 1.9sorbed 2.6 1.9 1.9 1.3 2.6 1.3orga nic 8.4 7.8 5.8 1.3 N D N Dcarbon ate N D N D N D N D N D N Dsu lfid e N D N D N D N D N D N DZ incex ch an gea ble 3.3 3.3 3.3 3.0 3.0 2.7sorbed 2.3 2.3 1.7 1.7 1.7 1.7orga nic 5.1 6.2 4.5 4.5 4.5 4.5carbon ate 1.1 2.3 1.1 0.6 1.1 1.7su lfid e 2.0 2.7 1.7 2.0 2.4 2.4
N ote : concen trat ion s in m g/K g N D: n ot det ec ta ble
IVA.3. Heavy Metal Fractionation in Soil Samples
IVB.1. Adsorption of PCE
Experimental conditions:
– p H = 7
– Ionic strength = 0.05 M (NaClO4)
– Cs = 150 mg/L
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
1:51:101:201:501:100
q e(10
3 µg/g
)
Ce/C
s
IVB.2. Adsorption of TCE
Experimental conditions:
– p H = 7
– I = 0.05 M (NaClO4)
– Cs = 1100 mg/L
0
0.5
1.0
1.5
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
1:51:101:201:501:100
q e(10
4 µg/g
)
Ce/C
s
IVB.3. Adsorption of Naphthalene
Experimental conditions:– p H = 7
– I = 0.05 M (NaClO4)
– Cs = 30 mg/L
– Co-solvent to water (v) ratio= 1:4
0
50
100
150
200
250
300
350
400
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
1:51:101:20
y = 8.6753 + 482.35x R= 0.99666 y = 1.3287 + 492.39x R= 0.99595 y = 9.9933 + 371.11x R= 0.99102
q e (µg/
g)
Ce/C
s
IVB.4. Adsorption of Naphthalene
Experimental conditions:– p H = 7
– I = 0.05 M (NaClO4)
– Cs = 30 mg/L
– Co-solvent to water (v) ratio= 3:2– Soil to solution ratio (w) =
varying
0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
0 0.1 0.2 0.3 0.4 0.5 0.6
1:51:101:20
q e(10
3 µg/g
)
Ce/C
s
IVB.5. Adsorption of Chlorophenols (Adsorption Isotherms)
Experimental conditions:
– p H = 4
– I = 0.05 M (NaNO3)
– C0 = varying
0
0.5
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4 5 6 7
4-ClPh2,4-ClPh
2,4,5-ClPh
q e (µ
mol
e/g)
[Chlophenol] (mM)
IVB.6. Adsorption of Chlorophenols (Effect of pH)
Experimental conditions:– p H = varying
– I = 0.05 M (NaNO3)
0
0.5
1
1.5
2
2.5
4 6 8 10 12
4-ClPh2,4-ClPh2,4,5-ClPh
q e (µm
ole/
g)
pH
IVC.1. Electrochemical Generation of Hydrogen Peroxide (Setup)
O2 N2
pH CONTROL
pH METER
FLOW METERS
HCl NaOH
TEMPERATURE CONTROL SYSTEM
DC POWER SUPPLY
THERMOMETER
pH PROBE
ACIDPUMP
BASEPUMP
IVC.2. Electrochemical Generation of Hydrogen Peroxide (current intensity)
Experimental conditions:– p H = 2
– I = 0.05 M (NaClO4)
– O2 = 2000 cc/min (pipe diffuser)
– T = 25 oC– Cathode Area =754 cm2
2
4
6
8
10
12
14
0 0.2 0.4 0.6 0.8 1 1.2 1.4
@ 15 min
@ 30 min
0 0.265 0.53 0.795 1.06 1.325 1.59 1.855
H2O
2 Con
cent
ratio
n (p
pm)
Current Intensity, I (Amp)
Current Density, i (10-3 Amp/cm2)
IVC.3. Electrochemical Generation of Hydrogen Peroxide (pH)
Experimental conditions:– p H = varying
– I = 0.05 M (NaClO4)
– O2 = 2000 cc/min (100%, pipe diffuser)
– T = 25 oC– Cathode Area =754 cm2
– Current Intensity = 1 Amp 0
20
40
60
80
100
120
140
160
1 2 3 4
@ 30 min@ 1 hour@ 2 hours@ 3 hours
H2O
2 Con
cent
ratio
n (p
pm)
pH
IVC.4. Electrochemical Generation of Hydrogen Peroxide (oxygen)
Experimental conditions:– p H = 3
– I = 0.05 M (NaClO4)
– O2 = 2000 cc/min (stone diffuser)
– T = 25 oC– Cathode Area = 754 cm2
– Current Intensity = 1 Amp0
50
100
150
200
250
300
0 50 100 150 200
23% O2
50% O2
100% O2
H2O
2 Con
cent
ratio
n (p
pm)
Time (min)
IVC.5. Electrochemical Generation of Hydrogen Peroxide (temperature)
Experimental conditions:– p H = 3
– I = 0.05 M (NaClO4)
– O2 = 2000 cc/min (100%, pipe diffuser)
– T = varying– Cathode Area = 754 cm2
– Current Intensity = 1 Amp 0
50
100
150
200
250
10 15 20 25 30 35 40 45 50
30 min60 min90 min120 min
H2O
2 Con
cent
ratio
n (p
pm)
Temperature ( oC)
IVC.6. Electrochemical Generation of Hydrogen Peroxide (cathode surface area)
Experimental conditions:– p H = 3
– I = 0.05 M (NaClO4)
– O2 = 2000 cc/min (100%, pipe diffuser)
– T = 25 oC– Cathode Area = varying– Current Intensity = 1 Amp
0
50
100
150
200
250
300
40 50 60 70 80 90 100 110 120
@ 30 min@ 60 min@ 90 min@ 120 min@ 180 min
258 323 387 452 516 581 645 710 774
H2O
2 Con
cent
ratio
n (p
pm)
Surface Area of the Cathode (in 2)
Surface Area of the Cathode (cm2)
IVC.7. Electrochemical Generation of Hydrogen Peroxide Peroxide (current efficiency- H2O2 yield)
Experimental conditions:– p H = 3
– I = 0.05 M (NaClO4)
– O2 = 2000 cc/min (100%, stone diffuser)
– T = 25 oC– Cathode Area = 754 cm2
– Current Intensity = 1 Amp0
20
40
60
80
100
0
50
100
150
200
250
300
0 50 100 150 200
Efficiency (%)
[H2O2] (ppm)
Eff
icie
ncy
(%)
H2 O
2 Concentration (ppm
)
Time (min)
IVD.1. Electrokinetics (setup)
anodereservoir
cathodereservoirsoil sample
graphite electrodes Nylon meshfilter paper
power supply
A
V
electrolytesolution
effluent
IVD.2. Electrokinetics (mono-chlorophenols)
Experimental conditions:
– p H = not controlled
– Electrolyte = 10-3 M (NaCl)
– Applied voltage = 12 v
– T = 25 oC
– Time = 15 days
– Electrode distance = 10 cm
0.0
0.5
1.0
1.5
2.0
0 0.2 0.4 0.6 0.8 1
ph2Clph3Clph4Clph
normalized distance from anode
IVD.3. Electrokinetics (di-Chlorophenol)
Experimental conditions:– p H = 6– Electrolyte = 10-3 M (NaCl)– Applied voltage = 12 v – T = 25 oC– Time = varying– Electrode distance = 10
cm
0
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.6 0.8 1
2-day treatment 5-day treatment10-day treatment15-day treatment
C/C
0
normalized distance from anode
IVE.1. Fenton Oxidation (setup)
NaOH HClO4
1
2
6
7
5
1. pH Controller2. Reactor3. Stir Bar4. pH Meter5. Sample Port6. Stir Plate7. Thermostat8. Thermometer9. Dosage Pump
3
81% H2O2
4
9
IVE.2. Fenton Oxidation (PCE, batch mode)
Experimental conditions:
– p H = 3
– I = 5 x10-2M (NaClO4)
– H2O2 = 2 x10-3 M
– T = 25 oC
– FeSO4 = varying
– C0 = 50 ppm
0
20
40
60
80
100
0 1 2 3 4 5
BlankFe2+ =5x10 -4 MFe2+ =1x10 -3 MFe2+ =1.5x10-3 M
Res
idua
l %
Time (min)
IVE.3. Fenton Oxidation (TCE, batch mode)
Experimental conditions:– p H = 3
– I = 5 x10-2M (NaClO4)
– H2O2 = varying
– T = 25 oC
– FeSO4 = 3x10-3 M
– C0 = 100 ppm
0
20
40
60
80
100
0 1 2 3 4 5
BlankH
2O
2=5x10 -4 M
H2O
2=1x10 -3 M
H2O
2=2x10 -3 M
H2O
2=4x10 -3 M
Res
idua
l %
Time (min)
IVE.4. Fenton Oxidation (naphthalene, batch mode)
Experimental conditions:– p H = 3
– I = 5 x10-2M (NaClO4)
– H2O2 = varying
– T = 25 oC
– FeSO4 = 1x10-3 M
– C0 = 25ppm
0
20
40
60
80
100
0 1 2 3 4 5
BlankH
2O
2=5x10-4 M
H2O
2=1x10-3 M
H2O
2=2x10-3 M
Res
idua
l %
Time (min)
IVE.5. Fenton Oxidation (continuous mode)
Experimental conditions:
– p H = 3
– I = 5 x10-2M (NaClO4)
– H2O2 = 3.4 x10-4 M/min
– T = 25 oC
– FeSO4 = 1x 10-3 M (naphthalene), 1.5 x10-3 M (PCE), 3x10-3 M(TCE)
– C0 = naphthalene:25 ppm; PCE = 50 ppm; TCE = 100ppm.
0
20
40
60
80
100
0 2 4 6 8 10
PCETCE
Naphthalene
Res
idua
l %
Time (min)