Principle Investigator: C. P. Huang Co-Investigator: Daniel Cha

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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.

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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


– 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


– 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)


– 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)


– 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)


– 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)


– I = 0.05 M (NaClO4)


– 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)


– I = 0.05 M (NaClO4)


– 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)


– 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)


– 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

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IVE.2. Fenton Oxidation (PCE, batch mode)


– 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)


– 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)


– 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)


– 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)

Principle Investigator: C. P. Huang Co-Investigator: Daniel Cha

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Transcript of Principle Investigator: C. P. Huang Co-Investigator: Daniel Cha