Mediated Electrochemical Oxidation(MEO)

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Degradation of aniline by mediated electrochemical. Oxidation (MEO) process. Vladimir Bobrov ... Metallic ion constantly undergoing oxidation and reduction.
Sunchon National University

Degradation of aniline by mediated electrochemical Oxidation (MEO) process

Vladimir Bobrov, Sang Joon Chung, S. Balaji & Il Shik Moon* (Dept. of Chemical Engineering, Sunchon National University)

Clean Technology Pilot Laboratory

Sunchon National University

Introduction  Highlights of Mediated Electrochemical Oxidation (MEO)  Offers attractive route for the destruction of organic pollutants

 Metallic ion in the oxidized form in an acid acts as a mediator  Mediator ion will oxidize organic pollutants into CO2 and H2O  Metallic ion constantly undergoing oxidation and reduction

 Major byproducts are CO2 and H2O

 Aniline as Target Organic Pollutant  Aniline is a major by-product in petro-chemical and coal-tar industries  Aniline will polymerize into more toxic poly aniline if not removed Clean Technology Pilot Laboratory

Sunchon National University

 Mediated Electrochemical Oxidation(MEO)

e-

Regeneration of Ce4+

Ce3+ → Ce4+ + e-

Oxidation Ce4+

Oxidation Reaction Ce4+ + Organics → Ce3+ + CO2 + Inorganics

Reduction Ce3+ Anode

Clean Technology Pilot Laboratory

Organics

Inorganics, CO2

Sunchon National University

Object of this study • To Apply MEO Technology to Analyze the Destruction of High Concentrations of Aniline, under different solution temperatures

• To evaluate the pattern of redox potential and CO2 generation, during the destruction of aniline • To compare the theoretical and experimental values of Ce(IV) requirement for aniline destruction

Clean Technology Pilot Laboratory

Sunchon National University

Experimental Scrubber

CO2 Analyzer

Silyine Pump

Pt Electrode N2 Cylinder

MEO Solution Tank

Reactor Multi-Meter

Fig. 1. Schematic of MEO Process Clean Technology Pilot Laboratory

Sunchon National University

Experimental  Estimation of this study  Ce3+/Ce4+ redox potential in anolyte solution  Estimating the amount of CO2 in the off-gas C6H7N + 12 H2O + 28 Ce(IV)  6 CO2 + 27 H+ + NH4 + 28 Ce(III)

 Analysis  Measurement of Ce3+/Ce4+ redox potential - Pt-Ag/AgCl combined electrode - pH/ORP meter(Orion, model 720A)  Measurement of degradation of Aniline - CO2 analyzer(Environmental Instruments, Anagas CD 95)

Clean Technology Pilot Laboratory

Sunchon National University

9000

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Cumulative Volume of CO2 (ml)

Concentration of CO2 (ppm)

Results & Discussion

0 0

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Reaction Time(min)

Fig. 2. Evolution of CO2 during the degradation of 600ppm aniline at 70℃ (Theoretical Total Volume of CO2 for Complete degradation of Aniline = 232 ml)

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion 9000

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Cumulative Volume of CO2(ml)

Concentration of CO2(ppm)

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Fig. 3. Evolution of CO2 during the degradation of 600ppm aniline at 80℃ (Theoretical Total Volume of CO2 for Complete degradation of Aniline = 232 ml) Clean Technology Pilot Laboratory

Sunchon National University

18000 16000 14000 12000 10000 8000 6000 4000 2000 0

250 200 150 100 50

Cumulative Volume of CO2(ml)

Concentration of CO2(ppm)

Results & Discussion

0 0

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Fig. 4. Evolution of CO2 during the degradation of 600ppm aniline at 90℃

C6H7N + 12 H2O + 28 Ce(IV)  6 CO2 + 27 H+ + NH4 + 28 Ce(III) CO2

Theory

100% destruction of aniline (600 ppm)

232 ml CO2

EXPRIMENT

98%

227 ml CO2

Clean Technology Pilot Laboratory

destruction of aniline (600 ppm)

Sunchon National University

Redox Potential, mV

1520 1510 1500 1490 1480 1470 1460

1 0.95 0.9 0.85 0.8 0.75 0.7

Redox,mV Ce(IV), M

0

50

100

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Ce(IV), M

Results & Discussion

200

Time, min Fig. 5. Redox potential and Ce(IV) concentration under the degradation of 600ppm aniline at 90℃ For Theoretical Value for multi-electron coefficient degradation of aniline: Molar concentration of Ce(IV) / Molar Concentration of Aniline n=28 Ce(IV)

Theory

100% destruction of aniline (600 ppm)

0.18 M Ce(IV)

EXPERIMENT

98%

0.16 M Ce(IV)

Clean Technology Pilot Laboratory

destruction of aniline (600 ppm)

Sunchon National University

Results & Discussion 100

Degradation of Aniline(%)

90 80 70 60 50 40 30

70℃

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80℃

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90℃

0 0

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Reaction Time(min)

Fig. 6. The degradation of 600ppm aniline at different temperatures

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion 250

Concentration of CO 2 (ppm)

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Reaction Time(min)

Fig. 7. Evolution of CO2 during the degradation of 1080ppm aniline at 70℃

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion 25000

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Fig. 8. Evolution of CO2 during the degradation of 1200ppm aniline at 80℃

Clean Technology Pilot Laboratory

Sunchon National University

30000

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Cumulative Volume of CO2(ml)

Concentration of CO2(ppm)

Results & Discussion

10 20 30 40 50 60 70 80 90 100 Reaction Time(min)

Fig. 9. Evolution of CO2 during the degradation of 1200ppm aniline at 90℃

C6H7N + 12 H2O + 28 Ce(IV)  6 CO2 + 27 H+ + NH4 + 28 Ce(III) CO2

Theory

100% destruction of aniline (600 ppm)

464 ml CO2

EXPRIMENT

93%

430 ml CO2

Clean Technology Pilot Laboratory

destruction of aniline (600 ppm)

Sunchon National University

Results & Discussion 1530

1

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0.95

Redox,mv Ce(IV), M

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0.9 0.85

1490 0.8 1480

Ce(IV), M

Redox, mV

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Time, min

Fig. 10 Redox potential and Ce(IV) concentration under the degradation of 1200 ppm aniline at 90℃

For Theoretical Value for multi-electron coefficient degradation of aniline: Molar concentration of Ce(IV) / Molar Concentration of Aniline n=28 Ce(IV)

Theory

100% destruction of aniline (600 ppm)

0.36 M Ce(IV)

EXPERIMENT

98%

0.35 M Ce(IV)

Clean Technology Pilot Laboratory

destruction of aniline (600 ppm)

Sunchon National University

Results & Discussion 100 90

Degradation of Aniline(%)

80 70 60 50 40 30 20

70℃ 80℃

10

90℃

0 0

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100 150 Reaction Time(min)

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250

Fig. 11. The degradation of 1200ppm aniline at different temperatures

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion 2400 ppm Aniline

6000

CO2, ppm

5000 4000 CO2,ppm Temp, deg C

3000 2000 1000 0 0

20

40 min

60

80

Fig. 12. The degradation of 2400 aniline at temperature 90℃ in flow reactor. (Flow Rate of MEO solution = 2 ml/min, flow Aniline solution = 10 ml/h, volume of reactor = 120 ml)

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion Aniline 1200 ppm 90 deg C

3500

CO2, ppm

3000 2500 2000

CO2,ppm

1500

Temp, deg C

1000 500 0 0

20

40 min

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80

Fig. 13. The degradation of 1200 aniline at temperature 90℃ in flow reactor. (Flow MEO solution = 2 ml/min, flow Aniline solution = 5 ml/h, volume of reactor = 120 ml )

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion Aniline 2400 ppm

Redox Potential, m v

1560 R/ O 1, mv R/ O 2, mv R/ O 3, mv

1540 1520 1500 1480 1460 1440 0

20

40 min

60

80

Fig. 14. Redox Potential by means of three Pt mini-electrodes on distance 13 cm, 24 cm and 35 cm from the basis of a reactor

Clean Technology Pilot Laboratory

Sunchon National University

Results & Discussion

Redox Potential, mv

Aniline 1200 ppm 90 deg c

1540 1530 1520 1510 1500 1490 1480 1470 1460 1450

R/ O 1, mv R/ O 2, mv R/ O 3, mv

0

20

40

60

80

min Fig. 15. Redox Potential by means of three Pt mini-electrodes on distance 13 cm, 24 cm and 35 cm from the basis of a reactor

Clean Technology Pilot Laboratory

Sunchon National University

Conclusions  It is measured of kinetics of destruction of aniline by using MEO technique with Ce(IV) (aniline 1200 ppm and 600 ppm and temperature 70, 80, 90℃).  It is established that at temperature of 90℃ destruction of aniline was found to be more than 90%.  The results obtained from the redox potential and moles of Ce(IV), testify in favor of the mechanism of destruction aniline with multi-electron coefficient n=28.

Clean Technology Pilot Laboratory

Sunchon National University

Acknowledgements

This work was funded by “Core Environmental Technology Developme Project for Next Generation”(Eco-Technopia-21) of “Korea Institute of Environmental Science and Technology”.

Clean Technology Pilot Laboratory