Highlights of Mediated Electrochemical Oxidation (MEO)

1. 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

2. Introduction
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 CO2and H2O
Metallic ion constantly undergoing oxidation and reduction
Major byproducts are CO2and H2O
Highlights of Mediated Electrochemical Oxidation (MEO)
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

3. Mediated Electrochemical Oxidation(MEO)
AnodeRegeneration of Ce4+ Ce3+→ Ce4++ e-
Oxidation Reaction
Ce4++ Organics → Ce3++ CO2+ InorganicsOxidationCe4+
Reduction
Ce3+
Organics
Inorganics, CO2
e-
Clean Technology Pilot Laboratory
Sunchon National University

4. 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 CO2generation, 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

5. Experimental
Fig. 1. Schematic of MEO Process Clean Technology Pilot LaboratorySunchon National UniversityMEO SolutionTank
Silyine Pump
Reactor
Pt Electrode
Scrubber
CO2Analyzer
Multi-Meter
N2Cylinder

6. Experimental
Analysis
Estimation of this study
Ce3+/Ce4+redox potential in anolyte solution
Estimating the amount of CO2in the off-gas
Measurement of Ce3+/Ce4+redox potential
-Pt-Ag/AgCl combined electrode
-pH/ORP meter(Orion, model 720A)
Measurement of degradation of Aniline
-CO2analyzer(Environmental Instruments, Anagas CD 95)
C6H7N+12H2O+28Ce(IV)6CO2+27H++NH4+28Ce(III)
Clean Technology Pilot Laboratory
Sunchon National University

7. Results & Discussion
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)
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0 20 40 60 80 100
Reaction Time(min)
Concentration of CO2(ppm)
0
20
40
60
80
100
120
140
Cumulative Volume of CO2(ml)
Clean Technology Pilot Laboratory
Sunchon National University

8. Results & Discussion
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0 20 40 60 80 100
Reaction TIme(min)
Concentration of CO2(ppm)
-50
0
50
100
150
200
250
Cumulative Volume of CO2(ml)
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

9. Results & Discussion
Fig. 4. Evolution of CO2 during the degradation of 600ppm aniline at 90℃
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0 10 20 30 40 50 60 70 80 90 100
Reaction Time(min0
Concentration of CO2(ppm)
0
50
100
150
200
250
Cumulative Volume of
CO2(ml)
CO2 Theory 100% destruction of aniline (600 ppm) 232 ml CO2
EXPRIMENT 98% destruction of aniline (600 ppm) 227 ml CO2
C6H7N + 12 H2O + 28 Ce(IV)  6 CO2 + 27 H+ + NH4 + 28 Ce(III)
Clean Technology Pilot Laboratory
Sunchon National University

10. Results & Discussion
Fig. 5. Redox potential and Ce(IV) concentration under the degradation
of 600ppm aniline at 90℃
1460
1470
1480
1490
1500
1510
1520
0 50 100 150 200
Time, min
Redox Potential,
mV
0.7
0.75
0.8
0.85
0.9
0.95
1
Ce(IV), M
Redox,mV
Ce(IV), M
Ce(IV) Theory 100% destruction of aniline (600 ppm) 0.18 M Ce(IV)
EXPERIMENT 98% destruction of aniline (600 ppm) 0.16 M Ce(IV)
For Theoretical Value for multi-electron coefficient degradation of aniline:
Molar concentration of Ce(IV) / Molar Concentration of Aniline n=28
Clean Technology Pilot Laboratory
Sunchon National University

11. Results & Discussion
0
10
20
30
40
50
60
70
80
90
100
0 30 60 90 120 150 180 210
Reaction Time(min)
Degradation of Aniline(%)
70℃
80℃
90℃
Fig. 6. The degradation of 600ppm aniline at different temperatures
Clean Technology Pilot Laboratory
Sunchon National University

12. Results & Discussion
0
2000
4000
6000
8000
10000
12000
14000
0 10 20 30 40 50 60 70 80 90 100
Reaction Time(min)
Concentration of CO2(ppm)
0
50
100
150
200
250
Cumulative Volume of CO2(ml)
Fig. 7. Evolution of CO2 during the degradation of 1080ppm aniline at 70℃
Clean Technology Pilot Laboratory
Sunchon National University

13. Results & Discussion
0
5000
10000
15000
20000
25000
0 10 20 30 40 50 60 70 80 90 100
Reaction Time(min)
Concentration of CO 2(ppm)
0
50
100
150
200
250
300
350
400
Cumulative Volume of CO 2(ml)
Fig. 8. Evolution of CO2 during the degradation of 1200ppm aniline at 80℃
Clean Technology Pilot Laboratory
Sunchon National University

14. Results & Discussion
Fig. 9. Evolution of CO2 during the degradation of 1200ppm aniline at 90℃
0
5000
10000
15000
20000
25000
30000
0 10 20 30 40 50 60 70 80 90 100
Reaction Time(min)
Concentration of CO2(ppm)
0
50
100
150
200
250
300
350
400
450
500
Cumulative Volume of
CO2(ml)
CO2 Theory 100% destruction of aniline (600 ppm) 464 ml CO2
EXPRIMENT 93% destruction of aniline (600 ppm) 430 ml CO2
C6H7N + 12 H2O + 28 Ce(IV)  6 CO2 + 27 H+ + NH4 + 28 Ce(III)
Clean Technology Pilot Laboratory
Sunchon National University

15. Results & Discussion
Fig. 10 Redox potential and Ce(IV) concentration under the degradation of 1200 ppm aniline
at 90℃
Ce(IV) Theory 100% destruction of aniline (600 ppm) 0.36 M Ce(IV)
EXPERIMENT 98% destruction of aniline (600 ppm) 0.35 M Ce(IV)
For Theoretical Value for multi-electron coefficient degradation of aniline:
Molar concentration of Ce(IV) / Molar Concentration of Aniline n=28
1440
1450
1460
1470
1480
1490
1500
1510
1520
1530
0 50 100 150 200 250
Time, min
Redox, mV
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
Ce(IV), M
Redox,mv
Ce(IV), M
Clean Technology Pilot Laboratory
Sunchon National University

16. Results & Discussion
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250
Reaction Time(min)
Degradation of Aniline(%)
70℃
80℃
90℃
Fig. 11. The degradation of 1200ppm aniline at different temperatures
Clean Technology Pilot Laboratory
Sunchon National University

17. Results & Discussion
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)
2400 ppm Aniline
0
1000
2000
3000
4000
5000
6000
0 20 40 60 80
min
CO2, ppm
CO2,ppm
Temp, deg C
Clean Technology Pilot Laboratory
Sunchon National University

18. Results & Discussion
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 )
Aniline 1200 ppm 90 deg C
0
500
1000
1500
2000
2500
3000
3500
0 20 40 60 80
min
CO2, ppm
CO2,ppm
Temp, deg C
Clean Technology Pilot Laboratory
Sunchon National University

19. Results & Discussion
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
Aniline 2400 ppm
1440
1460
1480
1500
1520
1540
1560
0 20 40 60 80
min
Redox Potential, mv
R/O 1, mv
R/O 2, mv
R/O 3, mv
Clean Technology Pilot Laboratory
Sunchon National University

20. Results & Discussion
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
Aniline 1200 ppm 90 deg c
1450
1460
1470
1480
1490
1500
1510
1520
1530
1540
0 20 40 60 80
min
Redox Potential, mv
R/O 1, mv
R/O 2, mv
R/O 3, mv
Clean Technology Pilot Laboratory
Sunchon National University

21. 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

22. Acknowledgements
This work was funded by “Core Environmental Technology Development
Project for Next Generation”(Eco-Technopia-21) of “Korea Institute of
Environmental Science and Technology”.
Clean Technology Pilot Laboratory
Sunchon National University