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
140
8000
120
7000
100
6000 5000
80
4000
60
3000
40
2000
20
1000 0
Cumulative Volume of CO2 (ml)
Concentration of CO2 (ppm)
Results & Discussion
0 0
20
40
60
80
100
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
250 200
7000 6000
150
5000 100 4000 3000
50
2000 0
Cumulative Volume of CO2(ml)
Concentration of CO2(ppm)
8000
1000 0
-50 0
20
40 60 Reaction TIme(min)
80
100
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
10 20 30 40 50 60 70 80 90 100 Reaction Time(min0
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
150
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℃
20
80℃
10
90℃
0 0
30
60
90
120
150
180
210
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)
12000 200 10000 150
8000 6000
100
4000 50 2000 0 0
10
20
30
40
50
60
70
80
90
Cumulative Volume of CO 2 (ml)
14000
0 100
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
400
Concentration of CO 2(ppm)
20000 300 250
15000
200 10000
150 100
5000
Cumulative Volume of CO 2(ml)
350
50 0
0 0
10
20
30
40
50
60
70
80
90
100
Reaction Time(min)
Fig. 8. Evolution of CO2 during the degradation of 1200ppm aniline at 80℃
Clean Technology Pilot Laboratory
Sunchon National University
30000
500 450 400 350 300 250 200 150 100 50 0
25000 20000 15000 10000 5000 0 0
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
1520
0.95
Redox,mv Ce(IV), M
1510
0.9 0.85
1490 0.8 1480
Ce(IV), M
Redox, mV
1500
0.75 1470 0.7
1460
0.65
1450 1440 0
50
100
150
200
0.6 250
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
50
100 150 Reaction Time(min)
200
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
60
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