Bobrov presentation ce4+ 2005

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

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

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



Mediated Electrochemical Oxidation(MEO)

Anode

Regeneration of Ce4+

Ce3+ → Ce4+ + e-

Oxidation Reaction

Ce4+ + Organics → Ce3+ + CO2 + Inorganics

Oxidation

Ce4+

Reduction

Ce3+

Organics

Inorganics,

CO2

e-



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



Experimental

Fig. 1. Schematic of MEO Process



MEO Solution

Tank

Silyine Pump

Reactor

Pt Electrode

ScrubberCO2 Analyzer

Multi-Meter

N2 Cylinder

Experimental

Analysis

Estimation of this study

Ce3+/Ce4+ redox potential in anolyte solution

Estimating the amount of CO2 in 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

- CO2 analyzer(Environmental Instruments, Anagas CD 95)

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



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)

Co

ncen

tra

tio

n o

f C

O2(p

pm

)

0

20

40

60

80

100

120

140

Cu

mu

lati

ve V

olu

me o

f C

O 2(m

l)




0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 20 40 60 80 100

Reaction TIme(min)

Co

ncen

tra

tio

n o

f C

O2(p

pm

)

-50

0

50

100

150

200

250

Cu

mu

lati

ve V

olu

me o

f C

O2(m

l)

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)




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

Co

nce

ntr

ati

on

of

CO

2(p

pm

)

0

50

100

150

200

250

Cu

mu

lati

ve

Vo

lum

e o

f

CO

2(m

l)

CO2 Theory 100% destruction of aniline (600 ppm) 232 ml CO2

EXPRIMENT 98% destruction of aniline (600 ppm) 227 ml CO2





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

Red

ox

Po

ten

tia

l,

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




0

10

20

30

40

50

60

70

80

90

100

0 30 60 90 120 150 180 210

Reaction Time(min)

Deg

ra

da

tio

n o

f A

nil

ine(%

)

70℃

80℃

90℃

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




0

2000

4000

6000

8000

10000

12000

14000

0 10 20 30 40 50 60 70 80 90 100

Reaction Time(min)

Co

nce

ntr

ati

on

of

CO

2(p

pm

)

0

50

100

150

200

250

Cu

mu

lati

ve

Vo

lum

e o

f C

O2(m

l)





0

5000

10000

15000

20000

25000

0 10 20 30 40 50 60 70 80 90 100

Reaction Time(min)

Co

nce

ntr

ati

on

of

CO

2(p

pm

)

0

50

100

150

200

250

300

350

400

Cu

mu

lati

ve

Vo

lum

e o

f C

O2(m

l)






0

5000

10000

15000

20000

25000

30000

0 10 20 30 40 50 60 70 80 90 100

Reaction Time(min)

Co

nce

ntr

ati

on

of

CO

2(p

pm

)

0

50

100

150

200

250

300

350

400

450

500

Cu

mu

lati

ve

Vo

lum

e o

f

CO

2(m

l)

CO2 Theory 100% destruction of aniline (600 ppm) 464 ml CO2

EXPRIMENT 93% destruction of aniline (600 ppm) 430 ml CO2





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

Red

ox

, m

V

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

Ce(I

V),

M

Redox,mv

Ce(IV), M




0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250

Reaction Time(min)

Deg

rad

ati

on

of

An

ilin

e(%

)

70℃

80℃

90℃

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




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

CO

2,

pp

m

CO2,ppm

Temp, deg C




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

CO

2, p

pm

CO2,ppm

Temp, deg C




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

Re

do

x P

ote

nti

al,

mv R/O 1, mv

R/O 2, mv

R/O 3, mv




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

Re

do

x P

ote

ntia

l, m

v

R/O 1, mv

R/O 2, mv

R/O 3, mv



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.



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”.



Bobrov presentation ce4+ 2005

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