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Removal of H2S in air by corona discharge undercontinuous flow conditionTo cite this article Hyun-Woo Park et al 2013 J Phys Conf Ser 441 012004

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Removal of H2S in air by corona discharge under continuous

flow condition

Hyun-Woo Park Chung Hyun Lee and Dong-Wha Park

Department of Chemical Engineering and RIC-ETTP(Regional Innovation Center for

Environmental Technology of Thermal Plasma) Inha University 253 Yonghyun-dong

Nam-gu Incheon 402-751 Republic of Korea

E-mail dwparkinhaackr

Abstract Hydrogen sulfide (H2S) gas diluted in air was removed on a large scale using a

newly developed wet electrostatic precipitator (Wet-EP) system under the continuous flow

condition at atmospheric pressure and room temperature Acid H2S is spontaneously

neutralized by NaOH and KOH used as basic materials at room temperature And then the

solid salts generated from neutralization reaction were removed by the electrostatic

precipitation method using corona discharge The experimental variables are reaction ratio

between H2S and basic materials reaction time and plasma input power for the removal of

generated solid salts The purpose of this work is to determine optimal operating conditions

and space velocity The removal efficiencies of H2S and dust were over 99 at H2S initial

concentration of 600 ppm and the total flow rate of 2 m3min The optimal space velocities for

NaOH and KOH are almost from 12000 to 15000 hr-1

at reaction time of 006 and 0048

seconds respectively In conclusion KOH is more efficient than NaOH for removal of H2S

1 Introduction

Hydrogen sulfide (H2S) is one of the odor substances that cause air pollution The major emission

sources of H2S gas are biogas production process naphtha process landfills sewage treatment process

food waste treatment process and coal gasification process Human beings have a variety of symptoms

such as mental stress psychological insecurity petulance hysteria hyposmia headache vomit and

insomnia because of odor substances [1] Conventional methods for odor control including wet

scrubbing thermal oxidation catalyst adsorption active carbon ozone oxidation and biofiltration are

limitative technically and economically for the abatment of low concentration odor substances [2-8]

In recent years studies of H2S treatment using various plasma systems such as dielectric barrier

discharge microwave radio frequency pulsed corona discharge gliding arc have been progressed [9-

12] These methods however have problems in large-capacity treatment In this experiment a novel

wet electrostatic precipitator system (Wet-EP) was used to treat H2S on a large scale The Wet-EP

system is the combination of two methods which are wet scrubbing for the neutralization reaction of

H2S with basic materials and electrostatic precipitation by corona discharge for the removal of

generated solid salts An ultrasonic atomizer was used for the injection of basic material solutions in

order to increase the reaction surface area The purpose of this work is the confirmation of optimal

conditions to remove large amount of H2S under continuous flow conditions As variables the reaction

ratio of H2S with basic materials reaction time in reaction region and the plasma input power of

electrostatic precipitator were controlled

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

Content from this work may be used under the terms of the Creative Commons Attribution 30 licence Any further distributionof this work must maintain attribution to the author(s) and the title of the work journal citation and DOI

Published under licence by IOP Publishing Ltd 1

2 Experimental setup

Figure 1 The schematic diagram of the Wet-EP

system to remove diluted H2S gas in air

Figure 1 shows the schematic diagram of the Wet-ESP system for the removal of dilute H2S gas in

air The flow rate of H2S was controlled by a mass flow controller (MFC Sierra INC USA) and it

was mixed with air at the exit of ultrasonic atomizer at 600 ppm The total gas flow rate of H2S-air

mixture was controlled by a blower A DC power supply (Plasmatech Co Ltd Korea) which has high

voltage and low current was employed for corona discharge This system consists of two step process

The first step is the spontaneous neutralization reaction of H2S with basic material solutions The

second step is the electrostatic precipitation process of generated salts and water mists by corona

discharge Gas phase H2S and liquid phase basic materials spontaneously reacted in chemical reaction

region at room temperature and atmospheric pressure Therefore solid phase salts and non-reacted

basic material solutions were existed in air These are charged to negative by corona discharge so that

negatively charged liquid and solid salts are precipitated at anode The chemical reaction region was

designated in a plastic pipe line with the inner diameter of 0047 m and the length of 52 m before

electrostatic precipitator The type of electrostatic precipitator electrodes are pin-to-plate with the

electrodes gap distance of 0024 m A cathode is composed of 256 stainless steel pins An anode is

cylindrical plate which is 035 m in length and 0308 m2 in area respectively The inlet and outlet

concentrations of H2S were measured by a flue gas analyzer (MK 9000 RBR Co Ltd Germany)

Amount of dust with and without the operation of the electrostatic precipitator was analyzed using a

dust analyzer (3442 KANOMAX Co Ltd Japan) to evaluate the removal efficiencies of H2S and

dusts Removal efficiencies of H2S and dusts were calculated as follow equations

100()2

in

outinSH

C

CC (1)

100)(

()

atmoff

onatmoff

dustmm

mmm (2)

where ηH2S and ηdust () are the removal efficiencies of H2S and dust respectively Cin and Cout (ppm)

are the inlet and outlet concentration of H2S mon and moff (mgm3) are dust amount before and after the

operation of the electrostatic precipitator matm (mgm3) is dust amount at atmosphere Amount of dust

at atmosphere was 0155 mgm3 The reaction ratio (R) of H2S and basic materials was calculated as

follow equation

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

2

w

b

m

mR

(3)

where b (molmin) and w (molmin) are input molar flow rates of basic materials and H2S gas

respectively In order to evaluate the economic feasibility in each operating conditions the space

velocity (SV) was calculated as follow equation

tRSV

SH

2

36)hr( 1

(4)

where SV (hr-1

) is space velocity value in chemical reaction region t (hr) is reaction time of gas at

reaction region Table 1 indicates the experimental conditions The range of reaction ratio was from

024 to 498 and reaction time was varied from 001 to 006 second The input power of electrostatic

precipitator was controlled from 1 to 180 W Total gas flow rate and initial concentration of H2S were

fixed at 2 m3min and 600 ppm respectively As basic materials NaOH and KOH were used for the

neutralization reaction of H2S

Table 1 Experiment conditions for the removal of H2S by using Wet-EP system

Total flow rate (m3min) 2

Initial H2S concentration (ppm) 600

Type of basic materials NaOH KOH

Reaction ratio 024 ndash 498

Reaction time (sec) 001 - 006

Plasma input power (W) 1 - 180

Input voltage (kV) 12 - 22

Input current (mA) 01 - 85

3 Results and discussion

Figure 2 shows the Gibbrsquos free energy for the neutralization reaction of H2S with basic materials

calculated by thermodynamic equilibrium calculation software (FactSage CRCT amp GTT-technologies

Canada amp Germany) Gibbs free energies for all neutralization reactions have negative value at whole

temperature range as shown in figure 2 Therefore it can be occurred to spontaneous neutralization

reaction at room temperature and atmospheric pressure Since ∆G value for neutralization reaction by

KOH solution is lower than the reaction by NaOH solution the reaction between H2S and KOH is

expected to proceed at easier The major products in the reaction by KOH and NaOH solution are

expected to be solid salts such as Na2S Na2S2 and K2S

Figure 3 presents correlation between the removal efficiency of H2S and the reaction ratio When

H2S is reacted with KOH solution removal efficiency is higher compared with NaOH solution These

results are in a good agreement with calculation results on Gibbs free energies in figure 2 consequently

neutralization of H2S is more favorable to use KOH than NaOH In addition the removal efficiencies

are increased rapidly with increasing the reaction ratio When the reaction ratio is 498 removal

efficiency with KOH basic material is over 99

Figure 4 is calculation results on the space velocity The space velocity has the opposite tendency

with removal efficiency according to the reaction ratio At the reaction ratio of 498 the space

velocities for NaOH and KOH were approximately 11700 and 12000 hr-1

respectively H2S removal

efficiency by KOH was higher than by NaOH at all range of reaction ratio in figure 3 because ∆G

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

3

value of reaction by KOH was lower than by NaOH at room temperature in figure 2 Due to these

results reaction by KOH was more progressed easily than reaction by NaOH

Figure 2 Gibbrsquos free energy calculation result of

neutralization reaction of H2S and basic materials

H2S removal efficiency was confirmed at fixed reaction ratio and controlled the reaction time in the

reaction region Figure 5 shows the removal efficiency of H2S according to the reaction time Length

of plastic pipe line was adjusted in order to control the reaction time The reaction time was varied

from 001 to 006 second at the fixed reaction ratio of NaOH and KOH with 498 Although the

removal efficiency with NaOH is sharply decreased as decreasing the reaction time it with KOH is

gradually decreased as decreasing the reaction time Therefore it is revealed that KOH has faster

neutralization reaction rate and higher chemical activity than NaOH

Figure 6 shows the space velocity according to the reaction time The difference of space velocity

between NaOH and KOH cases is reduced with increasing the reaction time On the other hands the

difference of space velocity by NaOH and KOH is reduced increasing the reaction time The reason is

that the difference of H2S removal efficiency by NaOH and KOH is decreased due to sufficient

reaction time The space velocities for NaOH and KOH were about 11700 and 14900 hr-1

at the

reaction time of 006 and 0048 seconds respectively Therefore KOH is more effective than NaOH

for neutralization of H2S

Figure 3 Removal efficiency of H2S according

to the reaction ratio variation

Figure 4 Space velocity calculation results

according to the reaction ratio variation

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

4

Since large amount of solid salts un-reacted solution and water mists were generated by

neutralization reaction of H2S with basic materials the electrostatic precipitator was used to remove

them Figure 7 indicates the removal efficiency of dust according to the plasma input power which

was varied from 1 to 180 W Dust was mostly removed above 30 W The removal efficiencies are

fairly similar each other in figures 7 (a) and (b) for NaOH and KOH respectively Amount of

exhausted dust was 0180 mgm3 at the input power of 180 W after electrostatic precipitation by

corona discharge in both cases It is very similar with the dust content in atmosphere of 0155 mgm3

Because the amount of exhausted dust without the electrostatic precipitation was over than 140 mgm3

the removal efficiencies of dust were over 99 when the input power exceeded 40 W Therefore large

amount of H2S gas and dust can be removed simultaneously at room temperature and atmospheric

pressure under continuous flow condition using the Wet-EP system

Figure 7 Removal efficiencies of dust according to the plasma input power

with (a) NaOH and (b) KOH solutions

4 Conclusion

A large amount of H2S gas diluted in air was removed in the Wet-EP system by neutralization

reaction and electrostatic precipitation under continuous flow condition NaOH and KOH were used

for neutralization reaction with H2S gas and they were spontaneously reacted at room temperature and

atmospheric pressure The removal efficiency of H2S was 99 at the highest reaction ratio of 498

The KOH reacts with H2S more effectively than NaOH due to relatively low Gibbs free energy For

Figure 5 Removal efficiency of H2S

according to the reaction time

Figure 6 Space velocity calculation results

according to the reaction time

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

5

high removal efficiency optimal conditions of H2S removal reaction by NaOH and KOH were

reaction ratio of 498 in both cases reaction time of 006 and 0048 seconds respectively Under these

conditions the values of space velocity by NaOH and KOH were 11700 and 14900 hr-1

The input

power of plasma was required about 40 W in order to remove dusts completely In conclusion H2S

contained contaminant of 2 m3min can be efficiently removed by using the low power of 40 W in

Wet-EP system

Acknowledgments

This work was supported by the Regional Innovation Center for Environmental Technology of

Thermal Plasma (ETTP) at Inha University designated by MKE (2013)

References

[1] SS Shiffman EA Sattely Miller MS Suggs and BG Graham 1995 Brain Res Bulletin 37

369-375

[2] W H Cheng M S Chou W S Lee and B J Huang 2002 J Env Eng 128 313-320

[3] Y I Matatov-Meytal and M Sheintuch 1997 Ind Eng Chem Res 36 4374-4380

[4] Z H Huang F Kang Y P Zheng J B Yang and K M Liang 2002 Adsorp Sci amp Tech 20

495-500

[5] S W Baek J R Kim and S K Ihm 2004 CatalToday 93 575-571

[6] A H Wani R M R Branion and A K Lau 1997 J Env Sci Health A32 2027-2055

[7] J Ruan W Li Y Shi Y Nie X Wang and T Tan 2005 Chemosphere 59 327-333

[8] I Traus and H Suhr 1992 Plasma Chemistry and Plasma Processing 12 275-285

[9] Zhao Gui-Bing 2007 Chem Eng Sci 72 2216-2227

[10] E Krasheninnkov V D Rusanov S V Sanyuk and A A Fridman 1986 Zh Tekh Fiz 56

1104-1109

[11] T Nunnally K Gutsol A Rabinovich A Fridman A Starikovsky A Gutsol and RW Potter

2009 Inter J Hydro Ener 34 7618-7625

[12] S John JC Hamann SS Muknahallipatna S Legowski JF Ackerman and MD Argyle

2009 Chem Eng Sci 64 4826-4834

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

6

2 Experimental setup

Figure 1 The schematic diagram of the Wet-EP

system to remove diluted H2S gas in air

Figure 1 shows the schematic diagram of the Wet-ESP system for the removal of dilute H2S gas in

air The flow rate of H2S was controlled by a mass flow controller (MFC Sierra INC USA) and it

was mixed with air at the exit of ultrasonic atomizer at 600 ppm The total gas flow rate of H2S-air

mixture was controlled by a blower A DC power supply (Plasmatech Co Ltd Korea) which has high

voltage and low current was employed for corona discharge This system consists of two step process

The first step is the spontaneous neutralization reaction of H2S with basic material solutions The

second step is the electrostatic precipitation process of generated salts and water mists by corona

discharge Gas phase H2S and liquid phase basic materials spontaneously reacted in chemical reaction

region at room temperature and atmospheric pressure Therefore solid phase salts and non-reacted

basic material solutions were existed in air These are charged to negative by corona discharge so that

negatively charged liquid and solid salts are precipitated at anode The chemical reaction region was

designated in a plastic pipe line with the inner diameter of 0047 m and the length of 52 m before

electrostatic precipitator The type of electrostatic precipitator electrodes are pin-to-plate with the

electrodes gap distance of 0024 m A cathode is composed of 256 stainless steel pins An anode is

cylindrical plate which is 035 m in length and 0308 m2 in area respectively The inlet and outlet

concentrations of H2S were measured by a flue gas analyzer (MK 9000 RBR Co Ltd Germany)

Amount of dust with and without the operation of the electrostatic precipitator was analyzed using a

dust analyzer (3442 KANOMAX Co Ltd Japan) to evaluate the removal efficiencies of H2S and

dusts Removal efficiencies of H2S and dusts were calculated as follow equations

100()2

in

outinSH

C

CC (1)

100)(

()

atmoff

onatmoff

dustmm

mmm (2)

where ηH2S and ηdust () are the removal efficiencies of H2S and dust respectively Cin and Cout (ppm)

are the inlet and outlet concentration of H2S mon and moff (mgm3) are dust amount before and after the

operation of the electrostatic precipitator matm (mgm3) is dust amount at atmosphere Amount of dust

at atmosphere was 0155 mgm3 The reaction ratio (R) of H2S and basic materials was calculated as

follow equation

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

2

w

b

m

mR

(3)

where b (molmin) and w (molmin) are input molar flow rates of basic materials and H2S gas

respectively In order to evaluate the economic feasibility in each operating conditions the space

velocity (SV) was calculated as follow equation

tRSV

SH

2

36)hr( 1

(4)

where SV (hr-1

) is space velocity value in chemical reaction region t (hr) is reaction time of gas at

reaction region Table 1 indicates the experimental conditions The range of reaction ratio was from

024 to 498 and reaction time was varied from 001 to 006 second The input power of electrostatic

precipitator was controlled from 1 to 180 W Total gas flow rate and initial concentration of H2S were

fixed at 2 m3min and 600 ppm respectively As basic materials NaOH and KOH were used for the

neutralization reaction of H2S

Table 1 Experiment conditions for the removal of H2S by using Wet-EP system

Total flow rate (m3min) 2

Initial H2S concentration (ppm) 600

Type of basic materials NaOH KOH

Reaction ratio 024 ndash 498

Reaction time (sec) 001 - 006

Plasma input power (W) 1 - 180

Input voltage (kV) 12 - 22

Input current (mA) 01 - 85

3 Results and discussion

Figure 2 shows the Gibbrsquos free energy for the neutralization reaction of H2S with basic materials

calculated by thermodynamic equilibrium calculation software (FactSage CRCT amp GTT-technologies

Canada amp Germany) Gibbs free energies for all neutralization reactions have negative value at whole

temperature range as shown in figure 2 Therefore it can be occurred to spontaneous neutralization

reaction at room temperature and atmospheric pressure Since ∆G value for neutralization reaction by

KOH solution is lower than the reaction by NaOH solution the reaction between H2S and KOH is

expected to proceed at easier The major products in the reaction by KOH and NaOH solution are

expected to be solid salts such as Na2S Na2S2 and K2S

Figure 3 presents correlation between the removal efficiency of H2S and the reaction ratio When

H2S is reacted with KOH solution removal efficiency is higher compared with NaOH solution These

results are in a good agreement with calculation results on Gibbs free energies in figure 2 consequently

neutralization of H2S is more favorable to use KOH than NaOH In addition the removal efficiencies

are increased rapidly with increasing the reaction ratio When the reaction ratio is 498 removal

efficiency with KOH basic material is over 99

Figure 4 is calculation results on the space velocity The space velocity has the opposite tendency

with removal efficiency according to the reaction ratio At the reaction ratio of 498 the space

velocities for NaOH and KOH were approximately 11700 and 12000 hr-1

respectively H2S removal

efficiency by KOH was higher than by NaOH at all range of reaction ratio in figure 3 because ∆G

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

3

value of reaction by KOH was lower than by NaOH at room temperature in figure 2 Due to these

results reaction by KOH was more progressed easily than reaction by NaOH

Figure 2 Gibbrsquos free energy calculation result of

neutralization reaction of H2S and basic materials

H2S removal efficiency was confirmed at fixed reaction ratio and controlled the reaction time in the

reaction region Figure 5 shows the removal efficiency of H2S according to the reaction time Length

of plastic pipe line was adjusted in order to control the reaction time The reaction time was varied

from 001 to 006 second at the fixed reaction ratio of NaOH and KOH with 498 Although the

removal efficiency with NaOH is sharply decreased as decreasing the reaction time it with KOH is

gradually decreased as decreasing the reaction time Therefore it is revealed that KOH has faster

neutralization reaction rate and higher chemical activity than NaOH

Figure 6 shows the space velocity according to the reaction time The difference of space velocity

between NaOH and KOH cases is reduced with increasing the reaction time On the other hands the

difference of space velocity by NaOH and KOH is reduced increasing the reaction time The reason is

that the difference of H2S removal efficiency by NaOH and KOH is decreased due to sufficient

reaction time The space velocities for NaOH and KOH were about 11700 and 14900 hr-1

at the

reaction time of 006 and 0048 seconds respectively Therefore KOH is more effective than NaOH

for neutralization of H2S

Figure 3 Removal efficiency of H2S according

to the reaction ratio variation

Figure 4 Space velocity calculation results

according to the reaction ratio variation

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

4

Since large amount of solid salts un-reacted solution and water mists were generated by

neutralization reaction of H2S with basic materials the electrostatic precipitator was used to remove

them Figure 7 indicates the removal efficiency of dust according to the plasma input power which

was varied from 1 to 180 W Dust was mostly removed above 30 W The removal efficiencies are

fairly similar each other in figures 7 (a) and (b) for NaOH and KOH respectively Amount of

exhausted dust was 0180 mgm3 at the input power of 180 W after electrostatic precipitation by

corona discharge in both cases It is very similar with the dust content in atmosphere of 0155 mgm3

Because the amount of exhausted dust without the electrostatic precipitation was over than 140 mgm3

the removal efficiencies of dust were over 99 when the input power exceeded 40 W Therefore large

amount of H2S gas and dust can be removed simultaneously at room temperature and atmospheric

pressure under continuous flow condition using the Wet-EP system

Figure 7 Removal efficiencies of dust according to the plasma input power

with (a) NaOH and (b) KOH solutions

4 Conclusion

A large amount of H2S gas diluted in air was removed in the Wet-EP system by neutralization

reaction and electrostatic precipitation under continuous flow condition NaOH and KOH were used

for neutralization reaction with H2S gas and they were spontaneously reacted at room temperature and

atmospheric pressure The removal efficiency of H2S was 99 at the highest reaction ratio of 498

The KOH reacts with H2S more effectively than NaOH due to relatively low Gibbs free energy For

Figure 5 Removal efficiency of H2S

according to the reaction time

Figure 6 Space velocity calculation results

according to the reaction time

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

5

high removal efficiency optimal conditions of H2S removal reaction by NaOH and KOH were

reaction ratio of 498 in both cases reaction time of 006 and 0048 seconds respectively Under these

conditions the values of space velocity by NaOH and KOH were 11700 and 14900 hr-1

The input

power of plasma was required about 40 W in order to remove dusts completely In conclusion H2S

contained contaminant of 2 m3min can be efficiently removed by using the low power of 40 W in

Wet-EP system

Acknowledgments

This work was supported by the Regional Innovation Center for Environmental Technology of

Thermal Plasma (ETTP) at Inha University designated by MKE (2013)

References

[1] SS Shiffman EA Sattely Miller MS Suggs and BG Graham 1995 Brain Res Bulletin 37

369-375

[2] W H Cheng M S Chou W S Lee and B J Huang 2002 J Env Eng 128 313-320

[3] Y I Matatov-Meytal and M Sheintuch 1997 Ind Eng Chem Res 36 4374-4380

[4] Z H Huang F Kang Y P Zheng J B Yang and K M Liang 2002 Adsorp Sci amp Tech 20

495-500

[5] S W Baek J R Kim and S K Ihm 2004 CatalToday 93 575-571

[6] A H Wani R M R Branion and A K Lau 1997 J Env Sci Health A32 2027-2055

[7] J Ruan W Li Y Shi Y Nie X Wang and T Tan 2005 Chemosphere 59 327-333

[8] I Traus and H Suhr 1992 Plasma Chemistry and Plasma Processing 12 275-285

[9] Zhao Gui-Bing 2007 Chem Eng Sci 72 2216-2227

[10] E Krasheninnkov V D Rusanov S V Sanyuk and A A Fridman 1986 Zh Tekh Fiz 56

1104-1109

[11] T Nunnally K Gutsol A Rabinovich A Fridman A Starikovsky A Gutsol and RW Potter

2009 Inter J Hydro Ener 34 7618-7625

[12] S John JC Hamann SS Muknahallipatna S Legowski JF Ackerman and MD Argyle

2009 Chem Eng Sci 64 4826-4834

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

6

w

b

m

mR

(3)

where b (molmin) and w (molmin) are input molar flow rates of basic materials and H2S gas

respectively In order to evaluate the economic feasibility in each operating conditions the space

velocity (SV) was calculated as follow equation

tRSV

SH

2

36)hr( 1

(4)

where SV (hr-1

) is space velocity value in chemical reaction region t (hr) is reaction time of gas at

reaction region Table 1 indicates the experimental conditions The range of reaction ratio was from

024 to 498 and reaction time was varied from 001 to 006 second The input power of electrostatic

precipitator was controlled from 1 to 180 W Total gas flow rate and initial concentration of H2S were

fixed at 2 m3min and 600 ppm respectively As basic materials NaOH and KOH were used for the

neutralization reaction of H2S

Table 1 Experiment conditions for the removal of H2S by using Wet-EP system

Total flow rate (m3min) 2

Initial H2S concentration (ppm) 600

Type of basic materials NaOH KOH

Reaction ratio 024 ndash 498

Reaction time (sec) 001 - 006

Plasma input power (W) 1 - 180

Input voltage (kV) 12 - 22

Input current (mA) 01 - 85

3 Results and discussion

Figure 2 shows the Gibbrsquos free energy for the neutralization reaction of H2S with basic materials

calculated by thermodynamic equilibrium calculation software (FactSage CRCT amp GTT-technologies

Canada amp Germany) Gibbs free energies for all neutralization reactions have negative value at whole

temperature range as shown in figure 2 Therefore it can be occurred to spontaneous neutralization

reaction at room temperature and atmospheric pressure Since ∆G value for neutralization reaction by

KOH solution is lower than the reaction by NaOH solution the reaction between H2S and KOH is

expected to proceed at easier The major products in the reaction by KOH and NaOH solution are

expected to be solid salts such as Na2S Na2S2 and K2S

Figure 3 presents correlation between the removal efficiency of H2S and the reaction ratio When

H2S is reacted with KOH solution removal efficiency is higher compared with NaOH solution These

results are in a good agreement with calculation results on Gibbs free energies in figure 2 consequently

neutralization of H2S is more favorable to use KOH than NaOH In addition the removal efficiencies

are increased rapidly with increasing the reaction ratio When the reaction ratio is 498 removal

efficiency with KOH basic material is over 99

Figure 4 is calculation results on the space velocity The space velocity has the opposite tendency

with removal efficiency according to the reaction ratio At the reaction ratio of 498 the space

velocities for NaOH and KOH were approximately 11700 and 12000 hr-1

respectively H2S removal

efficiency by KOH was higher than by NaOH at all range of reaction ratio in figure 3 because ∆G

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

3

value of reaction by KOH was lower than by NaOH at room temperature in figure 2 Due to these

results reaction by KOH was more progressed easily than reaction by NaOH

Figure 2 Gibbrsquos free energy calculation result of

neutralization reaction of H2S and basic materials

H2S removal efficiency was confirmed at fixed reaction ratio and controlled the reaction time in the

reaction region Figure 5 shows the removal efficiency of H2S according to the reaction time Length

of plastic pipe line was adjusted in order to control the reaction time The reaction time was varied

from 001 to 006 second at the fixed reaction ratio of NaOH and KOH with 498 Although the

removal efficiency with NaOH is sharply decreased as decreasing the reaction time it with KOH is

gradually decreased as decreasing the reaction time Therefore it is revealed that KOH has faster

neutralization reaction rate and higher chemical activity than NaOH

Figure 6 shows the space velocity according to the reaction time The difference of space velocity

between NaOH and KOH cases is reduced with increasing the reaction time On the other hands the

difference of space velocity by NaOH and KOH is reduced increasing the reaction time The reason is

that the difference of H2S removal efficiency by NaOH and KOH is decreased due to sufficient

reaction time The space velocities for NaOH and KOH were about 11700 and 14900 hr-1

at the

reaction time of 006 and 0048 seconds respectively Therefore KOH is more effective than NaOH

for neutralization of H2S

Figure 3 Removal efficiency of H2S according

to the reaction ratio variation

Figure 4 Space velocity calculation results

according to the reaction ratio variation

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

4

Since large amount of solid salts un-reacted solution and water mists were generated by

neutralization reaction of H2S with basic materials the electrostatic precipitator was used to remove

them Figure 7 indicates the removal efficiency of dust according to the plasma input power which

was varied from 1 to 180 W Dust was mostly removed above 30 W The removal efficiencies are

fairly similar each other in figures 7 (a) and (b) for NaOH and KOH respectively Amount of

exhausted dust was 0180 mgm3 at the input power of 180 W after electrostatic precipitation by

corona discharge in both cases It is very similar with the dust content in atmosphere of 0155 mgm3

Because the amount of exhausted dust without the electrostatic precipitation was over than 140 mgm3

the removal efficiencies of dust were over 99 when the input power exceeded 40 W Therefore large

amount of H2S gas and dust can be removed simultaneously at room temperature and atmospheric

pressure under continuous flow condition using the Wet-EP system

Figure 7 Removal efficiencies of dust according to the plasma input power

with (a) NaOH and (b) KOH solutions

4 Conclusion

A large amount of H2S gas diluted in air was removed in the Wet-EP system by neutralization

reaction and electrostatic precipitation under continuous flow condition NaOH and KOH were used

for neutralization reaction with H2S gas and they were spontaneously reacted at room temperature and

atmospheric pressure The removal efficiency of H2S was 99 at the highest reaction ratio of 498

The KOH reacts with H2S more effectively than NaOH due to relatively low Gibbs free energy For

Figure 5 Removal efficiency of H2S

according to the reaction time

Figure 6 Space velocity calculation results

according to the reaction time

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

5

high removal efficiency optimal conditions of H2S removal reaction by NaOH and KOH were

reaction ratio of 498 in both cases reaction time of 006 and 0048 seconds respectively Under these

conditions the values of space velocity by NaOH and KOH were 11700 and 14900 hr-1

The input

power of plasma was required about 40 W in order to remove dusts completely In conclusion H2S

contained contaminant of 2 m3min can be efficiently removed by using the low power of 40 W in

Wet-EP system

Acknowledgments

This work was supported by the Regional Innovation Center for Environmental Technology of

Thermal Plasma (ETTP) at Inha University designated by MKE (2013)

References

[1] SS Shiffman EA Sattely Miller MS Suggs and BG Graham 1995 Brain Res Bulletin 37

369-375

[2] W H Cheng M S Chou W S Lee and B J Huang 2002 J Env Eng 128 313-320

[3] Y I Matatov-Meytal and M Sheintuch 1997 Ind Eng Chem Res 36 4374-4380

[4] Z H Huang F Kang Y P Zheng J B Yang and K M Liang 2002 Adsorp Sci amp Tech 20

495-500

[5] S W Baek J R Kim and S K Ihm 2004 CatalToday 93 575-571

[6] A H Wani R M R Branion and A K Lau 1997 J Env Sci Health A32 2027-2055

[7] J Ruan W Li Y Shi Y Nie X Wang and T Tan 2005 Chemosphere 59 327-333

[8] I Traus and H Suhr 1992 Plasma Chemistry and Plasma Processing 12 275-285

[9] Zhao Gui-Bing 2007 Chem Eng Sci 72 2216-2227

[10] E Krasheninnkov V D Rusanov S V Sanyuk and A A Fridman 1986 Zh Tekh Fiz 56

1104-1109

[11] T Nunnally K Gutsol A Rabinovich A Fridman A Starikovsky A Gutsol and RW Potter

2009 Inter J Hydro Ener 34 7618-7625

[12] S John JC Hamann SS Muknahallipatna S Legowski JF Ackerman and MD Argyle

2009 Chem Eng Sci 64 4826-4834

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

6

value of reaction by KOH was lower than by NaOH at room temperature in figure 2 Due to these

results reaction by KOH was more progressed easily than reaction by NaOH

Figure 2 Gibbrsquos free energy calculation result of

neutralization reaction of H2S and basic materials

H2S removal efficiency was confirmed at fixed reaction ratio and controlled the reaction time in the

reaction region Figure 5 shows the removal efficiency of H2S according to the reaction time Length

of plastic pipe line was adjusted in order to control the reaction time The reaction time was varied

from 001 to 006 second at the fixed reaction ratio of NaOH and KOH with 498 Although the

removal efficiency with NaOH is sharply decreased as decreasing the reaction time it with KOH is

gradually decreased as decreasing the reaction time Therefore it is revealed that KOH has faster

neutralization reaction rate and higher chemical activity than NaOH

Figure 6 shows the space velocity according to the reaction time The difference of space velocity

between NaOH and KOH cases is reduced with increasing the reaction time On the other hands the

difference of space velocity by NaOH and KOH is reduced increasing the reaction time The reason is

that the difference of H2S removal efficiency by NaOH and KOH is decreased due to sufficient

reaction time The space velocities for NaOH and KOH were about 11700 and 14900 hr-1

at the

reaction time of 006 and 0048 seconds respectively Therefore KOH is more effective than NaOH

for neutralization of H2S

Figure 3 Removal efficiency of H2S according

to the reaction ratio variation

Figure 4 Space velocity calculation results

according to the reaction ratio variation

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

4

Since large amount of solid salts un-reacted solution and water mists were generated by

neutralization reaction of H2S with basic materials the electrostatic precipitator was used to remove

them Figure 7 indicates the removal efficiency of dust according to the plasma input power which

was varied from 1 to 180 W Dust was mostly removed above 30 W The removal efficiencies are

fairly similar each other in figures 7 (a) and (b) for NaOH and KOH respectively Amount of

exhausted dust was 0180 mgm3 at the input power of 180 W after electrostatic precipitation by

corona discharge in both cases It is very similar with the dust content in atmosphere of 0155 mgm3

Because the amount of exhausted dust without the electrostatic precipitation was over than 140 mgm3

the removal efficiencies of dust were over 99 when the input power exceeded 40 W Therefore large

amount of H2S gas and dust can be removed simultaneously at room temperature and atmospheric

pressure under continuous flow condition using the Wet-EP system

Figure 7 Removal efficiencies of dust according to the plasma input power

with (a) NaOH and (b) KOH solutions

4 Conclusion

A large amount of H2S gas diluted in air was removed in the Wet-EP system by neutralization

reaction and electrostatic precipitation under continuous flow condition NaOH and KOH were used

for neutralization reaction with H2S gas and they were spontaneously reacted at room temperature and

atmospheric pressure The removal efficiency of H2S was 99 at the highest reaction ratio of 498

The KOH reacts with H2S more effectively than NaOH due to relatively low Gibbs free energy For

Figure 5 Removal efficiency of H2S

according to the reaction time

Figure 6 Space velocity calculation results

according to the reaction time

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

5

high removal efficiency optimal conditions of H2S removal reaction by NaOH and KOH were

reaction ratio of 498 in both cases reaction time of 006 and 0048 seconds respectively Under these

conditions the values of space velocity by NaOH and KOH were 11700 and 14900 hr-1

The input

power of plasma was required about 40 W in order to remove dusts completely In conclusion H2S

contained contaminant of 2 m3min can be efficiently removed by using the low power of 40 W in

Wet-EP system

Acknowledgments

This work was supported by the Regional Innovation Center for Environmental Technology of

Thermal Plasma (ETTP) at Inha University designated by MKE (2013)

References

[1] SS Shiffman EA Sattely Miller MS Suggs and BG Graham 1995 Brain Res Bulletin 37

369-375

[2] W H Cheng M S Chou W S Lee and B J Huang 2002 J Env Eng 128 313-320

[3] Y I Matatov-Meytal and M Sheintuch 1997 Ind Eng Chem Res 36 4374-4380

[4] Z H Huang F Kang Y P Zheng J B Yang and K M Liang 2002 Adsorp Sci amp Tech 20

495-500

[5] S W Baek J R Kim and S K Ihm 2004 CatalToday 93 575-571

[6] A H Wani R M R Branion and A K Lau 1997 J Env Sci Health A32 2027-2055

[7] J Ruan W Li Y Shi Y Nie X Wang and T Tan 2005 Chemosphere 59 327-333

[8] I Traus and H Suhr 1992 Plasma Chemistry and Plasma Processing 12 275-285

[9] Zhao Gui-Bing 2007 Chem Eng Sci 72 2216-2227

[10] E Krasheninnkov V D Rusanov S V Sanyuk and A A Fridman 1986 Zh Tekh Fiz 56

1104-1109

[11] T Nunnally K Gutsol A Rabinovich A Fridman A Starikovsky A Gutsol and RW Potter

2009 Inter J Hydro Ener 34 7618-7625

[12] S John JC Hamann SS Muknahallipatna S Legowski JF Ackerman and MD Argyle

2009 Chem Eng Sci 64 4826-4834

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

6

Since large amount of solid salts un-reacted solution and water mists were generated by

neutralization reaction of H2S with basic materials the electrostatic precipitator was used to remove

them Figure 7 indicates the removal efficiency of dust according to the plasma input power which

was varied from 1 to 180 W Dust was mostly removed above 30 W The removal efficiencies are

fairly similar each other in figures 7 (a) and (b) for NaOH and KOH respectively Amount of

exhausted dust was 0180 mgm3 at the input power of 180 W after electrostatic precipitation by

corona discharge in both cases It is very similar with the dust content in atmosphere of 0155 mgm3

Because the amount of exhausted dust without the electrostatic precipitation was over than 140 mgm3

the removal efficiencies of dust were over 99 when the input power exceeded 40 W Therefore large

amount of H2S gas and dust can be removed simultaneously at room temperature and atmospheric

pressure under continuous flow condition using the Wet-EP system

Figure 7 Removal efficiencies of dust according to the plasma input power

with (a) NaOH and (b) KOH solutions

4 Conclusion

A large amount of H2S gas diluted in air was removed in the Wet-EP system by neutralization

reaction and electrostatic precipitation under continuous flow condition NaOH and KOH were used

for neutralization reaction with H2S gas and they were spontaneously reacted at room temperature and

atmospheric pressure The removal efficiency of H2S was 99 at the highest reaction ratio of 498

The KOH reacts with H2S more effectively than NaOH due to relatively low Gibbs free energy For

Figure 5 Removal efficiency of H2S

according to the reaction time

Figure 6 Space velocity calculation results

according to the reaction time

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

5

high removal efficiency optimal conditions of H2S removal reaction by NaOH and KOH were

reaction ratio of 498 in both cases reaction time of 006 and 0048 seconds respectively Under these

conditions the values of space velocity by NaOH and KOH were 11700 and 14900 hr-1

The input

power of plasma was required about 40 W in order to remove dusts completely In conclusion H2S

contained contaminant of 2 m3min can be efficiently removed by using the low power of 40 W in

Wet-EP system

Acknowledgments

This work was supported by the Regional Innovation Center for Environmental Technology of

Thermal Plasma (ETTP) at Inha University designated by MKE (2013)

References

[1] SS Shiffman EA Sattely Miller MS Suggs and BG Graham 1995 Brain Res Bulletin 37

369-375

[2] W H Cheng M S Chou W S Lee and B J Huang 2002 J Env Eng 128 313-320

[3] Y I Matatov-Meytal and M Sheintuch 1997 Ind Eng Chem Res 36 4374-4380

[4] Z H Huang F Kang Y P Zheng J B Yang and K M Liang 2002 Adsorp Sci amp Tech 20

495-500

[5] S W Baek J R Kim and S K Ihm 2004 CatalToday 93 575-571

[6] A H Wani R M R Branion and A K Lau 1997 J Env Sci Health A32 2027-2055

[7] J Ruan W Li Y Shi Y Nie X Wang and T Tan 2005 Chemosphere 59 327-333

[8] I Traus and H Suhr 1992 Plasma Chemistry and Plasma Processing 12 275-285

[9] Zhao Gui-Bing 2007 Chem Eng Sci 72 2216-2227

[10] E Krasheninnkov V D Rusanov S V Sanyuk and A A Fridman 1986 Zh Tekh Fiz 56

1104-1109

[11] T Nunnally K Gutsol A Rabinovich A Fridman A Starikovsky A Gutsol and RW Potter

2009 Inter J Hydro Ener 34 7618-7625

[12] S John JC Hamann SS Muknahallipatna S Legowski JF Ackerman and MD Argyle

2009 Chem Eng Sci 64 4826-4834

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

6

high removal efficiency optimal conditions of H2S removal reaction by NaOH and KOH were

reaction ratio of 498 in both cases reaction time of 006 and 0048 seconds respectively Under these

conditions the values of space velocity by NaOH and KOH were 11700 and 14900 hr-1

The input

power of plasma was required about 40 W in order to remove dusts completely In conclusion H2S

contained contaminant of 2 m3min can be efficiently removed by using the low power of 40 W in

Wet-EP system

Acknowledgments

This work was supported by the Regional Innovation Center for Environmental Technology of

Thermal Plasma (ETTP) at Inha University designated by MKE (2013)

References

[1] SS Shiffman EA Sattely Miller MS Suggs and BG Graham 1995 Brain Res Bulletin 37

369-375

[2] W H Cheng M S Chou W S Lee and B J Huang 2002 J Env Eng 128 313-320

[3] Y I Matatov-Meytal and M Sheintuch 1997 Ind Eng Chem Res 36 4374-4380

[4] Z H Huang F Kang Y P Zheng J B Yang and K M Liang 2002 Adsorp Sci amp Tech 20

495-500

[5] S W Baek J R Kim and S K Ihm 2004 CatalToday 93 575-571

[6] A H Wani R M R Branion and A K Lau 1997 J Env Sci Health A32 2027-2055

[7] J Ruan W Li Y Shi Y Nie X Wang and T Tan 2005 Chemosphere 59 327-333

[8] I Traus and H Suhr 1992 Plasma Chemistry and Plasma Processing 12 275-285

[9] Zhao Gui-Bing 2007 Chem Eng Sci 72 2216-2227

[10] E Krasheninnkov V D Rusanov S V Sanyuk and A A Fridman 1986 Zh Tekh Fiz 56

1104-1109

[11] T Nunnally K Gutsol A Rabinovich A Fridman A Starikovsky A Gutsol and RW Potter

2009 Inter J Hydro Ener 34 7618-7625

[12] S John JC Hamann SS Muknahallipatna S Legowski JF Ackerman and MD Argyle

2009 Chem Eng Sci 64 4826-4834

11th APCPST and 25th SPSM IOP PublishingJournal of Physics Conference Series 441 (2013) 012004 doi1010881742-65964411012004

6