Removal Of Hydrogen Sulfide By Electrochemical

Separation and Purification Technology 62 (2008) 654–658

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Separation and Purification Technology
journal homepage: www.elsevier.com/locate/seppur

Removal of hydrogen sulfide by electrochemical method with a batchwise operation
¨ g¨ ¨ ¨ ¨ Ozgul Gercel a,∗ , A. Savas Koparal b , Ulker Bakır O˘ utveren b ¸
a b

Department of EnvironmentalEngineering, Faculty of Engineering, Anadolu University, Iki Eylul Campus, 26555 Eskisehir, Turkey ¸ Applied Research Center for Environmental Problems, Anadolu University, 26555 Eskisehir, Turkey ¸

a r t i c l e

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a b s t r a c t
This investigation demonstrated the prospects for the development of electrochemical reactor for the removal of hydrogen sulfide from sour gas at ambienttemperature. Electrochemical absorption of hydrogen sulfide in aqueous solution on Pt-expanded mesh cathode in a unique reactor design and electrode configuration was investigated with the variation in the parameters of the initial H2 S concentration, temperature, flow rate of the gas, components of gas mixture and current density. Overall, the results indicated that a good performance could be achieved forthis type of electrochemical reactor for H2 S removal. © 2008 Elsevier B.V. All rights reserved.

Article history: Received 8 November 2007 Received in revised form 12 March 2008 Accepted 19 March 2008 Keywords: Hydrogen sulfide Electrochemical absorption Electrochemical reactor

1. Introduction Energy consumption rapidly increases due to developing industrialization and increasing worldpopulation. Combustible fossil fuels, including solids, liquids and gases supply the major part of energy demand. Choosing of fuel has become a major issue and crucial factor for the protection of the environment. The major gaseous contaminant in coal gas is H2 S. The H2 S concentration depends on the type of coal and the gasification conditions but levels from 0.5 to 1.5 vol.% are typical values [1].Hydrogen sulfide removal from gas streams is important from the viewpoints of health, safety, environmental impact, corrosion of equipment during transportation and distribution and prevention of catalyst poisoning. The H2 S concentration must be reduced to 100 ppm or less, before gas stream can be used for electric generation. Additionally, hydrogen sulfide is extremely toxic to living organisms andplants. It can be detected easily at a level of 0–5 ppm in the air. When hydrogen sulfide concentration reaches 10 ppm, it can affect human health [1,2]. Much investigation has been focused in recent years on the removal of H2 S from natural or synthetic fuel gases because of environmental concerns. H2 S removal at elevated temperatures can be carried out in a number of ways. Various approaches suchas chemical absorption by alkanolamines [3], bioscrubber [2], and the oxidation of H2 S in iron-chelate process [4] have been sup-

∗ Corresponding author. Tel.: +90 222 3213550/6415; fax: +90 222 3239501. ¨ E-mail addresses: ogercel@anadolu.edu.tr (O. Gercel), askopara@anadolu.edu.tr ¸ ¨ g¨ ¨ (A.S. Koparal), uogutver@anadolu.edu.tr (U.B. O˘ utveren). 1383-5866/$ – see front matter © 2008Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2008.03.019

ported over the years. Conventional methods for the removal of H2 S involve the use of aqueous or other types of scrubbers. Sulfur is often removed using liquid absorbents based on chemical or physical absorption of hydrogen sulfide at low temperatures. Alkanolamines and their aqueous solutions will absorb hydrogen sulfide and carbondioxide at lower temperature. Methyldiethanolamine selectively removes H2 S from natural gas streams while piperazine acts mainly as a corrosion inhibitor and surfactant [3]. Another method is sorbent injection into the gasifier. In situ desulphurization can be obtained through the use of (regenerable) transition metal oxides [5]. Clinoptilolite can be effectively used for H2 S removal at...