Dual Electrodes Oxidation of Dye Wastewater with Gas Diffusion Cathode
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- 作者：Zhemin Shen ; Ji Yang ; Xiaofang Hu ; Yangming Lei ; Xiuling Ji ; Jinpin Jia ; and Wenhua Wang
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：March 15, 2005
- 年：2005
- 卷：39
- 期：6
- 页码：1819 - 1826
- 全文大小：304K
- 年卷期：v.39,no.6(March 15, 2005)
- ISSN：1520-5851
文摘
The high energy cost of an electrochemical method is thefatal drawback that hinders its large scale applicationin wastewater treatment. In traditional single-chamberelectrolysis cell, only direct oxidation at an anode exists.Although a small amount of hydrogen peroxide is producedat the cathode by reduction, it is transferred to theanode and destroyed there without adding much benefitto organic decomposition. A two-chamber electrolytic cell,connected with an electrolyte bridge, was developed inthis work. In this new reactor, direct oxidation at anode andindirect oxidation by hydrogen peroxide at cathode canoccur simultaneously. Therefore "dual electrodes oxidation"in one electrochemical reactor was achieved successfully.Compared to a traditional one cell reactor, this reactorcuts the energy cost by 50%, and thus might lead toreconsideration of the electrochemical role in wastewatertreatment. A Pt/C gas diffusion electrode (GDE) isfabricated and used as a cathode fed with oxygen-containing gases to produce hydrogen peroxide. Whenpurified air diffuses through the active layer on the GDE,oxygen is reduced to hydrogen peroxide with a high yield todecompose organics. It has been found that the directoxidation process at an anodic zone is slightly affected byfactors such as pH variation, Fe(II) existence and aeration,while indirect oxidation at the cathodic zone is stronglyaffected. Dye used as a model pollutant was oxidized intosmall organic acids in both anode and cathode regionsin this electrolytic reactor. GC-MS and IR spectrum wereemployed to analyze the intermediates formed duringthe degradation. Twenty intermediates have been detected,including 14 esters, 3 acids and 3 compounds with NO2or N-OH groups. Thereafter, the degradation pathways ofdye Acid Red B are proposed.