Photocatalytic Oxidation of Arsenite over TiO(2): Is Superoxide the Main Oxidant in Normal Air-Saturated Aqueous Solutions?

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	Photocatalytic Oxidation of Arsenite over TiO(2): Is Superoxide the Main Oxidant in Normal Air-Saturated Aqueous Solutions?
	H. Fei; W. H. Leng; X. Li; X. F. Cheng; Y. M. Xu; J. Q. Zhang; C. N. Caom
	2011
发表期刊	Environmental Science & Technology
ISSN	0013-936X
卷号	45 期号:10 页码:4532-4539
摘要	TiO(2) photocatalytic oxidation (PCO) of As(III) in the normal air-saturated aqueous solutions has been widely studied. Yet no consensus has been achieved on the mechanism whether superoxide is the main oxidant, although many approaches have been taken. (Photo)electrochemical method can minimize changes to TiO(2) surface and could therefore not alter the normal mechanism. In this Article, both this approach and As(III) oxidation kinetic measurements were performed to clarify the disputed mechanism. Under a sufficient cathodic bias potential, the dark oxidation of As(III) by superoxide could occur, but both the reaction rate and the columbic efficiency were rather low, suggesting that it is a weak oxidant. However, under UV light, both the reaction rate and the columbic efficiency were greatly enhanced even at potentials negative enough to eliminate photohole participation, indicating that more efficient oxidants than superoxide were produced. Under UV illumination and enough positive potential where superoxide was absent, the As(III) oxidation was the most highly efficient. The columbic efficiency of photoholes was much higher than that of superoxide. In the normal aerated aqueous solutions and at open circuit, although the total contribution of superoxide and its derivates to the PCO of As(III) was considerably high (up to 43%), it was not more than that of photohole (57%). In addition, the reported various approaches taken to elucidate the mechanism were discussed, and the resulting disputes can be clarified by these findings. It was demonstrated that (photo)electrochemical method could provide direct and undisputed evidence to reveal the truth mechanics issues.
部门归属	[fei, hui; leng, wenhua; li, xiang; cheng, xiaofang; xu, yiming; zhang, jianqing; caom, chunan] zhejiang univ, dept chem, hangzhou 310027, zhejiang, peoples r china. [caom, chunan] chinese acad sci, inst met res, state key lab corros & protect met, shenyang 110016, peoples r china.;leng, wh (reprint author), zhejiang univ, dept chem, yuquan campus, hangzhou 310027, zhejiang, peoples r china;lengwh@zju.edu.cn
关键词	Nanocrystalline Titanium-dioxide Mechanism Involving Superoxides Alternative Electron-acceptors Hydrogen-peroxide Film Electrodes As(Iii) Adsorption Photooxidation Recombination Arsenic(Iii)
URL	查看原文
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/30318
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	H. Fei,W. H. Leng,X. Li,et al. Photocatalytic Oxidation of Arsenite over TiO(2): Is Superoxide the Main Oxidant in Normal Air-Saturated Aqueous Solutions?[J]. Environmental Science & Technology,2011,45(10):4532-4539.
APA	H. Fei.,W. H. Leng.,X. Li.,X. F. Cheng.,Y. M. Xu.,...&C. N. Caom.(2011).Photocatalytic Oxidation of Arsenite over TiO(2): Is Superoxide the Main Oxidant in Normal Air-Saturated Aqueous Solutions?.Environmental Science & Technology,45(10),4532-4539.
MLA	H. Fei,et al."Photocatalytic Oxidation of Arsenite over TiO(2): Is Superoxide the Main Oxidant in Normal Air-Saturated Aqueous Solutions?".Environmental Science & Technology 45.10(2011):4532-4539.