Photocatalytic reduction of selenite and selenate using TiO₂ photocatalyst

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• 作者：Nguyen ; Vi Nu Hoai ; Beydoun ; Donia ; Amal ; Rose
• 关键词：Selenite ; Selenate ; Photoreduction ; Titanium dioxide ; Mechanism
• 刊名：Journal of Photochemistry & Photobiology ; A ; Chemistry
• 出版年：2005
• 期刊代码：66_10106030
• 类别：ch
• 出版时间：April 30, 2005
• 卷：171
• 期：2
• 页码：113-120
• 文件大小：381 K

摘要

The fate of selenite (Se(IV)) and selenate (Se(VI)) ions in illuminated TiO₂ suspensions was studied. In the presence of formic acid as a hole scavenger, both Se(IV) and Se(VI) were photoreduced to Se(0). The Se(0) deposited as either separate particles or a film on the TiO₂ particles. UV–vis reflectance measurements showed that the Se–TiO₂ powders were red-shifted relative to pure TiO₂ with an additional absorbance band at around 680 nm, attributed to Se(0). The photocatalytic reduction mechanism of selenium ions, with focus on selenite photoreduction, is discussed. It is proposed that direct reduction of Se(IV) by the electrons photogenerated in TiO₂ resulted in the formation of a Se(0) film while the formation of Se(0) particles was due to a chemical reaction between Se(IV) and Se(2−). The Se(2−) is believed to have been generated from the six electron photoreduction of Se(IV) and/or further photoreduction of Se(0) deposits.