Redox Conversion of Chromium(VI) and Arsenic(III) with the Intermediates of Chromium(V) and Arsenic(IV) via AuPd/CNTs Electrocatalysis in Acid Aqueous Solution

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• 作者：Meng Sun ; Gong Zhang ; Yinghua Qin ; Meijuan Cao ; Yang Liu ; Jinghong Li ; Jiuhui Qu ; Huijuan Liu
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：August 4, 2015
• 年：2015
• 卷：49
• 期：15
• 页码：9289-9297
• 全文大小：647K
• ISSN：1520-5851

文摘

Simultaneous reduction of Cr(VI) to Cr(III) and oxidation of As(III) to As(V) is a promising pretreatment process for the removal of chromium and arsenic from acid aqueous solution. In this work, the synergistic redox conversion of Cr(VI) and As(III) was efficiently achieved in a three-dimensional electrocatalytic reactor with synthesized AuPd/CNTs particles as electrocatalysts. The AuPd/CNTs facilitated the exposure of active Pd{111} facets and possessed an approximate two-electron-transfer pathway of oxygen reduction with the highly efficient formation of H₂O₂ as end product, resulting in the electrocatalytic reduction of 97.2 卤 2.4% of Cr(VI) and oxidation of 95.7 卤 4% of As(III). The electrocatalytic reduction of Cr(VI) was significantly accelerated prior to the electrocatalytic oxidation of As(III), and the effectiveness of Cr(VI)/As(III) conversion was favored at increased currents from 20 to 150 mA, decreased initial pH from 7 to 1 and concentrations of Cr(VI) and As(III) ranging from 50 to 1 mg/L. The crucial intermediates of Cr(V) and As(IV) and active free radicals HO^{鈥?/sup> and O₂鈥⑩€?/sup> were found for the first time, whose roles in the control of Cr(VI)/As(III) redox conversion were proposed. Finally, the potential applicability of AuPd/CNTs was revealed by their stability in electrocatalytic conversion over 10 cycles.}