title: 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.
abstract: 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 ± 2.4% of Cr(VI) and oxidation of 95.7 ± 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(•) and O2(•-) 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.
authors.affiliation: †Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.|§University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Sun
authors.affiliation: †Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.|§University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Gong
authors.initials: G
authors.lastname: Zhang
authors.affiliation: †Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.|§University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Qin
authors.affiliation: ∥Beijing Engineering Research Center of Printed Electronics, School of Printing and Packaging Engineering, Beijing Institute of Graphic Communication, Beijing 102600, China.
authors.forename: Meijuan
authors.initials: M
authors.lastname: Cao
authors.affiliation: ‡Department of Chemistry, Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Tsinghua University, Beijing 100084, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: ‡Department of Chemistry, Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Tsinghua University, Beijing 100084, China.
authors.forename: Jinghong
authors.initials: J
authors.lastname: Li
authors.affiliation: †Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Jiuhui
authors.initials: J
authors.lastname: Qu
authors.affiliation: †Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liu
mesh_terms: D000143:Acids / Q000737:chemistry*; D001151:Arsenic / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D004560:Electricity; D004563:Electrochemistry / Q000379:methods*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006861:Hydrogen Peroxide; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011789:Quantum Theory; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D000143:Acids; D005609:Free Radicals; D037742:Nanotubes, Carbon; D012996:Solutions; D014867:Water; D002857:Chromium; C074702:chromium hexavalent ion; D010165:Palladium; D006046:Gold; D006861:Hydrogen Peroxide; D001151:Arsenic