title: Efficient electrochemical oxidation of perfluorooctanoate using a Ti/SnO2-Sb-Bi anode.
abstract: The electrochemical decomposition of persistent perfluorooctanoate (PFOA) with a Ti/SnO2-Sb-Bi electrode was demonstrated in this study. After 2 h electrolysis, over 99% of PFOA (25 mL of 50 mg·L(-1)) was degraded with a first-order kinetic constant of 1.93 h(-1). The intermediate products including short-chain perfluorocarboxyl anions (CF3COO-, C2F5COO-, C3F7COO-, C4F9COO-, C5F11COO-, and C6F13COO-) and F- were detected in the aqueous solution. The electrochemical oxidation mechanism was revealed, that PFOA decomposition first occurred through a direct one electron transfer from the carboxyl group in PFOA to the anode at the potential of 3.37 V (vs saturated calomel electrode, SCE). After that, the PFOA radical was decarboxylated to form perfluoroheptyl radical which allowed a defluorination reaction between perfluoroheptyl radical and hydroxyl radical/O2. Electrospray ionization (ESI) mass spectrum further confirmed that the oxidation of PFOA on the Ti/SnO2-Sb-Bi electrode proceeded from the carboxyl group in PFOA rather than C-C cleavage, and the decomposition processes followed the CF2 unzipping cycle. The electrochemical technique with the Ti/SnO2-Sb-Bi electrode provided a potential method for PFOA degradation in the aqueous solution.
authors.affiliation: POPs Research Centre, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Qiongfang
authors.initials: Q
authors.lastname: Zhuo
authors.forename: Shubo
authors.initials: S
authors.lastname: Deng
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
mesh_terms: D000965:Antimony / Q000737:chemistry*; D001729:Bismuth / Q000737:chemistry*; D002210:Caprylates / Q000737:chemistry*; D004566:Electrodes; D004572:Electrolysis / Q000379:methods; D004785:Environmental Pollutants / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods; D005466:Fluorocarbons / Q000737:chemistry*; D010084:Oxidation-Reduction; D017971:Tin Compounds / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D002210:Caprylates; D004785:Environmental Pollutants; D005466:Fluorocarbons; D017971:Tin Compounds; C009495:titanium dioxide; C023036:perfluorooctanoic acid; D000965:Antimony; D014025:Titanium; C045358:stannic oxide; D001729:Bismuth