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.

Distribution of perfluorinated compounds in Lake Taihu (China): Impact to human health and water standards

“…The analytical procedures were reported previously (Ahrens et al, 2009b;Zhou et al, 2010;Zhou et al, 2013;Zhuo et al, 2011). .…”

Fabrication of cerium-doped lead dioxide anode with improved electrocatalytic activity and its application for removal of Rhodamine B

“…For this reason, oxidation methods have been investigated for the efficient decolorization and degradation of these refractory organic dyes [4]. Electrochemical oxidation (EO) is one of the most attractive methods featuring easy implementation, high efficiency and environmental compatibility [5][6][7][8].…”

Temperature effect on photolysis decomposing of perfluorooctanoic acid

“…These methods cover various chemical process, including thermally-induced reduction (Krusic et al, 2005), microwave assisted oxidative decomposition (Lee et al, 2009(Lee et al, , 2010, sonochemical pyrolysis (Vecitis et al, 2008;Cheng et al, 2010;Moriwaki et al, 2005), electrochemical degradation (Zhuo et al, 2011;Niu et al, 2012;Lin et al, 2012b) and photochemical decomposition (Wang et al, 2008Wang and Zhang, 2011;Song et al, 2012). Among these reported methods, sonochemical, electrochemical and photochemical degradations are the most promising treatment alternatives to degrade PFOA efficiently.…”