Enhanced perfluorooctane acid mineralization by electrochemical oxidation using Ti3+ self-doping TiO2 nanotube arrays anode. (January 2022)

• Record Type: Journal Article
• Authors: Wang, Chong; Zhang, Tianai; Yin, Lifeng; Ni, Chengsheng; Ni, JiuPai; Hou, Li-An
• Is Part Of: Chemosphere. Volume 286:Part 2(2022)
• Publication Date: 2022-01
• Subjects: Perfluorooctanoic acid (PFOA) -- TiO2 nanotube -- Electrochemical oxidation -- Cathodic polarization -- Mechanisms; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.131804
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Perfluorooctanoic acid (PFOA) is of increasing concern due to its worldwide application and extremely environmental persistence. Herein, we demonstrated the electrochemical degradation of PFOA with high efficiency using the Ti 3+ self-doping TiO2 nanotube arrays (Ti 3+ /TiO2 -NTA) anode. The fabricated Ti 3+ /TiO2 -NTA anode exhibited vertically aligned uniform nanotubes structure, and was demonstrated good performance on the electrochemical degradation of PFOA in water. The degradation rate, total organic carbon (TOC) removal rate and defluorination rate of PFOA reached 98.1 %, 93.3 % and 74.8 %, respectively, after electrolysis for 90 min at low current density of 2 mA cm −2 . The energy consumption (7.6 Wh L −1 ) of this electrochemical oxidation system using Ti 3+ /TiO2 -NTA anode for PFOA degradation was about 1 order of magnitude lower than using traditional PbO2 anodes. Cathodic polarization could effectively prolong the electrocatalytic activity of the anode by regenerating Ti 3+ sites. PFOA molecular was underwent a rapidly mineralization to CO2 and F −, with only low concentration of short-chain perflfluorocarboxylic acids (PFCAs) intermediates identified. A possible electrochemical degradation mechanism of PFOA was proposed, in which the initial direct electron transfer (DET) on the anode to yield PFOA free radicals (C7 F15 COO) and hydroxyl radicals (OH) oxidation were greatly enhanced. This presented study provides a novel approach for the purification of the recalcitrant PFOA from wastewaters. Graphical abstract: Image 1 Highlights: Ti 3+ self-doping TiO2 nanotube arrays anode was fabricated with high electrochemical activity. Electrochemical degradation of PFOA followed pseudo-first-order kinetics. High mineralization and low energy consumption were achieved. The electrochemical mineralization mechanism of PFOA was elucidated.