Characterization of electrode fouling during electrochemical oxidation of phenolic pollutant
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RESEARCH ARTICLE
Characterization of electrode fouling during electrochemical oxidation of phenolic pollutant Xuefeng Liu1, Shijie You (✉)1, Fang Ma1, Hao Zhou2 1 State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China 2 Conservation Center, Shanghai Museum, Shanghai 200231, China
HIGHLIGHTS
GRAPHIC ABSTRACT
• Electrode fouling is characterized by nondestructive characterization. • Electrode fouling is highly dependent on electrochemical process. • Active chlorine can prevent the formation of polymeric fouling film.
ARTICLE INFO
ABSTRACT
Article history:
Electrode fouling is a problem that commonly occurs during electro-oxidation water purification. This study focused on identifying the fouling behavior of Pt electrode associated with the formation of polymeric layer during electro-oxidation of phenol. The in situ electrochemical measurements and non-destructive observation of the electrode morphology were reported. The results demonstrated that the electrode fouling was highly dependent on thermodynamic process of electrode that was controlled by anode potential. At anode potential lower than 1.0 V vs SHE, the direct electro-oxidation caused the electrode fouling by the formation of polymeric film. The fouling layer decreased the 2 2 electrochemically active surface area from 8.38 cm to 1.57 cm , indicated by the formation of polymeric film with thickness of 2.3 mm, increase in mass growing at a rate of 3.26 μg/cm2/min. The degree to which the anode was fouled was independent of anion in the electrolyte. In comparison, at anode potential higher than 2.7 V vs SHE, the anions (e.g., chloride) could exert a major influence to the behavior of electrode fouling. The presence of chloride was shown to mitigate the fouling of electrode significantly through preventing the formation of polymeric film by active chlorine (e.g., Cl• and Cl2) produced from anodic oxidation of chloride. Since chloride is the most abundant anionic species existing in both natural and engineered water system, this study not only offers a deep insight into the mechanism of electrode fouling, but also suggests strategies for anti-fouling in the presence of chloride in electro-oxidation process.
Received 29 April 2020 Revised 17 June 2020 Accepted 22 July 2020 Available online 9 October 2020 Keywords: Electro-oxidation Electrode fouling Polymeric film Chloride ions
© Higher Education Press 2020
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Introduction
Electrochemical oxidation represents a prominent technology in the widespread of application of decentralized water and wastewater purification (Martínez-Huitle and Ferro, 2006; Wang et al., 2020). As electrons play a role of clean reagent, electrochemical wastewater purification has become competitive by its efficient and environmentally compatible process (Tang et al., 2014; Xu et al., 2018; Qi
✉ Corresponding author E-mail: [email protected]
et al., 2020). However, electrode fouling on the anode surface impedes the practical applications of electrochemical oxidation. For example,
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