Electrochemical methods for treatment of per- and polyfluoroalkyl substances (PFAS): A review

Abstract

Per- and polyfluoroalkyl substances (PFAS) are compounds with thermodynamically robust carbon-fluorine (C-F) bonds that are found in various consumer products and industrial facilities. The persistence of these compounds poses a significant threat to the environment, resulting in water and soil contamination and a negative impact on human health. Therefore, various methods, such as adsorption, biological degradation, filtration and electrochemical have been developed to investigate the detection and complete remediation of PFAS from the environment. Among all the techniques used, electrochemical methods have been shown to be promising. In this review, the occurrences of PFAS in the environment and the implementation of electrochemical techniques (electrocoagulation (EC), electrochemical oxidation (EO) and electrosorption) for the treatment of PFAS are discussed. Along with those, a proposed degradation mechanism of PFAS by EO involving the cleavage of the C-F bonds of PFAS by Kolbe decarboxylation or desulfonation and oxidation to form short-chain PFAS molecules is also highlighted. In addition, the challenges encountered using these approaches and the adoption of different treatment systems, such as ultraviolet (UV), foam fractionation (FF) and adsorption with electrochemical methods to enhance the PFAS removal efficiency are presented. Nonetheless, the implementation of feasible approaches, evaluation of environmentally relevant concentrations of PFAS as well as assessment of the stability and durability of electrode materials are essential for the implementation of electrochemical techniques in full-scale applications.