Study on the importance of the reductive degradation of GenX in its overall electrochemical degradation process on different cathode materials

Per- and polyfluoro alkylated substances (PFAS) are well known for their recalcitrant nature caused by the abundance of CF bonds. It has been proven that electrochemical degradation is a potentially suitable technique for treating PFAS; however, most studies solely focus on electrochemical oxidation, with limited attention given to electrochemical reduction, and the relative contribution of the two towards the total PFAS degradation has not yet been elucidated. This manuscript reports an investigation on the contribution of electroreduction to the overall electrodegradation of a target PFAS, HFPO-DA (i.e. GenX), using a boron doped diamond (BDD) anode and different cathode materials (Cu, Ti, Au). The oxidation and reduction reactions were successfully decoupled from each other and studied simultaneously using an electrochemical H-cell with an agar membrane. It was determined that reduction plays a significant role in the overall degradation of GenX for each of the cathodes studied, with its contribution ranging from 52 % for the Ti cathode, to 66 % for Cu, and to 92 % for Au.