Insights of Electrocatalytic Oxidation Mechanisms Utilizing Different Oxidants for Degradation of Organic Pollutants: Option for Sustainability

In this study, three electrochemical cocatalytic oxidation (EO) systems using different oxidants peroxysulfate (both PMS and PDS) and hydrogen peroxide (H2O2) were compared. These systems were analyzed for their degradation mechanisms and pathways of organic pollutants, specifically sulfamethoxazole (SMX), carbamazepine (CBZ), and bisphenol A (BPA). Based on quenching experiments and electron paramagnetic resonance (EPR) analyses, the EO-Fe(III)-PMS system generated multiple reactive oxygen substances (ROS) including SO4•–, •OH, and 1O2. The EO-Fe(III)-PDS process primarily utilized •OH and SO4•–, with •OH being the dominant oxidation agent. The EO-Fe(III)-H2O2 system chiefly depended on •OH, which exhibited the highest yield among the three systems. Response surface methodology (RSM) analysis suggested that the EO-Fe(III)-PMS process was less influenced by the complex water matrices. The degradation pathways for SMX, CBZ, and BPA were predicted by leveraging mass spectrometry (MS) data. Biotoxicity assessments revealed that the EO-Fe(III)-H2O2 system is the most apt for SMX elimination. Meanwhile, the EO-Fe(III)-PMS system displayed environmentally friendly characteristics during CBZ oxidation compared to the other two systems. Overall results indicate the pros and cons of electrochemical catalytic systems utilizing different oxidants, offering insights into future options of treatment strategies based on their individual merits and sustainability.