Electrochemical activation of peracetic acid with activated carbon fiber cathode for sulfamethoxazole elimination: Long-lasting catalytic performance and mechanism

Advanced oxidation processes (AOPs) based on peracetic acid (PAA) could generate various radicals with low byproduct generation, making them a vital technology in the remediation of organic pollution. Maintaining the activity and continuous operation of catalytic systems in water treatment processes was a highly challenging research topic. Herein, the electrochemical process with an activated carbon fiber (E-ACF) cathode was devised to boost the activation of PAA (E-ACF-PAA) for persistent elimination of organics. Compared to other commonly used electrodes, the ACF cathode displayed superior PAA activation ability and higher sulfamethoxazole (SMX) removal. The applied cathodic electric field could protect ACF from PAA oxidation, maintaining its long-term catalytic ability over 50 cycles. Based on radical quenching studies, the EPR test, and the estimation of radical contribution, the E-ACF-PAA process was identified as a radical dominant system. Importantly, isolated chamber experiments proved that PAA was mainly decomposed on the cathode to produce hydroxyl radicals (center dot OH) for SMX degradation, while the anode played a negligible role. According to toxicity prediction and algae growth tests, the degradation products were harmless to the aquatic ecology. Remarkably, continuous flow experiments over a 24 h and different water matrix tests have also proven applicability in practical scenarios. This work provided novel insights into the electrochemical activation of PAA and further expanded the potential applications of PAA-based AOPs in the remediation of organic pollution.