Synergistic effect of in-situ generated hydrogen peroxide on the degradation of sulfamethoxazole (SMX) by 1T-2H phase MoS2-activated PAA

Abstract

Activation of peracetic acid (PAA) for pollutants degradation has been a hotspot recently. In this paper, sulfamethoxazole (SMX) is selected as the target pollutant, the degradation system consists of a TiO2 photoanode loaded with 1T-2H phase MoS2 and a nitrogen-doped ZnO cathode. The octahedral coordination and metallic properties of 1T-phase molybdenum disulfide endowed 1T-2H MoS2 with enhanced catalytic performance. Meanwhile, the cathode exhibited outstanding capabilities in generating H2O2 and facilitating its decomposition. In a weakly acidic environment, the SMX removal ratio of the 1T-2H MoS2/N-ZnO/PAA system within 30 min is 96.8 %, which is significantly higher than that of the 1T-2H MoS2/Pt/PAA system at 44.9 % and the 1T-2H MoS2/N-ZnO system at 33.1 %. After OH quenching, the degradation rate of PAA was found to significantly decrease, while the degradation rate of SMX remained almost unchanged. This suggests the hydroxyl radical (OH) preferentially reacts with PAA, leading to the formation of CH3C(O)OO rather than attacking SMX. This co-activation accelerates the formation of CH3C(O)OO and further promotes the degradation of SMX. Overall, this study systematically investigated the overlooked but crucial role of H2O2 in the decomposition of PAA process, which might provide valuable insights for better understanding the underlying mechanism in catalyzed PAA processes.