Remediation of sulfonamides-contaminated groundwater through in-situ activation of peroxymonosulfate by supported hierarchical CuO/MgO nanosheets

Abstract

Groundwater contamination by sulfonamides (SAs) has aroused great concern due to their potential risks to ecosystem and public health. In this work, degradation of SAs with different substituents was studied via a single oxygen dominated peroxymonosulfate (PMS) activation process. Recoverable hierarchical CuO/MgO nanosheets (NSs) with highly exposure of active sites and open diffusion channels was employed as a PMS activator. The degradation behavior of sulfamethoxazole (SMX), sulfamethazine (SMZ), sulfadiazine (SDZ), sulfamerazine (SMR) and sulfathiazole (STZ) was studied via batch reactions, revealing an efficient heterogeneous oxidation process. In a fixed-bed column of the supported hierarchical CuO/MgO NSs, simultaneous degradation of the five SAs in complicated water matrix was observed with high removal efficiency, long-term stability and strong anti-interference capability toward background constituents of groundwaters. Kinetic experiments and mechanistic study elucidated PMS was activated by CuO and MgO synergically that incorporating with defective-rich MgO induced highly oxidative Cu3+. The activation of PMS over MgO was mediated by surface oxygen vacancies, while thermal feasible redox cycle of Cu3+/Cu2+ responsible for the activation of PMS over defective CuO. This study may help to understand the simultaneous degradation of different SAs in a nonradical oxidation process and provide a feasible technology for in-situ remediation of SAs-contaminated groundwater.