Kinetics and mechanism of synergistic adsorption and persulfate activation by N-doped porous carbon for antibiotics removals in single and binary solutions

Abstract

Porous carbon serves as a green material for efficient wastewater purification by adsorption and advanced oxidation processes. However, a clear understanding of the simultaneous removal of multiple pollutants in water is still ambiguous. Herein, the synergistic effect of adsorption and peroxydisulfate (PS) activation on kinetics and mechanism of removing single and binary antibiotic pollutants, sulfamethoxazole (SMX) and ibuprofen (IBP), from water by biomass-derived N-doped porous carbon was investigated. Our findings suggest that adsorption contributed to efficient removals of SMX/IBP. Comparative quenching experiments and electrochemical analysis demonstrated that hydroxyl (•OH) and sulfate (SO4•−) radicals, as well as singlet oxygen (1O2) led to the catalytic degradation of SMX, while only 1O2 reacted for IBP oxidation. Superoxide ion (O2•−) radicals were not related to SMX/IBP degradation. Electron transfer pathway accounted for PS activation but was not involved in direct SMX/IBP oxidation. Only slight differences were found between the degradation kinetics of SMX and IBP in the binary and single SMX or IBP solutions. This arose from the non-selective effect of adsorption and 1O2 attack for SMX/IBP removal, and the weak selective oxidation process of SMX by •OH and SO4•−. This study provides a new viewpoint on the role of adsorption in catalysis and enriches the mechanistic study of multi-component antibiotic degradation.