Molybdenum disulfide (MoS2): A novel activator of peracetic acid for the degradation of sulfonamide antibiotics.

Sulfonamide antibiotics (SAs) are typical antibiotics and have attracted increasing concerns about their wide occurrence in environment as well as potential risk for human health. In this study, we applied a novel advanced oxidation process in SAs degradation by combining molybdenum sulfide and peracetic acid (MoS2/PAA). Reactive oxygen species (ROS) including HO●, CH3C(O)O●, CH3C(O)OO●, and 1O2 were generated from PAA by MoS2 activation and contributed to SAs degradation. The effects of initial pH, the dosages of PAA and MoS2, and humic acid for SAs degradation were further evaluated by selecting sulfamethoxazole (SMX) as a target SA in the MoS2/PAA process. Results suggested that the optimum pH for SMX removal was 3, where the degradation efficiency of SMX was higher than 80% after reaction for 15 min. Increasing PAA (0.075-0.45 mM) or MoS2 (0.1-0.4 g/L) dosages facilitated the SMX degradation, while the presence of humic acids retarded the SMX removal. This MoS2/PAA process also showed good efficiencies in removing other SAs including sulfaguanidine, sulfamonomethoxine and sulfamerazine. Their possible degradation pathways were proposed based on the products identification and DFT calculation, showing that apart from the oxidation of amine groups to nitro groups in SAs, MoS2/PAA induced SO2 extrusion reaction for SAs that contained six-membered heterocyclic moieties.