A simple Fe3+/bisulfite system for rapid degradation of sulfamethoxazole

摘要

Sulfate radical (SO _(4) ˙ ~(?) ) based oxidation technologies have been widely used in the remediation of antibiotic-containing wastewater. Activated persulfates are efficient reagents for achieving SO _(4) ˙ ~(?) , but the storage and transportation of concentrated persulfates present associated safety issues. In this study, bisulfite (BS) was used as an alternative precursor for replacing persulfates, and a simple advanced oxidation system (Fe ~(3+) /BS) for generating SO _(4) ˙ ~(?) and hydroxyl radical (HO˙) was formulated and evaluated for removing sulfamethoxazole (SMX) from contaminated water. The initial pH, dosages of Fe ~(3+) and BS, as well as the water matrix were investigated to improve the SMX degradation. The results indicated that 1 μmol L ~(?1) SMX was completely removed within 5 min at optimum initial pH of 4.0, Fe ~(3+) dosage of 10 μmol L ~(?1) , BS dosage of 100 μmol L ~(?1) and temperature of 25 °C. The presence of HCO _(3) ~(?) and natural organic matter (NOM) showed obviously negative effects on SMX degradation, while Cu ~(2+) could slightly promote the degradation of SMX if its concentration was in an appropriate range (～1 μmol L ~(?1) ). Scavenger quenching experiments confirmed the presence of SO _(4) ˙ ~(?) and HO˙, which resulted in efficient SMX degradation in the Fe ~(3+) /BS system. During the radical chain reactions, Fe ~(2+) and Fe ~(3+) could be converted into each other to form self-circulation in this system. The degradation pathway of SMX by Fe ~(3+) /BS was proposed including hydroxylation and bond cleavage.