Rapid degradation of sulfamethoxazole by permanganate combined with bisulfite: efficiency, influence factors and mechanism.

ABSTRACT

In this study, permanganate combined with bisulfite (PM/BS), a novel advanced oxidation process, was used for rapidly removing sulfamethoxazole (SMX) from contaminated water. The results showed that 80% SMX was removed within 10 s in the PM/BS system, while no obvious SMX degradation was observed in the PM or BS alone system within 300 s. Reactive manganese species (RMnS, Mn(III), Mn(V) and Mn(VI)), sulfate radical (SO4•-) and hydroxyl radical (HO•) formed in the PM/BS system all played a role in accelerated degradation of SMX. Due to the loss of RMnS, SMX degradation was significantly inhibited with the increase in pH. The best [BS][PM] ratio for SMX removal was 7.51-101. The presence of Cl-, HCO3- or natural organic matter (NOM) significantly inhibited the degradation of SMX, while SO42- and NO3- had little impact on SMX removal. Based on the detected transformation products, two degradation pathways of SMX by PM/BS, namely N-S bond cleavage and amino oxidation, were proposed.