Improved sulfamethoxazole degradation by the addition of MoS2 into the Fe2+/peroxymonosulfate process

The low efficiency of transforming ferric ion (Fe 3+ ) to ferrous ion (Fe 2+ ) always challenges the activation of peroxymonosulfate (PMS) by (Fe 2+ ) processes in the degradation of micro-organic contaminants. In this study, molybdenum disulfide (MoS 2 ) which accelerated PMS activation and the Fe 2+ /Fe 3+ cycle through the reaction of Mo 4+ and Fe 3+ was employed to significantly improve the efficiency of Fe 2+ /PMS on sulfamethoxazole (SMX) degradation. Through the analysis of electron paramagnetic resonance (EPR) and quenching experiments, both sulfate and hydroxyl radicals have been proven to account for SMX degradation in the MoS 2 /Fe 2+ /PMS process. The optimal pH of 3 has been determined for SMX degradation in the process, and an equation to express the relationship between the rate of SMX degradation and the dosages of Fe 2+ , MoS 2 and PMS was simulated. Chloride ion and humic acid had positive and negative effects on the process, respectively, whereas nitrate and bicarbonate had no influences on SMX degradation. Through the identified intermediates by LC/MS, a transformation pathway of SMX in the MoS 2 /Fe 2+ /PMS process was proposed. Additionally, the good efficiency of SMX degradation (>80%) in real water matrices and good stability of MoS 2 after reuse for 6 times further suggest that the MoS 2 /Fe 2+ /PMS process can be effectively used to degrade SMX.