Molybdenum disulfide as excellent Co-catalyst boosting catalytic degradation of sulfamethoxazole by nZVI/PDS process

Nanoscale zero valent iron (nZVI) is environmentally friendly Fe-based materials that can effectively activate peroxydisulfate (PDS). However, the slow conversion of Fe3+ to Fe2+ limits its large-scale practical application. In this work, molybdenum disulfide (MoS2) was firstly used as a co-catalyst to facilitate the degradation performance of nZVI/PDS process for sulfamethoxazole (SMX), a typical sulfonamide antibiotic. Compared with nZVI/PDS process, the SMX degradation efficiency obtained by MoS2/nZVI/PDS system was increased by 37.2%. The addition of MoS2 could significantly accelerate the Fe2+/Fe3+ cycle, resulting in the enhanced decomposition of PDS and thus boosting catalytic degradation of SMX. Up to 98.6% degradation efficiency of SMX and 29.6% removal of total organic carbon (TOC) could be achieved under the optimal conditions within 30 min. The stability of MoS2/nZVI/PDS process for SMX removal were also certified based on five consecutive runs. Besides, electron Paramagnetic Resonance spectroscope (EPR) and radical quenching experiments identified that both sulfate radical (SO4·-) and hydroxyl radical (·OH) were responsible for SMX degradation. Based on the intermediates detected by high-resolution accurate mass quadrupole time-of-flight liquid chromatography/mass spectrometer (UPLC-QTOF-MS), possible degradation pathway of SMX was proposed. Overall, this study provides a new perspective for enhancing iron-based advanced oxidation processes with co-catalyst to achieve rapid and efficient degradation of organic pollutants in the aquatic environment.