Efficient removal of trace diazepam via enhanced peroxymonosulfate activation by 1T-phase and sulfur vacancy-rich MoS2-C-Fe

The pervasive use of sleeping pills has made diazepam (DZP) become a potential emerging environmental contaminant in aquatic systems. In this study, a 1 T-phase and sulfur vacancy-rich MoS 2 -C-Fe was synthesized and employed to activate peroxymonosulfate (PMS) for the efficient degradation of trace DZP. Comprehensive characterization revealed that the synergistic incorporation of iron and carbon into the MoS 2 structure optimized its electronic and surface properties, significantly enhanced PMS activation. Under appropriate conditions (100 μM PMS, 50 mg/L MoS 2 -C-Fe, and neutral pH), 97.56 % of DZP was effectively degraded, following pseudo-second-order kinetics with a rate constant of 0.0547 min −1 . Response surface methodology was employed to analyze the interactions between various parameters and their combined effects on degradation efficiency. Mechanism studies revealed that the degradation process proceeds through a combination of radical-mediated oxidation (involving SO 4 ‐ · , OH · and O 2 ‐ · ) and non-radical pathways (including 1 O 2 , high-valent iron species and surface-activated complexes). The MoS 2 -C-Fe/PMS system exhibited excellent adaptability, operational stability, and minimal metal leaching. To address challenges associated with powdered catalysts loss, an ultrasonic impregnation method was developed to immobilize the MoS 2 -C-Fe powder onto a polyurethane sponge, enhancing catalyst recyclability and extending its service life. This study offers novel insights into the removal of trace emerging contaminants and expands the potential of sulfate radical-based advanced oxidation processes for wastewater treatment.