Degradative removal of Sulfamethoxazole through visible light driven peroxymonosulfate activation by direct Z-scheme MIL-53(Co/Fe)/MoS2 heterojunction composite: Role of dual redox mechanism and efficient charge separation

Abstract

MIL-53(Co/Fe)/MoS2 (MIL-MS) binary photocatalyst was synthesized by a hydrothermal procedure through insitu growth of MoS2 on MIL-53(Co/Fe). In comparison to pure MIL-53(Co/Fe) and MoS2, the binary catalyst having 10 wt% MoS2 (MIL-MS(10)) (0.01 g/L) achieved 99% Sulfamethoxazole (SMX) removal (10 mg/L) through visible light driven activation of peroxymonosulfate (PMS, 0.2 g/L), at initial solution pH of 6. The formation of heterojunction enhances the charge separation efficiency, activation of adsorbed PMS moieties and harvesting of incident visible light. Surface-bound Fe2+/Fe3+|surf., Co2+/Co3+|surf. and Mo4+/Mo6+|surf.redox perform significant roles towards charge transport and production of reactive species. EPR analysis, coupled with scavenging studies indicate that radical(SO4•−,O•H,O2•−,h+)involving oxidation mechanism imparted maximum contribution towards SMX degradation. Detailed degradation pathway was designed based on substantial intermediate analysis. Excellent visible light responsiveness, charge transfer ability and reusability over multiple catalytic cycles, coupled with excellent performance in various real water matrixes established MIL-MS composite as an ideal candidate for facile removal and mineralization of refractory organic contaminants under visible light irradiation.