High-efficient elimination of roxarsone by MoS2@Schwertmannite via heterogeneous photo-Fenton oxidation and simultaneous arsenic immobilization

Roxarsone (ROX), as an antibiotic widely used in livestock industry, faces enormous challenges in its safe and effective disposal. Schwertmannite (Sch) is regarded as an appropriate environmental material for ROX decontamination, owing to its bi-functional properties of Fenton-activation and arsenic-sorption. In this study, MoS2-modified Sch (MoS2@Sch) catalyst was constructed to improve the catalytic activity for photo-Fenton reaction. The resultant MoS2@Sch showed a uniform spheroidal particles structure with average size of 750 nm, and Fe-O-Mo bond was formed in MoS2@Sch structure. Above 85% of ROX was efficiently degraded by MoS2@Sch-mediated UV-assisted heterogeneous Fenton reaction within 40 min, and the generated arsenate (As(V)) was simultaneously immobilized by catalyst. The contribution of reactive species involved in UV/MoS2@Sch-H2O2 reaction followed an order of OH ≫ O2– > h+. The improved catalytic activity of MoS2@Sch was attributable to more effective Fe3+/Fe2+ conversion, which originated from the extra electron supply from Mo4+ redox and MoS2 excitation under UV irradiation. According to theoretical computation and intermediates identification, ROX was finally transformed into CO2, NO3–, and As(V). The finding indicated that Sch-based material was alternative catalyst to realize the safe disposal of organoarsenic, whereas the stability and reusability should be further optimized for practical application.