Novel magnetically retrievable SnO2/Fe3O4/WSe2 heterojunction for the photocatalytic degradation of tinidazole through a synergistic strategy for environmental remediation

Wastewater effluents are known to contain a diverse range of organic contaminants, among which pharmaceutical residues constitute a significant and persistent fraction. The escalating global challenge of antimicrobial resistance highlights the urgent need for innovative and sustainable remediation strategies. In this context, the present study reports the rational design and fabrication of a ternary SnO2/Fe3O4/WSe2 (SFW) heterostructure via a hydrothermal synthesis route. The incorporation of Fe3O4 endows the composite with magnetic properties, facilitating facile recovery and recyclability via an external magnetic field, whereas SnO2 contributes strong oxidative potential and high electron mobility. Meanwhile, WSe2, a narrow-bandgap semiconductor, enhances visible-light harvesting and promotes efficient charge transfer, thereby enhancing the overall photocatalytic activity of the SFW nanocomposite. The photocatalytic performance of the synthesized SFW catalyst was systematically evaluated through the degradation of tinidazole (TNZ) under visible-light irradiation, achieving an impressive degradation efficiency of 89.28% within 60 min under optimized conditions. The influence of critical operational parameters, such as catalyst dosage, H2O2 concentration, and initial pollutant load, was systematically investigated to establish the optimal degradation conditions. Additionally, the degradation pathway was proposed based on the VB-XPS analysis and reactive oxygen species (ROS) identification via scavenging assays. The effect of coexisting ions, other pharmaceuticals, and different water matrices was also examined to assess the environmental applicability of the catalyst. Notably, the inclusion of Fe3O4 markedly enhanced the magnetic recoverability of the photocatalyst over the subsequent catalytic runs, significantly enhancing the practicality of the SFW system for real-world wastewater treatment applications.