Plant-mediated synthesis of Mo-doped ZnO/Ag₃VO₄ nanocomposites using Vernonia amygdalina for efficient photodegradation of tinidazole drug

Effluents containing pharmaceutical and organic pollutants from different sources are a major concern in the global environmental issue. Pharmaceutical wastes in Ethiopia are a significant problem, primarily caused by expiration due to poor inventory management, like overstocking. In this study, a plant-mediated Mo-doped ZnO/Ag₃VO₄ ternary nanocomposite was synthesized using Vernonia amygdalina extract via a precipitation method for the photodegradation of Tinidazole drug (TIN). The crystalline phase, surface morphology, functional groups, charge carrier dynamics, and optical characteristics of the as-synthesized materials were investigated by XRD, SEM-EDX, FTIR, PL, and UV–Vis DRS, respectively. The performance of the photodegradation of TIN drug under visible light followed the order: plant-mediated Mo-doped ZnO/Ag₃VO₄ > bare Mo-doped ZnO/Ag₃VO₄ > ZnO/Ag₃VO₄ > Mo-doped ZnO > Ag₃VO₄ > ZnO. Under optimized conditions, the plant-mediated Mo-doped ZnO/Ag₃VO₄ photocatalyst exhibited 95% degradation in 180 min under visible light and 98% in an outdoor experiment in sunlight irradiation. To investigate the real-world application of the as-synthesized photocatalyst, laboratory-simulated mixed pharmaceutical drugs were prepared, and the degradation efficiencies of 80.6% (indoor) and 84.8% (outdoor) were obtained. Reusability tests demonstrated stable performances of 60.9% in the 5th cycle. Scavenger experiments revealed that photodegradation was primarily driven by superoxide radicals, followed by ̇ OH-radicals and photogenerated h + . These results demonstrate the potential of plant-mediated Mo-doped ZnO/Ag₃VO₄ nanocomposites as efficient and reusable photocatalysts for pharmaceutical wastewater treatment under visible light.