Enhanced photocatalytic degradation of tetracycline using cobalt-substituted ZnFe2O4 porous microspheres under visible-LED irradiation

We developed an advanced method for separation of organic materials from water in adsorption process. Advanced functional inorganic materials were designed and synthesized using hydrothermal method. Photocatalytic processes are among the most effective and sustainable methods for eliminating synthetic toxic organic pollutants and pharmaceuticals. The removal of toxic contaminants from water necessitates the implementation of advanced oxidation processes (AOPs) that utilize highly efficient photocatalysts. Furthermore, the design of visible-light-responsive photocatalysts for AOPs requires a balance of cost-effectiveness and efficiency. This study focuses on developing a sustainable synthetic route to obtain a photocatalyst with enhanced activity while minimizing environmental impact. Specifically, pure (ZFC0) and 10wt% cobalt- substituted ZnFe₂O₄ (ZFC10) microspheres were synthesized using a hydrothermal method, and their morphology and crystallinity were studied. These microspheres were employed as catalysts for the degradation of three commercial pharmaceuticals: tetracycline, paracetamol, and antihistamines. Notably, the combination of ZF and cobalt facilitates a surface contact that effectively inhibits the recombination of electron-hole pairs, thereby enhancing charge transfer between the two materials and resulting in improved photocatalytic oxidation. The photocatalytic activity was assessed for varying concentrations of tetracycline and ZFC10. Under irradiation from a mercury vapor lamp, ZFC10 achieved a tetracycline degradation efficiency of up to 83% within 180 min (60 min in darkness and 120 min under light), nearly double the degradation observed under LED light. Additionally, ZFC10 exhibited excellent reusability and chemical stability after three cycles. The study also discusses the underlying photocatalytic mechanisms.