Enhanced photocatalytic degradation of Cr(VI) and oxytetracycline using CuFeS₂@Zn composites

Water pollution caused by heavy metals and antibiotics poses a significant global challenge, necessitating the development of efficient remediation strategies. In this study, zinc (Zn) doped CuFeS₂ (copper iron sulfide) composites were used as highly efficient photocatalysts for the degradation of hexavalent chromium (Cr(VI)) and oxytetracycline (OTC) under visible light. The composites were synthesized using a facile hydrothermal method with various Zn doping concentrations (1 mol%, 5 mol%, and 10 mol%). The synthesized composites were comprehensively characterized by X-ray diffraction, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and Ultraviolet-Visible spectroscopy. X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analysis revealed their structural, morphological, optical, and surface area properties. Among the composites, 10 mol% CuFeS@Zn exhibited the highest degradation efficiency, achieving 99 % Cr(VI) and OTC removal within 100 min. This performance significantly surpasses the efficiencies of CuFeS₂, and the CuFeS₂@Zn 1 mol%, and CuFeS₂@Zn 5 mol% composites. Kinetic analysis revealed a high reaction rate constant of 3.041 min⁻¹, and optimal photocatalytic activity was observed at pH 6 and a catalyst dosage of 6 mg, with excellent recyclability and stability demonstrated over multiple cycles for the CuFeS₂@Zn 10 mol% composite. The enhanced photocatalytic performance was attributed to the improved charge carrier separation and transfer resulting from Zn incorporation, which facilitated redox reactions at the catalyst-pollutant interface. This study provides valuable insights into the design of Zn-doped CuFeS₂ composites offering a promising pathway for the development of advanced photocatalytic materials for environmental remediation.