Synergistic Photocatalytic Performance and Reusability of CuO@CeO ₂ Nanocomposites for Degradation of Tetracycline Wastewater

The environmental persistence of tetracycline in aqueous systems represents a critical concern due to its recalcitrant nature and potential to exacerbate antimicrobial resistance. In response to this challenge, a novel CuO@CeO 2 nanocomposite was synthesized via a combination of hydrothermal and co-precipitation techniques. The optimized composite, with a CuO:CeO 2 molar ratio of 1:1:1, achieved a maximum degradation efficiency of 72.00% for a 200 mg/L tetracycline solution. Enhanced photocatalytic activity was attributed to the formation of a p–n heterojunction, which facilitated improved charge carrier separation and reduced the band gap energy to 2.86 eV. Kinetic analysis revealed that the Bangham (R 2 = 0.9912) and intraparticle diffusion (R 2 = 0.9810) models best described the degradation process, suggesting a coupled mechanism of surface adsorption and internal pore diffusion. Equilibrium data were most accurately represented by the Dubinin–Radushkevich isotherm (R 2 = 0.9619). Reusability assessments demonstrated that the nanocomposite retained over 85% of its initial performance across three consecutive cycles, confirming its structural integrity and operational stability. These findings highlight the potential of CuO@CeO 2 as a robust and multifunctional material for advanced antibiotic remediation, with promising applicability in integrated membrane-photocatalytic systems for industrial-scale wastewater treatment.