Agro-waste-mediated green synthesis of Cu₂O/ZnO nanocomposites for photocatalytic removal of doxycycline in aqueous system

A green and sustainable route was developed for the synthesis of Cu₂O/ZnO nanocomposites (NCs) using beetroot peel extract (BPE) as a dual reducing and stabilizing agent. The biogenic method utilizes phytochemicals from agro-waste to fabricate a catalyst that efficiently degrades the antibiotic doxycycline (DC) under visible light. Comprehensive characterization through different physicochemical techniques confirmed the successful formation of crystalline Cu₂O/ZnO NCs with well-defined morphology. The photocatalyst achieved ~90.5% degradation of DC within 180 min, following pseudo-first-order kinetics with a rate constant of 0.0098 min⁻¹. The catalyst demonstrated excellent stability and recyclability over five consecutive cycles, with no significant loss in activity. This eco-friendly and cost-effective approach not only valorizes agricultural waste but also advances sustainable photocatalytic technology for pharmaceutical wastewater treatment, contributing to multiple Sustainable Development Goals.