Eco-friendly fabrication of g-C3N4/ZnO nanocomposites for visible-light-driven degradation of textile and pharmaceutical pollutants

Semiconductor photocatalysts are widely studied for wastewater purification, yet approaches that combine green synthesis with treatment of multiple pollutant classes remain limited. In this study, Tragia involucrata plant extract was employed for the eco-friendly synthesis of ZnO nanoparticles (NPs), which were then embedded into g-C₃N₄ to form g-C₃N₄/ZnO nanocomposites. Unlike most reports focusing on a single pollutant, the present work evaluates the degradation of ciprofloxacin antibiotic and a crystal violet dye, providing broader insight into real wastewater applications. Structural and optical analyses (TEM, XRD, XPS, PL) confirmed the successful incorporation of ZnO (34 nm) into g-C₃N₄, resulting in reduced recombination and enhanced charge separation. The 30 wt% ZnO composite showed superior photocatalytic performance, achieving 90% ciprofloxacin and 97% crystal violet removal within 90 min under visible light, with good recyclability across four cycles. ECOSAR analysis further demonstrated reduced toxicity of the degradation products. This study highlights a sustainable, plant-mediated route to multifunctional g-C₃N₄/ZnO photocatalysts effective against both pharmaceutical and dye pollutants.