Eco-friendly synthesis of chitosan-PVA/Ag-CeO 2 composite for crystal violet dye degradation and antibacterial performance

Environmentally friendly synthesis offers a sustainable approach to material development. In this study, Ag–CeO₂ was successfully synthesized using Morinda citrifolia L. leaf extract, which served as both a bioreductant and a stabilizer to prevent agglomeration. A chitosan–polyvinyl alcohol (PVA) matrix was used to host the synthesized Ag–CeO₂, enabling its application in crystal violet dye (CVD) degradation and antibacterial studies. The resulting Chitosan–PVA/Ag–CeO₂ composite was characterized using XRD, SEM-EDX, and UV-DRS. XRD confirmed the composite formation with diffraction patterns reflecting its constituents, whereas UV-DRS characterization identified a 2.12 eV band gap, enabling photocatalytic activity under visible light. Degradation optimization, performed via Response Surface Methodology based on Central Composite Design approach, indicated a quadratic model with optimal conditions at pH 8, 33 mg/L CVD concentration, and 145 min of irradiation, achieving 96.37% degradation efficiency. The degradation kinetics followed a pseudo-first-order model with a rate constant (k) of 0.0408 min⁻¹. FTIR analysis demonstrated composite stability with no significant spectral changes after photodegradation. TOC analysis confirmed 84.26% mineralization, and recycling tests showed only a 5.02% decrease in efficiency after five cycles. Furthermore, antibacterial assays against Staphylococcus aureus and Escherichia coli demonstrated the composite’s strong antibacterial potential.