Chitosan films integrated with zinc oxide/reduced graphene oxide nanocomposite for malachite green degradation and antibacterial activity in sustainable packaging.

Malachite green (MG) is a synthetic triphenylmethane dye historically used in aquaculture for its antimicrobial properties, but its toxicity and residue concerns have prompted the need for alternative removal strategies. In this study, chitosan-based films incorporated with zinc oxide (ZnO) and reduced graphene oxide (rGO) nanocomposites were synthesized and assessed for their dual functionality in degrading MG and inhibiting bacterial growth. The optimized films achieved 97 % MG degradation within 120 min under visible light and exhibited strong antibacterial activity, with inhibition zones of 9.32 ± 0.27 mm against Escherichia coli and 10.23 ± 0.25 mm against Staphylococcus aureus, and a minimum inhibitory concentration (MIC) of 250 μL/mL Structural and optical characterization using XRD, FTIR, SEM, EDX, and UV-Vis DRS confirmed the successful integration and functionality of the nanocomposite. The enhanced photocatalytic efficiency was attributed to synergistic interactions between ZnO and rGO, which promoted charge separation, suppressed electron-hole recombination, and generated reactive oxygen species (ROS). Simultaneously, the chitosan matrix provided effective nanoparticle dispersion and contributed to inherent antimicrobial action. These findings demonstrate the potential of ZnO/rGO-integrated chitosan films as sustainable materials for dye wastewater remediation and antimicrobial food packaging. By effectively removing malachite green residues while providing an independent antibacterial mechanism, these films offer a safer strategy to reduce dye contamination in food-related systems.