Eco-friendly fabrication of biopolymer films from tannery waste, zinc oxide nanoparticles, and crustacean shells: Advancing sustainable circular bio-economy

The leather industry is a major source of environmental pollution, particularly through the generation of solid wastes such as trimming residues. Valorization of this waste into high-value biopolymers offers a sustainable strategy to reduce environmental impact while replacing non-biodegradable plastics. In this study, gelatin extracted from trimming waste was combined with polyvinyl alcohol (PVA) to fabricate a biodegradable film, serving as the control system. To enhance functional properties, two modified films were prepared by separately incorporating chitosan (sourced from shrimp shell waste) and zinc oxide nanoparticles (ZnO-NPs The prepared films were extensively characterized using FTIR, XRD, SEM, TGA, and DLS, alongside mechanical testing (tensile strength, elongation at break), water vapor permeability, solubility, and adsorption analyses. In addition, antimicrobial activity, cytotoxicity, soil burial degradation, and visual appearance were evaluated to assess practical applicability. Comparative analysis revealed that both chitosan and ZnO-NPs incorporation improved the performance of gelatin–PVA films relative to the control. ZnO-NPs films exhibited superior biodegradability and antimicrobial properties, while chitosan films demonstrated enhanced moisture resistance, making them more suitable for food packaging. This study highlights an effective strategy for valorizing industrial and marine waste into multifunctional biopolymer films, offering a sustainable alternative to conventional plastics in packaging applications.