Title : Valorization of citrus peel waste into antimicrobial zinc oxide nanocomposite films for medical packaging
Abstract:
Persistent plastic waste and the critical need for sterile materials in healthcare highlight the necessity for sustainable, high-performance alternatives. This research demonstrates the valorization of citrus peel, a significant agri-industrial waste, into functional, biodegradable nanocomposite films suitable for medical packaging. A matrix rich in pectin and cellulose was extracted from citrus peel and reinforced with zinc oxide nanoparticles (ZnO NPs) to produce films using a solvent casting method. The composites' structural, thermal, mechanical, and functional properties were systematically characterized. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed the integration of ZnO NPs within the biopolymer matrix, while scanning electron microscopy (SEM) showed homogeneous nanoparticle dispersion at lower concentrations. Incorporation of ZnO NPs enhanced the films' tensile strength and thermal stability, as indicated by mechanical testing and thermogravimetric analysis (TGA). The nanocomposites also exhibited improved barrier properties, reducing water vapor and oxygen permeability, which is essential for maintaining medical device sterility. Notably, the films demonstrated potent, dose-dependent antimicrobial activity against both *Escherichia coli* and *Staphylococcus aureus*, attributed to the release of Zn²⁺ ions and reactive oxygen species. These results indicate that citrus peel-based ZnO nanocomposites effectively combine waste valorization with advanced material functionality. The resulting films provide a renewable, biodegradable, and intrinsically antimicrobial solution, representing a promising sustainable alternative to conventional petroleum-based plastics for single-use medical packaging and supporting a circular economy with reduced environmental impact.
