Revamping sorghum waste into valuable films: A sustainable bioplastic with tunable properties and agro-suitability

The overuse of conventional plastics has raised critical ecological concerns, highlighting the need for sustainable alternatives. In this work, sorghum husk, an agro-waste, was valorized into cellulose–chitosan (CC) based biodegradable films. To enhance their performance, zinc oxide (ZnO) nanoparticles, synthesized from the waste filtrate of cellulose extraction, and charcoal were incorporated as fillers. The resulting biocomposites exhibited improved properties compared to neat CC films. Thermal stability increased markedly, with 20 % weight loss up to 800 °C versus 57 % in control films. Tensile strength improved from 16.4 to 19.9 MPa, while moisture content decreased significantly upon filler addition. Antioxidant activity was notably enhanced, rising from 9.6 % in CC films to 23.2 %, 31.6 %, and 72.9 % in films with ZnO nanofillers, ZnO nanocomposites, and charcoal, respectively. Seed germination tests showed that all the bioplastic films were safe for plants, promoting growth and proving to be non-toxic and highly compatible. These findings collectively underscore the potential of these cellulose-based biocomposite films as sustainable, functional, and eco-friendly alternatives for packaging and agricultural applications.