Biodegradable films from the lignocellulosic fibers of wheat straw biomass and the effect of calcium ions

Abstract

Plastics are hazardous to human health, and plastic waste results in environmental pollution and ecological catastrophe. Biobased polymers from renewable sources have recently become promising for developing biodegradable packaging films. Among them, lignocellulosic residue from agricultural biomass is inexpensive, renewable, and biodegradable. This study aims to develop biodegradable films using lignocellulosic residue from wheat straw biomass. The methodology is a green process that solubilizes lignocellulosic chains using Zn²⁺ ions and crosslinks with Ca²⁺ ions of different concentrations (200-800 mM). The results reveal that the increase of Ca²⁺ ions significantly decreases moisture content, water solubility, water vapor permeability, transparency, and elongation of films. The tensile strength is recorded as 6.61 ± 0.07 MPa with the addition of 800 mM of CaCl₂, which is approximately 2.5 times higher than commercial polyethylene films. Around 90 % of films biodegrade within a month in soil containing 20 % moisture content. Overall, lignocellulosic residue from wheat straw biomass could be an excellent replacement for synthetic polymer to fabricate strong, transparent, and biodegradable plastic films.

Keywords: CaCl(2) crosslink; Cellulose; Film; Wheat straw; ZnCl(2) solution.