Eco-Friendly Composite Hydrogels from Modified Gum Arabic and Agricultural Waste (Pinhão shell): A Sustainable Materials Strategy
Abstract
Abstract Hydrogels have been widely investigated as sorbent materials for wastewater treatment due to their high-water absorption capacity and adjustable physicochemical properties. In this context, the incorporation of renewable biomasses into polymeric matrices represents a sustainable strategy to enhance material performance while valorizing agro-industrial residues. This study aimed to synthesize and characterize composite hydrogels based on gum arabic modified with glycidyl methacrylate and pinhão shell bran (Araucaria angustifolia seeds), targeting potential environmental applications, such as the removal of dyes from aqueous systems. The hydrogels were prepared by chemical crosslinking, varying the concentrations of modified gum arabic and shell bran. Swelling behavior was evaluated through swelling degree measurements and kinetic studies, while the mechanism was investigated using the Power Law, Weibull, and Peppas–Sahlin models. The results showed that the composition of hydrogel composites significantly influences their swelling performance, with some formulations exhibiting superabsorbent behavior and swelling levels higher than those reported in the literature. Diffusion exponent values indicated anomalous transport for all formulations, involving the combined contribution of Fickian diffusion and macromolecular relaxation. Kinetic analysis revealed that Fickian diffusion predominated at the initial stages of swelling, while the contribution of polymer relaxation increased over time. The incorporation of pinhão shell bran did not compromise the structural integrity of the hydrogels after swelling. Overall, the composite hydrogels developed in this study demonstrated interesting properties that allow for future studies of their potential applications in the treatment of contaminated wastewater, in addition to contributing to the sustainable reuse of an abundant lignocellulosic residue.