Valorization of Food Industry Waste: Chitosan-Based Hybrid Aerogels as Regenerable Platforms for Textile Wastewater Treatment

Global challenges regarding resource depletion and waste accumulation necessitate the transition toward a circular economy through innovative recycling technologies. A key strategy in this shift is the valorization of industrial by-products into high-added-value materials. This study aligns with these goals by utilizing chitosan, a biopolymer derived from crustacean shell waste from the food processing industry, as a sustainable and economic alternative to synthetic polymers for water treatment technologies. These renewable and biodegradable materials are intrinsically functionalized with hydroxyl (-OH) and amine (-NH₂) groups, serving as crucial coordination sites for pollutants. In this work, glutaraldehyde-crosslinked chitosan hydrogels and aerogels were engineered as beads, incorporating the poly(ionic liquid) as a soft template to enhance performance. The integration of PIL significantly increased hydrophilicity, with equilibrium swelling ratios rising from 111.6% to 143.1%, thereby improving active site accessibility. Adsorption assessments for synthetic dyes, Direct Red 80 (DR80), Acid Orange II (OII), and Reactive Blue 5 (RB5) demonstrated that the PIL-Cl strategy boosted maximum capacities (q_max), notably increasing RB5 uptake from 550 to 883 mg g^-1. Crucial to the circularity metrics of this technology, the material showed high recyclability. Regeneration via NaOH washing achieved desorption efficiencies up to 85.8% for OII, maintaining robust performance across multiple cycles. By transforming an abundant bio-waste into a high-capacity, regenerable platform for textile effluent remediation, this research demonstrates a successful model for industrial symbiosis. It highlights how bio-based recycling and material innovation can displace primary resources, offering a technically viable and environmentally conscious solution for the protection of water resources.