Tailor-made amine functionalized lignin/cellulose beads for remediation of hexavalent chromium

Amid growing global environmental challenges, biomass-derived materials have emerged as sustainable and eco-friendly solutions for industrial pollution. This study developed polyethylenimine (PEI)-functionalized lignin/cellulose beads (PLCBs) as high-performance biosorbents for removing hexavalent chromium (Cr (VI)) from aqueous solutions. The beads were prepared through a two-step process: first, water-soluble carboxymethyl cellulose and lignosulfonate were transformed into stable beads via ion crosslinking; second, the beads were functionalized with PEI to introduce abundant cationic amine groups. Comprehensive characterization confirmed the excellent underwater stability, mechanical robustness, and pH-responsive surface charge of the material. Batch and continuous column experiments demonstrated the exceptional Cr(VI) adsorption performance of the functionalized beads, with a maximum capacity of approximately 326.80 mg·g^-1. The removal process is driven by electrostatic attraction, chemical reduction, and chelation, with the beads acting as catalysts to convert toxic Cr(VI) into less toxic Cr(III). The PLCB structure enhances usability, facilitates superior recyclability, and maintains adsorption efficiency over multiple cycles. This study presents an efficient and scalable strategy for producing high-performance biomass-based adsorbents with significant potential for industrial wastewater treatment while offering an additional catalytic function for Cr(VI) detoxification.