Engineered Biopolymer Architectures for Selective Metal Ions Extraction

ABSTRACT The separation and recovery of metal ions from industrial and municipal wastewaters and leachates is essential for environmental sustainability and resource conservation. Bio‐based polysaccharides, such as cellulose and chitin; proteins, such as keratin; and other biomacromolecules, such as lignin, offer a promising, sustainable alternative to conventional adsorbents due to their abundance, renewability, and inherent presence of metal‐binding functional groups. This review explores strategies to engineer these materials and enhance their metal interaction capabilities. These include chemical modifications (e.g., introduction of charged groups and metal‐specific ligands), physical treatments (e.g., particle size reduction and porosity control), and the development of composite materials and advanced architectures, such as activated carbons, membranes, fibers, and 3D‐printed structures. Despite their potential, challenges such as natural variability, lower durability compared to synthetic materials, and economic considerations remain. Through targeted research and development, biopolymers could become viable, eco‐friendly solutions for hydrometallurgical metal recovery processes, aligning with circular economy principles. This review provides a comprehensive, mechanism‐oriented synthesis that integrates material classes, functionalization strategies, and adsorption selectivity trends relevant to metal recovery under hydrometallurgical conditions and outlines future directions to overcome existing barriers.