Biosorption of Heavy Metals Using Biomass-Derived Adsorbents: Mechanisms, Modifications, and Future Perspectives

Heavy metals (HMs) pollution of water is a severe global challenge. This review uniquely synthesizes recent advances in using processed agricultural and industrial biomass wastes as low-cost, eco-friendly adsorbents specifically targeting nickel, cobalt, and chromium removal. We systematically analyze how simple chemical and physical treatments significantly enhance metal-binding capacities, often achieving near-complete removal in laboratory settings. Furthermore, emerging bio-nanocomposites combining biomass with metal oxides demonstrate superior multifunctional performance. Crucially, this work integrates detailed discussions on adsorption mechanisms, isotherms, kinetics, thermodynamics, and regeneration strategies through comprehensive tables and schematic diagrams, offering a holistic framework that has not been previously compiled. Despite promising lab-scale results, translating these materials to real-world water treatment faces major challenges including scalable production, complex wastewater interactions, and adsorbent recovery. Addressing these requires interdisciplinary research focused on scalable engineering, cost-effective regeneration, and full environmental impact assessments. By bridging fundamental biosorption science with practical application barriers, this review provides timely, impactful insights to guide future research and promote sustainable water remediation technologies.