Advances in bio-based composites for soil heavy metal remediation: a comprehensive review

This review explores the potential of natural material-derived composites to remediate toxic element contamination in terrestrial environments. It highlights innovative synthesis strategies-such as chemical modification, nanomaterial incorporation, and physical processing-that produce porous structures with high adsorption capacities. Key mechanisms including ion exchange, surface complexation, biomineralization, and photocatalysis are examined for their roles in immobilizing hazardous ions. Renewable feedstocks like agricultural residues, lignocellulosic biomass, and marine-derived polymers are evaluated as sustainable precursors. The integration of these materials with plant-assisted uptake and microbial stabilization is also discussed to enhance remediation performance. Kinetic modeling, adsorption isotherms, and regeneration studies provide insights into material efficiency, while life cycle assessments emphasize the environmental benefits of green synthesis and circular economy practices. Challenges such as scalability, feedstock variability, and long-term performance are addressed, and future research directions are proposed to optimize material design and expand real-world applications. This review bridges mechanistic insight with practical solutions, offering a foundation for sustainable technologies that mitigate environmental toxicity and support ecological resilience.