Sorption mechanisms and materials for mitigating heavy metal contamination in soil and water systems - A review

Abstract

Heavy metal contamination in soil and water systems represents a persistent environmental challenge due to the non-degradable nature, toxicity, and bioaccumulative behavior of metallic pollutants. Sorption-based remediation has emerged as a widely applied and adaptable approach for reducing metal mobility, bioavailability, and ecological risk across diverse environmental settings. This review critically examines recent advances in sorption mechanisms, materials, modeling approaches, and field applications for minimizing heavy metal contamination. Key sorption processes, including ion exchange, surface complexation, electrostatic attraction, precipitation, and redox transformations, are discussed in relation to metal speciation and environmental conditions. The performance of natural sorbents, biochar and carbon-based materials, and engineered and nanostructured sorbents is evaluated, with emphasis on their advantages, limitations, and suitability for soil and water remediation. Progress in sorption modeling and kinetics is reviewed to highlight the role of equilibrium isotherms, kinetic models, and mechanistic frameworks in predicting system behavior and supporting scale-up. Field applications demonstrate the practical potential of sorption technologies but also reveal challenges associated with material stability, competitive sorption, long-term effectiveness, and economic feasibility. Finally, future research directions are outlined, focusing on sustainable material development, integration of sorption with complementary remediation strategies, and improved translation of laboratory findings to real-world conditions. Overall, this review underscores the continued importance of sorption-based technologies in achieving effective and sustainable management of heavy metal contamination in soil and water environments.