Regenerative Performance and Stability of Metal-Organic Frameworks following Heavy Metal Adsorption from Aqueous Solutions: A Mini Review

Metal-organic frameworks (MOFs) have attracted considerable research attention as a promising class of emerging adsorbents. MOFs possess exceptionally high surface areas, tunable pore structures and chemically tailored environments, making them well-suited for heavy metal selectivity. In this context, this review examines the regenerative performance and structural stability of pristine, functionalised, composite and MOF-derived materials following heavy metal adsorption. Across the reviewed studies, MOF-based systems generally exhibited favourable regenerative performance, particularly composite and selected functionalised systems, with losses in adsorption capacity typically below 10-15% after several cycles. These observations suggest that with appropriate MOF design, performance requirements for practical water treatment are attainable. Performance and stability depended mainly on the regeneration strategy and the type of MOF employed, particularly the framework composition, the metal node and the linker chemistry. Various regeneration techniques have been successfully reported, including chemical elution with acid or alkaline solutions, chelation-assisted desorption, electrochemically-assisted regeneration, photoregeneration and hybrid chemical-thermal strategies. Combined regeneration approaches showed strong potential to improve desorption efficiency while preserving structural integrity. MOF composites such as polymer-supported MOF beads, magnetic core-shell composites and MOF-oxide hybrid demonstrated enhanced recovery, stability and separation efficiency. Functionalisation with amines, thiols, sulfonates, and chelating agents improved selectivity in many systems. However, depending on the target metal, functionalisation can either facilitate or hinder regeneration due to strong coordination interactions. Despite these advances, most studies remain limited to batch-scale laboratory experiments with low regeneration cycles. Future work should prioritise increased regeneration cycles, leaching studies, stability evaluations, and continuous-flow systems to facilitate the practical implementation of MOF-based technology in water treatment.