Recent advances in the synthesis of MOF-based composites for heavy-metal ion adsorption

With rapid industrialization, the industrial wastewater discharge has increased considerably. Treating large volumes of wastewater containing heavy metals is challenging. Heavy metals pose significant risks to human health and various ecosystems owing to their high toxicity and resistance to degradation. A fast, efficient, and economical method for removing heavy metals is adsorption. Metal-organic frameworks (MOFs) have garnered significant attention as adsorbent materials owing to their high specific surface area, tunable pore size, and ease of modification. This review examines the advantages and limitations of traditional MOFs, and presents a comprehensive summary of composites developed to overcome these limitations. Further, the review highlights recent advancements in composite materials, including metal oxides, sulfides, chitosan, and hydrogels, and their role in enhancing the adsorption process. In addition, this review discusses the stability and key synthesis steps of each composite material, providing insights into their respective advantages and challenges. The challenges faced by MOF-based composites are analyzed and synthesis methods that facilitate improved performance and increased scope of application in wastewater treatment are recommended.