Multifunctional Hydrogel‐Nanomaterial Composites for Chemical and Biological Contaminant Remediation: A Review Article

Nanocomposite hydrogels, three‐dimensional polymer networks integrated with functional nanomaterials, have emerged as versatile platforms for environmental remediation due to their high water affinity, tunable physicochemical properties, and synergistic multifunctionality. This review offers a comprehensive evaluation of hydrogel nanomaterial composites for the removal of both chemical and biological contaminants, with a particular emphasis on water purification and pathogen inactivation. Key synthesis strategies, including chemical, physical, and radiation‐induced crosslinking, are critically evaluated alongside functionalization approaches involving reactive functional groups (carboxyl, amine, thiol, sulfonic) and nanomaterial incorporation (carbon‐based materials, MXenes, metal oxides, metal–organic frameworks, and plasmonic or magnetic nanoparticles). These modifications enhance pollutant selectivity, mechanical stability, and reusability. Fundamental removal mechanisms, including adsorption, ion exchange, chelation, photocatalysis, antimicrobial activity, and photothermal inactivation, are systematically discussed for applications ranging from heavy‐metal and organic‐pollutant capture to bacterial, viral, and fungal disinfection. Despite significant progress, challenges related to long‐term environmental stability, scalability, real wastewater performance, and lack of standardized testing protocols remain. Future research should prioritize green synthesis, techno‐economic feasibility, life‐cycle assessment, and the development of smart, stimuli‐responsive hydrogel nanomaterial composites for sustainable water and air remediation.