Nanomaterials for Environmental Pollutant Remediation: Classification, Synthesis Pathways, Mechanisms, and Applications

Rapid industrialization, agricultural intensification, and urban expansion have contributed substantially to the widespread contamination of water, soil, and air, posing serious threats to environmental sustainability, ecosystem integrity, and human health.Conventional remediation technologies are often constraine d by high operational costs, limited removal efficiency for certain contaminants, and the generation of secondary waste.In this context, nanomaterials (NMs) have emerged as promising alternatives for environmental remediation owing to their high surface-area-to-volume ratios, tunable physicochemical characteristics, and enhanced surface reactivity.This review critically examines recent advances in nanotechnology-enabled environmental remediation, with particular emphasis on the classification, synthesis, functional mechanisms, and practical applications of diverse nanomaterials.Major categories include inorganic nanomaterials (metal and metal oxide nanoparticles, bimetallic nanostructures, and nanoclays), carbon-based nanomaterials (carbon nanotubes, graphene derivatives, fullerenes, and carbon quantum dots), organic and polymeric nanomaterials (cellulosebased nanostructures, chitosan, and dendrimers), and hybrid nanocomposite systems, including metal -organic frameworks and nanocomposite membranes.Their respective advantages, limitations, and pollutant-specific remediation capabilities are systematically evaluated.Furthermore, conventional physical and chemical synthesis approaches are compared with emerging green and biologically mediated synthesis stra tegies, highlighting their environmental implications and potential for sustainable production.The principal mechanisms governing pollutant removal and transformation, including adsorption, membrane -based separation, photocatalytic degradation, chemical oxidation-reduction, and antimicrobial disinfection, are comprehensively discussed.Particular attention is given to the challenges associated with large -scale implementation, nanomaterial stability and recovery, potential ecotoxicological risks, economic feasibility, and evolving regulatory requirements.Finally, future research priorities are identified, emphasizing the development of environmentally benign synthesis methods, scalable and cost-effective remediation technologies, standardized performance evaluation protocols, and comprehensive life-cycle assessments.Collectively, this review provides an integrated perspective on the opportunities and limitations of nanotechnology-based remediation and highlights critical research directions for translating laboratory-scale innovations into environmentally sustainable, field-applicable solutions.