nanomaterials for environmental remediation: classification, mechanistic insights, and applications in water, soil, and air pollution control

Environmental pollution remains a critical global challenge that threatens ecosystems, public health, and sustainable development. conventional remediation technologies often suffer from high operational costs, limited efficiency, and risk of secondary pollution. nanotechnology has emerged as a promising strategy for environmental remediation due to the exceptional reactivity and functional adaptability of nanomaterials. various classes of nanomaterials, including metal and metal oxide nanoparticles, carbon-based nanostructures, polymeric nanocomposites, magnetic nanoparticles, semiconductor materials, and bioinspired nanomaterials, have demonstrated significant potential for the removal of toxic and emerging contaminants from water, soil, and air. this review systematically discusses the classification of nanomaterials, their fundamental remediation mechanisms, and applications across environmental compartments. the key mechanisms include adsorption, photocatalytic degradation, redox transformation, membrane-assisted separation, and magnetic recovery. emphasis is placed on green synthesis approaches aimed at improving environmental compatibility and reducing production-related risks. recent advances in hybrid nanocomposites, smart and stimuli-responsive systems, and ai-integrated nanosystems for real-time monitoring have been highlighted. despite considerable progress, challenges, such as nanotoxicity, environmental persistence, regulatory constraints, and scale-up limitations, remain barriers to large-scale implementation. therefore, future research should focus on developing safer, cost-effective, and scalable nanomaterial-based technologies to ensure sustainable and practical environmental remediation.