Transforming soil decontamination: the role and prospects of nanotechnological remediation.

Soil pollution, driven by industrialization and intensive agriculture, poses critical risks and global threats, with over 16% of global soils estimated to be contaminated by heavy metals, organic pollutants, and pesticides. This is impacting ecosystems, food security, and human health through bioaccumulation and carcinogenicity. Conventional remediation methods are often costly, destructive, and insufficient for deep and heterogenous contamination, often generating secondary waste and require long time for treatment. Nanotechnology introduces a paradigm shift, leveraging nanomaterials with high surface area, tunable reactivities, and targeted delivery capabilities, offering rapid, versatile, and potentially sustainable in situ remediation. Nanoremediation mechanisms includes adsorption and immobilization, chemical reduction and degradation, catalytic and photocatalytic degradation, nano-enhanced bioremediation and phytoremediation. Key NM includes nZVI, FeO, doped TiO2, carbon nanotubes, graphene oxide, dendrimers, and nanobubbles, each tailored for specific contaminants and remediation strategies. Advances in green synthesis, surface functionalization, and delivery methods such as colloidal suspensions, electrokinetic injection addresses the challenge of NM scalability, mobility, and specificity in complex soil. Field-scale applications, in situ injection and nano-enhanced PRBs, demonstrate significant reduction in contaminant concentration and remediation times, though scalability and cost-benefit analyses remain ongoing. However, concerns about NM ecotoxicity, fate, and long-term environmental impacts necessitate comprehensive risk assessment, LCA, and robust regulatory frameworks. Nanotechnology offers transformative potential for soil remediation, with demonstrated efficacy in pollutant removal and process efficiency. Future researchers must focus on smart, sustainable NM design, predictive modelling, long-term field studies, and public engagement to ensure safe, effective, and widely accepted deployment of NMs. Despite growing body of the literature on NM-based remediation, majority of the existing studies are confined to aqueous batch system and controlled laboratory setups. Field scale investigations conducted under authentic soil conditions are scarce. This disparity limits direct translation of mechanistic findings in real-world soil decontamination conditions. Consequently, future research studies must prioritize validated soil column studies, pilot-scale trials, and in situ field studies for bridging gap between theoretical potential and practical applications. This review fills critical and long-standing gap by providing actionable, visually guided, and quantitatively supported information in a single data-rich document, satisfying the scope for transformative and interdisciplinary research.