Recent advances in modified nanoscale zero-valent iron for petroleum hydrocarbons and heavy metal remediation

The co-occurrence of petroleum hydrocarbons (PHs) and heavy metals in contaminated soils presents a complex remediation challenge where traditional methods often fail due to high costs, limited efficacy, and potential secondary pollution. Nanoscale zero-valent iron (nZVI) has emerged as a promising alternative, leveraging its core-shell structure and dual functionality in both reductive degradation and immobilization processes. However, bare nZVI suffers from rapid aggregation, surface passivation, and short reactive lifespans. This review critically examines advanced modification strategies, including polymer stabilization, sulfidation, carbonaceous supports, and bimetallic doping, to enhance nZVI's mobility, longevity, and selectivity. We provide mechanistic insights into contaminant removal pathways and synthesize field-scale performance data, offering a unique perspective on the environmental trade-offs and field-scale deployability challenges often overlooked in laboratory studies. By integrating current advances with a critical analysis of remaining bottlenecks, this work provides a framework for optimizing modified nZVI systems to bridge the gap between laboratory promise and sustainable, field-scale remediation of complex contaminant mixtures.