Removal of heavy metals in water using nano zero-valent iron composites: A review

Heavy metals pollution has become a severe threat to human health and a challenging problem. Nano zero-valent iron (nZVI) has a unique core-shell structure. The core Fe0 has the reducing ability, and the iron oxide shell provides the reaction site, showing superior performance for heavy metals removal. This review summarized recent approaches to the modification of nZVI materials such as bimetal modification, sulfidation modification, surfactant modification and porous material supported nZVI. Then, the influence of environmental factors on the removal of heavy metals by nZVI composites and the mechanism (adsorption, reduction and oxidation mecha-nisms) were analyzed. And the application of the composite material in the permeable reactive barrier (PRB) and fluidized bed reactor (FBR). Finally, the requirements and challenges for applying nZVI-based composites were described to provide a basis for the future synthesis of green, efficient, and environmental-friendly materials.