Nano Zero-Valent Iron Applications in Heavy Metal Remediation

Nano zero-valent iron (nZVI) has emerged as a versatile material for the rapid and cost-effective remediation of heavy metal contamination in water, soil and groundwater. Characterised by its high surface‐to‐volume ratio and strong reducing power, nZVI is capable of transforming toxic metal ions—such as hexavalent chromium, lead and cadmium—into less mobile or less toxic forms through a combination of reduction, sorption and co-precipitation processes. Practical deployment of bare nZVI, however, is often hindered by particle agglomeration, surface passivation and limited transport in porous media. To address these challenges, research has focused on stabilising nZVI via bimetallic formulations, supporting it on substrates such as biochar, bentonite or layered nanomaterials, and integrating it with Fenton‐like oxidative pathways. Such modifications can enhance colloidal stability, prolong reactivity, control release of iron species and improve contaminant removal under a wide pH range. These advances have enabled in situ application in permeable reactive barriers and ex situ treatment in engineered reactors. The global significance of nZVI stems from its low material cost, tunable surface chemistry and adaptability to diverse environmental matrices, offering a promising tool for sustainable management of heavy metal pollution.

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Nano Zero-Valent Iron Applications in Heavy Metal Remediation publication trend

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Technical terms

Nano Zero-Valent Iron (nZVI): Ultrafine iron particles in the zero oxidation state (Fe0) with a high surface area and strong reducing capacity, used to transform and immobilise contaminants.

Biochar: Carbon-rich material produced by pyrolysis of biomass; serves as a porous, functionalised support to disperse nanoparticles and enhance sorption.

Sorption: Collective term for the processes of adsorption (surface binding) and absorption (bulk uptake) by which contaminants adhere to a solid matrix.

Agglomeration: The undesired clustering of nanoparticles that reduces available surface area and limits reactive sites.

Passivation: Formation of an oxide or hydroxide layer on nZVI surfaces that diminishes electron transfer and slows contaminant reduction.

References

1. Removal of toxic elements from aqueous environments using nano zero-valent iron- and iron oxide-modified biochar: a review. Biochar (2022).
2. Application of nanoscale zero-valent iron in hexavalent chromium-contaminated soil: A review. Nanotechnology Reviews (2020).
3. Almond Shell-Derived, Biochar-Supported, Nano-Zero-Valent Iron Composite for Aqueous Hexavalent Chromium Removal: Performance and Mechanisms. Nanomaterials (2020).