Issue 6, 2025

Construction of clay-mediated nZVI composites to alleviate the decline in Cr(vi) removal during co-transport with humic acid and phosphate

Abstract

The natural presence of phosphate and humic acid (HA) may impact the removal of Cr(VI) by green synthesized clay-supported nano-zero-valent iron (nZVI@GT) composites. This triggers the investigation of Cr speciation transformation by M-nZVI@GT and K-nZVI@GT, prepared with nZVI@GT loaded on montmorillonite and kaolinite clays. The Cr(VI) removal with the existence of phosphate and HA was investigated during cotransport in water-saturated sand columns. This study revealed that M-nZVI@GT exhibited a higher Cr(VI) removal capacity (82.08 mg g−1) than K-nZVI@GT (61.74 mg g−1). However, phosphate showed stronger competition with Cr(VI) for adsorption on the single-layer structured M-nZVI@GT, reducing its removal capacity to 61.98 mg g−1 and inhibiting Fe0 core corrosion compared to the lamellar-structured K-nZVI@GT. Notably, phosphate enhanced the electrostatic repulsion between M-nZVI@GT and quartz sand, facilitating the mobility of M-nZVI@GT in the sand porous media (increasing from 41.03% to 52.20%). This enhancement was associated with a higher k1d/k1 value, which increased from 0.691 to 0.830. In particular, due to its steric hindrance of macromolecules, less HA entered the lamellar structure of K-nZVI@GT, lowering competitive adsorption with Cr(VI) for active sites. This research's findings indicate that K-nZVI@GT, as an environmentally friendly remediation material, can successfully alleviate the inhibitory effects of HA on Cr(VI) removal in contaminated soil. This study highlights the distinct structural construction of Fe-based nanomaterials via different clay meditations to improve the practical application of nanotechnology for soil in situ remediation.

Graphical abstract: Construction of clay-mediated nZVI composites to alleviate the decline in Cr(vi) removal during co-transport with humic acid and phosphate

Supplementary files

Article information

Article type
Paper
Submitted
18 Feb 2025
Accepted
02 May 2025
First published
02 May 2025

Environ. Sci.: Nano, 2025,12, 3317-3328

Construction of clay-mediated nZVI composites to alleviate the decline in Cr(VI) removal during co-transport with humic acid and phosphate

W. Jiang, N. Xu, W. Sun and F. Du, Environ. Sci.: Nano, 2025, 12, 3317 DOI: 10.1039/D5EN00185D

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