100‐Fold Reductivity Enhancement of Nanoscale Zero‐Valent Iron After 1‐Year Aging in Water via Regulating Corrosion Reactions

Abstract

ABSTRACT Nanoscale zero‐valent iron (nZVI) is the most promising reductant for in situ groundwater remediation, but its field application around the world is quite limited for decades, due to significant reductivity loss by water oxidation during long‐term (e.g., years) application. Herein, we report a polysiloxane(Fe)‐modified nZVI (PSO(Fe)‐nZVI, 269.0 ± 23.5 nm) featuring loosened hydrophobic C16 chains and Si─O groups on the surface and interior. Remarkably, after 420‐day aging in water, PSO(Fe)‐nZVI exhibits 102‐fold and 211‐fold enhancements of reduction rate constants for trichloroethylene and Cr(VI), respectively, 4‐order‐of‐magnitude higher than nZVI. The loosened C16 chains on PSO(Fe)‐nZVI could regulate Fe(0)→Fe(II) reaction in water to enhance specific surface area by 131 folds and expose more active Fe species. The Si─O groups could combine with Fe(II) and inhibit the Fe(II)→Fe(III) reaction to reserve 70.8% of active Fe species. This work highlights the regulation of corrosion reactions by surface engineering to boost the reduction performance of nZVI for long‐term groundwater remediation.