Insights into the role of FePX in phosphatized zero-valent iron for enhanced contaminant reduction

Zero-valent iron (ZVI) suffers from the limitations of unsustainable reactivity in remediation applications, resulting in the insufficient removal of contaminants. In this study, iron phosphides (FePX) modified ZVI (P-ZVI) was successfully synthesized using a simple ball-milling method. The degradation of various contaminants including Cr(VI), nitrate, p-chlorophenol, tetrabromobisphenol A and diatrizoate by P-ZVI was enhanced under anaerobic conditions, with the kinetic constants 1.14- to 5.23-fold higher than that of ZVI. P-ZVI exhibited superiorities for pollutant degradation over a wide pH range, after different aging time and during consecutive cycle experiments. Mechanistic explorations revealed that the incorporation of P into ZVI not only improved the electron transfer capability of ZVI but also promoted the accumulation of atomic hydrogen (H*), thus endowing P-ZVI with favorable reductive reactivity. Based on experimental analysis and density functional theory (DFT) calculation, FePX species on the surface of P-ZVI played a crucial role in H* stabilization by forming P-H* bonds and lowering H* adsorption energy. This study paves the way for future design and optimization of nZVI-based technology for the water decontamination.

Automated summary

In this study, iron phosphides modified zero-valent iron (P-ZVI) was synthesized using a simple ball-milling method, which showed enhanced degradation of various contaminants compared to ZVI. The incorporation of phosphorus improved the electron transfer capability of ZVI and promoted the accumulation of atomic hydrogen (H*), resulting in favorable reductive reactivity of P-ZVI. The FePX species on the surface of P-ZVI played a crucial role in stabilizing atomic hydrogen by forming P-H* bonds and lowering H* adsorption energy. This study provides insights for the design and optimization of nZVI-based technology for water decontamination.