Insights into the role of FeP 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.