Graphene-supported nanoscale zero-valent iron: Removal of phosphorus from aqueous solution and mechanistic study

Abstract Excess phosphorusfrom non-point pollution sources is one of the key factors causing eutrophication in many lakes in China, so finding a cost-effective method to remove phosphorusfrom non-point pollution sources is very important for the health of the aqueous environment. Graphene was selected to support nanoscale zero-valent iron (nZVI) for phosphorusremoval from synthetic rainwater runoff in this article. Compared with nZVI supported on other porous materials, graphene-supported nZVI (G-nZVI) could remove phosphorusmore efficiently. The amount of nZVI in G-nZVI was an important factor in the removal of phosphorusby G-nZVI, and G-nZVI with 20 wt.% nZVI (20% G-nZVI) could remove phosphorusmost efficiently. The nZVI was very stable and could disperse very well on graphene, as characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS), Fourier Transform infrared spectroscopy (FT-IR) and Raman spectroscopy were used to elucidate the reaction process, and the results indicated that Fe-O-P was formed after phosphoruswas adsorbed by G-nZVI. The results obtained from X-ray diffraction (XRD) indicated that the reaction product between nZVI supported on graphene and phosphoruswas Fe 3 (PO 4 ) 2 ·8H 2 O ( Vivianite). It was confirmed that the specific reaction mechanism for the removal of phosphoruswith nZVI or G-nZVI was mainly due to chemical reaction between nZVI and phosphorus.