Mechanisms of Synergistic Removal of Low Concentration As(V) by nZVI@Mg(OH)2 Nanocomposite

In this work, by using Mg(OH)(2) nanoplatelets as support material for nanoscale zerovalent iron (nZVI), riZVI@ Mg(OH)(2) composite was prepared and found to have super high adsorption ability toward As(V) at environmentally relevant concentrations. It was revealed that the variation of corrosion products of nZVI in the presence of Mg(OH)(2) and Mg2+ is an important factor for increase in the adsorption ability toward As(V). X-ray diffraction (XRD) analysis indicated that the weakly basic condition induced by Mg(OH)(2) decreases the lepidocrocite (gamma-FeOOH) and increases the magnetite/maghemite (Fe3O4/gamma-Fe2O3) content in the corrosion products of nZVI, and the latter has better adsorption affinity to As(V). Moreover, extended X-ray absorption fine structure spectroscopy (EXAFS) indicated that the coordination between arsenic and iron minerals is influenced by dissolved Mg2+, leading to probable formation of magnesium ferrite (MgFe2O4) which has considerable adsorption affinity to As(V). This work provides an important reference not only for the design of pollution control materials but also for understanding arsenic immobilization in natural environments with ubiquitous Mg2+ ion.