Core–shell structured zero-valent manganese (ZVM): a novel nanoadsorbent for efficient removal of As(iii) and As(v) from drinking water

Abstract

This work describes the preparation of core–shell structured zero valent manganese (ZVM) for sequestration of total arsenic from drinking water. The material was synthesized using an ultra-sonication assisted hydrothermal route and the prepared material was characterized by using various analytical techniques such as FTIR, XRD, FE-SEM, EDS, AFM, TEM, TGA-DTA, BET and XPS. A combination of data shows successful fabrication of core–shell structured ZVM which consists of core zero-valent manganese (Mn⁰) encapsulated by layers of manganese oxides (Mn₃O₄–MnO₂). XPS analysis provides information regarding the surface interaction of arsenic species with the adsorbent material. The adsorbent was tested for arsenic removal with variation of the solution parameters in a batch technique. Both As(III) and As(V) could be removed over a wide pH range where the maximum sorption capacity was found to be 30.9 mg g⁻¹ and 72.5 mg g⁻¹ for As(III) and As(V), respectively. It was observed that the sorption kinetics and adsorption isotherm follow a pseudo second order kinetic model and D–R isotherm model, respectively. The presence of co-anions in a competitive environment had little effect on the arsenic removal properties of the material. Moreover, the exceptional arsenic adsorption capacity of ZVM in ground water and high reusability make it a promising adsorbent material in the removal of total arsenic from aqueous solution.