Arsenic Adsorption on Fe-oxides mixed with Mn-oxides: Potential of Fe-Mn Nanocrystalline Coated Calcite Grains for Filtration of Arsenic Contaminated Drinking Water

Abstract

Arsenic water contamination is a worldwide problem, particularly in developing and underdeveloped countries. Nanocrystalline iron oxides are efficient at adsorption of arsenic, and many current purification devices use them as free particles or as coatings on silica. However, these methods are typically chemically unstable, costly, and/or difficult to deploy in impoverished and undereducated areas. Additionally, research shows that of the two primary arsenic species, ionized to (V) state and (III) state, As (V) species more readily adsorb on various iron oxides than As (III) species. This research utilizes a novel approach for oxidizing As (III) to As (V) with manganese (IV) oxides and subsequent sorption with Fe-oxide. It also explores the precipitation of Fe-oxides in the presence of calcite, for the potential of a nanoparticle Fe-oxide coated calcium carbonate system for future sorption use. A simple filter composed of an iron-coated limestone grain with manganese oxides could yield greater arsenic sorption from water, be easily deployed, and lead to the development of an effective and cost-efficient system for removing arsenic from drinking water.