An identification of arsenic retention mechanisms in column filtration systems packed with limestone

Abstract

The high concentrations of arsenic in the groundwater of Zimapán, Hidalgo, Mexico, have led to the search for options that contribute to resolving this problem. In this study, we use percolation columns to remove arsenic in aqueous solutions in coexistence with ions such as fluorides, chlorides, sulfates, or bicarbonates. This filtration technique is effective and low cost since the filter material is a native limestone belonging to the Soyatal Formation of the Upper Cretaceous. This article characterizes the mechanisms of arsenic removal by calcite, the limestone's main constituent, through X-ray absorption spectroscopy (XAS). The main processes of arsenic retention in calcite are adsorption (forming corner-sharing inner-sphere surface complexes) and coprecipitation (replacing AsO4 in the carbonate site).