Retention studies on arsenic from aqueous solutions by lime treated semi arid soils

Abstract

In this study, locally available semi-arid soils (Al-Ghat and Al-Qatif) having different chemical and mineralogical characteristics are considered as barrier materials, and their response to arsenic adsorption at varying initial concentrations, pH conditions, temperature and dilution ratios is studied. Empirical models (Langmuir and Freundlich) are applied to ascertain monolayer or heterogeneous adsorption. Lime is added to these soils in order to enhance their geotechnical properties. Kinetic models are employed to validate the type and nature of arsenic sorption onto these soils (whether pseudo first-order or second-order). Also Elovich and intraparticle diffusion models revealed that along with surface adsorption, chemisorptions and diffusion are the other processes occurring concurrently in the system, but it was not able to identify the dominant phenomenon among these models. It was concluded that both Al-Ghat and Al-Qatif soils when amended with lime can attenuate arsenic, and the experimental results correlate well with selected empirical models.