Abstract
The present experiment was designed to prepare and examine the adsorption potential of Purple shale (PS), siltstone (SS) and nanocomposites of SS with zinc oxide (SS/ZnO) and magnetite nanoparticles (SS/MNPs) for As sequestration present in contaminated water at batch scale. The PS, SS, SS/ZnO, and SS/MNPs were characterized with different techniques. The effect of As initial concentrations (1.0-10.0 mg/L), material doses (1-4 g/L), interaction time (0-180 min), pH (3-10) and competing inorganic ions using groundwater samples was examined on the sequestration of As from contaminated aqueous media. The order of As sequestration by the as-synthesized materials was: SS/MNPs (98.9%-83%) > SS/ZnO (91.5%-95%) > SS (84.56-56.6%) > PS (81.3%-50%). Experimental results were simulated with kinetic and equilibrium adsorption isotherms models. Kinetic results were better explained with pseudo 2nd order model and equilibrium results fitted well with Freundlich model. The SS/ZnO and SS/MNPs showed excellent reusability as well as stability in five adsorption/desorption cycles. Presence of interfering ions in groundwater samples showed maximum decline (5.3%) by PS. It was concluded that impregnation of sedimentary material with promising nanotechnology is effective for decontamination of As-contaminated aqueous systems. (C) 2020 Elsevier B.V. All rights reserved.