Preparation and characterization of calcium treated bentonite clay and its application for the removal of lead and cadmium ions: Adsorption and thermodynamic modeling

Bentonite clay is an effective adsorbent for decontamination and treatment of wastewater containing dangerous metal ions. In this study, natural and calcium calcined bentonite clay (CCBC) were investigated for the elimination of Lead (Pb2+) and Cadmium (Cd2+) ions from wastewater. BET-N-2, X-ray diffraction and Zero point charge were used to examine the texture properties. Adsorption, equilibrium and kinetic data were experimentally obtained and modelled. Langmuir, Freundlich, Sips, Redlich-Peterson, Toth, Temkin and Dubinin Raduskevick models were fitted to experimental isotherms. The Langmuir model shows better representation of the isotherms data for Pb ions and Dubinin Raduskevick is better for Cd ions. The Results obtained allowed to conclude that the kinetic data was better represented by the pseudo second-order model for lead and cadmium adsorption. The AG negative values obtained for Pb2+ and Cd2+ adsorption onto clay confirm the spontaneous nature of the process. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.