Adsorption characteristics of Cu (II) onto CaCl2 pretreated algerian bentonite

Abstract

Calcium treated bentonite clay (CTBC) was prepared by CaCl2 impregnation of Algerian bentonite clay. The prepared adsorbent was characterized and successfully used to remove Cu (II) ions from aqueous solutions at different conditions (pH, stirring time and initial copper concentration). Results showed that the raw bentonite was changed completely into Ca-bentonite, which exhibits a high adsorption capacity (qt = 19.98 mg g-1) at pH = 5.0. It appeared that the sorption mechanisms are simultaneous and strongly depend on pH value. In the pH range from 3-10, the removal of copper occurs mainly by ion exchange, surface metal complexation and precipitation of Cu (OH)2. It was also found that the experimental data of kinetic adsorption are well fitted by the pseudo-first order model. Equilibrium data obeyed the Langmuir isotherm with maximum adsorption capacity of 55.48 mg g-1. The mean adsorption energy predicted by Dubinin-Radushkevich model (E = 1.55 Kj/mol) shows the physical nature of the adsorption interactions. Results of this study suggest the potential of the prepared CTBC which can be used easily for fast decontamination of wastewater containing toxic metal ions.