Potential of Bentonite Clay for Heavy Metal Immobilization in Soil

Abstract

A montmorillonite rich bentonite clay was evaluated for heavy metals (Cu and Zn) removal from aqueous system and its immobilization efficiency of the metals in soil by batch adsorption experiment. The effect of adsorbent amount, pH and initial concentration of metals on the extent of adsorption was investigated. The adsorption data were fitted with Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms. The maximum monolayer adsorption capacity of bentonite was obtained from Langmuir adsorption isotherm and its values are 13.95 mg g−1and 11.41 mg g−1 for Cu (II) and Zn (II), respectively. The maximum monolayer adsorption capacity of the soil increased from 1.39 mg g−1 to 11.76 mg g−1 and 0.42 mg g−1 to 10.50 mg g−1 for Cu (II) and Zn (II), respectively, on addition of bentonite. The study demonstrates that bentonite has potential to remove Cu (II) and Ni (II) ions from aqueous solution and also from heavy metal polluted soil.