THE REMOVAL OF HEAVY METAL IONS (COPPER, ZINC, NICKEL AND COBALT) BY NATURAL BENTONITE

Abstract

The removal of Copper (Cu2+), Zinc (Zn2+), Nickel (Ni2+) and Cobalt (Co2+) from aqueous solutions by adsorption onto natural bentonite was investigated. Experiments were carried out as a function of shaking time, temperature of solution and thermal treatment of bentonite. The kinetic processes of metal ions adsorption on bentonite were described by applying pseudo-first order and pseudo-second order rate equations. The pseudo-second order reaction rate model was found to describe best the kinetic data. The thermodynamic parameters (ΔH, ΔS and ΔG) for Copper (Cu2+), Zinc (Zn2+), Nickel (Ni2+) and Cobalt (Co2+) adsorption onto bentonite were also determined from the temperature dependence. The adsorption was endothermic reactions for Copper (Cu2+) and Zinc (Zn2+), and exothermic for Nickel (Ni2+) and Cobalt (Co2+). The results suggested that natural bentonite is suitable as an adsorbent material for adsorption of metal ions from aqueous solutions.