Removal of heavy metal ions from aqueous solutions by adsorption on magadiite

Removal of Cd(II), Zn(II) and Cu(II) from aqueous solutions using the adsorption process on magadiite has been investigated. It was found that the removal percentage of metal cations at equilibrium increases with increasing temperature, and follows the order of Cd(II)>Cu(II)>Zn(II). Equilibrium modeling of adsorption showed that the adsorptions of Cd(II), Cu(II), and Zn(II) were fitted to Langmuir isotherm. Kinetic modeling of the adsorption showed that first order reversible kinetic model fitted to experimental data. From kinetic model and equilibrium data, the overall rate constant (k) and the equilibrium constant (K) for the adsorption process were calculated. The overall rates of adsorption of metal ions follow the order of Cd(II)>Cu(I)>Zn(II). From the results of thermodynamic analysis, standard Gibbs free energy (Delta G degrees), standard enthalpy (Delta H degrees), and standard entropy (Delta S degrees) of adsorption process were calculated.