Sorption of lead on Iranian bentonite and zeolite: kinetics and isotherms

This study deals with the use of the natural, low-cost sorbents bentonite and zeolite for the removal of lead from aqueous solutions. The mineral material is from large deposits of bentonite and zeolite that have been discovered recently in Iran. Experimental and modeling data from our kinetic and equilibrium investigations reveal that (1) the pseudo-second-order kinetic model gave the best fit, and (2) the Koble-Corrigan sorption model describes the interaction between Pb(II) and the two mineral materials better than the Freundlich and Langmuir models. However, the sorption of Pb(II) ions by zeolite and bentonite is complex and probably involves several mechanisms. The experimental data show that natural zeolite and bentonite used in this study exhibited a reasonable sorption capacity for Pb(II), and thus may be useful for the immobilization of Pb(II) from polluted sites.