Influence of Thermal Treatment on Bentonite Used as Adsorbent for Cd, Pb, Zn Retention from Mono-Solute and Poly-Solute Aqueous Solutions

The retentions of Zn, Cd and Pb cations by one treated bentonite up to 750 degrees C were analyzed. The retentions were evaluated by using mono-and poly-solute aqueous solutions of such cations. The adsorptions were carried out in batch system at room temperature. The solid/liquid ratio was 2% wt.v(-1). The solids were characterized by X-ray diffraction, thermal and chemical analyses. The Zn cation from mono-or polysolute-solutions was retained in higher amount than Cd and Pb cations in similar solution types by bentonite. The retentions were effective up to 450 degrees C calcined bentonite, after that, the retention capacity decreased in concordance with dehydroxylation of the structure of clay minerals.