Removal of Cs from aqueous solutions by perlite.

Perlite is an abundant mineral that requires minimum processing before use either as raw or expanded perlite, resulting in a low-cost, natural porous material. The application of materials for the removal of radioactive cesium from liquid effluents and contaminated waters is currently of great interest. Perlite has been evaluated in the last years for the sorption of a variety of metals, but it had not been investigated before for removal of Cs from contaminated waters. The present work examines the use of perlites from a deposit in Salta, Argentina, for removal of Cs from aqueous solutions. The mineral was characterized by means of powder X-ray diffraction, thermal analysis, analysis of specific area, and scanning electron microscopy. The effect of solution pH, presence of concomitant ions, contact time, Cs initial concentration, perlite dose, and basic or acidic treatment of the sorbent were studied by batch experiments. Removal increased at high pHs and after treatment with NaOH. Sorption of Cs by perlite presented a rapid rise in the first 80 min of contact. The selected material (from Pava mine) yielded removal efficiencies of 84 and 89% before and after treatment with NaOH, respectively, for a dose of 30 g perlite/L and initial cation concentration of 10 mg/L. Our results demonstrate that perlite is a material capable of removing Cs from aqueous solutions, even when applied at low doses. These findings are relevant in the context of removal of radioactive Cs isotopes from nuclear effluents and in case of contamination of environmental waters.