Evaluation of Bulgarian clinoptilolite as ion-exchanger for Cs+ removal from water solutions

The effect of irradiation on the Cs, Co and Eu-removal from aqueous solutions using Greek minerals

Sorption properties of Greek bentonites and zeolites were investigated in raw form and after irradiation for removal of Cs, Co and Eu from aqueous solutions using 137Cs, 60Co and 152Eu as tracers and γ-spectroscopy. The sorption experiments were undertaken under different conditions (pH, concentration, competitive ions and temperature). The structural changes of the sorbents due to irradiation and metal sorption were examined through XRD, FTIR and SEM/EDS. Sorption isotherms were reproduced by mathematical models and thermodynamic parameters were derived. The results showed that the sorption capacity was slightly affected by irradiation. The environmental compatibility tests proved the safe disposal of the investigated materials.

Adsorption characteristics of a clinoptilolite-rich zeolite compound for Sr and Cs

The Sr and Cs adsorption capacities of LithoFill™, LithoGran™ and a competing clinoptilolite containing zeolite product were investigated by radioanalytical methods (⁸⁵Sr and ¹³⁴Cs gamma spectroscopy). The dependence of adsorption and adsorption rate on physical factors including temperature, available ions and time were assessed. In addition, the reversibility of adsorption under high ionic strength conditions was also examined. In general, cesium is more strongly adsorbed than strontium, adsorption yields are generally independent of temperature (from room temperature to 65 °C) and adsorption is relatively rapid (identical results for 2 or 5 day adsorption times). As expected, increasing the concentration of other ions in solution tends to reduce adsorption of cesium and strontium. In general, Cs adsorption ranges between 54.5 and 45.2 mg/g for LitoFill and LitoGran samples and between 36.9 and 24.4 mg/g for the competing product. For Sr adsorption, ranges are 30-21 mg/g and 7.3-6.7 mg/g respectively, leading to the conclusion that the higher content of clinoptilolite in the LitoFill/LitoGran samples results in better adsorption characteristics.