152/154Eu(III) Ions Sorption on Stannic Silicate Granules: A Radiotracer Study

Abstract

Silicates and related porous materials are solids able to interact with guest molecules, ions and atoms not only at their surfaces but also within the bulk. With the objective of producing materials showing better sorption properties, a laboratory prepared stannic silicate in mixed SnO 2 @SiO 2 form was investigated as potential sorbent for retention of long lived radionuclides 152+154 Eu 3+ from aqueous solution containing 134 Cs + and 60 Co 2+. Sorption of Eu 3+ has been reported as a function of contact time, initial ion concentration and temperatureat a constant pH equal to 4. The uptake of Eu 3+ was found to be favored at high ion concentration, high temperature and no significant sorption took place after the first 4 h. A pseudo second order kinetic pattern fitted the sorption data well, while equilibrium was positively verified with Freundlich-type equation. Further, in attempt to enhance the separation efficiency of the studied radionuclides from aqueous medium, results showed that the sorption on SnSi was found strongly temperature-dependent. Ions equilibrium was found exothermic in case of 134 Cs + however it endothermic in case of both 60 Co and 134 Cs ions. Based on this contradict uptake, selectivity of ions has been estimated and separation of Eu 3+ from other competing ions was achieved.The thermodynamic parameters (∆G•, ∆H• and ∆S•) showed that the adsorption process is spontaneous and exothermic in case of 134 Cs + but it endothermic in case of the later studied ions.