Occlusion and Ion Exchange in the Molten (Lithium Chloride + Potassium Chloride + Alkaline-Earth Chloride) Salt + Zeolite 4A System with Alkaline-Earth Chlorides of Calcium and Strontium and in the Molten (Lithium Chloride + Potassium Chloride + Acti

摘要

The interaction between molten salts of the type LiCl-KCl-MeCl_n (Me = Ca, Sr, U; x_(MeCl_n) = 0 to 0.45; and x_(KCl)/x_(LiCl) = 0.69) and zeolite 4A have been studied at 823 K. The main interactions between these salts and zeolite are molten salt occlusion to form salt-loaded zeolite and ion exchange between the molten salt and salt-loaded zeolite. An irreversible chemical reaction has been observed in the LiCl-KCl-UCl_3 + zeolite system. The extent of occlusion is a function of the concentration of MeCl_n in the zeolite and is equal to 10 +- 1 Cl~- per zeolite unit cell, (AlSiO_4)_(12), at infinite MeCl_n dilution. The ion-exchange mole-fraction equilibrium constants (separation factors) with respect to Li are decreasing functions of the concentration of SrCl_2 and UCl_3, but an increasing function of the concentration of CaCl_2 in the zeolite. At infinite MeCl_n dilution, they are equal to 0.9, 11.9, and 13 for CaCl_2, SrCl_2, and UCl_3, respectively. The standard ion-exchange chemical potentials are equal to -50.0, -84, and - 101.1 kJ centre dot mol~(-1) for Ca~(2+), Sr~(2+), and U~(3+), respectively.