Molecular dynamics study on the adsorption selectivity for negative elements in aluminosilicates

For the pyrochemical reprocessing of spent metallic nuclear fuels in molten salt baths it is important to investigate the adsorption selectivity of ca tions in aluminosilicates. A molecular dynamics simulation has been perform ed on sodalite and zeolite with exchangeable monovalent and multivalent cat ionic fission products at 673 K in order to calculate their self-diffusion coefficients in the aluminosilicate framework and estimate the selectivity of the exchangeable cations. The results enables us to conclude that the se lf-diffusion coefficients of monovalent cations decrease with increasing io nic radius. The order of the adsorption selectivity is Li < K < Na < Cs in sodalite and Li < Na < K < Cs in zeolite. The self-diffusion coefficients o f multivalent cations are almost independent of the ionic radius, and these cations are in aluminosilicates more stable than monovalent cations. The r esults are consistent with the experimental results.