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Sorption mechanism of some radionuclides onto zircono-silicate as a cation exchanger

Mamdouh M.Abou-Mesalam

Zircono-silicate as inorganic ion exchanger was synthesized in two ratioÂÂ’s for Zr/Si to equal 0.4 and 1.0. Structure features for two ratioÂÂ’s were conducted and the molecular formulas of two synthesized ratioÂÂ’s was found, {(ZrO2) (H2SiO3)]1.58. 5.21H2O} and {(ZrO2) (H2SiO3)1.5. 7.88H2O} for samples I and II, respectively. Distribution coefficient studies of Cs+, Co2+ and Eu3+ ions on the matrices were carried out at different reaction temperatures. Thermodynamic parameters i.e. G, S and H have been calculated for the sorption system. The sorption process was found to be endothermic with the selectivity sequence, Eu3+>Co2+ > Cs+ for zircono-silicate I and Co2+>Eu3+>Cs+ for zircono-silicate II. Kinetic studies of exchange of Cs+, Co2+ and Eu3+ ions on zircono-silicate I and II was also investigated under particle diffusion control. The effective diffusion coefficients, activation energies and entropies of activation have been evaluated.