Measurement of the Diffusivity of Cesium Ion in Aqueous Rubidium Chloride Solution

Abstract

For the first time cesium diffusivity in aqueous solutions of rubidium chloride is being reported here in the concentration range from 0.001 to 4.00 mol⋅dm−3. The measurement use a radioactive tracer technique employing a sliding cell mechanism. These diffusivity values were utilized to understand the transport mechanism of Cs ion in the RbCl–H2O system using the Onsager-Gosting-Harned equation and the extended Debye-Huckel equation. The observed deviation between the theoretical and experimental diffusivities are explained by introducing the concept of Field-Dielectric-Gradient forces and energies that exist around an ion, which takes care of the finite size of the ion, ion-water interaction and the ion-ion interaction in a continuum basis.