PNNL

Abstract

This study explores the hydration and transport properties of aqueous cesium hydroxide (CsOH) solution, with or without 1 molar (M) sodium nitrite (NaNO2). Historic studies indicate that Cs+ ions decrease viscosity and increase diffusion rates, whereas OH- ions have the opposite effect. Here, the influence of OH- was dominant in CsOH solutions, leading to increased viscosity and reduced diffusion rates. There was a linear relationship between diffusion coefficients and water activity, emphasizing the significant role of ion-water interactions in determining transport properties. This may be because the interaction between Cs+ and the anions is weak even when they are in direct contact with each other. The weakness of the ion-pairing was established through thermodynamic analysis. The findings suggest that ion-pairing is not the only important interaction controlling transport properties when ion-pairing is weak. Nonetheless, ion-pairing or obstructions did result in more sluggish transport properties as electrolyte concentrations increased. Overall, the research enhances the understanding of the complexities underlying ion interactions in multicomponent solutions.