Hydration and transport properties of cesium hydroxide and mixed cesium hydroxide–sodium nitrite aqueous solutions

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 of electrolyte solutions 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.