Transport equations for concentrated electrolyte solutions: Reference frame, mutual diffusion

Abstract

Transport coefficients of dissociated electrolytes in aqueous solution are studied in the framework of the primitive model of ionic solutions in which the solvent is a dielectric continuum. Simple explicit expressions are obtained by using a combination of Smoluchowski equation for the dynamics and the mean spherical approximation (MSA) for the equilibrium pair correlation function. The case of symmetrical and dissymmetrical electrolytes is examined. In the case of the mutual diffusion, a reference-frame correction, that can be obtained from density measurements has to be taken into account for molar concentrations. The combined Smoluchowski/MSA theory of the primitive model is found to be self-consistent since it is able to describe simultaneously the different transport and equilibrium properties up to high concentrations (1–2 mol l⁻¹).