Evaluation of diffusivities in electrolyte solutions using Stefan‐Maxwell equations

The Stefan‐Maxwell equations have been used to predict single‐electrolyte diffusion and ternary tracer diffusion in concentrated electrolyte solutions. Variations in diffusivity due to concentration have been shown to be related to the relaxation effect and viscosity changes of solution. Specific equations are presented to evaluate the ion‐ion and ion‐solvent interaction coefficients appearing in the Stefan‐Maxwell equations. These equations, when tested against experimental data, gave an accurate description of the process at up to 4.0 M concentrations and for trace species mobilities differing by a factor of ten.