Open-end capillary method in tracer and mutual diffusion of electrolyte solutions

Abstract

In this study, we derive the general solution of the diffusion equation for multicomponent systems, even with non-constant diffusion coefficients, in the case of limiting conditions corresponding to the open-end capillary method.

For this purpose, it was necessary to obtain the complete expression of the diffusion coefficients D_ij by a detailed analysis of the diffusion processes in an electrolyte solution in the framework of irreversible thermodynamics.

We show for some particular examples that these methods are powerful in the derivation of the phenomenological coefficients L_ij and D_ij from experimental measurements; and that the coupling will induce transient concentration gradients for initially homogeneous species.