Tracer Diffusion in Colloidal Mixtures

Results for the long-time tracer-diffusion coefficients, from two different theoretical approaches describing tracer diffusion in colloidal mixtures, are presented. The systems studied are binary mixtures of charged colloidal particles interacting through Yukawa-type pair potentials. The effect of bidispersity when different parameters of both species (charges, diameters, relative concentrations, etc.) are varied is discussed. In both theories, the single-exponential approximation and the Fick plus decoupling approximation, the relevant quantities describing tracer diffusion at long times, are expressed in terms of integrals of the static structural properties and the pair interparticle potentials of the system. The input static correlation functions are calculated within the extended rescaled mean spherical approximation for Derjaguin-Landau-Verwey-Overbeek interactions. In general, both theories predict similar trends for the tracer-diffusion coefficients as the charge, size, and relative concentration parameters are varied. © 1995 Academic Press. All rights reserved.

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