Diffusion Coefficients for Dilute Liquids

Your objectives in studying this section are to be able to  

Estimate diffusion coefficients for binary dilute liquid systems using the Wilke and Chang equation. 

In contrast to the case for gases, where an advanced kinetic theory to explain molecular motion is available, theories of the structure of liquids and their transport characteristics are still inadequate to allow a rigorous treatment. Liquid diffusion coefficients are several orders of magnitude smaller than gas diffiisivities, and depend on concentration due to the changes in viscosity with concentration and changes in the degree of ideality of the solution. As the mole fraction of either component in a binary mixture approaches unity, the thermodynamic factor T approaches unity and the Fick diffusivity and the MS diffusivity are equal. The diffusion coefficients obtained under these conditions are the infinite dilution diffusion coefficients and are given the symbol TP. 

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Table 6.3-1. Diffusion Coefficients for Dilute Liquid Solutions... 

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