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T.LOFLIN AND E.MCLAUGHLIN
Diffusion in Binary Liquid Mixtures by T. Loflin and E. McLaughlin1.2 Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana
(Received July 31, 1068)
Several expressionspreviously proposed for the mutual diffusion coefficient of a binary liquid system are shown to follow from the Bearman theory when a geometric-mean relationship between certain friction coefficients is assumed. The Rice-Allnatt extension of the Rice-Kirkwood theory, which can be tested without the introduction of this assumption, is shown to give virtually quantitative agreement with experiment for both viscosity and diffusion when the binary system is close to ideality. TJnder these conditions, however, their equations likewise approximate closely to the assumption of a geometric-mean relationship between the friction constants.
I. Introduction I n the study of the transport properties of mixtures of dense fluids, considerable effort has been devoted to the coefficient of mutual diffusion, D,from both the experimental3 and the theoretical points of view. On the theoretical side a number of equations have been proposed relating the mutual diffusion coefficient to other properties of the mixture. It is the purpose of the present article to show a common route t o the derivation of these equations which have, as a necessary condition for validity, a geometric-mean relationship between certain friction coefficients. I n addition a check is made on the recent theory of Rice and Allnatt4 which can be evaluated without the introduction of this asssumption.
11. Theories of Diffusion I n the development of the theory of transport properties of mixtures, a significant step was taken by Bearman and I
