Binary liquid flow in micropores

Abstract

Experimental values of phenomenological coefficients for liquid flow through porous (Vycor) glass are presented at two or more compositions for each of the binary systems: I, C₆H₆(1)+CCl₄;II, C₆H₆(1)+C₆H₁₂; III, CCl₄(1)+C₆H₁₂. Hydrodynamic flow and ordinary diffusion in pores of about 26 Å radius are described approximately by the usual macroscopic equations; discrepancies may be interpreted by means of a micropore model in terms of frictional and adsorption effects in a slipping monolayer film at the pore surface. The increase which occurs in the Staverman reflection coefficient ¹²σ with decreasing volume fraction of the selectively adsorbed component (1), especially in system II, are explained in terms of a net volume flow due to an interfacial tension gradient which arises when selective adsorption occurs in the presence of a concentration gradient. A contribution to σ also results from a difference in friction coefficients per unit volume for the two solution components in the surface film. An apparent experimental discrepancy (system I) between the cross-coefficients for volume and relative velocity flow is not explained by the theory.