Thermodynamics of Adsorption and Gibbsian Distance Parameters In Two-And Three-Phase Systems

Abstract

In a multicomponent, 2-phase system the Gibbs dividing surfaces for the respective components are separated by characteristic distances, A=rJ l)/AcJ. (I) More generally, if b designates an arbitrary criterion defining a surface, e.g. F; = Titand d designates another criterion, e.g. the surface of tension, Abd = 0Yb) - ivd))/Ac, = (r/b) - r nikc, (ii) For a binary, liquid-liquid system, (dr) • Ati _ m/T, sat dp In a 3-phase system with a line of 3-phase contact, it is possible to set up the one-dimensional analog of the Gibbs dividing surface, and to treat a linear excess mass that corresponds to the Gibbsian surface excess mass. The line of tension is the analog of the surface of tension. A linear thermodynamics can be developed, that is the one-dimensional analog of Gibbsian surface thermodynamics. Applications of eqns (I and III) are reported, for the estimation of A. For the interface between air and solutions of water and ethanol, at mole fraction ethanol = 0.18, A,2 is 8.8 A. For the benzene-water system, λi2 is found to be about 0.1 A. © 1976, Walter de Gruyter. All rights reserved.