REPLICA ORNSTEIN-ZERNIKE EQUATIONS AND THE STRUCTURE OF A SIMPLE FLUID MIXTURE IN DISORDERED POROUS-MEDIA - APPLICATION TO A COMPOSITE MONOMOLECULAR ADLAYER

A two-dimensional (2D) model for a simple fluid mixture, consisting of spherical particles with different diameters that is adsorbed on a di sordered porous medium, i.e., in a plane claiming hard discs in a froz en configuration, is studied by means of replica Ornstein-Zernike equa tions. The hypernetted chain and Percus-Yevick approximations are used . The structural and thermodynamic properties of the composite monomol ecular adlayer are addressed, and the density and composition of the m onolayer and their dependence on the presence of a disordered quenched 2D matrix in the plane of absorption at a fixed chemical potential is examined. Tt is shown that porous 2D media exhibit the effect of sele ctivity. The concentration of the smaller particles is larger on the p orous media compared with the bulk phase. The model and methodology ca n be extended to study phase transitions in 2D partly quenched systems .