Adsorption of a simple fluid in a quenched two-component hard sphere matrix replica Ornstein-Zernike equations

Abstract

Using the replica Ornstein-Zernike (ROZ) integral equations, we investigate the adsorption of a simple fluid in a hard sphere quenched matrix made of two species. Our main focus is in the dependencies of the density of fluid species on the chemical potential in matrices with different microporosity and for several compositions. The simple fluid is considered by using a hard sphere model. The fluid-matrix interactions are assumed either solely repulsive or attractive of the Yukawa type. The ROZ equations are supplemented by both the Percus-Yevick (PY) and the hypernetted chain (HNC) closures. The PY closure is used to study the model with solely repulsive forces (reference system) and then the contribution of attractive forces into adsorption is included in the mean field approximation. On the other hand, the HNC approximation is used to get insight into the structure of adsorbed fluid and the fluid-matrix correlations in the presence of attractive forces.