Adsorption from binary liquid mixtures of unequal adsorbate sizes on heterogeneous asorbents

Abstract

A new analytic surface excess isotherm is derived for adsorption of a binary liquid mixture of dissimilar adsorbate sizes on a heterogeneous adsorbent. The model assumes that (a) the monolayer adsorption model with an ideal adsorbed phase describes the local adsorption on the homogeneous sites of the adsorbent and (b) the adsorbent heterogeneity can be described by a uniform distribution of the site adsorbate selectivity. The theory is tested using data for adsorption of benzene + cyclohexane mixtures on silica gel. A parametric study of the effects of the adsorbate sizes and the degree of surface heterogeneity on the shapes of the surface excess isotherm is carried out to demonstrate the complexity of interactions between these variables.