Prediction of adsorption from liquid mixtures in microporous media by the potential theory

Abstract

Despite its industrial importance, adsorption from the liquid phase has been studied much less extensively than adsorption from the gas phase. In this paper, we study the adsorption of liquid mixtures on the basis of the multicomponent potential theory of adsorption (MPTA). The MPTA is based on the potential concept originally developed by Polanyi. In this theory, the driving force for physical adsorption is measured by the adsorption potential that is a function of the distance from the solid surface. In this way, the adsorbate is considered as a heterogeneous substance segregated in the external field emitted by the adsorbent, with thermodynamic parameters that are function of the distance from the solid. The MPTA then uses a thermodynamic model to describe the equilibrium between bulk and adsorbed phases (or the fluid–fluid interactions), and potential models for the fluid–solid interactions. With this approach, few parameters are needed to predict adsorption equilibria. The MPTA has been so far used to successfully predict adsorption equilibria of multicomponent gas mixtures. The aim of this work is to extent the MPTA onto adsorption from liquid solutions. We show that such extension is straightforward, obtaining relatively simple models useful for engineering applications. Comparison with experimental data shows good agreement and high degree of predictability.