INFLUENCE OF ADSORBATE SIZE AND ADSORBENT HETEROGENEITY ON IAST

The ideal adsorbed solution theory (IAST) can introduce serious errors in the calculation of multicomponent gas adsorption equilibria from t he corresponding pure gas adsorption isotherms when the adsorbate size s and the degree of adsorbent heterogeneity for adsorption of the comp onents differ substantially. The multisite Langmuir and heterogeneous Langmuir models were used to evaluate the extent of these errors. It i s shown that large differences in adsorbate sizes and degrees of heter ogeneity of adsorption of the components of a mixture can cause the fo rmation of an adsorption azeotrope that cannot be described by IAST.