Description of polymolecular adsorption on energetically heterogeneous surfaces

Abstract

The Dubinin-Radushkevich equation is used for description of the first and subsequent adsorp tion layers in the case of polymolecular adsorption on energetically heterogeneous surfaces. It is found pos sible to predict adsorption isotherms of various vapors on nonporous and macroporous adsorbents on the basis of the minimal scope of experimental data. The derived two parameter equation of multilayer adsorp tion describes the adsorption equilibria in almost the whole range of mono and polymolecular adsorption, which is not complicated by capillary condensation, specific adsorption, or adsorption in micropores. When there are micropores and specific interactions between the adsorbate and the surface, the equation in the polymolecular range (beyond point B) enables one to characterize the surface and porosity of the adsorbent with respect to diverse adsorbates without information about standard adsorption isotherms, which makes the applicability field of the adsorption methods much broader and more valuable.