A new way for calculating the adsorption capacity from surface excess isotherms

Abstract

 Adsorption of n-butanol and water from butanol–water mixtures is studied on adsorbents of different hydrophobicity (activated carbon and hydrophobized montmorillonites). The shape of the adsorption isotherms of the hydrophobized clay minerals does not indicate preferential adsorption of butanol. Therefore, the adsorption capacity cannot be determined on the basis of the Langmuir isotherm. A new equation for determining the adsorption capacity is derived by combining the free enthalpy of adsorption with the adsorption excess amount. Both collections of data are obtained from the surface excess isotherm. The reliability of the adsorption capacity is checked by X-ray diffraction measurements.