A NEW WAY FOR CALCULATING THE ADSORPTION CAPACITY FROM SURFACE EXCESSISOTHERMS

Adsorption of n-butanol and water from butanol-water mixtures is studi ed on adsorbents of different hydrophobicity (activated carbon and hyd rophobized montmorillonites). The shape of the adsorption isotherms of the hydrophobized clay minerals does not indicate preferential adsorp tion of butanol. Therefore, the adsorption capacity cannot be determin ed on the basis of the Langmuir isotherm. A new equation for determini ng the adsorption capacity is derived by combining the free enthalpy o f adsorption with the adsorption excess amount. Both collections of da ta are obtained from the surface excess isotherm. The reliability of t he adsorption capacity is checked by X-ray diffraction measurements.