Mathematical model for multicomponent adsorption equilibria using only pure component data

A mathematical model for nonideal adsorption equilibria in multicomponent mixtures is derived and applied with good results for pure components as well as multicomponent mixtures using only pure component data. The multicomponent model is derived on the basis of vacancy solution theory and Non-Random-Two-Liquid (NRTL) theory. The NRTL equation is able to describe immiscible liquid systems which indicates that the mathematical model may be capable of describing strongly nonideal adsorption systems. The combination of the vacancy solution and NRTL theories accounts for adsorbent-adsorbate and adsorbate-adsorbate interactions by means of surface phase activity coefficients which depend on temperature, composition and spreading pressure. Fugacity coefficients in the bulk gas phase are calculated by the Second Virial Equation.