Development of mean isosteric heat activity coefficient model for the prediction of multicomponent liquid phase adsorption equilibria

Abstract

A purely predictive thermodynamically consistent adsorbed phase activity coefficient model has been proposed for the prediction of multicomponent liquid phase adsorption equilibria. The interaction parameters for this model have been estimated by a novel interaction correction parameter and mean isosteric heat (MIH) of adsorption which only requires pure vapor phase isotherms. The infinite isosteric heat values of Clausius-Clapeyron equation coupled with Dubinin-Astakhov isotherm were avoided by implementing extrapolations at saturated and zero loading limits. The resulting MIH activity coefficient model predicted the positive and negative deviations from ideality, and for adsorbates with close minimum dimension, the results were in excellent agreement with experimental data. Using adsorbed and bulk phase activity in a thermodynamic modeling procedure the excess amount adsorbed was estimated for polar and non-polar systems. The estimations of the proposed model were compared with the Ideal Adsorbed Phase (IAP) assumption and Hansen and Fackler's (H-F) approach. The results showed that excess amount adsorbed calculated with MIH model has an average mean absolute error value considerably less than IAP and H-F methods (0.0899, 0.268 and 0.533, respectively).