A Real Adsorbed Solution Theory model for competitive multicomponent liquid adsorption onto granular activated carbon

In this work, a new Real Adsorbed Solution Theory (RAST) model, for competitive multicomponent adsorption equilibrium correlation in liquid systems has been developed. The model is derived from Ideal Adsorbed Solution Theory; in its formulation it explicitly takes into account the non-ideal behavior shown by most of the adsorption systems. The occurrence of interactions among adsorbed molecules is accounted for by the introduction of activity coefficients, as a function of sorbates adsorption capacity and spreading pressure. These coefficients are experimentally evaluated through multicomponent adsorption isotherms determination, also considering single-compound adsorption isotherm parameters in the model formulation. The RAST model was tested on the experimental results of tetrachloroethylene/trichloroethylene (PCE/TCE) binary mixtures adsorption, obtained at constant temperature and different concentration ratio of the two compounds. This model, with the experimental determination of activity coefficients, allowed an accurate description of PCE/TCE binary adsorption experimental data, thus being a reliable instrument for the design of industrial adsorption equipment for wastewater containing a mixture of pollutants.