Vacancy solution model using the aNRTL activity coefficient for prediction of binary adsorption equilibria

Abstract

Based on the Vacancy Solution Model (VSM) and the Adsorption Non-Random Two-Liquid (aNRTL) model of the activity coefficient, a novel model called VSM-aNRTL for gas adsorption equilibria is introduced. In this study, an innovative isotherm equation was applied to experimental monocomponent adsorption equilibrium data from the NIST/ARPA-E Database. The parameters derived from this application were subsequently utilized to predict the equilibrium data for 12 binary adsorption systems across three distinct temperatures, employing the extended model. The proposed model proved effective in correlating the adsorption isotherms of pure components, achieving a reduction in the number of adjustable parameters compared to the original VSM that employs the Wilson activity coefficient. It also outperformed the Ideal Adsorbed Solution Theory (IAST) model by incorporating only one additional parameter. Furthermore, the new model was employed to predict the equilibrium data of binary mixture adsorption, demonstrating results with lower deviations compared to both the IAST and the traditional VSM-Wilson models.