Development of\nthe Wilson Functional Activity Coefficient\nModel Using High-Quality and Critically Evaluated Phase Equilibria\nData

The activity coefficient is a key\nthermodynamic parameter,\nparticularly\nin phase equilibria calculations. Different activity coefficient models\nhave been developed to date, including empirical, correlative, predictive,\nand pure predictive. In this study, a predictive group contribution\nactivity coefficient model based on the Wilson model was developed,\nwhich is called the Wilson Functional Activity Coefficient (Wilson-FAC).\nHigh-quality and critically evaluated vapor–liquid phase equilibria\n(VLE) data was used in the optimization procedure to obtain the interaction\nparameters between the main groups. Different thermodynamic consistency\ntests, including the Herington test, Van Ness test, point test, infinite\ndilution test, EOS test, and end point test, were applied to check\nthe quality of the used VLE data. The interaction parameters between\nthe 50 main groups involved in the 137 molecules were optimized using\nthe <i>fminsearch</i> embedded function in MATLAB software.\nThe developed Wilson-FAC model covers solutions with various thermodynamic\nbehaviors, including ideal, moderately positive, and negative deviation\nfrom Raoult’s law and azeotropic systems as highly nonideal\nsolutions. Using the obtained interaction parameters from the binary\nVLE data, the model can accurately predict the phase equilibria of\nmulticomponent mixtures. The model covers the phase equilibrium behavior\nof all types of intermolecular interactions in binary systems well.