Modeling of Polar Systems Using PCP-SAFT:  An Approach to Account for Induced-Association Interactions

The perturbed-chain polar statistical associating fluid theory (PCP-SAFT) equation of state is applied to mixtures containing polar as well as associating components where cross association may occur. In this work, we focus on mixtures in which at least one of the components does not self-associate but is able to form hydrogen bonds with other compounds, for example, water and alcohols. On the basis of the mixing rules from Wolbach and Sandler 1 for associating components, we propose a simple approach to account for this type of cross association (referred to as induced association) only from the knowledge of pure-component parameters. The application to vapor−liquid and liquid−liquid equilibria of numerous binary and ternary mixtures of polar components with alcohols and/or water revealed the strength of the proposed approach. It is confirmed that accounting for induced-association interactions improves the predictive capability as well as the ability of the model to correlate mixture phase equilibria quantitatively. It is worth mentioning that only temperature-independent parameters are used for all calculations, and no additional adjustable parameters are introduced.