A New Development in the Application of the Group Contribution Associating Equation of State To Model Solid Solubilities of Phenolic Compounds in SC-CO2

The potential of the Group Contribution Associating Equation of State (GCA-EoS) to correlate and predict the solubilities of solid phenolic compounds, e.g. phenols, aromatic ethers, and aromatic acids, in supercritical carbon dioxide is explored in this work. The Carnahan-Starling type repulsive term of the GCA-EoS equation contains a molecular parameter, the hard sphere diameter di, which is assumed to be temperature-dependent in the original model and is calculated following a generalized expression. In the present study, this expression is singled out as a target for improvement, since it was established that the low-volatile solid compound diameter value influences to a great extent the phase equilibrium calculations. The paper demonstrates that a density-dependent solute di parameter can better represent the experimental solubility data of the compounds studied and maintains the group contribution character of the model.