Solubility Model of Solid Solute in Supercritical Fluid Solvent Based on UNIFAC

A semitheoretical model based on UNIFAC was proposed to correlate the solubility of solid solute in supercritical fluid (SF) solvent simply and reliably, which does not need critical parameters for solid solutes. The interaction parameters a ij between the SF solvents (such as carbon dioxide, ethylene, and ethane) and the functional groups of solutes were regressed, which is compatible with the vapor−liquid equilibrium (VLE) UNIFAC group-interaction parameters. More efforts and experimental data are needed to obtain a sufficiently large number of interaction parameters for extensive applications. The estimated power exponent of reduced density seems identical for the same solid solute in SF cosolvent homologues. This model could predict the solubility of a solid solute in supercritical CO2 with cosolvents successfully.