Calculations of solid solubility in supercritical fluids using a simplified cluster solvation model

A simplified cluster solvation model was employed in this study to correlate the solid solubility in supercritical fluids. Based on the concept of cluster solvation, several supercritical molecules were associated with a solid solute in chemical equilibrium. Solid solubility was calculated by applying the equilibrium criteria for the cluster formation process. This simplified model has two temperature-independent binary parameters. It is observed that the overall deviation in solid solubility calculations of binary systems from this model is comparable to that from other semi-empirical models with more optimally fitted parameters. This simplified cluster solvation model was extended to ternary and multi-component calculations by directly using the parameters from binary correlation results. Without any additional parameter, the predicted accuracy is still acceptable. Application of this model to systems with co-solvent has also been examined. A general trend for the variation of the effective association number with co-solvent concentration is observed.