Statistical thermodynamics of solid solubilities in supercritical fluids—A one-fluid conformal theory approach

Abstract

Supercritical fluid extraction involves highly asymmetric mixtures at conditions close to the critical point. The thermodynamic modelling of these mixtures is therefore inconveniently described by the conventional methods, namely the analytical equations-of-state with conventional mixing rules (which are poorest in the near supercritical region). Based on the one-fluid conformal solution theory, we present here a procedure to correlate (and ultimately to predict) the thermodynamic behavior in supercritical fluid extraction processes. The method described in this work allows the correlation (as well as interpolation and extrapolation) of solid solubilities in supercritical solvents at different pressures and temperatures.