Solubility of aspirin in supercritical carbon dioxide/alcohol mixtures

The introduction of polar cosolvents is not only able to dramatically increase solubilities of polar organic solids in supercritical CO2 but also can make supercritical CO2 extraction more attractive in various separation applications. In this study, we have measured the solubility of aspirin in methanol-modified and ethanol-modified supercritical CO2 by means of a dynamic saturation method. Experimental results show the aspirin solubility can be greatly enhanced up to 14 times by introducing 3.0 mol% methanol or ethanol. This enhancement, as believed, is mainly attributed to the strong attractive molecular interactions between the polar cosolvent and the polar solute. The aspirin ternary solubility data are fairly well described by using the Peng-Robinson equation of state model with an AARD ranging from 14 to 23%.