Solubility of hydroxybenzoic acid isomers in ethyl acetate expanded with CO2

The solubility of p-hydroxybenzoic acid (p-HBA) and o-hydroxybenzoic acid (o-HBA) in ethyl acetate expanded with CO2 were determined at 308.15 and 318.15 K in the pressure range from 2.0 to 8.5 MPa. Both the solubility of p-HBA and o-HBA in the liquid phase decrease with pressure, especially at the higher pressures. However, the solubility of o-HBA in the CO2+ethyl acetate mixture is much higher than that of p-HBA under the conditions reported in this study. The CO2 mol fraction in the liquid phase was also investigated, which increased with pressure and decreased with temperature. Peng–Robinson equation of state was used to correlate the CO2 mol fraction and solubility of the two solutes in the liquid phase.