Analysis of cosolvent effect on supercritical carbon dioxide extraction for α-pinene and 1,8-cineole

The solubilities of α-pinene and 1,8-cineole in supercritical carbon dioxide with and without cosolvent were measured by using a circulation type apparatus coupled with an on-line Fourier transform infrared (FT-IR) spectroscope at 323 K and 8.0 MPa. The cosolvents interested in this work were ethanol, water, acetone and hexane. The solubilities were measured under vapor–liquid two phases. The effects of cosolvents on the solubilities and selectivities of α-pinene and 1,8-cineole in supercritical CO2 were investigated. The selectivities at feed concentration of cosolvent of 0.056 mol L−1 were increased 1.23 times by ethanol and decreased 0.82 times by hexane. Peng–Robinson equation of state with a quadratic mixing rule was used for correlations of the solubilities for α-pinene and 1,8-cineole in supercritical CO2 with and without cosolvent. The correlated results reproduce the experimental data of cosolvent effects on the solubilities and selectivities of α-pinene and 1,8-cineole in supercritical CO2.