Effects of Cosolvents on the Solubility of β-Carotene in Supercritical Carbon Dioxide

The solubilities of β-carotene in pure supercritical carbon dioxide with, respectively, the cosolvents of ethanol, acetone, and n-hexane were measured using a semi-flow type apparatus and ranged from 15 MPa to 28 MPa under a temperature range of 313.15 K to 333.15 K. With regard to the experimental solubilities in pure supercritical carbon dioxide, the data are consistent with values reported in the literature with a magnitude order from 10^(-8) to 10^(-7) in mole fraction. The experimental results showed that the cosolvents increased the solubility, and the effect in the order of acetone ＞n-hexane ＞ethanol with exceptions under some experimental conditions as described in the paper. The largest enhancement in the solubility by a cosolvent appears at 333.15 K, 15 MPa with 10% n-hexane in the solvent mixture. The experimental solubility data of β-carotene in CO2 were correlated fairly well with the Peng-Robinson equation of state incorporated with the modified van der Waals mixing rule, and with the method of Debenedetti and Kumar. The experimental data of β-carotene+CO2+ethanol, β-carotene+CO2+acetone, and β-carotene+CO2+n-hexane systems were correlated with the modified empirical equation of Chrastil.