SOLUBILITIES OF SELECTED COMPOUNDS OF CITRUS PEEL OIL (FARNESOL AND NARINGENIN) IN SUPERCRITICAL CO_2

摘要

We measured the solubility (y2, molar fraction) in supercritical carbon dioxide (CO_2) of two bioactive compounds in citrus peel oil, namely farnesol (an oxygenated sesquiterpene) and naringenin (a flavonone) using an static-analytic method (a high-pressure static equilibrium cell coupled to an HPLC). The molar fraction of farnesol in the saturated CO_2 phase ranged from Y_2 = 0.13×10~(-3) at 333 K and 11.4 MPa to y_2 = 1.91×10~(-3) at 333 K and 26.0 MPa, and a cross-over point was identified at approximately 17 MPa. The molar fraction of naringenin in the CO_2-rich phase, on the other hand, increased with both system temperature and pressure from y_2 = 0.49×10~(-5) at 313 K and 10.3 MPa to y_2 = 1.65×10~(-5) at 333 K and 44.5 MPa, and the differences in solubility between the two solutes can be related to differences in their molecular weights and polarities. Experimental data points were correlated using the model of Mendez-Santiago and Teja for solute solubility as a function of CO_2 density, which was also used to assess the auto-consistency of the experimental data.