Equilibrium solubilities of β-carotene in supercritical carbon dioxide

Abstract

Equilibrium solubilities of pure crystalline β-carotene in supercritical CO 2 have been measured using an LDC Analytical SPA extractor 1 1 Reference to a brand or firm name does not constitute endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned. . The apparatus features a recirculating loop with an in-line UV detector. Quantitation by UV absorbance permits the detection of lower solubilities than can normally be obtained gravimetrically. The values reported were obtained at temperatures from 40 to 70°C and pressures from 200 to 500 bar. The measured mole fractions ranged from 9.0×10 −9 at 40°C and 275 bar to 1.9x10 −6 at 70°C and 400 bar. Solubilities are also reported for β-carotene in mixtures of CO 2and 1 wt.% ethanol, 1 wt.% methanol and 1 wt.% methylene chloride, at 70°C and various pressures. Addition of the cosolvent increased the solubility in every case, with the largest increase occurring in a mixture of CO 2 and 1 wt.% ethanol. Pure component properties for β-carotene were estimated, and the experimental data were correlated to a modified Peng-Robinson equation of state. The model predictions compare well with the experimental data.