Viscosity measurement and modeling of lipid supercritical carbon dioxide mixtures

The viscosities of supercritical carbon dioxide (SC-CO2) containing different levels of methyl oleate and oleic acid were measured with a high pressure capillary viscometer. The SC-CO2-methyl oleate system was evaluated at 313.15, 323.15 and 333.15 K and 11.5, 13.7 and 15.5 MPa, respectively. The SC-CO2-oleic acid system was evaluated at 313.15 K and 20.5 and 30.0 MPa and 333.15 K and 30.0 MPa. The increase in SC-CO2 viscosity was as high as 15-20% at the maximum methyl oleate concentrations (4-5 wt%) and 6-12% at the maximum oleic acid concentrations (2-3 wt%). The increase of relative viscosity with concentration was linear. The lipid-SC-CO2 mixtures were Newtonian. The Arrhenius equation, modified by the excess Gibbs free energy using solubility parameters of the components based on the regular solution theory, predicted the liquid phase and the fluid phase viscosities of the lipid-SC-CO2 mixtures within +/-25% and +/-1%, respectively. (C) 1998 Elsevier Science B.V

Steady-state parallel plate apparatus for measurement of diffusion coefficient in supercritical carbon dioxide

A new, steady-state experimental system for measurement of the Fickian diffusion coefficients for solutes in supercritical carbon dioxide (SC-CO2) was designed and evaluated. Mass transfer between a Liquid solute and SC-CO2 was carried out in a parallel plate geometry where a porous metal sheet, immersed in the liquid phase, stabilized the interface. The SC-CO2 flowed over the porous metal sheet containing the liquid phase which was presaturated with CO2. The use of the porous metal sheet and a thin mobile layer allowed now rates high enough to achieve the necessary pressure drop to eliminate the commonly encountered, density-induced stagnation of SC-CO2 at the interface while avoiding surface-tension-related problems. The binary diffusion coefficients of methyl oleate in SC-CO2 at finite concentrations were measured at 40, 50, and 60 degrees C and at pressures ranging from 10.6 to 14.0 MPa. The experimentally measured values were 1.5-4.6 times lower than those predicted for infinite dilution and were found to decrease with solute concentration at constant pressure and temperature. This technique offers advantages over other commonly used methods in that the concentration dependence of diffusion coefficients in multicomponent systems can be studied

Continuous supercritical carbon dioxide processing of palm oil

Crude palm oil was processed by continuous supercritical carbon dioxide. The process reduces the contents of free fatty acids, monoglycerides and diglycerides, certain triglycerides, and some carotenes. The refined palm oil from the process has less than 0.1% free fatty acids, higher carotene content, and low diglycerides. Solubility of palm oil in supercritical carbon dioxide increased with pressure. A co-solvent improves the refining process of palm oil