Kinetics of cholesterol extraction using supercritical carbon dioxide with cosolvents

Cattle brain is rich in lipids including cholesterol. As a alternative process to extract cholesterol, the ecofriendly solvent supercritical carbon dioxide (SC CO₂), along with different cosolvents such as acetone, 2-propanol, and ethanol, was used in an attempt to understand the effect of cosolvents. A maximum of 53% of the total cholesterol in the brain sample could only be extracted either using pure SC CO₂ or using cosolvents along with SC CO₂. Although the total amount of cholesterol extracted did not differ with the addition of cosolvents, the rate of extraction was found to increase significantly with the addition of cosolvents in small quantities. The kinetics of extraction using pure SC CO₂ as well SC CO₂ with cosolvents was modeled using conventional differential mass balance equation for packed beds. The effective diffusivity coefficient was found to double with cosolvent acetone, while found to be more than three times with cosolvents 2-propanol and ethanol in comparison with the pure SC CO₂. The effective diffusivity coefficient was found to be of the order of 10 ^-13 m²/s, for extraction of cholesterol from cattle brain, either with SC CO₂ or SC CO₂ with cosolvents.