Supercritical CO2 extraction temperature
Factors Affecting Supercritical CO2 Extraction of Vegetable Oils
The extraction temperature is another very important parameter that affects the density of supercritical CO2. Compared with the extraction pressure, the effect of extraction temperature on the supercritical CO2 fluid extraction process is much more complicated.
Under a certain extraction pressure, there are two trends in the effect of extraction temperature on the extraction of vegetable oils:
Higher extraction pressure
As the temperature increases, the oil yield gradually increases, and when it exceeds a certain temperature, it gradually decreases. This situation occurs when the extraction pressure is high.
This is because when the extraction pressure is high, the CO2 density is high, the compressibility is small, and the CO2 density decreases less when the temperature is raised, but the vapor pressure of the components to be separated and the diffusion coefficient of the material are greatly increased, and the dissolution capacity is improved.
Lower extraction pressure
As the temperature increases, the product yield shows a decreasing trend, which occurs at lower extraction pressures.
This is because near the critical point of supercritical CO2, when the pressure is low, the compressibility of supercritical CO2 is large, and the density of CO2 drops sharply when the temperature is raised. At this time, although the volatility and diffusion coefficient of the separated components can be increased, it is difficult to compensate The decrease in solubility caused by the decrease in CO2 density.
How to choose the extraction temperature
In addition, as the temperature increases, while the extraction rate increases, the solubility of impurities will also increase accordingly, thereby increasing the difficulty of the separation and purification process, which may reduce the yield of the product, and high temperature may cause certain components The denaturation, decomposition or failure of the extract, so these factors should be considered comprehensively when selecting the extraction temperature.
Recommended supercritical CO2 extraction temperature for vegetable oils
Since most vegetable fats and oils contain unsaturated fatty acids, the extraction temperature should be relatively mild, generally between 30 and 50 ℃.