What is CO2 extraction process?
Supercritical carbon dioxide extraction has the advantages of high selectivity to solutes and low operating temperature, which can avoid thermal damage and no solvent residues.
In addition, carbon dioxide has the advantages of safety, non-toxicity, non-reactivity and easy complete separation from solutes, so it is quite popular among scholars and Industry attention.
Reduce cholesterol of CO2 fractionation
Since the 1980s, many researchers have applied the supercritical carbon dioxide extraction process to reduce cholesterol in foods.
Among them, the extraction of cholesterol in fats is the most researched, and butter is the most commonly studied in fats. It was used to extract cholesterol and oil from egg yolk and egg powder.
In addition, it is also used for the extraction of cholesterol in fish oil, squid oil, butter, lard, fish meat, beef, etc.
Traditional distillation technology
Generally, traditional distillation technology uses the difference in relative volatility between substances to achieve the purpose of separation.
When the relative volatility is less than 1.1, it is not economical to use traditional distillation technology to separate.
For systems with azeotropes, they cannot even be separated. At this time, special distillation techniques, such as azeotropic distillation, extractive distillation, salt-added distillation, pressure-sensitive distillation, and reactive distillation, are needed to achieve the purpose of purification.
Supercritical CO2 fractionation
Principle of sff
The liquid feed of supercritical fluid fractionation enters from the upper or middle section of the fractionation tower, and after reverse contact with the supercritical carbon dioxide entering from the bottom of the tower, the difference in the solubility of the separated matter in carbon dioxide is used to make the separated distillate and residue The materials flow out from the top and bottom of the tower.
Because the reflux of the supercritical fluid fractionation packing section increases the temperature along the packing column at a certain pressure, reduces the solvent capacity, and makes the fraction with less solubility separate from the supercritical fluid phase, so the temperature difference in the fractionation section directly affects The size of the reflux and the larger temperature difference are beneficial to improve the separation efficiency.
- In addition, for the distillation and purification of alcohols, the use of supercritical carbon dioxide can destroy the azeotropic situation.
- After solving the traditional distillation, the azeotrope still needs to be purified by molecular sieves.
- Traditional distillation is operated at high temperature, which easily causes the destruction of active substances in biotech products.
- Fractionation through supercritical carbon dioxide is low in operation temperature and can be recovered as long as the pressure is reduced, which not only avoids the destruction of effective ingredients, but also Reach the goal of energy saving and carbon reduction.
- In addition to the component separation of the activity of the crude extract obtained from the extraction to achieve the purpose of “concentration and purification”, if the separation is azeotropic, it cannot be separated by traditional distillation, such as the separation of water and IPA, which can also be easily achieved with this technology.
- In the near supercritical region, temperature is very sensitive to the influence of supercritical carbon dioxide fluid, so the correct selection of the temperature of the fractionation section is extremely important for the quality of the separation result.
- The temperature of the fractionation section can be determined by experiment to ensure normal operation. Generally, when the temperature is 10-40°C higher than the critical temperature, the normal operation of the system can be ensured and a good separation effect can be obtained.
Effact of temperature difference
Because the reflux of the supercritical fluid fractionation packing section increases the temperature along the packing column at a certain pressure, reduces the solvent capacity, and makes the fraction with less solubility separate from the supercritical fluid phase.
So the temperature difference in the fractionation section directly affects The size of the reflux and the larger temperature difference are beneficial to improve the separation efficiency.