Supercritical CO2 extraction in natural products
Supercritical fluid extraction (SFE) has shown great advantages in solving many complex separation problems, especially in extracting valuable bioactive substances from natural plants and animals.When extracting some components of natural products, the extraction efficiency of CO2 will be greatly reduced due to its strong polarity, large molecular weight, and being bound by relevant substances. At this time, it can be considered to add appropriate entrainers to enhance its solubility and selectivity, so that substances with strong polarity and large molecular weight can be extracted.
1.Working Principle
According to the need of experiment, supercritical CO₂ and entrainers can enter the extraction kettle at the same time. The ratio of the two is controlled by the frequency modulator and the metering pump. The Co2 gas from the cylinder is cooled and liquefied into the refrigerator through the filter, and then pumped into the pipeline through the metering pump, while the eentrainers is pumped into the pipeline by the entrainers pump, and the two are mixed in the mixer and enter the extraction kettle (heat preservation in the constant temperature water bath). After the set conditions are reached, the cyclic dynamic extraction and separation begins. The CO2 gas containing the solute enters the separator after the pressure reduction, and the solute separates the CO2 for recycling.
2.Option
Polar entrainers water, ethanol, methanol, acetone, acetic acid, ethyl acetate,etc
Non-polar entrainers petroleum ether, cyclohexane, n-hexane, etc
3.Method of application
- Mixing with carbon dioxide: Before the carbon dioxide enters the extraction kettle, the entrainers is mixed with the carbon dioxide through the entrainment pump and then enters the extraction kettle together. This method can make the entrained agent evenly distributed in supercritical carbon dioxide and improve its contact efficiency with the target component.
- Pre-mix with material: In some cases, the entrainers can be pre-mixed with the material to be extracted and then placed together in the extraction kettle. This method is helpful to improve the utilization rate and extraction efficiency of entrainers.
4.Application
It is widely used in the extraction of alkaloids, phenolic acids, saponins, flavonoids, fatty acids and other natural products. In general, increasing the amount of entrainers can increase the yield, but when the amount of entrainers reaches a certain degree, the effect of increasing the yield will not be too obvious, so it is necessary to choose a suitable amount.
