As the most widely used fluid in today's extraction technology, supercritical CO2 extraction has the following remarkable advantages:

1) operating close to room temperature (34 to 39 ℃), the extraction process, under the shadows of the CO2 gas effectively prevent the oxidation and degradation of thermal sensitive material. It can retain biological activity completely and extract materials with high boiling point, low volatility and pyrolysis at a temperature far below its boiling point.

2) it is the greenest extraction method. The whole process does not contain organic solvent, so the extract has no solvent residue, thus preventing the existence of harmful substances in human body and environmental pollution during the extraction process and ensuring 100% natural.

3) extraction and separation are combined. When the dissolved CO2 fluid enters the separator, the pressure or temperature is adjusted so that the CO2 and the extract rapidly become two phases (gas-liquid separation) and immediately separate. The extraction efficiency is high and energy consumption is low, which improves the production efficiency and reduces the cost.

4) CO2 is an inert gas, which does not undergo chemical reaction during extraction and is a non-combustible gas. It is tasteless, odorless, non-toxic and safe.

5) strong extraction capability and high extraction rate; Quick extraction time and short production cycle.

6) pressure and temperature can be used as parameters to adjust the extraction process. The purpose of extraction can be achieved only by changing the extraction temperature and pressure. The purpose of separation can be achieved by changing the separation pressure or temperature.

7) supercritical CO2 also has antioxidant and sterilization effects, which is conducive to guarantee and improve product quality;

Of course, supercritical CO2 extraction is not a panacea extraction technology, as any other technology, but also applicable scope. We need to determine whether it is suitable for use according to its solubility to different substances. In general, the solubility of supercritical CO2 to different substances has the following rules:

A) lipophilic and low-boiling components can be extracted below 10MPa, such as aromatic components in natural plants and fruits.

B) when the relative volatility or polarity of the components in the mixture is significantly different, the mixture can be fractionated at different pressures.

C) the introduction of strong polar groups (-oh, -cooh) makes extraction difficult. In the range of benzene derivatives, compounds with three hydroxyl phenols, and with a carboxyl and two hydroxyl groups can still be extracted, but those with a carbonyl and more than three hydroxyl groups cannot be extracted.

D) more polar substances, such as sugars, are difficult to extract below 40MPa.

E) the higher the molecular weight of the compound, the harder it is to be extracted. Articles come from the Internet

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