3 key points of supercritical CO2 extraction.
What are the 3 key points of supercritical CO2 extraction?
HOW TO CHOOSE THE RIGHT CO2 EXTRACTOR?
CO2 Extraction Machine Buyer’s Guide
As you can imagine, not all supercritical CO2 extractors are made the same.
For more than 30 years, we have customized many CO2 extraction machines (Tabletop CO2 Extractor) for many companies and university laboratories (1 lb CO2 extractor). Because each customer’s CO2 extraction process requirements are different, there are almost no identical machines.
How many liters of CO2 extraction vessel are needed？
The first factor that determines the size of the CO2 extraction vessel is the daily working hours of the plant, which determines the daily extraction batch. The vessel size of the CO2 extractor depends on the biomass to be processed per day.
How many separators are needed?
How can I custom my separator when I need more terpenes in my How can I custom my separators when need more terpenes in CBD oil extraction process? Waxes separation and Light oil separation in 1st separator; Light oil separation in 2nd separator; To trap lightest and volatile compounds in 3rd separator. It is important to choose the right vessel size that will meet your current needs as well as future demand.
How many pressure is best for your CO2 extraction process requirements?
The choice of CO2 extraction pressure is a changing factor. If the extraction pressure is too high, the useless substances in the plant will be extracted, such as wax and chlorophyll. If the extraction pressure is too low, the extraction time will be increased.
How can the minimum operating costs be achieved?
Further Reading: CBD Oil CO2 Extraction Machine
What are the optimal CO2 extraction process parameters?
CO2 extraction process operating parameters mainly include extraction pressure and temperature, extraction time, ratio of solvent to material flow rate or solvent flow rate, etc.;
The density and dielectric constant of supercritical fluids are large, and the solubility of substances is also large, and they change rapidly with the changes of temperature and pressure. Therefore, the ability to dissolve certain substances is strong and selective, and the solvent and extract are easily separated at room temperature.
What is the best extraction pressure for CO2 extraction process?
The dissolution capacity of supercritical CO2 fluid is proportional to the density. Near the critical point, if the pressure changes slightly, its density will have a relatively large change.
Therefore, for many solid or liquid solutes, if the solute and the solvent are not mutually soluble indefinitely, the dissolving ability of the supercritical fluid and the pressure have a significant correlation.
Under different pressures, the range of extracts is different. When extracting low molecular weight essential oil components (aromatic components) under low pressure, as the pressure increases, the range of extractable substances expands, but the two are not linear. When the pressure increases to At a certain level, the dissolving power increases slowly.
At the same time, the pressure is limited by equipment investment, safety and production costs. Therefore, in actual production, the pressure should not be raised unrestrictedly just to increase the yield, and comprehensive indicators such as product resources and overall operating parameters should be considered.
Example of extraction pressure
For the extraction of seasonings and flavors, the parameters can be selected in a relatively wide range. For materials containing only high solubility substances, choosing a low pressure zone of 7.0 MPa to 12.0 MPa is conducive to selective separation.
Terpenoids can achieve high solubility in CO2 at 9.1MPa～12.2MPa, while neutral grease generally needs more than 16.2MPa.
- In the SC-CO2 extraction of cardamom oil, when the pressure is between 10MPa and 60MPa, the yield is relatively stable, but the content of non-volatile components increases with the increase of pressure, and at the same time, the loss of volatile components increases. ;
- When the temperature is the same, the solubility of pepper essential oil in the low-pressure zone increases rapidly with the increase of pressure, and when it reaches a certain value, it tends to balance;
- While the extraction rate of piperine increases with the increase of extraction pressure within the test range, and the high pressure ( ≥30MPa) SC-CO2 can effectively extract various pigments and capsicum in pepper.
- For some strongly polar substances containing -OH, -COOH and benzene hydroxyl groups, higher extraction pressures are also required.
The best supercritical CO2 extraction pressure for plant essential oils: 8.0MPa～12.0MPa.
But in our actual application, the best extraction pressure range is: 10 MPa-35 MPa.The extraction of astaxanthin is an exception, which requires a pressure above 70 MPa.
What is the best temperature for co2 extraction process?
Under constant pressure, the solubility of supercritical fluid may increase, but not decrease. The different isothermal solubility lines intersect at a point, which is called the change point.
Above and below the change point, the solubility will change differently with the change of temperature. This is because:
- As the temperature rises, the thermal motion of molecules accelerates, the probability of collision with each other increases, and the chance of association increases;
- The increase in temperature increases the volatility and diffusion coefficient of the solute;
- As the temperature increases, the CO2 density decreases and the ability to carry substances decreases.
Therefore, the extraction rate depends on which state prevails at this temperature.
- When the pressure is high, the CO2 density is very large, the compressibility is small, the increase in the molecular distance caused by the heating and the weakening of the intermolecular force, and the acceleration of the molecular thermal motion and the increase in the probability of collision have little effect on the solubility.
- When it is low, the increase in vapor pressure of the solute caused by the temperature rise is insufficient to compensate for the decrease in the solubility of the CO2 fluid, so the overall effect leads to a decrease in the solute concentration in the supercritical fluid.
Optimal stress conditions
For a certain substance to be extracted, there is an optimal extraction temperature that balances the above two contradictions under the optimal pressure conditions.
When the temperature rises from 40℃ to 60℃, the main components, especially the volatile components, are significantly reduced due to the high temperature flash volatilization carried by CO2, and the high temperature extraction operation extract contains more water. The high temperature process may increase the volatility of water, but it is not conducive to the extraction of terpenes and oxygenated derivatives. If the extract is a heat-sensitive active ingredient, it is especially important to consider using a lower temperature for extraction.
In the study of extracting allicin, it was found that when the extraction temperature was 45℃, the chromatogram of the extract reflected many small peaks of decomposition products. The chromatograms of the extracts at 25°C and 36°C are similar to the solvent extraction method, and the chromatograms of the extracts did not reflect many small peaks of decomposition products.
Optimum CO2 extraction temperature: 35℃～50℃
Optimal extraction conditions
The research results so far show that the optimal extraction conditions are generally between 8.0MPa～12.0MPa and 35℃～50℃.
As we all know, under higher CO2 density (such as 40°C and pressure higher than 20.0MPa), SC-CO2 exhibits strong solubility and lower selectivity. In fact, the extraction rate increases under high-density CO2 Mainly due to the increase of surface wax and other undesirable ingredients.
Adjusting the solubility and selectivity of supercritical fluids is helpful to overcome technical difficulties such as one-time extraction and entrainment extraction of non-volatile components in separation.
Under the condition of CO2 density lower than 0.6g/cm3, it is possible to extract as much essential oil components as possible, and other non-volatile components except surface wax will not be extracted.
When the CO2 density is too high, such as higher than 0.85g/cm3, not only the extraction rate decreases, but also technical difficulties are caused by the increase in the extraction of waxes and triglycerides.
Separation operating parameters include separation pressure and temperature, phase separation requirements, and solvent recovery and treatment in the process. The supercritical fluid circulation time depends on the solute extraction capacity and separation coefficient of the supercritical fluid.
Separation pressure and separation temperature
After the extraction process, the density of the SCF must be reduced to selectively separate the extract in the separator. To implement this separation, there are generally three adjustment methods, constant pressure heating or constant temperature pressure reduction, or pressure reduction and heating. The optimized operating conditions must be obtained through specific experiments.
When the separation pressure is constant, as the temperature of the separation process increases, the ability of CO2 to carry substances decreases, and it is easy to separate the extracted substances, but the selective separation is poor, and it is not easy to obtain a purer single substance, and the final product is purified. The process is complicated and the loss is large, resulting in a low yield of the final product, and the higher the temperature, the more likely the volatile substances will be lost with CO2, which is also detrimental to the heat-sensitive components.
In order to obtain purer extracts, or products with more volatile components, and to protect heat-sensitive substances, it is necessary to control a more appropriate separation temperature.
As the working pressure of the separation decreases, the density of SC-CO2 changes, so that the extract that has been dissolved in it will be separated due to the decrease in pressure after entering the separation kettle, but as the working pressure decreases, the separation rate is Tend to balance.
The separation pressure is different, the chemical composition of the extract will also have a certain difference. For extracts with poor single-stage separation, two-stage or even multi-stage separation should be considered.
The SC-CO2 extraction and separation of fennel oil uses two-stage separation.Under different separation conditions, the yield of the two products depends on the pressure of the first separator, but the pressure adjustment of the first separator has a certain range. If it is too high, fats, lipids and pigments cannot be deposited in the first separator, which will cause the second separator to contain these three types of substances, thus losing the advantages of fractionation.
Therefore, reasonable adjustment of the process parameters of the separator is the key to achieve the purpose of separating different substances.
Read More ↗
Here we have compiled some articles about Supercritical Fluid (SCF) in the station, hope they can help you.
How to obtain the best operating parameters for supercritical CO2 extraction process
Laboratory feasibility studies usually use methods such as least squares method, single factor test or response surface method to study the influence of various factors on the extraction rate (or recovery rate) and selectivity of the target substance, so as to optimize the appropriate operating parameters.
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CO2 extraction process you can find
From raw material preparation, we offer you the most complete CO2 essential oil extraction process.
At the same time, more than 100 CO2 essential oil extraction methods from the laboratory are also provided for you.
Detailed explanation of CO2 extraction process steps of plant essential oils。
About the co2 extraction machine cannabis. You can read a lot of articles about cbd oil extraction from the Internet, but I can tell you for sure that they are not comprehensive at all, and even have wrong descriptions.