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What is the most commonly used supercritical fluid for extraction

活動日期:2021-11-01

What is th

活動說明

What is the most commonly used supercritical fluid for extraction? The most commonly used supercritical fluid is supercritical carbon dioxide because it has a moderate critical temperature (31.26°C) and pressure (72.9 atmospheres).

Why is carbon dioxide used as a Supercritical CO2 Extraction machine?
When the temperature is higher than the critical temperature Tc=31.26°C and the pressure is higher than the critical pressure Pc=72.9 atm, the properties of carbon dioxide change. Its density is close to that of a liquid, its viscosity is close to that of a gas, and its diffusion coefficient is 100 times that of a liquid. It has an amazing solubility.

In addition, since carbon dioxide is a gas at room temperature, it can be easily separated/removed to produce solvent-free extracts.

Supercritical carbon dioxide has a wide range of applications as it can dissolve a variety of substances and thus extract the active ingredients.

Supercritical CO2 is one of the most widely studied fluids because it has the following properties.

CO2 has a critical temperature of 31.26°C and a critical pressure of 72.9 atm, which easily achieves critical conditions.
CO2 is chemically inert, colorless, odorless, non-toxic and safe.
It is cheap, pure and easy to obtain.
Is Supercritical CO2 Extraction (SFCE) safe?
CO2 is the safest as far as non-polar solvents are concerned. In fact, the FDA has labeled CO2 as safe for industrial extraction, making it a less controversial solvent than petroleum-based hydrocarbons such as butane or propane.

Is supercritical CO2 extraction better?
Supercritical CO2 extraction is also much better for the environment. CO2 gas is natural, so if it escapes into the air during the extraction process, it will not cause any harm. It can also be recycled, making this method more sustainable. Since the solvent is non-toxic, there are no health risks for those using this extraction method.

Is supercritical CO2 corrosive?
Dry supercritical CO2 fluids are non-corrosive.

Supercritical water fluids are very corrosive.

What is supercritical water?
Water has a critical temperature of T=374°C and a critical pressure of P=22.1 MPa.

When the temperature and pressure of a system exceed the critical point, it is called supercritical water.

What does supercritical water look like?
There is no difference between the liquid and gaseous states of water in the supercritical state; they are completely fused together and become a new fluid that presents a high pressure and high temperature state.

The "supercritical" state can be thought of as the "fourth state" of a material. It is not a solid, liquid or gas - it is a form of steam.

What are the characteristics of supercritical water?
It has a very high oxidation capacity. The material to be treated is placed in supercritical water and oxygen is dissolved in it (in large quantities). Its oxidizing power is stronger than that of potassium permanganate.

Many substances can burn in it and emit flame.
It can dissolve many substances (e.g. oil) and the volume will be greatly reduced when dissolved because the supercritical water will then tightly encapsulate the oil.
It can slowly dissolve and corrode almost all metals, even gold (similar to aqua regia).
Super catalytic, in supercritical water, chemicals react very fast, some up to 100 times more horrible!
What can supercritical CO2 extract?
Supercritical fluid extraction with CO2 as a single medium is mainly used for lipophilic, non-polar substances with small molecular weight, i.e.

Supercritical fluid extraction with CO2 as a single medium is mainly used for lipophilic, non-polar substances with small molecular weights.
The compounds mentioned in the solubility rule ② and solubility rule ③ are miscible with supercritical CO2 or have high solubility.

If the ingredients in the raw material belong to the compounds mentioned in solubility rule ⑤ and solubility rule ⑥, they are difficult to extract and remain in the extract solution.

What can supercritical CO2 dissolve?
Studies have shown that extracts of supercritical pure CO2 are mostly mixtures of volatile oils, fats, alcohols, ethers, esters, resins and other lipophilic chemical components.

What are the advantages and disadvantages of supercritical fluid extraction?
What are the advantages of supercritical CO2 (SFE)?
What are the benefits of using supercritical fluids?

Supercritical CO2 is heavily used for extraction because it has the following characteristics of extraction technology.

Natural and environmentally friendly with no soluble residues
Supercritical CO2 fluid is a colorless, odorless and non-toxic gas under normal conditions. After the separation of the extracted components, there is no solvent residue at all, which can effectively avoid the toxic residue of solvent under the traditional solvent extraction conditions.

It also prevents the extraction process from being toxic to human body and polluting to the environment. It is a natural and environmentally friendly extraction technology.

Near room temperature extraction
Since supercritical CO2 extraction can achieve supercritical extraction near room temperature, it avoids the decomposition of heat-sensitive substances caused by high temperature operation, easy solute separation and no solvent residue problems, which is conducive to ensuring and improving the quality of natural products, therefore, supercritical CO2 extraction is regarded as a green chemical technology.

Why is carbon dioxide extraction better than steam distillation?
In steam distillation, the molecular composition of plant substances and essential oils is altered by the applied temperature. CO2 extraction, on the other hand, is chemically closer to the original plant from which it originated, as it contains a wider range of botanical components.

Complete retention of the biological activity of the biological object
Low extraction temperature, with a CO2 critical temperature of 31.265°C and a critical pressure of 72.9 atm, which effectively prevents the oxidation, dissipation and reaction of heat-sensitive components and completely preserves the biological activity of biomass objects.

Meanwhile, substances with high boiling point, low volatility and easy pyrolysis can be extracted at a temperature lower than their boiling point.

High extraction efficiency and low energy consumption
Extraction and separation are combined into one process. When a supercritical fluid of CO2 saturated with solvents flows through the separator, the pressure drop causes the CO2 and the extraction fluid to quickly return to the two phases (gas-liquid separation) and separate immediately, with no material present. The phase change process does not require solvent recovery and is simple to operate.

Not only high extraction efficiency, but also low energy consumption, cost saving, in line with the trend of environmental protection and energy saving.

Simple operation, less time consuming, small footprint, friendly to the environment
The extraction operation is simple, and both pressure and temperature can be used as parameters to adjust the extraction process. Near the critical point, small changes in temperature and pressure can cause significant changes in CO2 density, resulting in changes in the solubility of the extracted substance. This can be achieved by controlling the temperature or pressure for extraction purposes. Fixed pressure, which can be used to separate the material by changing the temperature.

Is carbon dioxide extraction healthy?
The use of carbon dioxide provides a cleaner and healthier product.

Unlike solvents such as butane and hexane, CO2 extraction does not contain solvents or chemical residues. It is also recyclable and better for the planet in the long run.

Instead, the temperature is fixed and the pressure is reduced to separate the extract; therefore the process is short, time-consuming and takes up a small footprint. At the same time, it is truly environmentally friendly. The extract CO2 is recyclable and no waste CO2 is emitted causing the greenhouse effect! It is a truly "green" production process.

Polarity can be changed

The polarity of supercritical fluids can be changed. Under certain temperature conditions, it is possible to extract substances with different polarities by changing the pressure or adding the appropriate entraining agent, and a wide range of options is available.

https://blog.goo.ne.jp/steppermotors/e/100a940dd91b490c40c2e356bd4afa7a

https://www.weshare.hk/steppermotors/articles/4813943

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