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2023

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02

Detailed explanation of the advantages, disadvantages, applications, processes, and influencing factors of supercritical CO2 fluid extraction technology

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Supercritical fluid extraction (SFE) refers to the process of extracting specific components from liquids or solids to achieve extraction and separation by using supercritical fluid which has a high solubility of solute in supercritical state but a low solubility of solute in non supercritical state. Let's learn about the advantages and disadvantages, applications, processes, and influencing factors of supercritical CO2 fluid extraction technology together with the editor.

Supercritical fluid extraction (SFE) refers to the process of using supercritical fluids to have high solubility in the supercritical state but low solubility in the non-supercritical state, extracting specific components from liquids or extracting specific components from solids to achieve extraction and separation. Let's take a look at the advantages and disadvantages, applications, processes and influencing factors of supercritical CO2 fluid extraction technology.

Supercritical

         

Any pure substance, with the change of temperature and pressure, will correspondingly present three states of solid, liquid and gaseous, called material three states. The temperature and pressure values when the three states are converted to each other are called the triple point, and each chemically stable substance has an inherent critical point, that is, the density of the substance is equal to the critical point at this temperature and pressure. In the liquid state, the density is close, but the characteristics of the gas are retained. When the temperature and pressure exceed the temperature and pressure of the critical point, the substance enters a supercritical state, and the substance in the supercritical state is neither gaseous nor liquid, which is called a supercritical body.

 

Although there are many substances that can be used as supercritical fluids, only a very small number of solvents meet the requirements in terms of cheap and easy availability, low critical temperature and pressure, low latent heat of evaporation, safety and environmental protection. The temperature is 0-100 °C, the pressure is 2-10MPa, and the substances with low latent heat of vaporization include carbon dioxide (TC31.1 °C, Pc7.15MPa, latent heat of vaporization 25.25kJ/mol), propane (TC96.8 °C, Pc4.12MPa, latent heat of evaporation 15.1kJ/mol). Considering the low cost, easy availability, safety of use and other factors, carbon dioxide is considered to be a supercritical fluid suitable for extraction.

 

The density of supercritical fluid is very sensitive to changes in temperature and pressure, and its solubility is proportional to its density within a certain pressure range, so the solubility of substances in supercritical fluids can be changed by controlling temperature and pressure, especially near the critical point, small changes in temperature and pressure can lead to sudden changes in solute solubility of several orders of magnitude, which provides a research basis for the feasibility of fluid extraction technology.

 

Applications in sewage treatment

 

Because CO2 is chemically stable, non-toxic and non-corrosive, non-flammable and explosive, it is easier to achieve a critical state, and the critical temperature of carbon dioxide is 31.1 °C is relatively close to normal temperature, so it can be used for sewage treatment. Small changes in operating pressure or operating temperature near the critical point can cause large changes in the density of supercritical fluids, resulting in orders of magnitude changes in the solubility of carbon dioxide. The principle of supercritical carbon dioxide treatment sewage is to dissolve the pollutants in the sewage, and then reduce the pressure or increase the temperature, and separate the extractant and the pollutants in the low-density state, so as to achieve the effect of treating sewage.

 

NANTONG WISDOM SCFE

The Company has committed to the field of supercritical fluid extraction equipment for 30 years.