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What are Supercritical Fluids? Properties and applications

What are Supercritical Fluids? Its properties and applications

Science and technology are constantly evolving, and one of the fields that has attracted a lot of attention in recent years is supercritical fluids. This concept, while it may seem complicated at first, has incredible potential to transform industry and scientific research. In this article, we will explain what supercritical fluids are, their properties and applications.

What are Supercritical Fluids?

A supercritical fluid is a substance that is in a state where it is neither liquid nor gas, but has properties of both. This occurs when a fluid is subjected to temperatures and pressures above its critical point, a state in which the differences between the liquid and gas phases disappear. In this condition, supercritical fluids have the ability to dissolve substances like a liquid, but can also flow and diffuse like a gas.

Carbon dioxide (CO2) is one of the most widely used supercritical fluids due to its relatively low temperature and critical pressure, as well as being chemically inert and non-toxic.

Properties of Supercritical Fluids

The properties that supercritical fluids have are:

  • Adjustable density: by modifying the pressure and temperature the density of CO₂ can be adjusted, this allows to control its capacity to dissolve different substances and its behavior in extraction and selective separation processes.
  • Isolation: to isolate the extract from a CO₂ extraction, a CO2 depressurization process is carried out. During this process, the supercritical CO₂ fluid undergoes a phase change to the gaseous state. This transition causes a significant decrease in CO2 density, resulting in the separation of dissolved compounds from the extraction fluid. The gaseous CO2 can escape from the system, leaving the extract free of contaminants in the extraction fluid, ensuring the purity of the final product.
  • Selective fractionation: with the ability to adjust the density of the supercritical fluids by precise changes in pressure and temperature, selective separation of different compounds in the various separators of the system is achieved. This approach optimizes the separation process, ensuring the purity and quality of the final products.
  • Recyclable:After use in extraction or synthesis processes, CO₂ can be easily recovered by depressurization and cooling, making it economically viable and sustainable.
  • Adjustable polarity: the polarity of CO₂ can be adjusted by adding a solvent of higher polarity, such as ethanol. Small amounts of more polar solvents can have a significant impact on the compounds being extracted.
  • Environmental responsibility: The use of supercritical fluids is considered environmentally friendly because it is non-toxic, non-flammable and fully recyclable. In addition, processes using supercritical fluids often require moderate temperatures and pressures, which reduces energy consumption.

Current Applications of Supercritical Fluids

Supercritical fluids are being used in a wide range of applications due to their unique properties. Some of the most common applications include:

  1. Decaffeination of coffee and tea
  2. Cannabis extraction
  3. Wool lanolin extraction
  4. Hop extraction
  5. Deodorization of oils and fats
  6. Decholesterization of egg yolk and animal tissues
  7. Food colorants and pigments
  8. Tobacco denicotinization
  9. Encapsulation of bioactive compounds such as drugs and nutrients.


Supercritical fluids are revolutionizing several fields, combining properties of liquids and gases to offer innovative solutions. In addition, their ability to dissolve, extract and clean efficiently and sustainably makes them ideal for applications in industries such as pharmaceuticals, food and advanced materials production.