What means supercritical?

A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. It can diffuse through solids like a gas, and dissolve materials like a liquid. Additionally, close to the critical point, small changes in pressure or temperature result in large changes in density, allowing many properties to be "tuned".



What that is used for?

The supercritical fluids have been used at the industrial stage for 30 years.

Two fluids are mainly used: the carbon dioxide (C02) and water.
> Supercritical C02 : allows to conceive processes at temperatures close to the room temperature, thus avoiding any thermal degradation of made up most fragile without production of polluting effluents.
Realizable technological operations with CO2: extraction/separation/impregnation/synthesis/reaction

> Supercritical water : oxidation/synthesis: in supercritical conditions (CP > 221 bar and CT > 374 C°), water precipitate minerals and become a solvent of the organic matter.
In this environment, we can destroy by ultimate oxidation organic wastes without rejection than CO2 and water. Moreover, the reaction automatically discusses and is thus less energy-consuming that the incineration.
Many advanced materials can also be prepared by hydrothermal synthesis, particularly mineral powders intended for making ceramics with high efficiencies and nano-structured inorganic materials.

How to use it?

Example of compounds extraction
Fluid used: Sc (supercritical) C02
1) C02 is compressed and heated via an autoclave beyond his critical point: 74 Bars and 31°C
2) Beyond the critical point, C02 evolves in supercritical phase and then acquires solvent properties. These solvent properties enable him to extract the compound from the matrix.
3) The temperature and the pressure are lowered and the C02 return in a gas state, thus releasing the compound.

• Environment
• Food industries
• Pharmaceutical
• Cosmetics
• Materials
• Nuclear