SFE

Supercritical Fluid Extraction (SFE)

A solvent in its supercritical state is pumped and gets in contact with a solid or liquid substrate. At those conditions some compounds are solubilized and removed with the solvent. Through an expansion valve, pressure is reduced, therefore the compounds become insoluble and are separated from the solvent, which can be recycled.

In processes with cosolvents, a liquid is mixed with the supercritical solvent before getting in contact with the substrate. Thus, the solubilization power of the mixture is modified compared to the pure solvent, and other compounds can be extracted. In the separation, an additional step is required to remove the liquid cosolvent.

CO₂ is a nonpolar solvent, so it extracts preferentially nonpolar compounds. Polar cosolvents are used to increase the extraction of polar compounds present in the substrate.