Extraction

Extraction is the name given to any separation process in which one or more components of a mixture of substances (consisting of solid, liquid, or gaseous individual substances), the extraction material, is dissolved out with the aid of an extraction agent (solid, liquid, or gaseous).

The extracted substance, even if it is still in the solution, is called an extract. If the extracted substance is not altered (e.g. only dissolved or adsorbed), the extraction is a physical process; if the substance undergoes a chemical reaction, it is a chemical process.

If a solvent is used as the extracting agent, the substances to be extracted dissolve better in the pure solvent than in the mixture of substances; the solvent draws the substance, which is more soluble in it, from the mixture. Depending on the solubility of the substances, the inorganic solvents used are, for example, water and water vapor, acids, bases, and liquefied carbon dioxide. The organic solvents are, for example, alcohols, terpenes, diethyl ethers, vegetable oils, chlorinated hydrocarbons, or n-hexane. Pressure and temperature usually significantly increase the solubility of substances, which is why some extractions are carried out with a hot solvent and/or under pressure. An example of a cold extraction is the extraction of rock salt during salt extraction in salt domes.

Pfaudler supplies a complete range of standardized filters useful in chemical and pharmaceutical extraction systems.