Supercritical fluid extraction (SFE) is a rapidly developing separation method in industrial production in recent years, which is widely used in food, pharmaceutical, chemical and other fields due to its high efficiency and environmental protection characteristics. The core of this technology is to use the special characteristics of fluid in the supercritical state to achieve efficient extraction of substances.

Fundamental properties of supercritical fluids

When the temperature and pressure of a substance exceed its critical point, it enters a supercritical state. In this state, the fluid has both the high diffusivity of gas and the high solubility of liquid. This allows the supercritical fluid to quickly penetrate into the micropores of the solid substance and dissolve the target compounds therein, enabling efficient extraction.

Carbon dioxide (CO₂) is the most widely used fluid in supercritical extraction. Due to its low critical temperature (31.1°C) and non-toxic and harmless nature, CO₂ is ideal for the extraction of heat-sensitive substances such as plant essential oils and medicinal active ingredients. At the same time, CO₂ is easily vaporized directly by reducing pressure after extraction, avoiding the problem of solvent residue and further ensuring the purity of the product.

Application field

1. Food industry: SFE technology plays an important role in the production of food additives. For example, the removal of caffeine, the extraction of plant extracts (such as sunflower oil and capsaicin), etc. Compared with traditional extraction methods, SFE avoids the destruction of active ingredients by high temperatures, while the product is purer.

2. Chemical field: SFE is used for the purification of fine chemical products and the extraction of high value-added substances, such as spices, active ingredients in cosmetics.