Super critical CO2 is an important commercial and industrial solvent due to its role in chemical extraction. In addition, CO2 is not toxic and compared to other chemical extraction methods, has much, much less environmental impact.
CO2 extraction takes place at a low temperature and extracts compounds from herbs and plants and leaves these compounds unaltered and undamaged by heat.
Because CO2 is gas at normal atmospheric pressure, it leaves no trace of itself in the final product. The equipment for CO2 extraction is expensive, which is reflected in the price of compounds obtained from the process.
The term "critical point" or "critical state" is sometimes used to denote specifically the vapor-liquid condition of a material and is monitored to the highest degree by temperature and pressure. The vapor-liquid critical point denotes the conditions above which distinct liquid and gas phases do not exist. Beyond this critical point, there is no distinction between the liquid and gas phases.
Super critical carbon dioxide reflects to carbon dioxide that is in a fluid state while also being at or above both its critical temperature and pressure, yielding rather uncommon properties. Carbon dioxide usually behaves as a gas in air at standard temperature and pressure or as a solid called dry ice when frozen. If the temperature and pressure are both increased from standard temperature and pressure to be at or above the critical point for carbon dioxide, it can adopt properties midway between a gas and a liquid.
The relatively low temperature of the process and the stability of CO2 also allows most compounds to be extracted with little damage.
By contrast, the cheaper chemical extraction method draws out organic compounds using chemicals, traces of which remain in the final product. This is not good.