![]() ![]() The densities and viscosity of a supercritical fluid are subject to change when pressure or temperature are tampered with, and the supercritical fluid of a substance can have very different properties than the regular fluids. Supercritical fluids have no surface tension because they are not subject to the vapor-liquid boundary so no molecules have the attraction to the interior of the liquid. The Mole Fraction Solubility is simply the ratio of the sublimation (or vapor pressure) to the total gas pressure. As can be noted from the Mole Fraction Solubility. It becomes especially easy to dissolve liquids and solids such as these in a supercritical fluid because of the high density. ![]() Volatile liquids and solids, or liquids and solids with a high vapor pressure or low boiling point, are soluble in gas. However, it is possible to go from a gas to a liquid without crossing the boundary between the vapor and liquid phase using a supercritical fluid just by lowering the temperature of the liquid (Observe phase diagram below). Supercritical fluids have the low viscosityof a gas and the high density of a liquid, making it impossible to liquefy the matter using any amount of pressure. ![]() In 1822 Baron Charles Cagniard de la Tour discovered supercritical fluids while conducting experiments involving the discontinuities of the sound of a flint ball in a sealed cannon barrel filled with various fluids at various temperatures ("Charles Cagniard de la Tour"). This stage is characterized by the inability to distinguish whether the matter is a liquid or a gas, as a result, Supercritical fluids (SCF) do not have a definite phase. Matter can be pushed to temperatures and pressures beyond those of its critical point. We can model the process to make larger scale designs.\) We also have the infrastructure to evaluate the physical-chemical and microbiological quality of the extracts and the exhausted raw materials. We have facilities of different sizes to carry out extraction tests on all types of materials ( Figure 2) and for their pre-treatment ( Figure 3). We do have experience on supercritical extraction of oils rich in bioactive compounds from plants, microalgae and residues for their revalorization extraction of caffeine from coffee grounds oleorresin from paprika cleaning of metal parts production of aroma-free cork cocoa defatting…We are now working on hemp. There is a high technological maturity and any application could be taken to an industrial scale in a short period of time. Given the high costs of the installations, the supercritical extraction is a process suitable for high production and/or relatively high unit selling price. Therefore, supercritical extraction can be considered an intensive process. The solvent is easily recovered and recirculated. Hence, the subsequent purification process is simpler or even unnecessary, compared to conventional extractions which require complex downstream.Ĥ. The process is faster, more selective and easier than with organic solvents. The aroma and taste of the extracts are more natural ģ. After extraction, CO 2 can be removed in gaseous form without leaving no residues in the matrix or in the extract Ģ. The pressure varies between 100 and 500 bar, depending on the type of extract.ġ. In those cases, higher temperatures are required to assist in desorption (up to 80☌). In general terms, supercritical CO 2 extraction processes are run at temperatures of 35-40☌, except in processes where the solute is strongly adsorbed. If the extracted solute is the product of interest, the raw material may require grinding to increase the yield and speed of extraction. The addition of water to facilitate the extraction is frequent. Generally, a pre-treatment of the solid material is required. In this case, the solvent circuit can be operated at almost constant pressure.įigure 1. Alternatively, the solute can be separated from the supercritical solvent by adsorption, absorption or with a membrane. Then, the solvent loaded with the extract is evacuated from the extractor and fed to the separator, where the pressure is reduced so that the solute is not soluble and precipitates. First, the supercritical CO 2 flows through the raw material and dissolves the extractable components. In fact, it is considered a GRAS solvent.Īll supercritical fluid extraction (SFE) processes consist of two stages (see scheme on Figure 1). It is a "green" solvent found in the atmosphere, in food and beverages and of which no minimum content needs to be set in the extracts, so it can be used safely. Of all the supercritical fluids that have been studied, carbon dioxide (CO 2) is the most used due to its low critical temperature (T C = 31✬) and pressure (P C = 74 bar), non-toxicity, availability and low cost. ![]()
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