What is a Supercritical Fluid?

A supercritical fluid (SCF) is any substance above its critical temperature and pressure; the fluid has the properties of both gas and liquid while not exhibiting a distinct liquid or gaseous phase. Thus, an SCF is,

• Dense like a liquid to dissolve materials

• Has low viscosity, high diffusivity, no surface tension like a gas

Carbon dioxide is the most commonly used supercritical fluid and becomes supercritical at 31^oC and 74 BAR. There are many applications for scCO₂, including decaffeination of coffee, extraction of natural products, and waterless textile dyeing.

Carbon dioxide is environmentally friendly, non-toxic and in our case most of the CO₂ is internally recycled with very little vented to the atmosphere. scCO₂ based operations represent a very “green” technology.

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It All Starts with Coffee

Supercritical... Coffee?

After its discovery, the first large scale use of supercritical fluids in extracting natural products was the decaffeination of coffee. Since then, many industries have made the switch to supercritical fluid. Producers of essential oils are finding supercritical fluids to be an excellent replacement for traditional methods that use hazardous chemicals.

Solvent Free extracts created with supercritical fluids are found in foods, fragrances, herbal extracts, natural medicines, aromatherapy… and the list goes on.

For more information about how supercritical fluid can improve YOUR process, visit the  Essentials Oils section of the Applied Separations website.

Environmentally Friendly Essential Oil Extractions

The use of essential oils has become "essential" for modern living. Essential oils can be primary ingredients in perfumes for cosmetics or soaps and detergents. They form the basis of the spices in our foods. Essential oils are the base for aromatherapy.

What if there was a way to extract essential oils quickly and efficiently, without compromising the quality of the extract? There is. Supercritical carbon dioxide.

With supercritical fluids:

• No Solvent residue. No health hazard. Maintains a "natural" state. 
• Mild Extraction Conditions – 31°C temperature 
• Fractionation - easy using only CO₂ - CO₂ is a "tunable solvent" – easily change your temperature/pressure to suit your material 

Supercritical CO₂ can also be used in conjunction with more traditional methods such as soaking perfume feedstocks in an organic solvent for a period of time. The organic solvents containing the extracted the perfumes (essential oils) and accompanying waxes is then decanted and evaporated, leaving a concrete. The essential oils can easily be separated from the wax with supercritical CO₂. Because of the low temperature, the process gives high recoveries.

Click here to see an example of a supercritical system for the extraction of essential oils.

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Replace Hexane in Your Essential Oil Extractions

Hexane is a commonly used solvent in natural products and essential oil extractions. But Hexane has been categorized as a hazardous air pollutant by the US EPA, and is included on their list of toxic chemicals. Despite best efforts, facilities using hexane may leak up to 6,000 pounds of hexane a day into the atmosphere. In addition, extracts will contain undesirable hexane residue.

The solution: Supercritical Fluid extractions.

• No hazardous waste
• No chemical residue
• No health hazard
• Environmentally friendly

Click here for information about supercritical fluids.

Click here for information about extracting essential oils with supercritical fluids.

“Green” Alternative to Soxhlet for Fat Determination in Food

Supercritical fluid extraction (SFE) was used to determine total fat and fat-soluble vitamins in Parmigiano cheese and salami. The results were compared with results obtained by traditional methods (Soxhlet). The quantity collected by SFE was statistically equivalent to the Soxhlet extraction.

For more information about the process or the specific application, contact Applied Separations
or visit the SCF section of the Applied Separations website.