How Does CO2 Extraction Actually Work?

cannabis for treatment (decoction, tincture, extract oil).

Cannabis and cannabis-derivatives are increasingly popular for medical and nutritional supplement use.

People rightly perceive them to be part of the natural pharmacopeia. As a healing herb, all-natural cannabis is suggested for various ailments.

Extracting the best parts of healing herbs into concentrated oils and extracts for use is a delicate process. There are several ways to concentrate and refine plant oils for use. Some methods are more or less efficient than others.

Common methods include simple decoctions and infusions, organic solvents, pressurization and more. For people seeking the purest, most concentrated oils, a natural method like CO2 extraction (Carbon Dioxide) makes sense.

There is little to no chemical residue to speak of and essential phytonutrients are preserved.

Read on to learn more.

Extraction Methods Primer

Common methods like decoction (boiling to concentrate) and infusion (soaking to extract the compounds, like tea) destroy vital nutrients or leave behind certain compounds. Extractions, separations and other operations are more advanced chemical processes.

The words "organic solvents" do not refer to a condition, such as "organically grown", but refer to a set of chemical compounds. Solvents such as butane, propane, and ethanol are organic. Herbs are placed in the solution, then the fluid is drawn out in a vacuum.

The result is a concentrated product. The solvent is then recycled for use. A small amount remains in the product. Not many people want to put lighter fluid, heater fuel or gasoline additive into their bodies, no matter how minuscule the amount.

Conventional organic solvents are often regulated as volatile organic compounds (VOCs). They can pose a number of environmental concerns, handling, and disposal issues. You may be familiar with the many lingering effects of common dry-cleaning fluid, for example.

CO2 Is a Green Extraction Method

Supercritical carbon dioxide is an attractive alternative to traditional organic solvents. Advantages include:

  • Inert
  • Non-toxic
  • Non-flammable
  • Low-cost
  • Works at near-ambient temps

CO2 leaves little residue in products compared to conventional solvents. It is easily available in large quantities of purified gas. Compared to using hydrocarbons, it is safe for the environment, easy to work with and creates a superior product.

Most importantly, CO2 is a generally recognized as safe (GRAS) solvent. GRAS is the FDA standard designation that a chemical or substance added to food is considered safe by experts. It means that it is exempt from the usual Federal Food, Drug, and Cosmetic Act (FFDCA) food additive requirements.

How Does the Extraction Process Work?

In traditional steam distillation, heated water vapor is pushed through the herbal matter and the volatiles are carried through the steam. They are then allowed to condense and cool. Unfortunately, heat tends to damage many active ingredients and removing the water vapor further weakens the lifespan of the concentrate.

Hydrocarbon solvents work in virtually the same way. Butane is used to dissolve and suspend the wanted absolutes, then the butane is extracted, leaving behind the wanted compounds. Unfortunately, some residue remains and the process can be dangerous.

Other methods for extracting natural oils include cold pressing (for olives, nuts, and other oily fruits) and cold water extraction (for fruits.) Neither of these is suitable for cannabis.

The CO2 Extraction Process

There are two steps:

  • First, the ground solids are fed into the extractor and the heated, pressurized, supercritical CO2 in is agitated with the material to extract the desired compounds. At this point the solvent neither a liquid nor a gas. It acts as a liquid at this point.
  • Second, the CO2 is separated and removed. Usually, this is done by reducing temperature and pressure. CO2 is easily purged as a gas. An external agent may be used to absorb or adsorb CO2 so that no pressure change is required.

However, use of an external agent requires an additional step to remove the external agent. In industrial uses, this is the process associated with better quality decaffeinated coffee.

Why CO2 Extraction?

The use of carbon dioxide under pressure can replace steam distillation and hydrocarbon solvents. Supercritical CO2 extraction uses CO2 pressurized to 1100 psi and just above 89 F. Under these conditions, it has both the properties of a liquid and a gas.

Through precise control of time, temperature, pressure and flow rates, it is possible to determine exactly which components of a complex natural material are extracted. An advantage to using a CO2 extractor is that thermal degradation of the compounds is not a concern. Additionally, CO2 is nontoxic if there is a residue present.

Product yields are greater and product residues less with supercritical CO2 extraction. Thermal decomposition of materials almost never occurs due to the relatively mild processing temperatures, and very precise control of inputs allows for specific compound extraction.

Extraction Equipment

Fine tuning the extraction process for specific compounds is possible. However, it is unlikely that a homemade rig will meet rigorous safety and quality standards. A safety certification is absolutely necessary for the pressure vessel, fittings, piping and valves used for a supercritical CO2 extractor.

Additionally, given the versatility of this method, complete phase control for separating compounds is a desired feature. Unlike steam distillation, which is somewhat like a wrecking ball, CO2 extraction works more delicately, like sculptor's chisel.

First-class equipment allows minor adjustments, whether your system is concentrating essential oils from a metric ton of flowers or a mere handful.

The Right Extraction for Your Needs

CO2 extraction offers substantial advantages to solvent-based extraction. It is safe, residue-free and customizable.

Compared to other common methods of essential oil extraction, the process is simple and involves no toxic chemicals. Specialized equipment to allow pressurization and temperature control is all that is needed.

The simple process involves breaking down herbal matter in a container with heated and pressurized CO2. CO2 is allowed to then dissipate into the atmosphere or is recovered for another use.

Questions or comments about how CO2 extraction works and how Vitalis Extraction Technology is ready to ship several models? Please comment below.

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