What Is CO2 Cannabis Extraction and How Does It Work?
Supercritical CO2 extraction might sound like it came out of a Tom Clancy novel, but it has more to do with cannabis than with Cold War espionage.
If you have ever used a vaporizer pen, salve, cannabis-infused edible, or drinkable elixir, there is a good chance that product was made using supercritical fluid extraction technology. For many cannabis extraction professionals, CO2 extraction is the method of choice.
One of the main reasons why CO2 extraction is becoming more popular than its mainstream predecessor, the butane hash oil (BHO) extraction method, is the fact that it is much safer. BHO-related accidents were a regular occurrence in some U.S. jurisdictions less than a decade ago.
As a result, cannabis concentrate manufacturers are increasingly turning to safer, more sustainable alternatives like CO2 extraction to create full spectrum CBD oil, high-quality THC concentrates, and more.
What Is CO2 Extraction?
Most botanical extractions rely on some kind of solvent to eliminate plant matter and leave only pharmaceutically valuable compounds. In the case of cannabis extraction, solvents dissolve aromatic terpenes and biologically active cannabinoids from the plant material and carry them to a collection point.
Once broken down by the solvent’s chemical reaction, cannabinoids can be separated and used to create medically valuable cannabis infusions. The practical benefit of this approach is that the manufacturer can choose exactly which cannabinoid compounds—and how much—make their way into the final product.
Where butane extraction relies on putting highly flammable hydrocarbon gases under pressure, CO2 extraction uses carbon dioxide as a solvent.
The problem with carbon dioxide is that it does not naturally act as a solvent the way butane and propane do. However, this changes once the gas is subjected to extreme temperature and pressure.
Once CO2 reaches the “supercritical” state where it displays structures that fluctuate between being gaseous, liquid, and solid, it becomes as powerful a solvent as any hydrocarbon. Many different gases can be used in this way, but carbon dioxide is the most common.
Before the cannabis industry existed, supercritical CO2 extraction was a common method for coffee decaffeination and essential oil extraction for perfume-making. It remains a safe, sustainable, and relatively inexpensive way to extract valuable organic compounds from plant material.
Why Choose CO2 Extraction?
Cannabis concentrates are well-known throughout the cannabis community for their strength and potency. CO2 extraction is one of the principal ways manufacturers turn fresh, green cannabis into a highly concentrated cannabinoid wax.
While the most famous cannabinoid compound is THC, researchers have identified more than 100 individual compounds in cannabis. Many of these have valuable therapeutic effects.
This allows manufacturers like Extract Labs to create full spectrum CBD oil that does not contain mind-altering THC. Using this kind of cannabis product does not result in feeling high but still offers the same therapeutic benefits as cannabis.
Compared with other popular extraction methods, CO2 extraction carries a few key benefits:
- CO2 Is Widely Available. Carbon dioxide naturally exists in the atmosphere and is part of the natural biology of almost every living organism on the planet.
- CO2 Is Safe to Use. Among non-polar solvents, carbon dioxide is largely considered one of the safest available. CO2 accidents are far rarer than butane and propane explosions.
- CO2 Solubility Changes with Pressure. This allows supercritical CO2 extraction engineers to focus on isolating different biomolecules based on the desired product outcome. Increasing or decreasing the pressure changes which particular terpenes and cannabinoids come out of the process.
- CO2 Reaches Supercritical State Easily. Although the technical description of supercriticality sounds complicated to achieve, CO2 under pressure can reach this state at 90° Fahrenheit. This makes equipping an extract lab much easier than with many other supercritical fluid alternatives.
The CO2 Extraction Process Explained
Although the fundamental principles at work when conducting a CO2 extraction are simple, the process requires specialized equipment and training. This is especially true when designing large-scale industrial solutions to create mass quantities of product.
The first step in CO2 extraction involves taking carbon dioxide in its natural, gaseous state and subjecting it to extremely low temperatures at high pressure. This turns the gas into a liquid, which is necessary to prepare it for the transition to its supercritical state as gaseous CO2 cannot go supercritical.
Next, the fluid is heated to an appropriate temperature, and the pressure is increased further. If done right, the result will be a supercritical CO2 mixture.
This supercritical CO2 fluid is then passed through a chamber containing raw cannabis. The unique properties of the supercritical fluid make it act like a solvent, gently dissolving the oils out of the cannabis plant matter while capturing its essential active compounds.
The cannabis-enriched supercritical fluid is then pumped into a separation vessel. Pressure and temperature gradients separate out the various compounds, which sit atop one another like oil does on water. In technical terms, they become immiscible fluids.
The final step involves separating out the carbon dioxide by placing the fluids in a different chamber and letting the mixture stabilize back into gas. Industrial-scale manufacturers re-use this gas for the next extraction, which is why most manufacturers use “closed-loop extraction” equipment for this purpose.
Customizability and Secondary Processes
One of the things that make supercritical CO2 extraction so attractive to cannabis manufacturers is its customizability. Depending on the type of product desired, manufacturers can include additional refinement processes like winterization without having to invest in an entirely new extraction setup.
This means that CO2 extraction methods can be used to make everything from smokable cannabis waxes to delicious therapeutic edibles. CO2 extraction is also a safe and effective way to make medical-quality full spectrum CBD oil. It remains one of the most popular cannabis extraction methods in the industry, thanks to the combination of safety and cost-effectiveness.