Safe and Effective CO2 Extraction Methods

As more and more cannabis consumers purchase extracts, processors are constantly striving to find better and safer extraction methods. While various extraction methods still exist, the current winner seems to be supercritical CO2 extraction for cannabis products.
What is supercritical carbon dioxide extraction?

Supercritical CO2 extraction is the use of controlled temperature and pressure to create a phase (or state of matter) change in carbon dioxide (CO2) for the purpose of extracting cannabis plant material while maintaining the integrity and quantity of terpenes in the plant material. It also protects the cannabinoids from decarboxylation during the extraction process.The phase change in CO2 (e.g., from gas to liquid) allows you to separate different weights of plant material during the extraction process.

Why use supercritical CO2 in cannabis extraction?

Supercritical carbon dioxide (sCO2) is a variable state of carbon dioxide that is held at or above the liquid-vapor critical point (the maximum temperature and pressure at which a substance can coexist as a liquid and vapor equilibrium). According to scientists at Perdue University, the critical temperature of carbon dioxide is about 88 degrees Fahrenheit and the critical pressure is about 1,073 psi (pounds per square inch). When placed at pressures higher than 1,073 psi, carbon dioxide becomes what is known as a "supercritical fluid.

In this state, supercritical fluids (SCFs) have a density like a liquid, a viscosity like a gas, and a diffusivity that is somewhere between a liquid and a gas. In other words, supercritical carbon dioxide expands to fill its container as if it were in the form of a gas, but with the density of a liquid. This supercritical carbon dioxide liquid is used to remove the essential oil from the cannabis plant (or any other plant) without leaving any residue. Supercritical CO2 is cleaner and more environmentally friendly than many other solvents, so it's better for consumers and our planet. That's why socially conscious cannabis extractors choose to use CO2 supercritical fluids.

Often used in commercial cannabis extraction labs, CO2 is a "tunable solvent" (meaning that the dissolution strength of a CO2 supercritical fluid can be gradually adjusted by making slight adjustments to its density). Supercritical CO2 extraction is the safest and cleanest method of commercially extracting cannabis oil from the plant, and it can be used to make a variety of end products.
Advantages of using carbon dioxide as a solvent

There are many advantages to using carbon dioxide as a solvent in the cannabis extraction process.

Compared to traditional solvents, carbon dioxide is relatively inexpensive, non-toxic, non-flammable and inert (chemically inactive). It also has the distinct advantage of being able to diffuse through the cannabis plant material like a gas and dissolve the plant material like a liquid. In addition, CO2 leaves less residue after use in the extraction process compared to solvents such as butane. Finally, CO2 is readily available and almost pure and easily accessible.
What are the advantages of supercritical CO2 extraction?

Supercritical CO2 extraction is currently the "gold standard" of cannabis extraction methods because it is cleaner, more efficient, and safer than other extraction methods. Butane extraction, for example, can leave traces of heavy metals. In contrast, supercritical carbon dioxide extraction yields the highest purity cannabis oil, waxes and rosin with no residual solvent. In addition, although CO 2 is a greenhouse gas (a contributor to global warming), it does not cause any increase in greenhouse gas emissions when it is removed from the environment, used in the extraction process, and vented back into the environment.

Another advantage of supercritical CO2 extraction is that it allows for the separation of individual compounds during the extraction process. Large commercial plants that use supercritical CO2 extraction are also common in the food industry. Interesting fact: Coffee decaffeination uses supercritical CO2 extraction equipment to separate caffeine from coffee.
Measuring the Effectiveness of Extraction Processes

Overall yield is actually not very relevant when measuring the effectiveness of any extraction method.

Yield data is often collected because it helps to establish a baseline for financial models, determine return on investment, etc. However, the yield of any extraction process is dependent on the quality of the original raw material. The cannabinoid content of different strains of cannabis varies greatly, not only between indica and sativa, but there are unique cannabinoid profiles within each category. Generally, plants are specifically bred to produce high levels of THC or predominantly CBD, but of course there are many hybrids as well. The amount of total THC extracted provides a high concentration of THC compared to the amount present in the raw material.