We have written about solvent and solvent-free extraction methods on previous posts. Many cannabis users prefer solvent-free methods because they don’t want CBD products that may contain additional chemicals and residues.

CO2 extraction of CBD is a solvent-free extraction method that is very efficient for CBD extraction. In addition, this process is equally efficient for the extraction of other cannabinoids and essential oils. Furthermore, CO2 extraction for CBD has antibacterial properties and according to some sources it’s a more effective method to extract terpenes and cannabinoids than solvent-based extraction methods.

It might sound strange to hear about supercritical CO2 extraction, but it’s actually a very common extraction method in the herbal and food supplement industry. For example, decaffeinated coffee uses this method to extract the caffeine from the coffee seeds.

Moreover, CO2 is also safer than other popular extraction methods that use dangerous gases such as butane.  Perhaps you have read about THC extraction using butane and explosions (most of times because it’s done improperly by inexperience people).

What’s CO2 supercritical extraction?

Supercritical CO2 is a fluid state of CO2, in this state CO2 keeps both gas and liquid properties. This state is obtained when carbon dioxide is held above its critical temperature and critical pressure. As state in Wikipedia, “ it expands to fill its container like a gas but with a density like that of a liquid”.

Carbon dioxide acts as a solvent by extracting cannabinoids and essential oils from the plant material. In addition, it acts as a versatile solvent that is much safer than butane extraction methods.

Even though carbon dioxide acts as a solvent, do not confuse it with chemical solvent extraction methods such as ethanol or butane. In other words, carbon dioxide acts as a solvent but without any contamination of the cannabis byproducts. Therefore, CO2 extraction of CBD is the perfect method for users looking for clean, toxic-free cannabis byproducts.

How Does CO2 Extraction of CBD Work?

The hemp is placed inside a container that goes inside a special chamber. After that, CO2 that is caught from the air is pumped into the chamber. Then, the chamber is high pressured.

The carbon dioxide changes to its fluid state and circulates in the chamber. When this process is completed (it takes several hours), the liquid is taken to another chamber to separate the carbon dioxide from the oil. Once the carbon dioxide is evaporated, the cannabis byproduct is ready. The CBD oil usually is thicker than other cannabis byproducts and it has a brown-goldish color.

This process is the purest method as chemical solvents are never used in the extraction process. The following video by Endoca explains how CBD is extracted with supercritical CO2:

CBD extraction using supercritical CO2.

Components of the Extraction System

The extraction system has three components: an accumulator, extraction vessel and a separator.

As explained above, the extraction vessel is filled with cannabis plant material. In the accumulator, there’s CO2 in its liquid form that is used to extract the essential oils from the cannabis plant material.

Then, the cannabis oil flows from the extraction vessel to the separator. The separator has a lower pressure and due to this change of pressure, the CBD oil separates from the less dense CO2. Then, the CBD oil is removed from the separator for further processing.

Why Using Supercritical CO2 for CBD Extraction?

According to one study published in the Journal of Organic Chemistry and entitled “Supercritical carbon dioxide: a solvent like no other” supercritical CO2 could be a potential replacement for volatile organic compounds (VOCs). Moreover, supercritical CO2 for cannabis extraction is often defined as a “green extraction method”.

In other words, CO2 extraction of CBD doesn’t produce chemical waste and therefore it’s defined as a green extraction method. On the other hand, CO2 extraction isn’t cheap, and it requires the investment in expensive equipment.