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Guide to CO2 Extraction of Cannabis Oil: Basics and 8 steps

What is CO2 Cannabis Extraction
What is CO2 Cannabis Extraction

What is Cannabinoids?

Cannabinoids are a fundamental part of the cannabis plant. Of over 480 different compounds present in the plant, only around 66 are termed cannabinoids. The most well-known among these compounds is the delta-9-tetrahydrocannabinol (Δ9-THC), which is the main psychoactive ingredient in cannabis. Cannabidiol (CBD) is another important component, which makes up about 40% of the plant resin extract.

These naturally occurring chemical compounds contribute to the myriad effects cannabis consumers experience when they light up a joint, eat an edible, or drop a cannabis-infused tincture under their tongue. Distinct cannabinoids can induce effects as far-ranging as euphoria, pain relief, paranoia, sleepiness, and even increased appetite—yes, certain cannabinoids can even cause the munchies.

Classes of cannabinoids

The cannabinoids are separated into the following subclasses:

  • Cannabigerols (CBG)
  • Cannabichromenes (CBC)
  • Cannabidiol (CBD)
  • Tetrahydrocannabinol (THC)
  • Cannabinol (CBN)
  • Cannabinodiol (CBDL)
  • Other cannabinoids including cannabicyclol (CBL), cannabielsoin (CBE) and cannabitriol (CBT)

Effects of cannabinoids

Cannabinoids exert their effects by interacting with specific cannabinoid receptors present on the surface of cells. These receptors are found in different parts of the central nervous system and the two main types of cannabinoid receptors in the body are CB1 and CB2. These compounds don’t occur naturally in plants or people but are synthesized using chemical processes. There are more than 200 synthetic cannabinoids, nearly all of which are designed to exert powerful effects on the body’s cannabinoid receptors. This cannabinoid-like chemical and others that were later discovered are referred to as endocannabinoids.

Synthetic cannabinoids can also be made by chemically manipulating CBD, which can be extracted from industrial hemp. Another example of synthetic cannabinoid production is the “pharming” of cannabinoids using brewer’s yeast, which acts as a medium for growth—bacteria and algae have been used as mediums too.

Read More: Cannabinoids Wikipedia

Differences between cannabinoids

The main way in which the cannabinoids are differentiated is based on their degree of psychoactivity.

  • For example, CBG, CBC and CBD are not known to be psycholgically active agents whereas THC, CBN and CBDL along with some other cannabinoids are known to have varying degrees of psychoactivity.
  • The most abundant of the cannabinoids is CBD, which is thought to have anti-anxiety effects, possibly counteracting the psychoactive effects of THC.
  • When THC is exposed to the air, it becomes oxidized and forms CBN which also interacts with THC to lessen its impact.
    This is why cannabis that has been left out unused will has less potent effects when smoked, due to the increased CBN to THC ratio.

Read MoreCO2 Extraction Machine: 3 Types, 4 Tips, 5 Notes, Top 6 Apps

CO2 Essential Oil Extraction Equipment
2100L CO2 Extraction Equipment

What is CO2 Extraction of Cannabinoids?

Extraction is a separation technique seeking to separate a target compound from its matrix. This is not the same as chromatography, filtration or distillation. The goal is to selectively remove the compounds desired from the resin. This is done in a number of methods that are performed to create distillate and isolate extracts from botanical biomass.

Supercritical (sc-CO2) extraction has been around for decades, appearing first in the 1980s and 90s as a cleaner and more viable alternative to other methods of separation and extraction.
Supercritical CO2 extraction is used in a wide array of extraction systems from essential oils to decaffeinated coffee. The most famous and successful industrial process for supercritical CO2 extraction is the coffee decaffeination process. It can also be used to extract any botanical oil from any plant material.

To put it simply, CO2 extraction uses pressurized carbon dioxide in select temperatures to pull desired cannabinoids from hemp biomass. With the combination of special temperatures and pressures, CO2 reaches what is called a supercritical state. This is a crucial factor in the CBD extraction process that allows for a complete extraction at an efficient throughput.

8 steps of Supercritical CO2 Cannabis Oil Extraction Process

Work Principle

A supercritical CO2 extraction machine uses CO2 at an elevated temperature and pressure(supercritical CO2 fluid) to extract soluble compounds from natural products. Carbon dioxide above the critical temperature (31ºC) and pressure (1071 psi) become a supercritical fluid, which has an increased capacity for solubilizing non-polar compounds.
Under supercritical conditions, CO2 behaves much like fluid solvents similar to hexane in terms of its solubility selectivity. This higher solubility means a highly efficient extraction of desirable cannabinoids. Raising the temperature and pressure of the liquid CO2 even further provides highly efficient extractions of oils in a shorter period of time.
As it passes through the biomass, the supercritical fluid breaks down the non-polar compounds and dissolves them into the fluid. After the separation of desired cannabinoids, the fluid CO2 is reverted back to a gaseous state leaving a “crude oil” containing CBD, terpenes, and residual plant materials ready for distillation and product formulation.

8 steps

The following is a very basic outline of how the ScCO2 process works:

  1. An extractor chamber is filled with ground cannabis/hemp material (called trim).
  2. A pump forces pressurised carbon dioxide gas at the optimum temperature (ScCO2) into the extractor chamber.
  3. The supercritical carbon dioxide interacts with the cannabis, dissolving the cannabinoid compounds it contains.
  4. The supercritical CO2 carries the cannabis oil particles past a pressure release valve to a cyclonic separator.
  5. In the separator, the pressure is lower and the carbon dioxide and cannabis oil separates.
  6. The carbon dioxide rises and is routed back to the CO2 tank for reuse in the case of a closed loop system.
  7. The cannabis oil, waxes and resins descends in the separator where they are captured by a collection vessel.
  8. The resulting substance is processed further into various products, such as CBD-rich “cannabis oil”, free of any solvents.

Works Cited: A Guide To CO2 Extraction Of Cannabis Oil

CO2 extraction process
600L supercritical CO2 extraction machine

Read More: CO2 Extraction Process: Basics, 5 Advantages, 7 Features, 4 Applications

What’s The Difference Between An Essential Oil: CO2 Extracts Vs Essential Oils
What’s The Difference Between An Essential Oil: CO2 Extracts Vs Essential Oils

Top 4 Pros of CO2 Extraction Process

Clean and Green

As far as non-polar solvents are concerned, CO2 is among the safest. CO2 is a naturally occurring compound. It exists all around us and our bodies produce it. CO2 extraction systems are by far the cleanest for consumers, producers, and the environment alike.


Supercritical CO2 fluid kills any microbial bacteria, mold, mildew, or insect mites that shouldn’t be in your weed in the first place.


While pricey, supercritical extractors compare well to the cost of other solvent-based approaches when taking into account the safety equipment and special facilities legally required in some countries for working with flammable solvents.

Safest Products

Supercritical CO2 extraction is that there’s no need to use potentially harmful chemicals in the process.Because there are no chemical denaturants or volatile solvents left over in a ScCO2 product, it is undoubtedly the safest extraction process to create a safe product for consumers. The absence of these extra chemicals makes supercritical CO2 concentrates safer to consume and tastier to experience thanks to the preservation of terpene aromas.