Cannabis concentrates and extracts are the foundation for many of your favorite cannabis infused products including vapes, tinctures, edibles, and topicals. CO2 extracts are safe to use and pure.
While there are many ways to commercially extract the cannabis resin from the plant, one of the most effective ways is through supercritical carbon dioxide (CO2) extraction. Our CO2 extraction guide covers the basics of CO2 extracts and how they are made.
What Are CO2 Extracts?
CO2 extracts are made using the supercritical CO2 extraction process. Cannabis processors can strip the cannabis plant of its bioactive compounds including cannabinoids, terpenes, and other essential oils, which have many therapeutic uses.
From the cannabis plant’s trichomes, manufacturers can create a variety of extract-based products, particularly vapes and cannabinoid isolates. CO2 as a solvent can reap a high concentration of compounds for recreational and medicinal use.
What Is Supercritical CO2?
Supercritical CO2 extraction is commonly used in the botanical extraction industry, which has extended into the cannabis market in the processing of THC-rich biomass. Fully automated extraction solutions can be used for a variety of oil extractions, including:
Botanical fragrance oils
This method of extraction has gained support among the industry as a safe and effective extraction type. In this extraction process, manufacturers use CO2 in its supercritical state. They expose the gas to extreme pressures and temperatures. As a result, the CO2 solvent turns into a state with characteristics of a liquid and a gas.
Carbon dioxide has a critical temperature of about 88º F and a critical pressure of about 1073 pounds per square inch (psi). For reference, CO2 is a gas at normal temperatures and pressures. It becomes a liquid at 60.4 psi and a solid (dry ice) at -109.3º F.
When cannabis extraction technicians raise the pressure in the closed-loop system, CO2 can become a supercritical fluid. It has a high density like a liquid and high diffusivity like a gas. Essentially, when it fills a container, it expands until it fills it completely, all while separating the plant’s trichomes.
In its supercritical state, these supercritical fluids can easily dissolve and separate cannabinoids and terpenoids from the raw cannabis plant material. Many processors turn to supercritical CO2 for its relatively safe and environmentally-friendly characteristics.
One of the downsides of making CO2 extracts is the high cost of the extraction equipment. CO2 extraction systems can cost tens of thousands of dollars for entry-level units and hundreds of thousands of dollars for high-grade systems capable of handling high volumes of biomass.
On the other hand, CO2 extracts can be cost-effective in the long run, since the solvent is relatively inexpensive and there are fewer safety equipment and facility requirements compared to using flammable solvents such as hydrocarbons (propane and butane) or ethanol.
It is important to note that CO2 extractions take place in pressurized environments that require experienced operators to set precise parameters for safety. For this reason, it is critical to invest in high-quality equipment and extensive operator training when dealing with this method of extraction.
Benefits of Using CO2 Extraction
Carbon dioxide as a solvent is naturally found in the atmosphere as a gas. For its industrial use, it can be frozen and compressed into a liquid and converted into a supercritical state when ready for cannabis extraction. Many cannabis companies are turning to this solvent for its many production benefits.
Carbon dioxide is found naturally all around us. We use it to live and breathe, so naturally it is seen as a safe and eco-friendly alternative to other types of solvents. Other types of solvents can be flammable and have stricter storage and facility requirements.
Compared to other extraction solvents, many manufacturers consider this non-polar solvent to be one of the safest solvents to use. CO2 is approved by the Food and Drug Administration (FDA) and is generally regarded as safe (GRAS) for industrial extractions. In addition, it will not leave any residual solvents in the final product after the production process.
During the extraction process, the lower the temperature used, the better processors can preserve the plant’s cannabinoids and terpenes. Terpenes are thought to create an “entourage effect” that can increase the health benefits of cannabinoids and decrease the side effects. CO2 can reach a supercritical state without needing to go beyond 90º F, so extractions can preserve more of the temperature-sensitive components such as terpenes, the plant’s aromatic molecules.
With subtle changes in pressure and temperature in the closed-loop system, CO2’s solubility changes, allowing it to separate and collect different types of bioactive compounds from the cannabis plant material. By manipulating the temperature and pressure parameters, cannabis processors can target and isolate specific cannabinoids, terpenes, and other essential oils.
CO2 is a greenhouse gas that absorbs and radiates heat. In the environment, the excessive increase in CO2 in the atmosphere from deforestation and burning fossil fuels is creating a global warming catastrophe. But, in the cannabis industry, CO2 extractions use CO2 that is already in the air, so its production process does not cause an increase in greenhouse gas emissions. In fact, closed-loop systems recirculate the CO2.
CO2 is common in various industries, making it a readily available and affordable solvent for cannabis extraction. Compared to other solvents, CO2 is significantly more cost-effective. Closed-loop systems recirculate CO2 through each vessel and recycle it after use. Top-of-the line extraction systems can recover over 95% or more of the solvent used in each extraction run.
Plant Material Extraction Using Supercritical CO2
CO2 extraction is widely used in botanical extraction, including cannabis oil processing. However, extraction processes vary by company. The closed-loop extraction equipment and the standard operating procedures vary by company but all separation processes are capable of isolating essential oils from the plant material in high volumes in a lab setting.
Some cannabis companies start by decarboxylating (heating) and drying their raw cannabis plant material first and then grinding it up to a fine consistency. Then, the ground-up cannabis biomass is loaded into the material column and the essential oil extraction can begin.
At the start of the process, the gaseous carbon dioxide is run through a chamber and is exposed to very low (-70ºF) temperatures and pressures that can convert the gas into a supercritical fluid. In this supercritical state, CO2 can wash over the biomass-filled column. The trichomes from the resinous plant can gently be extracted using supercritical CO2.
Next, the solvent and compound mixture is run through a pressurized separation column. In this column, the temperatures and pressures will vary. The solvent can pull out particular cannabis compounds such as terpenes and cannabinoids from the plant matter.
Finally, the separation column moves the leftover CO2 to a condenser. That is where the CO2 converts back into a gaseous state. In an industrial closed-loop system, the equipment can recycle the gas and keep it for later use.
CO2 Extract Refinement
CO2 extraction can be effective at pulling out tons of plant components. However, it can also pull out some undesirable components like fats, lipids, and waxes.
After the production process, a process called winterization can remove these fats and waxes by using ethanol as a solvent. In the winterization process, the crude CO2 extract is mixed with high-proof alcohol and frozen in the freezer.
Then, the crude extract solution is filtered through a funnel, which separates the undesirable components (fats and lipids) onto filter paper. The CO2 extract solution can be filtered multiple times for greater purity. Afterward, the alcohol must be purged. Processors do so by gently warming the mixture with a rotary evaporating machine.
Since the alcohol and the oil have different boiling points, the alcohol can evaporate first, leaving behind just the pure cannabis oil. In a closed loop system, the alcohol simply gets recycled and reused for later runs.
After the initial refinement process, the CO2-based cannabis oil can undergo further post-processing to isolate and remove certain compounds and undesirable constituents. THC can be separated using short-path distillation.
Short-path distillation, also known as fractional distillation, requires additional labor and specialized techniques. In the distillation process, the cannabis oil is heated at different temperatures to isolate compounds with unique boiling points. The bioactive ingredients are separated as they reach their unique boiling point.
Through this cannabis distillation process, manufacturers can create unique isolates containing a single cannabinoid.
In addition, color remediation technology such as Media Bros’ CR2 uses filtration media such as natural zeolite to create a CO2 extract with better purity, looks, and none of that bitter CO2 taste commonly found in CO2-extracted oils.
What Is Supercritical CO2?
Subcritical CO2 extraction is similar to its supercritical method, but uses lower pressures and temperatures compared to the higher pressures and temperatures of supercritical extraction. While it does not produce a big yield and complete cannabinoid and terpene profile compared to supercritical CO2, producers can retain more of the temperature-sensitive and aromatic terpenes.
Subcritical extraction systems create CO2 extracts with a molasses-like consistency. While the process may degrade much of the cannabinoid content through thermal degradation, it can produce a greater yield of cannabidiol (CBD) in a faster timeframe than other extraction methods.
CO2 Extracts and Infused Products
After the CO2 extraction process has separated the desirable compounds, cannabinoids and terpenes can be crafted into a wide variety of consumable products. In some cases, processors may re-introduce botanical terpenes to CO2 extracts to create a fuller spectrum active ingredients.
For edible production, botanical terpene introduction may not be necessary since people do not normally want the taste of cannabis alongside their foods and beverages. Overall, CO2 extraction can produce pure and potent concentrates for consumers.
Why Extractors Are Going All-in on Carbon Dioxide
Many cannabis extractors are making CO2 extracts due to the high efficiency and relative safety of the production process. Cannabis extraction companies turn to clean and green extraction processes and closed-loop systems that help produce safe and potent concentrates for consumers.
If you are a concentrate producer looking to optimize your CO2 extraction process, Media Bros can turn your high-quality crude into a higher-quality end product. Request a free sample of our CO2 filtration media, send us a message, or give us a call at 971-233-2451 to speak with one of our color remediation experts.