• The CO2 method of extracting CBD can be broken down into three groups of extraction methods: supercritical, subcritical, and mid-critical. The supercritical carbon dioxide method is used to produce a pure CBD product.
  • Under pressure, carbon dioxide (CO2) extracts CBD (and other phytochemicals) from the cannabis plant. At certain temperatures, CO2 functions similarly to a solvent. However, this process is without associated risks.
  • According to research, using organic solvents is the most practical way for medical cannabis extraction(1).
  • Modern techniques, such as those utilized in the UAE (ultrasonic-assisted extraction), SFE (supercritical fluid extraction), and MAE (microwave-assisted extraction), are also considered to be more convenient and time-efficient(2).

What Is CBD CO2 Extraction?

The CO2 method of CBD extraction is separated into supercritical, subcritical, and mid-critical categories. However, supercritical is used for extraction techniques that yield a pure CBD final product.

CO2 cannabis extraction employs carbon dioxide(CO2) under pressure to extract CBD (and other phytochemicals) from the plant. At certain temperatures, CO2 behaves like a solvent yet possesses none of the associated risks. 

Although the process is safe and effective, CBD CO2 extraction requires costly equipment to freeze and compress the CO2 gas into a supercritical cold liquid.

Importance and Benefits of CBD CO2 Extraction

The worldwide market size for industrial hemp was assessed at $4.9 billion in 2019 and is anticipated to reach $18.6 billion by 2027, expanding at a CAGR (compound annual growth rate) of 22.4% from 2021 to 2027(3)

Industrial hemp is a cultivar of the Cannabis sativa plant produced for commercial purposes(4). Industrial hemp is a fast-growing, eco-friendly plant with cheap production costs.

Numerous hemp farmers are finding more accessible solutions for processing and marketing their hemp biomass into their own branded hemp extract, THC-free CBD oil, and cannabis-infused goods.

Hemp growers may transform their newly harvested biomass into branded, shelf-ready CBD extracts, distillates, and hemp oil products, through CO2 extraction.

The main benefits of CO2 extraction are that it eliminates hazardous solvent residues and reduces undesirable chemicals in hemp extracts and CBD products.

More than a thousand chemical compounds are in the cannabis plant, each with unique chemical characteristics that need thorough drying and extraction conditions(5).

For medicinal and dietary uses, it is essential to investigate the extraction and separation of active components and combinations of discovered cannabinoids(6).

Meanwhile, countries worldwide legalize and regulate different varieties of hemp. However, various states in the same nation may have other strict regulatory laws and requirements for the manufacturing and selling of industrial hemp. 

The criteria for hemp containing tetrahydrocannabinol (THC) and cannabidiol (CBD) vary significantly from state to state and nation to country, which complicates commerce. 

​​CBD Extraction Methods

CBD must be extracted appropriately and preserved from the hemp plant before it can be used to produce helpful and highly effective CBD products. It is necessary to maintain the quality and purity of the active component to have a premium CBD product.

There are several techniques for extracting CBD from the hemp plant, including a few do-it-yourself approaches. Here are some of the commonly used extraction techniques:

CO2 Extractions of Cannabidiol

CO2 usually behaves as a gas at normal pressure and temperature. Moreover, it can be readily transformed into a solid in this state. The solid gas form of CO2 is called “dry ice.”

With the use of laboratory equipment, CO2 gas may be converted into a liquid by lowering the temperature to -69 degrees Fahrenheit and raising the pressure to more than 75 pounds per square inch (psi).

At this point, there must be a solid foundation for CO2 cannabis extraction. The following process is necessary:

Supercritical CBD Extraction

Supercritical fluid extraction (SFE) is the large-scale extraction of essential oils and bioactive compounds(7).

In order to execute a supercritical CO2 extraction, certain conditions must be met. The supercritical CO2 extraction systems must be designed to withstand temperatures and pressure.

The extraction vessel contains hemp. For maximum volumetric effectiveness, the hemp biomass must be devoid of moisture and finely ground.

Pressurized CO2 (in the supercritical state) travels through the extraction vessel to interact with hemp, extracting cannabinoids, terpenes, and flavonoids, among other chemicals.

Terpenes are naturally occurring compounds in plants that give them a unique scent. Meanwhile, flavonoids are plant chemicals that possess anti-inflammatory, antiviral, and antioxidant properties(8).

The hemp extract is subsequently transported to collecting vessels using supercritical CO2.

In collecting vessels, the pressures are below the supercritical range, which converts CO2 back into a gas and enables it to be recollected into the CO2 tanks. 

As carbon dioxide transforms into a gas, it loses its solvent characteristics, and the hemp extract separates from CO2.

Various fractions of hemp resin are extracted at varying pressures and temperatures in the collecting containers.

These fractions consist of volatile compounds such as fragrant terpenes and, on the other end of the spectrum, oils and waxes containing cannabinoids such as CBD.

Subcritical CBD Extraction

The sole difference between supercritical and subcritical CO2 extraction is that subcritical CO2 extraction needs less pressure and a lower temperature (a liquid that is not supercritical) than supercritical carbon dioxide extraction. 

These variations in temperature and pressure result in extremely distinct cannabis products. 

The subcritical method preserves and protects the plant’s delicate elements, such as essential oils, terpenes, and other sensitive compounds, which may be desirable for the end product, such as full-spectrum cannabis-based products. 

Supercritical systems generate end products with a peanut butter-like consistency. Higher temperatures and pressures in supercritical systems may extract considerably bigger molecules, such as omega-3 and omega-6 lipids, chlorophyll, and waxes

These molecules are removed using a process known as winterization, leaving only cannabis oil. 

Subcritical CO2 extraction yields a material with a viscosity similar to molasses, which, as stated before, retains cannabinoids other than CBD.

The Olive Oil Extraction Method

Homebrewers who want to produce their own CBD oils may use olive oil extraction

The first step is to decarboxylate or finely crush the hemp. To decarboxylate means to heat the hemp to a specific temperature. 

This process alters the chemical structure of various cannabinoids, making some more powerful and others simpler to extract.

After the first heating, the hemp material is further heated in olive oil to extract the chemicals into the oil. However, this method produces a poor yield and perishable product, making it impractical for large-scale production.

The Dry Ice Extraction Method

Dry ice or ice water extraction produces a powdered resin extract, often known as hash or bubble hash. 

There are several versions of this procedure. However, these are the following basic steps:

  • Manufacturers need to mix finely cut plant clippings with ice or dry ice. The purpose of this process is to separate the extracts from plant material.
  • Manufacturers need to combine the ice and garnishes with water and filter them through a mesh bag. Typically, the mixture is strained many times through mesh bags of decreasing micron size until the cleanest extracts are produced.
  • Manufacturers need to let the extracts sink to the bottom of the strainer’s contents. The excess water is drained off the top of the extracts and dry until they become powder.

Researchers noted that the dry ice procedure effectively condensed THC content to a maximum of 60.7%(9). This process includes the concentration and preservation of monoterpenoids (a class of terpenes) found in new flowers that are often lost during the standard cannabis drying and curing process. 

The Solvent Extraction Method

The solvent extraction method uses liquid solvents, such as alcohol, to extract CBD and other desirable compounds from hemp. 

Alcohol is very effective in dissolving cannabis. Isopropyl alcohol and grain alcohol are the most often used solvents in this CBD extraction method.

This solvent extraction process is quite affordable and does not require costly equipment. Users may already have the necessary materials at home. Solvent extraction may be performed using a hot plate or rice cooker. However, equipment with distillers is more efficient.

Measuring Effectiveness of the Extraction Process

According to research, using organic solvents is the most practical way for medical cannabis extraction(10). However, further study is required for some drying and extraction techniques. In addition, future research should include the development of a green and sustainable cannabis extraction technology.

The same research noted that according to the properties of cannabinoids, slightly polar solvents are generally preferred for extraction(11)

However, for large-scale production, non-polar solvents are also suggested(12)

In general, only certain molecules will dissolve in water initially. The adage “like dissolves like” pertains to the degree to which solutes are soluble or miscible in certain solvents(13)

Almost all compounds are somewhat soluble in all solvents at very low concentrations(14)

Ionic and polar solutes are more soluble in polar solvents. At the same time, non-polar molecules are soluble in non-polar (mainly organic) solvents.

Meanwhile, modern techniques, such as those utilized in the UAE (ultrasonic-assisted extraction), SFE (supercritical fluid extraction), and MAE (microwave-assisted extraction), are also considered to be more convenient and time-efficient(15).

Comparison: CO2 vs. Ethanol Extraction

Ethanol as a solvent may require additional infrastructure investment due to the limits on ethanol storage and requirements for alarm lights, deflagration alarms, detectors, and a complete alarm system for gas detection. 

CO2 does not require any additional expenditures since there is no limit on the amount of CO2 a facility can store on site.

Manufacturers may claim that for quality, ethanol extraction can create high-potency distillate. Ethanol may swiftly remove active components for a high-quality CBD extract. 

On the other hand, CO2 extraction may work for processors who desire full-spectrum extracts substantial in terpenes, cannabinoids, flavonoids, and carotenoids. 

This process helps manufacturers develop a more plant-like CBD product. 

CO2 Extraction Method and the Entourage Effect

Supercritical CO2 enables cultivators and manufacturers to isolate and scientifically study THC and CBD and more elusive cannabinoids such as cannabichromene (CBC) and cannabigerol (CBG). 

Cannabis synergy through the “entourage effect” is now powerful enough to imply that a single molecule is unlikely to match the medicinal or industrial potential of cannabis itself(16).

CO2 extraction may be the key to understanding the hidden medical effects of the other, less abundant cannabinoids and terpenes and how they interact.

However, further clinical studies are needed to prove that CO2 extraction is the best form of extraction to get the entourage effect of cannabinoids and terpenes. 

Pros and Cons of CBD CO2 Extraction

CBD CO2 extraction also has flaws. Even though it is popular and safe, the technique has disadvantages that consumers and CBD company owners should consider. 

CO2 extraction protects CBD products‘ purity. This approach produces potent cannabinoids without chlorophyll and other toxins. Moreover, CBD CO2 extraction may have the purest CBD products

Nevertheless, ​​prices for basic systems for CBD CO2 extraction may still be impractical for manufacturers. The CO2 extraction equipment is costly and requires specialized expertise. Thus, CBD products created through this method are often expensive.

CBD CO2 Extraction Equipment: Why Are Some CBD Oils More Expensive Than Others?

There is no solid clinical evidence as to what extraction process is the best for CBD production. 

The production of pure, effective CBD oil is a lengthy process. Specialized equipment and expensive carrier oils add to the cost.

The extraction process used to extract cannabidiol for CBD oil significantly impacts the oil’s value. Still, CBD CO2 extraction is the most common process utilized by some reputable premium CBD oil manufacturers. 

Extraction using clean, complicated, and environmentally safe procedures is more costly. Small-scale extractors may range from $85,000 to $350,000. Industrial-scale extractors may go up to $500,000 on average. 

Safeness of CBD CO2 Extraction

A clean and cost-effective way to extract cannabinoids from cannabis is through carbon dioxide supercritical fluid extraction (CO2 SFE)(17)

An optimal procedure for extracting medical cannabis bud material (mixed plants, THC: CBD around 1:1.5) was established by using the design of the experiment method. 

The first eleven batches showed that the CO2 flow rate affects the overall yield and recovery of the key cannabinoids, especially CBD(18).

This approach yielded the highest THC and CBD recoveries(19). It is the first research to describe the repeated extraction of 15 kg of cannabis to optimize a pharmaceutical product’s CO2 SFE extraction procedure.

Deciding if CBD Products Created by CO2 Extraction Are Right for CBD Users 

Consumers may have discretion on whether CBD CO2 extraction is right for them. The price may be relatively higher in the CBD market. 

However, users may choose CBD CO2 extraction for its benefits over other forms of CBD extraction. The extraction process can preserve a greater concentration of cannabinoids and other beneficial CBD compounds. Still, consumers should be cautious when purchasing CBD from different sources to get high-quality CBD products. 

  1. Processing and extraction methods of medicinal cannabis: a narrative review
  2. Ibid.
  3. Industrial Hemp Market by Type (Hemp Seed, Hemp Oil, Hemp Fiber and Others), Application (Food and Beverages, Textiles, Personal Care Products, Pharmaceuticals and Others) and By Source (Conventional and Organic): Global Opportunity Analysis and Industry Forecast, 2021–2027
  4. Ibid.
  5. Processing and extraction methods of medicinal cannabis: a narrative review
  6. Ibid.
  7. Supercritical fluid extraction of cannabinoids (THC and CBD) from four different strains of cannabis grown in different regions
  8. Flavonoids as antioxidants
  9.  Novel Solventless Extraction Technique to Preserve Cannabinoid and Terpenoid Profiles of Fresh Cannabis Inflorescence
  10. Processing and extraction methods of medicinal cannabis: a narrative review
  11. Ibid.
  12. Ibid.
  13. Processing and extraction methods of medicinal cannabis: a narrative review
  14. Ibid.
  15. Ibid.
  16. What is the Cost of a Supercritical CO2 Extractor?: Factors, Considerations and Specifications
  17. Utilisation of Design of Experiments Approach to Optimise Supercritical Fluid Extraction of Medicinal Cannabis
  18. Ibid.
  19. Ibid.
CBD Clinicals is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Learn more