In the cannabis industry, a lot of the innovation is focused on making products purer and more potent while maintaining their natural profile. That’s why several extraction methods are used. Among these techniques, supercritical CO2 extraction has emerged as one of the leading methods as it maintains the highest quality and efficacy of cannabis oils. This process is based on using carbon dioxide to extract compounds from the cannabis plant at a supercritical temperature and pressure.
As a producer, the supercritical CO2 extraction method can help improve the quality and yield of your final products. This guide provides a detailed overview of supercritical CO2 extraction, explaining the science behind this method. We also explore its practical applications and impact on the cannabis industry.
Abbreviated as ScCO2, Supercritical CO2 is the term used to refer to carbon dioxide gas that has been pressurized and heated to a point where it exhibits properties of both a liquid and a gas simultaneously. This unique property of CO2 allows it to act as a highly efficient solvent for extracting compounds from plant material. To achieve the supercritical state, CO2 is heated above 31.1°C (87.98°F) and pressurized above 73.8 bar (1,071 psi). Supercritical CO2 is highly efficient in extracting cannabinoids and terpenes from cannabis plants.
The Science Behind Supercritical CO2 Extraction
To put carbon dioxide in its supercritical state where it acts as both liquid and gas, its critical point (31.1°C and 73.8 bar) is exceeded using specialized equipment. In this state, supercritical CO2 exhibits properties that make it ideal for extraction. These properties include:
- The high density, which is similar to liquids, allows for the efficient dissolution of compounds
- With increased solubility, supercritical CO2 can dissolve a wide range of organic compounds
- The low viscosity of supercritical CO2 enables easy flow through plant material
- It has high diffusivity penetrating deep into plant matter
- Negligible surface tension allows for easy penetration of tiny pores
- Supercritical CO2 has high compressibility, implying its density can be easily manipulated for selective extraction
- Higher thermal conductivity at this state enables efficient heat transfer during the process
- The non-toxic nature of CO2 makes it safe for both operators and consumers
All these properties make supercritical CO2 a highly efficient solvent for extracting compounds from cannabis. As the CO2 flows through the plant matter, it acts as a solvent, dissolving and carrying away desired compounds such as cannabinoids and terpenes. Due to easy manageability, the solvent properties of supercritical CO2 can be fine-tuned by adjusting temperature and pressure. It makes selective extraction of specific compounds possible.
The science behind supercritical CO2 extraction is rooted in thermodynamics and fluid dynamics. By manipulating the temperature and pressure, operators can easily alter the density and solvating power of the CO2. It allows CO2 to penetrate plant material more effectively than liquid solvents. Furthermore, its gas-like viscosity and diffusivity enable it to reach deep into the plant structure. Combining both states results in a more efficient extraction process than traditional methods.
Supercritical CO2 Extraction Process
The supercritical CO2 extraction process is a sophisticated method with several vital stages. You should know each stage if you consider adopting this extraction process to improve your product’s quality.
1. Preparation:
The first stage involves preparing the raw materials and CO2 for extraction.
- Preprocessing of cannabis: The plant material is dried and ground to increase surface area and improve extraction efficiency. Proper drying and grounding are necessary to ensure the quality and overall yield of the extract.
- CO2 preparation: CO2 must be of high-purity. It requires specialized tanks to store CO2 and prepare it for use in the extraction system. The purity of the CO2 is essential to ensure a clean, contaminant-free extract.
2. Extraction Phase:
- Loading the extraction vessel: Well-dried and grounded cannabis raw material is loaded into the extraction chamber of the supercritical CO2 extraction machine. The raw material is tightly packed as the density and uniformity are essential factors influencing extraction efficiency.
- Setting extraction parameters: Pressure and temperature of CO2 are carefully controlled to achieve the desired supercritical state. The exact parameters maintained depend on the specific cannabinoid or terpene profile being targeted.
- Flow of CO2: Supercritical CO2 is pumped into the extraction chamber to penetrate the plant material, dissolving and carrying away target compounds. The flow rate must be maintained as it also affects the extraction efficiency and selectivity.
3. Post-Extraction:
- Separation: The CO2-extract mixture is depressurized in the separation chamber once the compounds are dissolved. It causes CO2 to return to a gaseous state and separate from the extracted cannabis oil.
- Collection: Post CO2 separation, the extracted oil is collected in a separate chamber while the CO2 is recycled back into the system. This recycling capability is one of the eco-friendly aspects of supercritical CO2 extraction.
4. Purification:
- While the supercritical CO2 extraction process results in highly pure cannabis oil, it still can contain unwanted lipids and waxes. Additional steps, such as winterization and distillation, may be employed to remove contaminants. Winterization involves dissolving the extract in ethanol and freezing it to precipitate out the waxes. Distillation is another purification method to refine the extract further and isolate specific compounds.
- Any residual CO2 is wholly removed, ensuring a pure, solvent-free final product. This is typically achieved through time, heat, and vacuum processing.
Supercritical CO2 Extraction vs. Subcritical Extraction
CO2 is used at a subcritical state for the extraction process as well. Thus it is useful to understand the differences between supercritical CO2 extraction and subcritical extraction.
Efficiency and Yield:
- Supercritical CO2 extraction of cannabis generally offers higher efficiency and yields. CO2 has the highest solvating power in a supercritical state, making it ideal for high-throughput commercial extraction operations.
- Subcritical extraction may have lower efficiency yields but is gentler due to lower heat and pressure. It makes subcritical CO2 extraction suitable for heat-sensitive compound extraction, such as delicate terpenes or other volatile compounds.
Quality and Potency:
- Supercritical CO2 extracts have higher potency due to more purity and thorough extraction of cannabinoids. This makes the process particularly beneficial for producing high-concentration products like vape oils or dabs.
- Subcritical extraction preserves certain terpenes and other volatile compounds, resulting in extracts with more complex flavor and aroma profiles. It is a preferable extraction method for producing products required for their therapeutic properties.
Applications in Various Products:
Due to the high concentration of the compounds, supercritical CO2 extraction process is used for producing products such as:
- Vape Cartridges that have High potency (70-90% THC) and minimal residual terpenes.
- Concentrates such as wax crumble and shatter with high cannabinoid content (80-90%).
- Full-spectrum, high-potency tinctures.
- Capsules and pills for precise dosing of concentrated cannabinoids.
- High-potency creams and balms.
- Isolates such as pure CBD, THC, or other cannabinoid crystals (99%+ purity).
Subcritical CO2 extraction also produces the same variety of products but with different concentrations of terpenes. It includes:
- Full-spectrum tinctures that are rich in terpenes and minor cannabinoids.
- Aromatherapy products such as terpene-rich essential oil blends.
- Flavoring agents for food and beverage applications.
- Live resin products are famous in high-end vape cartridges and concentrates.
- Topicals such as whole-plant extracts for balms and salves.
- Edible ingredients that are often used in gourmet or artisanal cannabis edibles.
- Skincare products that require minor cannabinoids and terpene extracts, such as anti-aging creams, serums, and lotions.
Many producers combine both methods or adjust parameters within the supercritical range to produce desired products. The hybrid approach results in a high-potency extract that retains the full spectrum of the plant’s compounds. Irrespective of the method used, the products produced are highly sustainable.
Equipment and Technologies Used for Supercritical CO2 Extraction
The supercritical CO2 extraction equipment consists of several essential components. As it is a significant investment decision, producers should understand the type of equipment, key elements, and technology available.
Types of Equipment:
- Extraction vessels: These are the high-pressure chambers, generally made from stainless steel, where the cannabis material is placed. These heavy-duty vessels are designed to withstand the high pressures of supercritical CO2 extraction.
- CO2 pumps: These are high-pressure pumps to circulate CO2 through the system. These pumps are designed to achieve and maintain the pressures required for supercritical conditions.
- Separation vessels: These stainless steel chambers separate the extract from CO2. These vessels are designed to facilitate the rapid phase transition of CO2 from supercritical to gaseous state.
Key Components
- Heating elements: The purpose of these components is to maintain CO2 at supercritical temperature (above 31.1°C). Supercritical CO2 extraction equipment can include heating elements such as electric resistance heaters, heat exchangers (larger systems), and thermoelectric coolers (for precise temperature control). Such systems have PID (Proportional-Integral-Derivative) controllers and computerized temperature management to better control the temperature.
- Pressure regulators: These components maintain CO2 at supercritical pressure (above 73.8 bar). This is achieved using back pressure regulators, dome-loaded pressure regulators, and electronic pressure controllers. Pressure regulators can have mechanical spring-loaded designs or electronically controlled regulators, depending on your chosen equipment.
- CO2 recovery systems: Recovery systems are used to recapture and reuse CO2 after extraction and reduce operational costs and environmental impact. Condensers (to liquefy CO2 gas), storage tanks (for recaptured CO2), and purification systems (filters, molecular sieves) are part of the CO2 recovery systems.
With the evolution of technology, innovations are taking place in supercritical CO2 extraction machines for better efficiency and control. Innovations are being made for more precise temperature and pressure control systems, improved flow dynamics, and enhanced separation technologies. A modern supercritical CO2 extractor has automation and digital control systems, allowing precise parameter management and consistent results. Additional features like touch screen interfaces and data logging capabilities help in process optimization and quality control.
Cost Analysis of Supercritical CO2 Extraction
The initial setup cost for supercritical CO2 extraction equipment can range from $100,000 to over $1 million, depending on scale and features. A small-scale system producing 10 to 80 pounds daily can range from $85,000 to roughly $300,000. At the same time, an industrial extractor can produce over 850 pounds a day and cost over $500,000. However, the initial setup cost can be significantly higher as it includes facility modifications such as reinforcing floors and installing proper ventilation systems.
Maintenance and repairs for complex supercritical CO2 extraction machines entail ongoing operational costs. To ensure efficiency and safety, regular maintenance is crucial. Ongoing costs can include expenses for replacement parts, technician visits, and potential downtime. CO2 supply and utilities (electricity, water) for continuous operation are also part of ongoing operation costs.
Other factors that can influence the cost of supercritical CO2 extraction include scale of operation efficiency and throughput. In contrast, the larger systems offer economies of scale but require higher initial investment. More efficient systems, such as those provided by Root Sciences, may have higher upfront costs but lower long-term operational expenses.
When considering the cost of setting up supercritical CO2 extraction equipment, it is essential to factor in long-term operational costs and potential returns, not just immediate expenses.
Benefits of Using Supercritical CO2 Extraction
The supercritical CO2 extraction process offers several benefits over other methods of extraction. This method is preferred because of its:
Safety Aspects:
- CO2 is non-toxic and non-flammable, even in a supercritical state. It makes it highly safe and reduces the risks associated with other solvents. CO2 is safe for operators and the surrounding environment, reducing the need for extensive safety measures for flammable solvents.
- CO2 is safer to store compared to volatile organic solvents. No special equipment or safety measures are required as CO2 is inert at room temperature and pressure.
Environmental Impact:
- As CO2 is recycled and reused in the extraction process, there is no wastage of the solvent. Also, the closed-loop system minimizes the environmental footprint of the extraction process.
- While supercritical CO2 extraction does require energy for pressurization and temperature control, it is more energy efficient. Due to the purity of the end products, they don’t have extensive post-processing or solvent recovery like other traditional methods.
Quality of the Final Product:
- Supercritical CO2 extracts are known for their high purity and potency. The selectivity of the process allows for the extraction of desired compounds up to 95% pure.
- The extraction process can preserve a wide range of cannabinoids and terpenes. This makes it possible to obtain full-spectrum extracts.
Potential Challenges and Limitations
Supercritical CO2 extraction has potential challenges. For producers, it is essential to be aware of the challenges and limitations.
Technical Challenges:
- Supercritical CO2 extraction requires maintaining high pressure and temperature. The equipment used is complex and requires specialized knowledge to operate effectively. Producers must ensure extensive training for operators or hire experienced personnel.
- Regular equipment and facility maintenance is crucial to ensure consistent performance and avoid costly downtime. The high-pressure nature of the pressure means frequent wear and tear and requires replacement.
Extraction Yield or Quality:
- The supercritical CO2 extraction method may not be ideal for some cannabis strains or materials. For instance, strains with high wax content may not result in lower yields.
- Fine-tuning of pressure and temperature is necessary to avoid the degradation of sensitive compounds. This can require extensive experimentation for optimal results with different strains or desired end products.
Regulatory Considerations:
- Compliance with local regulations regarding cannabis extraction and processing can vary by jurisdiction. You may have to obtain equipment certification and product testing reports.
Future Trends and Developments in CO2 Extraction
Emerging technologies
Continuous improvement in supercritical CO2 extraction machine design results in increased efficiency and ease of use. This includes advancements in automation, process control, and user interfaces. For example, Root Sciences CDMH.5-2x-2f CO2 extraction equipment is a fully automated control system. It allows 100% communication with Ancillary Equipment, resulting in a more efficient process. Integration of supercritical CO2 extraction with other techniques like ultrasound-assisted extraction for enhanced results is another innovation being experimented with.
Trending in the cannabis industry
As the demand for high-quality, solvent-free extracts grows, producers increasingly adopt supercritical CO2 extraction. This is a beneficial method in medical cannabis markets where purity and consistency are paramount. With ongoing research into cannabinoids and terpenes, the potential applications of CO2 extraction are widening. As this extraction method preserves a broad spectrum of compounds, it can be used for several applications.
Potential Advancements
Developing more cost-effective supercritical CO2 extraction equipment has made the technology accessible to smaller producers. Also, the process is becoming more accessible to manage, which could lead to greater diversity in the cannabis extract market. Furthermore, the application of supercritical CO2 extraction is beyond the traditional cannabis industry and extends to pharmaceuticals, nutraceuticals, and other industries.
Conclusion
Supercritical CO2 extraction is increasingly adopted in the cannabis oil industry. It offers a safe, efficient, and versatile method for producing high-quality cannabis extracts. The ability to produce pure, potent, and consistent cannabis extracts using supercritical CO2 has opened up new possibilities for product development and therapeutic applications. Producers can use this versatile method to produce a full range of products, from full-spectrum oils to isolated cannabinoids.
The process’s safety, efficiency, and extract quality make supercritical CO2 extraction highly profitable. While the initial costs may be significant, the long-term benefits of product quality, safety, and versatility can provide a substantial return on investment.
