FAQ Extraction

Extraction

• Does the presence of water in the material influence the extraction process?

• If the material to be extracted contains any water, it will have a negative effect on the extraction process, as the extract will then also contain water, which has to be removed with additional processing steps. In order to avoid this problem, it is recommended that the material be dried before extraction.

• Can CBD be obtained with supercritical CO₂ extraction?

• CBD (Cannabidiol) is just one of the components of the full spectrum oil product that can be extracted from the matured flowers of the Cannabis sativa plant. In addition to CBD, which is the major nonpsychotropic constituent represented in the highest concentrations, the extracted full spectrum product also contains a mix of natural components such as other cannabinoids (CBN, CBC, CBG …), terpenes, and other molecules. All these components incite a broad range of effects on the receptors of the ECS endocannabinoid system in the organism.

• What type of solvent is CO₂, polar or nonpolar?

• CO₂ is nonpolar, therefore it is the best tunable solvent for the extraction of oils and fats. Due to its nonpolarity, it is a very effective solvent for lipophilic substances such as triglycerides (vegetable oils and butters), essential oils, and lipophilic vitamins. On the other hand, water is very polar and deemed as the most “universal” solvent in nature.

  Solubility is usually explained with the saying "Like dissolves like", which means that nonpolar reactants will dissolve in nonpolar solvents and polar reactants will dissolve in polar solvents. Intermediate solvents such as ethanol, methanol, and acetone are used for tuning the solubility power. The dielectric constant of a solvent is a measure of its polarity (symbol: ε). The higher the dielectric constant of a solvent, the more polar it is. By adjusting the pressure and temperature set point, we can simulate the density and solubility power of different organic solvents, ranging from chloroform to methylene chloride to hexane.

• How does the extraction process with supercritical CO₂ work?

• Extraction with supercritical fluids is a multistage separation process where one or multiple components are separated from the matrix using a supercritical fluid as the extracting solvent. In the initial phase, liquid CO₂ is pumped through a heat exchanger and into an extraction vessel using a high-pressure pump. In the heat exchanger, the CO₂ enters the supercritical state under a controlled set pressure and temperature. The supercritical CO₂ then passes through the extraction vessel which has been pre-filled with dried and crushed plant material. During the extraction, the supercritical solvent passes through the plant material and dissolves the soluble compounds. The pressure in the extraction vessel is maintained using a PLC-controlled pressure regulator. A mixture of solute and supercritical fluid is transferred to the collection vessels where the pressure is gradually relieved. By lowering the pressure, the dissolution power of CO₂ gradually decreases and the dissolved compounds (fractions) are consequently separated from the solvent. Finally, the pressure in the system is reduced, the CO₂ returns to its gaseous state and has no power to dissolve. It is then cooled again and liquefied in a gas recycling system from where it returns back to the process.

• How do I know if my Supercritical CO₂ Extraction system investment idea is feasible?

• An economic evaluation based on a detailed profitability analysis showed that SFE is an economically feasible process, as it disclosed the encouraging values of return on investment (ROI) and net present values (NPV) for all scale-up capacities. Hence, the kinetic study for the SFE process by using mathematical modelling on overall extraction curve (OEC) of laboratory-scale data is crucial. However, many cases on increasing the scale from laboratory to the industrial level showed a significant decrease in extraction yield. Hence, an intermediate-scale experiment (pilot scale) was a better strategy because it considered the restriction that might occur on the industrial-scale. This way, the laboratory-scale data could be safely utilized to develop the economic evaluation for the SFE process, in which the process tendency is to sustain the extraction yield with increasing scale. According to Pereira et al., the most reported drawback of SFE for the past 20 years was a high initial investment cost on industrial plants. SFE was considered too expensive by many investors because of the high investment costs compared to conventional low-pressure equipment. Therefore, the use of this technology for high-added-value products was restricted. However, if considering the use and quality of its product, the operating costs of SFE were relatively low.

• How is the extraction process carried out?

• In order to ensure the best yield of extraction, it is imperative to carry out several sample/material preparation steps of pre- and post-extraction techniques that can help improve the extraction yield and refine the final product. After CO₂ is pressurized to a supercritical state, supercritical CO₂ is passed into the extraction vessel containing the loaded and shredded plant material. The supercritical CO₂ acts as a solvent diffusing into the plant matrix and dissolving the target compounds. The solubility of different compounds in supercritical CO₂ varies based on factors such as pressure, temperature, and the chemical properties of the compound. Selective extraction can be achieved by adjusting the pressure and temperature. Lowering the pressure leads to the extraction of volatile compounds while raising the pressure can improve the extraction of less volatile compounds.

  A higher temperature boosts the extraction of less volatile compounds and improves the solubility of certain compounds but it has to be controlled in order to avoid thermal degradation.

  The hemp post-extraction process usually consists of four steps: winterization, filtration, evaporation, and further refinement, such as chromatography.

  https://sk-skrlj.com/en/extraction.

• How efficient is the extraction process?

• We usually measure and express the efficiency of the extraction method with yield. The yield of any extraction process depends upon the quality of the original source material (matrix). For example, different cannabis strains show different cannabinoid profiles and produce specific levels of CBD.

• What are the advantages of SFE compared to traditional extraction methods with organic solvents?

• The extraction process with supercritical CO₂ is very fast compared to traditional methods and very economical to operate/run. There is only a small amount of organic solvent used for the cosolvent extraction or in most cases none at all, which results in practically no solvent residue. This method is known for perfectly preserving thermally labile compounds. CO₂ as a solvent is easily tunable and can be used very efficiently for a broad range of selective extraction tasks. Due to its great selectivity, the targeted compounds can be extracted out of complex matrices. It is possible to conduct a selective extraction by tuning the pressure and temperature in a way that preserves the volatiles and the thermolabile molecules. Additionally, the closed-loop system used in supercritical CO₂ extraction minimizes the release of CO₂ into the atmosphere.

• What process parameters are controlled during the extraction process?

• The extraction process is controlled using an integrated PLC system where the parameter settings are presented graphically on the touch screen. The process parameters such as temperature, pressure, flow, extraction time, and S/S ratio are set and stored as a method (recipe) that enables reproducible operation.

• Under what conditions will CO₂ reach the supercritical stage?

• Carbon dioxide (CO₂) enters the supercritical fluid state at its critical temperature of 31.1 °C and relatively low critical pressure of 72.8 bar.

• How much CO₂ is used and how much of it is lost during the extraction process?

• In modern extraction systems, equipped with a recycling vessel, CO₂ recirculation is continuous. In theory, this process can run indefinitely.

• What is the main advantage of supercritical CO₂ as a “green” solvent?

• CO₂ is an inexpensive and readily available so-called GRAS (generally regarded as safe) solvent that is very easy to recycle and reuse. By using CO₂, we can avoid the use of other solvents and as a consequence the need for solvent waste that require special environmentally hazardous and costly waste treatments like special incineration facilities.

  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6152233/