In a super-cryo ethanol extraction process such as ours, the initial step is to introduce ethanol to a large centrifuge with the hemp biomass at very low temperatures. The hemp/ethanol mixture is spun and agitated to allow the ethanol to dissolve the desired cannabinoids from the hemp material. After this initial step, the operation following involves purifying and isolating the desired products from the hemp material and removing any unwanted impurities.
A falling film evaporator is a specific type of vertically-oriented shell and tube heat exchanger that is used to separate two or more substances with different boiling point temperatures by dividing the material into thin films. Heat is transferred rapidly and efficiently across a shell and tube heat exchanger between the media and CBD/ethanol mixture. Under pressure, the contents are spread evenly in a thin film from the top to the bottom for even heat distribution. In doing so, the thin layers can be heated more easily to efficiently evaporate ethanol from the mixture. As the ethanol evaporates into a vapor-liquid form, it is separated by entering a condenser to cool back to a liquid form. The ethanol is then recycled back into storage for future use.
Different distillation processes are applied for a partial separation of product mixtures. The most important requirement for all distillation processes is the boiling point difference of the fractions that need to be separated. Wiped film distillation is a thermal separation process for thermally sensitive products. Short residence time and low evaporation temperature will cause minimal thermal stress to the distilled product and results in a gentle distillation. This allows for the cannabinoids to remain intact and not degrade during the distillation process.
We use wiped film distillation to separate CBD from other compounds in the crude oil by taking advantage of differences in boiling points of compounds within the crude. In wiped film distillation, the crude material is heated up on the internal surface of a heated tube. A special rotating wiping system with paddles inside the evaporator smears the crude oil to increase surface area, generating a very thin and turbulent film on the heated surface. Within the distillation column, the evaporation of the components with lower boiling points takes place. We collect the CBD condensate and the terpenes in different condensers and the remaining material are the compounds with high boiling points that never evaporated.
After purifying the distillate, the oil undergoes a process called recrystallization. In chemistry, recrystallization is a technique used to purify chemicals. The desired compound can be isolated and impurities can be removed from the solution. To perform recrystallization, a solvent (a chemical able to dissolve other substances) is added to a mixture, in our case CBD distillate, and heated until all of the distillate dissolves in solution. After the CBD distillate dissolves the temperature of the mixture is lowered significantly, this is sometimes referred to as “crashing”. As the mixture is allowed to cool, the CBD molecules within the mixture reassemble into a crystalline structure, separating themselves from the rest of the mixture. This manipulation of temperature called recrystallization is a well-known and used technique in the organic chemistry laboratory. Isolate is tested using advanced chemistry instrumentation to determine and certify the composition is purely CBD with non-detectable (ND) amounts of other cannabinoids, such as THC. Thus, there is no THC in isolate CBD extracts or finished products.
Flash chromatography is an analytical chemical separation technique used in chemical laboratories to purify mixtures. Although our hemp derived products are distilled using falling film and wiped film distillation, some terpenes, cannabinoids and solvents remain and must be remediated using analytical instrumentation.
Flash chromatography is performed by introducing a mixture into the instrument with the aid of a solvent. Compounds in solution will, based on their particular chemistry, separate from each other due to their polarity differences, given the right conditions and technique. The mixture is added to the top of the column, solvent is introduced into the column using a pump. In reverse-phase chromatography, the solvent mixture is introduced into a column lined with a highly polar substance lining the inside of a column. The more polar a component of the mixture, the slower it will pass through the column due to polar compounds being attracted to other polar compounds lining the column. Conversely, less polar compounds will pass through the column more quickly. The rate at which compounds pass through the column is referred to as retention time. Although the instrumentation is highly advanced and complex, the principle in which it functions is as simple – separate components based on their respective polarities. The collected materials following this process will be purer than when they were in the original mixture.
This process allows us to remediate remaining tetrahydrocannabinol (THC), terpenes or other undesired components of the final product. Additionally, flash chromatography is used every step of the way during the extraction process to ensure intermediate products are being extracted efficiently to determine if parameters need adjustment during the distillation phase.
High performance liquid chromatography (HPLC) is another analytical chemical separation technique that takes advantage of the varying polarity of components within a mixture. However, HPLC differs in that the column is much smaller in comparison to flash chromatography and is under high pressure. The smaller column under pressure creates more specific parameters allowing for greater scrutinization in the removal of undesired compounds within the final product. Similar to flash chromatography, components of a mixture can be separated based on their respective polarities. For instance, if a sample contains both THC and CBD, the mixture is introduced into the instrument with the assistance of a solvent under high pressure to move the mixture through the column. Using reverse-phase chromatography, the polar lining of the column is attracted to the more polar compounds in the mixture. CBD differs from THC only in the number of -OH functional groups, CBD has two while THC contains only one. Thus, the CBD will pass through the column more quickly and arrive at the detector before THC, allowing our team to separate these two components to produce isolate or a broad spectrum distillate with non-detectable traces of THC.