Cannabidiol (CBD) derived from hemp has seen a tremendous increase in public acceptance over the last few years. The FDA’s authorization of Epidiolex and the non-intoxicating nature of CBD have spurred a surge in cultivation, production, and demand for this product.
CBD is one of the popular cannabinoids that hemp and cannabis plants produce. Because of THC contamination limits, one of the most important processes in production is the isolation through reactors to achive pure forms of CBD. Recrystallization using Crystallization Reactors is a typical method for isolating pure CBD from less pure combinations.
Crystallization Reactor
The most crucial piece of cannabis crystallization equipment is the crystallization reactor. These crystallization tanks are built, engineered, and inspected according to the ASME Boiler and Pressure Vessel Code. A crystallizing reactor tank is a crystallizing tool in which chilled glycol water rapidly cools the jacket. The kind of jacket, the structure of the agitator, and the shape of the exit are all essential considerations.
The Crystallization Reactor is used to produce very high-quality CBD on a big scale without complicated equipment. Dissolve the clear CBD oil that has already been winterized and distilled to cool gently in near-boiling heptane or pentane to get crystalline CBD.
CBD Crystallization
Crystallization is the process of isolating a solute from a solvent by forcing it to solidify. This is accomplished by operating the solute’s solubility in the solvent. Temperature manipulation is the typical method for accomplishing this. This is known as chilling crystallization, and it is used to separate CBD isolate from CBD distillate.
To execute a cooling crystallization, the solute must be sufficiently soluble in the solvent at the beginning (higher temp) temperature and insoluble in the solvent at the end (lower temp). The more insoluble the solute is at lower temperatures, the better because this enhances theoretical yields over a practical temperature shift by forcing more of the solute out of the solution.
The technique is the same in the case of CBD isolate. CBD from CBD distillate is diluted with a hydrocarbon solvent (usually pentane or heptane) and then cooled, causing the CBD molecules to crystallize into CBD isolate crystals.
Pure Quality CBD Distillate
Extracted CBD oil that has been winterized and distilled should be used as the starting material. CBD distillate should be very clear. Cloudiness indicates the presence of impurities such as water, waxes, and lipids. If the oil is foggy, repeat the winterizing process until the oil is clear. Crystallizing oil contaminated with contaminants will result in low yields.
Crystallization Process
Crystallization Equipment
A jacketed jar with stirring will be needed to dissolve and crystallize the CBD. A heating/cooling bath is linked to the vessel jacket and will be used to regulate the vessel’s temperature.
Dissolving CBD
Pentane should be used to dissolve the transparent CBD oil. Ensure that the jacketed vessel’s vent is linked to a suitable blower motor or fume hood for pentane vapors. Pentane has a boiling point of 36°C. Pentane emits a large amount of vapor even at lower temperatures. Ensure that the vessel condenser is cooled to -20°C. In the jacketed vessel, combine 1 part pentane and 2 parts CBD oil (certain oils require more or less pentane). Turn on the stirring and the heating bath, and set the temperature to 45°C. Wait until the solution reaches 45°C, and the oil has completely dissolved.
Precipitation
Set the bath temperature to 5°C. Slow down the stirring. The solution will get denser as it cools. RPM should be kept above 120 by adjusting the stirrer. CBD crystals will form or “crash out” of the pentane solution on their own. Continue to lower the temperature to at least -10 C. The temperatures you utilize and how they change over time can influence crystal formation.
Collect CBD Crystals
After the precipitation has stopped, flush or physically remove the CBD crystals from the reactor. To separate the mother liquor from the CBD crystals, vacuum filter the crystal (liquid slurry). To remove contaminants from the crystal surfaces, rinse them with ice-cold pentane. More pentane rinses can improve bad color, but the total yield will suffer. Keeping the CBD and materials cool during this step will assist in yield.
Improve CBD Purity
CBD distillate with a CBD content of 70 – 75 percent can be crystallized to generate CBD isolate (crystals) with a purity of 90 percent or higher. CBD distillate with less than 70% CBD can be crystallized to generate an 85 percent purity or greater CBD isolate. CDB crystals can be re-dissolved and recrystallized to increase potency even further.
