Dissolve the clear CBD oil in pentane. Make sure the jacketed vessel’s vent/condenser is connected to an appropriate blower motor or fume hood for pentane vapors. The boiling point of pentane is 36 °C. Even at lower temperatures, pentane will release many vapors. BE CAREFUL AND TAKE ALL PROPER PRECAUTIONS! Make sure the vessel condenser is cooled to -20 °C. Add 1 part pentane to 2 parts CBD oil (some oils require slightly more or less pentane) in the jacketed vessel. Turn on stirring and turn on the heating bath and set to 45 °C. Wait until the solution reaches 45 °C and all the oil has dissolved.
ACS grade pentane will be the solvent. This can be dangerous stuff. Consult your safety officer!
A jacketed vessel with stirring will be used to dissolve and crystallize the CBD. A heating/cooling bath is connected to the vessel jacket and will be used to control the temperature of the vessel.
CBD distillate with 70 – 75% CBD content can be crystallized to produce CBD isolate (crystals) with a 90+% purity or higher.
B/R Instrument’s 20 Liter stainless steel jacketed reactor. Perfect for CBD/CBG isolation.
Once precipitation stops, flush or physically remove The CBD crystals from the reactor. Vacuum filter the crystal/liquid slurry to remove the mother liquor from the CBD crystals. Rinse the crystals with ice-cold pentane to rinse impurities from the crystal surfaces. More rinses with pentane can improve poor color, but losses in total yield will occur. Keeping the CBD and materials cold during this step will help give you a better yield.
Fig 3: ‘Crash cooling’ crystallization
In the case of CBD, this can mean THC, pesticides, solvent and other cannabinoids becoming entrapped in the CBD crystals, requiring resource-intensive recrystallization operations to achieve the required purity.
There are several steps required to take the cannabis biomass ‘from crop to crystal’. These steps will vary depending on the user’s preferred extraction method, but typically the steps are as follows:
Can you perform seeded, cooling crystallization in batch stirred tanks?
The enhanced control of crystallization pathway in a NiTech ® continuous crystallizer results in a high CBD isolate yield (close to the theoretical maximum) and a high-purity product with a uniform crystal size for simpler downstream processing.
Precipitation is rapid and forms a large quantity of small particles, as rate of formation of new solids greatly exceeds the rate of crystal growth. Also, due to the speed of precipitation, other components become entrapped in the precipitate, resulting in a lower purity material; these can include the solvent as well as other components present in the solvent system at the time.
CBD isolate is often produced using crash cooling (this is precipitation). As demonstrated in Fig 3:
If you also require assistance with step 6, the filtration, washing and drying of CBD isolate, we recommend our friends at Alconbury Weston Ltd (AWL)