Thursday, August 1, 2019
Industrial hemp production is growing rapidly across the globe due to the explosive growth in CBD products on the market. A variety of methods are used for extracting THC, CBD, Cannabinoids, and Terpenes from hemp and cannabis plants. The most common extraction methods used in extraction facilities today are:
As the CBD market expands, farmers are growing more and more acres and increasingly larger volumes of hemp. Large scale CO2 and Ethanol extraction are emerging as the leading methods for processing these very high volumes of plant material.
Ethanol is a logical favorite for hemp extraction into CBD oil.
Naturally, there are pros and cons to every method, and ethanol extraction does come with its downfalls—but the industry is working fast to address those drawbacks. Ethanol readily breaks down and dissolves chlorophyll, the green pigment in plants that absorbs light to provide energy for photosynthesis. Unfortunately, chlorophyll is ‘undesirable’ in a finished extraction, and ethanol can make it difficult to pull the grassy-tasting chlorophyll from the end product.
Post-process equipment, including filtration and distillation, can be used to remove the chlorophyll to ‘clean up’ the oil into a more desirable distillate. Additionally, after extraction, all the ethanol is reclaimed and saved for reuse in the next extraction. By using rotovap (rotary evaporator) technology or high-volume solvent recovery systems, reclaiming ethanol is simple, efficient and safe because the systems will always run well below ethanol’s flash point.
With ethanol extraction systems, we can customize to the exact weight or volume you want to process, allowing you to run anything from small 1 pound batches to very large extractions of 500 lb or more. These sanitary ethanol reactors come built with a 316 liter stainless steel recirculation system, plant material holders, and can have chilling jackets for dry ice or nitrogen super cold chilling. Scaling up and down is consistent and repeatable other than variations in the incoming plant material.
Pure ethanol is food grade, GRAS, and readily available. Extractions using ethanol can be done in simple stainless steel tanks or more complex tank systems. This equipment is fairly inexpensive and simple compared to C02 and Butane extraction equipment. CO2 and Butane systems are also limited to the amount they can process at one time by the size of the extractor column, and they both have a lengthy process time in comparison to ethanol. Using ethanol as a solvent allows for much larger extraction batches in a shorter amount of time, and if done properly, it will avoid extracting undesirable material from the biomass making downstream processing easier. Ethanol is flammable and should be handled with care, and any rooms should be properly vented and all tankage/piping should be grounded per code. Ethanol extraction is the method of choice for so many of today’s high-quality botanical extractions, and it is gaining traction as one of the most effective solvents on the market today.
Chilling the ethanol and plant at -40f range will provide a much cleaner extraction, by preventing the extraction of chlorophyll, wax and lipids from the plant, and targeting the cannabinoids. Tanks can be chilled by dry ice, jacketed double-wall tanks with chilled ethylene glycol, or with super-chilled nitrogen or CO2 high pressure coils. Jacketed tanks with a chiller are very common, using superchilled media such as glycol for cooling.
Using a top entry mixer in your tank will provide turbulence and mass transfer, which can improve extraction yields by exposing more ethanol to more surface area of plant material and providing a mixing action. Adding a spinning basket allows you to remove most of the moisture out of the plant material without having to squeeze it. After draining the tank, the spinning basket acts just like a washing machine during the final spin cycle to remove the remaining ethanol (& the extract dissolved in that ethanol) from the plant matter.
Recirculating the ethanol and extract with a pump can provide turbulence and mass transfer to improve extraction rates and yields. Pump can then be used to drain the tank at the end of the cycle.
Supercritical CO2 extraction is perhaps more appealing than butane extraction simply because of its relative safety and the lack of harmful residual solvent in the oil
after processing. With a minimal environmental footprint, many favor supercritical CO2 extraction. CO2 extracts can be preferred for some applications because they are relatively flavorless, but that means they also lack the range of terpenes and minor compounds present in ethanol and butane extracts. Although CO2 is often the most desired method for making vape oil and distillates, the equipment is quite expensive and does run under high pressures in the 1500-5000 psi range.
What is NOT recommended is using butane and other potential dangerous solvents. For so long, extractions were created with butane, which boils at a lower point than other common solvents, including alcohol. Because of butane’s non-polarity, extractions containing specific cannabinoids and terpenes are easier to produce, since specific compounds may be drawn from the plant matter without co-extracting chlorophyll and other “undesirables.” However, butane is also famously flammable – think lighter fluid – and many explosions have occurred as a result of DIY butane extractions gone wrong. These safety concerns must be weighed when choosing the proper process for your business. Working with Butane requires more building modifications to meet the Class 1, division 1 spark proof lab for processing. Even when working in a well built lab, the risk of an explosion due to minor human error is still a real possibility.
Before taking the steps of buying equipment and setting up laboratory, there are very
important questions that need to be answered; i.e. What extracts need to be produced?
Shatter? Wax? Butter/Crumble? “Terp Sauce”? Distillate?
Shatter is a concentrate that is brittle and has a glass-like appearance. It is called
“shatter” because it should do just that if broken. Butane remains the most popular way to produce shatter, but it is important to keep in mind, this is unlikely produce a “solvent-free” concentrate and great care must be taken to purge the excess butane from the final product.
Wax, butter, and terp sauce are post-processing products that can be made with CO2 or Butane as well. They get these names because of the consistency of the extract which happens for a variety of reasons, but will not be covered in this article.
Distillate is a concentrate that is very potent and contains very little cannabinoids other
than primary cannabinoid targeted (THC or CBD). It is very thick and can be best compared to the consistency of cold molasses. Either Butane, CO2, or Ethanol Wash can be used to make distillate. Even if you start with Butane or CO2 extract, ethanol will still be used for a process called winterization/filtration (removing undesirable material from the crude oil), followed by ethanol recovery, then introduced to a still to create the end product: distillate. With that being said, starting with a ethanol wash is the most logical choice if the desired end concentrate is distillate or even Full Spectrum oil.
Whatever your desired end product, High Purity Extractions can help you select the right equipment for your laboratory.
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