Blogs

The Isolation of CBD

Posted on June 5, 2023

The Isolation of CBD

Introduction

Many processors perform CBD isolation to create a THC-free product for their end-user for a variety of reasons. For those who have had the opportunity to isolate CBD using crystallization, it is apparent that the material will readily form crystals, sometimes almost to a fault. Controlling this crystallization becomes quite important when the user is looking to create consistent and repeatable outcomes from their process. This article will focus on a high-level background of crystallization and why specific methods are recommended for isolating CBD.

Thermodynamic Background

Crystallization can occur due to the limited solubility of materials in a solvent. Many factors come into play (including temperature, solubility, concentration, etc.), but ultimately under the right conditions, many organic compounds will begin to form organized lattices, or crystals, which are a lower energy state than when dissolved in a supersaturated solution. By controlling the various factors of the process, the crystals can form with very high concentrations of the target molecule, excluding most impurities. The ability of an organic substance to crystallize is dependent on intramolecular and intermolecular forces. For certain compounds, the result of the solidification may instead form an amorphous solid or different polymorph of the isolated product.

Types of Crystallization

There are a few ways crystallization is performed, which include precipitation, evaporative crystallization, and cooling crystallization. Precipitation can be accomplished through a reaction, pH adjustment, or using anti-solvents. These methods do not seem to be common in isolation of CBD. Evaporative crystallization is performed by removing solvent until the material hits its saturation point and begins to nucleate. While effective, evaporative crystallization is not the most ideal method for isolating CBD due to the nature of the crystallization. “When using evaporative crystallization, the process is less controlled, which can lead to CBD being isolated as a paste which can, in turn, create more issues when the process is scaled,” says Ben Schilling, Tolling Manager at Pope Scientific. Evaporative crystallization also is required to be done at vacuum conditions to ensure the CBD will form a solid instead of staying in a liquid state.

Cooling crystallization takes advantage of the fact that many organic compounds have reduced solubility with reduced temperature. Pope Scientific’s recommendation for CBD isolation is to use a jacketed reactor and temperature control unit to bring the temperature of the solution down slowly. Eventually, the solution will become supersaturated. The formation of crystals in the supersaturated solution is dependent on many factors including any impurities that may be present, the mixing profile, and whether seed crystals are utilized.

Crystallization can also be done in batches or done as a continuous process. While continuous crystallization may come out on top when considering ROI, it does add validation complications for customers operating in cGMP environments.

Considerations During Crystallization

To ensure the saturation limits of the solution are not altered significantly it is important to purify the starting material as much as possible prior to crystallization. Many users will purify their cannabinoid extract by means of wiped film molecular distillation. This process will usually allow for a distillate product to be created at > 90% cannabinoid. This purification step will increase the likelihood of consistent crystallizations.

Mixing profile in the crystallizing vessel is also very important as this can have an impact on the nucleation (formation) of crystals vs the growth stage for crystals. Depending on the ultimate use of your crystalline product, certain particle sizes and particle size distributions may be beneficial. Agitators with good pumping capabilities as well as baffles in the reactor can result in more desirable crystal formation. It is important to balance minimum solvent use with the ability to have a flowable slurry that can be mixed.

The use of seed crystals can also be vital as this can impact the quantity and size of crystals formed. Seed crystals can also be critical in preventing the formation of amorphous solids or unwanted polymorphs. Since CBD readily crystallizes, seed crystals may not be necessary for most processors.

Isolation on a Nutsche Filter Dryer

Pope Scientific recommends using a dedicated reactor for the crystallization step as this will be specifically designed for good mixing. Additionally, while the capital cost can be reduced by using a Nutsche Filter Dryer for the crystallization step, this does run the risk of clogging the filter and causing cleaning issues.

Nutsche filter dryers are valuable tools in the GMP environment for filtering, washing, and drying. After a crystal slurry is created, the Nutsche filter-dryer can be used as a single container for the multiple unit operations that are required. This is beneficial because it eliminates the risk of contamination by eliminating any transfer steps. It also reduces the amount of equipment that must be validated as clean.

First, the slurry is transferred to the Nutsche where the “mother liquor” or supernatant can be separated from the crystalline product using a fine filter screen. The advantage of a Nutsche Filter Dryer over a standard filtration device is that it can be pressurized to speed along the filtering process and mother liquor can be recirculated allowing for the complete transfer of the crystals from the reaction vessel.

After the material is filtered, a pure solvent is typically added to remove any impurities that may be present on the surface of the crystals, often called a “wash” step. Washing is performed with either a spray nozzle or ring which allows for even distribution of solvent across the filter cake. If there is not an even distribution of solvent, channeling can occur, which will reduce the effectiveness of the wash. The washed crystals at this point should be of high purity.

These crystals can then be dried by applying heat and vacuum to the Nutsche filter dryer. For many crystals, the ability to apply vacuum in the Nutsche Filter Dryer is critical as the melting point of the crystals may be lower than the boiling point of the solvent. The agitator in the Nutsche allows for the cake to be smoothed which results in even drying and through proper process development and testing can yield a reliably solvent-free product.

While the methods and ideas described above do not delve into any new territory for organic chemistry, they are important concepts to consider when developing an isolation process. Often innovation is seen as an extremely important aspect of the cannabis industry, but it is important to consider tried and true methods when there is a need to meet cGMP requirements and put out a robust and consistent product.

For more information contact Pope today!

Determining Which Fractional Distillation Process to Use: Batch or Continuous Mode

Posted on January 31, 2023

Determining Which Fractional Distillation Process to Use: Batch or Continuous Mode

Introduction

Distillation is an important method for the separation and purification of liquids in a wide range of industries and laboratories.  For optimal purification in distillation, a vertical column is incorporated into the equipment with either a series of internal stacked plates (trays) or else filled with one of various types of structured or dumped-in packing.  The purpose of the trays or packing is to provide a high degree of vapor-liquid contact which results in multiple equilibrium stages or “theoretical plates”, each one leading to increasing purification all the way up the column, with the purest and lowest boiling point (BP) vaporized component(s) escaping the top of the column to contact a condenser where it leaves the column as a liquid distillate.  The overall result is that specific components of the starting composition have been separated, or fractionated, giving this process the name, fractional distillation.  Fractional stills often operate under pressure or vacuum and have a reflux device section for controlling and optimizing purity vs. throughput rate, however, these and several other topics of distillation equipment are not covered here. In this article, we will take a look at the two different types of fractional distillation; batch mode and continuous mode.

Batch Distillation Mode

Continuous Fractional Distillation Systems

Batch mode is the normal starting point of any distillation process and is the “simpler” of the modes.  Here, a fixed amount of feed material, (a batch) is loaded into a boiling vessel (pot), onto which is mounted a column with a condenser at the top.  The pot is heated and after a certain amount of time, the liquid begins to boil, and portions of it vaporize and travel up the column.  (One well-known example of batch mode is the traditional making of “moonshine” where a fermented mixture is loaded into the pot, heated, and an ethanol-enriched distillate is collected). The first feed components to vaporize are ones with lower boiling points (BP) than the others.  These components move up the column, with the lowest BP component in the feed becoming increasingly purified by means of fractionation finally being condensed and leaving the rest of the mixture as described above, to be collected in a distillate receiver.  This will continue until the first component of lower BP is depleted in the boiling pot.

At this point, if the process is allowed to continue, the next component of BP greater than the first begins to make the travel all the way up to the condenser to be condensed, leaving as another distillate fraction that can be collected in a different receiver than the first.  Some feed materials may contain many components and this means of separating several of them, one after the other, in order of increasing BP, can be continued until the desired product components have been collected at which point, the distillation process is ended by shutting off the heating of the boiling pot.

Examples of batch stills are many and can include anything from isolation of a flavor component in an extracted natural botanical source to recovering certain solvents from a waste mixture for reuse.  A key characteristic of batch mode is that the composition of the feed material in the pot is constantly, incrementally changing throughout the duration of the run.  The composition in the pot at the moment will be different an hour from now or even just a few minutes from now.  The distillate collected will also change in composition over time as each subsequent component is distilled away.  Thus, this is not a steady-state process.

In situations where the quantity of starting feed material becomes quite large, for example well beyond 1000 liters, and feed lots must be processed frequently, for example, at least every day, batch mode will become quite limited in addressing production requirements.  Another method for fractional distillation is then needed and this is when continuous mode must be considered.

Continuous Distillation Mode  

Continuous mode fractional distillation can handle very large quantities of feed without the need for very large boiling vessels.  Instead, feed is pumped at a set flow rate into the distillation system which has a column and condenser which can be similar to a batch-type setup.  However,  in this case, a reboiler replaces the boiling vessel and this is outfitted with apparatus for continuous discharge of residue, often referred to as a “bottoms stream”.  The feed is preheated and enters the column at a height selected to optimize the overall process efficiency.  Distillate leaves the system from the condenser, similar to the case of batch mode.  So, in continuous mode, there is one stream entering the system and two streams exiting the system, the distillate, and the residue.

A key characteristic of continuous mode is that the compositions of these streams and at any point within the distillation equipment do not change over time as in batch mode, instead they remain constant, in a steady state throughout the entire run, the duration of which may go on for a considerable time.  Oil refineries are a well-known example; these typically operate 24/7, being stopped only for maintenance or other technical reasons.  There are exceptions to the 3-stream scheme described above; for example, in addition to the distillate collected at the top of the column, there may be multiple take-off points (side-streams) at various heights of the column.  In the case of oil refinery columns, these will be multiple component cuts including gasoline, diesel, and mixed solvents in the upper column region, and oil cuts of increasing weight and viscosity as the locations get closer to the bottom of the column.  It is important to note that these are never pure single-component cuts, but collections of many components of somewhat similar BP, for example, one stream may become further processed to become 10W-40 motor oil, and another stream may be used to create a variety of lighter lubricants, etc.  The heaviest components of all become the materials used in tars, asphalts, and the like.

Other continuous fractional applications may involve feed streams with several, but far fewer individual components than are found in crude petroleum oil.  Examples include many specialty chemicals such as pharmaceutical intermediates and electronics materials manufactured in reactors.  The target product(s) may be somewhere in the middle of the range of the BP’s of several byproducts that must be removed.  For high-purity products, side draws cannot be utilized, these will not be pure enough.  To isolate pure components, more than a single column is needed, the number being dependent on the number of components in the feed.  For example, the first column may be used to distill away several components which are lower in BP than the desired product.  The residue can then serve as feed to a second column which will distill away the product plus a byproduct of BP near that of the product.  This distillate stream may be fed to a third column which separates the product away from the byproduct that is co-distilled from the second column.  This type of separation of pure components is more easily done with a single batch still if heat sensitivity is not a problem, (waiting for the product to start coming off the column and collecting it separately), however, as mentioned earlier, this is not practical with very large feed quantities; instead, a battery of staged continuous mode columns is called for.

There are many considerations that go into the design of a fractional column distillation system. These factors can vary depending on the scale at which you are manufacturing. When working at a commodity scale it often makes sense to manufacture in a continuous fashion, however, on the pilot and small production scale an important consideration is whether to use a batch approach. In addition to scale, there are a few other factors that play a considerable role such as the quantity of material, purity, energy use, and how many components need to be separated.  These are highlighted in the figure below:

Energy Usage

Energy consumption in continuous distillation is lower than that of batch distillation.  Heat recovery can be utilized, and the process loops optimized for both product quality and energy consumption. Energy usage can also be optimized by both preheating the feed material and selecting the best column entry point for the feed stream, reducing the condenser and reboiler duties.  In batch mode, more energy is required in startup and because much of the heat is applied to evaporating the same material portions multiple times; this effect is reduced in continuous mode operation.

 

Pope Continuous Fractional Distillation System

Pope Batch Fractional Distillation System

Process Development and Scaleup; Lab, Pilot Plant, and Production Scale

As mentioned, in nearly all cases, batch mode is the starting point for fractional distillation.  Even if the long-range goals call for very large production quantities and continuous mode installation will eventually be needed, new product development typically starts with lab scale and this will be batch mode.  Lab scale equipment with boiling vessels of less than 1 liter up to 12 liters is appropriate for process feasibility studies. The lab-scale distillation experimentation may be part of an extensive general product development project.  For example, it may be found that upstream chemistry and reactions need to be changed to allow proper distillation and other downstream operations work well, followed by more experimentation, etc.  If lab studies are successful, it is normally advisable to move on to stainless steel (or other higher alloy if necessary) pilot scale equipment.  This may include batch stills from a few liters in size up to 100 liters or more.  It may also include pilot scale continuous stills with column diameters from 1” to 12” and feed rates from 1 to a few hundred liters/hr. Equipment of the larger end of these ranges can also serve as small or mid-size production systems as needed.  Examples of such equipment are shown.

Pope Scientific offers batch fractional stills in glass from 1 to 22 liters and in stainless steel from 2 to 2000 liters or larger.  Continuous fractional still systems are available in stainless steel with from 1” to 24” column diameters.  All of the above equipment is normally designed and manufactured in skid-mounted modular turnkey form. Instrumentation can range from control elements only to fully integrated PLC control systems.  Semi-turnkey systems and core distillation components alone are also available.  During pilot plant studies, it may be found that the distillation system may need to be reconfigured somewhat in order to optimize the process.  Pope takes this into account in the design of pilot plants, for example, allowing the ability to add or decrease column height or addition of collection receivers, etc.  Control systems for continuous systems are more complex as there are several control loops required to achieve a steady state.  However, the programs required for batch systems can be more extensive than for continuous, depending on what the user wants to accomplish. This is because there are usually several time and event-based changes in operating parameters during the run which may be automated, with routines set up by the operator before the run begins.

Pope maintains a staff highly knowledgeable in applications assistance, chemical engineering, chemistry, and chemical equipment operation, providing the customer with a partner for matching processing needs to equipment optimized for the lab, pilot, or production project. In addition to the provision of equipment, Pope can offer lab and pilot scale studies, depending on the nature of the specific applications.  Experienced personnel in mechanical and electrical engineering, assembly, quality assurance, and documentation assure the equipment will work well from delivery and startup and will last for decades.

Understanding Short-Path, Fractional and Pope’s Wiped-Film Molecular Stills

Posted on April 7, 2022

Understanding Short-Path, Fractional and Pope’s Wiped-Film Molecular Stills

Oftentimes when people are considering distillation equipment for processing hemp and cannabis, there seems to be a lot of confusion and misuse of terminology with short-path stills and Pope’s wiped-film molecular stills.  We have explored some of the key points below.  

What is Molecular Distillation?  

Molecular distillation and short-path distillation are the same things. These both imply the use of high vacuum and a condensing surface in close proximity to a heated evaporation surface. For many applications such as cannabinoids and as well as other compounds with greater molecular weight and boiling points, if the distance is not close enough, the equipment will not work well, if at all. 

What does short-path mean? 

We discovered some people perceive the term “short-path” to imply a basic glassware setup involving a basic boiling flask with a neck leading to a condenser and a

Fractional distillation diagram

Image source: http://www.chemhelper.com/distillation.html

receiver flask(s), or else a similar variation called a KIugelrohr. These are oftentimes also referred to as pot stills, (pot as in a vessel, not in the cannabis sense), and are all considered batch mode apparatus. However, these only refer to one type (the simplest type) of short-path or molecular stills. There are other forms of short-path

setups including Pope’s continuous mode Wiped-Film Molecular Still (WFMS). 

Is a fractional still the same thing as a short-path still? 

Fractional stills are not short-path stills. Fractional distillation equipment implies the utilization of a vertical packed column providing multiple equilibrium stages or “theoretical plates”, requiring the condenser to be further away from the boiling container (reboiler) and reached only after the obstacle of the packed column. While this can be used to increase the purity of a distillate, it is instead a problem for heat-sensitive materials such as cannabinoids. Though Pope does offer fractional distillation equipment, the single theoretical plate of molecular stills is sufficient for most cannabinoid work and offers the least product degradation.

 

What are the advantages of a wiped-film still compared to a boiling flask short path setup? 

Now that we have a good understanding of short path, we want to dive into the advantages of Pope’s WFMS over a basic boiling flask type molecular short path still.

2” Standard Glass Wiped Film Still

Complete Molecular Still Package System with electric band heating (bands removed), external condenser, all utilities, plus optional feed pump.

One key advantage is that the Pope WFMS is a continuous mode, rather than batch mode still. This means that with larger or special flasks, or with liquid pumps, they can operate for extended periods of time with any quantity of feed material and with the same consistent product composition over time. The Pope WFMS is also scalable, such that when much larger quantities of material needs to be processed, larger versions of the same type of equipment can be utilized to accommodate the greater throughputs required. Batch mode stills such as the boiling flask short path still can be scaled but lose efficiencies due to heat and mass transfer limitations resulting in extremely long operation times and loss of product to degradation. 

In addition to scalability and continuous mode, another advantage is the Pope WFMS offers much less thermal degradation and greater product purity and yield. This is for two reasons. One, there is a very short residence exposure time to a heated surface – only a matter of seconds, compared to many hours in a boiling flask molecular still. And two, the WFMS has a highly efficient dynamic rotating wiped film action providing turbulent moving thin-film mixing compared to the limited, less dynamic liquid/vapor interface of a simple boiling flask apparatus. 

Have more questions on terminology or Pope’s Wiped-Film Molecular stills?  We are here to help answer your questions. Contact us to learn more or speak with a Pope team member.  

The Benefits of Utilizing Data Acquisition Systems in Distillation Processing with Yokogawa

Posted on January 25, 2022

The Benefits of Utilizing Data Acquisition Systems in Distillation Processing with Yokogawa

Data acquisition systems (DAQ) have been around for a long time; however many people aren’t familiar with this technology when inquiring about distillation equipment. Programmable Logic Controllers (PLCs) are used often in chemical processing for controlling key variables such as pressure, flow rates and temperature. While most PLCs will have some sort of data logging capabilities, it is typical that the software associated with the PLC is very cumbersome. Often a programmer will have to spend a good deal of time to incorporate the basic trend information that would come standard on a DAQ system. In addition, data logging on a PLC is often just a CSV file that is dumped to a location after one run. The CSV file must then be further manipulated to show the data on a graph or chart. An actual data recorder can do a much better job with the visualization of data without hours of additional programming. A DAQ system allows the user to look back at any timeframe of data from 60 seconds to possibly several days prior. This data can also be set to be shown as trend information, bar graphs or just plain figures straight out of the recorder. A DAQ system can exist as hardware within a control panel in which it is viewed from a web browser or as external hardware with its own housing touchscreen control. Having such ease of access to these heavily customizable reports can prove to be very useful to an operator, which is why Pope likes to include both in our control systems.

Having hardware and software record data for you, as opposed to someone in the lab handwriting these bits of information, provides many benefits. Ease of access to data can be a strong point for the recorders. If a DAQ system is uploading this information to a hard drive or server, there are many ways this information can be shared and analyzed throughout a group or company from remote locations. This data can be used to ensure reliability or to improve process efficiency. Having access to this data also allows the user to make predictions in maintenance. For example, if a certain heating or cooling element starts to take more time to reach its target temperature, it could imply that that element is starting to fail. Knowing this ahead of time allows a company time to order replacements before a failure actually occurs. This avoids any sort of downtime.

Yokogawa GX20 – image source yokogawa.com

Most DAQ systems will have similar capabilities as those mentioned above – so why do we specifically like Yokogawa’s DAQ? The two main reasons are its easy-to-use interface as well as its ability to comply with GMP environments. Yokogawa has done an excellent job incorporating universal gestures into its touchscreen technology. The same swipe and pinch motions people use every day on their cell phones are incorporated into their recorders. The display is very intuitive in addition to being very bright and colorful. There is no shortage of customization options when it comes to viewing your data. Bar, trend, and digital graphs can be set up to view whatever variables are desired. As noted, the DAQ can be connected via ethernet to view data in real-time from anywhere, or more traditionally exported on a scheduled basis. This data can also be exported in different files types to be observed in other means. In regards to its GMP capabilities, Yokogawa DAQ systems can be compliant with CFR 21 part 11. This specific compliance is the FDA’s regulations for electronic documentation and electronic signatures. Yokogawa’s advanced security add-on allows the users DAQ system to contain an encrypted data file to prevent any manipulation to the data recovered. It’s a one-way road that only allows data to be exported out in an XLS file type. This add-on also contains an onboard audit trail that tracks what changes are made, who made them and when they were made allows for full traceability.

For all of these reasons, Yokogawa DAQ systems are a great asset to distillation equipment. Next time you’re inquiring about a Pope distillation system, be sure to ask how Data Acquisition Systems can be used with your process. Our experts are available to answer any questions and provide recommendations.

Optimize Your Cannabinoid Production with Pope’s Distillation Processing Services

Posted on July 7, 2021

Optimize Your Cannabinoid Production with Pope’s Distillation Processing Services

If you’re considering adding distillation to your cannabinoid production or require help in distillation process improvement, reach out to Pope.  In addition to our well-known wiped-film molecular distillation equipment product lines, Pope runs a very active toll distillation services department.

The tolling department includes a range of toll production stills with throughputs up to 230 kg/hr, pilot plant process development equipment and lab-scale feasibility testing stills. Some of the many industries served include foods, flavors, fragrances, bio-materials, extracts, pharmaceuticals, edible and essential oils, cosmetics silicones, lubricants and polyglycerides.

Pope has many decades of experience in wiped-film operation and has harnessed that knowledge to assist our customers in developing, optimizing and commercializing their distillation processes.  We’ve been running numerous trials and piloting of a variety of different cannabinoids with customers’ feedlots for several years.  Our trials and piloting help determine what improvement in purity, yield, color and clarity is possible through distillation.  Pope operates a 2” lab wiped-film unit to conduct trials for our customers and we are capable of following distillation results by Gas Chromatography (GC).  Once your material has undergone trials, we can help suggest opportunities for improvement based upon past experience.

In addition to lab trials, Pope has extensive experience in process development and scaling studies in pilot scale and in performing toll processing for customers who would prefer to outsource to Pope to distill their cannabinoid feed rather than purchasing and running their own equipment.  (This is also a great opportunity for start-ups who want to begin producing their product before they build and run their own lab.) Pope is licensed by the FDA in food GMP and is also kosher and halal certified.  We have a Hemp Processing License with the state of Wisconsin and are able to trial any cannabinoid feed that has a Fit for Commerce Certificate.

Want to know more? Please contact us to discuss your testing and tolling needs.Pope Toll Processing

Using a Mass Balance to Evaluate Your CBD Distillation Process

Posted on May 4, 2021

Using a Mass Balance to Evaluate Your CBD Distillation Process

If the average person was asked to do a mass balance on a system, they might not quite understand what is required. However, for chemical engineers and industrial process chemists this is something learned quite early in their curriculum. While it is a tool often used by chemical engineers, there is no reason why it should not be part of any processor’s toolbox.

For processes involving chemical reactions, the mass balance is written out as:Pope Mass Balance Illustration

INPUT + GENERATION = OUTPUT + ACCUMULATION + CONSUMPTION

However, when you are just using separation equipment (such as a wiped-film molecular still for distillation), the equation gets simplified to:

INPUT = OUTPUT + ACCUMULATION

Then, by defining the boundaries of a system, it becomes possible to check where your material is going which can allow you to make better decisions and optimize your process.

Let’s assume you are running a wiped-film molecular still to create CBD distillate. The INPUT to the still will be the feed material (the crude). The OUTPUT of this separation will be terpenes, residue, and CBD distillate. The ACCUMULATION would be any residual material left in the still. There are other outputs; the ethanol collected in the cold trap and any material that is lost through the vacuum pump, however, to simplify this exercise we will lump these into the accumulation and simply define them all as material loss.

While losses to accumulation are important, wiped film stills do not have miles of process piping, so overall this should not be a major concern on the equipment. However, by adding some analytical data to the mass balance much can be learned about your operation.

Example:

Prior to distillation, you have your crude CBD extract analyzed and the lab results come back indicating the material is 65% CBD by mass. You load the feed flask on your system with 2,000 grams of the material. You perform your first distillation and remove 160 grams of terpenes. On your second pass you get 1,155 grams of distillate and 635 grams of residue. When the lab results on your distillate come back, they show 90% CBD by mass. This seems good, but a mass balance will allow you to best review this.

For a Very Simple Mass Balance, You Have:

mcrude = mterpenes + mdistillate + mresidue + mloss  (1)

Where:

mcrude = mass of crude

mterpenes = mass of terpenes collected

mdistillate = mass of distillate collected

mresidue = mass of residue collected

mloss = material lost (to accumulate, transfer, etc.)

This yields 50 grams of material that is considered lost. Which could either be escaped ethanol or material that sticks as residual in the system (a common occurrence with high viscosity fluids).

Since there is not a large amount of material that was lost, it is now time to look at the amount of CBD you have recovered, also known as your yield. First, you must determine how much CBD is present to start, using equation (2):

mCBD-C = mcrude * CCBD-C (2)

Where:

mCBD-C  = mass of CBD in crude

mcrude = mass of crude

CCBD-C = CBD Concentration in crude (mass %)

This equation shows that 1,300 grams of CBD are present in your crude. A similar equation can be used to determine the amount of CBD in your distillate:

mCBD-D = mdistillate * CCBD-D  (3)

Where:

mCBD-D = mass of CBD in distillate

CCBD-D = CBD Concentration in distillate (mass %)

Leading to a total of 1,039.5 grams of CBD in your distillate. To calculate the yield of your process you then use Equation 4:

% Yield = mCBD-D ÷ mCBD-C  (4)

The percent yield from this distillation is approximately 80%, which would be considered quite sufficient. By further calculation, you can also estimate the amount of CBD that remains in your residue. We will assume that the 50 grams of lost material were at 65% CBD content, like the crude, meaning that 32.5 g of CBD where “lost”. By Equations 5 and 6, you can assume your remaining residue contains 228 grams of CBD or is 36% CBD (mass %):

mCBD-R = mCBD-C – mCBD-D – mCBD-L  (5)

Where:

mCBD-R = mass of CBD in residue

mCBD-L = mass of CBD lost

CCBD–R = mCBD-R ÷ mresidue (6)

Where:

CCBD–R = CBD concentration in residue (mass %)

A great amount of processing in the cannabis industry is performed without much attention to mass balancing and utilizing before/after analyses between process steps.  In many of these cases, the company will get by, obtaining adequate purities and (often unknown) yields.  A somewhat careful operator will often be able to “get the job done”.  However, consistent utilization of the principles of mass balancing, together with obtaining and studying analyses of every batch and run will allow an OK  operator to become an excellent operator.  This person will be able to plan parameters as well as strategies for each run, resulting in optimal purity and yield, leading to lower costs, better product quality, at better pricing, all eventually leading to greater profit for their company than their competitors.

Using a Mass Balance to Evaluate Your CBD Distillation Process

Posted on May 4, 2021

Using a Mass Balance to Evaluate Your CBD Distillation Process

If the average person was asked to do a mass balance on a system, they might not quite understand what is required. However, for chemical engineers and industrial process chemists this is something learned quite early in their curriculum. While it is a tool often used by chemical engineers, there is no reason why it should not be part of any processor’s toolbox.

For processes involving chemical reactions, the mass balance is written out as:

INPUT + GENERATION = OUTPUT + ACCUMULATION + CONSUMPTION

Pope Mass Balance Illustration

However, when you are just using separation equipment (such as a wiped-film molecular still for distillation), the equation gets simplified to:

INPUT = OUTPUT + ACCUMULATION

Then, by defining the boundaries of a system, it becomes possible to check where your material is going which can allow you to make better decisions and optimize your process.

Let’s assume you are running a wiped-film molecular still to create CBD distillate. The INPUT to the still will be the feed material (the crude). The OUTPUT of this separation will be terpenes, residue, and CBD distillate. The ACCUMULATION would be any residual material left in the still. There are other outputs; the ethanol collected in the cold trap and any material that is lost through the vacuum pump, however, to simplify this exercise we will lump these into the accumulation and simply define them all as material loss.

While losses to accumulation are important, wiped film stills do not have miles of process piping, so overall this should not be a major concern on the equipment. However, by adding some analytical data to the mass balance much can be learned about your operation.

high terpene full spectrum cbd extracts in pope cannabis distillation flask

Image source: Vext Science  www.vextscience.com 

Example:

Prior to distillation, you have your crude CBD extract analyzed and the lab results come back indicating the material is 65% CBD by mass. You load the feed flask on your system with 2,000 grams of the material. You perform your first distillation and remove 160 grams of terpenes. On your second pass you get 1,155 grams of distillate and 635 grams of residue. When the lab results on your distillate come back, they show 90% CBD by mass. This seems good, but a mass balance will allow you to best review this.

For a Very Simple Mass Balance, You Have:

mcrude = mterpenes + mdistillate + mresidue + mloss  (1)

Where:

mcrude = mass of crude

mterpenes = mass of terpenes collected

mdistillate = mass of distillate collected

mresidue = mass of residue collected

mloss = material lost (to accumulate, transfer, etc.)

This yields 50 grams of material that is considered lost. Which could either be escaped ethanol or material that sticks as residual in the system (a common occurrence with high viscosity fluids).

Since there is not a large amount of material that was lost, it is now time to look at the amount of CBD you have recovered, also known as your yield. First, you must determine how much CBD is present to start, using equation (2):

mCBD-C = mcrude * CCBD-C (2)

Where:

mCBD-C  = mass of CBD in crude

mcrude = mass of crude

CCBD-C = CBD Concentration in crude (mass %)

This equation shows that 1,300 grams of CBD are present in your crude. A similar equation can be used to determine the amount of CBD in your distillate:

mCBD-D = mdistillate * CCBD-D  (3)

Where:

mCBD-D = mass of CBD in distillate

CCBD-D = CBD Concentration in distillate (mass %)

Leading to a total of 1,039.5 grams of CBD in your distillate. To calculate the yield of your process you then use Equation 4:

% Yield = mCBD-D ÷ mCBD-C  (4)

The percent yield from this distillation is approximately 80%, which would be considered quite sufficient. By further calculation, you can also estimate the amount of CBD that remains in your residue. We will assume that the 50 grams of lost material were at 65% CBD content, like the crude, meaning that 32.5 g of CBD where “lost”. By Equations 5 and 6, you can assume your remaining residue contains 228 grams of CBD or is 36% CBD (mass %):

mCBD-R = mCBD-C – mCBD-D – mCBD-L  (5)

Where:

mCBD-R = mass of CBD in residue

mCBD-L = mass of CBD lost

CCBD–R = mCBD-R ÷ mresidue (6)

Where:

CCBD–R = CBD concentration in residue (mass %)

A great amount of processing in the cannabis industry is performed without much attention to mass balancing and utilizing before/after analyses between process steps.  In many of these cases, the company will get by, obtaining adequate purities and (often unknown) yields.  A somewhat careful operator will often be able to “get the job done”.  However, consistent utilization of the principles of mass balancing, together with obtaining and studying analyses of every batch and run will allow an OK  operator to become an excellent operator.  This person will be able to plan parameters as well as strategies for each run, resulting in optimal purity and yield, leading to lower costs, better product quality, at better pricing, all eventually leading to greater profit for their company than their competitors.

Methods to Produce Cannabinoids

Posted on April 6, 2021

Methods to Produce Cannabinoids

Cannabinoids have been used by humans for millennia. All the while, the source has been plant-derived, (phytocannabinoids), as these have been the most accessible for consumption. However, with expanding research and access due to changing laws, alternate methods for creating cannabinoids have come to the forefront.

element table of cannabinoids

There are three major methods in which cannabinoids are created. Most of the cannabinoids produced for human uses are made by growing plants in the genus Cannabis, which through great efforts in agro-science now can be tailored to have specific ranges of cannabinoid content. There have also been many scientists who have taken the time to develop synthetic pathways for cannabinoids, which have been utilized in production, principally for pharmaceutical use.  If interested in technical details on this, one of several articles can be found here.  Recently there has also been research focused on using modified single-cell organisms to create a desired cannabinoid.

While it is not too likely that you will see synthetic or bio-synthetic cannabinoids on the shelves of your recreational dispensary soon, there is reason to believe these manufacturing methods will eventually have their place in the cannabinoid industry. It is well known that the quantification of cannabinoids is an essential part of industry both for regulatory purposes, for the connoisseur looking for very specific outcomes from consumption, and for specific pharma use. Therefore, standards for testing labs are needed and these pathways may prove to be more cost-effective for producing high purity substances.

 
yeast under a microscope

(Image: yeast under a microscope)

Medical developments as cannabinoids are further studied may also push these production methods to the forefront. For example, strains have been developed in agriculture to create plants high in THC, CBD, and CBG, however, the pharmaceutical industry often demands repeatability which may be more likely from synthetic or bio-synthetic sources. Also, there may be limitations to what can be harnessed from plants. Suppose cannabinoids that are only produced in fractions of a percent in a plant are found to be extremely important in medical treatments. In that case, the best method for production may be using a single-cell organism.  Such biobased and fermentation means of production have been proven for a myriad of products in several industries, so one might argue that this was inevitable.

While consumers may stick with Phyto-based cannabinoids in the near term, there is a need to at least consider how these production methods may impact the cannabinoid industry.

 

Customizable Turnkey Vessel Systems

Posted on February 12, 2021

Customizable Turnkey Vessel Systems

 

Pope Turnkey Cannabinoid Processing System

Turnkey System for Reaction and Processing of Synthetic Cannabinoids

Pope offers fully integrated processing systems custom-engineered for many specific or general-purpose applications. Systems can incorporate reactors, crystallizers, blenders, homogenizers, dispensers, decarboxylators, filters, stills, evaporators, portable or stationary storage vessels, and more, configured in multiple-stage process skids, including instrumentation and controls. Built for high purity, food, and pharmaceutical use to ASME BPE and Sec VIII ratings (plus available CRN and CE), this turnkey equipment is ready for installation and for high-performance cannabinoid, edible, and other materials manufacturing.

For each custom-built system, Pope’s highly specialized engineers provide guidance throughout the entire project, including process development, engineering, installation, training, technical support and, we are told, the best, most comprehensive documentation packages in the entire cannabis industry! After-sale applications, technical and sales support is first-rate and is always available.

Have ideas on equipment you would like for your facility? Run them by our application professionals to help complete the concepts and provide proposals. Rely on Pope’s 60 Solution Driven years of experience in providing satisfied customers world-wide with quality equipment.

pope cannabis distillation manufactures homogenizer systems for the cannabis industry

Nutsche Filter Dryers for Producing Cannabinoid Isolate

Posted on February 3, 2021

Video: Nutsche Filter Dryers for Producing Cannabinoid Isolate

In this video, Pope’s Process & Sales Engineer, Ben Kultgen, introduces Pope’s Nutsche Filter-Dryer for the final isolation of cannabinoids.

Many cannabinoid isolates are created by taking a distilled extract, combining it with a solvent, and then using temperature change or evaporation to create a slurry of formed crystals and solvent.

The Nutsche filter dryer comes into play after this slurry is created. The slurry can be transferred into the Nutsche where the filtrate, also known as mother liquor, is forced through a bottom filter disc, resulting in a wet cake of crystalline cannabinoid. The Nutsche Filter-Dryer is more diverse than a simple filter as it also has a spray nozzle to allow for the isolate to be washed with a clean solvent, a liquid jacket for controlled heating or cooling, pressure capability for the efficient discharge of solvent, vacuum capability for drying solvent out of the filter cake, (aided by heat).

The design of the Nutsche for cannabinoid processing can include a special raisin/lowering full diameter cake agitator to assist the release of crystal surface impurities during washing and breaking up cake lumps to assist in efficient drying.

The Nutsche Filter-Dryer design provides an efficient single-vessel location for several process steps to occur with containment, eliminating contamination and exposure and unnecessary extra handling,

If you would like to learn more about Pope Scientific’s Nutsche filter dryers for your cannabinoid material, or any of our other cannabis processing equipment, please reach out and our technical sales team will be happy to assist you. Learn more and view our Turnkey Isolation Nutsche Reactor System.

Post-Extraction Cannabinoid Decarboxylation and Its Relationship To Solvent Removal

Posted on December 11, 2020

Post-Extraction Cannabinoid Decarboxylation and Its Relationship To Solvent Removal

Introduction to Cannabinoid Decarboxylation

During the course of post-extraction cannabinoid processing, one of the steps normally (though not always) carried out is the conversion of the non-active acid form of the cannabinoid(s) to the active form, prior to final product completion. This is accomplished utilizing a chemical reaction named decarboxylation, (“decarbing” for short). The reaction can be performed at a choice of two different stages in the processing sequence; either with the biomass prior to extraction or else with the liquid form after extraction. In either case, the reaction is driven by heating to increased temperatures (normally between 110° and 150°C) for a specified amount of time (normally between 0.5 and 3 hours), though some operators use more extreme parameters. The reasons for choosing between the pre-extraction and post-extraction methods and the specific parameters used are various and depend on the processor’s feedstock and product goals. Post-extraction decarbing is more common and is the method covered here.

 

The Reaction & Efficiency

The reaction takes place at a position on the cannabinoid molecule containing a carboxyl group (-COOH). Heat induces substituting the carboxy group by the single hydrogen atom (-H). In the process, the carbon and the two oxygen atoms break away from the cannabinoid as carbon dioxide (CO2) in gas form. For the case of post-extraction decarbing, one of the most efficient known methods is to have a batch of liquid extract contained within a stainless steel reaction vessel which is heated under vacuum conditions and rapidly stirred.

The purpose of agitation is three-fold:

  • Agitation helps transfer and distribute the heat required for reaction rapidly, from the vessel walls to the liquid.
  • Agitation enables the released CO2 to better dissipate out of the liquid and into the vapor space, which is under vacuum, helping the reaction to “go to the right” and be conducted efficiently.
  • Agitation makes other gases and evaporating solvents efficiently escape from the liquid to the upper space for removal from the vessel.

CO2 and Ethanol Dissipation

In the majority of cases, the non-active extract will also contain some amount of solvent ethanol, usually as a result of either solvent extraction and/or winterization with chilled ethanol and filtering for wax elimination. After those steps, the bulk removal of the ethanol will have been carried out typically with rotary evaporators for smaller scale or with falling film evaporators in larger-scale operations. However, in many cases, the ethanol is not sufficiently removed to the levels achieved with more careful processing. Often, a decision is made to remove the remainder during the decarbing process since it will conveniently be under raised temperature and vacuum. Thus, the decarbing apparatus serves double duty as a reactor and as an evaporator, discharging both CO2 and ethanol.  However, it is possible, and fairly common, to leave “too much” ethanol in the extract prior to decarbing, resulting in lingering ethanol in the extract, even with a successful decarbing cannabinoid conversion. This occurs due to weak hydrogen bonding of alcohols to organic compounds such as cannabinoids, effectively increasing the alcohol’s boiling point. Too much ethanol remaining in the distillation feed batch can impact the effectiveness of terpenes removal in the 1st distillation pass, with a spillover effect impacting the cannabinoid distillation in the 2nd pass, resulting in a product of lesser quality and yield.

A Turnkey Approach

Pope Scientific provides decarboxylation reaction equipment and complete turnkey systems designed for optimal processing of any required size range to the cannabinoid industry. A complete system includes a jacketed 316L stainless steel reaction vessel with ASME vacuum and pressure rating and food or pharma grade finish, a matching agitator, a heating circulator, condenser, dry running vacuum pump, and instrumentation. Controls can range from simple manual type to automated PLC stations with advanced data handling, depending on the customer’s budget and preferences. All parameters and sequences can be preprogrammed, including an increasing vacuum level during the process, reaching better than 0.5 torr near the end for better subsequent distillation processing. Options include portability and XP Div. 1 or 2 ratings. For increased convenience, the decarbing vessel can be made portable to double as a feed vessel for a Pope Wiped-film Molecular Still.

Optimizing Evaporation Beforehand

It is mentioned above that rotary evaporators and falling film evaporators often do not completely remove ethanol to ideal levels, (<0.1%).  Pope can provide guidance for dealing with these problems.  For various reasons, it is not possible to effectively decrease solvent from high levels to very low levels, (e.g., from 80% to 0.1%) in continuous mode evaporators in a single pass. Pope offers multistage evaporation systems incorporating either a falling film evaporator or a wiped film evaporator for the first stage and a smaller wiped film evaporator for the second stage. This equipment is available in fully turnkey integrated and automated skid-mounted systems.

Contact Pope today or request a quote to discuss your current or future decarboxylation and evaporation equipment requirements.

How Volatiles can Affect your Distillation Process

Posted on August 19, 2020

How Volatiles can Affect your Distillation Process

By Ben Kultgen, Process and Sales Engineer, Pope Scientific

 

In this video Ben, process and sales engineer with Pope Scientific, gives an overview of how volatile materials can affect your distillation process, and how you can identify them.

If you have run wiped-film equipment before, you likely have run into vacuum issues at least once in your career. Weak vacuum can often be caused by a leak in your system, which is normally readily found, but can be sometimes frustrating to fix. (If you do need help on your Pope system, we have a team of technical resources who can help you out with this.) However, if your system is vacuum tight and the pressure increases dramatically above the desired range when feeding material to the still – what might be the issue? The cause is likely the presence of volatiles in your feed material.

 

What is Actually Happening:

Specifically, when discussing the processing of Cannabinoid extract, you are often conducting two passes to yield your high purity distillate. The first pass focuses on taking out terpenes and the second pass focuses on bringing the cannabinoid distillate away from the heavy waxes, chlorophyll, and sugars.

When you have volatile materials such as ethanol or dissolved gasses in your feed, they take up the vapor space on your first pass and weaken the vacuum, preventing all of the terpenes from being distilled, and these will be in the feed for the second pass.

Even if you leave a small amount of terpenes in your material for the second pass, you likely will not get as high of a distillate yield as you would have had the terpenes been properly removed. This directly impacts your bottom line.

Without proper devolatilization you may also negatively impact the quality of your distillate. Often when customers find streaks occurring in their distillate it is due to flashing. When you have two materials with much different boiling points, you may see flashing if the mixed material is exposed to too much heat or vacuum. A practical example of flashing is when you put water into a frying pan with hot oil. When the water is introduced, it immediately vaporizes. When it vaporizes it not only flashes the water but carries oil along with it. The same thing will happen with cannabinoid distillation when there is either dissolved gases, ethanol, or light terpenes present, and you operate at cannabinoid distillation conditions. When the light materials flash, they will pull undesired materials like chlorophyll and waxes with.

How Users try to Compensate:

Often when vacuum issues arise due to the presence of volatile materials, customer attempt to compensate in several ways by attempting the following: Running at higher temps, feeding at very slow flow rates, or trying to bully the vacuum levels down by purchasing larger and more complex vacuum pumps.

In the real world this can sometimes help, but it is not the ideal way to process. Whenever there are materials present with a boiling point difference of around 30 C or greater, the solutions that should be considered include multiple (more than two) passes, and/or prior removal of solvent to less than 0.1%. You can consult with Pope on the various methods that can be utilized to accomplish this prior to the first distribution pass.

Hopefully, this introduction to the impact of volatile materials on your process has been helpful. If you have further questions, please contact Pope Scientific to learn more about our wiped-film molecular distillation equipment and processes. Stay tuned, we have more helpful videos to come.