How volatiles can affect your distillation process

Published on: August 19, 2020

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.