What Are The Advantages Of Short Path Distillation

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The natural world is almost never simple. Finding something that is a pure compound almost never exists on its own. However, in the world of chemistry, it is possible to isolate and concentrate chemical compounds. In fact, it is even possible to take complex mixtures found in the natural world and simplify them into their purest constituents. This is possible through a process called distillation. Distillation is essentially the isolation and separation of individual compounds from a complex mixture based on their boiling point, through continual evaporation and condensation. One of the most common forms is called short path distillation, which has clear advantages for both the user and finished product. [1]

How does Short Path Distillation Work?

Short path distillation gets its name from the short distance that the solution has to travel. Depending on the precise configuration of equipment, this distance is often only a few centimeters, meaning it only requires a small amount of lab space to be performed. To start, the solution of extraction material is added to a flask. This flask serves as a feeding vessel to the distillation system.

Slowly, the temperature is raised, which allows for evaporation to occur. To lower the amount of heat necessary to achieve vaporization, short path distillation is performed putting the system under vacuum. [2] Within the vacuum, ambient pressure is raised, utilizing aspects of Charles’ Law to lower the boiling point of the material to be distilled. [3] As the extraction material vaporizes, it rises into a fractionalization tube, where it mixes with additional vapors like water or air to aid in the cooling and condensation of the material. [4]

This condensed material is siphoned off into a separate flask where it transitions from a vapor back to a liquid. In order to ensure a purity of the distilled material, the additional vapors used to cool the extraction material are separated out of the vacuum. This creates two separate flasks, one with a concentrated extract and the other with the distilled and recondensed products that can both be unwanted byproducts or precious pure compounds of interest. To ensure the highest purity and the maximum yield, this process of short path distillation can be performed multiple times.

Advantages of Short Path Distillation

There are several advantages to short path distillation compared to other distillation methods. As the name implies, the short path means that the extracted material only has to travel a few centimeters. [5] This means that the equipment needed only takes up a small amount of space, and can be performed with basic flasks, tubes and heating sources. The set-up, while simplified and small, allows for continuous feeding of extraction material to the distillation system. [6] This means that the process can be automated and can shorten the time needed to isolate the materials.

In addition to the simplified arrangement of equipment, the vacuum provides some advantages as well. First, by reducing the pressure in the equipment, the boiling and vaporization point of the extraction material is lower than it would be at a standard external pressure. This means that less heat is needed to start the distillation, which can lower costs over an extended time frame. There is a second advantage to using less heat, short path distillation works exceptionally well with products that are sensitive to heat. [7]

On top of the lower heat exposure, short path distillation’s vacuum also leaves both purified extraction materials and purified solvents. [8] This allows for various solvents to be recycled, cutting costs even further. Finally, in addition to the ease of use, continuous feeding, and benefits from the vacuum, short path distillation creates high yields of final products with exceptional levels of purity. [9] This advantage is twofold: first, whatever the desired extract is has fewer flaws and contaminants, making it more appealing for any further uses. And second, there are less harmful byproducts in the leftover material, because any other additional materials within the initial solution can either be isolated themselves.

Common Applications of Short Path Distillation

Short path distillation is one of the most commonly used procedures in the extraction process. This is due to its various advantages, but its ubiquity breeds familiarity. In the food industry, this type of distillation is most commonly used with various oils. This may come in the form of concentrated essential oils or deodorizing fats and oils from animal products. [10][11]

Additionally, alcoholic beverages rely on distillation to remove the methanol from the initial plant mash, but also to infuse the beverage with plant aromas in steam current. [12] In a similar vein, the entire perfume industry uses short path distillation. [13] Starting with a complex mix of aromas, the final fragrances are a product of the concentration and purification of the essential ingredients into a small bottle.

Another industry that prioritizes taste and smell is the cannabis industry. [14] Using short path distillation allows cannabis extracts to preserve complex terpene profiles while avoiding any loss of flavors due to overexposure to heat. Finally, the lower usage costs make it the preferred distillation method for several heavy industries. In petroleum refinement, hydrocarbon chains need to be separated from crude oil to convert to valuable petroleum. [15] As previously stated, volatile products that are sensitive to heat utilize the increase in pressure to lower the amount of heat needed. The same principle also applies to the related petrochemical industry. Hydrocarbon chains also need to be removed to create polyethylene and polyurethane. [15][16] Because these products are also sensitive to high temperatures, short path distillation can be used effectively with minimal risk.

References:

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