Knowledge:A few advantages of supercritical carbon dioxide

First, can you tell us a little bit about supercritical CO 2 - what is it and what does it involve?

Supercritical CO2 (Supercritical CO2 Extraction Machine company) is simply carbon dioxide that has been pressurized and heated to above its critical point (31.1 oC, 1081 psi). The fluid has many useful properties, including low viscosity, high density, very low cost and leaves no residual solvent. The carbon dioxide used in the supercritical CO 2 process is collected from other large-scale industrial processes and transferred only through extraction or separation equipment. Due to its neutral environmental footprint, supercritical CO 2 is used in many green chemical processes.

Supercritical CO 2 is a very popular solvent for industrial processes because it is very inexpensive and because it is not toxic and is not considered a "volatile" solvent. For these reasons, supercritical CO 2 is described as "generally recognized as safe" (GRAS), which is an important classification when considering industrial applications.

What are the advantages of supercritical CO 2? On the other hand, what are the challenges that come with it?

Carbon dioxide has the advantage of being non-flammable and non-toxic, which other common solvents usually do not have. The downside of this solvent is that it requires relatively high pressure compared to hydrocarbon solvents. For example, a quality supercritical CO 2 extractor will operate at 3800 psi or higher. High pressure machines can operate at 15,000 psi or higher. A lot of engineering and expensive machinery is required to generate and control these high pressures. The benefit is that the solvent cost is a fraction of that of hydrocarbon solvents and does not require operation in a hazardous location rated environment.

In addition to GRAS, which is generally considered safe, and the fact that it is so inexpensive, supercritical CO 2 has many advantages in terms of its "tunability," which means incremental changes in temperature and/or pressure, i.e., the "behavior" of the solvent when used for extraction and separation It has a high selectivity when used for extraction and separation. A particular challenge with supercritical CO 2 is that some "undesired" extraction/separation results may occur due to its relatively high operating pressure. For example, through plant extraction, supercritical CO 2 extracts many fats and lipids from plant material, which is often undesirable.

What is a simpler way to determine whether you should use supercritical or subcritical methods? What is the difference?

"Subcritical" simply refers to a state of matter that is below the critical point. For carbon dioxide, this can be solid phase, liquid phase or gas phase. For extraction, liquid phase CO2 is usually used because it operates at a lower temperature. The disadvantage is that the solubility of liquid carbon dioxide is several orders of magnitude lower than supercritical carbon dioxide. The only way to determine whether supercritical or subcritical carbon dioxide is the preferred method is to perform experiments and collect data. We offer process development services to our customers on a fee-for-service basis.

A simple way to determine if supercritical CO 2 is right for you involves answering the following questions.

What is the application? Supercritical CO 2 is not an effective solvent for all separations, however, the list of effective applications is extensive.

What is a viable method for your facility/laboratory? Some laboratories prohibit the use of volatile solvents such as alcohol or LPG (liquefied petroleum gas), making supercritical CO 2 a viable option for more laboratories.

What specific products are you working on? Some products are better suited to use subcritical CO 2, although the extraction process is usually very slow compared to supercritical CO 2.