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Compressed fluid technologies
in the EU 7FWP

There are a number of calls which involve green fluid technologies ...

Micronization

Micronization techiques utilizing supercritical carbon dioxide is a large family, but all processes benefit from the unique kinetic (or dynamic) properties of fluids, and the solvating power is pressure/density dependant. In short, compounds dissolved in SC-CO2 rapidly precipitate when solvating power of the fluid is reduced by pressure/density change.


The precipitation process in fluid phase is much faster than the crystallization process, thus particles do not have time to crystallize.
As a result micro- and nano-sized particles of amorphous or semi-crystalline morphology are formed.

 

Depending upon the instrumental design and process conditions different acronyms are used. The most usual one is RESS Rapid Expansion of Supercritical Solutions.

RESS is very practical when the compounds dissolve in SC-CO2, but most compounds of industrial interest, such as pharmaceuticals, catalysts, and precursors of electronic materials do not. In these cases SC-CO2 might be of use as antisolvent. In this process family, compounds to be micronized are dissolved in liquid solvent which is miscible with SC-CO2. When SC-CO2 is added, SC-CO2 dissolves in the liquid thus reducing its solvating power. In the end precipitation occurs, because the liquid solvent- SC-CO2 mixture is not any more dissolving the compounds. This later sentence illustrates the fact, that compounds soluble to mixtures of the particular liquid solvent and SC-CO2 are not readily micronized using Supercritical AntiSolvent (SAS) techniques. Because the efficient mixing of the liquid solvent and SC-CO2 is one of the key points of antisolvent micronization processes, numerous process designs (and their acronyms) have been shown in the patent and scientific publications.

 

See also a recent article by this year's Compressed Fluid Technologies award winner:

Renata Adami, Libero Sesti Osseo, Ernesto Reverchon. Micronization of lysozyme by supercritical assisted atomization. Biotechnology Bioengineering, articles on line 2009.