Supercritical fluids-assisted micronization techniques. Low-impact
routes for particle production*
Ernesto Reverchon and Giovanna Della Porta
Dipartimento di Ingegneria Chimica e Alimentare, Università
di Salerno, Via Ponte Don Melillo, 84084, Fisciano (SA), Italy
Abstract: Micronized powders are of interest in many industrial
fields; pharmaceuticals, catalysts, pigments, and biopolymers, for example,
are some categories of products that can be used as micro-sized particles.
Traditional techniques used to produce micronic powders are based on
high-temperature reactions that require high energies, on jet milling
that is characterized by low efficiencies and mechanical stress, and
on liquid solvents precipitation that has a poor control on particle
size and can pollute the product. Generally, the control of the powder
size and the span of its distribution are still very approximate.
In the last few years, several supercritical fluids-based techniques
have been proposed for the production of micronic and nanometric particles.
These processes try to take advantage of some specific properties of
gases at supercritical conditions such as enhanced solubilization power
and its modulation, large diffusivities, solventless or organic solvent
reduced operation, and the connected possibility of controlling powder
size and distribution. Techniques like the rapid expansion of supercritical
solutions (RESS), supercritical antisolvent precipitation (SAS), particle
generation from gas-saturated solutions (PGSS), and new atomization
processes have been critically reviewed in this work.
*Lecture presented at the IUPAC CHEMRAWN
XIV Conference on Green Chemistry:Toward Environmentally Benign Processes
and Products, Boulder,Colorado, USA, 9-13 June 2001. Other presentations
are published in this issue, pp.1229 –1330.
