Particle Formation During the Expansion of Supercritical Solutions.
Abstract
Two techniques were used to study the formation of particles from supercritical fluids. In the rapid expansion of supercritical solutions (RESS), solutes were dissolved at high pressure and precipitated by decompression across a flow restriction device. In the supercritical antisolvent process (SAS), the supercritical fluid acted as an antisolvent towards solutes dissolved in an organic-solution. RESS experiments with poly (L-lactic acid) (L-PLA) as solute showed that decreasing the density of the solvent at the exit of the expansion device caused precipitation of small and irregular L-PLA particles to occur inside the expansion device. Larger microspheres were formed at higher exit density. Encapsulation of pyrene in L-PLA microspheres was achieved by varying the initial amounts of pyrene and L-PLA present. SAS was used to make microfibers of aromatic polyamides and protein particles in the 1-5 micron size range. The protein particles retained their biological activity upon redissolution in water. The thermodynamics of mixed solute precipitation from a supercritical solution was investigated by calculating the retrograde regions of several polynuclear aromatic compounds in a supercritical solvent. The size of the retrograde region was found to decrease as the solute's heat of sublimation increased.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 27, 1996
- Accession Number
- ADA317611
Entities
People
- P. G. Debenedetti
Organizations
- Princeton University