Powder Micronization Using a CO2 Supercritical Antisolvent Type Process: Comparison of Different Introduction Devices

Many recrystallization processes in supercritical medium utilize CO2 as antisolvent. This work presents two introduction devices based on the principle of the supercritical antisolvent process: the impinging jets and the concentric tube antisolvent reactor. Those two processes are very simple to develop and allow improving the mixing between the two phases. Some experiments have been conducted for the impinging jets using L-polylactic acid at 10 MPa and 308 K giving spherical particles with average diameter varying from 1.4 to 2.3 mu m. For the concentric tube antisolvent reactor, griseofulvin was tested at 10 MPa and temperatures between 308 and 323 K providing needles with lengths between 25 and 50 mu m. These results combined with previous ones allow comparing these introduction devices with the classical supercritical antisolvent (SAS) process, demonstrating the following improvements: (i) reduction of particle size, (ii) increase in initial solute concentration, and (iii) process intensification.