Complete drying and micronization of ecamsule using supercritical CO2 as the antisolvent

The supercritical antisolvent (SAS) process has been used to produce micronized organic powders with excellent properties. In this study, the SAS process was used to produce fine ecamsule powder (1.8-2.8 mu m) using supercritical carbon dioxide (scCO(2)) as the antisolvent. The effects of different process parameters, such as temperature (303-333 K), pressure (10-20 MPa), ecamsule solution flow rate (0.5-2.0 mL min(-1)), and solute (ecamsule) feed concentration (2.5-10 wt%), on the process yield, particle size and size distribution, and properties of ecamsule were evaluated. To elucidate the ecamsule precipitation mechanism during the SAS process, the Hansen solubility parameters (HSPs) and relative energy differences were used to analyze the solubility of ecamsule in scCO(2)-ethanol mixtures under the studied conditions. We obtained a yield of micronsized (1.8 +/- 0.8 mu m) ecamsule particles of approximately 91% at 323 K, 14 MPa, and a solution flow rate of 1 mL min(-1) for an ecamsule feed concentration of 5 wt%. In addition, the ethanol content of the obtained ecamsule microparticles was lower than the detectable limit (< 12.5 mg L-1) and they possessed low crystalline structure with improved chemical properties compared with those of their oven-dried counterparts.