SALICYLIC-ACID SOLUBILIZATION IN SUPERCRITICAL CO2 AND ITS MICRONIZATION BY RESS

Salicylic acid solubilization in supercritical CO2 and its micronization by rapid expansion of the supercritical solution (RESS) have been studied. Solubilities at 40 and 60-degrees-C in the range from 100 to 350 bar have been measured using the flow method. Experimental results have been compared with those obtained by other authors and have been successfully correlated using the Peng-Robinson equation-of-state. The influence of some process parameters on salicylic acid crystals morphology has been evaluated by analyzing the crystals precipitated in the expansion chamber by optical microscopy. Preexpansion temperature and expansion chamber temperature both have a great influence on the morphology of salicylic acid crystals. Analysis of particle-size distributions showed that the preexpansion temperature influence particle dimensions, while the temperature of the expansion chamber seemed mainly to modify the particle size distribution.