Crystalline microparticles of controlled size produced by supercritical-assisted atomizatione

Supercritical-assisted atomization (SAA) is a promising technique that can be used to produce micron- and submicron-sized particles of several kinds of compounds using water or organic solutions. It is based on the solubilization of supercritical CO2 in the liquid solution formed by the solvent and the (solid) solute and on the subsequent atomization of this solution using a thin-walled nozzle. In this work, supercritical-assisted atomization operated at pressures below 12 MPa and at temperatures between 65 and 95 degreesC has been applied to sodium chloride, potassium iodide, and ammonium chloride to test the possibility of producing microcrystals of controlled dimension. The influence of the concentration of the liquid solution was investigated. Cubic crystals were obtained for two of the tested materials; crystalline particles were also produced in the case of ammonium chloride. A mechanism for crystal formation during SAA at different concentrations is proposed.