Particle formation using Supercritical Assisted Atomization technique

Supercritical Assisted Atomization (SAA) has been proposed to produce micro particles. SAA is based on the solubilisation of supercritical carbon dioxide in a liquid solution containing a solid solute. The ternary mixture is then sprayed through a thin-walled nozzle into a low pressure precipitation vessel, where warm nitrogen is also fed. Particles precipitate as a consequence of the atomization enhanced by the rapid expansion of CO2 and by the solvent evaporation induced by the nitrogen. SAA technique has been performed on different kinds of compounds, such as superconductors and catalyst precursors, organic and inorganic salts, polymers bio- polymers and pharmaceutical compounds. Also different solvents such as water, methanol, ethanol and acetone have been used. Micronic or submicronic well defined particles (in form of amorphous spheres or crystals) have been produced. The Particle Size Distributions (PSD) ranging from about 0.5 to about 5.0 μm with a relatively narrow variance have been obtained. Particle size is shown to be a function of the solute, the solvent and the operating conditions.