Investigation the Nucleation Process in Rapid Expansion of Supercritical Solution (RESS) Process

When a supercritical solution is rapidly expanded, large solute supersaturation can be attained, and small particles are formed. The evolution of the homogeneous nucleation rate, work of nucleus formation, and critical nucleus size along different expansion paths is investigated here for the model system benzoic acid-carbon dioxide. Nucleation rates are the result of the competition among solvent expansion, cooling due to depressurization, and high supersaturation. Although supersaturation can reach very high values ( 106), relatively flat nucleation rate profiles result due to cooling and expansion.