(167g) Effect of Antisolvent Purity On Antisolvent Crystallization

Antisolvent crystallization is commonly used to produce both organic and inorganic products. In antisolvent crystallization a second solvent, an antisolvent, is added to a saturated solution to induce crystallization to occur. There have been countless studies on antisolvent optimization evaluating manipulated variables such as temperature and antisolvent feedrate, but all of them neglect to investigate one important variable unique to antisolvent crystallization, antisolvent purity. The purity of the antisolvent may have a large affect on the nucleation and growth kinetics of the crystallization process. Finding an optimal purity may lead to improved crystal properties, such as mean size, reduced agglomeration, or a more monodisperse crystal size distribution. This then can be jointly optimized with the usual manipulated variables such as temperature and antisolvent feedrate to further improve crystal properties. The antisolvent system evaluated is a saturated aqueous sodium chloride solution with ethanol added as the antisolvent. It has been found that as the percentage of water in the ethanol feed increases so does the crystal mean size. This shows that changing the antisolvent purity does affect the crystal properties, and that finding an optimal antisolvent purity is beneficial.