Characterization of Organic and Inorganic Chemicals Formed by Batch-Cooling Crystallization: Shape and Size

Abstract

Batch-cooling crystallization is an important industrial unit operation often carried out from aqueous solutions. Measurement of crystal size and shape plays a major role in crystallizer control in order to improve product quality. Certain crystals grown from solution may exhibit polymorphism, which can significantly affect product properties such as bioavailability as well as impinging on downstream operations such as filtration and drying. L-Glutamate was considered as a model compound for this study because it crystallizes from aqueous solution into two polymorphic forms, α and β, which are rhombic and acicular respectively. In this study, cooling rate and initial solution concentration were chosen as manipulated variables to control polymorph formation. Rapid cooling from low solution concentration favors the formation of the α form, while slow cooling with high concentration favors the β form. Oxalic acid dihydrate and copper sulfate pentahydrate, which crystallize into monoclinic and triclinic syste...