Agglomeration of Homochiral sodium chlorate crystals under near-equilibrium conditions

Abstract

This study systematically explores the agglomeration behavior of homochiral sodium chlorate crystals in turbulent flow in near equilibrium system. Sodium chlorate, known for forming optically active L- and D-enantiomers through crystallization, serves as an ideal model for examining crystal deracemization processes. The agglomeration of chiral crystals significantly impacts deracemization, as smaller crystals tend to dissolve and redeposit on larger ones. However, the formation of tightly bound agglomerates can hinder this process. This research investigates key factors influencing agglomeration, including seed crystal size, agitation speed, suspension density, and sodium chlorate solubility, using pure enantiomeric seeds. The findings reveal that smaller seed crystals rapidly agglomerate due to supersaturation fluctuations driven by the dissolution of small crystals, whereas larger seed crystals exhibit minimal agglomeration. Sodium chlorate solubility further affects agglomeration; reduced solubility decreases dissolution rates in crystal ripening, thereby limiting agglomeration. Agitation speed is critical, as increased shear stress disrupts aggregates, reducing agglomerate size. Additionally, higher suspension densities increase collision frequency and particle adhesion, enhancing agglomeration. These insights are valuable for optimizing crystallization processes, where controlling particle size and agglomerate formation is crucial, especially in industries requiring precise control over crystal properties to improve drug efficacy, filtration, and process efficiency. The study underscores the delicate balance between dissolution, growth, and breakage in agglomeration, offering a deeper understanding of how to manipulate these factors to enhance deracemization and optimize product quality in various crystallization systems.