Influence of NaCl on Granulometric Characteristics and Polymorphism in Batch-Cooling Crystallization of Glycine

The effect of NaCl added in different quantities on thermodynamic properties, granulometric characteristics, and structure of glycine in a crystallization process was investigated. Solubilities of α‐ and γ‐polymorphs in the presence of varying amounts of NaCl were analyzed. In order to examine the impact of the additive on granulometric properties of glycine, crystal morphology was examined by observing crystals under a scanning electron microscope. Crystal size distribution was determined by sieve analysis. By X‐ray diffraction analysis, the critical concentration of NaCl at which the structure of glycine changed, could be defined. The purity of obtained polymorphs was confirmed by Fourier transform infrared spectroscopy. Interactions between additives and the crystallizing phase influence crystallization processes. Batch‐cooling crystallization of glycine with different amounts of added NaCl is described, causing changes in solubility, metastable zone width, supersaturation, final mass of crystals, granulometric properties, and structure. Process conditions for a conversion of α‐ into a γ‐glycine structure are defined.