Crystallization of glycine with ultrasound.

Sonocrystallization has proved to be an efficient tool to influence the external appearance and structure of a crystalline product obtained by various crystallization methods. The present work focuses on high intensity sonocrystallization of glycine by varying amplitude of ultrasound with an ultrasound frequency of 20kHz at two temperature ranges 40-50 and 20-30 degrees C in a jacketed 250-ml cooling crystallizer equipped with a stirrer. The polymorph composition of the obtained crystals was analyzed with a temperature variable X-ray powder diffractometer (XRPD). XRPD results showed that, besides the operating temperature, the glycine polymorphism was affected also by insonation. This was especially the case at the lower temperature range. Furthermore, based on the heat balance within the crystallizer, an increase in required cooling capacity was presented as a function of increasing ultrasound power. This study also showed, the higher the ultrasound amplitude the smaller the crystals obtained.