超声波对甘氨酸溶析结晶过程的影响

Effect of Ultrasound on Anti-solvent Crystallization Process of Glycin

以甘氨酸水溶液的丙酮溶析结晶为对象,探讨了超声波对结晶过程的影响.在超声波作用下,结晶过程经历空泡形成、超声波诱导成核、二次成核多个阶段;在不同的阶段施加超声波,或在相同时刻引入超声波但持续不同的时间,都可能影响晶体的粒径大小和分布.在自然均相成核点之前施加超声波并持续较短时间,使晶核以超声波诱导成核为主时,可获得较大颗粒的晶体;在接近均相成核点处施加超声波,将产生更多的晶核,使晶体平均粒径降低.在晶体生长过程中继续使用超声波,因超声波的破碎效应,也将降低晶体的平均粒径.

Crystallization of aqueous glycin solution with acetone as the anti-solvent is studied to examine the effects of ultrasound on crystal size and habit. With ultrasound excitations, the solution experiences cavitation, first nucleation, second nucleation, crystal growth, fragmentation, etc. Introducing ultrasound at different times or for different durations will have different influences on the crystallization distribution. If ultrasound is introduced for a short time before the onset of homogeneous nucleation to induce nucleation, one will obtain larger crystals, whereas if the ultrasound is introduced at or after the onset of homogeneous nucleation, smaller crystals will be obtained. If ultrasound is used in the growth stage, the crystals will also be small because the crystals will be fragmented by ultrasound.