Lekhal A, Girard K P, Brown M A, Kiang S, Khinast J G, Glasser B J
Department of Chemical and Biochemical Engineering, Rutgers University, Piscataway, NJ 08854, USA.
Int J Pharm. 2004 Feb 11;270(1-2):263-77. doi: 10.1016/j.ijpharm.2003.10.022.
Experiments have been carried out to study the behavior of L-threonine (needle-like) crystals during agitated drying. For an L-threonine/water system the morphology of the crystals was monitored using light microscopy and image analysis. Analysis of the transient behavior of the crystal size and shape distribution showed that attrition and agglomeration took place simultaneously during the process. The variation of the operating conditions (temperature, agitation and vacuum) revealed that attrition dominated the drying process when the drying rate was low and/or the shear rate was high. For high drying rates and low shear rates, agglomeration became dominant. This study suggests that crystal redissolution had no significant impact on crystal morphology. It was also found that due to their needle-like shape, large L-threonine crystals were very sensitive to attrition. When attrition controlled the drying process, most of the particle size reduction took place below a critical moisture content of 4%. When agglomeration controlled the drying process, most of the crystal size enlargement occurred below a moisture content of 6%.
已开展实验研究L-苏氨酸（针状）晶体在搅拌干燥过程中的行为。对于L-苏氨酸/水体系，使用光学显微镜和图像分析监测晶体的形态。对晶体尺寸和形状分布的瞬态行为分析表明，在此过程中磨损和团聚同时发生。操作条件（温度、搅拌和真空）的变化表明，当干燥速率较低和/或剪切速率较高时，磨损主导干燥过程。对于高干燥速率和低剪切速率，团聚变得占主导地位。该研究表明，晶体再溶解对晶体形态没有显著影响。还发现，由于其针状形状，大的L-苏氨酸晶体对磨损非常敏感。当磨损控制干燥过程时，大部分粒径减小发生在临界水分含量4%以下。当团聚控制干燥过程时，大部分晶体尺寸增大发生在水分含量6%以下。
