School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China; The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Tianjin 300072, China.
School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China; The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Tianjin 300072, China.
Ultrason Sonochem. 2020 Nov;68:105227. doi: 10.1016/j.ultsonch.2020.105227. Epub 2020 Jun 16.
In this paper, the crystallization of L-glutamic acid with application of ultrasound was explored in detail, including the process of nucleation, polymorphic control and polymorphic transformation. The induction time and metastable zone widths (MSZWs) were measured with and without ultrasound during the nucleation process. The induction time and MSZWs were decreased by ultrasound and the induction time was further decreased by higher ultrasonic power. The calculated nucleation parameters (such as interfacial energy, critical nucleus size and critical Gibbs energy) showed an obvious decrease in the presence of ultrasound, indicating that the nucleation was enhanced with application of ultrasound. By adjusting the ultrasonic power in the quench cooling process, the difference in nucleation temperatures would determine the distribution of polymorphs. In further, the polymorphic transformation was investigated quantitatively, and to the best of our knowledge, it was the first time to study the transformation kinetics with ultrasound using Avrami-Erofeev model. In the transformation process, the crystallization mechanism of the stable form was modified by ultrasound. The ultrasound eliminated the nucleation element in the rate-limiting step and facilitated the crystal growth of stable form. Thus, the ultrasound has a profound influence on L-glutamic acid crystallization.
本文详细探讨了应用超声技术促进 L-谷氨酸的结晶过程，包括成核过程、多晶型控制和多晶型转变。在成核过程中测量了有无超声作用时的诱导时间和亚稳区宽度（MSZW）。超声作用降低了诱导时间和 MSZW，并且较高的超声功率进一步降低了诱导时间。计算的成核参数（如界面能、临界核大小和临界吉布斯自由能）在超声存在下明显降低，表明超声促进了成核。通过在猝冷过程中调整超声功率，可以根据成核温度的差异来确定多晶型的分布。进一步定量研究了多晶型转变，据我们所知，这是首次使用 Avrami-Erofeev 模型研究超声作用下的转变动力学。在转变过程中，超声改变了稳定型的结晶机制。超声消除了限速步骤中的成核单元，并促进了稳定型晶体的生长。因此，超声对 L-谷氨酸结晶有深远的影响。
