Effect of Initial Supersaturation on Mechanism of Purity Drop during Preferential Crystallization

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN

Akihiko Ito¹  Masakuni Matsuoka¹ 

[1] Department of Chemical Engineering, Tokyo University of Agriculture and Technology

关键词: Preferential Crystallization;    DL-Threonine;    Initial Supersaturation;    Purity Drop;   

DOI  :  10.1252/jcej.07we279

来源: Maruzen Company Ltd

【 摘 要 】

References(10)Cited-By(2)In order to understand the effect of initial supersaturation on the mechanism of purity drop during preferential crystallization, two sets of experiments were carried out with a threonine-water system. One set was the observation of the {210} faces of L-Thr seed crystals placed in solutions at various supersaturation levels of D-Thr, and the other was preferential crystallization on the basis of the observation results. From the observation, needle-like D-Thr crystals, which nucleated in the bulk solution, were observed in supersaturated DL-Thr solutions at supersaturation of D-Thr (σD) below 0.19, while thin plate-like D-Thr crystals were found to appear on the {210} faces when σD was above 0.21. During preferential crystallization for the solution of initial supersaturation of σi = 0.16, needle-like crystals nucleated in the bulk solution were observed and the bulk nucleation of D-Thr was the mechanism of the purity drop. On the contrary, when the initial supersaturation σi was 0.21, thin plate-like D-Thr crystals were found to appear by surface nucleation. The surface nucleation of D-Thr was the mechanism of the purity drop. On the basis of observations and preferential crystallization, the mechanisms of the purity drop were concluded to be dependent on the σi in solutions.

【 授权许可】

Unknown