高校化学工程学报Issue(1)：43-49,7.DOI:10.3969/j.issn.1003-9015.2013.01.008
初始过饱和度对谷氨酸结晶的影响研究
Effects of Initial Super-saturation on the Polymorphism and Size Distribution of Glutamic Acid
摘要
Abstract
The effect of initial glutamic acid (GA) super-saturation on GA crystallization was investigated by using monosodium glutamate (MSG) solution to replace GA fermentation broth under pH-shift operation mode. The results show that the super-saturation degree of the solution influences both crystal habit and crystal size distribution (CSD). The crystal habit is mainly in α-form and CSD exhibits a symmetric distribution with logarithmic form when super-saturation degree (S) is below 7.15 (S≤7.15). With the increase of super-saturation degree, theβ-form crystal percentage increases and medium size crystallization decreases but with a wider CSD. When S exceedes 14.17 (S≥14.17), all of the crystal habit are in β-form, and CSD becomes dispersive and irregular. Based on the classical nucleation theory, the GA polymorphism nucleation rates under different super-saturation degrees and MSG concentrations are calculated, and the results demonstrates that the polymorphism nucleation rates both increase with the increases of super-saturation degree and MSG concentration. The α-form crystal nucleation rate is faster than that of β-form at the same super-saturation degree, whileβ-form crystal nucleation rate is faster than that ofα-form at the same MSG concentration. The results suggest that the major reason accounting for CSD of glutamic acid is due to the nucleation rate increases with the increase of super-saturation degree, while the crystal habit mainly depends on the difference of the two competitive nucleation rates. A C-pH phase diagram model forα-andβ-GA crystals was proposed based on the existing reports and the results obtained in this study, and this model could theoretically interpret the mechanism of super-saturation degree affecting GA crystal habit.关键词
谷氨酸/结晶/过饱和度/晶习/粒度分布Key words
glutamic acid/crystal/supersaturation/polymorphism/crystal size distribuition分类
化学化工引用本文复制引用
张建华,曹付明,张宏建,唐蕾,毛忠贵..初始过饱和度对谷氨酸结晶的影响研究[J].高校化学工程学报,2013,(1):43-49,7.基金项目
国家863高技术研究与发展计划项目(2006AA020303-02) （2006AA020303-02）
