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Investigation of spontaneous emulsification and its relevance in biodiesel synthesis†
Reaction Chemistry & Engineering ( IF 3.9 ) Pub Date : 2018-03-14 00:00:00 , DOI: 10.1039/c7re00205j
Rohidas Bhoi 1, 2, 3, 4 , Sanjay Mahajani 1, 2, 3, 4
Affiliation  

Transesterification of triglycerides (TGs) is associated with the coexistence of two sparingly miscible liquid phases. In this study, the reaction is carried out in a batch reactor with independent stirring of both the phases by maintaining a flat interface. An initial delay period followed by a sudden rise in reaction rate is observed. The S-shaped TG conversion curve thus represents an in situ change in the rate-controlling step during the course of reaction. The intrinsic reaction is reasonably fast and the progress of the reaction, in the initial period, is strongly influenced by the speed of agitation and the interfacial area. A spontaneous emulsion is observed as the reaction proceeds, resulting in a sudden rise in the interfacial area, and hence, the reaction rate. We observed that the change in the compositions of the individual phases was responsible for a decrease in the interfacial tension. At a particular concentration of the individual phases, a spontaneous emulsion is realized, beyond which, the reaction becomes kinetically controlled. During this period, the reaction rate is independent of agitation speed. The experimental results in both the pre- and post-emulsion period are explained using an appropriate model. We demonstrate that an appropriate selection of the initial composition of the two phases in a conventional batch reactor can conveniently eliminate the initial delay due to diffusional limitations.

中文翻译:

自发乳化及其在生物柴油合成中的相关性研究

甘油三酸酯(TGs)的酯交换反应与两种难混溶的液相共存有关。在这项研究中,反应是在间歇式反应器中进行的,并且通过保持平坦的界面独立搅拌两相。观察到初始延迟期,随后反应速率突然升高。因此,S形TG转换曲线代表原位反应过程中速率控制步骤的变化。固有反应相当​​快,并且在开始阶段,反应的进行受到搅拌速度和界面面积的强烈影响。随着反应的进行,观察到自发的乳液,导致界面面积突然增加,因此反应速率增加。我们观察到,各相组成的变化是界面张力降低的原因。在各个相的特定浓度下,实现了自发的乳液,超过此范围,反应就变成了动力学控制的。在此期间,反应速率与搅拌速度无关。使用合适的模型解释了乳化前后的实验结果。
更新日期:2018-03-14
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