Zhao Yinyan, Carvajal M Teresa, Won You-Yeon, Harris Michael T
School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100, USA.
Langmuir. 2007 Dec 4;23(25):12489-96. doi: 10.1021/la701795y. Epub 2007 Nov 9.
An electrodispersion reactor has been used to prepare calcium alginate (Ca-alginate) microgel beads in this study. In the electrodispersion reactor, pulsed electric fields are utilized to atomize aqueous mixtures of sodium alginate and CaCO3 nanoparticles (dispersed phase) from a nozzle into an immiscible, insulating second liquid (continuous phase) containing a soluble organic acid. This technique combines the features of the electrohydrodynamic force driven emulsion processes and externally triggered gelations in microreactors (the droplets) ultimately to yield soft gel beads. The average particle size of the Ca-alginate gels generated by this method changed from 412 +/- 90 to 10 +/- 3 microm as the applied peak voltage was increased. A diagram depicting structural information for the Ca-alginate was constructed as a function of the concentrations of sodium alginate and CaCO3 nanoparticles. From this diagram, a critical concentration of sodium alginate required for sol-gel transformation was observed. The characteristic highly porous structure of Ca-alginate particles made by this technique appears suitable for microencapsulation applications. Finally, time scale analysis was performed for the electrodispersion processes that include reactions in the microreactor droplets to provide guidelines for the future employment of this technique. This electrodispersion reactor can be used potentially in the formation of many reaction-based microencapsulation systems.
在本研究中，已使用电分散反应器来制备海藻酸钙（Ca-藻酸盐）微凝胶珠。在电分散反应器中，利用脉冲电场将海藻酸钠和碳酸钙纳米颗粒（分散相）的水性混合物从喷嘴雾化到含有可溶性有机酸的不混溶、绝缘的第二液体（连续相）中。该技术结合了电流体动力驱动乳液过程和微反应器（液滴）中外部触发凝胶化的特点，最终产生软凝胶珠。随着施加的峰值电压增加，通过该方法生成的Ca-藻酸盐凝胶的平均粒径从412±90微米变为10±3微米。构建了一幅描绘Ca-藻酸盐结构信息与海藻酸钠和碳酸钙纳米颗粒浓度关系的图。从该图中，观察到了溶胶-凝胶转变所需的海藻酸钠临界浓度。通过该技术制备的Ca-藻酸盐颗粒具有的特征性高孔隙结构似乎适用于微囊化应用。最后，对包括微反应器液滴中反应的电分散过程进行了时间尺度分析，为该技术未来的应用提供指导。这种电分散反应器有可能用于形成许多基于反应的微囊化系统。
