Department of Chemical Engineering, IIT Kharagpur, Kharagpur-721302, West Bengal, India.
Department of Chemical Engineering, IIT Kharagpur, Kharagpur-721302, West Bengal, India.
J Colloid Interface Sci. 2018 Oct 15;528:156-165. doi: 10.1016/j.jcis.2018.05.078. Epub 2018 May 23.
Coupled effects of hydrodynamics and chemical reaction during gelation process have been studied in the current work. Here, a viscous sodium alginate liquid drop impacts on calcium chloride liquid pool, chemically reacts with the pool, forms a crater, and instantaneously changes its phase from liquid to soft solid called as gel. The drop impingement height and liquid pool concentration are varied to study the effect on this process. This phenomenon is captured in a time resolved high-speed camera and the dynamics of the crater is traced using image processing technique. We also use a mathematical model for crater growth which we assume to be influenced by the rate of gelation. By validating the theoretical trend with the experimental counterpart, the gelation energy has been obtained. Scaling analysis has been executed to determine significant contributory energy in the crater growth. It is also observed that the gel swelling occurs beyond a critical concentration of calcium chloride. Also, the effect of gelation on the homogeneity and strength of alginate gel are interpreted from the surface morphology examination in scanning electron microscope. Thus a new insight of gelation process has been elucidated from the context of fluid dynamics.
在当前的工作中研究了凝胶过程中流体动力学和化学反应的耦合效应。在这里，粘性的海藻酸钠液滴撞击氯化钙液池，与液池发生化学反应，形成一个弹坑，并瞬间将其相态从液体变为称为凝胶的软固体。改变液滴撞击高度和液体池浓度来研究对这个过程的影响。使用时间分辨高速摄像机捕获此现象，并使用图像处理技术跟踪弹坑的动态。我们还使用了一个用于弹坑生长的数学模型，假设该模型受到凝胶化速率的影响。通过用实验结果验证理论趋势，得到了凝胶化能量。执行了标度分析以确定弹坑生长中的重要贡献能量。还观察到，在氯化钙的临界浓度以上，凝胶发生溶胀。此外，通过扫描电子显微镜对表面形貌的检查，解释了凝胶化对海藻酸钠凝胶的均一性和强度的影响。因此，从流体动力学的角度阐明了凝胶化过程的新见解。
