Kinetics in directional drying of water that contains deformable non-volatile oil droplets
Kinetics in directional drying of water that contains deformable non-volatile oil droplets
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DOI：
10.1039/c7sm01490b
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发表时间：
2017-10-21
期刊：
影响因子：
3.4
通讯作者：
Inasawa, S.
中科院分区：
文献类型：
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作者：
Hasegawa, K.;Inasawa, S.
在这里，我们报告了基于共聚焦显微镜的直接观察，对含有非挥发性油滴的水的定向干燥动力学的评估。在干燥的初始阶段，水分以恒定的速度蒸发，之后蒸发速度下降。当周围的水丢失时，分散的油滴被压缩和扭曲。水的进一步蒸发导致油滴的合并，最终在干燥界面形成油层。然而，很明显，干燥速度甚至在油层形成之前就已经降低了。我们认为，通过扭曲的油滴之间狭窄的路径限制了水的传输是导致干燥速度降低的原因。建立了基于泡沫排水理论的数学模型，较好地描述了实验数据。这项工作还确定了油滴的临界分离压力受干燥速度的影响，因此较高的压力值与较慢的干燥条件有关。讨论了分散油滴的干燥动力学和稳定性。
Herein, we report assessments of the kinetics in directional drying of water that contains non-volatile oil droplets, based on direct observations using a confocal microscope. The water was found to evaporate at a constant rate during the initial stage of drying, after which the evaporation rate decreased. The dispersed oil droplets were compressed and distorted as the surrounding water was lost. Further evaporation of water resulted in coalescence of the oil droplets, with the eventual formation of an oil layer at the drying interface. However, it was apparent that the drying rate decreased even before the formation of this oil layer. We propose that the restricted transport of water via the narrow paths between the distorted oil droplets was responsible for the decreased drying rate. A mathematical model based on foam drainage theory is proposed and describes the experimental data very well. This work also determined that the critical disjoining pressure for the oil droplets is affected by the drying rate, such that higher pressure values are associated with slow drying conditions. The drying kinetics and stability of the dispersed oil droplets are discussed.