Zhang Yongjian, Liu Chenlong, Tang Xiuxing, Dong Xin, He Tan, Wang Heyi, Zang Duyang
Shaanxi Key Laboratory of Surface Engineering and Remanufacturing, Xi'an University, Xi'an 710065, China.
School of Physical Science and Technology, Northwestern Polytechnic University, Xi'an 710129, China.
Polymers (Basel). 2022 Jul 21;14(14):2948. doi: 10.3390/polym14142948.
Bubble dynamics plays a significant role in a wide range of industrial fields, such as food, pharmacy and chemical engineering. The physicochemical properties of complex fluids can greatly affect the speed with which bubbles rise, and the lifetime of bubbles, which in turn can affect the efficiency of food and drug manufacturing and also sewage purification. Therefore, it is of great scientific and practical significance to study the influence mechanism of nanoparticles and surfactants on bubble rising and impact in a complex fluid interface. This paper selects a mixed dispersion liquid of nanoparticles (SiO) and a surfactant (SDS) as the objects of the study, observes in real-time the entire processes of bubbles rising, impact at the gas-liquid interface, and rupture, and analyzes the dynamic mechanism of bubble impact in a complex fluid interface. By analyzing the morphological changes of the rising bubbles, the rising velocity and the lifetime of the bubbles, it is found that the surfactant molecules are distributed in the ultrapure water liquid pool and the liquid film surrounding the bubbles. Such distribution can reduce the viscoelasticity between bubbles and the liquid surface, and lower the surface tension of the liquid, which can reduce the rising velocity of bubbles, delay the drainage process of bubbles on a liquid surface, and enhance the lifetime of bubbles. If the liquid surface is covered with nanoparticles, a reticulate structure will be formed on the bubble liquid film, which can inhibit bubble discharge and prolong bubble lifetime. In addition, the influence of such a reticulate structure on liquid surface tension is limited and its function is far smaller than a surfactant.
气泡动力学在食品、制药和化学工程等广泛的工业领域中发挥着重要作用。复杂流体的物理化学性质会极大地影响气泡上升的速度以及气泡的寿命，进而会影响食品和药品制造以及污水净化的效率。因此，研究纳米颗粒和表面活性剂对复杂流体界面中气泡上升及碰撞的影响机制具有重大的科学和实际意义。本文选取纳米颗粒（SiO）和表面活性剂（SDS）的混合分散液作为研究对象，实时观察气泡上升、在气液界面碰撞及破裂的全过程，并分析复杂流体界面中气泡碰撞的动力学机制。通过分析上升气泡的形态变化、上升速度和气泡寿命，发现表面活性剂分子分布在超纯水液池以及围绕气泡的液膜中。这种分布可以降低气泡与液体表面之间的粘弹性，并降低液体的表面张力，从而可以降低气泡的上升速度，延缓气泡在液体表面的排水过程，并延长气泡的寿命。如果液体表面覆盖有纳米颗粒，在气泡液膜上会形成网状结构，这可以抑制气泡排出并延长气泡寿命。此外，这种网状结构对液体表面张力的影响有限，其作用远小于表面活性剂。
