Wang J, Nguyen A V
School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.
Soft Matter. 2016 Mar 28;12(12):3004-12. doi: 10.1039/c6sm00028b.
We conducted forced drainage experiments to study the liquid flow within the foams stabilized by a cationic surfactant (CTAB) in the presence of partially hydrophobic silica particles. The results show that the presence of solid particles, even when present in small amounts (0.0932 g L(-1) foam), can significantly decrease the foam permeability. The scaling behaviour (power law) between the drainage velocity and the imposed flow rate indicates that the presence of solid particles in the foams triggers a transition of the foam drainage regime from a node-dominated regime to a Plateau border-dominated regime. We applied two foam drainage equations for aqueous foams to simulate the experimental data and interpret the transition. The simulation results show that the presence of solid particles in the foams increases the rigidity of the interfaces and the viscous losses in the channels (the Plateau borders) of the foams, and decreases the foam permeability. We also generalize the theory for the effects of unattached hydrophilic particles on foam drainage by considering the effects of hydrophobicity and concentration of solid particles on the confinement of foam networks. This study explores liquid drainage in three-phase foams and is relevant to the field of hydrophobic particle separation by froth flotation, in which the wash water is commonly applied to the froth layer to improve the product grade.
我们进行了强制排水实验，以研究在部分疏水二氧化硅颗粒存在的情况下，由阳离子表面活性剂（CTAB）稳定的泡沫中的液体流动。结果表明，即使存在少量固体颗粒（0.0932 g L(-1)泡沫），也会显著降低泡沫渗透率。排水速度与施加流速之间的标度行为（幂律）表明，泡沫中固体颗粒的存在引发了泡沫排水机制从节点主导机制到 Plateau 边界主导机制的转变。我们应用了两个用于水性泡沫的泡沫排水方程来模拟实验数据并解释这种转变。模拟结果表明，泡沫中固体颗粒的存在增加了界面的刚性和泡沫通道（Plateau 边界）中的粘性损失，并降低了泡沫渗透率。我们还通过考虑固体颗粒的疏水性和浓度对泡沫网络限制的影响，推广了未附着亲水性颗粒对泡沫排水影响的理论。本研究探索了三相泡沫中的液体排水，并且与泡沫浮选疏水颗粒分离领域相关，在该领域中，通常将洗水应用于泡沫层以提高产品品位。
