上升气泡与塑料平板在纯水中的碰撞黏附行为

为了揭示气泡尺寸和表面疏水性对塑料浮选过程的影响规律，采用高速摄影技术观测上升气泡与塑料平板在纯水介质中的碰撞黏附行为。根据气泡速率的变化情况，将碰撞黏附行为细分为碰撞、液膜排液、三相接触线扩散等3个阶段，基于图像处理技术定量分析了气泡碰撞形变、黏附时间、三相接触线扩散特性及其影响因素。结果表明:变形因子随气泡直径的增大由略大于1.00逐渐演化为略小于1.00，疏水性强的塑料平板使相同直径气泡的变形因子更大，碰撞时间随气泡直径的增大而增加，随疏水性的增加而减小。塑料平板疏水性越强，形成三相接触所用时间越短，当气泡直径为1.0 mm时，聚四氟乙烯（PTFE）和聚甲基丙烯酸甲酯（PMMA）平板的液膜排液时间均出现极小值，分别为4.8 ms和56 ms。三相接触线扩散时间随气泡直径的增大而增大，随塑料平板疏水性的增大而减小，在气泡直径大小相同时，三相接触线扩散直径随塑料平板疏水性的减小而减小。 

Collision and attachment behavior between rising bubble and plastic plate in pure water

In order to reveal the influence of bubble size and surface hydrophobicity on the flotation process of plastics, high-speed photography was used to observe the collision and adhesion behavior of rising bubbles and plastic plates in pure water medium. According to the change of bubble velocity, it is divided into three stages:collision, liquid film drainage and three-phase contact line diffusion. Based on image processing technology, the bubble collision deformation, adhesion time, three-phase contact line diffusion characteristics and their effects are quantitatively analyzed. The results show that the deformation factor gradually evolves from slightly larger than 1.00 to slightly less than 1.00 as the diameter of the bubble increases. The hydrophobic plate with strong hydrophobicity makes the deformation factor of the same diameter bubble larger, and the collision time increases with the increase of the bubble diameter, but decreases with the increase of the hydrophobicity. The stronger the hydrophobicity of the plastic plate is, the shorter the time it takes to form a three-phase contact. When the bubble diameter is 1.0mm, the liquid film discharge time of both the poly tetra fluoroethylene (PTFE) and polymethyl methacrylate (PMMA) plates is extremely small, which are 4.8 ms and 56 ms respectively. The diffusion time of the three-phase contact line increases with the increase of the bubble size, and decreases with the increase of the hydrophobicity of the plate. When the bubble size is the same, the diffusion diameter of the three-phase contact line decreases as the hydrophobicity of the plate decreases.