| The role of electrostatic properties and particle shape on toner flotation is investigated. Toner electrostatic properties, as measured by the zeta potential, are found to have little correlation on floatability due to the strong hydrophobicity of the toner surface. Flotation experiments in a Hallimond tube and in a single bubble flotation tube show that model toner spheres and are more readily floated than similar volume disks. High-speed motion pictures of particle/bubble interactions in a flowtube show differences in disk and sphere behavior. Spheres are deflected away from the bubble by flow but usually attach if they contact the bubble surface. Disks often collide with the bubble edge-on but immediately bounce off, seldom attaching to the bubble due to the very short contact time. Alternatively, disks (particularly small disk fragments) turn to the side as they approach the bubble but seldom attach due to a large thin-film drainage area.;To describe the motion of large disks around a bubble, a simple hydrodynamic model is constructed and used to conduct a parametric study of the effect of disk size and initial orientation on the efficiency of collision,... |
