原子間力顕微鏡による水溶液中での固体微粒子‐気泡間相互作用力の直接測定

Abstract

Interaction forces between a bubble and a particle are critical for various industrial processes that handle colloidal dispersions, especially for froth flotation. Therefore, it is fundamentally important to understand the surface force between a bubble and a particle to control froth flotation process effectively. In this study, we conducted direct measurements of interaction forces between a spherical solid particle (silica and iron oxide) and a small air bubble in aqueous electrolyte using atomic force microscope (AFM). Interaction forces were measured between the particle attached on the top of AFM probe and air bubble generated on the flat surface. The forces between the silica and the bubble were repulsive over the wide range of the conditions of present experiments. The origin of the force was considered to be electrostatic force. In the case of iron oxide-air bubble system, the interaction forces were attractive when the pH was lower than isoelectric point (iep) of the ion oxide, while the forces were repulsive when the pH exceeded the iep. The attractive forces were stronger and longer-ranged than the force predicted by heterocoagulation theory. It was found that these interaction forces could explain batch column flotation results with nitrogen gas bubbles qualitatively.