Study on bubble penetrating solution/frother interface in the presence of ions

The drainage and rupture of solution/frother interface is a prerequisite to predict the adsorption of frother onto the bubble surface. Using a high-speed motion acquisition system, we investigated the dynamic penetration of bubble at the solution/frother interface under four factors that height, capillary inner diameter, ion concentration and ionic valence. Since the kinetic energy of bubble was proportional to the radius and rising velocity, the kinetic energy increased with increasing the height and capillary inner diameter while decreased with increasing the ion concentration and ionic valence. The variation of kinetic energy followed the order: capillary inner diameter > ion concentration > height > ionic valence. The drainage time of the bubble at the solution/frother interface was found to decrease as the kinetic energy increased independently of these factors, indicating that the rupture of the hydration film was significantly influenced by the kinetic energy. A solution column caused by the bubble penetrating the solution/frother interface was observed. The column height increased as the kinetic energy increased for the factors of height and capillary while an opposite trend was presented by the factors of ion concentration and ionic valence. IFT was discussed to be the essential reason for the difference in the penetration. IFT of the solution/air interface increased as the ion concentration increased independently of ion species, and the IFT of different interfaces followed the order: solution/air > frother/air > solution/frother. Our results can provide valuable insight into the development of technology for surfactant adsorption and mineral flotation .