Particle–bubble Interaction Energies for Particles with Physical and Chemical Heterogeneities

The interaction between a particle and bubble in a liquid medium is important in processes such as mineral flotation or paper deinking. The sum of van der Waals, electrostatic, and hydrophobic interaction energies can be calculated to predict if the net interaction is favorable or unfavorable for the particle to attach to the bubble. However, conventional interaction energy calculations only relate to smooth and chemically homogeneous surfaces. Particles used in flotation have natural and induced heterogeneities such as surface roughness (SR), surface charge heterogeneity (CH), and surface contact angle heterogeneity (CAH). We therefore numerically investigated the bubble - particle interaction energy for seven hypothetical combinations of SR, CH and CAH on the particle. It was found that the strength in which the heterogeneities influence the interaction energy barrier is in the order of CAH < SR < CH. The present work is the first to provide a full theoretical view of how heterogeneities individually and in combination influence particle - bubble interactions.