Passive acoustic emission monitoring to detect bubble coalescence in the presence of solid particles

Passive acoustic emission monitoring was used to study the role of solid particles on bubble coalescence. The effect of 1-10% w/w talc (hydrophobic) or silica (hydrophilic) particles on air bubble formation and coalescence at a capillary in the presence of MIBC or sodium chloride was determined. Both solids slightly inhibited bubble coalescence while silica created a larger region of partial coalescence compared to talc. At 10% w/w the silica particles appeared to promote coalescence at high MIBC concentration.