Coalescence of air bubbles: Effect of the electrical double layer

Abstract

This research studied the effect of collectors and frothers on the double electric layer (specifically, the zeta potential) and on the time for the coalescence of bubbles. The collectors studied were potassium ethylic xanthate (anionic) and dodecylamine (cationic), and the studied frother was terpineol. The time of coalescence was considered as the time elapsed since the bubble had contact with the air–liquid interface at the level of liquid contained in the cell until the time in which it collapsed with it. Each test was repeated at least 10 times to obtain a database of 418 tests. It was concluded that, without considering the surface effect, the coalescence time increases, increasing the electrical conductivity of the aqueous solution, and that the zeta potential of the bubbles affects the coalescence time with a non-linearly form; this effect has not yet been addressed in the literature.