On The Mechanism Of The Action Of Frothers In The Colliding Bubble Attachment To Hydrophobic Surfaces Of Different Roughness

Influence of frothers (a-terpineol and n-octanol) concentration on kinetics of a three phase contact (TPC) formation by a bubble colliding with a hydrophobic surface (Teflon) of different roughness was studied using a high-speed camera (1040 frames per second). It was found that the Teflon surface roughness and the frother concentration strongly affected time of the TPC formation (tTPC) and time of drainage (tD) of the liquid film separating the colliding bubble from the solid surfaces. With increasing Teflon surface roughness, from ca 1 to 80 µm, the time of the TPC formation was shortened by over the order of magnitude, from ca 100 to a few milliseconds only. At low a-terpineol and n-octanol concentrations, thetTPC values were shorter than in distilled water due to lowering the bubble velocity in the frother presence and diminished bouncing of the colliding bubble. However, at high frothers concentrations the tTPC values were prolonged, despite that the bubble velocity was similar. The prolongation of the tTPC at high frother concentrations indicates that air (micro- and/or nano-bubbles) was present at the Teflon surfaces of different roughness. The mechanism of the tTPCprolongation at high frother dosage is described.