Bubble collisions with hydrophobic and hydrophilic surfaces in alpha-terpineol solutions
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Institute of Catalysis and Surface Chemistry Polish Academy of Sciences
Kazimierz Malysa   

Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
Publication date: 2003-01-01
Physicochem. Probl. Miner. Process. 2003;37(1):37–50
Influence of α-terpineol on phenomena occurring when a gas bubble approaches (collides with) hydrophilic (glass) and hydrophobic (Teflon) solid surfaces was revealed using high-speed camera (1182 frames/s). It was found that the bubble approaching the solid surface bounced backwards from the surface and its shape pulsated rapidly with frequency over 1000Hz. Number of the bouncing cycles and magnitude of the shape pulsations were decreasing with increasing α-terpineol concentrations. In distilled water the amplitude, frequency and number of the “approach-bouncing” cycles were identical at Teflon and glass interface. In of α-terpineol solutions a “necking” formation was recorded at Teflon surface, but not at the glass. The “necking” formation is a straightforward indication that the three- phase contact was formed. We found the most intriguing that a small amount of α-terpineol (adsorption coverage of 0.6%) sped-up and affected in such significant degree the bubble attachment to the hydrophobic surface. It was found that the induction time of the bubble attachment to Teflon was 5 milliseconds in α-terpineol presence. The average thickness of the thin liquid film separating the bubble and Teflon was estimated to be ca. 2,7 μm at the film rupture.