Influence of electrolyte presence on bubble motion in solutions of sodium n-alkylsulfates (C8, C10, C12)
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J. Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences
Marcel Krzan   

J. Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
Publication date: 2012-01-01
Physicochem. Probl. Miner. Process. 2012;48(1):49–62
Influence of sodium chloride (NaCl) addition on bubble velocity in solutions of sodium n-octylsulfate (SOS), n-decylsulfate (SDS) and n-dodecylsulfate (SDDS) was studied. The NaCl concentration was varied from 0.0001 to 0.05 M. Profiles of the bubble local velocity, that is, variations of the bubble local velocity with distance from the point of the bubble formation (capillary), were determined. At low sodium n-alkylsulfates concentrations the bubbles, after the acceleration stage, reached a maximum velocity followed by a deceleration stage tending to attain their terminal velocity. The maximum disappeared at high SOS, SDS and SDDS concentrations. Electrolyte alone did not affect the bubble velocity. However, addition of even small amounts of NaCl into solutions of sodium n-alkylsulfates affected the bubble motion. The effect was especially significant at low concentrations of the surfactants studied, where the bubble terminal velocity was lowered from ca. 30-34 cm/s (no electrolyte) down to ca. 15 cm/s in 0.01M NaCl presence. The electrolyte affected the bubble motion via its influence on state of the Dynamic Adsorption Layer formed over surface of the bubbles rising in sodium n-alkylsulfates solutions.