Bubble coalescence behavior in pure and contaminated liquid

Abstract

The bubble coalescence phenomena were investigated in a bubble contacting device, and the bubble properties (bubble size, bubble size distribution, bubble rising velocity) have been studied in a 0.1 m ID plexiglas column. For a study of the coalescence of pair of bubbles, the bubble coalescence time and coalescence percentage have been determined with the variation of bubble forming frequency (0.23-2.3 m/s) and solutes (n-alcohols, sodium lauryl sulfate, KCl and $K_2SO_4$), and the distance between two tips of orifice (No. 14 gauge stainless needle) was fixed as 0.85 mm. Surface tensions of raw materials were measured by a forming bubble method In a bubble column study, the effects of superficial gas velocity (0.011 m/s-0.05 m/s) and concentration of electrolytes (KCl, $0.1-0.3 kmol/㎥$, $K_2SO_4$, $0.02-0.1 kmol/㎥$) on gas phase holdups and bubble properties have been determined by a resistivity probe. The obtained experimental and theoretical results can be summarized as follows: It was found that forming bubble method was useful for measuring surface tension of liquid or solution, also the effect of the bubble forming frequency on the measured surface tension were investigated in n-alcohols and sodium lauryl sulfate. The bubble diameter could be treated as uniform when the nozzle diameter was about 1 mm or less. And as Tate``s law was good for static, the bubble forming frequency should be maintained in order to hold the quasi-static balance. In a bubble contacting device, observation of the coalescence processes of gas bubbles were carried through optical sensing method. This method showed a reliable reproducibility for studying the behavior of bubble coalescence. Surface active solutes which gave large surface elasticity had the effect of retarding the coalescence of gas bubbles. The effect of bubble forming frequency on bubble coalescence percentage was shown opposite tendency with the species of solute. For low molecular alcohols such as 1-butanol and n-a...