Effects of Surfactant on Bubble Size Distribution and Gas Hold-up in a Bubble Column

Abstract

This study investigates the influence of two surfactants –a non-ionic (Tween20) and a zwitterionic (Cocoamidopropyl Betaine) – upon the gas-liquid hydrodynamics in a bubble column. These kinds of substances can have an important influence upon the gas-liquid hydrodynamics, specifically on the bubble size and gas hold-up. Bubble diameters were measured photographically in a bubble column, which was operating in the homogeneous regime with air and aqueous surfactant solutions. The bubble size and gas hold-up data were determined for several values of the superficial gas velocity (0.13, 0.26 and 0.5 cm/s). On the other hand, bubble diameter was determined for different values of surfactant concentration (0.02, 0.05 and 0.1 %vol). At superficial gas velocity below 0.26 cm/s, addition of surfactant in air-water has low influence on bubble size, whereas higher gas velocity addition of surfactant increases the number of bubble. In surfactant solutions (in comparison with pour water), resulted in an increase in number of bubble and a rough decrease in Sauter mean bubble diameter. Bubbles tend to become smaller with decreasing surface tension of water. Therefore, surfactant existence increases the gas hold-up. Further, gas holdup increased when gas bubbles movement increased.