Bubble terminal velocity has a significant effect on gas holdup, residence time, and efficiency of the interface transfer. Surfactant is often required to generate small and stable bubbles in gas-liquid two-phase devices. In this paper, bubble terminal velocities were obtained for different surfactant aqueous solutions using high-speed CCD (charged couple device) system and digital image analysis technology. Experimental results showed that available correlations were not able to accurately predict terminal velocity of bubbles rising in surfactant aqueous solutions. Thus, a new correlation is proposed based on experimental data and it provides an accurate approximation of bubble terminal velocity. The average relative error for the proposed correlation is determined to be 7.2% in MIBC aqueous solutions, 4.5% in OP-10 aqueous solutions, and 4.6% in 2-octanol aqueous solutions. The proposed correlation agrees well with experiment data from literate within ranges of the Morton number, Mo, the bubble Reynolds number, Re, and the Eotvos number, Eo: 3.29 x 10(-11)

Keywords:bubble;gas-liquid two-phase flow;surfactants;terminal velocity