Drop breakup experiments were carried out in a stirred tank using the high-speed online camera. Breakup behaviors of drop breakup time, multiple breakage, and breakup rate were investigated. Experimental results show that the drop breakup time is mainly controlled by the interfacial tension and drop diameter, while is almost independent of the rotating speed. Besides, the dispersed phase viscosity has a slight influence on the breakup time. An empirical correlation for the breakup time is proposed and is further verified by comparing with the results of Solsvik and Jakobsen (Chem. Eng. Sci., 2015, 131: 219-234). The percentage of multiple breakage comparing to binary breakup was statistically counted. The results indicated that the dimensionless drop diameter η = d / dmax can be adopted to characterize the proportion of binary breakup. Finally, the breakup rate was experimentally measured and the breakup probability was calculated using the inverse method.

Interfacial tension is an essential physical property in two phase flow and it changes due to the mass transfer. The measurement of dynamic interfacial tension (DIFT) in such condition is a difficult problem. In previous study (Zhou at al., Chem Eng Sci. 2019; 197:172-183), we presented the quantitative relation between the droplet breakup frequency function (DBFF) and interfacial tension. It is found that the DBFF is highly depends on interfacial tension. Therefore the DBFF is a suitable parameter to quantitatively characterize the interfacial tension. Based on this concept, the DIFT in the column is determined by regression method after the DBFF under mass transfer condition is measured. It is found that the DIFT is smaller than the static interfacial tension. This result indicates that interphase mass transfer leads to decreasing of the interfacial tension. The decreasing extent of the DIFT has a positive correlation with the mass transfer flux.