Experimental measurement and modeling of dynamic interfacial tension in a stirred tank

Abstract In liquid–liquid extraction processes, to obtain droplet size distribution that affects mass transfer, precisely characterizing droplet behaviors, such as breakage and coalescence, is necessary. However, mass transfer can also affect droplet breakage through its influence on interfacial tension, which is known as dynamic interfacial tension (DIFT) in mass transfer conditions. Therefore, it is important to reveal the relation between DIFT and mass transfer. In this study, a method based on a breakage model is developed to measure the DIFT in a stirred tank, and the mass transfer process is analyzed based on single droplet dispersion. It is found that the DIFT increases with the increasing impeller rotating speed or the decreasing solute concentration. The effect of residence time on the DIFT is not obvious. Among these factors, the DIFT is mainly determined by the solute concentration on the interface, and a model predicting the DIFT is established.