Effects of Surface Activities of Extractants on Drop Coalescence and Breakage in a Mixer-Settler

Abstract

This work focuses on the relationship between surface activities of extractants and drop coalescence and breakage. Drop size distribution and Sauter mean diameter have been measured in one stage of a mixer-settler extraction column for three different liquid-liquid systems as functions of flow rate of dispersed phase, agitation speed, and concentration of extractants. Effects of drop coalescence on drop size have been investigated for three different types of extractants. The results show that the difficulty in occurrence of drop coalescence greatly influences the drop distribution pattern. The Sauter mean diameter for these three extractant systems increases linearly with the holdup of dispersed phase in the mixer and slopes of lines for these three systems are similar. Extractants have the ability to inhibit or promote drop coalescence by their surface activities. For coalescence inhibitors the data of drop size plotted versus interfacial tension fall on the same line, while the drop size measured for coalescence promoter is larger than the line.