Time evolution of the drop size distribution for liquid–liquid dispersion in an agitated tank

Agitating two immiscible liquids or a solid–liquid suspension is an operation frequently performed in the chemical and metallurgical industries, for example, in suspension/emulsion polymerization, heterogeneous/phase-transfer catalytic chemical reactions, and hydrometallurgical solvent extraction. For emulsification, suspension polymerization, solid particle dispersion, and crystallization, it is essential to be able to predict the mean drop/particle size and the drop/particle size distribution. A simple model was proposed for predicting the time evolution of drop size distribution during drop breaking, and was successfully tested on data published by Ruiz and Padilla (Hydrometallurgy 72:245–258, 2004) and by Sathyagal et al. (Chem Eng Sci 51: 1377–1391, 1996) and on our own data. The time evolution of DSD was investigated in a baffled tank agitated by a Rushton turbine for a liquid–liquid dispersion. The tests were carried out on a silicone oil–water dispersion (oil in water) with a dispersed-phase fraction of 0.00047. The drop sizes were determined by image analysis.