A Low-Energy Emulsification Batch Mixer for Concentrated Oil-in-Water Emulsions

This work shows the formation of a high internal phase ratio oil-in-water (O/W) emulsion using a new type of a two-rod batch mixer. The mixture components have sharply different viscosities [1/3400 for water-in-oil (W/O)], similar densities (1/0.974 for W/O), and an O/W ratio of 91% (wt/wt). The simple design of this mixer leads to a low-energy process (10(6) < energy density [J m(-3)] < 10(7)), characterized by low rotational speed and laminar flow. The droplet size distribution during the emulsification was investigated according to different physical and formulation parameters such as stirring time (few minutes < t < 1 h), rotational speed (60 < Omega < 120 rpm), surfactant type (Triton X-405 and X-100), concentration (from 1 to 15.9 wt % in water), and salt addition (30 g/L). We show that all studied parameters allow a precise control of the droplet size distribution and the rheology. The resulting emulsions are unimodal and the mean droplet diameter is between 30 mu m and 8 mu m. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 27-39, 2011