PHASE INVERSION IN NONIONIC SURFACTANT OIL-WATER SYSTEMS .2. DROP SIZE STUDIES IN CATASTROPHIC INVERSION WITH TURBULENT MIXING

In agitated liquid-liquid dispersions, catastrophic phase inversions (in which water-in-oil emulsions are transformed into oil-in-water emulsions) have been induced by changes in the phase ratio. Drop size distribution during catastrophic phase inversion was found to depend on stirring speed and on the addition rate of the aqueous phase. The formation of oil-in-water-in-oil drops and the choice of surfactant are important. A wide range of phase ratios was used in the experiments and changes in drop sizes (and in drop size distributions) were determined throughout the phase inversion. A number of different drop formation mechanisms which are compatible with the experimental results are proposed. Quantitative relationships between drop sizes, stirrer speed and phase ratio are obtained for a wide range of phase ratios. Coalescence mechanisms are related to energy balances for the dispersions. Drop sizes in the inverted emulsions are compared with sizes which can be obtained by direct emulsification. Smaller drops are produced by direct emulsification because drop coalescence is less important than is the case with catastropic inversion.