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 emul sions) have been induced by changes in the phase ratio. Drop size dist ribution during catastrophic phase inversion was found to depend on st irring speed and on the addition rate of the aqueous phase. The format ion of oil-in-water-in-oil drops and the choice of surfactant are impo rtant. A wide range of phase ratios was used in the experiments and ch anges in drop sizes (and in drop size distributions) were determined t hroughout the phase inversion. A number of different drop formation me chanisms which are compatible with the experimental results are propos ed. Quantitative relationships between drop sizes, stirrer speed and p hase ratio are obtained for a wide range of phase ratios. Coalescence mechanisms are related to energy balances for the dispersions. Drop si zes in the inverted emulsions are compared with sizes which can be obt ained by direct emulsification. Smaller drops are produced by direct e mulsification because drop coalescence is less important than is the c ase with catastropic inversion.