Analysis of water entrainment into dispersed w/o emulsion drops

Abstract

The effects of operating conditions on mechanical water entrainment into W/O emulsion drops in a (W/0)/W emulsion system were studied in a stirred tank in the absence of permeation due to osmotic pressure. The water entrainment was influenced by surfactant concentration, water volume fraction in W/O emulsion, inner water drop size, salt concentration in the external water phase, and agitation speed in the stirred tank. There was a satisfactory correlation between the extent of water entrainment and the weight of surfactant per unit interfacial area. These observations suggested that water entrainment proceeded as a result of additional emulsification at the drop surface. This idea was confirmed by examining the water entrainment in an oilwater dispersion system where water entrainment occurred by emulsification. The effects of the operating conditions on water entrainment in the oilwater dispersion system were quite similar to those in the (W/0)/W emulsion system. In addition, the volume of water entrained per unit surface area of dispersed oil drops was in fair agreement with that in the (W/0)/W emulsion system. These results supported the proposed mechanism of water entrainment. © 1988, The Society of Chemical Engineers, Japan. All rights reserved.