Electrical Properties of Silicone Oil-Water Interface in the Presence of Ionic Surfactants and Salt: Importance in the Stability of Oil-in-Water Emulsions

Silicone oil emulsions are used in a variety of industries. Electrical properties of the oil-water interface play a very important role in the stability of these emulsions. This work reports studies on the stability of silicone oil-water emulsions in the presence of ionic surfactants and salt. It was found that the addition of salt has a profound effect on the electrical properties of the interface. The kinetics of the growth of oil droplets in the emulsion was studied in emulsions containing a low volume fraction of silicone oil. The growth of droplets followed second-order kinetics commensurate with binary coalescence of droplets. It was found that the surfactant concentration and the presence of salt had a significant effect on the size of the droplets as well as their rate of growth. The stability of emulsions was correlated with the electrical properties of the oil-water interface and adsorption of surfactant molecules at the interface.