Lookup NU author(s): Dr Jonathan Lee
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The presence of a non-ionic surfactant (Brij 92) is seen to have a significant effect on the rate of coalescence of a water-in-oil dispersion subjected to a pulsed DC electric field. This effect is studied using water drops dispersed in a silicone-based solvent (Volasil 245TM) in a twin cell apparatus. The rate of separation is measured in one cell with surfactant present and compared to a control cell without surfactant. The intensity of light transmitted through the test cells gave an indication of the degree of coalescence in the dispersion. The effect of pulse frequency and of coating the positive electrode are investigated. It is found that when the positive electrode coating is present, the rate of separation increases with increasing pulse frequency in a system with 0.1% vol surfactant. The authors have previously shown that the electrophoretic force on drops in a water-in-oil dispersion contributes to the enhanced rate of coalescence. With insulation coating and surfactant present it is shown that the drops maintain their charge yet do not undergo electrophoretic motion. Therefore it is concluded that the presence of surfactant must lead to a decrease in the electric field acting on the dispersion. A better separation rate is observed without surfactant, but as most water-in-oil emulsions encountered in crude oil treatment contain surfactants, observations of this nature are important.
Author(s): Bailes PJ, Lee JGM, Parsons AR
Publication type: Conference Proceedings (inc. Abstract)
Conference Name: World Congress of Chemical Engineering
Year of Conference: 2005