Demulsification of W/O Emulsion under Applied AC Potential
1983 Volume 9 Issue 3 Pages 263-269
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1983 Volume 9 Issue 3 Pages 263-269
The bottleneck of W/O/W emulsion extraction seems to lie in its final stage, i. e. the breaking of W/O emulsion (demulsification). This work was undertaken to ascertain the feasibility of the AC electrical method for the demulsification and to clarify the fundamental characteristics of the method.
The W/O emulsions used were made from an aqueous solution of NaCl and kerosene, dissolving 4 vol% of Span 80 with a rotary disperser. The average diameters of the dispersed water droplets, dp, were in the range of 3.2-4.7μm. The emulsions were found to be stable in both a centrifugal demulsification test and a thermal one. The applications of AC potential of 1-12kV, between a nonconductive electrode of glass in the emulsion layer and the underlying water layer, caused a marked decrease in emulsion stability, and a clear water layer was formed. The throughput rates V of the clear water were expressed as
where H is the distance between electrodes, E the applied AC potential, μ the viscosity of the emulsion, μc the viscosity of the oil phase and ET the transition potential, which is in the range of 6-8kV.
In conclusion, the W/O emulsion can be broken by the AC electrical method, provided that the diameter of the water droplets is larger than 1μm.
