Article ID Journal Published Year Pages File Type
596069 Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 6 Pages PDF
Abstract

It is interesting to examine from a scientific viewpoint whether surface processes can bring about coalescence of droplets of emulsions (de-emulsions) in the context that de-emulsification is a bulk process rather than a surface one. The de-emulsification by electrode processes and surface catalysis was here applied to water-in-oil emulsions, which are models of water-included petroleum. When DC-voltage was applied to the emulsions composed of salt-included water droplets, current was observed only for the volume fraction of water more than 0.23. This value was regarded as a threshold of the electric percolation. A long-time electrolysis made water droplets coalesce only on the electrode surface, and hence did not lead to de-emulsification in the bulk. We found by a microscope that a hydrophilic glass surface worked as a catalyst of de-emulsification. The de-emulsification was caused by the adsorption of droplets on the glass plate to be flattened. The probability of the de-emulsification was proportional to the volume fraction of the water. It was explained in terms of the model of random collision of droplets on a plane. The adsorption and flattening were applied to removal of water droplets from the emulsions by adding hydrophilic glass powder to the emulsions.

Related Topics
Physical Sciences and Engineering Chemical Engineering Colloid and Surface Chemistry
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