Estimation of the electric field strength required for breaking the water-in-oil emulsion: A thermodynamic approach considering droplets deformation and the effect of interfacial tension

The deformability of droplets in an emulsion, when they approach each other, may affect the stability of emulsion and its phase behavior. In this study we have modified the repulsion potential function between the droplets in order to take this phenomenon into account. Appropriate changes to other parts of the potential function have been made to implement the influence of the geometric alternations due to droplets deformation. We have used the first order Barker–Henderson perturbation theory to derive a thermodynamic model for computing the equilibrium between the emulsified water droplets in oil and the separated aqueous phase. Based on the proposed model, phase diagrams for oil-water emulsions have been determined and the effects of various physical parameters on the equilibrium conditions have been investigated. We have also presented phase diagrams comparing the results considering the drops deformable and non-deformable when they approach each other. The model can favorably lead us to the prediction of the required electric field strength for breaking the stable emulsions. The important physical properties such as the polarity of the droplets, adsorption layer thickness, size of the droplets and interfacial tension are taken into account. The results obtained from the proposed model have been favorably compared with available experimental data. It has been shown that deformation has no effect on the emulsions with relatively large water drops; however, for small droplets the effect of deformation is noticeable and could not be ignored.

Evaluation of the proposed model using the reported experimental data at 298 K [7].Figure optionsDownload as PowerPoint slideHighlights
► Our objective is to estimate the electric field strength for breaking water-in-oil emulsion.
► Phase transition of water droplets exposed to electric field is investigated.
► The first order BH perturbation theory is used in the thermodynamic modeling.
► Physical properties such as droplet size and interfacial tension are considered.
► Deformation has considerable effect on the stability of small droplets.