Effect of DC electric field on coalescence and breakup behaviors of binary emulsion nanodroplets

Abstract

In this paper, molecular dynamics simulations are carried out to investigate the effect of a DC electric field on the coalescence and breakup behaviors of binary emulsion nanodroplets. The results indicate that the raised strength of the electric field promotes the efficiency of the electrocoalescence, and simultaneously a polarizing layer is formed by the strong hydrogen bonds. The polarizing layer inhibits the internal component to separate from the droplet through reducing the interfacial tension between the water and n-octane components. Moreover, the increases in volume content of the internal component promote the electrocoalescence first and then inhibit it in the same electric field, which depends on the competition between the electrostatic attraction and the inertia of the droplets themselves. Meanwhile, the increases in the volume content break the effect of the hydrogen bond and induce the local liquid gap thinning. Therefore, the breakup of the binary emulsion droplets with a larger volume content happens more easily at the thinner edges. In addition, the critical electric field strength corresponding to the breakup of the droplets increases first and then decreases with the volume fraction increasing, which is better for recovering the oil component but worse for the efficiency of electrocoalescence.