Effect of electric field intensity on droplet fragmentation in oil-in-water-in-oil (O/W/O) emulsions: A molecular dynamics study

Abstract

Oil-in-water-in-oil (O/W/O) emulsions commonly exist in crude oil treatment, food processing, pharmaceuticals, and cosmetics; however, few related studies have been conducted. To reveal the fragmentation mechanism of droplets in O/W/O emulsions, the behavior of complex droplets under different electric field intensities was investigated using a molecular dynamics method. It was found that the deformation of the intermediate phase (water) and the internal phase (hexane) increased dramatically with the electric field intensity, and the two phases separated when E ≥ 1.1 V∙nm−1, indicating that the complex droplets had been simplified into two simple liquids. Observation of the droplet trajectory shows that the deformation of the internal phase was smaller than that of the intermediate phase, and the internal oil droplet moved toward the high electric potential position. Furthermore, we elaborated the interactions between different phases at the molecular level by means of weak interactions and radial distribution function analysis, and their magnitudes were as follows: Cl− - Na+ > Na+ - Water > Water - Hexane. The electric fragmentation mechanism of the complex droplets was investigated, which provides theoretical guidance for the treatment of O/W/O emulsions by electrodehydration.