Electroemulsification in a Uniform Electric Field

Abstract

Emulsification using electric fields is an easy alternative to flow-induced drop breakup, and the former is reported to be more effective and economical than the latter, especially when the medium phase is poorly conducting and highly viscous. The emulsification of a coarse water-in-oil emulsion in a uniform electric field is studied. We perform a detailed experimental analysis of the effect of applied electric field strength and the duration of applied electric field on the drop size distribution. The average diameter as well as the time for emulsification decreases with an increase in the intensity of the electric field. Moreover, a narrow size distribution is observed. An average size of a few microns of the dispersed phase could be achieved. New breakup mechanisms at play in the emulsification process are discussed. Identified mechanisms involve charged lobe disintegration, charged drop breakup, chain formation in which several water droplets are interconnected by thin water bridges, electrospraying and charge transfer, and coalescence. The study shows that charged drop disintegration could be the key mechanism of fine emulsification of an initially electrically neutral coarse emulsion.

Dynamics of ferrofluid drop deformations under spatially uniform magnetic fields

“…Destabilization of the interface between a ferrofluid and a non-magnetic fluid was discussed first by Boudouvis et al (1987), and explored further by Engel, Langer & Chetverikov (1999), Abou, Wesfreid & Roux (2000), Lavrova et al (2006), Gollwitzer et al (2007), Chen & Cheng (2008), Mizuta (2011) and Cao & Ding (2014). Multiple works studied the breakup of drops under electric (Sherwood 1988;Basaran et al 1995;Lac & Homsy 2007;Deshmukh & Thaokar 2012;Paknemat, Pishevar & Pournaderi 2012;Karyappa, Naik & Thaokar 2015) or magnetic (Potts, Barrett & Diver 2001;Afkhami et al 2008) fields, as well as the breakup of jets under electric fields (Collins, Harris & Basaran 2007). Drop formation facilitated by electric (Notz & Basaran 1999) and magnetic (Chen, Chen & Lee 2009) fields, and dynamics and instabilities of pendent drops under an electric field (Acero et al 2013;Ferrera et al 2013;Corson et al 2014) were also explored.…”

Non‐coalescence and chain formation of droplets under an alternating current electric field

“…Whether two droplets coalesce completely or partially depends on the competition between electric field and additional pressure caused by the interfacial tension at the tip 26 . When the electric force is stronger than the additional pressure, the Taylor cone is induced at the tip and subsequent tip streaming occurs 27 . The partial coalescence behavior is not always observed as Ca p increases during the experiments.…”

Contactless Method of Emulsion Formation Using Corona Discharge

“… 26 However, caution should be accounted for while using volatile and flammable oils. 25 Due to this flexibility, it has been feasible to produce engineered W/O/W and O/W/O emulsions with selective chemical compositions, droplet sizes, and viscosities for different applications with significantly less energy consumption when compared to the mechanical agitation methods. 27 In addition, the previous works on electroemulsification claim that due to the existence of the built-up charges in the dispersed phase, the overall stability and shelf life of the emulsions are increased.…”