Electrocoalescence in non-uniform electric fields: An experimental study

Mhatre, Sameer; Thaokar, Rochish

doi:10.1016/j.cep.2015.07.025

Cited by 57 publications

(24 citation statements)

References 20 publications

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“…Electric control of droplets in microfluidic channels is a robust approach that can be used to actively control droplet splitting [ 179 , 180 , 181 , 182 , 183 , 184 ], merging [ 179 , 184 , 185 , 186 , 187 , 188 , 189 , 190 , 191 ], and sorting [ 179 , 192 ], which are of great interest in droplet-reaction systems, high-throughput screening, and combinatorial chemistry. In this approach, the electric field is introduced from embedded electrodes to the interface.…”

Section: Electric Control Of Droplet Generationmentioning

confidence: 99%

Microfluidic Production of Multiple Emulsions

2017

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Microfluidic devices are promising tools for the production of monodispersed tuneable complex emulsions. This review highlights the advantages of microfluidics for the fabrication of emulsions and presents an overview of the microfluidic emulsification methods including two-step and single-step methods for the fabrication of high-order multiple emulsions (double, triple, quadruple and quintuple) and emulsions with multiple and/or multi-distinct inner cores. The microfluidic methods for the formation of multiple emulsion drops with ultra-thin middle phase, multi-compartment jets, and Janus and ternary drops composed of two or three distinct surface regions are also presented. Different configurations of microfluidic drop makers are covered, such as co-flow, T-junctions and flow focusing (both planar and three-dimensional (3D)). Furthermore, surface modifications of microfluidic channels and different modes of droplet generation are summarized. Non-confined microfluidic geometries used for buoyancy-driven drop generation and membrane integrated microfluidics are also discussed. The review includes parallelization and drop splitting strategies for scaling up microfluidic emulsification. The productivity of a single drop maker is typically <1 mL/h; thus, more than 1000 drop makers are needed to achieve commercially relevant droplet throughputs of >1 L/h, which requires combining drop makers into two-dimensional (2D) and 3D assemblies fed from a single set of inlet ports through a network of distribution and collection channels.

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Section: Electric Control Of Droplet Generationmentioning

confidence: 99%

Microfluidic Production of Multiple Emulsions

2017

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“…Soon, the application of an electric field became an integral part of water and oil separation from stiff water-in-oil emulsions, reducing the separation time and increasing the efficiency of the process. Since then, researchers have extensively tried to understand the physics of the mechanism of drop coalescence under an electric field both experimentally and numerically (Cottrell & Speed 1911; Allan & Mason 1962; Mhatre, Deshmukh & Thaokar 2015; Mhatre & Thaokar 2015). On application of an electric field each of the water droplets is polarized, which results in a dipolar force of attraction between the droplets.…”

Section: Introductionmentioning

confidence: 99%

Breakup and non-coalescence mechanism of aqueous droplets suspended in castor oil under electric field

2019

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The effect of an electric field on the coalescence of two water droplets suspended in an insulating oil (castor oil) in the non-coalescence regime is investigated. Unlike the immediate breakup of the bridge, as reported in earlier studies, e.g. Ristenpart et al. (Nature, vol. 461 (7262), 2009, pp. 377–380), the non-coalescence observed in our experiments indicate that at strong fields the droplets exhibit a tendency to coalesce, the intervening bridge thickens whereafter the bridge dramatically begins to thin, initiating non-coalescence. Numerical simulations using the boundary integral method are able to explain the physical mechanism of thickening of this bridge followed by thinning and non-coalescence. The underlying reason is the competing meridional and azimuthal curvatures which affect the pressure inside the bridge to become either positive or negative under the effect of electric field induced Maxwell stresses. Velocity and pressure profiles confirm this hypothesis and we are able to predict this behaviour of transitory coalescence followed by non-coalescence.

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“…Their results showed that bigger drops were deformed more than smaller drops under the action of an electric field, and the interfacial tension was significantly lower in the presence of a surfactant. In a similar study by Mhatre and Thaokar [140], the relative merits of symmetric and asymmetric non-uniform and uniform electric fields in the electro-coalescence of three types of crude oil emulsions were investigated. They reported that electro-coalescence was affected by the non-uniformity, as well as asymmetry, of the electric field.…”

Section: Electrical Demulsificationmentioning

confidence: 99%

An Overview of Recent Advances in State-of-the-Art Techniques in the Demulsification of Crude Oil Emulsions

et al. 2019

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The processing of crude oil often requires the extraction of a large amount of water. Frequently, crude oil is mixed with water to form water-in-crude oil emulsions as the result of factors such as high shear at the production wellhead and surface-active substances that are naturally present in crude oil. These emulsions are undesirable and require demulsification to remove the dispersed water and associated inorganic salts in order to meet production and transportation specifications. Additionally, the demulsification of these crude oil emulsions mitigates corrosion and catalyst poisoning and invariably maximizes the overall profitability of crude oil production. Recently, there has been growing research interest in developing workable solutions to the difficulties associated with transporting and refining crude oil emulsions and the restrictions on produced water discharge. Therefore, this paper reviews the recent research efforts on state-of-the-art demulsification techniques. First, an overview of crude oil emulsion types, formation, and stability is presented. Then, the parameters and mechanisms of emulsification formation and different demulsification techniques are extensively examined. It is worth noting that the efficiency of each of these techniques is dependent on the operating parameters and their interplay. Moreover, a more effective demulsification process could be attained by leveraging synergistic effects by combining one or more of these techniques. Finally, this literature review then culminates with propositions for future research. Therefore, the findings of this study can help for a better understanding of the formation and mechanisms of the various demulsification methods of crude oil to work on the development of green demulsifiers by different sources.

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Electrocoalescence in non-uniform electric fields: An experimental study

Cited by 57 publications

References 20 publications

Microfluidic Production of Multiple Emulsions

Microfluidic Production of Multiple Emulsions

Breakup and non-coalescence mechanism of aqueous droplets suspended in castor oil under electric field

An Overview of Recent Advances in State-of-the-Art Techniques in the Demulsification of Crude Oil Emulsions

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