Mechanisms and conditions that affect phase inversion processes: A review

Maffi, Juan Martín; Meira, G. R.; Estenoz, Diana Alejandra

doi:10.1002/cjce.23853

Cited by 27 publications

(22 citation statements)

References 251 publications

(492 reference statements)

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“…Emulsions, such as mixtures of oil and water, have numerous industrial applications, including enhanced oil recovery, liquid-liquid extraction, drug delivery systems, and food processing (Mcclements 2007;Mandal et al 2010;Maffi, Meira & Estenoz 2021). We can distinguish two types of emulsions: oil droplets in water and water droplets in oil, which we abbreviate with O/W and W/O, respectively (Salager et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Physical mechanisms for droplet size and effective viscosity asymmetries in turbulent emulsions

Wang

Vuren

et al. 2022

J. Fluid Mech.

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By varying the oil volume fraction, the microscopic droplet size and the macroscopic rheology of emulsions are investigated in a Taylor–Couette turbulent shear flow. Although here oil and water in the emulsions have almost the same physical properties (density and viscosity), unexpectedly, we find that oil-in-water (O/W) and water-in-oil (W/O) emulsions have very distinct hydrodynamic behaviours, i.e. the system is clearly asymmetric. By looking at the micro-scales, the average droplet diameter hardly changes with the oil volume fraction for O/W or for W/O. However, for W/O it is about $50\,\%$ larger than that of O/W. At the macro-scales, the effective viscosity of O/W is higher when compared to that of W/O. These asymmetric behaviours are expected to be caused by the presence of surface-active contaminants from the walls of the system. By introducing an oil-soluble surfactant at high concentration, remarkably, we recover the symmetry (droplet size and effective viscosity) between O/W and W/O emulsions. Based on this, we suggest a possible mechanism responsible for the initial asymmetry and reach conclusions on emulsions where interfaces are fully covered by the surfactant. Next, we discuss what sets the droplet size in turbulent emulsions. We uncover a $-6/5$ scaling dependence of the droplet size on the Reynolds number of the flow. Combining the scaling dependence and the droplet Weber number, we conclude that the droplet fragmentation, which determines the droplet size, occurs within the boundary layer and is controlled by the dynamic pressure caused by the gradient of the mean flow, as proposed by Levich (Physicochemical Hydrodynamics, Prentice-Hall, 1962), instead of the dynamic pressure due to turbulent fluctuations, as proposed by Kolmogorov (Dokl. Akad. Nauk. SSSR, vol. 66, 1949, pp. 825–828). The present findings provide an understanding of both the microscopic droplet formation and the macroscopic rheological behaviours in dynamic emulsification, and connects them.

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Section: Introductionmentioning

confidence: 99%

Physical mechanisms for droplet size and effective viscosity asymmetries in turbulent emulsions

Wang

Vuren

et al. 2022

J. Fluid Mech.

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“…The development of comprehensive mathematical models to predict such inversion points remains still an interesting chemical engineering challenge. [7] Toward autothermal and hydrogen-producing sorbent regeneration for calcium-looping Arian Ebneyamini, John Grace, Naoko Ellis, Choon Jim Lim…”

Section: Gael Plantard Chloé Dezani Enrique Ribeiro Brice Reoyo-prmentioning

confidence: 99%

“…The development of comprehensive mathematical models to predict such inversion points remains still an interesting chemical engineering challenge. [ 7 ]…”

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confidence: 99%

Issue Highlights

2020

Can J Chem Eng

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When polymer researchers are intentional about designing materials informed by a good understanding of polymerization kinetics and/or polymer modification procedures, structure-property relationships, and application requirements, they can be confident that their process makes the best possible use of resources and that their product is optimal for the targeted application. This article describes how the evolution of polymer research has led to the design of polymeric materials, provides a general framework that has been developed to guide the design process, and demonstrates the effectiveness and versatility of the design framework through two in-depth case studies (polymeric sensing materials and water-soluble polymers). [1]

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“…This could turn unsafe and undesired, especially for skin and cosmetic applications . In addition, hydrophilic–lipophilic balance (HLB), critical micelle concentration (CMC), viscosity, and density of the continuous and dispersed phases limit the types of the emulsions that can be made using low-energy methods …”

Section: Introductionmentioning

confidence: 99%

“…22 In addition, hydrophilic−lipophilic balance (HLB), critical micelle concentration (CMC), viscosity, and density of the continuous and dispersed phases limit the types of the emulsions that can be made using low-energy methods. 23 Although all of the discussed methods have shown promise for industrial applications, they introduce common limitations. Alteration of chemical properties, due to a high concentration of surfactants or high processing temperature, and change of physical properties, due to high mechanical pressure in combination, along with the inability for continuous production of emulsions are among the most common difficulties that the commercially available emulsification methods represent.…”

Section: Introductionmentioning

confidence: 99%

Contactless Method of Emulsion Formation Using Corona Discharge

et al. 2022

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Electroemulsification methods use electrohydrodynamic (EHD) forces to manipulate fluids and droplets for emulsion formation. Here, a top-down method is presented using a contactless corona discharge for simultaneous emulsion formation and its pumping/collection. The corona discharge forms using a sharp conductive electrode connected to a high-voltage source that ionizes water vapor droplets (formed by a humidifier) and creates an ionic wind (electroconvection), dragging them into an oil medium. The nonuniform electric field induced by the corona discharge also drives the motion of the oil medium via an EHD pumping effect utilizing a modulated bottom electrode geometry. By these two effects, this contactless method enables the immersion of the water droplets into the moving oil medium, continuously forming a water-in-oil (W/O) emulsion. The impact of corona discharge voltage, vertical and horizontal distances between the two electrodes, and depth of the silicone oil on sizes of the formed emulsions is studied. This is a low-cost and contactless process enabling the continuous formation of the W/O emulsions.

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Mechanisms and conditions that affect phase inversion processes: A review

Cited by 27 publications

References 251 publications

Physical mechanisms for droplet size and effective viscosity asymmetries in turbulent emulsions

Physical mechanisms for droplet size and effective viscosity asymmetries in turbulent emulsions

Issue Highlights

Contactless Method of Emulsion Formation Using Corona Discharge

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