Spreading of oil on water in the surface-tension regime

Chebbi, Rachid

doi:10.1007/s10652-014-9346-3

Cited by 12 publications

(6 citation statements)

References 18 publications

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“…To investigate the film dynamic evolution, the PDMS spreading process on water surface was performed. As shown in Figure 1A, three stages could be observed from the dynamic contact angles of PDMS solution droplets on water surface, which were the gravity‐inertia, gravity‐viscous, and surface tension‐viscous regimes 33 . The third stage was affected by surface tension and solution viscosity of PDMS.…”

Section: Resultsmentioning

confidence: 97%

“…As shown in Figure 1A, three stages could be observed from the dynamic contact angles of PDMS solution droplets on water surface, which were the gravity-inertia, gravity-viscous, and surface tension-viscous regimes. 33 The third stage was affected by surface tension and solution viscosity of PDMS. From Table 1, it could be found that for the PDMS solution, the surface tension σ A was affected by the viscosity, which could be controlled by the pre-crosslinking time (Figure 1B).…”

Section: Effect Of Pre-crosslinking Of Pdms On Film Dynamic Evolutionmentioning

confidence: 99%

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Liquid–liquid interface induced PDMS‐PTFE composite membrane for ethanol perm‐selective pervaporation

Cai

et al. 2022

AIChE Journal

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Pervaporation has great potential in the separation of many significant mixtures.However, excessive penetration of separation layer into the substrate pores enhances the transport resistance of solvent molecules, which impedes the development of pervaporation membrane. In this study, a facile floating-on-water (FOW) method was used to prepare poly(dimethylsiloxane) (PDMS)/polytetrafluoroethylene (PTFE) composite membranes. The formation of separation layer and preparation of composite membrane were step-by-step completed through this liquid-liquid interface induced method. The PDMS layer thickness could be precisely regulated from 0.5 to 8 μm. Moreover, the pore penetration could be controlled by optimizing precrosslinking density, crosslinking time on water and polymer solution volume. The obtained PDMS/PTFE composite membrane exhibited a high flux of 2016 gÁm À2 Áh À1 with the separation factor of 12 when separating ethanol from a 5 wt% ethanol/ water mixture. The performance of the membrane could be stable for over 200 h, exhibiting great potential in ethanol perm-selective pervaporation.

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Section: Resultsmentioning

confidence: 97%

Section: Effect Of Pre-crosslinking Of Pdms On Film Dynamic Evolutionmentioning

confidence: 99%

Liquid–liquid interface induced PDMS‐PTFE composite membrane for ethanol perm‐selective pervaporation

Cai

et al. 2022

AIChE Journal

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“…A few droplet coalescence studies involving the coflow of bulk fluids indicate a longer coalescence time compared to the corresponding stagnant fluids due to a higher lubrication pressure in the film separating the droplet and fluid–fluid interface . The spreading of drops over liquid–liquid/air–liquid interfaces is an outcome of the interplay between gravity, inertia, viscosity, and surface/IFT forces, wherein the spreading length ( l ) scales with time ( t ) as l ∼ t b , and a wide range of exponents ( b ) has been reported in the literature. − Although most of such studies are conducted for air–liquid interfaces, only a few experimental investigations deal with spreading of a droplet at a liquid–liquid interface. , In such studies, spreading was studied in stagnant fluids in macroscale setups, which limits its applicability in a microfluidic co-flowing system as a strong confinement effect, fluid inertia, and negligible gravity would greatly alter the phenomena.…”

Section: Introductionmentioning

confidence: 99%

Migration and Spreading of Droplets across a Fluid–Fluid Interface in Microfluidic Coflow

2022

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Interfacial migration of droplets in microfluidic confinements has significant relevance in cell biology and biochemical assays. So far, studies on passive interfacial migration of droplets are limited to co-flow interfaces having small interfacial tension (IFT ∼ 1 mN/m). Here, we elucidate the migration and spreading of droplets (SiO-1000, SiO-100, FC40, and castor oil as phase 3, P3) across the interface between a pair of coflowing streams (PEG as P1, SiO-100, SiO-20, FC40, and olive oil as P2) having large IFT (∼10 mN/m), with the three different phases immiscible. Interfacial migration involving interfaces of large IFT is facilitated by confining droplets between the channel wall and coflow interface. We find that contact between droplets and the coflow interface is governed by the confinement ratio (i.e., the ratio of drop size to stream width) and the ratio of the capillary numbers of the coflowing streams. Depending on the sign of the spreading parameter (S) of the co-flowing phases, droplet migration or spreading at the interface is observed. While interfacial migration is observed for S 1 < 0 and S 2 > 0, droplet spreading is observed for S 1 < 0 and S 2 < 0, where S 1 and S 2 are P1 and P2 side spreading parameters, respectively. We investigate the droplet migration dynamics and time evolution of the contact line and the interface. Our results show that the speed of interfacial migration increases with increasing spreading parameter contrast between the coflowing phases. In the droplet spreading case, we experimentally study the variation in the spreading length with time, revealing three distinct regimes in good agreement with predictions from analytical scaling. Our study explores the interfacial transport of droplets involving high IFT interfaces, advancing the fundamental understanding of the topic that may find relevance in droplet microfluidics.

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“…Previous works indicated that the initial driving force for the wetting and spreading of an oil droplet on the air–water interface was dominated by the gravity force and balanced by the resistance from the viscous force. , With the progression of the spreading, the oil film became more and more thinner. The surface tension gradient replaced gravity gradually as the main spreading driving force, although the spreading resistance was still dominated by the viscous force. , Investigations on the spreading behavior of oil droplets driven by surface tension gradient have been conducted extensively. − It was demonstrated that the Marangoni convection induced along the air–water interface had a significant impact on the spreading characteristics of the oil droplet and the stability of the thin oil film. − The spreading stability of the oil film on the air–water interface depended closely on its rheological properties (viscosity and elasticity). − However, most of the works on the spreading behavior driven by the Marangoni effect focused on the interfacial flow characteristics of the oil film and the formation mechanism of Marangoni convection along the gas–water interface. , Investigations were scarce into the change in the interface viscosity and elasticity that resulted from the chemical reaction-driven Marangoni convection and its effect on the spreading behavior and the stability of the organic oil film.…”

Section: Introductionmentioning

confidence: 99%

“…The surface tension gradient replaced gravity gradually as the main spreading driving force, although the spreading resistance was still dominated by the viscous force. 14,15 Investigations on the spreading behavior of oil droplets driven by surface tension gradient have been conducted extensively. 16−20 It was demonstrated that the Marangoni convection induced along the air−water interface had a significant impact on the spreading characteristics of the oil droplet and the stability of the thin oil film.…”

Section: Introductionmentioning

confidence: 99%

Chemical Reaction-Driven Spreading of an Organic Extractant on the Gas–Water Interface: Insight into the Controllable Formation of a Gas Bubble-Supported Organic Extractant Liquid Membrane

et al. 2019

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The extraction and recovery of low-concentration valuable metals from various complex aqueous solutions or industrial waste waters have attracted extensive interests in recent years. In our previous works, we suggested a novel technique called bubbling organic liquid membrane extraction by spreading and covering an organic extractant with extremely small volume on the surface of gas bubbles to form a layer of the gas bubble-supported organic liquid membrane for selective extraction and enrichment of low-concentration targets from dilute aqueous solutions. It was found that for successfully performing the bubbling organic liquid membrane extraction, a prerequisite is knowing how to control the formation of a stable organic liquid membrane covered on the surface of gas bubbles. However, once the organic extractant starts to spread on the surface of gas bubbles, the extraction chemical reaction at the interface between the organic extractant liquid membrane and the rare-earth aqueous solution will occur. In the present work, the spreading behavior of the organic extractant P507 on the surface of rare-earth aqueous solutions was investigated and was compared with the behaviors on the surface of deionized water. It was revealed that the spreading of the organic extractant P507 on the surface of aqueous solutions containing rare-earth ions was accelerated because of the occurrence of the chemical reactions at the gas–water interface. The difference in the spreading rate of organic extractant P507 liquid droplets on the surface of deionized water and on that of Er(III) aqueous solutions with an increase in the P507 concentration, the saponification degrees of the P507 extractant, and the preloading amount of Er(III) in the P507 extractant revealed that the chemical reaction at the interface between the spreading P507 thin liquid membrane and the Er(III) aqueous solution would result in the Marangoni convection along the interface, which is in favor of overcoming the resistance from the viscous force when the surface tension gradient replaces gravity as a dominant driving force for the spreading. The present work provides an experimental foundation toward understanding the effect of the interfacial chemical reaction on the spreading behavior of an organic oil droplet on the gas–water interface. It is beneficial for the development of our suggested new technique of bubbling organic liquid membrane extraction and to achieve a controllable generation of a stable gas bubble-supported organic liquid membrane for performing solvent extraction at large aqueous-to-oil phase ratios.

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Spreading of oil on water in the surface-tension regime

Cited by 12 publications

References 18 publications

Liquid–liquid interface induced PDMS‐PTFE composite membrane for ethanol perm‐selective pervaporation

Liquid–liquid interface induced PDMS‐PTFE composite membrane for ethanol perm‐selective pervaporation

Migration and Spreading of Droplets across a Fluid–Fluid Interface in Microfluidic Coflow

Chemical Reaction-Driven Spreading of an Organic Extractant on the Gas–Water Interface: Insight into the Controllable Formation of a Gas Bubble-Supported Organic Extractant Liquid Membrane

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