Controlling the surface charge of water droplets in non-polar oils

Schoeler, Andreas M.; Josephides, Dimitris N.; Sajjadi, Shahriar; Mesquida, Patrick

doi:10.1016/j.colsurfa.2014.07.035

Cited by 14 publications

(16 citation statements)

References 26 publications

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“…This mechanism of droplet addressing, however without free surface, was reported e.g. by Schoeler et al [16] .The effect of direct interaction of ionic surfactans at the oil-water interface with electric field was not studied in our work. Oil droplets created on the surface of a surfactant solution did not show enough stability and often spontaneously moved to the chamber walls before any electrical field could be applied.…”

Section: Discussionmentioning

confidence: 54%

“…Hydrophilic ionic groups of surfactants then probably form surface electric charge on kerosene droplets. Schoeler et al [16] showed that, for classical waterin-oil systems, the concentration of the surface charge at the interface can be tuned by a change in the surfactant concentration that is below the critical micelle limit. This finding was proved by the migration of water droplets to the oppositely charged electrode.…”

Section: Introductionmentioning

confidence: 99%

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Electric Field Driven Addressing of Oil-in-Water Droplets in the Presence of Gradients of Ionic and Nonionic Surfactants

Tuček

Beránek

Vobecká

et al. 2016

IEEE Trans. on Ind. Applicat.

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We deal with controlled transport (addressing) of dielectric kerosene droplets dispersed on water surface by DC electric field in the presence of surfactants. Experimental planar microfluidic platform with a central chamber and two electrode compartments enables formation of concentration gradients of cationic, anionic or nonionic surfactants. We show that a kerosene droplet always moves away from the surfactant reservoir due to the Marangoni phenomenon. The release of ionic surfactants can be well controlled by imposed electric field. Once surfactant molecules reach the surface of the water phase, the Marangoni phenomenon pulls the kerosene droplet in the direction from the surfactant reservoir. Thus the observed mechanism does not rely on the classical electrophoretic migration of charged macroscopic objects -droplets. As the dependence of droplet motion on the absolute value of electric field strength is linear, apparent droplet mobilities are evaluated. Finally we discuss the use of the observed phenomenon for droplet addressing in fluidic systems.

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Section: Discussionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Electric Field Driven Addressing of Oil-in-Water Droplets in the Presence of Gradients of Ionic and Nonionic Surfactants

Tuček

Beránek

Vobecká

et al. 2016

IEEE Trans. on Ind. Applicat.

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“…As discussed earlier the rate of reaction for the hydroformylation is besides the 1‐octene concentration especially depended on the local catalyst concentration. Lately it was shown by Schoeler et al and Gray‐Weale et al that in two phase systems with water and non‐polar solvents negative ions concentrate at the surface due to dipole moment fluctuations . Assuming that the rhodium is coordinated by a three times negatively charges TPPTS ligands this could mean that the catalyst complex has an enlarged chance to be located at the interface.…”

Section: Resultsmentioning

confidence: 99%

Considerations on film reactivity in the aqueous biphasic hydroformylation

2017

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In experiments and kinetic models it was shown that the reaction rate of the biphasic aqueous hydroformylation of 1octene is linear dependent on the created interfacial area. This phenomenon is directly linked to the question whether the reaction takes place in the bulk phase and is mass transfer limitation or at the surface which would mean an increase of reaction space. To evaluate the place of reaction a mass transfer analysis has been carried out. No mass transfer limitation for the gaseous components carbon monoxide and hydrogen as well as the olefin 1-octene was determined for the aqueous catalyst phase by calculating the Hatta numbers. With this observation it is possible to exclude the mass transfer as a potential influence and hence the aqueous bulk as the place of reaction. Thus the reaction is most probably surface active. This can be either explained the increase in film volume fraction where non-polar substrate as well as polar catalyst complex is present or through an increased catalyst concentration at the surface through dipole moment fluctuations.Experimental Materials 1-Hexene (971%), 1-octene (991%), and 1-decene (95%) were purchased from Acros Organics; 1-dodecene was V tot 5 0.001 m 3 , u 5 0.6, c Rh 5 0.5 mol m 23 aq , P/Rh 5 10, precursor 5 [Rh(cod)Cl]2, T 5 353.15 K, pH 5 5.5, p tot 5 8 MPa, p H2 /p CO 5 1, t 5 1.5 h. 5 163 V tot 5 0.001 m 3 , u 5 0.6, c Rh 5 0.5 mol m 23 aq, P/Rh 5 10, precursor 5 [Rh(cod)Cl]2, T 5 353.15 K, pH 5 5.5, p tot 5 8 MPa, p H2 /p CO 5 1, t 5 1.5 h. 5 V tot 5 0.001 m 3 , u 5 0.6, c Rh 5 0.5 mol m 23 aq, P/Rh 5 10, precursor 5 [Rh(cod)Cl]2, T 5 353.15 K, pH 5 5.5, p tot 5 8 MPa, p H2 /p CO 5 1, t 5 1.5 h. 1HX 5 1-hexene, 1OC 5 1-octene, 1DC 5 1-decene.V tot 5 0.001 m 3 , u 5 0.6, c Rh 5 0.5 mol m 23 aq, P/Rh 5 10, precursor 5 [Rh(cod)Cl]2, T 5 353.15 K, pH 5 5.5, p tot 5 8 MPa, p H2 /p CO 5 1, t 5 1.5 h.

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“…In physical chemistry, the ECD system can be utilized for understanding intermolecular forces by theoretically [92] and experimentally [57,58] investigating interactions between two immiscible fluids system (ionic liquid/silicone oil) or by molecular dynamics simulations [66]. In surface science, controlling the surface charge on a droplet by chemical or physical methods is an interesting topic [93,94]. Besides, the droplet charging by liquid-solid contact electrification has been actively reported as a novel energy harvesting method [44][45][46][47][48]95].…”

Section: Fundamentals and Applicationsmentioning

confidence: 99%

Next generation digital microfluidic technology: Electrophoresis of charged droplets

2015

Korean J. Chem. Eng.

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Contact charging of a conducting droplet in a dielectric medium is introduced as a novel and useful digital microfluidic technology as well as an interesting scientific phenomenon. The history of this phenomenon, starting from original observations to its interpretations and applications, is presented. The basic principle of the droplet contact charging is also presented. Several fundamental aspects of the droplet contact charging from view points of electrochemistry, surface science, electrocoalescence, and electrohydrodynamics are mentioned. Some promising results for future applications and potential features as a next generation digital microfluidic technology are discussed, especially for 3D organ printing. Finally, implications and significance of the proposed technology for chemical engineering community are discussed.

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Controlling the surface charge of water droplets in non-polar oils

Cited by 14 publications

References 26 publications

Electric Field Driven Addressing of Oil-in-Water Droplets in the Presence of Gradients of Ionic and Nonionic Surfactants

Electric Field Driven Addressing of Oil-in-Water Droplets in the Presence of Gradients of Ionic and Nonionic Surfactants

Considerations on film reactivity in the aqueous biphasic hydroformylation

Next generation digital microfluidic technology: Electrophoresis of charged droplets

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