The Pristine Oil/Water Interface: Surfactant‐Free Hydroxide‐Charged Emulsions

Beattie, James K.; Djerdjev, Alex M.

doi:10.1002/anie.200453916

Cited by 368 publications

(442 citation statements)

References 18 publications

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“…A similar effect was observed for oil drops in water [19,20]. The experiment showed that ζ-potential of the bubbles (drops) changes with pH from zero at pH = 2-4 up to −120 mV at pH ≈ 10.…”

Section: Introductionsupporting

confidence: 73%

“…The experiment showed that ζ-potential of the bubbles (drops) changes with pH from zero at pH = 2-4 up to −120 mV at pH ≈ 10. The surface density of charges measured for oil drops [20] corresponds roughly n s = (3 − 4) × 10 13 cm −2 at neutral pH. For bubbles in water, the charge density is expected to be in the same range, because the pH dependence of the ζ-potential is similar to that for the drops [21].…”

Section: Introductionmentioning

confidence: 88%

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Surface Assisted Combustion of Hydrogen-Oxygen Mixture in Nanobubbles Produced by Electrolysis

2017

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Abstract:The spontaneous combustion of hydrogen-oxygen mixture observed in nanobubbles at room temperature is a puzzling phenomenon that has no explanation in the standard combustion theory. We suggest that the hydrogen atoms needed to ignite the reaction could be generated on charged sites at the gas-liquid interface. Equations of chemical kinetics augmented by the surface dissociation of hydrogen molecules are solved, keeping the dissociation probability as a parameter. It is predicted that in contrast with the standard combustion, the surface-assisted process can proceed at room temperature, resulting not only in water, but also in a perceptible amount of hydrogen peroxide in the final state. The combustion time for the nanobubbles with a size of about 100 nm is in the range of 1-100 ns, depending on the dissociation probability.

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Section: Introductionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 88%

Surface Assisted Combustion of Hydrogen-Oxygen Mixture in Nanobubbles Produced by Electrolysis

2017

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“…On the contrary, the second model of the e.d.l. for the oilwater and airwater interface stipulates that OH ¹ ions are preferentially adsorbed, 12 which is difficult to understand. The specific adsorption potential of the OH ¹ species requires a very high value to yield a negative surface down to a pH of 34 (i.e., at the i.e.p.)…”

Section: ç Discussionmentioning

confidence: 99%

The Oxide–Water Interface: How Valid Is the Site Dissociation–Surface Equilibria Model?

Healy¹,

Scales²

2012

Chemistry Letters

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The great Dutch school of colloid science of Kruyt, Overbeek, and others developed theoretical and experimental models of the silver halidewater interface. Potentiometric titrations, electrokinetic measurements, and coagulation kinetics set high standards of experimentation. They, further, led to the development of theoretical models, mostly thermodynamic, of the silver halideaqueous electrolyte interface, which allowed quantitative understanding of experimental results. The fundamental step was to recognize that silver and halide ions, as potential-determining ions, controlled the Nernst potential of the interface. At ca. 25°C, as the concentration of silver ions in the bulk solution changed by a factor of 10, the potential of the silver halidewater interface changed by 59 mV. Colloid scientists across the globe in the post-1948 era, additionally wished to understand the properties of colloidal dispersions of simple inorganic oxides such as silica, hematite, and alumina, and more recently, the properties of "latex" particles. In short, it became difficult to apply the theories that allowed understanding of the silver halidewater interface to the understanding of the properties of latex, oxides, and similar colloidal dispersions. Finally, a very recent resurgence in the interest in the electrical double layer (e.d.l.) at the airwater and oilwater interface has fuelled the discussion on the ubiquitous role of protons as potentialdetermining ions (p.d.i.'s) on interfaces ranging from oxides, to lattices, close packed monolayers, and oilwater and air water interfaces. We explore the new thinking on all of these aqueous interfaces. Ç IntroductionFor many years, researchers wishing to understand the interface between inorganic oxides (e.g., SiO 2 , TiO 2 , and Al 2 O 3 ) and aqueous solutions have used a model that describes the ionization of surface hydroxy sites. An undecorated description of this model begins with the surface equilibria:where K + and K ¹ are defined asHere (aH + ) s is the activity of protons at the surface, and N + , N 0 , and N ¹ are the number of positive, neutral, and negative sites, respectively, where the total number of sites in the undecorated model isAt the pH of the isoelectric point/point of zero charge (i.e.p./ p.z.c), (pH 0 ), N ¹ = N + , such thatandThe total surface charge iswhere e is the electronic charge. The activity of protons at the surface is given by the Boltzmann equation aswhere ¼ 0 is the total double layer potential, k is the Boltzmann constant, and T is the temperature. The simple electrical double layer model iswhere more complete models would be represented aswhere · β , is the Stern layer charge, which is populated, in simple electrolyte systems, with bound anions and cations such as Na + and Cl ¹ . For the present discussion, the model we use, i.e., more or less decorated, is not important.If ¼ N is the potential given by the Nernst equation, thenThis non-Nernstian term is a function of ¦pK « , supporting electrolyte concentration, and the total number of su...

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“…For pristine emulsions can spontaneously enrich hydroxide ions at the oil/water interfaces. 29 The surfaces of the oil droplets, stabilized by hydroxide ions are therefore negatively charged and their pH are much higher than that in bulk water. By this theory, Wang and coworkers utilized the oil/water emulsions as the sacri¯cial template to prepare PDA capsules in NaOH (pH 8.2) solution, Hydroxide ions do not only stabilize the oil/water interface, but also replace TRIS bu®er to provide an alkaline circumstance for oxidation of DA.…”

Section: Soft Templatementioning

confidence: 99%

Polydopamine used as Hollow Capsule and Core–Shell Structures for Multiple Applications

Cui

Yin

et al. 2015

NANO

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Polydopamine (PDA) capsule and core-shell structures with tailored structures and properties are of particular interests due to their multifunctions and potential applications as new colloidal structures in diverse¯elds. Among the available fabrication methods, PDA¯lm onto colloidal particles followed by selective template removal has attracted extensive attention due to its advantages of precise control over the size, wall thickness and functions of the obtained capsules. The past several years has witnessed a rapid increase of research concerning the new fabrication strategies, functionalization and applications of this kind of capsules and core-shell structures, particularly in many¯elds such as drug delivery, catalysis, antibacterial, etc. In this review, the very recent progress of the capsule and core-shell structures based on PDA are summarized. There are basically two sections, including the fabrication process of PDA capsules, core-shell structures, and the various applications based on PDA.

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The Pristine Oil/Water Interface: Surfactant‐Free Hydroxide‐Charged Emulsions

Cited by 368 publications

References 18 publications

Surface Assisted Combustion of Hydrogen-Oxygen Mixture in Nanobubbles Produced by Electrolysis

Surface Assisted Combustion of Hydrogen-Oxygen Mixture in Nanobubbles Produced by Electrolysis

The Oxide–Water Interface: How Valid Is the Site Dissociation–Surface Equilibria Model?

Polydopamine used as Hollow Capsule and Core–Shell Structures for Multiple Applications

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