The role of surfactant type and bubble surface mobility in foam rheology

Abstract Molten salt reactors (MSRs) are a family of advanced, generation-IV, nuclear reactors that use a circulating molten alkali fluoride fuel salt as both a primary working fluid and a fuel matrix. Since the fuel salt is liquid, gases become entrained in the fuel salt flow, and these entrained gases are called circulating voids. This paper reviews some aspects of circulating voids on reactor behavior. A formal definition of the circulating void fraction is given. A time-line of Oak Ridge reports on circulating void behavior is presented. Methods to measure the circulating void fraction are described. Foam induced by gas entrained in the fuel salt is discussed. The discovery of circulating voids in the molten salt reactor experiment (MSRE) is detailed. Aspects related to bubble size and interfacial area are reviewed. The Laplace pressure is examined. The void and pressure coefficients of reactivity are examined. Some requirements for a bubble model for xenon behavior analysis are proposed. The effects of bubble surface mobility are examined. Finally, sources of gas production in the fuel salt are investigated.

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Oxygen surface mobility and isotopic exchange on oxides: role of the nature and the structure of metal particles

Applied Catalysis A General ◽

10.1016/s0926-860x(00)00537-8 ◽

2000 ◽

Vol 202 (2) ◽

pp. 231-241 ◽

Cited By ~ 62

Author(s):

C. Descorme ◽

D. Duprez

Keyword(s):

Isotopic Exchange ◽

Metal Particles ◽

Surface Mobility ◽

Structure Of Metal ◽

Oxygen Surface

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Bubble Rise Velocity and Surface Mobility in Aqueous Solutions of Sodium Dodecyl Sulphate and n-Propanol

Minerals ◽

10.3390/min9120743 ◽

2019 ◽

Vol 9 (12) ◽

pp. 743

Author(s):

Pavlína Basařová ◽

Yuliya Kryvel ◽

Jakub Crha

Keyword(s):

Surface Tension ◽

Aqueous Solutions ◽

Sodium Dodecyl Sulphate ◽

Sodium Dodecyl ◽

Bubble Surface ◽

Rise Velocity ◽

Bubble Rise ◽

Spherical Bubble ◽

Surface Mobility ◽

Bubble Rise Velocity

Aqueous solutions of simple alcohols exhibit many anomalies, one of which is a change in the mobility of the bubble surface. This work aimed to determine the effect of the presence of another surface-active agent on bubble rise velocity and bubble surface mobility. The motion of the spherical bubble in an aqueous solution of n-propanol and sodium dodecyl sulphate (SDS) was monitored by a high-speed camera. At low alcohol concentrations (xP < 0.01), both the propanol and SDS molecules behaved as surfactants, the surface tension decreased and the bubble surface was immobile. The effect of the SDS diminished with increasing alcohol concentrations. In solutions with a high propanol content (xP > 0.1), the SDS molecules did not adsorb to the phase interface and thus, the surface tension of the solution was not reduced with the addition of SDS. Due to the rapid desorption of propanol molecules from the bottom of the bubble, a surface tension gradient was not formed. The drag coefficient can be calculated using formulas for the mobile surface of a spherical bubble.

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Effects of the surface mobility on the oxidation of adsorbed CO on platinum electrodes in alkaline media. The role of the adlayer and surface defects

Physical Chemistry Chemical Physics ◽

10.1039/c1cp21909j ◽

2011 ◽

Vol 13 (37) ◽

pp. 16762 ◽

Cited By ~ 28

Author(s):

Enrique Herrero ◽

Qing-Song Chen ◽

Javier Hernández ◽

Shi-Gang Sun ◽

Juan M. Feliu

Keyword(s):

Surface Defects ◽

Alkaline Media ◽

Platinum Electrodes ◽

Surface Mobility ◽

Adsorbed Co

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Foaming and rheological properties of aqueous solutions: an interfacial study

Reviews in Chemical Engineering ◽

10.1515/revce-2020-0060 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Badri Vishal

Keyword(s):

Rheological Properties ◽

Industrial Applications ◽

Bubble Surface ◽

Point Of View ◽

Interfacial Rheology ◽

Foaming Agents ◽

Aqueous Foam ◽

Air Water Interface ◽

Foam Rheology ◽

Low Shear

Abstract Although aqueous foam is composed of simple fluids, air and water, it shows a complex rheological behavior. It exhibits solid-like behavior at low shear and fluid-like behavior at high shear rate. Therefore, understanding such behavior is important for many industrial applications in foods, pharmaceuticals, and cosmetics. Additionally, air–water interface of bubble surface plays an important role in the stabilizing mechanism of foams. Therefore, the rheological properties associated with the aqueous foam highly depend on its interfacial properties. In this review, a systematic study of aqueous foam are presented primarily from rheology point of view. Firstly, foaming agents, surfactants and particles are described; then foam structure was explained, followed by change in structure under applied shear. Finally, foam rheology was linked to interfacial rheology for the interface containing particles whose surface properties were altered by surfactants.

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Thermodynamic Model of the Role of Hydrogen Dilution in Plasma Deposition of Microcrystalline Silicon

MRS Proceedings ◽

10.1557/proc-664-a1.5 ◽

2001 ◽

Vol 664 ◽

Author(s):

J Robertson

Keyword(s):

Vapour Deposition ◽

Plasma Deposition ◽

Chemical Vapour ◽

Microcrystalline Silicon ◽

Surface Mobility ◽

Hydrogen Dilution ◽

Surface Nucleation ◽

Precursor Phase ◽

Hydrogenated Amorphous

ABSTRACTHydrogen dilution is used to promote the nucleation and growth of microcrystalline Si (μc-Si) by plasma enhanced chemical vapour deposition (PECVD). The free energy of μc-Si and hydrogenated amorphous silicon (a-Si:H) is analysed as a function of Si:H composition in order to derive the effect of hydrogen dilution. It is shown that increasing the hydrogen content of the a-SiHx precursor phase increases the relative stability of μc-Si slightly, but strongly increases the driving force for nucleation. The higher stability of μc-Si is the fundamental origin of the higher etch rates of a-Si:H, while surface mobility models do not account for sub-surface nucleation of μc-Si.

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Mobile-surface bubbles and droplets coalesce faster but bounce stronger

Science Advances ◽

10.1126/sciadv.aaw4292 ◽

2019 ◽

Vol 5 (10) ◽

pp. eaaw4292 ◽

Cited By ~ 6

Author(s):

Ivan U. Vakarelski ◽

Fan Yang ◽

Yuan Si Tian ◽

Er Qiang Li ◽

Derek Y. C. Chan ◽

...

Keyword(s):

Liquid Interfaces ◽

Oil Processing ◽

Surface Mobility ◽

Wide Range ◽

Multiphase Systems ◽

Liquid Emulsion ◽

Emulsion Systems ◽

The Stability ◽

Interfacial Mobility

Enhancing the hydrodynamic interfacial mobility of bubbles and droplets in multiphase systems is expected to reduce the characteristic coalescence times and thereby affect the stability of gas or liquid emulsions that are of wide industrial and biological importance. However, by comparing the controlled collision of bubbles or water droplets with mobile or immobile liquid interfaces, in a pure fluorocarbon liquid, we demonstrate that collisions involving mobile surfaces result in a significantly stronger series of rebounds before the rapid coalescence event. The stronger rebound is explained by the lower viscous dissipation during collisions involving mobile surfaces. We present direct numerical simulations to confirm that the observed rebound is enhanced with increased surface mobility. These observations require a reassessment of the role of surface mobility for controlling the dynamic stability of gas or liquid emulsion systems relevant to a wide range of processes, from microfluidics and pharmaceuticals to food and crude oil processing.

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