Influence of surface properties and bulk viscosity on bubble size prediction during foaming operation

Préval, Eugénie Séguineau de; Ducept, Fabrice; Mary, Gilles; Cuvelier, Gérard; Mezdour, Samir

doi:10.1016/j.colsurfa.2013.05.025

Cited by 22 publications

(11 citation statements)

References 38 publications

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“…In fact, the correlation that we have drawn above agrees with results from other studies using pair bubbles (Orvalho et al, 2015) or measuring bubble size distribution (De Preval et al, 2014).…”

Section: Effect Of the Solution Viscosity On The Drainage And Stabilisupporting

confidence: 82%

Stability and coalescence of bubbles in salt solutions in a bubble column and thin liquid films

Nguyen¹

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Salts are known to inhibit bubble coalescence at the concentration greater than a critical (transition) concentration. The phenomenon of bubble coalescence governs the size distribution of bubbles, which is vital to many natural and industrial processes including mass transfer in the ocean, multiphase reactors and mineral recovery in froth flotation. Despite intensive studies over nearly a century resulting in multiple hypotheses, mechanisms of the coalescence inhibition are still unclear.Researchers have greatly agreed that it is the liquid films between bubbles that control the coalescence and must be firstly understood. Surprisingly, most studies have just focused on the bubble tests, but there was a lack of comprehensive studies about the liquid films in a surfactant-free salt system. This thesis aims to provide experimental evidence and extend the current understanding of the liquid film stability and coalescence in salt solutions.Firstly, the effect of superficial gas velocity (3.5, 10, and 18 mm/s), salt type (NaCl, NaI and CsCl) and concentration (0.001M to 3M) on bubble coalescence and gas holdup in a small bubble column were studied. For the first time, it was found that the transition concentration for coalescence inhibition is not a unique entity of salts as reported but it decreases with increasing gas velocity, which highlights the importance of hydrodynamic conditions. The results also confirmed the ion specific responses of investigated salts to transition concentration and gas holdup.To understand the coalescence, liquid films of the simplest subject, deionised water (DI), were studies using the micro-interferometry method with the Sheludko cell. It was showed that films of DI water drained very fast and ruptured instantly when two bubbles were first brought into contact.However, the film drainage rate and rupture thickness sharply decreased and the film lifetime steeply increased with increasing contact time up to 10 min, but then they levelled off. It was argued that the phenomenon was due to the migration of inherently dissolved gases which act as the long-range hydrophobic attraction. The JC Erickson et al.' theory of the hydrophobic attraction and the extended Stefan-Reynolds models to include the air/water surface mobility were also employed. The liquid film study was then extended for salts without a presence of surfactants. Drainage and stability of liquid films in different salts (LiCl, NaCl, KCl, CsCl, KNO3, NaClO3, CaCl2, and MgSO4) over a wider range of concentration (0.001M -3M) were studied in the close (saturation) Sheludko cell with the strictly controlled saturation level and surface contact time. Films of all salts drained slower and lasted longer with increasing salt concentration. Also, the so-called non-inhibiting ii salt, NaClO3, indeed inhibits coalescence at high concentrations (greater than 1M). The effect of the DLVO forces was totally ruled out. Based on the correlation between the experimental results and the data of oxygen solubility and solution viscosity, i...

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Section: Effect Of the Solution Viscosity On The Drainage And Stabilisupporting

confidence: 82%

Stability and coalescence of bubbles in salt solutions in a bubble column and thin liquid films

Nguyen¹

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“…The higher the rotor speed, the smaller the bubbles. This phenomenon has previously been described by numerous authors [4,[24][25][26][27]. High rotor speeds generate larger shear strains, which favor the splitting of bubbles, which were consequently smaller at higher rotor speeds.…”

Section: From Surface Properties To Foam Structurementioning

confidence: 67%

Impact of Interfacial Characteristics on Foam Structure: Study on Model Fluids and at Pilot Scale

Mezdour

Préval

Granda

et al. 2017

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-Foams represent an important area of research because of their relevance to many industrial processes. In continuous foaming operations, foaming ability depends on the process parameters and the characteristics of the raw materials used for foamed products. The effects of fluid viscosity and equilibrium surface tension on foam structure have been studied extensively. Furthermore, as surface active agents diffuse to the interface, they can modify other interface properties through their adsorption, such as interfacial rheology and surface tension kinetics. In order to better understand how these two interfacial properties influence foam structuring, we formulated model foaming solutions with different interface viscoelasticity levels and adsorption rates, but all with the same equilibrium surface tension and viscosity. The solutions were made up of a surface active agent and glucose syrup, so as to maintain a Newtonian behaviour. Five surface active agents were used: Whey Protein Isolate (WPI), sodium caseinate, saponin, cetyl phosphate and Sodium Dodecyl Sulphate (SDS), at concentrations ranging from 0.1% to 1%. Their molecular characteristics, and their interaction with the glucose syrup, made it possible to obtain a range of interface viscoelasticities and surface tension kinetics for these model solutions. The solutions were whipped in a continuously-operating industrial foaming device in order to control process parameters such as shearing and overrun, and to ensure that the experiment was representative of industrial production. The structure of the foams thus obtained foams was then determined by characterising bubble size using image analysis. For all the model solutions, both the viscoelastic moduli and apparent diffusion coefficient were linked to foam structure. The results showed that both high interface viscoelasticity and rapid diffusion kinetics induced a foam structure containing small bubbles. Both effects, as well as the impact of the shearing rate, through the rotor speed, were then integrated in a predictive model for bubble size.Résumé -Effets des propriétés interfaciales sur la structuration de mousses : étude sur produits modèles et à l'échelle pilote -Les mousses représentent un domaine de recherche important en raison de leur pertinence dans de nombreux procédés industriels. Dans l'opération de foisonnement en continu, la capacité moussante dépend des paramètres du procédé et les caractéristiques des matières premières utilisées. L'effet de la viscosité du fluide et de la tension superficielle à l'équilibre sur la structure de la mousse a été largement étudié. Cependant, lorsque les agents tensio-actifs diffusent aux interfaces, ils s'y adsorbent et modifient ainsi les autres propriétés de l'interface, en particulier la rhéologie interfaciale et la cinétique de tension superficielle. Afin de mieux comprendre comment ces propriétés interfaciales influent sur la structuration de la mousse, nous avons formulé des solutions

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“…For very high composite foams (GF‐70 and GF‐80) this phenomenon becomes significant due to the very low workability of the composite synthesis slurry. This promotes the bubble break‐up caused by the increased viscous force acting on the growing bubbles and also hinders the coalescence phenomena due to drainage of the film at the interface that requires more time . Furthermore, during the foaming evolution, the glass‐siloxane slurry progressively becomes denser due to the occurring crosslinking reaction that favors gas cells shrinkage .…”

Section: Resultsmentioning

confidence: 99%

“…This promotes the bubble break-up caused by the increased viscous force acting on the growing bubbles and also hinders the coalescence phenomena due to drainage of the film at the interface that requires more time. 45 Furthermore, during the foaming evolution, the glass-siloxane slurry progressively becomes denser due to the occurring crosslinking reaction that favors gas cells shrinkage. 46 Moreover, the presence of glass powder in the siloxane-based slurry could influence the foaming kinetics due to chemical interaction between constituents.…”

Section: Foam Morphologymentioning

confidence: 99%

Micro‐tomographic characterization of composite recycled glass‐silicone foams for applications in civil engineering

Calabrese

Scalici

Khaskhoussi

et al. 2019

J of Applied Polymer Sci

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Noninvasive X‐ray micro‐computed tomography was applied for a complete quantitative and qualitative analysis of the cellular structure of composite foams constituted by a silicone matrix and a glass production waste filler. Composite foams with different glass filler weight content in the range 0–80% were synthesized and characterized. The tomographic analysis was employed in order to assess the structural heterogeneities, void fraction values, and bubble size distribution for all composite foams. The 3D micro‐CT images analysis, performed at different cross‐sections, highlighted heterogeneous cell growth or more elongated cells in the case of low and high filler content foams, respectively. Batch with 60% of glass filler was identified as a composite foam with effective void fraction values and relatively uniform spheroidal cellular structure (average sphericity 0.723 and diameter 0.107 mm). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48718.

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Influence of surface properties and bulk viscosity on bubble size prediction during foaming operation

Cited by 22 publications

References 38 publications

Stability and coalescence of bubbles in salt solutions in a bubble column and thin liquid films

Stability and coalescence of bubbles in salt solutions in a bubble column and thin liquid films

Impact of Interfacial Characteristics on Foam Structure: Study on Model Fluids and at Pilot Scale

Micro‐tomographic characterization of composite recycled glass‐silicone foams for applications in civil engineering

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