Experimental study on the shape–velocity relationship of an ellipsoidal bubble in inorganic salt solutions

Quinn, J.J.; Maldonado, M.; Gómez, C.O.; Finch, J.A.

doi:10.1016/j.mineng.2013.09.003

Cited by 36 publications

(21 citation statements)

References 30 publications

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“…The average relative error σ d /d of the measured equivalent bubble diameters is 10%. Note that this error includes not only the experimental uncertainty but also bubble size variations arising from the bubble shape oscillation [25][26][27]. This is especially true for cases with large initial shape deformation where the bubble size depends on the rotation of the bubbles; bubbles seen from different angles will have different shapes due to waves traveling on the bubble-water interface.…”

Section: Bubble Sizementioning

confidence: 99%

Effects of Salinity on Surface Lifetime of Large Individual Bubbles

Anguelova

Huq

2017

JMSE

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Abstract:The influence of salinity on the characteristics of individual bubbles (2-4 mm in diameter) in fresh and saline water (up to 40 practical salinity units) was investigated. Bubbles were produced by forcing air through capillary tubes. Aqueous solutions in distilled and filtered tap waters with minimized presence of organic additives were used. Salinity, surface tension, and water temperature were monitored. Parameters measured were the bubble surface lifetime, diameter, and rise velocity. The surface lifetime varies widely (in the range of 0.4-35 s) depending on the salinity concentration and the purity of the solutions. Variations with salinity of size and rise velocity of large individual bubbles are discussed. Interpretation of the results in terms of anti-foaming (negative adsorption), as well as the Marangoni and the Gibbs effects, is helpful in understanding the results.

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Section: Bubble Sizementioning

confidence: 99%

Effects of Salinity on Surface Lifetime of Large Individual Bubbles

Anguelova

Huq

2017

JMSE

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“…This might be connected to an overall suppression of the shape oscillation, which is important for the terminal velocity [9]. Indeed, the conclusion was drawn from a recent study, which investigated single bubbles rising in different salt solutions, that NaCl has a distinct influence on the bubble shape [24].…”

Section: Introductionmentioning

confidence: 99%

The Bubble Shape in Contaminated Bubbly Flows: Results for Different NaCl Concentrations in Purified Water

et al. 2018

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Abstract:The bubble shape influences the transfer of momentum and heat/mass between the bubble and the surrounding fluid as well as the flow field around the bubble. The shape is determined by the interaction of the fluid field in the bubble, the physics on the surface, and the surrounding flow field. It is well known that contaminations can disturb the surface physics so that the bubble shape can be influenced. Indeed, an influence of sodium chloride (NaCl) on the hydrodynamics of bubbly flows was shown for air/water systems in previous studies. The aim of the present work is to investigate if, and to what extent, the NaCl concentration affects the bubble shape in bubble columns. For this purpose, several experiments at the Helmholtz-Zentrum Dresden-Rossendorf and at the pilot-scale bubble column at the Politecnico di Milano are evaluated. The experiments were executed independently from each other and were evaluated with different methods. All experiments show that the bubble shape is not distinctly affected in the examined concentration range from 0 to 1 M NaCl, which is in contrast to a previous study on single bubbles. Therefore, the effect of NaCl on the hydrodynamics of bubbly flows is not induced by the bubble shape.

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“…These observations were considered as strong evidence against immobilizing effect of salts despite admitting that there are differences between the rise of a single bubble in a quiescent liquid and the thinning of a liquid film between two colliding bubbles. It is noted that the evidence that the bubble rise velocity in solutions of bubble coalescence inhibiting and non-inhibiting salts is the same as that in pure water is contradictory to the experimental results of Quinn et al (2014a). These contradictory evidences can be attributed to the salts purity since bubbles smaller than 1 mm in diameter show little effect of contamination on bubble size and velocity, while larger bubbles can undergo surface deformation affected by impurities via surface tension and surface viscoelastic properties of the air-water interface (Quinn et al, 2014a).…”

Section: Surface Rheologymentioning

confidence: 85%

“…It is noted that the evidence that the bubble rise velocity in solutions of bubble coalescence inhibiting and non-inhibiting salts is the same as that in pure water is contradictory to the experimental results of Quinn et al (2014a). These contradictory evidences can be attributed to the salts purity since bubbles smaller than 1 mm in diameter show little effect of contamination on bubble size and velocity, while larger bubbles can undergo surface deformation affected by impurities via surface tension and surface viscoelastic properties of the air-water interface (Quinn et al, 2014a). Later the boundary condition of a liquid film between a rising bubble and a TiO2 solid surface during drainage was studied .…”

Section: Surface Rheologymentioning

confidence: 85%

Drainage and stability of foam films during bubble coalescence in aqueous salt solutions

Firouzi¹

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Bubble coalescence and thin liquid films (TLFs) between bubbles known as foam films, are central to many daily activities, both natural and industrial. They govern a number of important processes such as foam fractionation, oil recovery from tar sands and mineral recovery by flotation using air bubbles. TLFs are known to be stabilized by some salts and bubble coalescence in saline water can be inhibited at salt concentrations above a critical (transition) concentration. However, the mechanisms of the inhibiting effect of these salts are as yet contentious. The aim of this work is to characterise the behaviour of saline liquid films both experimentally and theoretically to better understand the mechanisms.The effect of sodium halide and alkali metal salts including NaF, NaBr, NaI, NaCl, KCl and LiCl on the stability of a foam film was investigated by applying the TLF interferometry method. To mimic realistic conditions of bubble coalescence in separation processes, the drainage and stability of TLFs were studied under non-zero bubble (air-liquid interface) approach speeds (10-300 µm/s) utilizing a nano-pump. For each of the salts studied, a critical concentration (Ccr) above which liquid films lasted for up to 50 s depending on the salt type, concentration and the interface approach speed, was determined. For concentrations below Ccr, the saline liquid films either ruptured instantly or lasted for less than 0.2 s. Ccr follows the order NaF

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Experimental study on the shape–velocity relationship of an ellipsoidal bubble in inorganic salt solutions

Cited by 36 publications

References 30 publications

Effects of Salinity on Surface Lifetime of Large Individual Bubbles

Effects of Salinity on Surface Lifetime of Large Individual Bubbles

The Bubble Shape in Contaminated Bubbly Flows: Results for Different NaCl Concentrations in Purified Water

Drainage and stability of foam films during bubble coalescence in aqueous salt solutions

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