Single micro-bubble generation by pressure pulse technique

Najafi, Aref Seyyed; Xu, Zhenghe; Masliyah, Jacob H.

doi:10.1016/j.ces.2007.12.013

Cited by 20 publications

(9 citation statements)

References 16 publications

(24 reference statements)

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“…All electronic parts of the generator were controlled and synchronized by an elaborated software, implemented to the Raspberry Pi PC with a Unix operating system. The single-bubble formation algorithm is based on the maximum bubble pressure principle [33] and was realized by programmable control of the pressure inside the system. Initially, the overpressure inside the system was adjusted according to the atmospheric and hydrostatic pressure.…”

Section: Methodsmentioning

confidence: 99%

Rupture of Wetting Films Formed by Bubbles at a Quartz Surface in Cationic Surfactant Solutions

Wiertel-Pochopien

Zawała

2019

Chem Eng & Technol

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Experimental studies were performed on the kinetics of the three-phase contact formation and bubble attachment to a quartz surface in solutions of a cationic surfactant of various concentrations. By tuning the distance between the singlebubble formation point and the quartz surface immersed in the solution, the influence of the state of the dynamic adsorption layer over a rising bubble on the mechanism of rupture of a wetting film formed was elucidated. Based on the unique methodology, allowing precise control over the initial degree of adsorption coverage at the detaching bubble, new evidence was found confirming the electrostatic character of the wetting film rupture in cationic surfactant solutions of low concentrations.

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Section: Methodsmentioning

confidence: 99%

Rupture of Wetting Films Formed by Bubbles at a Quartz Surface in Cationic Surfactant Solutions

Wiertel-Pochopien

Zawała

2019

Chem Eng & Technol

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“…Two different methods were used to generate single microbubbles: electrolysis for the generation of H 2 and O 2 bubbles (Gu et al, 2004) and a pressure pulse technique for the generation of CO 2 , air, and N 2 bubbles (Najafi et al, 2008). The electrolysis apparatus by Gu et al (2004) was adopted to generate small H 2 or O 2 bubbles.…”

Section: Methodsmentioning

confidence: 99%

“…This technique of bubble generation is reliable and reproducible. Bubbles of a very narrow size range can be produced using this method (Najafi et al, 2008). The distance between the micropipette tip and the collector surface was set sufficiently large (3 mm) to allow the bubble to reach its terminal velocity prior to colliding with the inclined collector surface.…”

mentioning

confidence: 99%

“…In this apparatus, the smaller bubbles generated by electrolysis were collected and coalesced in a bubble collection chamber. Once the bubble reached a desired size, it was expelled out from the chamber and rose in the liquid medium toward the collector surface.The pressure pulse technique was developed recently in our laboratory (Najafi et al, 2008). In this method, gas was injected through a submerged micropipette.…”

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confidence: 99%

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Measurement of sliding velocity and induction time of a single micro‐bubble under an inclined collector surface

Najafi

Masliyah

2008

Can J Chem Eng

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In this study, interactions between a gas bubble and a flat solid surface were investigated by determining two dynamic parameters, bubble sliding velocity underneath an inclined solid surface and induction time of the gas bubble attaching to the solid surface in aqueous solutions. A single micro-bubble was allowed to move vertically toward an inclined solid surface. After reaching its terminal velocity, the bubble approaches the inclined solid surface and slides underneath it. Complete trajectory of the bubble movement was monitored and recorded by a high-speed CCD video imaging system.Various types of gas bubbles (CO 2 , air, H 2 , and O 2 ) and solid surfaces such as bitumen-coated Teflon, hydrophobized and hydrophilic silica were used in sliding velocity and induction time measurements. The effect of water chemistry (industrial process water and de-ionized water) and surface heterogeneity on bubble sliding velocity and induction time was investigated. The results showed that the sliding velocity of micro-bubbles under an inclined solid surface is a strong function of water chemistry, gas type, temperature and hydrophobicity of the solid surface. This study provides relevant information on bubble-solid interactions that would assist in the understanding of bubble-solid attachment under diverse conditions. Dans cetteétude, on aétudié les interactions entre une bulle de gaz et une surface solide plane en déterminant deux paramètres dynamiques, la vitesse de glissement de bulle sous une surface de solides inclinée ainsi que le temps d'induction de l'attachement d'une bulle de gazà une surface solide en solution aqueuse. On a fait se déplacer une micro-bulle unique verticalement vers une surface solide inclinée. Après avoir atteint sa vitesse terminale, la bulle s'approche de la surface solide inclinée et glisse sous elle. La trajectoire complète de la bulle aété enregistrée par un système d'imagerie vidéo CCDà haute vitesse. Différents types de bulles de gaz (CO 2 , air, H 2 , et O 2 ) et de surfaces solides telles que du téflon enduit de bitume, de la silice hydrophobe et hydrophile, ontété utilisés dans les mesures de vitesse de glissement et de temps d'induction. L'effet de la chimie de l'eau (eau de procédés industriels et eau déminéralisée) et de l'hétérogénéité de la surface sur la vitesse de glissement et le temps d'induction aétéétudié. Les résultats montrent que la vitesse de glissement des micro-bulles sous une surface solide inclinée dépend fortement de la chimie de l'eau, du type de gaz, de la température et de l'hydrophobicité de la surface solide. Cetteétude fournit des informations pertinentes sur les interactions bulles-solides pouvant permettre de comprendre l'attachement bulles-solides dans des conditions diverses.Keywords: flotation, induction time, bubble sliding velocity, contact angle, bitumen INTRODUCTION B ubble and solid surface (collector) interactions play a major role in oil sands extraction, mineral processing, chemical and environmental industries (Dai et al., 1988). For example, in t...

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“…Yu et al proposed a model for bubble formation by dividing the process into three stages: an expansion stage, an elongation stage, and a pinch‐off stage. Terasaka and Tsuge , Najafi and Xu , and Rzasa proposed a revised nonspherical model to simulate bubble formation at a nozzle submerged in a cocurrently upward flowing liquid. The results of bubble shapes and growth curves of bubbles during formation, as calculated by their model, were in good agreement with experimental data.…”

Section: Introductionmentioning

confidence: 99%

Microbubble Formation in a Co‐flowing Liquid in a Microfluidic Chip

Zhang

Jiang

et al. 2017

Chem Eng & Technol

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Microbubble formation from a capillary tube surrounded by a co-flowing liquid (CFL) in a mechanically assembled microfluidic chip is investigated. The influences of gas pressure and liquid flow rate on the growth and detachment of the target microbubble are studied both experimentally and theoretically. A phenomenological theoretical model which consists of an expansion stage and a detachment stage is proposed based on a previous study to predict the detachment volume and formation time of microbubbles. The detachment distance is investigated experimentally in detail and later applied to the theoretical model. A MATLAB/ Simulink simulation model is built for the solution of the proposed theoretical model. Model predictions correlate well with the experimental data in the present study.

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Single micro-bubble generation by pressure pulse technique

Cited by 20 publications

References 16 publications

Rupture of Wetting Films Formed by Bubbles at a Quartz Surface in Cationic Surfactant Solutions

Rupture of Wetting Films Formed by Bubbles at a Quartz Surface in Cationic Surfactant Solutions

Measurement of sliding velocity and induction time of a single micro‐bubble under an inclined collector surface

Microbubble Formation in a Co‐flowing Liquid in a Microfluidic Chip

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