Interfacial studies on dissolved gas flotation of oil droplets for water purification

Oliveira, Roberto Carlos Goncalves de; González, Gaspar; Oliveira, José Farias de

doi:10.1016/s0927-7757(98)00890-5

Cited by 40 publications

(40 citation statements)

References 9 publications

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“…En effet, le chlorure de sodium augmente la tension superficielle, ce qui rigidifie l'interface gaz liquide et, par conséquent, limite la coalescence des bulles de gaz (KOIDE et al, 1968;MARRUCCI et NICODEMO, 1967;OLIVEIRA et al, 1999;STRICKLAND, 1980). La vitesse ascensionnelle des petites bulles est plus faible que celle des bulles plus larges (BRANDON et al, 1985).…”

Section: Résultats Et Discussionunclassified

Étude comparative de l’électrocoagulation et de la coagulation floculation vis-à-vis de la déstabilisation d’une émulsion d’huile de coupe

Aoudjehane

Rezzouk

Kellil

et al. 2010

rseau

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Ce travail a porté sur la déstabilisation d’une émulsion d’huile de coupe algérienne (Tasfalout 22/B) par électrocoagulation (EC) en batch en utilisant des électrodes de fer. L’efficacité du procédé est évaluée par la mesure de la turbidité. Une meilleure efficacité de déstabilisation est obtenue par une augmentation de la densité de courant de 50 à 350 A•m‑2 pour un temps d’électrolyse de 15 min et des concentrations en huile de coupe de 1 % (p/p), 2 % (p/p) et 4 %(p/p). Un rendement d’élimination en turbidité de 99 % a été obtenu pour une émulsion à 4 % (p/p), une densité de courant de 150 A•m‑2 et un temps d’électrolyse de 120 min.Le suivi de la cinétique de dissolution de l’électrode de fer sur une période de 120 minutes a montré qu’une même efficacité du procédé peut être obtenue par une diminution du temps d’électrolyse et une augmentation de la densité de courant.Une étude comparative des performances de l’électrocoagulation et de la coagulation-floculation au chlorure ferrique hydraté (FeCl3•6H2O), vis-à-vis de la déstabilisation d’une émulsion d’huile de coupe, a été réalisée. Elle a mis en évidence l’avantage de la coagulation-floculation pour l’émulsion à 1 % (p/p), pour les différentes densités de courant testées en électrocoagulation. Par contre, les rendements d’élimination pour les deux procédés sont sensiblement similaires pour les émulsions plus concentrées (2 % (p/p) et 4 % (p/p)), pour une densité de courant de 150 A•m‑2. Le pH des émulsions obtenu par les deux procédés après le traitement est différent. Le milieu reste alcalin dans l’électrocoagulation et il devient acide dans la coagulation floculation.This work focuses on the breakdown of an Algerian cutting oil emulsion (Tasfalout 22/B) by batch electrocoagulation (EC) using iron electrodes. The efficiency of the process was estimated from turbidity measurements. An improved efficiency of destabilization was obtained by increasing the current density from 50 to 350 A•m‑2, over an electrolysis time of 15 min and using cutting oil concentrations of 1% (w/w), 2% (w/w) and 4% (w/w). Monitoring of the kinetics of the electrode dissolution over a period of 120 min showed that a similar process efficiency was obtained by decreasing the electrolysis time and by increasing the current density. A 99% removal of turbidity was obtained for an emulsion of 4% (w/w) with a current density of 150 A•m‑2 and an electrolysis time of 120 min.A comparison of the performances of electrocoagulation and of coagulation-flocculation with hydrated ferric chloride (FeCl3•6H2O) processes was carried out, with respect to the destabilization of cutting oil emulsion. This comparison highlighted the advantage of the coagulation-flocculation process for the of 1% (w/w) emulsion at different electrocoagulation current densities. However, for a current density of 150 A•m‑2, the removal efficiency of both processes was similar for the emulsion with higher cutting oil concentrations (2% (w/w) and 4% (w/w)). The pH of the emulsion obtained by the two processes following treatmen...

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Section: Résultats Et Discussionunclassified

Étude comparative de l’électrocoagulation et de la coagulation floculation vis-à-vis de la déstabilisation d’une émulsion d’huile de coupe

Aoudjehane

Rezzouk

Kellil

et al. 2010

rseau

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“…Where P c is the collision probability, P a is adhesion probability that is determined by the thinning and rupturing of the interstitial film between bubble-drop and P s is stable aggregate probability (a function of contact angle value) (Oliveira et al, 1999). Collision probability depends on the concentration of oil droplets and gas bubbles as well as the projected areas of the droplets and gas bubbles (Walsh, 2012).…”

Section: Oil Droplet-bubble Attachmentmentioning

confidence: 99%

“…Higher concentrations and surface area leads to a higher collision rate (Bahadori et al, 2013). As collision efficiency is directly proportional to droplet diameter and inversely proportional to bubble diameter, better collision can be realized by injecting finer gas bubbles (Oliveira et al, 1999). A Sweep Factor, one of the design parameters used in gas flotation, defines the number of times per minute gas bubbles will contact with any particular volume element in the flotation cell (Juniel et al, 2004;Lee and Frankiewicz, 2004;Walsh, 2012).…”

Section: Oil Droplet-bubble Attachmentmentioning

confidence: 99%

“…It has been reported that droplet-bubble adhesion happens when a film thickness of 0.1 mm is reached. At this point, the film ruptures due to a stronger intermolecular force between the droplet and bubble which eventually forms a dropletbubble aggregate (Oliveira et al, 1999). Rawlins (C. Hank Rawlins, 2011 explained the following four possible droplet-bubble adhesion mechanisms:-(i) Direct impingement with full or partial encapsulation by chemical adhesion.…”

Section: Oil Droplet-bubble Attachmentmentioning

confidence: 99%

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An overview of oil–water separation using gas flotation systems

2016

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“…According to the appropriate literature [17][18][19], the oil droplets in oily wastewater are normally stabilized as an oil-in-water emulsion, having a median droplet diameter usually in the range of 3-50 lm. A range of air bubbles is beneficial because the smaller bubbles can capture the smaller oil droplets and the larger ones, the larger droplets [26][27][28].…”

Section: Size Distribution Of Air Bubblesmentioning

confidence: 99%

Study of Air‐Liquid Flow Patterns in Hydrocyclone Enhanced by Air Bubbles

Bai

Wang

2008

Chem Eng & Technol

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In order to improve the oil-water separation efficiency of a hydrocyclone, a new process utilizing air bubbles has been developed to enhance separation performance. Using the two-component phase Doppler particle analyzer (PDPA) technique, the velocities of two phases, air and liquid, and air bubble diameter were measured in a hydrocyclone. The air-liquid mixing pump can produce 15 to 60 lm-diameter air bubbles in water. There is an optimum air-liquid ratio for oil-water separation of a hydrocyclone enhanced by air bubbles. An air core occurs in the hydrocyclone when the air-liquid ratio is more than 1 %. The velocities of air bubbles have a similar flow pattern to the water phase. The axial and tangential velocity differences of the air bubbles at different air-liquid ratio are greater near the wall and near the core of the hydrocyclone. The measured results show that the size distribution of the air bubbles produced by the air-liquid mixing pump is beneficial to the process where air bubbles capture oil droplets in the hydrocyclone. These studies are helpful to understand the separation mechanism of a hydrocyclone enhanced by air bubbles.

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Interfacial studies on dissolved gas flotation of oil droplets for water purification

Cited by 40 publications

References 9 publications

Étude comparative de l’électrocoagulation et de la coagulation floculation vis-à-vis de la déstabilisation d’une émulsion d’huile de coupe

Étude comparative de l’électrocoagulation et de la coagulation floculation vis-à-vis de la déstabilisation d’une émulsion d’huile de coupe

An overview of oil–water separation using gas flotation systems

Study of Air‐Liquid Flow Patterns in Hydrocyclone Enhanced by Air Bubbles

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