The effect of pH on experimental and simulation results of transient drop size distributions in stirred liquid–liquid dispersions

Gäbler, A.; Wegener, M.; Paschedag, Anja R.; Kraume, Matthias

doi:10.1016/j.ces.2005.10.072

Cited by 57 publications

(55 citation statements)

References 24 publications

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“…With addition of sodium chloride and therefore rising ionic strength, the coalescence inhibition was reduced and the drop sizes in the system increased, which agrees with the DLVO theory. The decrease of the drop size distribution at high pH values in a stirred tank is also described by Gäbler et al (2006) and Kraume et al (2004). The authors explain this effect by an increasing coalescence inhibition with higher pH values.…”

Section: Introductionmentioning

confidence: 54%

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Coalescence efficiency model including electrostatic interactions in liquid/liquid dispersions

Kamp¹,

Kraume²

2015

Chemical Engineering Science

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The drop size distribution is an essential process variable in liquid/liquid systems and relevant in many technical applications. It can be described by population balance equations. A coalescence efficiency model was developed to be able to describe the well-known coalescence inhibition due to changing pH value or salt concentration. The model includes the attractive van der Waals and repulsive electrostatic force according to the DLVO theory into the population balance equation framework. This DLVO model can extend existing simulations in a straightforward manner due to a conceptual implementation. Moreover, zeta potential measurements were performed and the model was applied to simulate experiments in a stirred tank. Hence, the drop size distribution could be predicted well with changing pH value. The results are discussed in comparison to simulations with existing models in literature.

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Section: Introductionmentioning

confidence: 54%

“…The volume-related PBE for this batch reactor describing the time dependent number density function ( , ) of drops with diameter dp becomes (Attarakih et al, 2004;Gäbler et al, 2006;Liao and Lucas, 2009):…”

Section: Numerical Investigations and Parameter Estimationmentioning

confidence: 99%

Coalescence efficiency model including electrostatic interactions in liquid/liquid dispersions

Kamp¹,

Kraume²

2015

Chemical Engineering Science

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“…The essential characteristic of an emulsion is its drop size distribution that drops size distribution and dynamics of their evolution are important characteristics of such dispersions as they are related to the rate of mass transfer and chemical reactions that may occur in a process (Balmelli et al, 2000;Gabler et al, 2006;Sechremeli et al, 2006). In solvent extraction processes for instance, the interfacial area of dispersion controls the mass transfer rate and is a key parameter for the design and scaling-up of gravity settlers that ensure the ultimate liquid phases separation.…”

Section: Introductionmentioning

confidence: 99%

The effects of impeller speed and holdup on mean drop size in a mixer settler with spiral‐type impeller

Khakpay

Abolghasemi

2010

Can J Chem Eng

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An experimental investigation has been carried out in order to analyse the drop size distributions of liquid-liquid dispersion in a single stage mixer settler extractor. In this paper, the effects of the impeller speed and the holdup on mean drops size, D 32 , have been investigated. D 32 was decreased with an increase in the impeller speed. Furthermore, D 32 was increased with an increase in the holdup. In addition, a new and modified correlation was established based on these results. The average absolute relative deviation is 3.36%.Uneétude expérimentale aété effectuée pour analyser la répartition de la taille des gouttes pour la dispersion liquide-liquide dans un extracteurdécanteur-mélangeuràétage unique. Dans cet article, onétudie les effets de la vitesse d'agitation et la retenue d'une goutte de taille moyenne, D32. D32 diminuait avec l'augmentation de la vitesse d'agitation. De plus, D32 augmentait avec l'augmentation de la retenue. Par ailleurs, une corrélation nouvelle et modifiée aété mise en place en se basant sur ces résultats. L'écart relatif absolu moyen est de 3,36%.

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“…The range of drops used in this work is within the conditions of circulating drops, since the values of dimensionless group H defined in the model by Grace et al [29] are in the range of 13.9-35.5 (2< H<59.3), corresponding to circulating drops: (10) where Eö=gd 2 ∆ρ/γ is the Eötvös number, M=gµ c 4 ∆ρ/ρ c 2 γ 3 is the Morton number, µ c is the continuous phase viscosity, µ W is the viscosity of water at 4 o C and γ is the interfacial tension. The value of 59.3 for H corresponds, approximately, to the transition between non-oscillating and oscillating drops.…”

Section: Resultsmentioning

confidence: 99%

“…It has been presumed that the origin of the negative charge at the organic-water interface is the adsorbed hydroxyl ions from the aqueous phase. With increasing pH, adsorption of hydroxyl ion increases, widening the surface charge layer around the drops [7][8][9][10]. The reduction of interfacial tension with pH can be attributed to this problem.…”

Section: Introductionmentioning

confidence: 99%

Modelling mass transfer coefficient for liquid-liquid extraction with the interface adsorption of hydroxyl ions

Saien

Daliri

2009

Korean J. Chem. Eng.

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A combined model was used for prediction of overall mass transfer coefficient of drops in the liquid-liquid extraction process, prone to the deleterious effect of adsorbed hydroxyl ions onto the interface. The importance is due to the use of different pH waters as aqueous phase. The work is based on single drop experiments with a chemical system of toluene-acetone-water where the pH of the continuous aqueous phase was within the range 5.5-8, appropriate to most industrial waters, and can lead to rigid behavior of circulating drops. The combined model in conjunction with the correlation developed here for the ratio of interfacial velocity to drop terminal velocity that links the film mass transfer coefficients of both sides can be used satisfactorily for design purposes. This model gives a maximum relative deviation of less than ±10% for the mass transfer directions of dispersed to continuous phase and vice versa.

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The effect of pH on experimental and simulation results of transient drop size distributions in stirred liquid–liquid dispersions

Cited by 57 publications

References 24 publications

Coalescence efficiency model including electrostatic interactions in liquid/liquid dispersions

Coalescence efficiency model including electrostatic interactions in liquid/liquid dispersions

The effects of impeller speed and holdup on mean drop size in a mixer settler with spiral‐type impeller

Modelling mass transfer coefficient for liquid-liquid extraction with the interface adsorption of hydroxyl ions

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