Prediction of enhancement factor for mass transfer coefficient in regular packed liquid–liquid extraction columns

Abstract

Mass transfer coefficients are one of the most important parameters for the design of liquid-liquid extraction columns. The mass transfer coefficients of single drops in a pilot structured packed column have been measured using toluene/acetic acid/water and n-butyl acetate/acetic acid/water systems. Current research shows that theoretical models have failed to predict mass transfer coefficient precisely and are not reliable for design. In this work an empirical correlation for prediction of enhancement factor is developed. Dispersed phase mass transfer coefficients predicted by the proposed correlation are in good compatibility with experimental results.Les coefficients de transfert de masse figurent parmi les paramètres les plus importantsà prendre en compte lors de la conception de colonnes d'extraction liquide-liquide. Les coefficients de transfert de masse de chaque goutte dans une colonneà garnissage structuré pilote ontété mesurés grâceà des systèmesà base de toluène/d'acide acétique/d'eau et d'acétate de n-butyle/d'acide acétique/et d'eau. La comparaison entre les modèles théoriques et les résultats expérimentaux de coefficients de transfert de masse a montré que ces modèles ne sont pas assez précis pour etre appliquésà la conception. Dans cette recherche, les facteurs d'accentuation du coefficient de diffusion ontété déterminés expérimentalement et une corrélation empirique aété atteinte pour le facteur d'accentuation. Les coefficients de transfert de masse de la phase dispersée qui avaitété prévus grâceà la corrélation proposée s'harmonisent bien aux résultats des expériences.

The influence of silica nanoparticles on hydrodynamics and mass transfer in spray liquid–liquid extraction column

“…Since the results of the present research showed that nanoparticles do not show significant influence on the hydrodynamic parameters such as interfacial area, it seems that the effect of nanoparticles on extraction efficiency is due to the internal turbulence of drops. The slope of equilibrium curve (m), within the used concentration range in this work is low (m $ 0.075) and mass transfer resistance exists mainly in the organic phase [47][48][49]. It can be justified, considering the Whitman two film theory, where the overall mass transfer resistance is obtained from sum of the local mass transfer resistance in phases, i.e.…”

Drop behaviour characteristics in different operating regimes in an L‐shaped pulsed sieve‐plate column

“…On the other hand, when there is mass transfer from the continuous phase to the dispersed phase, smaller drops are produced in comparison to the same condition without mass transfer. In fact, because of the consequent interfacial tension gradient, the interface movement of the drop and the inner circulation generated into the drop gain the same direction . Therefore, this mass transfer path leads to increase on the interface deformations, consequent deformation of drops, and higher drop breakage.…”

“…In fact, because of the consequent interfacial tension gradient, the interface movement of the drop and the inner circulation generated into the drop gain the same direction. [44][45][46] Therefore, this mass transfer path leads to increase on the interface deformations, consequent deformation of drops, and higher drop breakage.…”

Mass Transfer from Single Drops and the Influence of Temperature

“…Therefore, mass transfer resistance exists totally in the dispersed phase, that is, K od ≈ k d . 8,20 In an attractive method in modeling which has been adopted, the molecular diffusivity (D d ) in Newman's equation: where is the enhancement factor and empirical correlations are presented to predict its value. Sherwood et al 21 were first to use this approach, pointing out that the equation for radial diffusion in a rigid sphere 22 may be used for mass transfer in all kinds of drops if the molecular diffusivity is multiplied by an empirical factor ( ).…”