Ternary mass transfer in liquid-liquid extraction

Krishna, Rajamani; Low, Chong Yu; Newsham, D.M.T.; Olivera-Fuentes, Claudio; Standart, G.

doi:10.1016/0009-2509(85)85003-x

Cited by 19 publications

(13 citation statements)

References 20 publications

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“…(21)) suggests that two mass diffusion modes should occur. This expectation is further supported by liquid-liquid extraction experiments [24] which could only be interpreted if both mass diffusion modes were taken into account. By Onsager's regression hypothesis these modes should also occur in DLS measurements.…”

Section: Application To Experimental Datamentioning

confidence: 71%

On the interpretation of ternary diffusion measurements in low-molecular weight fluids by dynamic light scattering

Bardow

2007

Fluid Phase Equilibria

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Section: Application To Experimental Datamentioning

confidence: 71%

On the interpretation of ternary diffusion measurements in low-molecular weight fluids by dynamic light scattering

Bardow

2007

Fluid Phase Equilibria

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“…15 The A-C and B-D equilibration trajectories, determined experimentally in a stirred two-compartment Lewis stirred cell, are observed to follow curvilinear paths. 16 The use of eqn (2) cannot accurately model the observed equilibration trajectories. Whether the equilibration process follows a straight-line path or a serpentine path is of crucial importance if we wish to form metastable dispersions.…”

Section: Phase Stability and Diffusion In Non-ideal Liquid Mixturesmentioning

confidence: 99%

“…This conclusion would be erroneous in the event that the equilibrated composition lies on the spinodal curve. As proof, let us investigate inter-diffusion in glycerol-acetone-water mixtures of different compositions that equilibrate to a composition that 16 In the 2D composition space, the trajectory is linear, at a tangent to the binodal curve; see Fig. 16a.…”

mentioning

confidence: 99%

Uphill diffusion in multicomponent mixtures

2015

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Molecular diffusion is an omnipresent phenomena that is important in a wide variety of contexts in chemical, physical, and biological processes. In the majority of cases, the diffusion process can be adequately described by Fick's law that postulates a linear relationship between the flux of any species and its own concentration gradient. Most commonly, a component diffuses down the concentration gradient. The major objective of this review is to highlight a very wide variety of situations that cause the uphill transport of one constituent in the mixture. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of its partner species. Such coupling effects often arise from strong thermodynamic non-idealities. For a quantitative description we need to use chemical potential gradients as driving forces. The transport of ionic species in aqueous solutions is coupled with its partner ions because of the electro-neutrality constraints; such constraints may accelerate or decelerate a specific ion. When uphill diffusion occurs, we observe transient overshoots during equilibration; the equilibration process follows serpentine trajectories in composition space. For mixtures of liquids, alloys, ceramics and glasses the serpentine trajectories could cause entry into meta-stable composition zones; such entry could result in phenomena such as spinodal decomposition, spontaneous emulsification, and the Ouzo effect. For distillation of multicomponent mixtures that form azeotropes, uphill diffusion may allow crossing of distillation boundaries that are normally forbidden. For mixture separations with microporous adsorbents, uphill diffusion can cause supra-equilibrium loadings to be achieved during transient uptake within crystals; this allows the possibility of over-riding adsorption equilibrium for achieving difficult separations. Key learning points(1) Coupling effects in mixture diffusion may cause uphill transport of a component (2) Uphill diffusion results in transient overshoots and serpentine equilibration trajectories (3) Non-ideal phase equilibrium thermodynamics is often the major source of diffusional coupling effects (4) Chemical potential gradients are the proper driving forces for diffusion (5) Uphill transport can be exploited to achieve difficult and unusual separations

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“…As shown by many examples [12], the GMS confirm experimentally observed phenomena of multicomponent systems which are (i) reverse diffusion (diffusion of a component against its concentration gradient), (ii) osmotic diffusion (transport of a component in the absence of a concentration gradient), and (iii) diffusion barrier (no transport of a component although its concentration gradient is nonzero). Since these diffusional coupling effects are significant for liquid-liquid extraction systems as demonstrated experimentally and theoretically by Krishna et al [13] and others [14,15], the GMS seem to be sufficient for the simulation of multicomponent extraction processes. Following the detailed survey of Taylor and Krishna [16], a brief outline of the model equations used in this work is given.…”

Section: Maxwell-stefan Relations For Mass Transfer Across Fluid Intementioning

confidence: 97%

Multicomponent Mass Transfer Model for Supercritical Extraction: Application to Isopropyl Alcohol Production

et al. 2009

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A multicomponent mass transfer model based on the generalized Maxwell-Stefan equations (GMS) for an extraction process with supercritical fluids is presented. The solution is obtained from the differential film model equations rather than from an explicit expression for the fluxes. The approach presented here also provides concentration profiles along the diffusion path length, which allow rigorous consideration of the dependence of mass transfer coefficients and thermodynamic factors on concentration, if desired. The volume translated Peng-Robinson equation of state is used along with a g E mixing rule (g E -molar excess Gibbs free energy) in order to account for strongly nonideal thermodynamics that necessarily arise in unstable liquid mixtures. The results show strong diffusional coupling effects for the system under consideration, propene (1)-isopropyl alcohol (2)-water (3). Finally, we demonstrate how diffusional coupling may provide options for process intensification.

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Ternary mass transfer in liquid-liquid extraction

Cited by 19 publications

References 20 publications

On the interpretation of ternary diffusion measurements in low-molecular weight fluids by dynamic light scattering

On the interpretation of ternary diffusion measurements in low-molecular weight fluids by dynamic light scattering

Uphill diffusion in multicomponent mixtures

Multicomponent Mass Transfer Model for Supercritical Extraction: Application to Isopropyl Alcohol Production

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