Correlation of Ternary Liquid-Liquid Equilibria

Vriens, G. N.; Medcalf, E. C.

doi:10.1021/ie50521a060

Cited by 33 publications

(13 citation statements)

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“…The application was tested on a set of 270 zeotropic and azeotropic systems of homogeneous binary solutions and 30 non‐homogeneous systems. In addition to the VLE data, values of the excess properties ( v E and h E ) have been used and, also, LLE data of the system studied, extracted from the literature,…”

Section: Results Of the Testmentioning

confidence: 99%

A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE

2017

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This work forms part of a broader study that describes a methodology to validate experimental data of phase equilibria for multicomponent systems from a thermodynamic‐mathematical perspective. The goal of this article is to present and justify this method and to study its application to vapor–liquid equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE), obtained under isobaric/isothermal conditions. A procedure based on the Gibbs‐Duhem equation is established which presents two independent calculation paths for its resolution: (a) an integral method and (b) a differential method. Functions are generated for both cases that establish the verification or consistency of data, δψ for the integral test and δζ for the differential approach, which are statistically evaluated by their corresponding average values [ δtrueψ¯, δtrueζ¯], and the standard deviations [ strue(δψtrue), strue(δζtrue)]. The evaluation of these parameters for application to real cases is carried out using a set of hypothetical systems (with data generated artificially), for which the values are adequately changed to determine their influence on the method. In this way, the requirements of the proposed method for the data are evaluated and their behavior in response to any disruption in the canonical variables (p,T, phase compositions). The conditions for thermodynamic consistency of data are: δtrueψ¯<2, strue(δψtrue)<0.2, δtrueζ¯<5, and s(δξ)<0.2. In systems with VLLE, in addition to the previous criteria, must occur that: δxLLE<0.05 and δTLLE<0.5 K. The new proposed method has been tested with a set of 300 experimental binary systems, biphasic and triphasic, obtained from published bibliography, and the results are compared with those of other tests commonly used for testing thermodynamic consistency. The results show that the greater rigor of the proposed method is mainly due to the simultaneous verification of various independent variables. As a result, the conditions for the new test are verified for fewer systems than using other tests mentioned in the literature (i.e., Fredenslund‐test and direct of Van Ness). Its unique application is sufficient to ensure the consistency of experimental data, without using other tests. © 2017 American Institute of Chemical Engineers AIChE J, 2017

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Section: Results Of the Testmentioning

confidence: 99%

A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE

2017

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“…The NRTL-HOC and UNIQUAC-HOC models showed better fits than did the Wilson-HOC model. The reason is that the binary system comes about as close to separating into two phases as is possible without actually doing so at the boiling point, 7 whereas the Wilson model is appropriate only for the miscible system.…”

Section: Resultsmentioning

confidence: 99%

“…Vriens measured the VLE data over the range of 6.6 to 95.5 mass % of 2-methylpyridine for the binary system with a modified Othmer still at 101.32 kPa and reported that the azeotropic values are 94.8 °C, 53.3 mass % of 2-methylpyridine. 7 Jiang et al measured the VLE data of the binary system with a modified Rose still at 1 atm, and they reported that the azetropic temperature and composition were 94.5 °C, 52.5 mass % of 2methylpyridine. 8 However, the correlated results of VLE data in the above-mentioned literature were that there existed an immiscible phenomenon near the azeotropic area, which is in contradiction with reality.…”

Section: Introductionmentioning

confidence: 99%

“…It had also been reported that 2-methylpyridine and water formed the minimum-boiling azeotrope. Vriens measured the VLE data over the range of 6.6 to 95.5 mass % of 2-methylpyridine for the binary system with a modified Othmer still at 101.32 kPa and reported that the azeotropic values are 94.8 °C, 53.3 mass % of 2-methylpyridine . Jiang et al measured the VLE data of the binary system with a modified Rose still at 1 atm, and they reported that the azetropic temperature and composition were 94.5 °C, 52.5 mass % of 2-methylpyridine .…”

Section: Introductionmentioning

confidence: 99%

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Isobaric Vapor–Liquid Equilibrium Data for the Binary System of Water + 2-Methylpyridine at 101.3, 60.0, and 20.0 kPa

et al. 2017

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Isobaric vapor−liquid equilibrium (VLE) data for the binary system of water + 2-methylpyridine were determined by using Fisher VLE 602 equipment at 101.3, 60.0, and 20.0 kPa to assist with the design of the separation process by distillation. All of the binary data at different pressures were considered to be thermodynamically consistent according to Wisniak's area and point test. The results showed that the binary system at all three pressures formed the minimum boiling azeotropes and exhibited a positive deviation from Raoult's law. The binary VLE data were correlated by using NRTL-HOC, UNIQUAC-HOC, and Wilson-HOC models with minor deviations, and the result showed that all three models were in good agreement with the experimental data. The azeotropic temperatures and compositions at 101.3, 60.0, and 20.0 kPa were determined by the NRTL-HOC model, respectively, which showed that the azeotropic composition of 2-methylpyridine tended to decrease with the decline in system pressure.

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“…These aggregates have an optimal volume set by steric constraints due to surfactant head-group area or "surface charge regulation". [3][4][5] However, strange observations dating back to the early XXth century about membrane enzyme reactions in lipid-less media, 6 non-linear effects in evaporation of ternary mixtures, 7 the polar paradox in oxidation rates of ternary uids 8 as well as unexplained "single phase" ternary solutions that contain ethanol 9 led to the proposition in the seventies by the group of Barden 10 that "surfactant-less microemulsions" should go beyond a nice name to some strange unexplained properties of some homogeneous ternary uids that can be reversibly phase separated by simple centrifugation, 10 but correspond to a thermodynamic equilibrium in the phase diagram. The existence of SFME was considered by most people as a sort of urban legend, mainly due to the tautological argument that all known micelles contained surfactants, so surfactant-less micelles or microemulsions should not exist.…”

Section: Introductionmentioning

confidence: 99%

Emergence of surfactant-free micelles from ternary solutions

et al. 2014

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Curious effects ranging from enzyme activity to anomalies in evaporation rates that have been known for over fifty years suggest the existence and thermodynamic stability of surfactant-free micelles. Only recently, joint X-ray, light and neutron scattering experiments have demonstrated that aggregates and bulk pseudo-phases coexist in presumably normal solutions, in which a water insoluble component is solubilized in a certain domain of concentration of a hydrotrope component like ethanol. Nevertheless, nothing is known about the molecular-level shape and structure of such aggregates. In this work we characterize mixtures of octanol, ethanol, and water by molecular dynamics simulations. For compositions in the "pre-ouzo" region (close to the single phase stability limit) we observe micelle-like aggregates that are clearly distinct from simple critical density fluctuations. We define an ethanol partition in the pseudo-phase from an integral of the van der Waals dispersion energy term. From this partition, octanol-rich aggregates swollen with ethanol appear with an emerging interface. Ethanol is present in the water pseudo-phase with an exponential decay similar to the one predicted by Marcelja and Radic forty years ago.

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Correlation of Ternary Liquid-Liquid Equilibria

Cited by 33 publications

References 1 publication

A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE

A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE

Isobaric Vapor–Liquid Equilibrium Data for the Binary System of Water + 2-Methylpyridine at 101.3, 60.0, and 20.0 kPa

Emergence of surfactant-free micelles from ternary solutions

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