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# Fluid Phase Equilibria (v.259, #1)

VII Iberoamerican conference on phase equilibria and fluid properties for process design by Luis A. Galicia-Luna; Dominique Richon; Theo W. de Loos (

*pp. 1-2*).

Nanoporous carbon membranes for separation of nitrogen and oxygen: Insight from molecular simulations by Gaurav Arora; Stanley I. Sandler (

*pp. 3-8*).

_{2}and N

_{2}in nanoporous carbon membranes. Two different representation of the amorphous nanoporous membrane structure are used; the hypothetical C

_{168}Schwarzite and a single wall carbon nanotube with a constriction. By comparing the results obtained from empirical planar graphite potential and an ab initio-based potential, the effect of carbon curvature and the presence of non-hexagonal carbon rings in C

_{168}Schwarzite is also investigated. It is found using either force field, that the energetic effect alone cannot explain the experimental observations. However, simulations performed using carbon nanotube with a constriction show that the size or entropic effect can be dominant. In particular, it is shown that an appropriate size constriction can result in large transport resistance to nitrogen while letting oxygen to pass through at a much higher rate, even though these gases have very similar molecular sizes and interaction energetics.

**Keywords:** Nanoporous carbon sieves; Membrane; Adsorption; Diffusion; Molecular dynamics; Monte Carlo; Nanotubes; Nitrogen; Oxygen; Ideal selectivity

Effective intermolecular potentials in theoretical thermodynamics of pure substances and solutions by Fernando del Río; Orlando Guzmán; J. Eloy Ramos; Benjamín Ibarra-Tandi (

*pp. 9-22*).

*T*

_{c},

*V*

_{c}and

*P*

_{c}). Most gaseous-phase properties are obtained within estimated experimental errors. The molecular features whose effects have been incorporated into the ANC effective potentials are overlap, dispersion, electrostatic (dipolar and quadrupolar) and many-body interactions, and steric features such as elongation Applications to a selection of non-polar substances noble gas molecules, diatomics and light alkanes highlight the main features of the theory. New results include Gibbs ensemble Monte Carlo simulations of ANC fluids, an effective potential to account for many-body forces, prediction of critical temperatures and volumes, and we also prove a general relation satisfied by the critical temperatures of many substances.

**Keywords:** Effective interactions; Real fluids; Critical properties; Many-body forces; Molecular models

High-pressure vapor–liquid equilibria for CO

_{2}+alkanol systems and densities of

*n*-dodecane and

*n*-tridecane by Octavio Elizalde-Solis; Luis A. Galicia-Luna; Luis E. Camacho-Camacho (

*pp. 23-32*).

_{2}+alkanol systems. Equilibrium measurements for the CO

_{2}+1-propanol system were performed from 344 to 426K. For the case of the CO

_{2}+2-propanol system, measurements were made from 334 to 443K, and for the CO

_{2}+1-butanol were obtained from 354 to 430K. VLE data were correlated with the Peng–Robinson equation of state using the classical and the Wong–Sandler mixing rules. Moreover, compressed liquid densities for the

*n*-dodecane and

*n*-tridecane were obtained via a vibrating tube densitometer at temperatures from 313 to 363K and pressures up to 25MPa. The Starling and Han (BWRS), and The five-parameter Modified Toscani-Swarcz (MTS) equations were used to correlate them. The experimental density data were compared with those from literature, and with the calculated values obtained from available equations for these

*n*-alkanes.

**Keywords:** Vapor–liquid equilibria; Density; Alkanes; Alkanols; Carbon dioxide

Volumetric properties of the boldine+alcohol mixtures at atmospheric pressure from 283.15 to 333.15K by Christophe Coquelet; Alain Valtz; Dominique Richon; Juan C. de la Fuente (

*pp. 33-38*).

*n*-C

_{1}to

*n*-C

_{6},

*n*-C

_{8}, and isopropanol. The density of these systems has been found an increasing function of the boldine composition. A new methodology based on density data of solutions of solid solutes with normal alcohols is described in order to determine solid molar volume of pure solutes. This methodology was validated with pure solid naphthalene molar volumes data at 298.15K, with an average uncertainty of 6%.

**Keywords:** Binary system; Boldine; *n*; -Alcohols; Isopropanol; Density; Partial molar volume; Estimation of solid density; New method

Thermodynamics of mixtures containing amines by M. Fernández Regúlez; I. Mozo; J.A. González; I. García de la Fuente; J.C. Cobos (

*pp. 39-44*).

*o*-toluidine with heptane, octane, nonane, decane or dodecane have been determined visually. All the curves show an upper critical solution temperature (UCST), which increases with the chain length of the alkane. The bimodal curves have a rather flat horizontal top and their symmetry depends on the chain length of the alkane. For the studied systems, interaction parameters in the framework of the DISQUAC model are reported. DISQUAC represents the coordinates of the critical points in the correct range of temperature and composition.

**Keywords:** *o*; -Toluidine; Alkanes; LLE; Upper critical solution temperatures; DISQUAC

New isothermal vapor–liquid equilibria for the CO

_{2}+

*n*-nonane, and CO

_{2}+

*n*-undecane systems by Luis E. Camacho-Camacho; Luis A. Galicia-Luna; Octavio Elizalde-Solis; Zenaido Martínez-Ramírez (

*pp. 45-50*).

_{2}+

*n*-nonane and CO

_{2}+

*n*-undecane systems were obtained by using a 100-cm

^{3}high-pressure titanium cell up to 20MPa at four temperatures (315, 344, 373, and 418K). The apparatus is based on the static-analytic method; which allows fast determination of the coexistence curve. For the CO

_{2}+

*n*-nonane system, good agreement was found between the experimental data and those reported in literature. No literature data were available for the CO

_{2}+

*n*-undecane system at high temperature and pressure. Experimental data were correlated with the Peng–Robinson equation of state using the classical and the Wong–Sandler mixing rules.

**Keywords:** Vapor–liquid equilibria; Equation of state; Static-analytic method

Study of the behaviour of the azeotropic mixture ethanol–water with imidazolium-based ionic liquids by Noelia Calvar; Begoña González; Elena Gómez; A. Domínguez (

*pp. 51-56*).

_{6}mim][Cl]) and for the corresponding binary systems containing the ionic liquid (ethanol+[C

_{6}mim][Cl], water+[C

_{6}mim][Cl]) were carried out at 101.300kPa. VLE experimental data of binary and ternary systems were correlated using the NRTL equation. In a previous work [N. Calvar, B. González, E. Gómez, A. Domínguez, J. Chem. Eng. Data 51 (2006) 2178–2181], the VLE of the ternary system ethanol+water+[C

_{4}mim][Cl] was determined and correlated, so we can study the influence of different ionic liquids in the behaviour of the azeotropic mixture ethanol–water.

**Keywords:** Ethanol; Water; Ionic liquid; Binary; NRTL

Isobaric vapor–liquid equilibria of 1,1-dimethylethoxy-butane+methanol or ethanol+water at 101.32kPa by Alberto Arce; Alberto Arce Jr.; José Manuel Martínez-Ageitos; Ana Soto (

*pp. 57-65*).

**Keywords:** VLE; BTBE; Alcohols; Water

Isobaric vapor–liquid and vapor–liquid–liquid equilibrium data for the water–ethanol–hexane system by V. Gomis; A. Font; R. Pedraza; M.D. Saquete (

*pp. 66-70*).

**Keywords:** Vapor–liquid equilibria; Vapor–liquid–liquid equilibria; Ethanol; Hexane

Quinary liquid–liquid equilibria for mixtures of nonane+undecane+two pairs of aromatics (benzene/toluene/

*m*-xylene)+sulfolane at 298.15 and 313.15K by Rílvia S. Santiago; Martín Aznar (

*pp. 71-76*).

*m*-xylene+sulfolane) and (nonane+undecane+toluene+

*m*-xylene+sulfolane) at 298.15 and 313.15K and ambient pressure. The experimental LLE data were determined by using a jacketed glass cell with temperature controlled. The quantitative analysis was performed by using a Varian gas chromatograph equipped with a flame ionization detector and a SPB™-1 column. The experimental quinary liquid–liquid equilibrium data have been satisfactorily correlated by using NRTL and UNIFAC-LLE models. The calculated values based on the NRTL model were found to be in a better agreement with the experiment than those based on the UNIFAC-LLE model.

**Keywords:** Quinary mixtures; Liquid–liquid equilibria; Sulfolane; Activity coefficient models

Bubble-point measurements for the system CO

_{2}+aqueous ethanol solutions of boldo leaf antioxidant components (boldine and catechin) at high pressures by Juan C. de la Fuente; Gonzalo Núñez; José M. del Valle (

*pp. 77-82*).

_{2}mixtures were determined visually using a synthetic method in an experimental apparatus that included a variable-volume equilibrium cell. Tested solutes included boldo leaf tincture, a boldine+catechin mixture, pure boldine, and pure catechin. Uncertainties in bubble-point pressures were estimated to be <5%, based on comparisons with literature values and replicate measurements. The largest effect we observed was an average increase of 205% in the bubble-point pressure when decreasing the ethanol-to-water ratio from 63:37 to 37:63 (w/w). The bubble-point pressure increased 11% when increasing the temperature from 313 to 343K, and decreased 8.2% when increasing the concentration of solids from 400 to 1500ppm. The bubble-point pressure was higher for boldo leaf tincture than for a boldine+catechin mixture having the same boldine-to-catechin weight ratio, but this was partially due to a lower content of solids in the tincture. On the other hand, bubble-point pressures of the boldine+catechin mixture were marginally (0.33%) higher than the weighed average of the bubble-point pressures for pure boldine and pure catechin.

**Keywords:** Antisolvent precipitation; Aqueous ethanol extract; Boldine; Boldo leaf antioxidants; Bubble-point pressure; Catechin; Supercritical CO; _{2}

Liquid–liquid equilibrium of ternary systems containing nicotine by Raquel M. Maduro; Martín Aznar (

*pp. 83-88*).

**Keywords:** Liquid–liquid equilibrium; Experimental; Nicotine; Modeling; NRTL; UNIQUAC

Modeling high-pressure densities at wide temperature range with volume scaling: Cyclohexane+

*n*-hexadecane mixtures by Josinira A. Amorim; Osvaldo Chiavone-Filho; Márcio L.L. Paredes; Krishnaswamy Rajagopal (

*pp. 89-98*).

*n*-hexadecane mixtures at a wide temperature range was modeled with several classical equations of state (EOS) and correlative models. A modification for softening the co-volume and another for a volume scaling of the Peng–Robinson EOS (VS-PR) were proposed. The VS-PR model is able to correlate the pure component experimental data employing only five adjustable parameters, with root-mean-square deviation (RMSD) between calculated and experimental densities essentially within the experimental error. This result is superior to widely used approaches, i.e., a six parameter Tait model and six parameter volume translations (temperature and pressure dependent) for Peng–Robinson and Patel–Teja EOS. The VS-PR model also represents well the isobaric thermal expansion and the isothermal compressibility coefficients of the pure cyclohexane, a small naphthenic substance as well as a long chain

*n*-alkane hydrocarbon,

*n*-hexadecane. When modeling the mixture data, the use of VS-PR model of pure components along with the Redlich–Kister expansion, truncated at the first term, the density was correlated within a RMSD only 60% greater than the experimental error. The proposed model is able to accurately represent all the tested mixture data with a relatively small number of parameters.

**Keywords:** High-pressure density; Equation of state modeling; Thermal expansion coefficient; Isothermal compressibility; Volume scaling

New volume translation for cubic equations of state by S. Laugier; F. Rivollet; D. Richon (

*pp. 99-104*).

*PVT*data, no new adjustment is required to treat mixtures provided pure component weights are available.Pure component weights related to neural networks are conveniently adjusted on

*PVT*data obtained through the vibrating tube experimental method.

**Keywords:** Volume translation; Cubic equation of state; Neural networks; Accurate; *PVT*; representation; Derived properties calculation; *PVT*; measurements; Vibrating tube densimetry

Generalized parameters of the Stryjek–Vera and Gibbons–Laughton cohesion functions for use with cubic EOS of the van der Waals type by Freddy L. Figueira; Leonor Lugo; Claudio Olivera-Fuentes (

*pp. 105-115*).

**Keywords:** Cubic equation of state; Cohesion function; Vapor pressure; Corresponding states principle; Correlation

A simplified approach to vapor–liquid equilibria calculations with the group-contribution lattice-fluid equation of state by Adam T. Jones; Samer Derawi; Ronald P. Danner; J. Larry Duda (

*pp. 116-122*).

**Keywords:** Equation of state; Polymer–solvent systems; Fugacity coefficient

Evaluation of mixing and combining rules for asymmetric Lennard–Jones chain mixtures: Effect of segment diameter, energy interaction, and chain length by Rodrigo A. Reis; Márcio L.L. Paredes; Marcelo Castier; Frederico W. Tavares (

*pp. 123-134*).

**Keywords:** Abbreviations; 1FMR; one-fluid mixing rule; CR; combining rule; EOS; equations of state; LJ; Lennard–Jones; LJC; Lennard–Jones chain; M&CR; mixing and combining rules; MD; molecular dynamics; NVT; canonical ensemble; RDF; radial distribution function at the contact point; RDFD; radial distribution function for dimmers; SEXPS; SEXP-SAFT model; SS; Soft-SAFT model; SSD; Soft-SAFT-dimer model; TPT; Thermodynamic Polymerization Theory; TPTD; Dimer Thermodynamic Polymerization Theory; vdW1F; van der Waals one-fluid approximationCombining rules; Mixing rules; Mixtures; Lennard–Jones chains; Equations of state