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Martins LF, Palace Carvalho AJ, Morgado P, Filipe EJ. Solubility of xenon in liquid n-alkanes and cycloalkanes by computer simulation. Towards the perfect anaesthetic. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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2
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Morgado P, Colaço B, Santos V, Jackson G, Filipe EJM. Modelling the thermodynamic properties and fluid-phase equilibria of n-perfluoroalkanes and their binary mixtures with the SAFT- γ Mie group contribution equation of state. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1722270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Pedro Morgado
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Beatriz Colaço
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Vera Santos
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London, UK
| | - George Jackson
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London, UK
| | - Eduardo J. M. Filipe
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
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3
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Morgado P, Das G, McCabe C, Filipe EJM. Vapor pressure of perfluoroalkylalkanes: the role of the dipole. J Phys Chem B 2015; 119:1623-32. [PMID: 25526174 DOI: 10.1021/jp5109448] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The vapor pressure of four liquid perfluoroalkylalkanes (CF3(CF2)n(CH2)mCH3; n = 3, m = 4,5,7; n = 5, m = 5) was measured as a function of temperature between 278 and 328 K. Molar enthalpies of vaporization were calculated from the experimental data, and the results were compared with data from the literature for the corresponding alkanes and perfluoroalkanes. The heterosegmented statistical associating fluid theory was used to interpret the results at the molecular level both with and without the explicit inclusion of the dipolar nature of the molecules. Additionally, ab initio calculations were performed for all perfluoroalkylalkanes studied to determine the dipole moment to be used in the theoretical calculations. We demonstrate that the inclusion of a dipolar term is essential for describing the vapor-liquid equilibria of perfluoroalkylalkanes. It is also shown that vapor-liquid equilibria in these compounds result from a subtle balance between dipolar interactions, which decrease the vapor pressure, and the relatively weak dispersive interactions between the hydrogenated and fluorinated segments.
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Affiliation(s)
- Pedro Morgado
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , 1049-001 Lisboa, Portugal
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4
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Domínguez H, Haslam AJ, Jackson G, Müller EA. Modelling and understanding of the vapour–liquid and liquid–liquid interfacial properties for the binary mixture of n-heptane and perfluoro-n-hexane. J Mol Liq 2013. [DOI: 10.1016/j.molliq.2012.09.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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5
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Morgado P, Bonifácio R, Martins LFG, Filipe EJM. Probing the Structure of Liquids with 129Xe NMR Spectroscopy: n-Alkanes, Cycloalkanes, and Branched Alkanes. J Phys Chem B 2013; 117:9014-24. [DOI: 10.1021/jp4060507] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pedro Morgado
- Centro de Química Estrutural,
Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal
| | - Rui Bonifácio
- Centro de Química Estrutural,
Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal
| | - Luís F. G. Martins
- Centro de Química de
Évora, Universidade de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, Portugal
| | - Eduardo J. M. Filipe
- Centro de Química Estrutural,
Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal
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6
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Ledbetter MP, Saielli G, Bagno A, Tran N, Romalis MV. Observation of scalar nuclear spin–spin coupling in van der Waals complexes. Proc Natl Acad Sci U S A 2012; 109:12393-12397. [PMCID: PMC3411965 DOI: 10.1073/pnas.1203108109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024] Open
Abstract
Scalar couplings between covalently bound nuclear spins are a ubiquitous feature in nuclear magnetic resonance (NMR) experiments, imparting valuable information to NMR spectra regarding molecular structure and conformation. Such couplings arise due to a second-order hyperfine interaction, and, in principle, the same mechanism should lead to scalar couplings between nuclear spins in unbound van der Waals complexes. Here, we report the first observation of scalar couplings between nuclei in van der Waals complexes. Our measurements are performed in a solution of hyperpolarized 129Xe and pentane, using superconducting quantum interference devices to detect NMR in 10 mG fields, and are in good agreement with calculations based on density functional theory. van der Waals forces play an important role in many physical phenomena. The techniques presented here may provide a new method for probing such interactions.
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Affiliation(s)
| | - Giacomo Saielli
- Istituto CNR per la Tecnologia delle Membrane, Sezione di Padova, Via Marzolo, 1-35131 Padova, Italy; and
| | - Alessandro Bagno
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo, 1-35131 Padova, Italy
| | - Nhan Tran
- Department of Physics, Princeton University, Princeton, NJ 08544
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7
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8
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Morgado P, Lewis JB, Laginhas CMC, Martins LFG, McCabe C, Blas FJ, Filipe EJM. Systems Involving Hydrogenated and Fluorinated Chains: Volumetric Properties of Perfluoroalkanes and Perfluoroalkylalkane Surfactants. J Phys Chem B 2011; 115:15013-23. [DOI: 10.1021/jp207567y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Pedro Morgado
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal
| | - J. Ben Lewis
- Department of Chemical and Biomolecular Engineering and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Carlos M. C. Laginhas
- Centro de Química de Évora, Universidade de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, Portugal
| | - Luís F. G. Martins
- Centro de Química de Évora, Universidade de Évora, Rua Romão Ramalho, 59, 7000-671 Évora, Portugal
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Felipe J. Blas
- Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva, Spain
| | - Eduardo J. M. Filipe
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal
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9
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dos Ramos MC, Blas FJ. Theoretical investigation of the phase behaviour of mixtures of a novel family of perfluoroalkyl–polyoxyethylene ether diblock surfactants in aqueous solutions of carbon dioxide. J Supercrit Fluids 2010. [DOI: 10.1016/j.supflu.2010.10.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Interfacial tension measurements and modelling of (carbon dioxide+n-alkane) and (carbon dioxide+water) binary mixtures at elevated pressures and temperatures. J Supercrit Fluids 2010. [DOI: 10.1016/j.supflu.2010.09.028] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Bonifácio RPMF, Martins LFG, McCabe C, Filipe EJM. On the Behavior of Solutions of Xenon in Liquid n-Alkanes: Solubility of Xenon in n-Pentane and n-Hexane. J Phys Chem B 2010; 114:15897-904. [DOI: 10.1021/jp105713m] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Rui P. M. F. Bonifácio
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal, Centro de Química de Évora, Universidade de Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal, and Department of Chemical and Biomolecular Engineering, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235-1604, United States
| | - Luís F. G. Martins
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal, Centro de Química de Évora, Universidade de Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal, and Department of Chemical and Biomolecular Engineering, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235-1604, United States
| | - Clare McCabe
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal, Centro de Química de Évora, Universidade de Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal, and Department of Chemical and Biomolecular Engineering, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235-1604, United States
| | - Eduardo J. M. Filipe
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal, Centro de Química de Évora, Universidade de Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal, and Department of Chemical and Biomolecular Engineering, and Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235-1604, United States
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12
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Llovell F, Galindo A, Blas FJ, Jackson G. Classical density functional theory for the prediction of the surface tension and interfacial properties of fluids mixtures of chain molecules based on the statistical associating fluid theory for potentials of variable range. J Chem Phys 2010; 133:024704. [DOI: 10.1063/1.3449143] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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dos Ramos MC, Blas FJ. Theoretical investigation of the phase behaviour of model ternary mixtures containingn-alkanes, perfluoro-n-alkanes, and perfluoroalkylalkane diblock surfactants. Mol Phys 2010. [DOI: 10.1080/00268971003692000] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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15
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Podgorsek A, Stavber S, Zupan M, Iskra J, Padua AAH, Gomes MFC. Solvation of Halogens in Fluorous Phases. Experimental and Simulation Data for F2, Cl2, and Br2 in Several Fluorinated Liquids. J Phys Chem B 2008; 112:6653-64. [DOI: 10.1021/jp7121104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- A. Podgorsek
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, “Jozef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia, and Laboratoire de Thermodynamique des Solutions et des Polymères, Université Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 avenue des Landais, 63177 Aubière, France
| | - S. Stavber
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, “Jozef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia, and Laboratoire de Thermodynamique des Solutions et des Polymères, Université Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 avenue des Landais, 63177 Aubière, France
| | - M. Zupan
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, “Jozef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia, and Laboratoire de Thermodynamique des Solutions et des Polymères, Université Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 avenue des Landais, 63177 Aubière, France
| | - J. Iskra
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, “Jozef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia, and Laboratoire de Thermodynamique des Solutions et des Polymères, Université Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 avenue des Landais, 63177 Aubière, France
| | - A. A. H. Padua
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, “Jozef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia, and Laboratoire de Thermodynamique des Solutions et des Polymères, Université Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 avenue des Landais, 63177 Aubière, France
| | - M. F. Costa Gomes
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, “Jozef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia, and Laboratoire de Thermodynamique des Solutions et des Polymères, Université Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 avenue des Landais, 63177 Aubière, France
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16
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Zhao H, Ding Y, McCabe C. Phase behavior of dipolar associating fluids from the SAFT-VR+D equation of state. J Chem Phys 2007; 127:084514. [PMID: 17764276 DOI: 10.1063/1.2756038] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The statistical associating fluid theory for potentials of variable range plus dipole (SAFT-VR+D) is extended to study associating dipolar fluids. In the SAFT-VR+D approach dipolar interactions are taken into account through the use of the generalized mean spherical approximation to describe a reference fluid of dipolar square-well segments. This enables the effect of the dipolar interactions on the thermodynamics and structure of fluids to be explicitly described. Predictions for the thermodynamic properties and phase behavior of dipolar associating square-well monomers with one, two, and four association sites are considered and compared with new isothermal-isobaric and Gibbs ensemble Monte Carlo simulation data. The results show that the SAFT-VR+D equation provides a good description of the phase behavior of dipolar associating fluids. Additionally we have applied the new theoretical approach to study the vapor pressure and saturated liquid density of water.
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Affiliation(s)
- Honggang Zhao
- Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
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17
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Zhao H, dos Ramos MC, McCabe C. Development of an equation of state for electrolyte solutions by combining the statistical associating fluid theory and the mean spherical approximation for the nonprimitive model. J Chem Phys 2007; 126:244503. [PMID: 17614560 DOI: 10.1063/1.2733673] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A statistical associating fluid theory to model electrolyte fluids that explicitly accounts for solvent molecules by modeling water as a dipolar square-well associating fluid is presented. Specifically the statistical associating fluid theory for potentials of variable range (SAFT-VR) is combined with integral equation theory and the generalized mean spherical approximation using the nonprimitive model to describe the long-range ion-ion, ion-dipole, and dipole-dipole interactions. Isothermal-isobaric ensemble Monte Carlo simulations have been performed in order to test the new theoretical approach. In particular, simulations are performed for different ion concentrations and different ratios of the cation, anion, and solvent segment diameters. Predictions for the thermodynamic properties from the new equation of state are compared with the computer simulation data. Additionally, results from a combination of the SAFT-VR approach with Debye-Huckel theory and the primitive model are also presented and compared to those obtained with the nonprimitive model to illustrate the advantages of the new statistical associating fluid theory for potentials of variable range plus dipole and electrolytes (SAFT-VR+DE) approach. The results show that the proposed equation of state provides a good description of the PVT properties of electrolyte fluids with different sizes of ions and solvent.
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Affiliation(s)
- Honggang Zhao
- Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
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18
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Carolina Dos Ramos M, Blas FJ. Theory of phase equilibria for model mixtures of n-alkanes, perfluoroalkanes and perfluoroalkylalkane diblock surfactants. Mol Phys 2007. [DOI: 10.1080/00268970701297575] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Dias LMB, Filipe EJM, McCabe C, Cordeiro T, Calado JCG. Liquid Mixtures of Xenon with Fluorinated Species: Xenon + Sulfur Hexafluoride. J Phys Chem B 2007; 111:5284-9. [PMID: 17447805 DOI: 10.1021/jp065222j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The vapor-liquid equilibrium of binary mixtures of xenon + SF6 has been measured at nine temperatures from 235.34 to 295.79 K and pressures up to 6.5 MPa. The mixture critical line is found to be continuous between the critical points of the pure components, and hence, the system can be classified as type I phase behavior in the scheme of van Konynenburg and Scott. The excess Gibbs free energies have been calculated, and the experimental results have been interpreted using the statistical associating fluid theory for potentials of variable range (SAFT-VR). Additionally, the SAFT-VR equation has been used to model other systems involving SF6 and alkanes, illustrating the predictability of the approach and further demonstrating the transferability of parameters between binary mixtures involving alkanes and xenon.
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Affiliation(s)
- Lino M B Dias
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
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20
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Morgado P, Zhao H, Blas FJ, McCabe C, Rebelo LPN, Filipe EJM. Liquid Phase Behavior of Perfluoroalkylalkane Surfactants. J Phys Chem B 2007; 111:2856-63. [PMID: 17388407 DOI: 10.1021/jp063136d] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We have performed a combined experimental and theoretical study of the thermodynamic properties of semifluorinated alkanes. In particular, the liquid density of perfluorohexylhexane (F6H6) and perfluorohexyloctane (F6H8) has been measured as a function of temperature from 273.15 to 353.15 K and at four temperatures as a function of pressure up to 600 bar. The results were interpreted using the SAFT-VR equation of state. The perfluoroalkylalkanes were modeled as heterosegmented diblock chains using parameters for the alkyl and perfluoroalkyl segments developed in earlier work. Through this simple approach, we are able to predict the thermodynamic behavior of the perfluoroalkylalkanes studied without fitting to any experimental data for the systems being studied.
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Affiliation(s)
- Pedro Morgado
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
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21
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Sun L, Zhao H, McCabe C. Predicting the phase equilibria of petroleum fluids with the SAFT-VR approach. AIChE J 2007. [DOI: 10.1002/aic.11110] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Zhao H, Morgado P, Gil-Villegas A, McCabe C. Predicting the Phase Behavior of Nitrogen + n-Alkanes for Enhanced Oil Recovery from the SAFT-VR Approach: Examining the Effect of the Quadrupole Moment. J Phys Chem B 2006; 110:24083-92. [PMID: 17125380 DOI: 10.1021/jp063444b] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The phase behavior of nitrogen + n-alkanes is studied within the framework of the statistical associating fluid theory for potentials of variable range (SAFT-VR). The effect of the quadrupole moment of nitrogen on the phase behavior is considered through an extension of the SAFT-VR equation that includes an additional contribution to the Helmholtz free energy due to quadrupolar interactions. A significant improvement in the description of the phase diagram of the binary mixtures of nitrogen with different n-alkanes is obtained with the new approach when compared to predictions from the original SAFT-VR EOS (i.e., without the quadrupolar term). The experimental value for the quadrupole moment of nitrogen is used in the new equation; thus, no additional parameters are employed. Given the nonideal nature of the binary mixtures, a binary interaction parameter is needed to describe the full-phase diagram and high-pressure critical lines of these systems; however, this can be fitted to a single system and successfully used to predict the phase behavior of other binary mixtures without additional fitting. Furthermore, only a single, transferable, cross-energy parameter is required when the quadrupolar term is considered, whereas a cross-range parameter is also needed with the original SAFT-VR approach. The inclusion of the quadrupolar term in the equation of state therefore reduces the need to use effective parameters by explicitly including at the molecular level interactions due to the quadrupole moment.
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Affiliation(s)
- Honggang Zhao
- Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235-1604, USA
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23
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Zhao H, McCabe C. Phase behavior of dipolar fluids from a modified statistical associating fluid theory for potentials of variable range. J Chem Phys 2006; 125:104504. [PMID: 16999538 DOI: 10.1063/1.2337624] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A statistical associating fluid theory for potentials of variable range to model dipolar fluids is presented. The new theory, termed the SAFT-VR+D equation (the statistical associating fluid theory for potentials of variable range plus dipole), explicitly accounts for dipolar interactions and their effect on the structure of the fluid. This is achieved through the use of the generalized mean spherical approximation (GMSA) to describe a reference fluid of dipolar square-well segments. Isothermal-isobaric and Gibbs ensemble Monte Carlo simulations have been performed in order to test the new theoretical approach. Predictions for the thermodynamic properties and phase behavior of dipolar square-well monomer and chain fluids, in which one or more segments are dipolar, are considered and compared with new computer simulation data. The results show that the equation of state in general provides a good description of the phase behavior of dipolar monomer and chain fluids. Some deviations are seen between the simulation data and theoretical predictions for monomer fluids with large dipole moments and for molecules composed of segments with dipoles in different orientations. This is addressed through the replacement of the GMSA by the linearized exponential approximation.
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Affiliation(s)
- Honggang Zhao
- Department of Chemical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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24
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Costa Gomes MF, Deschamps J, Pádua AAH. Interactions of Nitrous Oxide with Fluorinated Liquids. J Phys Chem B 2006; 110:18566-72. [PMID: 16970485 DOI: 10.1021/jp062995z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The interactions of nitrous oxide with fluorinated liquids are investigated by reporting original experimental results on gas solubility and interpreting them using molecular simulation. Nitrous oxide is highly soluble in the three fluorinated liquids studied-perfluorooctane, 1-bromoperfluorooctane (perfluorooctylbromide), and perfluorohexylethane-with mole fraction solubilities on the order of 0.03 under ambient conditions. An intermolecular potential model was developed for nitrous oxide, with a functional form of the Lennard-Jones plus point charges type, adjusted to the experimental multipole moments and to vapor-liquid equilibrium properties. The solubility of nitrous oxide in perfluorocarbon liquids was calculated by molecular simulation methods, and a dissimilar interaction parameter of 0.92 in the Lennard-Jones well-depths between solute and solvent had to be introduced to reach agreement with the experimental results, similar to what is found for hydrocarbon-fluorocarbon interactions. The structure of the solutions was studied by analysis of solute-solvent radial distribution functions, showing that, although electrostatic interactions are not predominant, a small orientational effect is still present between the dipole of nitrous oxide and those of the substituted fluorinated liquids.
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Affiliation(s)
- Margardia F Costa Gomes
- Laboratoire de Themodynamique des Solutions et des Polyméres, Université Blaise Pascal Clermont-Ferrand/CNRs, France.
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25
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Peng Y, Zhao H, Mccabe C. On the thermodynamics of diblock chain fluids from simulation and heteronuclear statistical associating fluid theory for potentials of variable range. Mol Phys 2006. [DOI: 10.1080/00268970500475901] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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26
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Sun L, Zhao H, Kiselev SB, McCabe C. Predicting Mixture Phase Equilibria and Critical Behavior Using the SAFT-VRX Approach. J Phys Chem B 2005; 109:9047-58. [PMID: 16852077 DOI: 10.1021/jp044413o] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The SAFT-VRX equation of state combines the SAFT-VR equation with a crossover function that smoothly transforms the classical equation into a nonanalytical form close to the critical point. By a combinination of the accuracy of the SAFT-VR approach away from the critical region with the asymptotic scaling behavior seen at the critical point of real fluids, the SAFT-VRX equation can accurately describe the global fluid phase diagram. In previous work, we demonstrated that the SAFT-VRX equation very accurately describes the pvT and phase behavior of both nonassociating and associating pure fluids, with a minimum of fitting to experimental data. Here, we present a generalized SAFT-VRX equation of state for binary mixtures that is found to accurately predict the vapor-liquid equilibrium and pvT behavior of the systems studied. In particular, we examine binary mixtures of n-alkanes and carbon dioxide + n-alkanes. The SAFT-VRX equation accurately describes not only the gas-liquid critical locus for these systems but also the vapor-liquid equilibrium phase diagrams and thermal properties in single-phase regions.
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Affiliation(s)
- Lixin Sun
- Department of Chemical Engineering, Vanderbilt University, Nashville, Tennessee 37235-1604, USA
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Gloor GJ, Jackson G, Blas FJ, Del Río EM, de Miguel E. An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range. J Chem Phys 2004; 121:12740-59. [PMID: 15606300 DOI: 10.1063/1.1807833] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A Helmholtz free energy density functional is developed to describe the vapor-liquid interface of associating chain molecules. The functional is based on the statistical associating fluid theory with attractive potentials of variable range (SAFT-VR) for the homogenous fluid [A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, and A. N. Burgess, J. Chem. Phys. 106, 4168 (1997)]. A standard perturbative density functional theory (DFT) is constructed by partitioning the free energy density into a reference term (which incorporates all of the short-range interactions, and is treated locally) and an attractive perturbation (which incorporates the long-range dispersion interactions). In our previous work [F. J. Blas, E. Martin del Rio, E. de Miguel, and G. Jackson, Mol. Phys. 99, 1851 (2001); G. J. Gloor, F. J. Blas, E. Martin del Rio, E. de Miguel, and G. Jackson, Fluid Phase Equil. 194, 521 (2002)] we used a mean-field version of the theory (SAFT-HS) in which the pair correlations were neglected in the attractive term. This provides only a qualitative description of the vapor-liquid interface, due to the inadequate mean-field treatment of the vapor-liquid equilibria. Two different approaches are used to include the correlations in the attractive term: in the first, the free energy of the homogeneous fluid is partitioned such that the effect of correlations are incorporated in the local reference term; in the second, a density averaged correlation function is incorporated into the perturbative term in a similar way to that proposed by Toxvaerd [S. Toxvaerd, J. Chem. Phys. 64, 2863 (1976)]. The latter is found to provide the most accurate description of the vapor-liquid surface tension on comparison with new simulation data for a square-well fluid of variable range. The SAFT-VR DFT is used to examine the effect of molecular chain length and association on the surface tension. Different association schemes (dimerization, straight and branched chain formation, and network structures) are examined separately. The surface tension of the associating fluid is found to be bounded between the nonassociating and fully associated limits (both of which correspond to equivalent nonassociating systems). The temperature dependence of the surface tension is found to depend strongly on the balance between the strength and range of the association, and on the particular association scheme. In the case of a system with a strong but very localized association interaction, the surface tension exhibits the characteristic "s shaped" behavior with temperature observed in fluids such as water and alkanols. The various types of curves observed in real substances can be reproduced by the theory. It is very gratifying that a DFT based on SAFT-VR free energy can provide an accurate quantitative description of the surface tension of both the model and experimental systems.
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Affiliation(s)
- Guy J Gloor
- Department of Chemical Engineering and Chemical Technology, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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Dias AMA, Pàmies JC, Coutinho JAP, Marrucho IM, Vega LF. SAFT Modeling of the Solubility of Gases in Perfluoroalkanes. J Phys Chem B 2003. [DOI: 10.1021/jp036225o] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ana M. A. Dias
- CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal, Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans, 26, 43007 Tarragona, Spain, and Institut de Ciència de Materials de Barcelona (ICMAB−CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona, Spain
| | - Josep C. Pàmies
- CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal, Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans, 26, 43007 Tarragona, Spain, and Institut de Ciència de Materials de Barcelona (ICMAB−CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona, Spain
| | - João A. P. Coutinho
- CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal, Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans, 26, 43007 Tarragona, Spain, and Institut de Ciència de Materials de Barcelona (ICMAB−CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona, Spain
| | - Isabel M. Marrucho
- CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal, Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans, 26, 43007 Tarragona, Spain, and Institut de Ciència de Materials de Barcelona (ICMAB−CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona, Spain
| | - Lourdes F. Vega
- CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal, Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans, 26, 43007 Tarragona, Spain, and Institut de Ciència de Materials de Barcelona (ICMAB−CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona, Spain
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Song W, Rossky PJ, Maroncelli M. Modeling alkane+perfluoroalkane interactions using all-atom potentials: Failure of the usual combining rules. J Chem Phys 2003. [DOI: 10.1063/1.1610435] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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