High-pressure densities and derived volumetric properties (excess, apparent, and partial molar volumes) of binary mixtures of {methanol (1) + [BMIM][BF4] (2)}

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Abstract

The density of seven {(0.0087, 0.0433, 0.1302, 0.2626, 0.4988, 0.7501, and 0.9102) mole fraction of [BMIM][BF4]} binary {methanol (1) + [BMIM][BF4] (2)} (1-butyl-3-methylimidazolium tetrafluoroborate) mixtures has been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from (298 to 398) K and at pressures up to 40 MPa. The total uncertainties of density, temperature, pressure, and concentration measurements was estimated to be less than 0.15 kg · m−3, 15 mK, 5 kPa, and 10−4, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The effect of temperature, pressure, and concentration on the density and derived volumetric properties such as excess, apparent, and partial molar volumes was studied. The measured densities were used to develop a Tait-type equation of state for the mixture. The structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept and the equation of state for the mixture at infinite dilution.

Introduction

Scientific and technological interest in the properties of room-temperature ionic liquids (ILs) and their mixture with other fluids is rapidly increasing [1], [2], [3], [4], while their thermodynamic and structural properties have not yet been studied systematically. The ILs and IL-containing mixtures are involved in the development of chemical products and synthetic procedures, which are environmentally friendly and have reduced health risks with the search for more efficient methods to do chemistry. Binary mixtures of ILs and other fluids have been used for electrochemical applications (solar cells) and have considerably improved the performance of the device [5], [6], [7]. The ILs-containing mixtures can also improve the thermodynamic and transport properties of working fluids as well as the efficiency of the chemical equipment (batteries, photoelectrical cells, and other electrochemical apparatus). The use of the mixtures, of ILs with other compounds (organic solvents, alcohols and water, for example) allows change and control of the properties of the mixtures to suit a given situation. The utilization of ILs and their mixtures with other fluids (organic solvents and water, for example) in industrial chemistry requires complete knowledge of their thermodynamic and transport properties, which are urgently needed for chemical process design. The volumetric properties (density, excess, apparent, and partial molar volumes) provide useful information on the structural and intermolecular interaction between the solvent and solute molecules with different sizes, shapes, and chemical nature. Introduction of an alcohol to an IL alters other thermodynamic and transport properties such as density and viscosity (see for example [8], [9]). The prediction of the changes to the properties and the ability to understand the fundamental mechanism at the molecular level are very difficult matters due to the complexity of the interactions between the complex IL ions (anions and cations) and neutral solvent molecules.

A literature survey revealed that there are only two density data sets reported by Zafarani-Moattar and Shekaari [10], [11], [12] and Iglesias et al. [13] for {methanol (1) + [BMIM][BF4] (2)} at temperatures from (293.15 to 323.15) K and at atmospheric pressure. There are no reported density data for this mixture under pressure. The volumetric properties of the mixture [BMIM][BF4] with other liquids such as water, ethanol, acetonitrile, dichloromethane, 2-butanone, N,N-dimethylformamide, and NTf2 were measured by other authors [14], [15], [16], [17]. Previously [18], we reported the densities and other derived volumetric properties for {ethanol (1) + [BMIM][BF4] (2)} over the same temperature and pressure ranges using the same apparatus. The density of mixtures of other ILs ([BMIM][OcSO4], [MMIM][CH3SO4], [BMIM][CH3SO4], [OMIM][BF4], and [HMIM][PF6]) with alcohols and n-alkanes was also measured by other authors [19], [20]. The main objective of this work is to provide new accurate experimental density data for binary {methanol (1) + [BMIM][BF4] (2)} at temperatures from (298 to 398) K and at pressures (up to 40 MPa) over a whole composition range using a vibrating-tube technique. We also reported the derived volumetric (such as excess, partial, and apparent molar volumes) and structural (direct and total correlation function integrals) properties for this mixture. The present results considerably expand the available thermodynamic database for {methanol (1) + [BMIM][BF4] (2)}.

Section snippets

Experimental

The (p, ρ, T, x2) relationship of {methanol (1) + [BMIM][BF4] (2)} was studied using a modified high pressure–high temperature Anton-Paar vibrating-tube densimeter (model DMA HTP). The physical basis and the theory of the method have been described by Retsina et al. [21] and Pádua et al. [22]. The details of the apparatus, procedures of the measurements, and uncertainty assessment have been described earlier [18]; therefore, only essential information will be given here. The vibrating tube is fixed

Results and discussion

Measurements of the density of {methanol (1) + [BMIM][BF4] (2)} as a function of temperature, pressure, and concentration were performed at seven concentrations of {(0.0087, 0.0433, 0.1302, 0.2626, 0.4988, 0.7501, and 0.9102) mole fraction of [BMIM][BF4]} for the temperatures between (298.15 and 398.15) K. The pressure ranged from (0.1 to 40) MPa. The experimental results are presented in table 1. This table also includes apparent molar volumes, derived as discussed below (see section 3.3). Some

Conclusions

Densities of seven {(0.0087, 0.0433, 0.1302, 0.2626, 0.4988, 0.7501, and 0.9102) mole fraction of [BMIM][BF4]} binary {methanol (1) + [BMIM][BF4] (2)} mixtures have been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from (298 to 398) K and at pressures up to 40 MPa. The volumetric properties (excess, apparent, and partial molar volumes) were calculated using the measured densities as a function of temperature, pressure, and concentration. The values of excess

Acknowledgements

I.M. Abdulagatov thanks the Physical and Chemical Properties Division at the National Institute of Standards and Technology for the opportunity to work as a Guest Researcher at NIST during the course of this research. Dr. J.T. Safarov also thanks the Alexander von Humboldt Foundation of Germany for the support of his research work at the Rostock University of Germany. The authors would also like to thank Dr. J.W. Magee for his interest in the work and for useful discussion.

References (89)

  • T. Hofman et al.

    J. Chem. Thermodyn.

    (2008)
  • M.T. Zafarani-Moattar et al.

    J. Chem. Thermodyn.

    (2006)
  • M.T. Zafarani-Moattar et al.

    J. Chem. Thermodyn.

    (2006)
  • R. Gomes de Azevedo et al.

    J. Chem. Thermodyn.

    (2005)
  • A. Heintz

    J. Chem. Thermodyn.

    (2005)
  • Y.A. Sanmamed et al.

    Fluid Phase Equilibr.

    (2007)
  • K.N. Marsh et al.

    Fluid Phase Equilibr.

    (2004)
  • J.H. Dymond et al.

    J. Chem. Thermodyn.

    (1988)
  • H.J. Albert et al.

    Fluid Phase Equilibr.

    (1985)
  • G. Watson et al.

    Fluid Phase Equilibr.

    (2006)
  • I.M. Abdulagatov et al.

    J. Chem. Thermodyn.

    (2006)
  • Y. Zhong et al.

    J. Chem. Thermodyn.

    (2007)
  • D.B. Mcguigan et al.

    Fluid Phase Equilibr.

    (1990)
  • J.M.H. Levelt Sengers

    J. Supercrit. Fluids

    (1991)
  • J.P. O’Connell et al.

    Fluid Phase Equilibr.

    (1999)
  • P.T. Cummings et al.

    Chem. Eng. Sci.

    (1994)
  • Z. Atik

    J. Chem. Thermodyn.

    (2006)
  • B. Orge et al.

    Fluid Phase Equilibr.

    (1997)
  • E.C. Ihmels et al.

    J. Chem. Thermodyn.

    (2005)
  • D.R. MacFarlane et al.

    Aust. J. Chem.

    (2007)
  • M. Deetlefs et al.

    Chim. Oggi Chem. Today

    (2006)
  • R.D. Rogers, K.R. Seddon (Eds.), Ionic Liquids as Green Solvents: Progress and Prospects. ACS Symposium Series, vol....
  • P. Wang et al.

    J Am. Chem. Soc.

    (2005)
  • P. Wang et al.

    Chem. Mater.

    (2004)
  • M.E. Van Valkenburg et al.

    Thermochim. Acta

    (2005)
  • G. Annat et al.

    J. Phys. Chem. B

    (2007)
  • M.T. Zafarani-Moattar et al.

    J. Chem. Eng. Data

    (2005)
  • M.A. Iglesias-Otero et al.

    J. Sol. Chem.

    (2007)
  • J. Wang et al.

    Green Chem.

    (2003)
  • Q. Zhou et al.

    J. Chem. Eng. Data

    (2006)
  • L.P.N. Rebelo et al.

    Green Chem.

    (2004)
  • J.N.C. Lopes et al.

    J. Phys. Chem.

    (2005)
  • I.M. Abdulagatov et al.

    Int. J. Thermophys.

    (2008)
  • U. Domańska et al.

    J. Sol. Chem.

    (2006)
  • A. Arce et al.

    J. Sol. Chem.

    (2006)
  • T. Retsina et al.

    Appl. Sci. Res.

    (1986)
  • A.A.H. Pádua et al.

    Int. J. Thermophys.

    (1996)
  • J. Jacquemin et al.

    Green Chem.

    (2006)
  • W. Wagner et al.

    J. Phys. Chem. Ref. Data.

    (2002)
  • I.M. Abdulagatov et al.

    J. Sol. Chem.

    (2008)
  • K.M. de Reuck et al.

    Methanol. International Thermodynamic Tables of the Fluid State-12

    (1993)
  • J.G. Huddleston et al.

    Green Chem.

    (2001)
  • K.R. Seddon et al.

    Pure Appl. Chem.

    (2000)

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