Elsevier

Fluid Phase Equilibria

Volume 472, 25 September 2018, Pages 9-21
Fluid Phase Equilibria

Molecular dynamic simulation, molecular interactions and structural properties of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide + 1-butanol/1-propanol mixtures at (298.15–323.15) K and 0.1 M Pa

https://doi.org/10.1016/j.fluid.2018.04.025Get rights and content

Highlights

  • ρ, u and η have been measured for pure and binary mixtures, IL + 1-butanol/1-propanol.

  • The VE, Κs,mE and Δη of binary mixtures have been correlated with Redlich-Kister equation.

  • The properties have been discussed in terms of ion-ion, dipole-dipole andmion-dipole interactions.

  • Experimental ρ and VE has been investigated by MD Simulation.

  • The PFP theory has been used to correlate the VE values for the studied binary systems.

Abstract

The excess molar volumes (VE), excess molar isentropic compressibilities (Κs,mE) and viscosity deviations (Δη) have been evaluated using the experimental densities, ρ, speeds of sound, u and viscosities, η data of pure ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, ([BMIM][NTF2]), 1-butanol, 1-propanol and of their binary mixtures over the entire mole fraction range of ionic liquid at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and at 0.1 MPa pressure. The VE, Κs,mE and Δη values have been fitted to Redlich-Kister polynomial equation. The experimental and computed parameters have been discussed in terms of ion-ion, ion-dipole, dipole-dipole and hydrogen bonding interactions. The ρ and VE values have also been predicted using molecular dynamics (MD) simulations, in order to correlate the thermodynamic properties to the microscopic structure of the mixtures analyzing the radial and spatial distribution functions. The Prigogine-Flory-Patterson (PFP) theory has been applied to correlate the excess molar volumes.

Introduction

Ionic liquids (ILs) are a modern class of low temperature (typically <100 °C) molten salts, comprised of distinct anions (may be organic or inorganic) and cations, which is normally a bulk organic structure with low symmetry, so they are unable to stabilize the solid lattice at ambient temperature [1]. ILs became one of the expeditiously growing area in green chemistry because of their noticeable, amazing and unique physical and chemical properties such as negligible vapour pressure, large liquidous range, thermal and electrochemical stability, high ionic conductivity, high solvating capacity, recyclable, non-flammability and good solubility for polar and non polar organic and inorganic substances [2]. From few decades, room temperature ionic liquids (RTILs) are attracting adequate attention because of their fascinating properties and large number of applications, such as entrainer for liquid-liquid extraction, extractive distillation, solvents for catalytic reaction, chemical synthesis, solar cell, heat transfer fluids and chemical sensors [3,4]. ILs have also proved to be excellent solvents for the immobilization and stabilization of metal nanoparticles, hereby providing a wonderful media for quasi-homogeneous catalysis [5], and also allow the use as electrolytes for different technologies e.g., in lithium secondary batteries, photoelectrical and fuel cells, electric double-layer capacitors, and other electrochemical devices. Ionic liquids are environmental friendly because they can be used in many extraction and cyclic processes without losses, in contrast with the volatile organic compounds [6]. The knowledge of physical properties of ionic liquids and their mixtures are necessary to advance the applications and to develop theoretical models capable to explain the physical and chemical behaviour of ionic liquids by their measurements and interpretations. Methodical analysis of thermodynamics and thermophysical properties of ionic liquids mixtures which can be determined experimentally and correlate it computationally by MD simulation are scarce. Recently, many efforts have been made to determine the thermophysical properties of ILs and their mixtures experimentally or by theoretical/computational methods [7]. The thermophysical properties, such as densities, speeds of sound and viscosities of binary mixtures, i. e, ionic liquid + organic or inorganic solvents are of great interest from both the practical and theoretical points of view [8]. The excess molar volume helps the study of structure-property relation [1] while, for the construction of different equipment related to liquid flow, viscosity can be required [9]. Therefore, to understand the properties and applications as well as to design novel processes involving ionic liquids in the industry [10], the methodical investigation on the molecular interactions and structural effects of RTILs with organic solvents is required.

1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, ([BMIM][NTF2]) is one of the air, and thermally stable hydrophobic ionic liquids [11], 1-butanol (C4H10O) is a higher member of straight chain alcohol and is strongly bonded by hydrogen bonds. Hydrogen bonds are amenable for striking behaviour and it is found to be highly associative [12]. Alcohol molecules possess the characteristic of self association and associate strongly in solution through intermolecular hydrogen bonding of their hydroxyl group and dipole-dipole interactions [[13], [14], [15]]. Furthermore, alcohols are protean solvents used in pharmaceutical industry, separation of saturated and unsaturated hydrocarbons as solvents/extracting agent and in waste water treatment [16,17].

A number of authors [23,9,[18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32]] have studied the thermophysical properties of pure [BMIM]-[NTF2] and its binary mixtures with organic solvents at different temperatures and at atmospheric and also different range of pressures.

MD simulations give access to the microscopic structure of the systems and have been employed extensively to study bulk properties of pure ILs and their mixtures [[33], [34], [35], [36], [37], [38], [39]]. MD simulations also allow direct access to one of the most interesting properties of ILs, its nanostructuration [40,41]. This nanostructuration takes a very important role in the solvation of different molecules in the IL. This is called the nanostructure solvation paradigm. In this solvation paradigm, the IL is divided in two regions, one apolar and another polar. Alcohols are placed in a very particular position in this paradigm. Being amphiphilic molecules, they are placed in the interface between both regions. This model has been already used to explain successfully experimental and simulated results for the solvation of different alcohols in protic ionic liquids [42,43].

The aim of this work is the experimental determination of thermodynamic properties of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with 1-butanol and 1-propanol as these studies are expected to provide information about molecular interactions between the various components of IL and organic solvents and the studies of excess properties help to better understand the structure property relation of IL with organic solvents.

In this work, the densities, ρ, speeds of sound, u and viscosities, η of pure [BMIM][NTF2], 1-butanol, 1-propanol and of their binary mixtures [BMIM][NTF2] + 1-butanol/1-propanol have been experimentally measured covering the entire mole fraction range of IL, at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and at pressure 0.1 MPa. The excess molar volumes, VE, excess molar isentropic compressibilities, Κs,mE, viscosity deviations, Δη, Gibbs free energy of activation, ΔG* and excess Gibbs free energy of activation, ΔG*E of binary mixture [BMIM][NTF2] + 1-butanol/1-propanol have been calculated using experimental ρ, u and η values of pure and binary components. These quantities have been used to interpret the solute-solvent interactions occurring between ionic liquid and organic solvents. The VE, Κs,mE and Δη values have been fitted to Redlich-Kister equation for both binary mixtures, [BMIM][NTF2] + 1-butanol and [BMIM][NTF2] + 1-propanol. The Prigogine-Flory-Patterson (PFP) theory [26,44] has also been applied to correlate the excess molar volumes of binary mixtures [BMIM][NTF2] + 1-butanol and [BMIM][NTF2] +1-propanol. The MD Simulation studies discussed in terms of radial and spatial distribution functions.

Section snippets

Materials

The details of ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTF2]), 1-butanol and 1-propanol used in this work is given in Table 1. The 3D structure of [BMIM][NTF2] is shown in Fig. 1.

Apparatus and procedure

Water content of the pure [BMIM][NTF2] was measured with a Karl Fischer coulometric titrator (C20, Metller Toledo), and was found to be 93.2 ppm. The binary mixtures [BMIM][NTF2](1) + 1-butanol(2) and [BMIM][NTF2](1) + 1-propanol(2) of different mole fractions were prepared

Density, speed of sound and dynamic viscosity

The measured ρ, u and η values of pure [BMIM][NTF2], 1-butanol and 1-propanol are compared with the available literature [2,3,[18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32],44,[53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66]] data and the comparison is reported in the supplementary material in Table S1. We have found a little variation between measured and literature values of supplementary material. The percent

Prigogine-Flory-Patterson (PFP) theory

The Prigogine-Flory-Patterson(PFP) statistical theory [26,44] has been used to correlate the excess molar volumes of the binary mixtures [BMIM][NTF2] + 1-butanol and [BMIM][NTF2] + 1-propanol at temperatures between 298.15 and 323.15 K. On the basis of this theory, the expression for excess molar volume is separated into three contributions as (i) an interaction contribution, V(int)E, which is proportional to the only interaction parameter, χ21, (ii) a free volume term, V(fv)E, and (iii) an

Conclusions

The VE values for both studied systems [BMIM][NTF2] + 1-butanol/1-propanol were found to be negative at low IL concentrations and at all temperatures. Indeed for molar fractions < 0.25 for [BMIM][NTF2] + 1-butanol and x1 < 0.45 for [BMIM][NTF2] + 1-propanol systems, VE values are negative at all temperatures. Negative values of VE are associated to attractive interactions in binary mixtures than those of the pure components, whereas, positive values of VE suggest that the weak attractive

Acknowledgements

The authors are thankful to the Chairman, Department of Chemistry, A.M.U., Aligarh for providing the necessary facility for the compilation of this work. Financial support from the UGC (M.R.P) [F. No. 41-240/2012 (SR)] scheme is gratefully acknowledged. The financial support of the Spanish Ministry of Economy and Competitiveness (Projects MAT2014-57943-C3-1-P, MAT2014-57943-C3-3-P, MAT2017-89239-C2-1-P and MAT2017-89239-C2-2-P) is gratefully acknowledged. Moreover, this work was funded by the

References (69)

  • B. Mokhtarani et al.

    Density and viscosity of 1-butyl-3-methylimidazolium nitrate with ethanol, 1-propanol, or 1-butanol at several temperatures

    J. Chem. Thermodyn.

    (2009)
  • I. Mozo et al.

    Thermodynamics of mixtures containing alkoxyethanols, part xxv. densities, excess molar volumes and speeds of sound at 293.15, 298.15 and 303.15 k, and isothermal compressibilities at 298.15 k for 2-alkoxyethanol + 1-butanol systems

    J. Mol. Liq.

    (2008)
  • A. Pal et al.

    Density and speed of sound for binary mixtures of 1,4-dioxane with propanol and butanol isomers at different temperatures

    J. Mol. Liq.

    (2013)
  • B. Gonzalez et al.

    Viscosity, density, and speed of sound of methylcyclopentane with primary and secondary alcohols at T = (293.15, 298.15, and 303.15) K

    J. Chem. Thermodyn.

    (2006)
  • S.L. Outcalt et al.

    Density and speed of sound measurements of 1- and 2-butanol

    J. Mol. Liq.

    (2010)
  • E.J. Gonzalez et al.

    Osmotic and apparent molar properties of binary mixtures alcohol + 1-butyl-3-methylimidazolium trifluoromethane-sulfonate ionic liquid

    J. Chem. Thermodyn.

    (2013)
  • M. Moosavi et al.

    Investigation on some thermophysical properties of poly(ethylene glycol)binary mixtures at different temperatures

    J. Chem. Thermodyn.

    (2013)
  • O. Ciocirlan et al.

    Densities and viscosities for binary mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid with molecular solvents

    J. Chem. Eng. Data

    (2011)
  • A. Fernandez et al.

    Thermophysical properties of 1-ethyl-3-methylimidazolium ethylsulfate and 1-butyl-3-methylimidazolium methylsulfate ionic liquids

    J. Chem. Eng. Data

    (2007)
  • H. Yao et al.

    Densities and viscosities of the binary mixtures of 1-ethyl- 3-methylimidazolium bis(trifluoromethylsulfonyl)imide with n-methyl-2-pyrrolidone or ethanol at T = (293.15 to 323.15) K

    J. Chem. Eng. Data

    (2012)
  • R.L. Gardas et al.

    High-pressure densities and derived thermodynamic properties of imidazolium-based ionic liquids

    J. Chem. Eng. Data

    (2007)
  • R. Salinas et al.

    Density, speed of sound, viscosity and excess properties of binary mixtures formed by ethanol and bis(trifluorosulfonyl)imide

    J. Chem. Eng. Data

    (2015)
  • M.L. Ge et al.

    Densities and viscosities of 1-butyl- 3-methylimidazolium trifluoromethanesulfonate + H2O binary mixtures at T = (303.15 to 343.15) K

    J. Chem. Eng. Data

    (2008)
  • A.P. Maharolkar et al.

    Densities, viscosities and refractive indices of n- butanol + allyl chloride mixture at 298 K

    Int. J. Chem.

    (2010)
  • S.S. Sastry et al.

    Study of molecular interactions in the mixtures of some primary alcohols with equimolar mixture of 1-propanol and alkylbenzoates at T = 303.15 K

    J. Chem. Thermodyn.

    (2014)
  • M.C. Sekhar et al.

    Thermodynamic and theoretical study on hydrogen bonded binary mixtures of isomeric butanols with o-toluidine at T = (303.15 to 318.15) K

    J. Mol. Liq.

    (2015)
  • S.S. Sastryan et al.

    Excess parameters for binary mixtures of ethyl benzoate with1-propanol, 1-butanol and 1-pentanol at T = 303, 308, 313, 318 and 323 K

    Physica B

    (2013)
  • C. Valles et al.

    Excess enthalpy, density, speed of sound, and viscosity for 2-methyltetrahydrofuran + 1-butanol at (283.15, 298.15, and, 313.15) K

    J. Chem. Eng. Data

    (2006)
  • A. Wandschneider et al.

    Surface tension and density of pure ionic liquids and some binary mixtures with 1-propanol and 1-butanol

    J. Chem. Eng. Data

    (2008)
  • R. Salinas et al.

    Density, viscosity and speed of sound bis(trifluoromethylsulfonyl)imide-based ionic liquids + 1-propanol mixtures

    J. Chem. Eng. Data

    (2016)
  • K.R. Harris et al.

    Temperature and pressure dependence of the viscosity of the ionic liquids 1-hexyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

    J. Chem. Eng. Data

    (2007)
  • J. Troncoso et al.

    L.P.N. Rebelo Thermodynamic properties of imidazolium-based ionic liquids: Densities, heat capacities, and enthalpies of fusion of [bmim][PF6] and [bmim][NTf2]

    J. Chem. Eng. Data

    (2006)
  • M. Krummen et al.

    Measurement of activity coefficients at infinite dilution in ionic liquids using the dilutor technique

    J. Chem. Eng. Data

    (2002)
  • S. Garcia et al.

    Liquid-liquid extraction of toluene from heptane using 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids

    J. Chem. Eng. Data

    (2011)
  • Cited by (17)

    • Thermodynamic study of binary mixtures of 2-propanol with ionic liquids, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexylammonium bis(trifluoromethylsulfonyl)imide

      2022, Journal of Chemical Thermodynamics
      Citation Excerpt :

      Prigogine-Flory-Patterson theory has been originally used in interpreting the values of the excess molar volumes of binary systems formed by polar compounds which do not form strong electrostatic or hydrogen bond interactions. However, despite the ionic character of the IL systems, the PFP theory has been successfully applied to predict and model the excess molar volumes of many mixtures containing ionic liquids [64-68]. As stated by PFP theory, the excess molar volume contains three contributions: an interactional contribution, a free volume contribution and a pressure contribution.

    • Density, viscosity and excess properties of binary mixtures of ethylene glycol and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

      2022, Journal of Molecular Liquids
      Citation Excerpt :

      Fatima et al. examined viscosities, speeds of sound and densities of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-butanol/1-propanol binary mixtures prepared with a wide mole fraction range at temperatures ranging from 298.15 K to 323.15 K. They also investigated the molecular interactions of the mixtures [27]. Alcalde et al. investigated intermolecular forces in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide and ethanol mixtures using both experimental and theoretical methods [28].

    • Effect of dilution of nonpolar solvents (CCl<inf>4</inf> and C<inf>6</inf>H<inf>6</inf>) on densities and excess molar volumes of methanol + 1-butanol mixtures over the temperature range 293.15–308.15 K

      2021, Journal of Molecular Liquids
      Citation Excerpt :

      The data have been presented in the tabulated and/or plotted forms. Following Table 2 depicts some basic reported properties of the solvents employed [26–30]. Density is one of the basic properties of any liquid that may vary with temperature.

    • Investigation on thermophysical properties of binary systems of [C<inf>4</inf>mim][NTf<inf>2</inf>] with cyclic ethers: Application of PFP and ERAS theories

      2020, Journal of Molecular Liquids
      Citation Excerpt :

      This behavior was supported by the accommodation of small molecules in to the free space provided by IL and strong ion-dipole interactions between components of the mixtures. Similarly, the positive excess molar properties were reported for binary systems with methanol or dimethyl sulfoxide [40], 2,2,2-trifluoroethanol [41], 2-methoxyethanol [42], 1-butanol or 1- propanol [43,44] due to formation of H-bonding between IL and studied solvents. Table 1 represents the CAS No., make, method of purification and improved purity of components used in present investigation. [

    • Experimental and MD simulation investigation on thermophysical properties of binary/ternary mixtures of 1-butyl-3-methylimidazolium trifluoromethanesulfonate with molecular solvents

      2020, Journal of Molecular Liquids
      Citation Excerpt :

      Some semi-empirical models [32–36] have also been applied for the correlation of dynamic viscosity data and to determine some interaction parameters of the studied binary systems in terms of pure components data. The Prigogine-Flory-Patterson (PFP) theory [9,10,37] has also been used to correlate the excess molar volumes VE for all the studied binary mixtures. In addition to this, the effect of DMSO/EG on [BMIM][CF3SO3] or DMSO on EG is further explored with the aid of computational simulation studies (MD simulations).

    View all citing articles on Scopus
    View full text