Thermophysical properties of 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide with 2-ethoxyethanol from T = (298.15 to 323.15) K at atmospheric pressure G. Prasad a,f , K. Muralidhar Reddy b , R. Padamasuvarna c , T. Madhu Mohan d, ⁎, T. Vijaya Krishna d, ⁎, V. Ramesh Kumar e a Research Scholar, Departmentof Physics, JNTUA-College of Engineering, Ananthapuramu, Andhra Pradesh, India b Department of EIE, R.G.M. College of Engineering & Technology, Nandyal, Andhra Pradesh, India c Department of Physics, JNTUA-College of Engineering, Ananthapuramu, Andhra Pradesh, India d Department of Physics, Vasireddy Venkatadri Institute of Technology, Nambur, Andhra Pradesh, India e Department of Physics, Govt. Degree College, Pathikonda, Andhra Pradesh, India f Department of Physics, SASI Institute ofTechnology & Engineering, Tadepalligudem, Andhra Pradesh, India abstract article info Article history: Received 25 September 2017 Received in revised form 27 November 2017 Accepted 5 December 2017 Available online 08 December 2017 Density (ρ) and speed of sound (u) data is determined for various binary compositions of 1-butyl-3- methylimidazolium bis (trifluoromethylsulfonyl) imide ([Bmim][NTf 2 ]) and 2-ethoxyethanol (2EE) at different temperatures. The experimental data of density and speed of sound is used to calculate the values of excess molar volume, excess isentropic compressibility, excess intermolecular free length and excess speed of sound. The variations in these parameters are analysed to understand the nature of molecular interactions between the chemical species. Redlich-Kister equation is used to estimate the deviations between the calculated and ex- perimental excess values. The values of partial molar volume, excess partial molar volume and excess partial molar volume at infinite dilution have been calculated. The trends of variation of these properties have been interpreted in light of the solute-solvent interactions occurring in the system. Further, the experimental FT-IR analysis is used to study the interactions between the chemical species. © 2017 Elsevier B.V. All rights reserved. Keywords: 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide 2-ethoxyethanol Redlich–Kister FT-IR 1. Introduction Ionic liquids (ILs), also known as green solvents, are a new class of solvents with unlimited applications in various disciplines [1–4]. The re- markable physico-chemical and recyclability properties of ILs, have made them popular “green” media for researchers [5–6]. The accurate selection of cation and anion, in the preparations of IL, enables to use it for a specific application [7]. Hence, ILs are also known as “designer solvents” having a large number of possible combinations of cation and anion. The peculiar properties of ILs like – negligible vapour pres- sure, more solvating capability, high electrochemical and thermal stabil- ity have made them “environmental friendly solvents” alternative to “volatile organic solvents” [8]. Further, the information about the physico-chemical properties of ionic liquid mixtures with other organic compounds is very much useful for various industrial applications. In continuation of our previous work on ILs and their binary mix- tures with organic solvents [9–12], in the present study, we have chosen the IL – 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([Bmim][NTf 2 ]) and 2- ethoxyethanol (2EE) binary mixture. The relatively low viscous na- ture of imidazolium based ILs can be used for easy handling and ad- equate performance in extractive applications. Hence, these ILs are more environment friendly than other ILs [13]. [Bmim][NTf 2 ] is a preferred ionic liquid as an electrolyte for capacitive energy storage and also in the process of nuclear fuel recycling [14]. The amphiphilic organic solvents like alkoxyethanols can be utilized in several chem- ical applications. The liquid mixtures having alkoxyethanols are im- portant due to the existence of –O– and –OH groups in the same compound. 2EE is used as a solvent in paints, surface coatings, inks and dyes. The thermodynamic behaviour of solutions are very much useful to obtain information on the intermolecular interactions and geometrical effects in the mixture systems. Furthermore, the knowledge of the ther- modynamic properties of binary mixtures is crucial for the proper de- sign of industrial processes. Thus, the accurate knowledge of thermodynamic properties of [Bmim][NTf 2 ] + 2EE binary mixture can be of great importance for their possible use in batteries, separation technology, catalysis, synthesis of nano objects etc. [15]. Journal of Molecular Liquids 251 (2018) 335–344 ⁎ Corresponding authors. E-mail addresses: tmadhumohan@gmail.com (T. Madhu Mohan), tvijayakrishna1980@gmail.com (T. Vijaya Krishna). https://doi.org/10.1016/j.molliq.2017.12.015 0167-7322/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq