Influence of epoxy group in 2-pyrrolidonium ionic liquid interactions and thermo-physical properties with Ethanoic or Propanoic acid at various temperatures

Abstract

In this present study, the interaction between a carboxylic acid and ionic liquids, in terms of their binary mixtures and corresponding thermo-physical properties, was investigated. Here, the novel ionic liquid (IL) [EPMpyr]+[Cl]− was synthesized, and it has been mixed with ethanoic or propanoic acids. The influence of the epoxy group in this ionic liquid was more strongly affected with the acids, and their physicochemical properties at varied temperatures are discussed in term of density (ρ), viscosity (η), speed of sound (u), and refractive index (n) measurements. The density (ρ), speed of sound (u), viscosity (η), and refractive index (n) of the IL, ethanoic acid, propanoic acid, and their corresponding binary mixtures {[([EPMpyr]+[Cl]− (1) + ethanoic or propanoic acid (2)} have been measured at T = (293.15–313.15) K and at P = 0.1 MPa. The theoretical thermodynamic properties of excess molar volumes (VmE), isentropic compressibility (ks), deviation in isentropic compressibility (Δks), and intermolecular free length (Lf) are calculated using experimental density and speed of sound data. The VmE and Δks values for both binary mixtures were found to be negative over the entire mole fraction range of composition at all the investigated temperatures. These results suggest the existence of specific interactions between components in the molecules. The experimental data could be helpful to understand the molecular interactions between the IL and carboxylic acid combinations. The experimental data were fitted to the Redlich–Kister polynomial equation.