Studies on the interference of citrate salts on the ion–solvent interactions of ionic liquid with water at different temperatures through volumetric, viscometric, and acoustic methods

Abstract

The density, viscosity, and ultrasonic velocity of solutions of imidazolium-based ionic liquid, 1-ethyl-3-methyl imidazolium ethyl sulphate ([EMIm][EtSO4]) with aqueous solutions of sodium and potassium salts of citrate have been measured at five different temperatures i.e., T = (298.15–318.15) K and 0.1 MPa pressure. The experimentally found density (ρ) data have been utilized to compute the different volumetric properties such as apparent molar volume (Vϕ), partial molar volume (Vϕ0), partial molar expansivity (Eϕ0), Hepler’s constant (∂Eϕ0/∂T)p and volume transfer (ΔtrVϕ0). Similarly, the Jones-Dole equation, viscosity B-coefficient, transfer properties of B-Coefficient, (ΔtrB) and thermodynamics of viscous flow were calculated from viscosity consequences. The compression properties such as apparent molar isentropic compressibility (Kϕ,S), partial molar compressibility (Kϕ,S0) and transfer partial molar compressibility (ΔtrKϕ,S0) of IL have been deduced from the ultrasonic velocity. All the derived properties have been used to investigate the impact of citrate salts on the ion–solvent interactions of [EMIm][EtSO4] with water. The positive value of each of Hepler’s constants, and ΔtrKϕ,S0 and the negative sign of (dB/dT) indicates the existence of strong ion–solvent interactions and the cosmotrope nature of [EMIm][EtSO4] in the studied systems at the studied temperature ranges. The ion–solvent interactions of the present IL are found to be more in the solutions of potassium citrate (K3Cit) than sodium citrate (Na3Cit).