Abstract
In this work, new data for the binary mixtures containing 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim] [BF4]) ionic liquid (IL) with benzaldehyde or ethyl acetoacetate were investigated under atmospheric pressure (p = 0.1 MPa) and at temperatures (293.15-313.15) K. The binary mixtures were completely miscible at all proportions. Densities ( ρρ<math><mrow><mi>ρ</mi></mrow> </math> ), viscosities ( ηη<math><mrow><mi>η</mi></mrow> </math> ) as well as speeds of sound (u)(u)<math> <mrow><mrow><mo>(</mo> <mrow><mi>u</mi></mrow> <mo>)</mo></mrow> </mrow> </math> were conducted across the entire range of mole fraction ( xixi<math> <mrow> <msub><mrow><mi>x</mi></mrow> <mrow><mi>i</mi></mrow> </msub> </mrow> </math> = 0 to 1). The excess properties which include excess molar volumes (VEm)(VmE)<math><mrow><mspace></mspace> <mrow><mo>(</mo> <msubsup><mrow><mtext>V</mtext></mrow> <mrow><mtext>m</mtext></mrow> <mrow><mtext>E</mtext></mrow> </msubsup> <mo>)</mo></mrow> </mrow> </math> , intermolecular free length ( LfLf<math> <mrow> <msub><mrow><mi>L</mi></mrow> <mrow><mi>f</mi></mrow> </msub> </mrow> </math> ), deviations in viscosity ( ΔηΔη<math><mrow><mtext>Δ</mtext> <mi>η</mi></mrow> </math> ), isentropic compressibility (ks)(ks)<math><mrow><mo>(</mo> <msub><mrow><mi>k</mi></mrow> <mrow><mi>s</mi></mrow> </msub> <mo>)</mo></mrow> </math> , apparent molar isentropic compressibility ( KϕKϕ<math> <mrow> <msub><mrow><mi>K</mi></mrow> <mrow><mi>ϕ</mi></mrow> </msub> </mrow> </math> ) as well as deviation in isentropic compressibility (Δks)(Δks)<math><mrow><mspace></mspace> <mrow><mo>(</mo> <mrow><mo>Δ</mo> <msub><mrow><mi>k</mi></mrow> <mrow><mi>s</mi></mrow> </msub> </mrow> <mo>)</mo></mrow> <mspace></mspace></mrow> </math> were determined from the experimentally found results of speed of sound, viscosity and density. The obtained derived properties have been elucidated in terms of solute-solvent interactions taking place in the systems. The investigation of thermophysical properties of organic solvents with ionic liquids is essential as they decide the transformation of ionic liquids from small laboratory scale to large industrial applications. The obtained results are important and essential as they describe the molecular interactions, and can be used in constructing the structure-property correlation as well as molecular modelling that exist between [C2mim] [BF4] with benzaldehyde or ethyl acetoacetate. Redlich-Kister polynomial equation was used to fit the excess values and a good correlation was achieved.