Densities and viscosities were measured for the binary mixtures of 1,4-dioxane and 1,3-dioxolane with butyl acetate, butyric acid, butylamine, and 2-butanone at 298.15 K over the entire composition range. From density and viscosity data, the values of excess molar volume (V  E) and viscosity deviation (Δη) have been determined. These results were fitted to Redlich−Kister type polynomial equations. The density and viscosity data have been analyzed in terms of some semiempirical viscosity models.

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Here, we have investigated some physicochemical parameters to understand the molecular interactions by means of density (ρ) measurement, measurement of viscosity (η), refractive index(n D ) measurement, and conductance and surface tension measurements between two significant aqueous ionic liquid solutions: benzyl trimethyl ammonium chloride (BTMAC) and benzyl triethyl ammonium chloride (BTEAC) in an aqueous Lmethionine (amino acid) solution. The apparent molar volume (Φ v ), coefficient of viscosity (B), and molar refraction (R M ) have been used to analyze the molecular interaction behavior associated in the solution at various concentrations and various temperatures. With the help of some important equations such as the Masson equation, the Jones−Doles equation, and the Lorentz−Lorenz equation, very significant parameters, namely, limiting apparent molar volumes (Φ v 0 ), coefficient of viscosity (B), and limiting molar refraction (R M 0 ), respectively, are obtained. These parameters along with specific conductance (κ) and surface tension (σ) are very much helpful to reveal the solute−solvent interactions by varying the concentration of solute molecules and temperature in the solution. Analyses of Δμ 1 0# , Δμ 2 0# , TΔS 2 0# , ΔH 2 0#, and thermodynamic data provide us valuable information about the interactions. We note that L-Met in 0.005 molality BTEAC ionic liquid at 308.15 K shows maximum solute−solvent interaction, while L-Met in 0.001 molality BTMAC aqueous solution of ionic liquid at 298.15 K shows the minimum one. Spectroscopic techniques such as Fourier transform infrared (FTIR), 1 H-NMR, and UV−vis also provide supportive information about the interactions between the ionic liquid and L-methionine in aqueous medium. Furthermore, adsorption energy, reduced density gradient (RDG), and molecular electrostatic potential (MESP) maps obtained by the application of density functional theory (DFT) have been used to determine the type of interactions, which are concordant with the experimental observations.

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