Volumetric and Spectroscopic Studies of 1-ethyl-3-methylimidazolium Ethylsulfate/Propane-1-ol Binary Mixtures at Different Temperatures

Abstract

Binary mixtures of an ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate ([C2mim]C2H5SO4) with propane-1-ol were prepared over an entire composition range and density, dynamic viscosity, and refractive index at T = 293.15 to T = 333.15 K at atmospheric pressure were measured. The excess properties for the binary systems were determined and successfully fitted to a polynomial equation of the Redlich–Kister type. The variation of excess thermodynamic parameters predicted stronger intermolecular interactions and effective packing in the binary system compared to components. Thermodynamic activation parameters were also calculated from the Eyring equation, which varied with the concentration of [C2mim]C2H5SO4. The variation of these parameters also suggested the presence of strong heteromolecular interactions. The near-infrared (NIR) spectroscopic measurements were conducted in the temperature range from 293.15 K to 333.15 K and spectral variations were analyzed. The NIR data were further evaluated using principal component analysis (PCA) and two-dimensional (2D) correlation spectroscopy. The predicted molecular-level interactions mainly come from different types of HBs formed between unlike molecules in the binary system. The binary mixture may open up a plethora of possible uses due to its novel, distinctive molecular-level interactions, and favorable thermodynamic properties.