Investigation of Physico-chemical Properties for the 1-Butyl-3-methylimidazolium Tetrafluoroborate ([Bmim][BF₄])–Diethylenetriamine (DETA) System for CO₂ Capture

This paper presents the experimental values of densities, viscosities and refractive indices for 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF₄])–diethylenetriamine (DETA) mixtures over the entire composition range and temperature range 298.15–333.15 K. The physico-chemical properties such as excess molar volume, partial molar volume, partial molar volume at infinite dilution, apparent molar volume, apparent molar volume at infinite dilution, isobaric thermal expansion coefficient and excess isobaric thermal expansion coefficient were calculated from the experimental density data. The excess Gibbs energy and excess entropy of flow were determined from the viscosity data using Eyring’s theory of rate process. The specific interactions between molecules in mixtures were explained by analyzing the behavior of the thermodynamic excess/deviation properties. To determine the correlating accurately with the utilized models including the Redlich–Kister, modified Graber, Lorentz–Lorenz and McAllister equations, the adjustable parameters and standard deviations were determined. Moreover, the qualitative analysis of these properties was further legitimized with Fourier-transform infrared (FTIR) spectroscopic studies.