Thermodynamic Properties of Binary Mixtures Containing Ionic Liquid 1-Butyl-3-methylimidazolium Thiocyanate and Ethanolamines at Different Temperatures: Measurement and PC-SAFT Modeling

Thermodynamic properties of liquid absorbents are important for industrial applications. Ionic liquids (ILs) are more efficient alternatives to organic solvents that are used for CO2 absorption and storage. The IL, 1-butyl-3-methylimidazolium thiocyanate ([BMIM] [SCN]) with ethanolamines are considered as an efficient material for gas absorption. The density and speed of sound for a full-range concentration of binary ([BMIM] [SCN] + ethanolamine (MEA)/diethanolamine (DEA)/triethanolamine (TEA)) systems have been measured at (288.15 - 318.15) K, and excess molar properties as nonideality of the mixtures has been calculated. The conductor-like screening model (COSMO) as a microscopic approach has been used to calculate the PC-SAFT equation of state parameters, prediction the density of the studied mixtures, and compare the experimentally obtained parameters of PC-SAFT. The excess molar volumes for systems containing IL + monoethanolamine are positive while negative for DEA and TEA. Also, the excess isentropic compressibilities for the studied mixtures are negative at all temperatures. The PC-SAFT equation of state as a microscopic approach for interpreting the molecular interactions is an efficient model in predicting thermodynamic properties. The results indicate that increasing OH groups of ethanolamines enhances their interactions with IL molecules.