Density, viscosity, conductivity, refractive index and interaction study of binary mixtures of the ionic liquid 1–ethyl–3–methylimidazolium acetate with methyldiethanolamine

A new binary mixture system of ionic liquid 1–ethyl–3–methylimidazolium acetate ([Emim][Ac]) and methyldiethanolamine (MDEA) (IL   +   alkanolamine) were prepared. The physico–chemical properties of density, viscosity , electrical conductivity , and refractive index for the mixtures were determined from 288.15   K to 353.15   K. By the Vogel–Fulcher–Tamman (VFT) equation and Arrhenius equation , the temperature dependences of the viscosities and electric conductivities for the system were graphically described and the VFT equation showed better correlation for the system. To investigate the internal interactions of the mixtures, the excess volume and DFT calculations were employed. The trend of excess molar volumes showed more efficient packing structures due to the increase of interactions in the mixed system with the increasing of temperature. Further, the structures, the energetics , and charge distribution of all ions and molecules involved in interactions were estimated by DFT calculations combining the COSMO–RS methodology to describe intermolecular interactions between the [Emim][Ac] and MDEA.