Experimental Determination Of Physicochemical Properties For Binary Mixtures Of Ionic Liquid With Alcohols And Its Semi-empirical Estimation

Ionic liquids?ILs?have been attracted much attention from both academic and industrial communities for their unique properties.The pyridinium-based ILs is very typical among ILs.It not only has the characteristics of ionic liquids,but also has low cost,low toxicity and good adsorption capacity of sulfur dioxide.It is also believed that ILs with ether on imidazole cation may have special properties than that with non-ether functionalized ionic liquids.In order to further study the properties of ether based ionic liquids,a hydrophobic ionic liquid with bis?trifluoromethylsulfonyl?imide was designed.The microstructure and physicochemical properties of ionic liquids can be changed by adding solvent and other substances in pure ionic liquids.Therefore,the study for binary mixtures of ionic liquid with other solvents is not only an effective supplement to the design of ionic liquids,but also expand the application range of ionic liquids.So,the followings were reported in this paper:1.Three kinds of ionic liquids were synthesized by the method of complex decomposition,whichwere1-ethyl-pyridiniumdicyanamide[C₂py][DCA],1-butyl-pyridiniumdicyanamide[C₄py][DCA]and1-methoxyethyl-3-methyl imidazoliumbis?trifluoromethylsulfonyl?imide[MOEMIM][NTf₂].Theywere characterized by ¹H NMR spectroscopy?¹³C NMR spectroscopy and elemental analysis.The synthesized products were determined to be the target ionic liquids.2.For the first time,the values of density,surface tension and viscosity of binary mixtures for[C₂py][DCA]with alcohols?ethanol,1-propanol and 2-propanol?,[C₄py][DCA]with alcohols?ethanol,1-propanol and 2-propanol?and[MOEMIM][NTf₂]with alcohols?methanol and ethanol?were measured over the entire composition range?x₁=0.0000¹.000?at T=?288.15 to 318.15?K interval 5K.3.The volume properties of binary mixtures are discussed.The results show that average molar volume increases with increasing temperature and molar fraction.In order to elucidate the solute–solvent interactions,excess molar volumes,V ^E,were fitted by Redlich-Kister equation.It shows that the excess molar volumes are all negative and asymmetric over the entire composition range.The interaction between ionic liquid and alcohol is the strongest efficient packing and/or attractive interaction at the minimum point.The interaction between ionic liquid and alcohol molecule is not only related to the polarity of alcohols,but also to the polarity of ionic liquids.Moreover,the excess molar volumes decrease with increasing temperature.4.For the first time,thermodynamic model of surface tension for binary mixtures over the entire composition range was obtained from Li's model improved in this work and the new function-the molar surface Gibbs energy of mixtures,g_s,was proposed.On a basis of g_s,surface properties of binary mixtures were discussed.The values of g_s^E were fitted by Redlich-Kister equation.The values of g_s^E are negative over the whole composition range.The values of g_s^E are the smallest at the minimum point,which indicates that ionic liquids have a stronger influence on the surface properties of the mixtures.5.On a basis of molar surface Gibbs energy of mixtures,a new E?tv?s equation was obtained and applied to binary mixtures for ionic liquids with alcohols.Compared with the traditional E?tv?s empirical equation,each parameter of the new E?tv?s equation has a clear physical meaning.6.Although??can reflect the viscosity deviations between the actual mixture and the corresponding ideal mixture,it is not related to the corresponding excess Gibbs energy of activation.So,in terms of a new concept-the relative viscosity,?_r,of mixture proposed in this work and a correct equation of excess Gibbs free energy of activation,?G^?E,for viscous flow of mixture was derived.The values of?G^?E were calculated and well fitted by a Redlich-Kister equation.7.By using the values of Redlich-Kister parameters A_i,a new method for estimating average molar volume,surface tension and viscosity with any component for binary mixtures is proposed and the estimated values by using semi-empirical method are in good agreement with the corresponding experimental ones.