Study On The Physico-chemical Properties Of Lactate Ionic Liquids And Its Aqueous Solutions

As a green, designable and environmentally friendly solvent, the worldinfluence of the ionic liquid in the application and research field is very extensive.Its many advantages, such as polarity adjustable, green catalysis, providingnon-water environment, let us have the premise of studying the physicochemicalproperties of ionic liquid.In this paper we use lactic acid ionic liquid as the studysubject, using the thermodynamic properties out of its physicochemical properties,we completed the following work:The [C₂mim [Lact]（1-ethyl-3-methyl-imidazole lactate） and [C₅mim][Lact]（1-pentyl-3-methyl-imidazole lactate）, which are the two ionic liquids, havebeen synthesized, and characterized on purity by1H NMR, TGA and differentialthermal scanning calorimetry （DSC）, respectively.Using the standard addition method （SAM） to these two lactic acid ionic liquids,under the case of different water content, we measured the surface tension, refractiveindex and density of ionic liquids in the temperature range of283.15K-338.15K,and also got the surface tension, refractive index, density and molecular volume Vmof the ionic liquids without water in the same temperature range. Meanwhile, weused molecular volume to estimate the surface energy Ea, the surface entropy Saofionic liquids, and using the empirical equation we estimated the enthalpy ofvaporization of the lactic acid ionic liquids lgHmθ, taking the the above work as thefoundation, we estimated the density, standard entropy, lattice energy of the sameseries of the lactic acid ionic liquids as [C_nmim][Lact]（n=2,3,4,5,6）; and wealso estimated the surface tension and the molar enthalpy of vaporization of[C_nmim][Lact]（n=2,3,4,5,6） reasonably and scientifically, using thecharacteristic of additivity of the parachor and the basis of experimental data.After the refractive rate measurement of the ionic liquid had been done, themolar polarization and polarization rate of these two ionic liquids were alsocalculated. Since the purity of ionic liquids have a great impact on their physicochemicalproperties, we measured the density and surface tension of the solution of ionicliquids of [C₂mim][Lact] and [C₅mim][Lact] in the concentration range of0.10000.5000mol/kg and in the temperature range of283.15K-338.15K. We alsoused the empirical formula of the parachor for determining the surface tension of theaqueous solution of ionic liquid in the temperature of298.15K and this turned out tobe fairly reasonable.