Determination of vaporization enthalpy for ionic liquids [Cnmim][Lact] (n=2, 3, 5) and applications of the molar surface Gibbs free energy

作者：Wei, Jie; Li, Zhe; Gu, Chuang; Pan, Yi; Xing, Nan-Nan; Tong, Jian; Guan, Wei^*

来源：Journal of Thermal Analysis and Calorimetry, 2016, 125(1): 547-556.

DOI：10.1007/s10973-016-5318-9

• Lactic acid ionic liquids
• Vaporization enthalpy
• Molar surface Gibbs free energy
• Eotvos equation

Lactic acid ionic liquids 1-alkyl-3-methylimidazolium [C(n)mim][Lact] (n = 2, 3, 5) were prepared and confirmed. The enthalpy of vaporization, , at the average temperature, T (av), for the three ILs was determined using isothermogravimetrical analysis, and in terms of , the value of can be transformed into ; then, according to the scale of polarity, delta (mu), the polarity of the three ILs was estimated, in which the order of the polarity is in accordance with our experiences. Moreover, a new thermodynamic quantity-molar surface Gibbs free energy, g (s)-is derived from the improved Tong's vaporization enthalpy model. In terms of g (s), the traditional Eotvos equation was improved to be a new Eotvos one, in which the parameters have clear physical meanings: Its slope is molar surface entropy, s, and the intercept is the molar surface enthalpy, h. In addition, combining g (s) with Lorentz-Lorenz equation, an expression for predicting surface tension of the ILs was obtained, and the predicted values of surface tension are in good agreement with the experimental ones.

• 出版日期2016-7
• 单位辽宁大学