The mixture of acetonitrile (1) + n-propanol (2) forms a binary azeotropic mixture at atmospheric pressure, which cannot be separated by common distillation. In this paper, the ionic liquids ( ILs) 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) were used as solvents for separating the binary azeotropic mixture. The ternary isobaric vapor−liquid equilibrium data of acetonitrile (1) + n-propanol (2) + ILs (3) at atmospheric pressure in three IL mole fractions of 0.048, 0.091, and 0.131 were obtained. The results showed that the addition of [MMIM][DMP] or [EMIM]-[DEP] could enhance the relative volatility of acetonitrile to npropanol, and the azeotropic point of the binary azeotropic system could disappear at the mole fractions of ILs abovementioned. The effect of separation of ILs was in the order of [EMIM][DEP] > [MMIM][DMP]. The interaction parameters were obtained by fitting the nonrandom two-liquid (NRTL) model to the binary vapor−liquid equilibrium experimental data.The predicted results obtained using the NRTL model were in good agreement with the experimental data. In addition, a quantum chemical calculation based on Gaussian 09 at the B3LYP/6-311++G** level was also conducted. The calculated results indicated that the molecules of ILs had a stronger interaction with the n-propanol molecule than with the acetonitrile one.

Isobaric vapor-liquid equilibrium (VLE) data of the ternary system acetone + chloroform + 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) or 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) were obtained at 101.3 kPa. Results indicated that the addition of [MMIM][DMP] or [EMIM][DEP] could eliminate the azeotropic point of the binary system of acetone + chloroform when the mole fraction of ionic liquids (ILs) was above 0.15. Besides, the experimental data could be well correlated by the nonrandom two-liquid (NRTL) model. The structures as well as interactions between molecular solvents (acetone, chloroform) and the ion pairs ([MMIM][DMP], [EMIM][DEP]) were studied by quantum chemical calculations. The result indicated that the interaction energies (ΔE) follow the order of ΔE(acetone + [EMIM][DEP]) > ΔE(acetone + [MMIM][DMP]) > ΔE(chloroform + [EMIM][DEP]) ≈ ΔE(chloroform + [MMIM][DMP]), and chloroform had stronger affinity to ionic liquids than acetone.

Eccentrically braced frame (EBF) incorporates the advantages of lateral resisting systems from moment resisting frame (MRF) and concentrically braced frame (CBF) into a single structural system. In order to investigate the effects of brace and link length in resisting progressive collapse, a finite element model of 10-story planar steel frame were built and analyzed with the SAP2000 software through nonlinear static analysis and nonlinear dynamic analysis respectively. The results show that brace can obviously improve the performance of the structure no matter which kind of brace is adopted. The inverted V-shaped (IV) eccentrically braced frame has the highest capacity against progressive collapse and the Y-shaped eccentrically braced frame has the highest energy absorption capacity of the structure. Increasing the link length leads to an increase in deformation and energy absorption of the structure. The results of nonlinear static analysis could reflect the structural performance basically.