Search

Three propionic acid ionic liquids (PrAILs), 1-alkyl-3-methylimidazolium propionate ([Cnmim][Pro] (n = 4, 5, 6)), were prepared by the neutralization method and characterized by 1H NMR spectroscopy. The values of the densities and surface tensions of aqueous [C4mim][Pro], [C5mim][Pro], and [C6mim][Pro] with various molalities were determined at 298 K, and the values of the parachor for these solutions were calculated. The values of the apparent molar volumes and partial molar volumes at infinite dilution for the ILs were estimated in terms of Pitzer’s theory. With the use of Li’s model of surface tension and the empirical equation of the parachor, the values of the surface tensions of these aqueous solutions for three PrAILs were estimated and the estimated values were in good agreement with experimental ones.

Four propionic acid ionic liquids (PrAILs) [Cnmim][Pro] (n = 3, 4, 5, 6) (1-alkyl-3-methylimidazolium propionate) were prepared by the neutralization method and characterized by 1H NMR spectroscopy and differential scanning calorimetry. The values of their density, surface tension, and refractive index were measured in the temperature range of 288.15–328.15 K. Since the PrAILs can strongly form hydrogen bonds with water, the small amount of water is difficult to remove from the PrAILs by conventional methods. To eliminate the effect of the water impurity, the standard addition method (SAM) was applied to these measurements. The dependence of volumetric properties, surface properties, and molar refraction on temperature were discussed. In terms of Kabo’s method the molar enthalpies of vaporization, ΔHV, for the PrAILs were estimated. As a new idea, it was put forward that ΔHV can be assumed to consist of two parts: one is the contribution from induced dipole, ΔHVn, and the other is the contribution from th...

The ionic liquids based on lactic acid (LAILs)—1-ethyl-3-methylimidazolium lactate ([C2mim][Lact]) and 1-pentyl-3-methylimidazolium lactate ([C5mim][Lact])—have been prepared by the neutralization method and characterized by 1H nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The values of their density, surface tension, and refractive index were measured at 298.15 ± 0.05 K. Since the LAILs can form strong hydrogen bonds with water, small amounts of water are difficult to remove via common methods. In order to eliminate the effect of the impurity water, the standard addition method (SAM) was applied to these measurements. An improved semiempirical method to estimate the properties of the ILs has been put forward; that is, in terms of an extrathermodynamic assumption, the values of the individual ion volume, [C2mim]+ and [BF4]−, were successfully evaluated from the molecular volume of the IL [C2mim][BF4]. Then, using [C2mim]+ as the reference ion, the properties of [Lact]− and ...

A new ionic liquid [C3mim][Val] (1-propyl-3-methylimidazolium valine) was synthesized and characterized by 1H NMR. To avoid the influence of trace water in the ionic liquid (IL), the standard addition method (SAM) was employed; the density and surface tension of the [C3mim][Val] were determined over the temperature range of 303.15–333.15 K (±0.05 K). The experimental density, surface tension, and parachor values at 298.15 K are in good agreement with that predicted by Tong et al. [J. Tong et al., Ind. Eng. Chem. Res.2011, 50, 2418–2423]. Based on the experimental data for [C3mim][Val], a series of physicochemical properties—the molecular volume (Vm), surface tension (γ), refractive index (nD), molar enthalpy of vaporization (ΔlgHm0), the thermal expansion coefficient (α) values, the standard molar entropy (S0), and the molar polarization (Rm)—for the homologue of [Cnmim][Val] (n = 2, 4, 5, 6) were estimated using the empirical methods. The estimated results are consistent with one of Tong’s estimations, i...

The densities, viscosities, and conductivities were measured for the ternary solution NaCl + urea + H2O, the quintuple solution NaCl + Na2SO4 + KCl + K2SO4 + H2O, and their binary subsystems at 298.15 K. The results together with the densities, viscosities, and conductivities of multicomponent solutions reported in the literature were used to study the predictability of the Young’s rule for density and conductivity, the rule of Patwardhan and Kumar for density, Hu’s equation for the viscosity of mixed electrolyte solutions based on the Eyring’s absolute rate theory and the rule of Patwardhan and Kumar, and the semiideal solution theory for thermodynamic and transport properties. The results show that all the tested equations can provide comparable and accurate predictions for the densities of multicomponent electrolyte solutions. The semiideal solution theory is applicable to the aqueous solutions of electrolytes and nonelectrolytes, and its predictions for the densities of the examined solutions are in n...