Composition and Temperature Dependence of Density, Surface Tension, and Viscosity of EMIM DEP/MMIM DMP + Water + 1-Propanol/2-Propanol Ternary Mixtures and Their Mathematical Representation Using the Jouyban–Acree Model

Abstract

Room temperature ionic liquids (RTILs) have been ascribed as alternative solvents in separation processes or chemical reactions. This research is concerned with the study of density, ρ, viscosity, η, and surface tension, σ, over the mole fractions of (0.1000 to 1.000) mol and temperature from (293.15 to 333.15) K for ternary mixtures of 1-ethyl-3-methylimidazolium diethylphosphate (EMIM DEP)/1,3-dimethylimidazolium dimethylphosphate (MMIM DMP), water, and 1-propanol/2-propanol. As the temperature increased, surface tension and density results for all the multicomponent mixtures show a linear descending trend. Adversely, viscosity results indicate polynomial descending trend. At the whole ranges of temperature, the density, surface tension and viscosity data show a significant gap between mole fractions of ionic liquid. These experimental results have been evaluated and the most prominent polynomial or linear regressions were obtained. The most prominent correlation for density and surface tension for all four systems were obtained using a linear equation. In contrast, the best correlation for viscosity data was obtained using a second order polynomial equation. On the other view, the experimental density and surface tension data decrease linearly with mole fraction of ionic liquid. The Jouyban−Acree model was used to correlate the density, surface tension, and viscosity of the studied mixtures at different temperatures. The accuracy of the model was evaluated and the absolute percentage error (APER) for each correlation was less than 6%.

Volumetric behaviour of six ionic liquids from T = (278 to 398) K and up to 120 MPa

“…It is well known that the viscosity of ILs is drastically affected by the presence of water as well as other volatile impurities. Nevertheless, the viscosity value obtained by Normazlan et al [27] for a sample with water content of 2800 Â 10 À6 is higher than those measured by us and by other authors [28,29] for samples with lower water contents.…”

“…Zhang et al [28] have used a sample of this IL with a water content of 156 Â 10 À6 and an automatic falling ball viscometer with an uncertainty of 5 Â 10 À3 mPa Á s. Besides, He et al [29] used a sample with a water content of 170 Â 10 À6 and a capillary viscometer but they do not report the uncertainty of the measurements. The deviations among the values obtained by different authors range from (7.5 to 38)%, being the higher deviation between Normazlan et al [27] and Zhang et al [28]. The viscosity value reported in table 1 agrees within 14% with Zhang et al [28] and 21% with He et al [29].…”

“…C is a constant parameter, and B(T/K) is a polynomial function of temperature: The density of the six analysed ILs was previously measured by other authors mainly at atmospheric pressure [27,28,. Figure 2 shows the deviations between literature experimental densities, q exp and correlated densities, q corr , obtained with equation (2) [60].…”

“…For [C 1 C 1 Im] [(C 1 O)2 PO 2 ] we have found an excellent agreement with Zhang et al[28] and with Palgunadi et al[37] being (0.02 and 0.10)% the AADs%, respectively, despite the viscosity of the Palgunadi et al sample is 14% higher than that of our sample. The highest relative deviation (0.9%) is found with densities of Normazlan et al[27]. These authors have studied a sample with 0.28% water content whereas the water content of our sample is 507 Â 10 À6 .For [C 2 C 1 Im][C 6 SO 4 ] and [C 4 C 1 Pyrr][CF 3 SO 3 ], all the deviations with the experimental literature densities are within the combined uncertainty of our apparatus and those from the literature [36,42-44,48-53].…”

“…Three of them containing the cation 1-butyl-1-methylpyrrolidinium: 1-butyl-1-methylpyrrolidinium tetracyanoborate, [C 4 [27] have studied a sample with a water content of 2800 Â 10 À6 . These authors used a Rheometer Brookfield with an uncertainty of 1%.…”