Liquid densities and excess molar volumes for (ionic liquids + methanol + water) ternary system at atmospheric pressure and at various temperatures
Introduction
An ionic liquid is defined as a material containing only ionic species. Most of the organic ionic liquids are the combinations of a 1-butyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium or n-butylpyridinium cation and a charge diffuse inorganic anion [1] so they are also called as “designer solvents” [2], [3]. Ionic liquids have been found to be viable reaction media for numerous types of reactions [4]. Ionic liquids have also received attention from both the industrial and academia in research as diverse as electrochemistry, catalysis, synthesis, biotechnology, and material separations [5], [6], [7], [8], [9]. Ionic liquids are also used as catalyst for the most important carbon–carbon bond forming reaction called Diels–Alder reaction [10]. These are also used as solvents for green chemistry [11], [12].
This is all due to their unique physical and chemical properties such as thermal stability, high solubility for polar and non-polar organic and inorganic substances. Moreover, there exist very few reliable data of liquid densities and excess molar volumes of multi component systems on ionic liquids in literature. Moreover, these thermophysical data of multicomponent systems are used for the design of several type of relevant industrial equipments and many industrial applications like design calculation, heat transfer, and fluid flow. Moreover, these properties can provide an important tool to extract information about the state of aggregation of components in pure as well as in mixed state and also about the nature and extent of interactions operating between the constituents of systems. We have analysed the densities and molar excess volumes of {[EMIM][CH3(OCH2CH2)2OSO3] + water + methanol} ternary system. This work is a continuation of our previous study [13]. In our earlier work, we have reported the densities and molar excess volumes of binary systems containing ionic liquid and water or methanol.
Section snippets
Experimental
The 1-ethyl-3-methyl-imidazoliumdiethylenglycolmonomethylethersulphate was used without further purification. Methanol was dried by refluxing with Grignard reagent (Mg + I2) for 6 h and then distilled over freshly activated 4 nm molecular sieves. Doubly distilled water was used.
Ternary system was prepared by mass using a Mettler mass balance (Switzerland, model AE-200) with an accuracy of ±0.0001 g. The more volatile component was filled directly into the air-tight Stoppard 5 cm3 glass vial, and then
Results
Molar excess volumes, for ternary system was calculated from experimental densities using the following equation:where x1, x2, and x3 are mole fractions, M1, M2, and M3 denote molar masses, ρ1, ρ2, and ρ3 are the densities of the pure components 1, 2, and 3, respectively, and ρ the density of the ternary system. Experimental densities and the calculated excess molar volumes are given in TABLE 2, TABLE 3, TABLE 4.
Excess molar volumes were then
Discussion
There are no literature values of for the studied ternary systems to compare our results. The densities of the pure ionic liquid as well as of their system decreased with an increase in temperature. In interpreting in terms of molecular interactions, positive values can be explained by the breaking of intermolecular interactions in the pure components during the mixing process. Negative is due to a more efficient packing and/or an attractive intermolecular interaction in the
Acknowledgement
The authors thank the National Research Foundation (South Africa) for financial support.
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