Phase Equilibria and Modeling of Pyridinium-Based Ionic Liquid Solutions

Abstract

The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM(4)Py][NTf(2)]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM(4)Py][NTf(2)] with all solvents reveal eutectic systems with regards to (solid-liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid-liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridinium-based ILs. The influence of the anion of the IL on the phase behavior has been discussed.

Thermodynamic properties of the N-butylisoquinolinium bis(trifluoromethylsulfonyl)imide

“…The interaction between the IL and the solvent is most likely due to p-p interactions between two aromatic rings of the cation of the IL and of the solvent. On the other hand, the solubility of aromatic hydrocarbons in [BiQuin][NTf 2 ] is lower than was measured by us earlier for 1-hexyloxy-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [C 6 [13]. This comparison does not provide optimism for the quinolinium-based ILs to be used for the separation process of aromatic hydrocarbons from aliphatic hydrocarbons.…”

“…For all ILs with the same anion, [NTf 2 ] À , including quinoliniumbased [8][9][10], or pyridinium-based [13,14], or imidazolium-based [15,16], similar dependences of decreasing solubility in alcohols with an increase of the carbon chain length of an alcohol is observed. Usually, the UCST decreases with an increase of an alkyl chain length at the cation.…”

Combined phase behavior, dynamic light scattering, viscosity and spectroscopic investigations of a pyridinium-based ionic liquid-in-oil microemulsion

“…However, there has been a recent trend to search for easily available and low-cost alternative ILs other than the imidazolium ion. According Domanska et al, 10 pyridiniumbased ILs have specic properties, viz., broad temperature range in the liquid state, inertness to air, moisture and superior solubilization capacity. These unique features of pyridiniumbased ILs have already been explored with special reference to antistatic thermoplastic resins, 11 adhesive lms, 12 electrochemical probes, 13 electron transfer processes, 14 reaction acceleration, 15 organocatalysis, 16 extraction processes, 17 etc.…”

How to select ionic liquids as extracting agents systematically: a special case study for extractive denitrification processes

“…The modified Flory–Huggins equation and a lattice model based on polymer solution models are also adopted to well-describe the phase diagrams. 33 The group contribution methods like UNIFAC and its modified variants are also employed to correlate the thermodynamic properties and LLE in ILs. 18 However, the key disadvantage of aforesaid models is their limited applications specifically for ILs due to lack of required parameters for most of ILs.…”