Enhancement of a Double Cosolvent on Solubility of [Bmim][Ac] and [Bmim][NTf₂] in Supercritical CO₂

Abstract

Solubility of 1-butyl-3-methylimidazolium bis-[(trifluoromethyl)sulfanilamide] ([Bmim][NTf 2 ]) and 1-butyl-3methylimidazolium acetate ([Bmim][Ac]) in supercritical carbon dioxide (scCO 2 ) using ethanol (EtOH) and ethylene glycol (EG) as a double cosolvent was measured at 40 °C and pressure from 8.0 to 15.0 MPa which was shown as the mole fraction of ionic liquids (ILs). The influence of ratios of EtOH to EG, pressures, concentrations of the cosolvent, and anions on enhancing the solubility of ILs in scCO 2 was investigated in this paper. The ability of the cosolvent with different ratios of EtOH to EG to enhance the solubility of [Bmim][Ac] followed the order y 1 /y 2 = 10:1 > y 1 / y 2 = 20:3 > y 1 /y 2 = 5:1 > y 1 /y 2 = 20:1. The maximum solubility of [Bmim][Ac] in scCO 2 was 5.6 × 10 −4 , which was about 30 times higher than its solubility using EtOH as a single cosolvent. The ability of the cosolvent with different ratios of EtOH to EG to enhance the solubility of [Bmim][NTf 2 ] followed the order y 1 /y 2 = 20:1 > y 1 / y 2 = 10:1 > y 1 /y 2 = 20:3. The maximum solubility of [Bmim][Ac] in scCO 2 was 2.4 × 10 −4 , about 1.5 times higher than its solubility using EtOH as a single cosolvent. The difference in ability to enhance solubility could be explained by solubility parameters. Finally, the modified Chrastil model, modified Meńdez-Santiago−Teja model, and modified Adachi−Lu model were employed to correlate the solubility data. The modified Chrastil model possessed the highest accuracy whose average absolute relative deviations were 2.88−7.06%.

Palladium Nanoparticles in Glycerol/Ionic Liquid/Carbon Dioxide Medium as Hydrogenation Catalysts

“…alkanes). 15,16 Concerning ionic liquids, Deep Eutectic Solvents (DES) have attracted great attention as reaction media in the last years, as an answer to the need of greener, less toxic, and non-volatile solvents. Interestingly, one of the most typical DES, i.e.…”

“…However, working in neat scCO 2 as solvent shows some limitations such as the low solubility of some reagents and catalysts. Combining compressed gas and liquid solvents (organic solvents, ionic liquids, deep eutectic mixtures), called gas-expanded liquids (GXLs), benefit from the advantages of both gas and liquid partners. , Furthermore, it is known that a number of ionic liquids can be dissolved in scCO 2 in the presence of polar compounds (such as acetone, ethanol, ethylene glycol); this effect is very restricted when apolar compounds are involved (e.g., alkanes). , Concerning ionic liquids, deep eutectic solvents (DESs) have attracted great attention as reaction media in the last years, as an answer to the need for greener, less toxic, and nonvolatile solvents. Interestingly, one of the most typical DESs, choline chloride/glycerol, has been reported to be comparable in cost to some organic solvents due to the wide availability of choline chloride and glycerol .…”