A comparative study of ammonia solubility in imidazolium-based ionic liquids with different structural compositions

The thermophysical properties (decomposition temperature, glass transition temperature, density, and viscosity) of imidazolium-based ionic liquids (ILs) paired with the tricyanomethanide ([TCM]−) anion and the bis(trifluoromethylsulfonyl)imide ([Tf2N]−) anion were studied within a wide temperature range. The effect of the ether functional group (in [Tf2N]− and [TCM]− ILs) and hydroxyl functional group (in [Tf2N]− IL) incorporated in the cation’s alkyl chain on the thermophysical behavior and carbon dioxide (CO2) solubility was evaluated by comparing their behavior to the corresponding nonfunctionalized ILs. The thermal stability was enhanced by the inclusion of hydroxyl functionalization in the cation’s alkyl chain while ether functionalization had no major effect on the thermal stability. The ether groups (one or two) resulted in an increase in the density and a decrease in the viscosity of all ILs. The hydroxyl group resulted in an increase in both properties. The CO2 solubilities were not affected by the presence of the ether groups, while the hydroxyl group led to a significant decrease in the solubility. Additionally, the electrolyte perturbed-chain statistical associated fluid theory (ePC-SAFT) equation of state was used to calculate the CO2 solubility in the ILs and the Henry’s law constant. The model showed great predictive ability. The Henry’s constants were applied to calculate the partial molar thermodynamic properties of solvation.

In response to the increasing global demand for energy and the limitations of conventional oil recovery methods, this study investigates the potential of imidazolium-based ionic liquids (ILs) as novel agents for enhanced oil recovery (EOR). The effects of four imidazolium ILs1-decyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium tetrafluoroborate, and 1-hexadecyl-3-methyl imidazolium bromide (C16mimBr)on phase behavior, interfacial tension (IFT), and wettability between oil, water and rock were examined in the context of Emirati tight oil reservoirs. In addition, the thermal stability of these ILs was investigated under extreme temperatures of up to 600 °C using thermogravimetric analysis. Experiments were conducted across a range of temperatures (up to 110 °C), IL concentrations (0, 500, 1500, and 3000 ppm), and salinities (seawater and formation brine). In particular, the IL with the longer alkyl chain (C16mimBr) effectively reduced the IFT by >99% in formation brine at 3000 ppm and 110 °C and altered contact angles to as low as 15.37°. Emulsification experiments were conducted with the emulsions analyzed under a microscope to measure the size of water droplets within the microemulsions. It was observed that all imidazolium ILs tested at 500 ppm successfully stabilized oil/brine emulsions, maintaining complete phase integrity for at least 48 h. Imidazolium ILs with longer chains and bulky anions (C12mimBF4) showed adsorption as low as 2.71 mg/g, reducing chemical loss and enhancing EOR effectiveness. The findings indicate that the choice of IL and its concentration significantly impact the economic reduction of IFT and optimize EOR processes.

Herein, we report an efficient and facile strategy for the preparation of imidazolium-based ionic liquid (IL) monomers ([CnVIm][Br], n = 2, 4, 6, 8, 10, and 12) and their corresponding polymeric ionic liquids (PILs) with potent antimicrobial activities against Gram-negative and Gram-positive bacteria and fungi. The electrospinning technique was utilized to tailor the polymers with the highest antimicrobial potency into porous membranes that can be easily implemented into diverse systems and extend their practical bactericidal application. The antimicrobial mechanism of obtained ILs, polymers, and nanomaterials is considered concerning the bearing chain length, polymerization process, and applied processing technique that provides a unique fibrous structure. The structure composition was selected due to the well-established inherent amphiphilicity that 1-alkylimidazolium ILs possess, coupled with proven antimicrobial, antiseptic, and antifungal behavior. The customizable nature of ILs and PILs complemented with electrospinning is exploited for the development of innovative antimicrobial performances born from the intrinsic polymer itself, offering solutions to the increasing challenge of bacterial resistance. This study opens up new prospects toward designer membranes providing a complete route in their designing and revolutionizing the approach of fabricating multi-functional systems with tunable physicochemical, surface properties, and interesting morphology.

Potassium-ion batteries (K-ion batteries; KIBs) are attractive as high-voltage, low-cost energy storage devices. Ionic liquids (ILs) are potential candidates as safe and high-performance electrolytes for large-scale devices. Imidazolium-based ILs are known to possess high ionic conductivities and moderate electrochemical stabilities. In this study, we report the physicochemical and electrochemical properties of K[FSA]–[C2C1im][FSA] (FSA = bis(fluorosulfonyl)amide; C2C1im = 1-ethyl-3-methylimidazolium) ILs as new electrolytes for KIBs. A phase diagram constructed from differential scanning calorimetry results indicates that the melting point of this IL is below 273 K at compositions of x(K[FSA]) = 0–0.20 (x(K[FSA]) = molar fraction of K[FSA]). The viscosity, ionic conductivity, and density of the IL were measured for x(K[FSA]) = 0–0.20. The ionic conductivity at x(K[FSA]) = 0.20 is 10.1 mS cm–1 at 298 K, which is comparable to that of typical organic solvent-based KIB electrolytes and higher than that of other ionic liquid electrolytes for KIBs. The electrochemical stability of M[FSA]–[C2C1im][FSA] (x(M[FSA]) = 0.20; M = K, Na, and Li) ILs was determined by cyclic voltammetry measurements. The K-based IL exhibits the widest electrochemical window of 5.19 V due to the negative redox potential of the K+/K couple. Thus, the K[FSA]–[C2C1im][FSA] ionic liquid is expected to be a highly conductive KIB electrolyte.

A distinguished class of hydrophobic ionic liquids bearing a Br<TEX>${\o}$</TEX>nsted acidic character derived from amide-like compounds were prepared by a neutralization reaction of N,N-diethylformamide, N,N-dibutylformamide, 1-formylpiperidine, and <TEX>$\varepsilon$</TEX>-caprolactam with trifluoroacetic acid and physical absorptions of <TEX>$CO_2$</TEX> in these ionic liquids were demonstrated and evaluated. <TEX>$CO_2$</TEX> solubilities in these ionic liquids were influenced by the molecular structure of the cation and were apparently increased with the molar volume. Comparison based on a volume unit reveals that <TEX>$CO_2$</TEX> solubilities in these liquids are relatively higher than those in imidazolium-based ionic liquids. Henry's coefficients calculated from low-pressure solubility tests at 313 to 333 K were used to derive the thermodynamics quantities. Enthalpy and entropy of solvation may share equal contributions in solubility.

Thiazolium-based ionic liquids: Synthesis, characterization and physicochemical properties

Selected physical and chemical properties and tribological data for a newly-developed, imidazolium-based ionic liquid (IL) are presented. The IL is soluble in the SAE 5W-30 oil up to a certain weight percentage, and is as a promising candidate for use in lubrication applications, either in its neat version or as an oil additive. Characterization of the IL included dynamic viscosity at different temperatures, corrosion effects on cast iron cylinder liners, and thermal stability analysis. The tribological performance was evaluated using a reciprocating ring-on-liner test arrangement. When used in neat version this IL demonstrated friction coefficient comparable to a fully formulated engine oil, and when used as an oil additive it produced less wear.

Experimental and molecular modeling studies are conducted to investigate the underlying mechanisms for the high solubility of CO2 in imidazolium-based ionic liquids. CO2 absorption isotherms at 10, 25, and 50 degrees C are reported for six different ionic liquids formed by pairing three different anions with two cations that differ only in the nature of the "acidic" site at the 2-position on the imidazolium ring. Molecular dynamics simulations of these two cations paired with hexafluorophosphate in the pure state and mixed with CO2 are also described. Both the experimental and the simulation results indicate that the anion has the greatest impact on the solubility of CO2. Experimentally, it is found that the bis(trifluoromethylsulfonyl)imide anion has the greatest affinity for CO2, while there is little difference in CO2 solubility between ionic liquids having the tetrafluoroborate or hexafluorophosphate anion. The simulations show strong organization of CO2 about hexafluorophosphate anions, but only small differences in CO2 structure about the different cations. This is consistent with the experimental finding that, for a given anion, there are only small differences in CO2 solubility for the two cations. Computed and measured densities, partial molar volumes, and thermal expansion coefficients are also reported.

Effect of anion and methylation on the interionic interactions and reactivity of 1-butyl-2,3-dimethyl imidazolium-based ionic liquids

A novel molecular structure-based model for prediction of CO2 equilibrium absorption in blended imidazolium-based ionic liquids

1-n-Alkylimidazoles are a class of tunable solvents with low volatility and low viscosities. Although imidazoles have been known for some time in the pharmaceutical industry, and as convenient precursors for synthesizing imidazolium-based ionic liquids (ILs), only recently have they been given consideration in some of the same solvent-based separations applications that ILs have been studied for, such as post-combustion CO2 capture and natural gas treating. “Sweetening”, the removal of CO2, H2S, and other “acid” gases from natural gas (CH4), is an existing industrial application where low volatility, low viscosity physical solvents are already applied successfully and economically at large scale. Physical solvents are also used for syngas cleanup and in the emerging application of pre-combustion CO2 capture. Given the similarities in physical properties between 1-n-alkylimidazoles, and physical solvents currently used in industrial gas treating, the 1-n-alkylimidazole class of solvents warrants further investigation. Solubilities of CO2 and CH4 in a series of 1-n-alkylimidazoles were measured under conditions relevant to the use of physical solvents for natural gas treating: ∼5 atm partial pressure of CO2 and temperatures of 30–75 °C. Solubilities of CO2 and CH4 were found to be strongly dependent on temperature, with the solubility of each gas in all solvents diminishing with increasing temperature, although CO2 exhibited a stronger temperature dependence than CH4. Ideal CO2/CH4 solubility selectivities were also more favorable at lower temperatures in 1-n-alkylimidazole solvents with shorter chain lengths. CO2 solubility decreased with increasing chain length, while CH4 solubility exhibited a maximum in 1-hexylimidazole. The solubility trends observed with temperature and chain length can be explained through calculation of solution enthalpies and solvent fractional free volume as approximated from van der Waals volumes as calculated via atomic contributions. Of the solvents examined, 1-methylimidazole displays the most favorable CO2 solubility and CO2/CH4 selectivity, and has the lowest viscosity. A comparison of 1-methylimidazole to commercially used solvents reveals similar physical properties and the potential for use in industrial gas processing. Imidazolium-based ILs are also compared, although they appear less favorable for use within established process schemes given their higher viscosities and reduced capacity for CO2.

Fluoride ion yield and absorption spectral analysis of irradiated imidazolium-based room-temperature ionic liquids

Synthesis and characterization of physicochemical properties of imidazolium-based ionic liquids and their application for simultaneous determination of sulfur compounds

Imidazolium-based ionic liquid–assisted processing of natural biopolymers containing amine/amide functionalities for sustainable fiber production

This paper reports the synthesis of iron oxide nanoparticles using a freshly-made or recycled 1-butyl-3-methylimidazolium bis(triflylmethylsulfonyl)imide ([BMIM][Tf2N]) ionic liquid (IL). Iron pentacarbonyl (Fe(CO)5), which dissolves in [BMIM][Tf2N], thermally decomposed and subsequently oxidized to form iron oxide nanoparticles. These nanoparticles separated out automatically from the imidazolium-based ionic liquid mixtures. Multiple additional runs were tested in making iron oxide nanoparticles using recycled ionic liquid. The iron oxide nanoparticles made were characterized with transmission electron microscopy (TEM), high resolution TEM (HR-TEM) and powder X-ray diffraction (PXRD). The structure and thermal stability of the IL was examined using Fourier transform infrared (FT-IR) spectroscopy and thermal gravimetric analysis (TGA). We found that iron oxide nanoparticles with a narrow size distribution could be obtained. The [BMIM][Tf2N] ionic liquid showed no degradation based on the TGA and FT-IR study. The solvent-recyclable process of making size-controlled nanoparticles should have a broad impact on the application of imidazolium-based ionic liquids in the synthesis of nanomaterials.