Single Ionic Liquid Research Articles

Dissolution of cellulose in imidazolium-based double salt ionic liquids

The dissolution of cellulose in double salt ionic liquids (DSILs) was studied in detail and compared with the dissolution in individual constituent ionic liquids (ILs). The DSILs, [C4mim](CH3CO2)xCl1-x (x is the mole fraction of the single component ILs), were synthesized using acetate and chloride salts of 1-butyl-3-methylimidazolium. These DSILs were then used for the investigation of the solubility of cellulose in the whole mole fraction range. Commercial cellulose (CC) powder, kraft pulp (KP), and prehydrolysis kraft pulp (PHKP) of jute were chosen as cellulose sources. The solubility of cellulose increased with an increasing temperature for [C4mim](CH3CO2)0.6Cl0.4 and with increasing amount of [C4mim]Cl in DSILs. The maximum solubility of CC powder was 32.8 wt% in [C4mim](CH3CO2)0.6Cl0.4 at 100 °C, while for KP and PHKP, solubilities were 30.1 and 30.5 wt%, respectively under the identical condition. Cellulose could be regenerated from the DSILs using water as an antisolvent. Structure, morphology, and thermal stability of the regenerated cellulosic materials were analyzed. DSILs could be recycled >99 % without a discernible change in structure. This work demonstrates that DSILs display enhanced solubility over ILs system and have potential as a chemical processing methodology.

A comprehensive method of ionic liquid screening and experimental verification for simultaneous separation of multiple sulfides from oil

Ionic liquid (IL) as the extractant has shown an excellent performance in oil desulfurization. However, it is still a great challenge to select an appropriate IL that can simultaneously remove multiple sulfides from oils due to enormous ILs' quantities. In this work, an ILs' screening method based on the fuzzy comprehensive evaluation function and COSMO-RS method was developed for oil extraction desulfurization. Four typical aromatic thiophene sulfides – thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) were considered as the removal targets, and n-heptane was chosen as the model oil. By this method, a single IL – 1-butyl-3-methylpyridinium dicyanamide ([BMPy][DCA]) was selected from 702 ILs for removing the four sulfides from n-heptane. Liquid-liquid equilibrium (LLE) data of n-heptane + TS/BT/DBT/4,6-DMDBT + [BMPy][DCA] systems at 298.15 K were measured and then correlated by the NRTL equation. A data processing method for LLE experimental indices, distribution coefficient and selectivity, was proposed for their crossed curves and different measuring ranges to facilitate the comparison of ILs' extraction performance. The comprehensive experimental indices based on this processing method were compared with the comprehensive predicted indices obtained by screening. The results showed a consistent trend between the two, and the excellent desulfurization performance of [BMPy][DCA] was confirmed. The separation mechanism was then analyzed through the quantum chemistry method. The results showed that the interactions of four sulfides with either n-heptane or [BMPy][DCA] both were the van der Waals interaction and steric effect. The [BMPy][DCA] could attract the sulfides more potently than the n-heptane, demonstrating the extraction's mechanism and characteristics. The stronger itself interactions of BT, DBT and 4,6-DMDBT as solid sulfides limited their solubility in liquid–liquid two phases. In addition, the decomposition of interaction energy showed that the attraction between the sulfides and the [BMPy][DCA] was dominated by dispersion, assisted by electrostatics, and equipped with a small amount of induction. The essence of repulsion between them was the exchange-repulsion.

Tailoring Phosphonium Ionic Liquids for a Liquid-Liquid Phase Transition.

The existence of more than one liquid state in a single-component system remains the most intriguing physical phenomenon. Herein, we explore the effect of cation self-assembly on ion dynamics in the vicinity of liquid-liquid and liquid-glass transition of tetraalkyl phosphonium ([Pmmm,n]+, m = 4, 6; n = 2-14) ionic liquids. We found that nonpolar local domains formed by 14-carbon alkyl chains are crucial in obtaining two supercooled states of different dynamics within a single ionic liquid. Although the nano-ordering, confirmed by Raman spectroscopy, still occurs for shorter alkyl chains (m = 6, n < 14), it does not bring calorimetric evidence of LLT. Instead, it results in peculiar behavior of ion dynamics near the liquid-glass transition and 20-times smaller size of the dynamic heterogeneity compared to imidazolium ionic liquids. These results represent a crucial step toward understanding the nature of the LLT phenomenon and offer insight into the design of efficient electrolytes based on ionic liquids revealing self-assembly behavior.

Dissolving microneedles based on ZnO nanoparticles and an ionic liquid as synergistic antibacterial agents.

The use of nanomaterials to replace antibiotics has developed rapidly in the past decade, among which zinc oxide nanoparticles (ZnO NPs) have been proven to exhibit antibacterial properties and low toxicity in the treatment of microbial infections, and have been applied in antibacterial agent preparation. However, one of the problems of ZnO NPs is that these particles do not disperse well in some media, which reduces their antibacterial effects. Ionic liquids (ILs) are a class of low melting point salts containing organic cations and organic/inorganic anions; they have good biocompatibility and can not only enhance the dispersion of ZnO NPs but also have antibacterial properties. Microneedles (MNs) are an emerging transdermal drug delivery platform, which can effectively establish a transport channel in the epidermis and deliver the drug to a predetermined depth without causing pain, skin damage or overstimulation. Dissolving microneedles (DMNs) have developed rapidly because of several advantages. In this study, it is verified that ZnO NPs dispersed in the imidazolidinyl IL exhibit excellent and enhanced antibacterial effects compared with single ZnO NPs and a single IL. Therefore, ZnO NPs/IL dispersion showed good antibacterial activity. Then, ZnO NPs/IL dispersions with synergistic antibacterial properties were used as antibacterial agents to prepare DMNs. In vitro antibacterial results showed that DMNs also had good antibacterial properties. Furthermore, DMNs were applied to treat wound infection. Antibacterial DMNs were inserted into the infected wound and then dissolved and released, resulting in microbial death and acceleration of wound healing.

Ionic Liquid Mixtures for Direct Air Capture: High CO2 Permeation Driven by Superior CO2 Absorption with Lower Absolute Enthalpy.

This paper reports a series of liquid materials suitable for use as high-performance separation membranes in direct air capture. Upon mixing two ionic liquids (ILs), namely N-(2-aminoethyl)ethanolamine-based IL ([AEEA][X]) and 1-ethyl-3-methylimidazolium acetate ([emim][AcO]), the resulting mixtures with a specific range of their composition showed higher CO2 absorption rates, larger CO2 solubilities, and lower absolute enthalpies of CO2 absorption compared to those of single ILs. NMR spectroscopy of the IL mixture after exposure to 13CO2 allowed elucidation of the chemisorbed species, wherein [AEEA][X] reacts with CO2 to form CO2-[AEEA]+ complexes stabilized by hydrogen bonding with acetate anions. Supported IL membranes composed of [AEEA][X]/[emim][AcO] mixtures were then fabricated, and the membrane with a suitable mixing ratio showed a CO2 permeability of 25,983 Barrer and a CO2/N2 selectivity of 10,059 at 313.2 K and an applied CO2 partial pressure of 40 Pa without water vapor. These values are higher than those reported for known facilitated transport membranes.

Structural organization of ionic liquids embedded in fluorinated polymers

• Hybrid materials based on ionic liquids (ILs) and PVDF were produced by solvent casting. • The structural organization of different ILs incorporated into PVDF were determined. • The morphology depends on the structural organization of ILs into the PVDF matrix. • A single IL polydispersion favors the ion-dipole interactions between the Il and PVDF matrix. Hybrid materials based on ionic liquids (ILs) and polymers are increasingly being used for the development of smart and multifunctional materials, allowing to tune polymer properties or introduce new ones. Nonetheless, the structural organization of ILs within the polymer matrix is not properly understood. This work reports on the structural organization of different ILs incorporated into polyvinylidene fluoride (PVDF) films. The effect of IL type ([Pmim][TFSI], [Pmpip][TFSI], [Bmim] 2 [NiCl 4 ] and [Bmim][FeCl 4 ]) incorporated into the PVDF matrix on the structural organization was evaluated and correlated to the observed variations in the morphological and physical-chemical properties. [Bmim][FeCl 4 ] and [Bmim] 2 [NiCl 4 ] leads to highly porous structures and the incorporation of ILs into the polymer matrix increases the electroactive β phase content of PVDF. Different structural organization of the hybrid materials at nanoscale has been found by small-angle neutron scattering experiments. Whereas just single polydisperse objects with average size of about 5 nm have been found in PVDF/[Pmim][TFSI] and PVDF/[Pmpip][TFSI] samples, more complex fractal-like organization of pores are present in PVDF/[Bmim][FeCl 4 ] and PVDF/[Bmim] 2 [NiCl 4 ]. Thus, IL type influences both the morphology and the electroactive phase of the polymer. Complex fractal-like organization observed for [Bmim][FeCl 4 ] and [Bmim] 2 [NiCl 4 ] into the PVDF matrix allows a porous morphology, while single polydispersed [Pmpip][TFSI] or [Pmpip][TFSI] into PVDF favors strong ion-dipole interactions between the IL and the polymer matrix, resulting in higher electroactive β phase contents.

Four-Component Heterocyclization Reaction for the One-Pot Synthesis of 2,4-Dichloro-Substituted Pyrano/Furo[2,3-d]pyrimidines in an Environmentally Benign Procedure Mediated by Ceric Ammonium Nitrate in Phosphorus Ionic Liquid

An unprecedented and efficient methodology for the synthesis of 2,4-dichloro-substituted pyrano[2,3-d]pyrimidines and 2,4-dichloro-substituted furo[2,3-d]-pyrimidines is conducted through the one-pot heterocyclization and four-component condensation of acetophenone derivatives, various aromatic aldehydes/potassium iodide, malononitrile, and carbon tetrachloride. The cerium(IV) ammonium nitrate (CAN) was used as a single electron oxidant and ionic liquid (HTPB) as a green promoter under mild conditions at ambient temperature for synthesizing pyrimidine derivatives in high yields. A possible radical mechanism is proposed for these transformations. CAN is found to play an essential role in each step of the reaction. The major advantages of this methodology are experimentally simplicity, environmentally benign, nontoxic, and inexpensive catalyst, excellent yields, and short reaction times.

Cation-fluorinated ionic liquids: Synthesis, physicochemical properties and comparison with non-fluorinated analogues

Series of homologues of cation-fluorinated ionic liquids (FILs) containing a perfluoro-octyl group attached to either an imidazolium or pyridinium cation and comprising iodide, bis(trifluoromethylsulfonyl)imide ([NTf2]¯), trifluoromethanesulfonate ([OTf]¯) or acetate ([OAc]¯) were prepared in excellent yield and purity. All ionic liquids were characterized by means of nuclear magnetic resonance and Fourier-transform infrared spectroscopies. Systematic studies of their physicochemical properties, including density, viscosity and refractive index were conducted over a range of temperatures, and compared with the non-fluorinated, alkyl-substituted counterparts (AILs). The results allow for the conclusion that the introduction of fluoroalkyl chains increases dispersion forces leading to a dislocation of [NTf2]¯ and [OTf]¯ towards the cation core, enforcing stronger hydrogen bond interactions of these anions with the cation than in ionic liquids with non-fluorinated alkyl chains. Additionally, structural rearrangements occur in the presence of fluoro-alkyl chain, leading to less efficient packing of acetate- and [OTf]¯-based AILs. This study hence provides the first experimental evidence for the occurance of nanosegregation and triphilicity in cation-fluorinated ionic liquids previously demonstrated through computational studies.A group contribution method was employed to show that the properties of FILs and AILs, such as density, can be predicted from their refractive index. An excellent correlation of predicted densities with experimentally obtained densities was obtained with R2 of 0.9628 for FILs. This study presents properties of single ionic liquids, which is the foundation for an extensive follow-up study on their binary mixture properties.

Molecular dynamics simulation of ionic liquid electrospray: Microscopic presentation of the effects of mixed ionic liquids

Micro-propulsion devices based on electrospray have advantages of high specific impulse, high precision and compact structure, and are able to meet the requirements of gravitational wave detection and other drag-free spacecrafts for micro-propulsion system. For electrospray thrusters, ionic liquid is the preferred propellant because of its low volatility, high electrical conductivity and thermal stability. Most of the studies presented today focus on single ionic liquid, while the properties of single ionic liquid are certain, which leads to a limitation of electrospray characteristics and hence propulsion performance. Mixing different kinds of ionic liquids broadens the properties of ionic liquids, and thus adjusts the characteristics of electrospray to meet the requirements of diversified space missions. In this paper, the effects of mixing two typical ionic liquids, 1-ethyltrimethylimidazole dicyanamide (EMIM-N(CN)2) and 1‑butyl‑trimethylimidazolium hexafluorophosphate (BMIM-PF6), on propellant properties and electrospray characteristics are investigated by molecular dynamics simulation and validated by comparing with experimental data. The result shows that the mixed ionic liquid changes the emission mode of electrospray thruster. Compared with BMIM-PF6, the specific impulse and thrust for the 50:50 (by mass) mixture increases by more than half of the difference between the two before mixing. In addition, the analysis shows that the range of extrusion voltage is widened by adjusting the mixing ratios to meet the mission requirements for certain specific impulse and thrust.

Ionogels Based on a Single Ionic Liquid for Electronic Nose Application.

Ionogel are versatile materials, as they present the electrical properties of ionic liquids and also dimensional stability, since they are trapped in a solid matrix, allowing application in electronic devices such as gas sensors and electronic noses. In this work, ionogels were designed to act as a sensitive layer for the detection of volatiles in a custom-made electronic nose. Ionogels composed of gelatin and a single imidazolium ionic liquid were doped with bare and functionalized iron oxide nanoparticles, producing ionogels with adjustable target selectivity. After exposing an array of four ionogels to 12 distinct volatile organic compounds, the collected signals were analyzed by principal component analysis (PCA) and by several supervised classification methods, in order to assess the ability of the electronic nose to distinguish different volatiles, which showed accuracy above 98%.

Highly efficient dye‐sensitized solar cells: A comparative study with two different system of solvent‐free binary room‐temperature ionic liquid‐based electrolytes

AbstractIn this work, novel redox electrolytes based on poly (ethylene oxide) (PEO) were prepared using binary ionic liquid 1‐methyl‐3‐propylimidazolium iodide (MPII) with 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) or 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4) to reduce the high viscosity of MPII. The addition of low viscosity ionic liquids is to overcome the low mass transportation of redox mediator faced by the single ionic liquid. Therefore, different ratios of ionic liquids were added, and their effect on the electrical properties of the ionic liquid‐based gel polymer electrolytes (GPE) was observed. It was confirmed that all the system dominant by ions rather than electron. The binary ionic liquid system containing 37.5 wt.% of BMIMBF4 showed the highest ionic conductivity of 24.2 mS cm−1. Fourier‐transform infrared and X‐ray diffraction studies confirmed that complexation occurred between all materials. The combination of two alkyl side chain length has enhanced the efficiency of the DSSC with short‐circuit current density (JSC) of 26.81 mA cm−1, open‐circuit voltage (VOC) of 0.67 V, fill factor of 44.5% and photovoltaic conversion efficiency (η) of 7.8%. This work has provided valuable insight for further stability of binary ionic liquid‐based GPE compared to single ionic liquid electrolytes.

Strengthened adsorption and corrosion inhibition of new single imidazole-type ionic liquid molecules to copper surface in sulfuric acid solution by molecular aggregation

This study proposes to use molecular aggregation method of organic ionic liquid molecules (OILMs) to intensify adsorption and corrosion inhibition to copper surface in sulfuric acid solution. Three new single imidazole-type OILMs including long carbon chain were synthesized, which were characterized by different methods such as nuclear magnetic resonance (NMR) and elemental analysis. The results suggest that the OILMs could process regular molecular assembly in sulfuric acid solution. The formed OILMs aggregates have been shown dependence on the OILMs concentrations and aggregation time. The chemistry adsorption of the OILMs aggregates on copper surface was demonstrated by various means including attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and spectroscopic ellipsometry and contacting angles, and atomic force microscopy (AFM) as well as scanning electron microscopy (SEM) imaging. Thus, the hydrophobic adsorption layers of the OILMs aggregates were yielded on copper surface. The electrochemistry survey suggests that the OILMs aggregates present nice corrosion resistance effect to copper in sulfuric acid solution (the maximal corrosion inhibition efficiency, >93%). The results were further understood by the theoretical simulation computation.

Isobaric vapor–liquid equilibrium for methyl acetate + methanol with double salt ionic liquid [EMIM][Cl]0.5[DCA]0.5 as entrainer at 101.3 kPa

The double salt ionic liquid (DSIL) [EMIM][Cl]0.5[DCA]0.5, which was made by mixing 1-ethyl-3-methylimidazolium chloride ([EMIM][Cl]) and 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]), was used for the separation of the methyl acetate + methanol azeotropic mixture. Isobaric vapor−liquid equilibrium (VLE) data for the ternary system of methyl acetate (1) + methanol (2) + [EMIM][Cl]0.5[DCA]0.5 (3) were measured at 101.3 kPa. The DSIL [EMIM][Cl]0.5[DCA]0.5 produced significant salting-out effect to methyl acetate and was able to break the azeotropic point of methyl acetate + methanol at low concentration of DSIL. The Non-Random Two-Liquid (NRTL) activity coefficient model was adopted to correlate the vapor−liquid equilibrium (VLE) data using three different objective functions, and the parameters of NRTL model were obtained based on the best objective function. Isobaric vapor−liquid equilibrium (VLE) data for the ternary systems of methyl acetate (1) + methanol (2) + [EMIM][Cl] (3) and methyl acetate (1) + methanol (2) + [EMIM][DCA] (3) were also measured at 101.3 kPa. The separation effects of DSIL [EMIM][Cl]0.5[DCA]0.5 were compared with the single ionic liquids [EMIM][Cl] and [EMIM][DCA].

Hydrogen Bonding Strength Determines Water Diffusivity in Polymer Ionogels.

Polymeric ionogels, cross-linked gels swollen by ionic liquids (ILs), are useful vehicles for the release and storage of molecular solutes in separation, delivery, and other applications. Although rapid solute diffusion is often critical for performance, it remains challenging to predict diffusivities across multidimensional composition spaces. Recently, we showed that water (a neutral solute) diffuses through alkyl-methylimidazolium halide ILs by hopping between hydrogen bonding sites on relatively immobile cations. Here, we expand on this activated hopping mechanism in two significant ways. First, we demonstrate that water diffuses through poly(ethylene glycol)diacrylate ionogels via the same mechanism at a reduced rate. Second, we hypothesize that the activation energy barrier can be determined from relatively simple 1H NMR chemical shift measurements of the proton responsible for H-bonding. This relationship enables water's diffusivity in ionogels of this class to be predicted quantitatively, requiring only (1) the composition-dependent diffusivity and Arrhenius behavior of a single IL and (2) 1H NMR spectra of the ionogels of interest. High-throughput microfluidic Fabry-Perot interferometry measurements verify prediction accuracy across a broad formulation space (four ILs, 0 ≤ xH2O ≤ 0.7, 0 ≤ ϕPEGDA ≤ 0.66). The predictive model may expedite IL-material screening; moreover, it intimates a powerful connection between solute mobility and hydrogen bonding and suggests targets for rational design.

Cation-Assisted Lithium-Ion Transport for High-Performance PEO-based Ternary Solid Polymer Electrolytes.

N‐alkyl‐N‐alkyl pyrrolidinium‐based ionic liquids (ILs) are promising candidates as non‐flammable plasticizers for lowering the operation temperature of poly(ethylene oxide) (PEO)‐based solid polymer electrolytes (SPEs), but they present limitations in terms of lithium‐ion transport, such as a much lower lithium transference number. Thus, a pyrrolidinium cation was prepared with an oligo(ethylene oxide) substituent with seven repeating units. We show, by a combination of experimental characterizations and simulations, that the cation's solvating properties allow faster lithium‐ion transport than alkyl‐substituted analogues when incorporated in SPEs. This proceeds not only by accelerating the conduction modes of PEO, but also by enabling new conduction modes linked to the solvation of lithium by a single IL cation. This, combined with favorable interfacial properties versus lithium metal, leads to significantly improved performance on lithium‐metal polymer batteries.

Cation‐Assisted Lithium‐Ion Transport for High‐Performance PEO‐based Ternary Solid Polymer Electrolytes

AbstractN‐alkyl‐N‐alkyl pyrrolidinium‐based ionic liquids (ILs) are promising candidates as non‐flammable plasticizers for lowering the operation temperature of poly(ethylene oxide) (PEO)‐based solid polymer electrolytes (SPEs), but they present limitations in terms of lithium‐ion transport, such as a much lower lithium transference number. Thus, a pyrrolidinium cation was prepared with an oligo(ethylene oxide) substituent with seven repeating units. We show, by a combination of experimental characterizations and simulations, that the cation's solvating properties allow faster lithium‐ion transport than alkyl‐substituted analogues when incorporated in SPEs. This proceeds not only by accelerating the conduction modes of PEO, but also by enabling new conduction modes linked to the solvation of lithium by a single IL cation. This, combined with favorable interfacial properties versus lithium metal, leads to significantly improved performance on lithium‐metal polymer batteries.

Probing the shear viscoelasticity of a nanoscale ionic liquid meniscus.

Ionic liquids (ILs) are emerging as novel solvents that exhibit peculiar mechanical properties in the form of thin films on metal surfaces under normal pressure. However, the mechanical properties of ILs in the form of nano-meniscus have not been analyzed yet. Here, we investigate the shear viscoelasticity of a single IL meniscus at the nanoscale. To characterize the shear rheological properties of ILs, we employ a quartz tuning fork-based atomic force microscope, conduct dynamic force spectroscopy, and analyse shear properties using the non-Newtonian-Maxwell model. The elastic response of the IL nanomeniscus is found to be about 25 times higher than that of the bulk IL bridge, whereas the viscous responses are similar. In addition, by conducting shear velocity-dependent measurements, we find that the IL meniscus shows nonlinear rheological behaviours. Interestingly, we observe that the relaxation time of the IL increases at a tip-substrate distance of about 60 nm.

Extraction of phenolic pollutants from industrial wastewater using a bulk ionic liquid membrane technique

ABSTRACT The academia and chemical industry are actively searching for alternative solvents to meet technology requirements since the most widely used solvents are harmful and volatile. For ionic liquids, there are several advantages over conventionally using organic membrane solvents, including high thermal stability, negligible vapour pressure, low volatility, etc. Here in this study, we have analyzed the abilities of ionic liquids as pure solvents as well as their binary mixtures, to recover phenolic compounds from the industrial wastewater. The field of phenol extraction from wastewater using ionic liquids remains less exposed, and we presume that the work of this kind would open up more and more opportunities for the scientific community as well as industrial people. Based on all these assumptions, the present work includes experimental data of a work which explains the possibilities of room temperature ionic liquids (RTILs) as potential bulk liquid membranes (BLM) for extracting phenol and other phenolic compounds from the industrial affluents. Four high hydrophobicity ionic liquids namely: 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [Bmim][NTf2], 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim] [PF6] and 1-ethyl-3-methyimidazolium bis(trifluoromethanesulfonyl) imide [Emim][NTf2] were used for investigating the Phenol extraction efficiency and stripping efficiency. To provide a best comprehension of the influence of the phenolic structure as well as the nature of cation on the extraction ability of the ILs, we tried to understand the molecular interactions between the phenolic compounds and the solvents. The influence of hydrophobicity of ionic liquids and different kinds of anions on the extraction of phenol and efficiencies of stripping were investigated. All the experimental investigations performed here indicated that the only cation part of the ionic liquid is not an important aspect directly in this extraction, but the hydrogen bonding and the solute-solvent interactions play a significant role in the phenol removal process from aqueous phase to IL phase. First, the optimal conditions of operating (settling time and stirring) were analyzed for the clarity of the experiments performed. Concentration of NaOH in enhancing the performance of ionic liquids was also inspected here in this study. A binary mixture of ionic liquids (BMILs) membrane was examined for the optimized parameters, and the efficiency of phenol extraction was analyzed with the efficiency obtained for the single ionic liquid (SIL) membranes. The phenol concentration was determined by UV/visible spectrophotometer absorbance measurements. The highest phenol extraction efficiencies of 91% and 98.5%, were achieved by using [Bmim][NTf2] and [Bmim][NTf2+PF6] respectively, and the higher stripping efficiencies came up with 79% and 84% respectively, for [Emim][NTf2] and [Bmim + Emim][NTf2]. The results show that the binary mixture ionic liquid (BMIL) membrane is a better choice than single ionic liquid (SIL) membrane solvents. Hence, [Bmim] [(NTf2+PF6)] is an excellent selection as it provides high phenol stripping and extraction efficiencies with a minimal solvent loss and better stability in transport process.

Potassium Single Cation Ionic Liquid Electrolyte for Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) are a promising post-lithium-ion battery (LIB), as their resources are abundant and low-cost and may have a higher voltage than LIBs. However, the high operating voltage and extremely high reactivity of potassium metal require a chemically safe electrolyte with oxidative and reductive stabilities. In this study, a potassium single cation ionic liquid (K-SCIL), which contains only K+ as the cationic species and has a high electrochemical stability, low flammability, and low vapor pressure, is developed as an electrolyte for PIBs. The mixture of potassium bis(fluorosulfonyl)amide and potassium (fluorosulfonyl)(trifluoromethylsulfonyl)amide at a molar ratio of 55:45 had the lowest melting point of 67 °C. The K+ concentration in this K-SCIL is high (8.5 mol dm-3 at 90 °C) due to the absence of solvents and bulky organic cations. In addition, the electrochemical window is as wide as 5.6 V, which enables the construction of PIBs with a high energy density. A high current density can be achieved with this K-SCIL, owing to the absence of a K+ concentration gradient. The electrolyte was successfully used with a graphite negative electrode, enabling the reversible intercalation/deintercalation of K+, as confirmed by X-ray diffraction.

QSPR Modeling of Liquid-liquid Equilibria in Two-phase Systems of Water and Ionic Liquid.

The increasing application of new ionic liquids (IL) creates the need of liquid-liquid equilibria data for both miscible and quasi-immiscible systems. In this study, equilibrium concentrations at different temperatures for ionic liquid+water two-phase systems were modeled using a Quantitative-Structure-Property Relationship (QSPR) method. Data on equilibrium concentrations were taken from the ILThermo Ionic Liquids database, curated and used to make models that predict the weight fraction of water in ionic liquid rich phase and ionic liquid in the aqueous phase as two separate properties. The major modeling challenge stems from the fact that each single IL is characterized by several data points, since equilibrium concentrations are temperature dependent. Thus, new approaches for the detection of potential data point outliers, testing set selection, and quality prediction have been developed. Training set comprised equilibrium concentration data for 67 and 68 ILs in case of water in IL and IL in water modeling, respectively. SiRMS, MOLMAPS, Rcdk and Chemaxon descriptors were used to build Random Forest models for both properties. Models were subjected to the Y-scrambling test for robustness assessment. The best models have also been validated using an external test set that is not part of the ILThermo database. A two-phase equilibrium diagram for one of the external test set IL is presented for better visualization of the results and potential derivation of tie lines.