Anion Of Ionic Liquid Research Articles

A new approach for the use of cellulose-rich solids from biorefinery in the formulation of gel-like materials

The increase in environmental problems and the necessity of substituting fossil fuels in the production of materials is increasing the demand for a new type of raw materials and formulation methods. This study used a cellulose-rich solid (CRS) from a biorefinery process to formulate gel-type materials, ionogels, and hydrogels. A phosphate anion ionic liquid, [Emim][DEP], was used to dissolve the CRS and formulate the ionogels. Hydrogels were formulated by submerging the ionogels in water until the ionic liquid was completely removed. Commercial microcrystalline cellulose (Avicel) was used as a reference. Comparing Avicel and CRS gels, it was discovered that the CRS gives higher rheological properties to the materials. In both cases, due to the utilization of a phosphate anion ionic liquid, cellulose phosphorylation gave these materials important properties such as higher bioactivity, flame retardant, or better absorption capacities. On the other hand, the rheological properties for CRS ionogels and hydrogels are double that of Avicel, with values ranging between 103 and 104 Pa, mainly due to the presence of lignin acting as a reinforcement. It was also observed by SEM that this lignin does not affect the internal structure and morphology of the gels. This work successfully demonstrated that a new raw material, a cellulose-rich solid from biorefinery, could be a good substitute for commercial cellulose in the formulation of ionogels and hydrogels for their use in biomedical and energy fields.

Extraction of lithium ions from salt lake brine using magnetic ionic liquid: Kinetic and equilibrium studies

In this study, 1-hexyl-3-methylimidazolium [C6mim+] as cation and bis(trifluoromethylsulfonyl)imide [NTf2-] as anion of ionic liquid (ILs) using the neutral tributyl phosphate (TBP) and magnetic ionic liquid (MNP@ILs) were developed for efficient extraction of lithium ions (Li+) from Salt Lake Brine. The synthesized MNPs@ILs adsorbent was characterized using Fourier transform infrared spectroscopy, vibrating sample magnetometer, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The effective parameters on lithium ions extraction process were studied including solution pH (∼7), adsorbent dosage (100 & 300 mg) and extraction time (30 & 120 min). The extraction efficiency of lithium ion was 94%, 78% for ILs and MNP@ILs under the optimal conditions. The adsorption rate, adsorption capacity and mechanism are examined with applying the kinetic, isotherm and free energy models on experimental data, respectively. The Langmuir isotherm proposed adsorption capacity of 62.5 mg/g and 20.8 mg/g for ILs and MNPs@ILs, respectively. This indicated a monolayer adsorption pattern for lithium ions over MNPs@ILs and multilayer pattern over ILs. The free energy model is suggested a physical sorption mechanism for lithium ions. The obtained results are performed the green ILs and novel MNPs@ILs can be used as an alternative extractant for Li+ from Salt Lake Brine.

Understanding the effects of ionic liquids and antisolvent addition on the extraction and recovery of Pinus radiata bark components

Ionic liquids (ILs) are being increasingly explored as extraction solvents due to their tunable properties, which can control their ability to dissolve an array of solutes. IL selection requires an in-depth understanding of the consequences of IL structure on extraction outcomes for different substrates. Here, 14 ILs containing cations and anions that have been systematically modified to examine key structural effects have been explored for the extraction of chemical components from Pinus radiata bark. The extraction efficiency relative to the mass of bark ranged from 4 to 70%, and the isolation of bark components was evaluated using antisolvent addition. Extraction outcomes highlighted the importance of the IL anion in affecting extraction efficiency and selectivity, with a secondary role from the IL cation, and point toward a simple route for improving the overall selectivity of biomass extractions through control of the antisolvent addition process.

Modifying the Electrocatalytic Selectivity of Oxidation Reactions with Ionic Liquids.

The “solid catalyst with ionic liquid layer” (SCILL) is an extremely successful new concept in heterogeneous catalysis. The idea is to boost the selectivity of a catalyst by its modification with an ionic liquid (IL). Here, we show that it is possible to use the same concept in electrocatalysis for the selective transformation of organic compounds. We scrutinize the electrooxidation of 2,3‐butanediol, a reaction which yields two products, singly oxidized acetoin and doubly oxidized diacetyl. When adding the IL (1‐ethyl‐3‐methyl‐imidazolium trifluormethanesulfonate, [C2C1Im][OTf]), the selectivity for acetoin increases drastically. By in situ spectroscopy, we analyze the underlying mechanism: Specific adsorption of the IL anions suppresses the activation of water for the second oxidation step and, thus, enhances the selectivity for acetoin. Our study demonstrates the great potential of this approach for selective transformation of organic compounds.

Fluorination effect on the solubility of C60 in a bis(trifluoromethylsulfonyl)imide based ionic liquid

Highly fluorinated fullerenes with a chemical composition of C60F48 have been prepared and characterized. Their solubility of the new nanomaterials in the ionic liquid (IL) has been compared with raw fullerenes C60. Fluorination may appear as a convenient method to enhance the solubility of carbonaceous nanomaterials in a fluorinated based anion IL. Indeed, the ability of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BmIm][NTf2]), to solubilize C60 and C60F48 was investigated using optical microscopy and UV–vis spectroscopy. While C60 has very poor solubility in this IL (below 0.07 mmol/L), the solubility increases at least eightfold, i.e. more than 1.0 mg/mL (or 0.61 mmol/L) for C60F48 samples. The presence of fluorine atoms on fullerene seems to enhance the stability of the solvated molecules in IL thanks to the limitation of the aggregation of C60F48 in [BmIm][NTf2]. This improvement of the solubility could be explained by the beneficial effect of the fluorination that induces a decrease of the π-π interaction between carbonaceous solutes as the carbon hybridization changes from sp2 to sp3 through the formation of C-F covalent bonds and thus enhances the interaction between the solvent and the solute. Fluorination appears as an efficient approach to limit the use of volatile organic compounds usually used as co-solvent to enhance the dispersion mechanism.

Structure, dynamics and ionic conductivities of ternary ionic liquid/lithium salt/DMSO mixtures

In this paper we report classical Molecular Dynamics and ab initio Density Functional Theory simulations of the structure and single particle dynamics of ternary mixtures of a protic (ethylammonium nitrate, EAN) and an aprotic (1-Ethyl-3-methylimidazolium tetrafluoroborate, EMIMBF4) ionic liquid, lithium salts with common anion and a molecular cosolvent, dimethyl sulfoxide (DMSO). The coordination numbers and electrical conductivities of the different mixtures have been calculated throughout the whole concentration range, and the differences between mixtures with the protic and aprotic ionic liquids were analyzed. In both cases, the evolution of the electrical conductivity is seen to correlate well with the formation of mixed tetrahedral solvation complexes of lithium cations with ionic liquid anions and cosolvent molecules. The differences in the solvation and charge transport mechanisms in hydrogen bonded mixtures and those based in the aprotic ionic liquid are analyzed. Our conclusions indicate that the major feature behind the electrical conductivity of the ternary mixtures is the composition of the solvation shell of the metal cations in the mixtures and the rate at which anions in it are replaced by DMSO molecules.

Halide anions engineered ionic liquids passivation layer for highly stable inverted perovskite solar cells

Long-term stability remains a great challenge for metal halide perovskite solar cells (PSCs). The utilization of ionic liquids (ILs) is a promising strategy to solve the stability problem. However, few studies have focused on controlling the halide anions of ILs, in which different organic cations can modulate the melting point of ILs and film crystal growth. Here, ILs with a 1-ethyl-3-methylimidazolium (EMIM+) cation and different halide anions (X = Cl, Br, and I) are employed in inverted PSCs. The results show that EMIMX can form a 1D passivation layer by the in situ growth technique and influence the surface morphology of the perovskite film. These EMIMX-treated layers simultaneously suppress the surface defects and nonradiative energy losses and improve the hydrophobic properties. As a result, a power conversion efficiency (PCE) of 20.0% is obtained for the EMIMBr-modified PSCs compared to 18.06% for the control device. Moreover, the unencapsulated devices maintain more than 90% of their initial PCE over 3000 h under ambient air, which is among the best long-term stabilities reported for NiOx-based inverted PSCs. It also retains 74.2% and 49.5% of the initial PCE value after aging under harsher conditions, such as an 85 ± 5% relative humidity (RH) environment and at 85 °C for 48 h, respectively.

Aqueous-nonaqueous solvent-switching ion chromatography of halide impurities in ionic liquids

We here propose an efficient solvent-switching preconcentration method for the ion-chromatographic (IC) determination of halide impurities contained ionic liquids (ILs). Because halide impurities strongly affect the physicochemical properties of ILs, their analysis is an important task for the successful utilization of ILs. Although IC is an efficient method for this purpose, its application still involves significant challenges. The major halide impurities, such as F− and Cl−, show much smaller retention in aqueous anion-exchange chromatography than IL component anions. Therefore, if an IL sample is directly analyzed by IC with aqueous mobile phases, the halide impurities are eluted earlier, whereas the IL component anion is hardly eluted and gives a large peak once eluted. Thus, the introduction of the IL component anions into the IC separation column should be avoided for efficient analyses and also for preventing the degradation of the column by the accumulation of the IL anions in it. This problem, which arises from the ion-exchange selectivity in aqueous media, is solved by a solvent switching preconcentration method. The anion-exchange selectivity in aqueous media is reversed by a use of an aprotic solvent, such as acetonitrile (MeCN). Hence, we have come up with the idea of preconcentrating anions in MeCN and stripping them with an aqueous mobile phase for IC analysis. The introduction of the IL component anions into the IC separation column is substantially reduced while maintaining high sensitivity for the halide impurities. Sub μM impurities are detectable in the mM level of ILs.

Thermodynamic study of binary mixtures of 2-propanol with ionic liquids, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexylammonium bis(trifluoromethylsulfonyl)imide

In this work, densities, speeds of sound, refractive indices and viscosities of three binary mixtures containing the ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate and triethylhexyl-ammonium bis(trifluoromethylsulfonyl)imide, mixed with 2-propanol at wide temperature and composition ranges at atmospheric pressure have been measured. From these experimental data, the excess molar volume, excess molar compressibility, deviation in refractive index and deviation in viscosity have been calculated. Excess properties have been correlated with the composition data using Redlich-Kister polynomial equation. The effects of temperature, cation and anion of ionic liquid on the physicochemical properties were analysed and discussed in terms of intermolecular interactions occurring in the studied systems. The Prigogine-Flory-Patterson theory was examined for suitability for the correlation of excess molar volumes with compositions.

Liquid-Liquid Extraction of the Eu(III) Cation by BTP Ligands into Ionic Liquids: Interfacial Features and Extraction Mechanisms Investigated by MD Simulations.

What happens at the ionic-liquid (IL)/water interface when the Eu3+ cation is complexed and extracted by bis(dimethyltriazinyl) pyridine "BTP" ligands has been investigated by molecular dynamics and potential of mean force simulations on the interface crossing by key species: neutral BTP, its protonated BTPH+ form, Eu3+, and the Eu(BTP)33+ complex. At both the [BMI][Tf2N]/water and [OMI][Tf2N]/water interfaces, neither BTP nor Eu(BTP)33+ are found to adsorb. The distribution of Eu(BTP)23+ and Eu(BTP)3+ precursors of Eu(BTP)33+, and of their nitrate adducts, implies the occurrence of a stepwise complexation process in the interfacial domain, however. The analysis of the ionic content of the bulk phases and of their interface before and after extraction highlights the role of charge buffering by interfacial IL cations and anions, by different amounts depending on the IL. Comparison of ILs with octanol as the oil phase reveals striking differences regarding the extraction efficiency, the affinity of Eu(BTP)33+ for the interface, the effects of added nitric acid and of counterions (NO3- vs Tf2N-), charge neutralization mechanisms, and the extent of "oil" heterogeneity. Extraction into octanol is suggested to proceed via adsorption at the surface of water pools, nanoemulsions, or droplets, with marked counterion effects.

Confined ionic liquids in covalent organic frameworks toward the rational design of high-safety lithium metal battery

To solve the serious safety issues such as highly flammable organic electrolyte, this work developed a novel lithium metal battery containing quasi-solid-state electrolyte (QSSE) with ionic liquid (ILs)/Li salt as electrolyte and covalent organic frameworks (COFs) as hosts. The micro-scale structure and dynamics properties of several ILs confined in COFs were investigated in detail using molecular dynamics (MD) simulations. It is found that the distinctly alternate layering structure of cations and anions of ILs from the pore surface to pore center are formed inside COFs due to the strong interaction between cations/anions and pore wall of COFs. The orientational preferences of confined ILs are observed depending on the size of anions. Inside the larger pores of COFs, the bulk-like structure of confined ILs is found, which tends to enlarge the leakage risk of electrolytes, while the smaller pore size of COFs can reduce the diffusion of ILs and further limit the ionic conductivity of electrolytes. The prepared QSSE with the appropriate-size ILs confined in medium pore-size COFs shows a higher ionic conductivity (0.87 mS cm−1 at 30 °C), more efficient inhibition of lithium dendrite (above 2000 h stability) and better battery performance (150.4 mAh g−1 at 0.1C). These findings from both simulations and experiments confirm the potential of COFs for achieving nondendritic lithium growth in lithium metal batteries.

A density functional theory study on the water aggregation behaviour of fatty acid-based anionic surface active ionic liquids

The hydrogen bond interactions between methyl-imidazolium cation (MIM+) and fatty acid anions (CmHnCOO–, where m = 1–6; n-3–13) of ionic liquids are studied in both gas phase and water phase using density functional theory. The structural properties show that the presence of N–H···O and C–H···O hydrogen bonds between [MIM]+ and [CmHnCOO]– (m = 1–6; n-3–13) ionic liquids. From the vibrational frequency analysis, it was found that the hydrogen bond interaction between [MIM]+ and [CmHnCOO]– (m = 1–6; n-3–13) ionic liquids are red-shifted in frequency. The natural bond orbital analysis show that the N–H···O hydrogen bond associated with the large charge transfer which has the higher stabilization energy (i.e. E(2) ~ 38 kcal/mol). Further, the cation/anion–water cluster (H2O)1–3 interactions show that the water molecules are preferred to interact with anions. In the case of ionic liquid–water cluster interaction, the water molecules occupies the interstitial space between cation and anion of ionic liquids which results in weakening the cation–anion interaction.

An ionic liquid-based ratio fluorescent sensor for real-time visual monitoring of trace Hg2+

As a brand probe material, functional ionic liquids (ILs) have already been successfully employed in the detections of many targets, however, few of them focused on the real-time visual monitoring of trace Hg2+, one of the most representative heavy metal ions. Herein, we report a novel ratio fluorescent sensor using facile mixture of [RDB] [P66614] IL and 7-hydroxycoumarin (HDC) for the on-site monitoring of Hg2+ ignoring background interferences. To utilize and enhance the affinity characteristics of rhodamine B for Hg2+, it was first covalently linked onto the anion of IL and further mixed with HDC to construct a novel ratio fluorescent sensor for the achievement of self-calibration. Furthermore, this novel sensor showed a rapid and obvious color rendering performance from light white to opera pink even towards trace mercury(Ⅱ) in the range of 0.1–50 nM and could be further used even in common real samples such as waste water, urine, human plasma et. al. Most importantly, the sensor could be assembled into a paper sensor for the on-site visual monitoring of trace Hg2+ ranging from 10 to 400 nM only taking 2 s, which enable to meet requirements for mercury(Ⅱ) limitations of WHO (30 nM) and EPA (10 nM).

Aqueous Biphasic Systems Comprising Natural Organic Acid-Derived Ionic Liquids

Despite the progress achieved by aqueous biphasic systems (ABSs) comprising ionic liquids (ILs) in extracting valuable proteins, the quest for bio-based and protein-friendly ILs continues. To address this need, this work uses natural organic acids as precursors in the synthesis of four ILs, namely tetrabutylammonium formate ([N4444][HCOO]), tetrabutylammonium acetate ([N4444][CH3COO]), tetrabutylphosphonium formate ([P4444][HCOO]), and tetrabutylphosphonium acetate ([P4444][CH3COO]). It is shown that ABSs can be prepared using all four organic acid-derived ILs paired with the salts potassium phosphate dibasic (K2HPO4) and tripotassium citrate (C6H5K3O7). According to the ABSs phase diagrams, [P4444]-based ILs outperform their ammonium congeners in their ability to undergo liquid–liquid demixing in the presence of salts due to their lower hydrogen-bond acidity. However, deviations to the Hofmeister series were detected in the salts’ effect, which may be related to the high charge density of the studied IL anions. As a proof of concept for their extraction potential, these ABSs were evaluated in extracting human transferrin, allowing extraction efficiencies of 100% and recovery yields ranging between 86 and 100%. To further disclose the molecular-level mechanisms behind the extraction of human transferrin, molecular docking studies were performed. Overall, the salting-out exerted by the salt is the main mechanism responsible for the complete extraction of human transferrin toward the IL-rich phase, whereas the recovery yield and protein-friendly nature of these systems depend on specific “IL-transferrin” interactions.

Theoretical Mechanism on the Cellulose Regeneration from a Cellulose/EmimOAc Mixture in Anti-Solvents.

The experiments on cellulose dissolution/regeneration have made some achievements to some extent, but the mechanism of cellulose regeneration in ionic liquids (ILs) and anti-solvent mixtures remains elusive. In this work, the cellulose regeneration mechanism in different anti-solvents, and at different temperatures and concentrations, has been studied with molecular dynamics (MD) simulations. The IL considered is 1-ethyl-3-methylimidazolium acetate (EmimOAc). In addition, to investigate the microcosmic effects of ILs and anti-solvents, EmimOAc-nH2O (n = 0–6) clusters have been optimized by Density Functional Theory (DFT) calculations. It can be found that water is beneficial to the regeneration of cellulose due to its strong polarity. The interactions between ILs and cellulose will become strong with the increase in temperature. The H-bonds of cellulose chains would increase with the rising concentrations of anti-solvents. The interaction energies between cellulose and the anions of ILs are stronger than that of cations. Furthermore, the anti-solvents possess a strong affinity for ILs, cation–anion pairs are dissociated to form H-bonds with anti-solvents, and the H-bonds between cellulose and ILs are destroyed to promote cellulose regeneration.

Design and Characterization of Aprotic N-Heterocyclic Anion Ionic Liquids for Carbon Capture

Design and Characterization of Aprotic <i>N</i>-Heterocyclic Anion Ionic Liquids for Carbon Capture

Intermolecular and Intramolecular Friedel‐Crafts Acylation of Carboxylic Acids using Binary Ionic Liquids: An Experimental and Computational Study

AbstractTraditional Friedel‐Crafts acylation with acid halides suffers from waste byproducts such as SO2, HCl, and the hydrolysis of Lewis acid catalyst. Thus, the environmentally benign intermolecular and intramolecular Friedel‐Crafts acylation of arenes with carboxylic acids as acylating agents has been investigated using a mixture of deep eutectic solvent and an ionic liquid as reaction media under microwave irradiation. The Friedel‐Crafts acylations with carboxylic acids as acylating agents are challenging due to the low reactivity of carboxylic acids. In this paper, the desired products were obtained at moderate to good yields under microwave irradiation for a short reaction time. The Friedel‐Crafts cyclization of 4‐phenylbutyric acid is more effective than 3‐phenylpropionoic acid under the present method. The reaction mechanism is proposed by combining experiments with density functional theory calculations, highlighting the critical role of ZnCl2, triflate anion (CF3COO−) in binary ionic liquids, and acidic conditions in accomodating a kinetic accessible pathway making the C−C bond.

Ionic liquids design for efficient separation of anthracene and carbazole

• COSMO-RS is applied to screen ionic liquids for separation of anthracene and carbazole. • The anthracene with high purity can be obtained by ionic liquids. • The anthracene and carbazole do not form solid solutions in Ionic liquids. • The separation mechanism of anthracene and carbazole in Ionic liquids is discussed. Anthracene (ANT) and carbazole (CAR) are highly value-added compounds in chemical industry. They are always mixed in preliminary processing products of high temperature coal tar and need to be separated and purified. In this study, ionic liquids (ILs) were used to separate ANT and CAR. [C 3 PY], [PM 2 IM] and [PMPIP] cations along with 7 classes of anions were screened by the conductor-like screening model for real solvents (COSMO-RS). [PMPIP][TFAc] (IL a ) and [PMPIP][Ac] (IL b ) were selected and synthesized. The structures of ILs were studied by σ-profile at the micro-level to analysis the hydrogen bonds formed between anion of ILs and H-N of CAR. The ternary phase diagrams of ANT-CAR-ILs were plotted to analysis the separation efficiency. Two ILs were used as extractant to separate ANT and CAR. The separation results showed that the synthesized ILs were the highly efficient solvents. The purity of refined ANT separated by IL b was improved to 97.87 wt%, with a yield of 80.04 wt%. The separation mechanism of ANT and CAR was further discussed.

Influencing the froth flotation of LiAlO2 and melilite solid solution with ionic liquids.

In the present work experiments for single mineral flotation against LiAlO2 and melilite s.s. were carried out for seven ionic liquids (ILs). From these, IL-1 with an imidazolium cation and a bromide anion and IL-7 with a pyridinium cation and a bromide anion were selected for further flotation experiments (dosage, pH). Flotation experiments were also conducted using naphthenic acid, a conventional flotation fatty acid-based collector, and FS-2, a commercial collector in order to compare the results with ILs. Moreover, the effects of different anions in the ILs on the flotation were evaluated and a significant influence on the hardness of anions was found on the flotation process. Finally, a pre-functionalization was also explored with modified cholesterol derivatives, comparing the effect of cholesterylsulfate and cholesterylphosphate on the flotation of LiAlO2 and melilite s.s. This study is vital for the further optimization of lithium recovery from the pyrometallurgical recycling path of lithium-ion batteries and the flotation of primary minerals such as aluminosilicates.

Synergistic Effect of Ionic Liquid (Il) Cation and Anion Inhibits Negative Difference Effect on Mg in Water - Il Mixtures

Synergistic Effect of Ionic Liquid (Il) Cation and Anion Inhibits Negative Difference Effect on Mg in Water - Il Mixtures