Suitable Ionic Liquids Research Articles

MW irradiation and ionic liquids as green tools in hydrolyses and alcoholyses

Abstract The optimized HCl-catalyzed hydrolysis of alkyl diphenylphosphinates is described. The reaction times and pseudo-first-order rate constants suggested the iPr > Me > Et ∼ Pr ∼ Bu order of reactivity in respect of the alkyl group of the phosphinates. The MW-assisted p-toluenesulfonic acid (PTSA)-catalyzed variation means a better alternative possibility due to the shorter reaction times, and the alkaline hydrolysis is another option. The transesterification of alkyl diphenylphosphinates took place only in the presence of suitable ionic liquids, such as butyl-methylimidazolium hexafluorophosphorate ([bmim][PF6]) and butyl-methylimidazolium tetrafluoroborate ([bmim][BF4]). The application of ethyl-methylimidazolium hydrosulfate ([emim][HSO4]) and butyl-methylimidazolium chloride ([bmim][Cl]) was not too efficient, as the formation of the ester was accompanied by the fission of the O–C bond resulting in the formation of Ph2P(O)OH. This surprising transformation may be utilized in the phosphinate → phosphinic acid conversion.

Solvation of potential stable cations and anions originating from the Martian regolith in select ionic liquids

Element recovery from the Martian regolith using ionic liquids (ILs) is an active area of research within the field of in-situ resource utilization. In this work, we performed a classical molecular dynamics (MD) simulation study to better understand the solvation thermodynamics and structures of potential cationic and anionic species originating from the Martian regolith in two select ILs, i.e., 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) and 1-ethyl-3-methylimidazolium hydrogen sulfate ([emim][HSO4]), at two temperatures of 298.15 and 473.15 K. The studied cationic and anionic species represent the stable ions, i.e., a series of tetra-, tri-, di-, and monovalent cations, as well as several silicate, phosphate, chromate, titanate, and select halide anions, based on the mineral composition of the Martian regolith. We calculated the solvation free energies (SFEs) of these ionic species in the ILs using the free energy perturbation method. Moreover, we investigated the solvation environment of these ionic solutes by generating the relevant radial distribution functions and calculating the running coordination numbers of ILs' anions and cations surrounding the solutes. Overall, the average absolute values of the SFEs for cationic solutes increase with increasing ion valency (charge) and size of the solute at both temperatures. For anionic solutes, a more complex effect of anion molecular size and charge is responsible for the trends observed in the absolute values of the SFEs. For example, we found orthosilicate to be the most soluble anionic species in both ILs. On the other hand, the dichromate anion was found to be essentially insoluble in both ILs. Comparing between the solvation efficiencies of the ILs, [emim][Ac] shows larger negative SFE values than [emim][HSO4] for all cationic solutes at both temperatures. While the temperature effect on the solvation of cationic solutes is mixed, higher temperatures generally favor the dissolution of the anionic solutes in both ILs. Our results provide molecular insights into the solvation thermodynamics of various potential ionic species that may be extracted from the Martian regolith using suitable ILs.

Prediction of Potential Ionic Liquids (ILs) for the Solid-Liquid Extraction of Docosahexaenoic Acid (DHA) from Microalgae Using COSMO-RS Screening Model.

This study performs a screening of potential Ionic Liquids (ILs) for the extraction of Docosahexaenoic Acid (DHA) compounds by the calculation of capacity values. For this purpose, a Conductor-Like Screening Model for Real Solvents (COSMO-RS) was employed to study the molecular structures of the ILs, and therefore, predict their extraction potential. The capacity values of 22 anions combined with 16 cations based ILs, were investigated to evaluate the effectiveness of ILs in the extraction of DHA. It was found that among the investigated ILs, a combination of tetramethyl ammonium with SO4 or Cl was the best fit for DHA extraction, followed by pyrrolidinium, imidazolium, pyridinium and piperidinium. Furthermore, it was observed that the extraction capacity and the selectivity of ILs decreased with an increase in alkyl chain length; therefore, ethyl chain-ILs, with the shortest chain lengths, were found to be most suitable for DHA extraction. The predicted results were validated through the experimentally calculated extraction yield of a DHA compound from Nannochloropsis sp. Microalgae. Five selected ILs, namely [EMIM][Cl], [BMIM][Cl], [TMAm][Cl], [EMPyr][Br] and [EMPyrro][Br], were selected from COSMO-RS for empirical extraction purposes, and the validation results pinpointed the good prediction capabilities of COSMO-RS. The findings in this study can simplify the process of selecting suitable ILs for DHA extraction and reduce the number of required empirical evaluations.

Experimental investigation of ionic liquids as substitute for lithium bromide in water absorption chillers

Ionic liquids (ILs) have been proposed as alternative absorbents for absorption chillers, e.g. to cope with crystallization. Since there is a huge amount of different ILs available, it seems to be convenient to choose a suitable IL for an absorption chiller not by experimental trials but rather by theoretical modeling. However, the model’s results must be validated with experimental data to evaluate their prediction quality. In the paper at hand the performance of three different ILs ([Choline][OAc], [emim][Cl], [mmim][EtCO2]) and lithium bromide is compared experimentally in a fully operable absorption chiller with water as the refrigerant. The cooling capacity, the coefficient of performance, the specific circulation ratio of the chiller and the heat transfer capability of the absorber are determined. When using LiBr, the highest cooling capacity is achieved, and the highest heat transfer coefficients and presumably the least mass transfer resistance are present. The experimental data show that equilibrium state simulations will lead to completely erroneous results. Neither LiBr nor the ILs come close to their equilibrium state and differences amongst the investigated absorbents are huge. It furthermore seems almost impossible to choose suitable ILs for absorption chillers by investigating isolated physical properties.

Molecular simulation on the stability and adsorption properties of choline-based ionic liquids/IRMOF-1 hybrid composite for selective H2S/CO2 capture

The compatibility and performance of an Isoreticular Metal-Organic Frameworks (IRMOF-1) impregnated with choline-based ionic liquids (ILs) for selective adsorption of H2S/CO2, were studied by molecular dynamics (MD) simulation. Cholinium alanate ([Chl][Ala]) was nominated as the suitable IL for impregnation into IRMOF-1, consistent with the low RMSD values (0.546 nm, 0.670 nm, 0.776 nm) at three IL/IRMOF-1 w/w ratios (WIL/IRMOF-1 = 0.4, 0.8, and 1.2). The [Chl]+ and [Ala]− ion pair was located preferentially around the carboxylate group within the IRMOF-1 framework, with the latter interacting strongly with the host than the [Chl]+. Results of radius of gyration (Rg) and root mean square displacement (RMSD) revealed that a ratio of 0.4 w/w of IL/IRMOF-1 (Rg = 1.405 nm; RMSD = 0.546 nm) gave the best conformation to afford an exceptionally stable IL/IRMOF-1 composite. It was discovered that the IL/IRMOF-1 composite was more effective in capturing H2S and CO2 compared to pristine IRMOF-1. The gases adsorbed in higher quantities in the IL/IRMOF-1 composite phase compared to the bulk phase, with a preferential adsorption for H2S, as shown by the uppermost values of adsorption (AH2S = 17.954 mol L−1 bar-1) and an adsorption selectivity (ASH2S/CO2 = 43.159) at 35 IL loading.

3D-Printable Ionogels Based on Protic Ionic Liquids for Energy Applications

In light of the well-known challenges regarding the global energy economy and climate issues fuel cells are widely discussed for their benefits and potential applications in the future. One of the main problems of PEM-fuel cells is that Nafion®-membranes have a limited application temperature window of ≤ 80 °C at ambient pressure due to dehydration and corresponding loss of conductivity at higher temperatures. [1] As a result there is a significant need for new membranes of a precise and defined size and geometry exhibiting significant ion mobilities far above 100 °C.Based on their highly useful properties like thermal stability, non-flammability, and high ionic conductivities ionic liquids (ILs) are promising components in energy devices such as batteries, solar cells or fuel cells. For proper function of, for example, fuel cell membranes, it is, however, necessary to immobilize the ILs in a polymer matrix, resulting in ionogels (IGs) combining the characteristics of the respective IL with e. g. the mechanical stability of the polymer. [2] The combination of 3D-printing with suitable polymer scaffolds and suitable ILs enables the design of membrane materials with precisely controlled sizes, shapes and geometries along with the necessary electrochemical performance. [3]The aim of this work therefore is the synthesis and characterization of protic amine-based ILs for proton conduction. All compounds are ILs at room temperature. Their ionic conductivities range between 10-2 – 10-4 S/cm. Moreover, with wide electrochemical and thermal stability windows (ΔE up to 3 V, Tg around -90 °C and Td over 200 °C) these ILs are promising for ion transport in fuel cell membranes above 100 °C. The corresponding transparent and flexible IGs display promising thermal and mechanical stability and reach ionic conductivities of up to 10-3 S/cm at elevated temperatures. Moreover, this study also demonstrates that the IGs can be obtained and structured using 3D-printing; this clearly enables the design of many materials with different requirements by simply adapting the size and shape.[1] A. Martinelli, A. Matic, P. Jacobsson, L. Börjesson, A. Fernicola, S. Panero, B. Scrosati, H. Ohno, J. Phys. Chem. B, 2007, 111, 12462.[2] Y.-S. Ye, J. Rick, B.-J. Hwang, J. Mater. Chem. A, 2013, 1, 2719.[3] K. Zehbe, A. Lange, A. Taubert, Sustainable Energy Fuels, submitted.

Comparison of the Extraction Efficiency of Isoflavone Compounds from Puerariae lobatae by Ionic Liquids with 11 Anions and 8 Imidazolium-Based Cations.

Although the field of natural product extraction with ionic liquids (ILs) is already a crowded one, the guiding rules regarding the selection of suitable ILs for extraction are still lacking. In this study, the extraction capacity of 32 ILs was investigated using Puerariae lobatae as a testing material, namely, 11 [BMIM]-based, 9 [CMIM]-based, 8 [CnMIM][Br] and 8 [CnMIM][BF4] ILs (n = 2, 4, 6, 8, 10, 12, 14, 16) were studied. Three series of concentrations (0.02, 0.50, 2.00 M) were investigated, and the results demonstrated that the extraction capacity increased with the rising IL concentrations except for 1-butyl-3-methyl-imidazolium tosylate ([BMIM][Tos]). Generally, all the 0.50 and 2.00 M ILs led to the best extraction results. At low concentrations, the IL extraction capacity is strongly dependent on the anions and cations. However, the relationship between extraction capacity and anions or cations gradually becomes weak as increasing IL concentrations. Finally, the solution of ILs was prepared in aqueous or 60% methanol depending on the solubility. The pH can vary from strong acid to weak alkaline. Extraction capacity of 32 ILs varying in concentrations has a good negative correlation with the pH, except for five [BMIM]-ILs.

PC-SAFT/UNIQUAC model assesses formation condition of methane hydrate in the presence of imidazolium-based ionic liquid systems

One of the major problems in flow assurance, especially in the case of deep subsea pipelines, is the accumulation of gas hydrates that leads to significant issues such as pipe plugging and cracking. Utilization of thermodynamic inhibitors is an effective method to prevent hydrate formation in pipelines. Recently, ionic liquids (ILs) have been recognized as new hydrate inhibitors due to their strong electrostatic charges, which form hydrogen bonds with water molecules. In this work, the capability of the PC-SAFT/UNIQUAC model combined with the van der Waals-Platteeuw theory is assessed for estimation of the methane hydrate dissociation temperatures in the presence of various IL solutions. Five pure-component parameters of PC-SAFT EOS for ILs are fitted by using experimental data of liquid density. Furthermore, vapour-liquid and hydrate equilibria experimental data are employed to adjust the binary interaction parameters of the PC-SAFT EOS (kij) and the UNIQUAC model (uij), respectively. Methane hydrate dissociation temperatures are successfully forecasted by using the proposed model for ten (10) IL systems with different concentrations in which the overall average absolute deviation for temperature (AADT %) of the model is lower than 1.5%. The results clearly demonstrate that the developed thermodynamic model is capable of precisely obtaining the methane hydrate dissociation temperatures in the presence of IL solutions, though, for [EMIM][Cl] solutions with a concentration of more than 30 wt%, the model overestimates the methane hydrate conditions. The proposed thermodynamic modeling strategy can assist to screen suitable IL solutions with an optimal composition for hydrate formation inhibition in terms of technical, economic, and environmental prospectives.

COSMO‐RS based ionic liquid screening for the separation of acetonitrile and ethanol azeotropic mixture

AbstractBACKGROUNDThe selection of competent entrainer is very important for separating azeotrope systems by extractive distillation. Ionic liquids (ILs) are outstanding entrainers due to their excellent properties. However, it is time‐consuming to choose suitable ILs from the huge database of anions and cations. Herein, the selectivity and viscosity of ILs were combined as double standards to select suitable ILs for the separation of acetonitrile and ethanol mixture.RESULTSThe selectivity and viscosity of 450 ILs (25 cations and 18 anions) were predicted based on Conductor‐like Screening Model for Real Solvents (COSMO‐RS). 1‐Butyl‐3‐methylimidazolium acetate [BMIM][Ac] was selected as a potential entrainer due to its higher selectivity and lower viscosity and [BMIM][Cl] was chosen as a comparison item as ILs with [Cl]− anion have separation performance next to [Ac]−‐based ILs. The vapor–liquid equilibrium (VLE) data of the acetonitrile + ethanol + ILs systems were determined at 101.3 kPa and correlated with the non‐random two‐liquid (NRTL) model. The result showed that the addition of the two ILs produced a salting‐out effect on acetonitrile and enhanced the relative volatility of acetonitrile to ethanol. Furthermore, [BMIM][Ac] exhibited better separation performance than [BMIM][Cl] and our previous reported ILs, which are consistent with the predicted results. The reduced density gradient (RDG) method indicated that hydrogen bonding dominated the interactions between ethanol and IL.CONCLUSION[BMIM][Ac] is a superior entrainer for the separation of acetonitrile–ethanol azeotrope. Compared to the previously studied ILs, there is a stronger hydrogen bond between ethanol and [BMIM][Ac]. This makes ethanol ‘bundled’ and acetonitrile more volatile, resulting in the superior separation performance of [BMIM][Ac]. © 2019 Society of Chemical Industry

Identifying suitable ionic liquid electrolytes for Al dual-ion batteries: role of electrochemical window, conductivity and voltage

A design strategy for suitable electrolytes for Al dual-ion batteries based on electrochemical window (ECW), conductivity and voltage calculations.

Synthesis, Characterization, and Antimicrobial Toxicity Study of Dicyanamide-Based Ionic Liquids and Their Application to Liquid–Liquid Extraction

Four different dicyanamide-based ionic liquids (ILs), [Cnmpy][DCA] (n = 4, 6, 8, and 10), were synthesized, characterized, and used to separate ethylbenzene from n-octane. Equilibrium data for the corresponding ternary systems were measured at 313.15 K under atmospheric pressure. A higher selectivity is observed for lower aromatic concentrations in the feed (20% max); this is a key factor in selecting a suitable IL. The distribution ratio and selectivity obtained in this work are comparable to those of commercial solvents. The nonrandom two-liquid model (NRTL) was successfully used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. Moreover, the antimicrobial activities of the ILs were evaluated by examining their 50% effective concentrations (EC50) using the standard microbroth dilution test against four human bacterial pathogens. 1-Butyl 3-methylpyridinium dicyanamide [C4mpy][DCA] was found as the most suitable IL among those investigated because of i...

Mechanism Analysis for Separation of Cyclohexane and tert-Butanol System via Ionic Liquids as Extractants and Process Optimization

Ionic liquids (ILs) are used in separation of organic substances in industry. In order to screen suitable ILs for industrial separation, the interaction between molecules is studied based on the ex...

Structure optimization of tailored ionic liquids and process simulation for shale gas separation

AbstractShale gas, as a potential substitute for energy source, requires important processing steps before utilization. The most common separation technology applied is distillation, which is energy‐intensive. With good stability, non‐volatility, and tailored properties, ionic liquids (ILs) are regarded as novel potential solvents and alternative media for gas absorption. Therefore, a new strategy for hybrid shale gas separation processing, where IL‐based absorption together with distillation is employed for energy‐efficient and cost‐economic gas processing, is developed. In this work, a three‐stage methodology for shale gas separation process is proposed: IL screening, where a systematic screening method with two options (database screening and computer‐aided design based on universal quasichemical functional‐group activity coefficient model) is established; suitable ILs are selected as promising candidates; process design and simulation, where separation schemes and important design issues in the IL‐based processes are determined; and, process evaluation, where the performance of the final separation process is evaluated and verified.

Silicone Elastomers with High‐Permittivity Ionic Liquids Loading

The most obvious challenge facing current dielectric elastomers (DEs) is the high driving voltages necessary to activate them, and so, an effective way to overcome this shortcoming is to increase their dielectric permittivity. Herein, high‐permittivity dielectric elastomer materials are prepared by synthesizing silicone elastomer loaded with ionic liquids (ILs). The influence of the structure and the amounts of ILs on the material properties is discussed, and important properties for material applications as DEs, such as dielectric permittivity, gel fraction, and mechanical properties, are also investigated. It is found that 1‐butyl‐3‐methylimidazolium hexafluoroantimonate (BmimSbF6) is the most suitable IL for the given system. The dielectric permittivity of the material with 90 parts per hundred rubber (phr) BmimSbF6 is 3.2 times higher than that of the pristine silicone elastomer, whereas the dielectric permittivity of pure silicone elastomer and elastomer loaded with ILs decreases in line with increased temperature in all cases. Young's modulus decreases in line with the increasing amount of BmimSbF6 in the elastomer, as expected. A simpler figure of merit (F*om) for actuators is used, and F*om of the elastomer with a 90 phr IL loading is 10.40, thereby indicating that the material has a great advantage when used in actuators.

High Performance Li‐ion battery Anodes based on Si Nano core in an LATP Matrix with better Electrolyte Compatibility and Temperature Resistance

AbstractNovel core/matrix morphologies of Silicon nanostructures/ LATP ceramics are synthesized through a sol ‐ gel assisted method. The Li1.3 Al0.3 Ti1.7(PO4)3 powders were coated on Si nanoparticles as an artificial SEI layer selectively conducting Li cations, which also prevents the formation of the thick natural SEI layer formation, improving the cyclic stability. The composite anodes exhibited a specific capacity of discharge capacities of 1789 mA h g−1 at 0.1 C in the ionic liquid electrolyte LiTFSI‐Pyr14TFSI. They cycle 500 times with a capacity retention of more than 75%. It is assumed that the promising electrochemical characteristics of the composite anode films are due to the absence of direct contact between the Si nanoparticles and the electrolyte and the presence of LATP providing an efficient and quick pathway for lithium ion transport and acts as a Li ion reservoir. The electrodes also show promising results with suitable ionic liquid based electrolytes at high temperature. Hence the conclusions from the present study projects LATP−Si composite films as a promising anode material for LIBs, with high capacities and long cycling stabilities at room temperature as well as high temperature.

Tuning the CO2 adsorption by the selection of suitable ionic liquids at ZIF-8 confinement: A DFT study

Abstract Development of suitable materials for CO2 storage and conversion has gained tremendous attraction in the past decade. Metal organic frameworks (MOFs) has emerged as suitable porous materials in this aspect. Ionic liquids (ILs) can be confined at the pores of MOFs and these composites are well known for gas storage and separation applications. Here, 1-butyl 3-methylimidazolium ([BMIM]+) based ILs@ZIF-8 composites were studied using density functional theory (DFT) based approach for the identification of suitable composite for CO2 capture. The adsorption of CO2 has been studied at isolated ILs at gas phase and the same at confined state (i.e. ZIF-8). It is interesting to note that the adsorption behavior of CO2 at these two environments differ from each other. In gas phase, hydrophilic ILs shows more CO2 adsorption whereas in the confined state hydrophobic ILs shows dominant adsorption. This is due to the similar hydrophobicities of ZIF-8 and ILs, which play an important role in tuning CO2 adsorption at the composite. Fluorine containing ILs ([BMIM]+ with [BF4]− and [PF6]− anions) are showing better adsorption of CO2 at higher concentration. Our calculations reveal that the adsorption of CO2 depends on the nature of ILs present in the confined environment. Also we observed maximum adsorption capacity for the empty ZIF-8 and ILs@ZIF-8 composites. The present findings can be helpful to predict the selection of ILs for the CO2 selectivity at suitable solid-liquid interface.

Assessment of thermal and transport properties of ionic liquids as suitable absorbent for absorption cooling applications

Ionic liquids, salts which have liquid phase at temperature below 100°C, have been widely introduced in engineering applications, including absorption cooling systems. The application of ionic liquids in absorption cooling systems is intended to remove the disadvantages of conventional working fluids such as corrosion and crystallization. In terms of thermodynamic performances, theoretical investigation based on solubility behavior of ionic liquids in natural refrigerants show a competitive performance in comparison with conventional working fluid. Nevertheless, heat transfer performance, which is also an important key in absorption cooling systems, particularly in terms of system design and size, needs to be deeply explored and investigated. This study aims to assess the thermal and transport properties of ionic liquids as absorbent in relation to the heat and mass transfer characteristics of these working fluids. The thermal and transport properties of ionic liquids proposed as absorbent for absorption cooling systems are collected, and heat and mass transfer characteristic of these ionic liquids based on their thermal and transport properties are investigated and analyzed. Finally, the most suitable ionic liquids for absorption machines, both in terms of thermodynamics and heat and mass transfer performances can be proposed.

Screening of Suitable Ionic Liquids as Green Solvents for Extraction of Eicosapentaenoic Acid (EPA) from Microalgae Biomass Using COSMO-RS Model.

Omega-3 poly unsaturated fatty acids (PUFA) particularly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have many health benefits including reducing the risk of cancer and cardiovascular disease. Recently, the use of ionic liquids (ILs) in lipid extraction from microalgae provides the potential to overcome common drawbacks, offers several other benefits. To date, very limited researches are available to focus on extracting microalgae lipid and PUFA in particular by using ILs. The objective of current work is to screen the potential ILs that can be applied in EPA extraction. In this study, fast ILs screening was performed with the help of a conductor like screening model for real solvents (COSMO-RS) and the ILs with higher capacity values for use in extraction of EPA were compared. According to the results, the highest capacity for EPA extraction among 352 screened cation/anion combinations belongs to [TMAm][SO4]. It is expected to achieve a higher yield of EPA once applying this combination as the solvent in the process of extraction. ILs with small anions were observed to have higher capacities, as well possessing higher charge density compared to larger ones, and therefore, they are more preferable for extraction purposes. Moreover, shorter alkyl chain cations are preferred when using imidazolium-based IL, which agrees with experimental data.

MoDoop: An Automated Computational Approach for COSMO-RS Prediction of Biopolymer Solubilities in Ionic Liquids.

An automated computational framework (MoDoop) was developed to predict the biopolymer solubilities in ionic liquids (ILs) on the basis of conductor-like screening model for real solvents calculations of two thermodynamic properties: logarithmic activity coefficient (ln γ) at infinite dilution and excess enthalpy (HE) of mixture. The calculation was based on the optimized two-dimensional structures of biopolymer models and ILs by searching the lowest-energy conformer and optimizing molecular geometry. Three lignin models together with one IL dataset were used to evaluate the prediction ability of the developed method. The evaluation results show that ln γ is a more reliable property to predict lignin solubilities in ILs and the p-coumaryl alcohol model is considered as the best model to represent lignin molecules. The developed MoDoop approach is efficient for rapid in silico screening of suitable ionic liquids to dissolve biopolymers.

Bioplastic electromechanical actuators based on biodegradable poly(3-hydroxybutyrate) and cluster-assembled gold electrodes

We present the fabrication and characterization of electroactive actuators based on natural-derived bioplastic able to display reversible bending deformations in response to low intensity electric fields. We used biodegradable poly(3-hydroxybutyrate) (PHB) blended with a suitable ionic liquid to produce freestanding electroactive ionogel layers through a solvent casting process employing non-toxic solvents. The ionogels were provided with compliant cluster-assembled gold electrodes fabricated by means of supersonic cluster beam deposition (SCBD). These metal layers exhibit tailored electrical properties, large surface areas and mechanical resiliency against deformations. The manufactured actuators were characterized in terms of mechanical, morphological, electrochemical and electromechanical properties. We show that the mechanical properties of the ionogels are similar to those of low density polyethylene, while the actuators demonstrated large bending displacement and stable operational durability. Furthermore, due to the use of PHB in combination with a hydrophobic ionic liquid, the actuators did not exhibit hygroscopic behaviour.