The Path Ahead for Ionic Liquids

Ionic liquids are designer molecules which can efficiently replace the conventional organic solvents used in chemical processes and operations. Although a number of such applications have been reported in the literature for almost a decade, very few have actually been commercialized. This paper details the different applications claimed and examines the issues and barriers which obstruct the rapid commercialization of ionic liquids. It identifies further courses of action required for the assessment and realization of the advantages of ionic liquids.     

First Studies on the Rheological Behavior of Suspensions in Ionic Liquids

The suspension rheology of hematite in the ionic liquid Ecoeng^TM.212 was studied in detail and compared to the pure ionic liquid. This is the first report on the rheological behavior of suspensions in ionic liquids, and it is postulated that colloidal stability and rheology must be considered to understand these results, and to overcome limitations on the production of nanosized particles in industrial applications. Concentrated suspensions of particles in the nanometer range show non‐Newtonian flow behavior including shear thinning and shear thickening. These phenomena are mainly caused by particle‐particle interactions in the suspension, and control of these interactions is critical. The influences of temperature and solid concentration on flow behavior were shown for the pure liquid and the suspensions. It is seen that the ionic liquid follows the Arrhenius equation for non‐associating electrolytes. It is possible to shift all hematite suspension curves to a master curve according to the model of Gleißle and Baloch. Furthermore, the flow behavior of the suspensions can be modeled with the well‐known Herschel‐Bulkley plot. A 10 wt % suspension of Fe₂O₃ follows Newtonian behavior over the entire range, similar to the pure ionic liquid. It is believed that the ionic liquid has an influence on the stability of the particles, leading to a decrease of attractive particle‐particle forces.     

离子液体中硝基苯的传质特性

应用循环伏安法测定了离子液体中硝基苯的扩散系数。硝基苯在离子液体中电还原,其扩散系数受硝基苯、离子液体及水的相互作用影响,随内外条件变化呈现复杂的变化规律。随硝基苯浓度增加扩散系数减小;相同硝基苯浓度时,水的浓度增加扩散系数增大;随着温度升高硝基苯扩散系数增大。     

Synthesis and Characterization of Pt/C Nanocatalysts Using Room Temperature Ionic Liquids for Fuel Cell Applications

Carbon supported Pt nanocatalysts are prepared using different room temperature ionic liquids (RTILs) as the solvent and conventional preparation techniques, based on wet impregnation methods. The Pt/C nanocatalysts are characterized by XRD, TEM, EDX, and XPS. The results of the analyses show that the Pt/C catalysts, using different RTILs as solvents, are homogeneously dispersed with a narrow size distribution. The electro‐oxidation of liquid methanol on these catalysts is investigated at room temperature by cyclic voltammetry and chronoamperometry. The results have shown that the Pt/C catalysts prepared using RTILs are more active than the other Pt/C catalysts prepared by the authors. Surface area measurements of the Pt metal, conducted by electro‐oxidation of preadsorbed CO, indicate that catalysts prepared using RTILs as the solvents have higher surface area. The Pt/C nanocatalysts, prepared using RTILs, exhibit enhanced activity for the methanol oxidation reaction, compared with the Pt/C catalysts prepared by the impregnation method and commercial Pt/C catalysts.     

Kinetics of Decomposition of Energetic Ionic Liquids

The Arrhenius‐type reaction rate parameters for the initiation reactions governing the thermal decomposition of several energetic ionic liquids (EILs) were determined by numerical techniques. The compounds chosen for this purpose were the energetic 4‐amino‐1,2,4‐triazolium nitrate (4ATN) and 1‐hydroxyethyl‐hydrazinium nitrate (HEHN). The supplementary compounds studied for comparison were 4‐amino‐1,2,4‐triazolium chloride (4ATCl) and ammonium nitrate (AN). The reaction rate parameters were obtained by an evolutionary genetic algorithm (GA) that compared the difference between the experimental and simulated species evolution profiles from the decomposition process. The experimental data were generated by confined rapid thermolysis (CRT). The decomposition process was simulated by applying conservation equations to the condensed and gas phases individually. The optimization module recovered the experimental species profiles with reasonable accuracy for all the compounds studied. The processes governing the decomposition of these energetic compounds were found to be autocatalytic in nature, and the autocatalytic agents were the strong acids generated by the initial decomposition step. The activation energy and pre‐exponential factor for the unimolecular decomposition step for 4ATN, HEHN, and 4ATCl were 167–188 kJ mol⁻¹ and 10¹⁶ s⁻¹, respectively, similar to previously determined values for AN.     

离子液体脱硫研究

当今世界脱除油品中的含硫化合物是人们最关注的话题。其中,离子液体受得到了广泛的应用,它是一种绿色环保化工试剂,尤其是在脱硫技术方面取得了显著效果。主要介绍了离子液体的种类、优点、脱硫反应机理及脱硫方式。     

ATR-FTIR Measurement of Biomass Components in Phosphonium Ionic Liquids

Abstract

Qualitative and quantitative measurements of biomass components dissolved in the phosphonium ionic liquids (ILs), trihexyltetradecylphosphonium chloride ([P66614]Cl) and tributylmethylphosphonium methylsulphate ([P4441]MeSO₄), are obtained using attenuated total reflectance-FTIR. Absorption bands related to cellulose, hemicelluloses, and lignin dissolution monitored in situ in biomass-IL mixtures indicate lignin dissolution in both ILs and some holocellulose dissolution in the hydrophilic [P4441]MeSO₄. The kinetics of lignin dissolution reported here indicate that while dissolution in the hydrophobic IL [P66614]Cl appears to follow an accepted mechanism of acid catalyzed β-aryl ether cleavage, dissolution in the hydrophilic IL [P4441]MeSO₄ does not appear to follow this mechanism and may not be followed by condensation reactions (initiated by reactive ketones). The measurement of lignin dissolution in phosphonium ILs based on absorbance at 1510 cm^?1 has demonstrated utility. When coupled with the gravimetric Klason lignin method, ATR-FTIR study of reaction mixtures can lead to a better understanding of the delignification process.     

1-丁基-3-甲基咪唑四氟硼酸盐分子结构理论研究

采用密度泛函理论,在B3LYP／6—311＋＋G（d,p）水平下,计算得阳离子1-丁基-3-甲基咪唑[Bmim]＋与阴离子四氟硼[BF4]-分子内结合能-338．03kJ／mol,同时运用AIMNBO理论探究其分子内成键原理。     

Recent Developments and Applications of Ionic Liquids in Gas Separation Membranes

Flue gas emissions and the harmful effects of these gases urge to separate and capture these unwanted gases. Ionic liquids due to negligible vapor pressure, thermal stability, and wide electrochemical stability have expanded its application in gas separations. A comprehensive overview of the recent developments and applications of ionic liquid membranes (ILMs) for gas separation is given. The three general classifications of ILMs, such as supported ionic liquid membranes (SILMs), ionic liquid polymeric membranes (ILPMs), and ionic liquid mixed‐matrix membranes (ILMMMs) along with their applications, for the separation of various mixed gases systems is discussed in detail. Furthermore, issues, challenges, computational study, and future perspectives for ILMs are also considered.     

Ionic Liquids for Propene‐Propane Separation

This paper presents an extensive study on the feasibility of ionic liquids (IL) for the extractive distillation of propene‐propane mixtures. A new experimental method for express screening of non‐volatile entrainers was elaborated. A series of ILs and their mixtures were screened at ambient temperature and low pressures. The screening results show that every tested IL turns a low boiler propene into a high boiler and the alkene‐to‐alkane separation factor can be as low as 0.28. The solubility and separation efficiency can be tuned by adjusting the chemical structures of the ions forming the IL. It was found that shortening of the alkyl substituents of the imidazolium ions leads to a decrease in capacity and to an increase in the separation factor. Interestingly, ILs containing nitrile functionalities in either the cation or the anion showed, in our experiments, enhanced separation ability combined with still good capacities. From our thermodynamic measurements, [EMIM][[B(CN)₄] was proved to be the most promising candidate. Binary mixtures of ILs were also tested and resulted in separation factors and capacities between the values for the individual ILs. For the most promising candidates, also autoclave measurements at elevated temperatures and pressures were carried out. These experiments indicate that the separation ability decreases with growing temperature and loading. In general, our study definitely proves the high potential of ILs to act as entrainers in the extractive distillation of propene‐propane mixtures or for the separation of any other low‐boiling alkene‐alkane mixture.     

Electron Microscopy Imaging Applications of Room Temperature Ionic Liquids in the Biological Field: A Review

For biological imaging using electron microscopy (EM), the use of room-temperature ionic liquids (RTILs) has been proposed as an alternative to traditional lengthy preparation methods. With their low vapor pressures and conductivity, RTILs can be applied onto hard-to-image soft and/or wet samples without dehydration – allowing for a more representative, hydrated state of material and opening the possibility for visualization of in situ physiological processes using conventional EM systems. However, RTILs have yet to be utilized to their full potential by microscopists and microbiologists alike. To this end, this review aims to provide a comprehensive summary of biological applications of RTILs for EM to bridge the RTIL, in situ microscopy, and biological communities. We outline future research avenues for the use of RTILs for the EM observation of biological samples, notably i) RTIL selection and optimization, ii) applications for live cell processes and iii) electron beam and ionic liquid interaction studies.     

Ionic Liquids as Modifying Agents for Protein Separation in Centrifugal Partition Chromatography

Aqueous two‐phase systems (ATPSs) can be applied in centrifugal partition chromatography (CPC) to separate biomolecules. Two ionic liquids (ILs) served as modifying agents to tune partition coefficients in the separation of two model proteins, myoglobin and lysozyme. Myoglobin was not affected by the ILs, while the partition coefficient of lysozyme was lowered with addition of IL. High stationary phase retention was achieved with ATPSs in a CPC column with cell size and geometry specially designed for unstable biphasic systems. When ILs were used as modifying agents, no notable decrease in stationary phase retention was observed. The injection volume was increased to 20 % of the total column volume and process simulations indicate that a further increase in the injection volume is possible.     

Ionic Liquids for Chloromethane/Isobutane Distillative Separation: Express Screening

The present study centres on room‐temperature ionic liquids (ILs) as entrainers in extractive distillation of chloromethane/isobutane mixtures. The binary system, chloromethane/isobutene, is an azeotropic system. In this study, IL entrainers are shown to be able to break the azeotrope and, thus, assure the separation in the whole range of chloromethane/isobutane ratios. ILs formed from different cations and anions are considered and their influence on chloromethane/isobutane separation is explored. Among the ILs studied, those containing the trifluoromethanesulfonate ([CF₃SO₃]^–) or tricyanomethanide ([C(CN)₃]^–) anion are demonstrated to exhibit an enhanced potential for chloromethane/isobutane separation compared to the corresponding ILs based on the bis(trifluoromethylsulfonyl)imide ([Tf₂N]^–) anion. Moreover, the ILs enclosing these anions are cheaper than those with the [Tf₂N]^– anion. Thus, the separation ability, solubility of chloromethane/isobutane mixtures, and costs of IL entrainers can be adjusted by the right choice of cations and anions.     

Separation of Lactic Acid through Polymer Inclusion Membranes Containing Ionic Liquids

Optically pure lactic acid that can be prepared by fermentation is one of the important raw materials for biodegradable polymer. Since an economical technique is desired that separates lactic acid from the fermentation broth, we proposed lactate permeation through a poly(vinyl chloride)(PVC)-based membrane containing ionic liquids as a carrier. Lactate was successfully permeated through polymer inclusion membranes (PIMs) containing Aliquat 336, Cyphos IL -101, and -102 as ionic liquids. From the viewpoints of permeation rates and the pH drop of the feed phase, Aliquat 336 was the best ionic liquid. Based on the experimental results, we calculated the overall mass transfer coefficients and evaluated the contribution of membrane resistance to the overall permeation resistance. Furthermore, permeation behavior was explained by the solution-diffusion model. The superior stability of PIMs over the supported ionic liquid membranes was observed for membranes containing Aliquat 336 as a carrier. The PVC-based membrane process containing Aliquat 336 was found to be promising for lactate separation on an industrial scale.     

离子液体的应用

离子液体是室温下呈液态的离子化合物,是一类新型的"软"功能材料或介质,具有优良的可设计性,它作为一种绿色溶剂,具有很多独特的物理化学性能。介绍了离子液体在纤维素科学、有机反应、分离过程、电化学中的应用。     

固载化离子液体制备方法的研究进展

近年来,集均相和非均相材料的优点于一身的固载化离子液体一直是化学家们研究的重点之一.本文概述了固载化离子液体制备方法的研究进展.     

Effect of Operating Parameters on the Separation of Sugars by Nanofiltration

ABSTRACT

Due to the complexity of fermentation mixtures, separation of solutes and secondary substrates has a special importance. Membrane processes such as nanofiltration may offer good alternatives for the separation of fermentation products or recovery of substrates. For an efficient separation, the membrane type and operating parameters such as feed flow rate, operating pressure, and feed should be optimized. In this study the separation and recovery of sugars were targeted. It was found that with an increase of the feed flow rate, permeate flux increased since the effect of concentration polarization was minimized. As a result, experiments were carried out at the highest possible flow rate. The effect of pressure was studied at five pressures (10–50 bar). It was found that there is a linear relationship between the pressure and permeate flux up to 30 bars. Beyond 30 bars the effect of pressure became less significant. Thus, 30 bars was chosen as the operating pressure. To investigate the effect of concentration, 1 to 10 weight percentage sucrose and glucose solutions were utilized. It was observed that with an increase in concentration, permeate flux decreased and rejections increased, finally reaching a limiting value. Binary solutions of sucrose and glucose were also studied. It was seen that the separation factor slightly decreased, probably due to a glucose–sucrose interaction. Experimental data were used with a mathematical model to predict the permeate flux and rejection. Good agreement of the predicted results was obtained with the experimental data for a 500 MWCO membrane     

离子液体在溶解方面的研究进展

离子液体作为一种新型的“绿色溶剂”,广泛应用于化学反应、萃取分离等化工过程。介绍了绿色溶剂——离子液体发展状况,详细讨论了离子液体在溶解方面的研究进展,包括离子液体在萃取分离方面的研究、离子液体作为反应过程中的溶剂以及离子液体作为高分子溶剂的研究。     

离子液体在电化学生物传感器中的应用

介绍了新型材料离子液体的组成及性质,从室温离子液体的碳电极、Sol-Gel材料和聚合物材料等几方面介绍了离子液体在电化学生物传感器中的应用。     

离子液体及其在电化学中的应用

离子液体即在室温或接近室温下呈液态的完全由离子构成的物质,作为环境友好和“可设计性”溶剂正在引起越来越多的重视。它具有熔点低、蒸汽压小、酸性可调及良好的溶解度、粘度和密度等特点。综述了离子液体的组成、分类、性质、制备和纯化,就离子液体在电池技术、电合成、电沉积、电容器等电化学方面的应用和研究进展加以阐述,并对该领域的研究前景作了展望。