Ionic Liquid Membranes for Carbon Dioxide Separation

Mucosal barriers are a natural defense system for preventing the entry of foreign objects into the body; however, they pose obstacles for effective drug delivery. Coated polymer nanoparticles (NPs) have been shown to possess improved rates of diffusion across mucus compared to their uncoated, or bare, counterparts. Choline carboxylic acid-based ionic liquids (ILs) are highly tunable and show high biocompatibility and mucus modulation properties, making them an ideal choice for the improvement of NP diffusion through mucosal barriers. This study aimed to investigate whether the use of choline-based ILs has a positive effect on the dispersibility of poly(lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG-PLGA), and poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) NPs through nasal mucus by using a multiple particle tracking method. The samples, according to the IL used, showed altered rates of diffusion in both aqueous and mucosal environments. The use of CA2HE 1:1 with PEG-PLGA NPs slowed NP diffusion, while the use of the same IL increased diffusion for PEG-PLA. Additionally, UV-vis spectroscopy was used to identify the possible formation of complexes between the mucin polymer and NPs. Circular dichroism (CD) spectroscopy was used to analyze any potential changes in the secondary structure of mucin as a result of the introduction of polymeric NPs. It was demonstrated that the use of an IL can stabilize the interactions between polymer NPs and mucin polymers. Isothermal titration calorimetry was used to obtain quantitative measurement of the binding energies between NPs and mucus and serves to confirm the results obtained from CD spectroscopy. Last, an ex vivo porcine nasal mucosa model was used to explore their use in a nasal delivery context, disclosing a possible connection between the use of zwitterionic transport materials and more effective drug delivery. This research demonstrates the potential of choline carboxylic acid-based ILs to control the transport behavior of polymer NPs for intranasal drug delivery.

Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions are of extensive interest in chemical synthesis. While the use of ionic liquids (ILs) as solvents for synthesis has been widely explored in recent years, the understanding of their influence on the mechanism and reactivity of CuAAC reactions remains poorly understood. Here, we investigate the kinetics of a phenylacetylene-benzylazide and acetylene-benzylazide CuAAC reaction to probe the influence of IL structure, including the role of the base used to promote the reaction and the importance of water content. The use of 'wet' ILs led to remarkable changes in the kinetic profile of the reaction by eliminating the initial induction period. The reaction rate was found to be dependent on the copper(I) source. The effect of an added base was also studied, with the use of a tertiary amine-bearing IL leading to high conversions in under 5 min at ambient temperature. The results of this study highlight the nature and complexity of CuAAC reactions in ILs. As more ILs are getting involved in industrial processes, the data obtained from this study are valuable for better understanding processes that affect the CuAAC reaction in IL media and for creating customized systems for organic synthesis, thus improving the efficiency and sustainability of such processes.

The diversity and intensity of ionic liquid (IL) research in the Australasian region has mirrored that worldwide, as these unique materials move from simply being conceptually interesting, to valuable commodities for many different areas of application. The presentations in the 5th Australasian Symposium on Ionic Liquids (ASIL-5) reflected the variety of research in the field and highlighted the exciting promise of ILs in applications ranging from electrochemistry to green chemistry, corrosion resistance to pharmaceutical salts. The fifth in the series of the very successful AustralasianSymposium on IonicLiquidswas held on the3rd–4th May 2012 in Clayton, Australia. The symposium was co-hosted by theARCCentre of Excellence for Electromaterials Science at Monash University, CSIRO and the Monash Ionic Liquids group. The symposiumwas initiated in 2003 and has remained a magnet for world-leaders in the field as well as a friendly forum for young students and researchers to present their work. International speakers at ASIL5 included Professor Hiroyuki Ohno, Tokyo University of Agriculture and Technology, Professor Frank Endres, Clausthal University of Technology, Professor Suojiang Zhang, Chinese Academy of Sciences, Professor EdwardMaggin, University of Notre Dame, Professor Toshiyuki Itoh, Totteri University, and Professor Sergey Verevkin, University of Rostock. The symposium also featured speakers from CSIRO and a range of Australian universities including Curtin University, Deakin University, Monash University, the University of Newcastle, the University of New South Wales, and the University of Sydney. Contributions from an invited selection of speakers are presented here, in this special IL issue of the Australian Journal of Chemistry – an International Journal for Chemical Science. The electrochemical applications of ILs have always been one of the leading interests in the field, particularly their use for electrodeposition and battery applications. Endres and coworkers, have shown that polycarbonate templates can be used within a chloroaluminate-based IL for the electrodeposition of aluminium nanowire electrodes. These electrodes show promising properties for use as anodes in lithium ion batteries, with good mechanical stability after 50 cycles in an IL-based electrolyte. Additives within chloroaluminate-based ILs can also influence the nucleation process, morphology, and crystallinity of aluminium electrodeposits, as reported by Zhang et al. Endres and coworkers also show that lithium can be deposited onto copper electrodes modified with polystyrene sphere opals, using an air and water stable IL-based medium, producing lithium either as hollow spheres or with a macroporous structure. This work highlights the complex nature of electrodeposition from ILs, and also points the way towards high surface area lithium electrodes that could be useful for rechargeable lithium metal micro-batteries. The use of ILs in lithium metal batteries is attracting increasing interest, particularly from a safety perspective as many ILs are non-flammable. One important aspect of this research involves understanding any chemical reaction between the lithium metal and the IL, normally assessed during or after cycling the battery. A novel approach is discussed here by Bhatt and coworkers, who report a significant influence of storage time on the morphology and performance of lithium electrodes in an IL/lithium salt medium. This indicates that for use of ILs in practical battery applications, the periods when the battery is not in use may also impact the performance.

Some of the most critical issues facing the nanocomposite community include the need for multi-scale imaging of hierarchical structures, effective methods for controlling nanoparticle chemistry and surface-energy, and efficient processing methods for preparing nanoparticles and nanocomposites. Over the last decade we have employed a number of approaches to address some of these challenges. This paper will review our efforts centered on the use of ionic liquids and fluorescence microscopy to develop tools to enable industry to more quickly bring new nanocomposite-based products to market. Research results focused on polymer nanocomposite based on multiwalled-carbon-nanotube (MWCNT), Montmorillonite (MMT) and nanofibrillated-cellulose (NFC) will be presented.

Although the use of ionic liquids (IL) in polymeric membranes is known to elevate the electrochemical performance for proton exchange membrane-based fuel cells (PEMFC), they suffer from drawbacks such as IL drain and lowering in mechanical properties that lead to deterioration in PEMFC performance. To mitigate these issues, we report, for the first time, the use of polymeric ionic liquid (PIL), namely, poly(diallyl dimethyl ammonium trifluoride methane sulphonate) (P[DADMA][TFMS]) to be blended with polybenzimidazole (PBI-I) as a membrane material for PEMFC. PBI-I and (P[DADMA][TFMS]) were chosen because they form miscible blends and are suitable for acid doping as a matrix, which can eventually be used as proton conductor. The structure, miscibility and inter-polymer interactions were studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The increase in proton conduction in comparison to the PBI membranes was observed due to the presence of ionic groups of PILs in blend membranes. With the increase in PIL content, the proton conductivity of the composite membranes gradually increased from 0.04 S cm−1 for PBI to 0.07 S cm−1 for the blend membrane at 150 °C. The MEAs were fabricated with PBI-I, PBI-PIL15, PBI-PIL25 and PBI-PIL35. Corresponding single cells were successfully tested at temperatures of 160 °C. The maximum power density and current density obtained were 515 mW cm−2 and 1632 mA cm−2, respectively, for PBI-PIL25-based MEA.

Ionic systems in materials research : new materials and processes based on ionic polymerizations and/or ionic liquids

Review: 122 refs.

Ionic-liquid-enhanced solvent extraction mechanism: A novel concept

This chapter reviews the roles of ionic liquids (ILs) in pharmaceutical manufacturing processes, including the use of ILs as solvents in the synthesis of drugs or isolation of drug intermediates, the use of ILs in pharmaceutical crystallization, in pharmaceutical separation, for the extraction of drugs from natural products, to deliver drugs, to detect drugs, and even as active pharmaceutical ingredients (APIs). ILs have also been considered as alternatives to organic solvents in the pharmaceutical industry. A large volume of volatile organic solvents (VOCs) is used in the process of drug extraction from natural products, resulting in serious environmental problems and replacement of conventional solvents by ILs might prevent the emission of VOCs. While ILs have been shown to be efficient vehicles in transdermal drug delivery, until recently they were not studied as transdermal drugs themselves because ionized salts normally diffuse poorly through lipid membranes.

INTRODUCTION The unique properties of ionic liquids (ILs) i.e. high thermal and chemical stability, non-flammability, low vapor pressure, and wider electrochemical window compared to traditional solvents, as well as the prospect that they can be tailored or custom designed for specific requirements make them all the more interesting. In recent years, ILs with organic cations have been suggested for electrolyte applications. Ionic liquids seems to be promising electrolytes in protonic systems as they exhibit good proton conducting properties.The motivation for the presented research was dictated by the growing interest in the field of the use of ionic liquids as electrolytes in metal-hydride batteries (Ni-MH) and other proton batteries (eg. based on the Si anode). The electrolytes based on ionic liquids can reduce the problem of the anode material (eg. AB5 alloy) corrosion in aqueous basic solutions, which may result in the improvement of the operation parameters of the proton batteries.The focus of this study was to check the applicability of ILs as non-aqueous electrolytes through the investigation of hydrogen sorption in Pd limited volume electrode (Pd-LVE) and AB5-LVE. Since protic ILs and their mixtures with other solvents have been recently proposed as electrolytes in metal-hydride batteries, Pd-LVE is a very good model system to carry out the preliminary study of hydrogen electrosorption in ionic liquids in view of the further research with the use of multicomponent alloys. EXPERIMENTAL The electrochemical experiments were conducted in selected, commercially available protic and aprotic ionic liquids (i.a. diethylmethylammonium triflate (DEMA-TFO), ethylammonium nitrate (EAN), 1-ethyl-3-methylimidazolium methanesulfonate (EMIm-MS) under inert gas (Ar) using three-electrode system. Pd-LVE (ca. 0.5 μm thick) or AB5-LVE (ca. 50 μm thick) was a working electrode, Ag wire was a quasi-reference electrode, and Pt or Au spiral was an auxiliary electrode. Pd-LVE were obtained electrochemically from the PdCl2 aqueous solution. AB5 alloy (LaMMNi4.1Al0.3Mn0.4Co0.45) was obtained from VARTA Microbatteries GmbH. To aprotic ionic liquid (EMIm-MS) organic acid of the same anion as in the IL (methanesulfonic acid, HMS) was added as a source of hydrogen and to increase the ionic conductivity of the obtained electrolyte. Cyclic voltammetry (CV), chronoamperometry (CA) and chronopotentiometry (CP) techniques were used to perform the electrochemical measurements. The electrodes were subjected to a hydrogen pretreatment procedure (HPP) and standard hydrogen cyclic voltammetry electrosorption experiment to obtain hydrogen absorption isotherms. RESULTS AND DISCUSSION It was observed, that the reversibility of the hydrogen sorption in Pd is significantly lower in ILs than in aqueous solutions, which may be caused by hindered proton transport due to few reasons. The first one is the high viscosity of IL, the second one is the difference of proton source, and finally the possible interactions of IL ions with the Pd electrode. Multiple hydrogen sorption in ILs (HPP) increases the reversibility of the investigated process. Preliminary HPP performed in aqueous solution of sulfuric acid facilitates further hydrogen sorption only in some cases (i.a. in EAN). Thus, it was found that the rate of hydrogen absorption is controlled rather by surface than the bulk processes. The maximum hydrogen sorption capacity (H/Mmax) obtained for Pd in protic IL (i.e. DEMA-TFO) and aprotic IL with addition of organic acid (EMIm-MS + 0.5 M HMS) is comparable with those obtained in aqueous solutions of acids and bases, reaching the value of ca 0.7. Our preliminary studies of hydrogen sorption in the AB5 alloy in a mixture of an aprotic IL with the organic acid (EMIm-MS + 1 M HMS) revealed that, as in case of Pd-LVE, the electrochemical reversibility of this process is much lower in comparison with the electrosorption measurements performed in concentrated base (Fig.1), which is due to the significant difference in ion conductivity and dynamic viscosity of the tested electrolytes. Fig. 1. Cyclic voltammetry behavior of AB5 electrode in EMIm-MS + 1 M HMS, inset: cyclic voltammetry of AB5 electrode in 6 M KOH; first cycles; 2 mVs-1. CONCLUSIONS Examined protic and aprotic ionic liquids can be effectively used as electrolytes in the hydrogen sorption process as we demonstrated by the exemplary Pd-LVE electrode. The max. H/Pd ratios obtained for DEMA-TFO and nitrate protic ILs are similar (0.6-0.7) and comparable with those measured in aqueous solutions of acids and bases. Hydrogen electrosorption from aprotic ionic liquids (eg. in EMIM-MS) with different concentration of acid gives ability to tune the maximum hydrogen capacity. The max. H/Pd ratios obtained for EMIm-MS (acid concentration ca. 0.5 M) equals to ca. 0.74 (this is the same value that was obtained for this type of electrode from acidic aqueous media). Figure 1

In the current research, the binary solution containing ionic liquid (IL), 1-ethyl-1-methylmorpholinium dimethyl phosphate ([C1C2MOR][DMP]), 1-ethyl-1-methylpiperidinium dimethyl phosphate ([C1C2PIP][DMP]), or N,N,N-triethyl-N-methylammonium dimethyl phosphate ([N1,2,2,2][DMP]) with ethanol are investigated as new working fluids for absorption refrigeration technology. The IL was mixed with ethanol, which was considered as a refrigerant. Experimental (vapor + liquid) phase equilibria (VLE) of these binary systems were measured by an ebulliometric method within a temperature range from T = (328.15 to 348.15) K with an increment of 10 K and pressures up to 90 kPa. Experimental VLE data were correlated using non-random two-liquid (NRTL) within the maximum average relative deviation of 0.45%, which confirms the effectiveness of using such a model for calculations. Each of the proposed binary systems exhibit a negative deviation from Raoult’s law, which is a very important characteristic for working pairs used in absorption heat pumps or absorption refrigerators. From a technological point of view, measurements of physicochemical properties play an important role. In this research, liquid density and dynamic viscosity were determined at temperatures from T = (293.15 to 338.15) K at ambient pressure over the whole concentration range. These properties were correlated using empirical equations. From experimental density data, the excess molar volumes were determined and correlated using the Redlich–Kister type equation. Ionic liquid: [C1C2MOR][DMP] and [C1C2PIP][DMP] were synthesized and characterized using NMR analysis. The thermophysical characterization of pure ILs, including glass transition temperature (Tg) and heat capacity at the glass transition temperature (ΔgCp), was determined using the differential scanning calorimetry technique (DSC) at atmospheric pressure. In this work, the combination of basic studies on the effect of the cation structure of an ionic liquid on the properties of their solutions with ethanol and the possibility of future application of the tested systems in a viable refrigeration system are presented.

Perspective on ionic liquids and ionic liquid membranes

Dilute sulfuric acid and acidic ionic liquids are pretreatment methods used to selectively hydrolyze hemicellulose from lignocellulosic biomasses. In this work, a comparison between these techniques is carried out by treating sugarcane bagasse both with 1-ethyl-3-methylimidazolium hydrogen sulfate at different ionic-liquid and water contents and with H 2 SO 4 at the same conditions and equivalent ionic liquid molar contents. Results from the use of ionic liquid showed that it was possible to tune the biomass treatment either to achieve high hemicellulose hydrolysis yields of 72.5 mol% to very low furan and glucose co-production, or to obtain furfural at moderate yields of 18.7 mol% under conditions of low water concentration. In comparison to the use of ionic liquid, sulfuric acid pretreatment increased hemicellulose hydrolysis yields by 17%, but the 8.6 mol% furfural yield was also higher, and these yields were obtained at high water concentration conditions. Besides, no such tuning ability of the biomass treatment conditions can be made.

Chemical flooding process has shown great potential in Enhanced Oil Recovery (EOR).Unfortunately, chemicals used have some disadvantages such as high cost, high toxicity and high adsorption tendency.In this study, we aim at using Ionic Liquids (ILs) as alternatives for traditional chemicals.Ionic liquids are salts having melting point below 100°C and they found as a liquid at room temperature.Nine Ammonium and Phosphonium based ILs were screened.The screening was based on their solubility in brines of different compositions, thermal stability and ability to reduce the aqueous-oleic phase's Interfacial Tension (IFT).The screening process flagged Ammoeng 102 as the favored ionic liquid.More investigations of Ammoeng 102 solutions indicated a sharp exponential decrease of IFT values with increasing concentration.On contrary to surfactant solutions, Lower IFT values were obtained with increasing brine salinity indicating the ILs superiority in high salinity reservoirs.Two tertiary flooding experiments were conducted using 500 ppm Ammoeng 102 diluted in 10% and 20% (w/w) brine salinity to investigate its recovery efficiency.Lower salinity secondary brine flooding provided higher recovery.The opposite trend occurred in tertiary ionic solution flooding where recovery is higher for high salinity ionic solution indicating the effectiveness of ILs in recovering oil in high salinity, high temperature environment.In addition, the low cost and low toxicity are more advantages to promote the use of Ionic liquids in future EOR processes.

Ionic liquids in electrokinetic chromatography