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1

Fluorescence correlation spectroscopy study on room-temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Unique fluorescence behavior was reported in room-temperature ionic liquids having imidazolium cations. Due to the molecular electronic energy level of the imidazolium cation, fluorescence in the visible range from pure ionic liquids is not expected, but was readily observed. Fluorescence correlation spectroscopy (FCS) was used to find the nature of this unique fluorescence by investigating the fluorescence fluctuation and the number density of fluorophores. FCS signal was observed in pure room-temperature ionic liquids having different cations and anions, which is considered to come from the molecular aggregate of room-temperature ionic liquid. The size and the number density of aggregates in pure ionic liquids were measured by using FCS.

Cha, Seoncheol; Kim, Doseok

2012-11-01

2

Room Temperature Ionic Liquids for Separating Organics from Produced Water  

Microsoft Academic Search

The distribution of polar organic compounds typical of water contaminants (organic acids, alcohols, and aromatic compounds) associated with oil and gas production was measured between water and nine hydrophobic, room?temperature ionic liquids. The ionic liquids used in this study were 1?butyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?hexyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?octyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?butyl?3?methylimidazolium hexafluorophosphate, trihexyltetradecylphosphonium bistrifluoromethanesulfonylimide, 1?butyl?1?methyl?pyrrolidinium bistrifluoromethanesulfonylimide, trihexyltetradecylphosphonium dodecylbenzenesulfonate, tributyltetradecylphosphonium dodecylbenzenesulfonate, and trihexyltetradecylphosphonium methanesulfonate. Sensitivity

J. McFarlane; W. B. Ridenour; H. Luo; R. D. Hunt; D. W. DePaoli; R. X. Ren

2005-01-01

3

Room temperature lithium polymer batteries based on ionic liquids  

Microsoft Academic Search

In this manuscript are reported the results of an investigation performed on rechargeable, all-solid-state, solvent-free, Li\\/LiFePO4 polymer batteries incorporating N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide, PYR14TFSI, ionic liquid (IL). The tests show clearly the beneficial effect due to the incorporation of ionic liquids on room temperature battery performance that, conversely, results extremely poor in IL-free lithium polymer batteries. The theoretical capacity is delivered at

G. B. Appetecchi; G. T. Kim; M. Montanino; F. Alessandrini; S. Passerini

2011-01-01

4

Radiation stability of some room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Radiation stability of some room temperature ionic liquids (RTILs) that find useful electrochemical applications in nuclear fuel cycle has been evaluated. The ionic liquids such as protonated betaine bis(trifluoromethylsulfonyl)imide (HbetNTf2), aliquat 336 (tri-n-octlymethylammonium chloride), 1-butyl-3-methylimidazolium chloride (bmimCl), 1-hexyl-3-methylimidazolium chloride (hmimCl), N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf2) and N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2) have been irradiated to various absorbed dose levels, up to 700 kGy. The effect of gamma radiation on these ionic liquids has been evaluated by determining the variations in the physical properties such as color, density, viscosity, refractive index and electrochemical window. The changes in density, viscosity and refractive index of these ionic liquids upon irradiation were insignificant; however, the color and electrochemical window varied significantly with increase of absorbed dose.

Jagadeeswara Rao, Ch.; Venkatesan, K. A.; Tata, B. V. R.; Nagarajan, K.; Srinivasan, T. G.; Vasudeva Rao, P. R.

2011-05-01

5

Electrodeposition of silicon nanotubes at room temperature using ionic liquid.  

PubMed

Electrodeposition inside an insulated nanoporous template using Room Temperature Ionic Liquids (RTILs) has recently been demonstrated as a promising alternative technique for synthesizing silicon nanowires due to low cost ambient growth conditions. An improvement of the method is shown here to produce Si nanotubes. A fine adjustment of electro-chemical parameters influencing ionic diffusion inside the nanopores of the template is demonstrated to preferably lead to the growth of Si nanotubes at the expense of Si nanowires. This study shows that electrodeposition in RTILs is a competitive process to grow high surface to volume ratio nanostructures at low cost and over a large scale. It also indicates a new prospect for the technique to grow and control nanostructures such as radial core-shell nanowires. PMID:23970072

Mallet, Jeremy; Martineau, Florie; Namur, Karine; Molinari, Michael

2013-08-23

6

Chromatographic and spectroscopic methods for the determination of solvent properties of room temperature ionic liquids  

Microsoft Academic Search

Room temperature ionic liquids are novel solvents with favorable environmental and technical features. Synthetic routes to over 200 room temperature ionic liquids are known but for most ionic liquids physicochemical data are generally lacking or incomplete. Chromatographic and spectroscopic methods afford suitable tools for the study of solvation properties under conditions that approximate infinite dilution. Gas–liquid chromatography is suitable for

Colin F. Poole

2004-01-01

7

Hindered intramolecular electron transfer in room-temperature ionic liquid.  

PubMed

Three perylene tetracarboxylic diimide (PDI) compounds, namely, N,N'- di(2-N'',N''-dimethylamino)ethylperylene-3,4:9,10-tetracarboxylic diimide (1), N,N'-di(2-N'',N''-dimethylamino)propylperylene-3,4:9,10-tetracarboxylic diimide (2), and N,N'- dicyclohexyl-1,7-pyrrolidinylperylene-3,4:9,10-tetracarboxylic diimide (3), have been designed and prepared. Their photophysical properties in room-temperature ionic liquid (RTILs) were studied by steady-state absorption and emission spectra and fluorescence lifetime measurements. The intramolecular photoinduced electron transfer from dimethylamine to PDI in 1 and 2 has been efficiently hindered because of the solvation of RTILs. A two-conformation mechanism for the PET in 1 and 2 is proposed, which explains the results of the fluorescence lifetime measurements well. The solvation of RTILs to 3 resembled that of a normal polar organic solvent with polarity larger than that of DMF. PMID:20377182

Wu, Haixia; Wang, Haixia; Xue, Lin; Shi, Yan; Li, Xiyou

2010-04-08

8

Abstraction of Nano Copper in a Room Temperature Ionic Liquid  

SciTech Connect

Speciation of copper in the abstraction of nano copper with a room temperature ionic liquid (RTIL) (1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6]) has been studied by X-ray absorption near edge structural (XANES) and extended X-ray absorption fine structural (EXAFS) spectroscopies in the present work. The least-square fits of the XANES spectra suggest that nano CuO (79%) and Cu(II) complex (Cu(II)-IL) (21%) are the main copper species in the RTIL. The fitted EXAFS spectra show that the Cu-O (1st shell) bond distance is 2.08 A with a coordination number (CN) of 2.6. In the second shells of copper, the average bond distance of Cu-Cu is 2.99 A with a CN of 5.1.

Peng, C. Y.; Huang, C. H. [Department of Environmental Engineering, National Cheng Kung University, Tainan City, Taiwan (China); Wang, H. Paul [Department of Environmental Engineering, National Cheng Kung University, Tainan City, Taiwan (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan City, Taiwan (China); Wei Yuling [Department of Environmental Science and Engineering, TungHai University, Taichung City, Taiwan (China)

2007-02-02

9

Fluorescence characteristics of bisphenol a in room temperature ionic liquids.  

PubMed

Room temperature ionic liquids (RTILs) are emerging as a new class of 'green' solvents for use in a wide range of chemical processes. RTILs can sensitize or quench fluorescence of organic chemicals and their interactions still remain unclear, especially for weakly fluorescent chemicals. Herein, we report the effects of six RTILs on the fluorescence behavior of bisphenol A (BPA). The fluorescence intensities (FIs) of BPA in a RTIL-acetonitrile system were significantly quenched compared to acetonitrile. The quenching effect was stronger for [CnMIM]BF4 than [CnMIM]PF6. A decreasing trend of fluorescence lifetime (FL) of BPA was observed for [C6MIM]PF6 (4.26 to 3.86 ns) and [C14MIM]PF6 (4.15 to 3.78 ns) with increasing RTIL concentrations in the range of 1-10 mM. The quenching mode was consistent with a static quenching mechanism based on the consistency of FL and FI results. The emission bands of BPA and RTILs did not interfere with each other when RTILs were used as the solvent. The investigated RTILs enhanced the FIs of strongly fluorescing chemicals (12.0?~?19.0-fold for norfloxacin and 6.1?~?8.5-fold for dansyl chloride), but quenched those of weakly fluorescing chemicals (BPA). These results demonstrate that RTILs have different fluorescent effects on organic chemicals with different fluorophores. The interactions between RTILs and BPA result from many factors in addition to viscosity, such as solvent electrostatic dielectric constant, refractive index, density, polarization and molecular interaction. These results provide a theoretical foundation for application of RTILs in the analysis of weakly fluorescing chemical. PMID:23842893

Wang, Huili; Zou, Yujie; Li, Changli; Wang, Wenwei; Zhang, Minghua; Dahlgren, Randy A; Wang, Xuedong

2013-07-11

10

Applications of room temperature ionic liquids in interfacial polymerization  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (ILs), with their unique physical and chemical properties, have been of great interest in various areas of chemical science and engineering during the last decade. In this dissertation, polyurea and polyamide films with surface nanostructures were synthesized by interfacial polymerization (IP) with ILs without stirring. Both polymers were prepared at the interface between n-hexane and a series of 1-alkyl-3-methylimidazolium ILs. Nanoporous or nanofibrous polymer morphologies with various sizes ranging from 50 to 500 nm and geometries, depending on the ILs used, were observed by scanning electron microscopy (SEM). A correlation length of ˜20nm and a suppression of three-dimensional (3-D) crystalline structure of the polyurea were found by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD), respectively. FTIR spectra showed no significant changes in the chemical composition of the polymer by the employment of ILs. The peculiar nanostructure of the polymer could be ascribed to the intermolecular interactions between the ILs and the polymer, which affected the development of the polymer morphology. The polyamides prepared with ILs showed larger intrinsic viscosities, and consequently higher molecular weights, compared to the one prepared without ILs; this could be due to the prevention of the side reaction between sebacoyl chloride and water. The enhancement of the molecular weight renders a better thermal stability to the polyamide film, as revealed by thermogravimetric analysis (TGA) which showed a higher decomposition temperature. Coating of fine particulates with polyurea by IP has been developed. With increasing stirring speed in the coating process, a decreased mean particle size and a narrower particle size distribution, as well as a lower coating weight percentage were found by particle size analysis and TGA, respectively. A Porous coating layer was formed in the IP coating in the presence of ILs. The reaction kinetics of Nylon 610 film formation with ILs were studied by measuring the product mass at different reaction times. The polymer film ceased to grow in the late stage of the reaction due to the diffusion barrier formed by the film. The characteristic time marking the cessation of the film growth was found to be dependent on the initial reactant concentrations. The evolution of the polymer molecular weight with reaction time was monitored by intrinsic viscosity measurements. It is found that the molecular weight leveled off faster than the film growth under the same reactant concentrations. Based on our experimental studies, a simplified diffusion-controlled mathematical model of IP with ILs was developed, in which the effective diffusivity in the polymer film decayed with the square of time. The model was used to fit the measured growth rate of the polymer film and the fitting results showed a conspicuously good agreement between the model and the experimental data. Physical properties of ILs relevant to the biphasic systems were also studied in this work. The interfacial tensions between organic solvents and ILs were found to decrease with ascending alkyl chain length attached to the imidazolium cations. In general, the interfacial tensions between ILs and aromatic solvents are lower than the ones with aliphatic solvents; this is attributed to the pi-pi interactions between ILs and the aromatic solvent. Self-aggregation of IL molecules in aqueous solutions and self-aggregation of ethanol in ILs are suggested based on the interfacial tension measurements. These properties are important in multi-phase chemical processes. Our study has demonstrated the potential application of ionic liquids in the interfacial polymerization of polymers with nanoscale structures.

Zhu, Lining

11

Glass Transitions and Low-Frequency Dynamics of Room-Temperature Ionic Liquids  

NASA Astrophysics Data System (ADS)

We have measured the heat capacity and neutrion quasi- and inelastic scattering spectra of some salts of 1-butyl-3-methylimidazolium ion bmim+, which is a typical cation of room-temperature ionic liquids, and its derivatives. The heat capacity measurements revealed that the room-temperature ionic liquids have glass transitions as molecular liquids. The temperature dependence of configurational entropy demonstrated that the room-temperature ionic liquids are ``fragile liquids''. Both heat capacity and inelastic neutron scattering data revealed that the glassy phases exhibit large low-energy excitations usually called ``boson peak''. The quasielastic neutron scattering data showed that so-called ``fast process'' appears around Tg as in molecular and polymer glasses. The temperature dependence of the self-diffusion coefficient derived from the neutron scattering data indicated that the orientation of bmim+ ions and/or butyl-groups of bmim+ ions is highly disordered and very flexible in an ionic liquid phase.

Yamamuro, O.; Inamura, Y.; Hayashi, S.; Hamaguchi, H.

2006-05-01

12

Potential Applications of Room Temperature Ionic Liquids for Fission Products and Actinide Separation  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) are receiving increased attention for possible applications in nuclear fuel cycle. RTILs are being investigated as possible substitutes to molecular diluents in solvent extraction, and as an alternative to high temperature molten salts in non-aqueous reprocessing applications. It is well recognized that ionic liquids often display unique extraction behavior. Unusual extraction of various metal ions

P. R. Vasudeva Rao; K. A. Venkatesan; A. Rout; T. G. Srinivasan; K. Nagarajan

2012-01-01

13

Potential Applications of Room Temperature Ionic Liquids for Fission Products and Actinide Separation  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) are receiving increased attention for possible applications in nuclear fuel cycle. RTILs are being investigated as possible substitutes to molecular diluents in solvent extraction, and as an alternative to high temperature molten salts in non-aqueous reprocessing applications. It is well recognized that ionic liquids often display unique extraction behavior. Unusual extraction of various metal ions

P. R. Vasudeva Rao; K. A. Venkatesan; Alok Rout; T. G. Srinivasan; K. Nagarajan

2011-01-01

14

60Co ?-Initiated polymerization of vinyl monomers in room temperature ionic liquid\\/THF mixed solutions  

Microsoft Academic Search

Radiation induced polymerization of styrene (St), methyl methacrylate (MMA) and n-butyl methacrylate (BMA) is carried out in a room temperature ionic liquid (RTIL), [Me3NC2H4OH]+[ZnCl3]?, and in its mixed solutions with THF. The presence of ionic liquid (IL) leads to a significant increase in monomer conversion and polymer's molecular weight. Molecular weight distribution (MWD) of resulting polymer varies with the IL

Yaodong Liu; Guozhong Wu; Dewu Long; Guorui Zhang

2005-01-01

15

Effects of Room-Temperature Ionic Liquids on Freshwater Primary Producers  

Microsoft Academic Search

Room-temperature ionic liquids (ILs) are non-volatile chemicals, which are presumed to be environmentally friendly because they pose no significant threat to air quality. However, the potential toxic effects of ILs on aquatic environments have not been studied, despite the likelihood of unintentional releases into streams and lakes during industrial applications. We studied the effects of ILs on the growth rates

K. J. Kulacki; R. J. Bernot; G. A. Lamberti; D. M. Lodge

2005-01-01

16

Morphology of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids  

Microsoft Academic Search

The structural organization in selected room temperature ionic liquids, namely (a) butyl-, (b) hexyl- and (c) octyl-3-methylimidazolium hexafluorophosphate, is investigated by means of X-ray diffraction. We find novel experimental evidences of the existence of a high degree of intermediate range order that is associated to nanoscale segregation of the alkyl chains into the charged matrix. The size of these structural

Alessandro Triolo; Olga Russina; Barbara Fazio; Roberto Triolo; Emanuela Di Cola

2008-01-01

17

Bronsted acidic room temperature ionic liquids derived from N, N-dimethylformamide and similar protophilic amides.  

SciTech Connect

We herein describe a convenient and efficient one-pot route to a new family of cost-effective, highly proton conductive room temperature ionic liquids based on N,N-dimethylformamide and structural analogues thereof, thereby opening up potential in the fuel cell industry and other areas.

Huang, Jing-Fang [ORNL; Baker, Gary A [ORNL; Luo, Huimin [ORNL; Hong, Kunlun [ORNL; Li, Qing [ORNL; Bjerrum, Neils [University of Denmark; Dai, Sheng [ORNL

2006-01-01

18

Phase Separation in Solutions of Room Temperature Ionic Liquids in Hydrocarbons  

Microsoft Academic Search

The room temperature ionic liquids (RTIL) trihexyl-tetradecyl phosphonium chloride (P666 14Cl) and the bromide (P666 14Br) are soluble in hydrocarbons. The investigated solutions in heptane, octane, nonane and decane show liquid-liquid phase separation with an upper critical solution point at ambient temperatures at molar fractions near 0.03 of the salt. Phase diagrams are reported and analysed presuming Ising criticality. The

D. Saracsan; C. Rybarsch; W. Schröer

2006-01-01

19

Fast diffusion in a room-temperature ionic liquid confined in mesoporous carbon  

SciTech Connect

We report a quasielastic neutron scattering study in the temperature range of 290 to 350 K of a room temperature ionic liquid, [bmim+][Tf2N-], in the bulk form and confined in the 8.8 2.1 nm diameter pores of a mesoporous carbon matrix. In both bulk and confined liquids, our measurements, which are sensitive to the dynamics of the hydrogen-bearing cations, detect two distinct relaxation processes related to the diffusion of the cations. We have found that the cations that do not become immobilized near the pore walls exhibit an enhanced rather than suppressed diffusivity compared to the cation diffusivity in bulk liquid. Our results provide first experimental observation of molecular diffusion in a room temperature ionic liquid in confinement which is faster than diffusion in the bulk liquid.

Mamontov, Eugene [ORNL; Wesolowski, David J [ORNL; Fulvio, Pasquale F [ORNL; Dai, Sheng [ORNL

2012-01-01

20

Lithium assisted electrochemical reduction of uranium oxide in room temperature ionic liquid  

Microsoft Academic Search

Lithium assisted electrochemical reduction of U3O8 in the room temperature ionic liquid (RTIL), N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2), was studied to explore the feasibility of using RTILs for direct electrochemical reduction of uranium oxide at near ambient\\u000a temperature. The electrochemical behavior of Li+ in MPPiNTf2 at stainless steel electrode was investigated by cyclic voltammetry and chronoamperometry. The cyclic voltammogram of LiNTf2 in

Biju Joseph; K. A. Venkatesan; K. Nagarajan; T. G. Srinivasan; P. R. Vasudeva Rao

2011-01-01

21

Decoupling charge transport from the structural dynamics in room temperature ionic liquids  

SciTech Connect

Light scattering and dielectric spectroscopy measurements were performed on the room temperature ionic liquid (RTIL) [C4mim][NTf2] in a broad temperature and frequency range. Ionic conductivity was used to estimate self-diffusion of ions, while light scattering was used to study structural relaxation. We demonstrate that the ionic diffusion decouples from the structural relaxation process as the temperature of the sample decreases toward Tg. The strength of the decoupling appears to be significantly lower than that expected for a supercooled liquid of similar fragility. The structural relaxation process in the RTIL follows well the high-temperature mode coupling theory (MCT) scenario. Using the MCT analysis we estimated the dynamic crossover temperature in [C4mim][NTf2] to be Tc 225 5 K. However, our analysis reveals no sign of the dynamic crossover in the ionic diffusion process.

Griffin, Phillip [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Agapov, Alexander L [ORNL; Kisliuk, Alexander [ORNL; Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL; Novikov, Vladimir [ORNL; Sokolov, Alexei P [ORNL

2011-01-01

22

Glass transition dynamics of room-temperature ionic liquid 1-methyl-3-trimethylsilylmethylimidazolium tetrafluoroborate.  

PubMed

The conductivity relaxation dynamics of the room-temperature ionic liquid 1-methyl-3-trimethylsilylmethylimidazolium tetrafluoroborate ([Si-MIm][BF(4)]) have been studied by broadband conductivity relaxation measurements at ambient pressure and elevated pressures up to 600 MPa. For the first time, several novel features of the dynamics have been found in a room-temperature ionic liquid. In the electric loss modulus M?(f) spectra, a resolved secondary ?-conductivity relaxation appears, and its relaxation time ?(?) shifts on applying pressure in concert with the relaxation time ?(?) of the primary ?-conductivity relaxation. The spectral dispersion of the ?-conductivity relaxation, as well as the fractional exponent (1 - n) of the Kohlrausch-Williams-Watts function that fits the spectral dispersion, is invariant to various combinations of pressure and temperature that keep ?(?) constant. Moreover, ?(?) is unchanged. Thus the three quantities, ?(?), ?(?), and n, are coinvariant to changes in pressure and temperature. This strong connection to the ?-conductivity relaxation shown by the ?-conductivity relaxation in [Si-MIm][BF(4)] indicates that it is the analogue of the Johari-Goldstein ?-relaxation in nonionically conducting glass-formers. The findings have fundamental implications on theoretical interpretation of the conductivity relaxation processes and glass transition in ionic liquids. It is also the first time such a secondary conductivity relaxation or the primitive conductivity relaxation of the coupling model has been fully resolved and identified in M?(f) in any ionically conducting material that we know of. PMID:21950493

Jarosz, Georgina; Mierzwa, Michal; Zio?o, Jerzy; Paluch, Marian; Shirota, Hideaki; Ngai, K L

2011-10-17

23

Supported Room Temperature Ionic Liquid Membranes for CO{sub 2}/CH{sub 4} Separation  

SciTech Connect

Room temperature ionic liquids (RTILs) are organic salts which are liquid at or around room temperature. These compounds exhibit many outstanding physical properties such as great thermal stability and no measurable vapor pressure. In this work supported ionic liquid membranes (SILMs) were prepared by impregnating pores of ?-alumina inorganic supports with various ionic liquids. In addition to membranes prepared with pure RTILs we were able to synthesize membranes with RTIL mixtures using 1-aminopyridinium iodide dissolved in 1-butyl-4-methylpyridinium tetrafluoroborate or methyltrioctylammonium bis(trifluoromethylsulfonyl)imide. This combination of an RTIL with an organic salt containing an amine group dramatically improved the membrane separation properties. The SILMs displayed CO{sub 2} permeance on the order of 5 × 10{sup ?10} to 5 × 10{sup ?9} mol m{sup ?2} s{sup ?1} Pa{sup ?1} combined with CO{sub 2}/CH{sub 4} selectivity of 5–30. Although these values are comparable with the current systems for CO{sub 2} purification, CO{sub 2} permeance is still rather low for these compounds.

Iarikov, D. D.; Hacarlioglu, P.; Oyama, S. T.

2011-01-01

24

Reversible swelling of the cell wall of poplar biomass by ionic liquid at room temperature  

PubMed Central

Time-resolved autofluorescence, Raman microspectroscopy, and scanning microprobe X-ray diffraction were combined in order to characterize lignocellulosic biomass from poplar trees and how it changes during treatment with the ionic liquid 1-n-ethyl-3-methylimidazolium acetate (EMIMAC) at room temperature. The EMIMAC penetrates the cell wall from the lumen, swelling the cell wall by about a factor of two towards the empty lumen. However, the middle lamella remains unchanged, preventing the cell wall from swelling outwards. During this swelling, most of the cellulose microfibrils are solubi-lized but chain migration is restricted and a small percentage of microfibrils persist. When the EMIMAC is expelled, the cellulose recrystallizes as microfibrils of cellulose I. There is little change in the relative chemical composition of the cell wall after treatment. The action of EMIMAC on the poplar cell wall at room temperature would therefore appear to be a reversible swelling and a reversible decrystallization of the cell wall.

Lucas, Marcel; Wagner, Greg L.; Nishiyama, Yoshiharu; Hanson, Leif; Samayam, Indira P.; Schall, Constance A.; Langan, Paul; Rector, Kirk D.

2012-01-01

25

Benzyl-Functionalized Room Temperature Ionic Liquids for CO2/N2 Separation  

SciTech Connect

In this work, three classes of room temperature ionic liquids (RTILs), including imidazolium, pyridinium, and pyrrolidinium ionic liquids with a benzyl group appended to the cation, were synthesized and tested for their performance in separating CO{sub 2} and N{sub 2}. All RTILs contained the bis(trifluoromethylsulfonyl)imide anion, permitting us to distinguish the impact of the benzyl moiety attached to the cation on gas separation performance. In general, the attachment of the benzyl group increased the viscosity of the ionic liquid compared with the unfunctionalized analogs and decreased the CO{sub 2} permeability. However, all of the benzyl-modified ionic liquids exhibited enhanced CO{sub 2}/N{sub 2} selectivities compared with alkyl-based ionic liquids, with values ranging from 22.0 to 33.1. In addition, CO{sub 2} solubilities in the form of Henry's constants were also measured and compared with unfunctionalized analogs. Results of the membrane performance tests and CO{sub 2} solubility measurements demonstrate that the benzyl-functionalized RTILs have significant potential for use in the separation of carbon dioxide from combustion products.

Mahurin, Shannon Mark [ORNL; Dai, Thomas N [ORNL; Yeary, Joshua S [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL

2011-01-01

26

Scanning Electron Microscope Observation of Nano Carbon Materials with Imidazolium-Type Room Temperature Ionic Liquids  

NASA Astrophysics Data System (ADS)

A novel pre-treatment method for scanning electron microscopy (SEM) observation using room temperature ionic liquids (ILs) was used for several carbon nano materials. After the ILs pre-treatment, the quality of the SEM images obtained was almost the same as that obtained with conventional platinum/palladium (Pt/Pd) spattering pre-treatment. The highest resolution in this study was under 30 nm. This result means that the pre-treatment with IL can form ultrathin layer on the sample surface at several molecules level. Therefore, the ILs pre-treatment is a simple and easy tool for SEM observation of nano materials on insulating substrates.

Abe, Shigeaki; Hyono, Atsushi; Nakayama, Katsutoshi; Takada, Tomoya; Yonezawa, Tetsu

2013-01-01

27

Solvent extraction and extraction-voltammetric determination of phenols using room temperature ionic liquid.  

PubMed

The phenolic compounds phenol, 4-nitrophenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 1-naphthol, 2-naphthol, and 4-chlorophenol are extracted nearly quantitatively from aqueous solution into the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) in molecular form at pH < p Ka. Picric acid is extracted efficiently in anionic form. Recovery of pyrocatechol and resorcinol is much lower. The effect of pH, phenol concentration, and volume ratio of aqueous and organic phases were studied. Ionic liquid BMImPF6 is shown to be suitable for extraction-voltammetric determination of phenols without back-extraction or addition of support electrolyte. The electrochemical window of BMImPF6 at various electrodes was determined, and voltammetric oxidation of phenols and reduction of nitrophenols in BMImPF6 was studied. PMID:15578163

Khachatryan, Kristine S; Smirnova, Svetlana V; Torocheshnikova, Irina I; Shvedene, Natalia V; Formanovsky, Andrey A; Pletnev, Igor V

2004-12-02

28

Electrodeposition of aluminium and aluminium\\/platinum alloys from AlCl 3 \\/benzyltrimethylammonium chloride room temperature ionic liquids  

Microsoft Academic Search

This paper shows that aluminium and aluminium\\/platinum alloys can be deposited from room temperature ionic liquids formed from an adduct of aluminium trichloride with benzyltrimethyl ammonium chloride. The advantages of this ionic liquid over the majority of those previously investigated is that it is less water sensitive, easier to purify and form and significantly more cost effective. Voltammetry and chronoamperometry

Andrew P. Abbott; Christopher A. Eardley; Nicola R. S. Farley; Gerald A. Griffith; Allin Pratt

2001-01-01

29

Mechanisms of metal ion transfer into room-temperature ionic liquids : the role of anion exchange.  

SciTech Connect

The structure and stoichiometry of the lanthanide(III) (Ln) complexes with the ligand 2-thenoyltrifluoroacetone (Htta) formed in a biphasic aqueous room-temperature ionic liquid system have been studied by complementary physicochemical methods. Equilibrium thermodynamics, optical absorption and luminescence spectroscopies, high-energy X-ray scattering, EXAFS, and molecular dynamics simulations all support the formation of anionic Nd(tta){sub 4}{sup -} or Eu(tta){sub 4}{sup -} complexes with no water coordinated to the metal center in 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C{sub 4}mim{sup +}Tf{sub 2}N{sup -}), rather than the hydrated, neutral complexes, M(tta){sub 3}(H{sub 2}O){sub n} (n = 2 or 3), that form in nonpolar molecular solvents, such as xylene or chloroform. The presence of anionic lanthanide complexes in C{sub 4}mim{sup +}Tf{sub 2}N{sup -} is made possible by the exchange of the ionic liquid anions into the aqueous phase for the lanthanide complex. The resulting complexes in the ionic liquid phase should be thought of as weak C{sub 4}mim{sup +}Ln(tta){sub 4}{sup -} ion pairs which exert little influence on the structure of the ionic liquid phase.

Jensen, M. P.; Neuefeind, J.; Beitz, J. V.; Skanthakumar, S.; Soderholm, L.; Chemistry

2003-12-17

30

Fission-Product Separation Based on Room-Temperature Ionic-Liquids  

SciTech Connect

During the previous funding cycle for this project, we investigated the electrochemistry of Cs(I) in air and moisture-stable ionic liquids both with and without the addition of BOBCalixC6. These investigations revealed that the electrochemical windows of the dialkylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquids do not permit the direct electrochemical reduction of Cs(I), even when Hg electrodes are employed, because these organic cations are reduced at less negative potentials than Cs(I). However, Cs(I) coordinated by BOBCalixC6 can be electrolytically reduced to Cs(Hg) in tetraalkylammonium-based room-temperature ionic liquids such as tri-1-butylmethylammonium bis[(trifluoromethyl)sulfonyl]imide (Bu3MeN+Tf2N-) at Hg electrodes. Because this reduction process does not harm either the ionic liquid or the macrocycle, it is a promising method for recycling the cesium extraction system. The previous studies mentioned above were carried out under an inert atmosphere, i.e., in the absence of H2O and O2. However, it may not be economically feasible or even possible to carry out the recycling process in the absence of these contaminants during large-scale processing of aqueous tank waste. Thus, as described in our proposal, we have begun an investigation of the electrochemical recovery of Cs from the Bu3MeN+Tf2N- + BOBCalixC6 extraction system in an air atmosphere containing various amounts of water and oxygen. Our recent preliminary results were very surprising because they indicated that the electrochemical extraction process is relatively insensitive to the presence of small amounts of moisture even when the moisture content of the ionic liquid approaches 1000 ppm. Furthermore, we have found that the ''wet'' ionic liquid can be easily dehydrated under reduced pressure or by sparging with dry nitrogen gas without the need for heat or any other specialized treatment.

Hussey, Charles L.

2005-06-01

31

Changed reactivity of the 1-bromo-4-nitrobenzene radical anion in a room temperature ionic liquid.  

PubMed

Radical anions of 1-bromo-4-nitrobenzene (p-BrC6H4NO2) are shown to be reactive in the room temperature ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, ([C4mPyrr][NTf2]), by means of voltammetric measurements. In particular, they are shown to react via a DISP type mechanism such that the electrolysis of p-BrC6H4NO2 occurs consuming between one and two electrons per reactant molecule, leading to the formation of the nitrobenzene radical anion and bromide ions. This behaviour is a stark contrast to that in conventional non-aqueous solvents such as acetonitrile, dimethyl sulfoxide or N,N-dimethylformamide, which suggests that the ionic solvent promotes the reactivity of the radical anion, probably via stabilisation of the charged products. PMID:23525257

Ernst, Sven; Ward, Kristopher R; Norman, Sarah E; Hardacre, Christopher; Compton, Richard G

2013-05-01

32

Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids  

SciTech Connect

Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf2], [bmim][PF6], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward Tg. The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10 11 s up to 102 s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature.We suggest that these phenomena are interconnected and all result from the same underlying mechanism strong and directional intermolecular interactions.

Griffin, Phillip [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Agapov, Alexander L [ORNL; Sokolov, Alexei P [ORNL

2012-01-01

33

Layered structure of room-temperature ionic liquids in microemulsions by multinuclear NMR spectroscopic studies.  

PubMed

Microemulsions form in mixtures of polar, nonpolar, and amphiphilic molecules. Typical microemulsions employ water as the polar phase. However, microemulsions can form with a polar phase other than water, which hold promise to diversify the range of properties, and hence utility, of microemulsions. Here microemulsions formed by using a room-temperature ionic liquid (RTIL) as the polar phase were created and characterized by using multinuclear NMR spectroscopy. (1)H, (11)B, and (19)F?NMR spectroscopy was applied to explore differences between microemulsions formed by using 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) as the polar phase with a cationic surfactant, benzylhexadecyldimethylammonium chloride (BHDC), and a nonionic surfactant, Triton X-100 (TX-100). NMR spectroscopy showed distinct differences in the behavior of the RTIL as the charge of the surfactant head group varies in the different microemulsion environments. Minor changes in the chemical shifts were observed for [bmim](+) and [BF(4)](-) in the presence of TX-100 suggesting that the surfactant and the ionic liquid are separated in the microemulsion. The large changes in spectroscopic parameters observed are consistent with microstructure formation with layering of [bmim](+) and [BF(4)](-) and migration of Cl(-) within the BHDC microemulsions. Comparisons with NMR results for related ionic compounds in organic and aqueous environments as well as literature studies assisted the development of a simple organizational model for these microstructures. PMID:21547960

Falcone, R Dario; Baruah, Bharat; Gaidamauskas, Ernestas; Rithner, Christopher D; Correa, N Mariano; Silber, Juana J; Crans, Debbie C; Levinger, Nancy E

2011-05-06

34

Existence of optical phonons in the room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate  

PubMed Central

The technologically important properties of room temperature ionic liquids (RTILs) are fundamentally linked to the ion–ion interactions present among the constituent ions. These ion–ion interactions in one RTIL (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, [C2mim]CF3SO3) are characterized with transmission FTIR spectroscopy and polarized attenuated total reflection (ATR) FTIR spectroscopy. A quasilattice model is determined to be the best framework for understanding the ionic interactions. A novel spectroscopic approach is proposed to characterize the degree of order that is present in the quasilattice by comparing the dipole moment derivative calculated from two independent spectroscopic measurements: (1) the TO–LO splitting of a vibrational mode using dipolar coupling theory and (2) the optical constants of the material derived from polarized ATR experiments. In principle, dipole moment derivatives calculated from dipolar coupling theory should be similar to those calculated from the optical constants if the quasilattice of the RTIL is highly structured. However, a significant disparity for the two calculations is noted for [C2mim]CF3SO3, indicating that the quasilattice of [C2mim]CF3SO3 is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ion–ion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL.

Burba, Christopher M.; Frech, Roger

2011-01-01

35

Free Radical Polymerization of Styrene and Methyl Methacrylate in Various Room Temperature Ionic Liquids  

SciTech Connect

Conventional free radical polymerization of styrene and methyl methacrylate was carried out in various room temperature ionic liquids (RTILs). The RTILs used in this research encompass a wide range of cations and anions. Typical cations include imidazolium, phosphonium, pyridinium, and pyrrolidinium; typical anions include amide, borate, chloride, imide, phosphate, and phosphinate. Reactions are faster and polymers obtained usually have higher molecular weights when compared to polymerizations carried out in volatile organic solvents under the same conditions. This shows that rapid rates of polymerization and high molecular weights are general features of conventional radical polymerizations in RTILs. Attempts to correlate the polarities and viscosities of the RTILs with the polymerization behavior fail to yield discernible trends.

Zhang, Hongwei [University of Tennessee, Knoxville (UTK); Hong, Kunlun [ORNL; Mays, Jimmy [ORNL

2005-01-01

36

The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate: Electrochemical couples and physical properties  

SciTech Connect

Room temperature molten salts composed of the 1-ethyl-3-methylimidazolium cation and a chloroaluminate anion have received much attention for use in a variety of commercial applications such as batteries, photovoltaics, metal deposition, and capacitors. The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF{sub 4}) was demonstrated as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion reduction. Square-wave voltammetric data for ferrocene oxidation were fit to a reversible one-electron process using the COOL algorithm to give a half-wave potential of 0.490 V vs. Al/Al(III) and a diffusion coefficient of 5.1 {times} 10{sup {minus}7} cm{sup 2}/s. The two-electron oxidation of tetrathiafulvalene was reversible and proceeded through two consecutive one-electron steps; although data collected at lower square-wave frequencies indicated a slow precipitation of the TTF{sup +} species. Lithium ion was reduced to lithium metal at a Pt electrode following the addition of water to the EMIBF{sub 4} electrolyte, whereas lithium ion reduction at an Al wire produced the {beta}-LiAl alloy. Conductivities and kinematic viscosities of EMIBF{sub 4} were measured from 20 to 100 C and had values of 14 mS/cm and 0.275 cm{sup 2}/s, respectively, at 25 C.

Fuller, J.; Carlin, R.T.; Osteryoung, R.A. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemistry

1997-11-01

37

Solvent extraction of amino acids into a room temperature ionic liquid with dicyclohexano-18-crown-6.  

PubMed

Amino acids Trp, Gly, Ala, Leu are extracted efficiently from aqueous solution at pH 1.5-4.0 (Lys and Arg at pH 1.5-5.5) into the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF(6)) with dicyclohexano-18-crown-6 (CE). The most hydrophilic amino acids such as Gly are extracted as efficiently as the less hydrophilic (92-96%). The influence of pH, amino acid and crown ether concentration, volume ratio of aqueous and organic phases, and presence of some cations on amino acid recovery were studied. The ratio of amino acid to crown ether in the extracted species is 1:1 for cationic Trp, Leu, Ala, and Gly and to 1:2 for dicationic Arg and Lys. This ionic liquid extraction system was used successfully for the recovery of amino acids from pharmaceutical samples and fermentation broth, and was followed by fluorimetric determination. PMID:14747900

Smirnova, Svetlana V; Torocheshnikova, Irina I; Formanovsky, Andrey A; Pletnev, Igor V

2004-01-28

38

Ionic liquid pretreatment of poplar wood at room temperature: swelling and incorporation of nanoparticles  

SciTech Connect

Lignocellulosic biomass represents a potentially sustainable source of liquid fuels and commodity chemicals. It could satisfy the energy needs for transportation and electricity generation, while contributing substantially to carbon sequestration and limiting the accumulation of greenhouse gases in the atmosphere. Potential feedstocks are abundant and include crops, agricultural wastes, forest products, grasses, and algae. Among those feedstocks, wood is mainly constituted of three components: cellulose, hemicellulose, and lignin. The conversion process of lignocellulosic biomass typically consists of three steps: (1) pretreatment; (2) hydrolysis of cellulose and hemicellulose into fermentable sugars; and (3) fermentation of the sugars into liquid fuels (ethanol) and other commodity chemicals. The pretreatment step is necessary due to the complex structure of the plant cell wall and the chemical resistance of lignin. Most current pretreatments are energy-intensive and/or polluting. So it is imperative to develop new pretreatments that are economically viable and environmentally friendly. Recently, ionic liquids have attracted considerable interest, due to their ability to dissolve biopolymers, such as cellulose, lignin, native switchgrass, and others. Ionic liquids are also considered green solvents, since they have been successfully recycled at high yields for further use with limited efficiency loss. Also, a few microbial cellulases remain active at high ionic liquid concentration. However, all studies on the dissolution of wood in ionic liquids have been conducted so far at high temperatures, typically above 90 C. Development of alternative pretreatments at room temperature is desirable to eliminate the additional energy cost. In this study, thin sections of poplar wood were swollen at room temperature by a 3 h ionic liquid (1-ethyl-3-methylimidazolium acetate or EMIMAc) pretreatment. The pretreated sample was then exposed to an aqueous suspension of nanoparticles that resulted in the sample contraction and the deposition of nanoparticles onto the surface and embedded into the cell wall. To date, both silver and gold particles ranging in size from 40-100 nm have been incorporated into wood. Penetration of gold nanoparticles of 100 nm diameter in the cell walls was best confirmed by near-infrared confocal Raman microscopy, since the deposition of gold nanoparticles induces a significant enhancement of the Raman signal from the wood in their close proximity, an enhancement attributed to the surface-enhanced Raman effect (SERS). After rinsing with water, scanning electron microscopy (SEM) and Raman images of the same areas show that most nanoparticles remained on the pretreated sample. Raman images at different depths reveal that a significant number of nanoparticles were incorporated into the wood sample, at depths up to 4 {micro}m, or 40 times the diameter of the nanoparticles. Control experiments on an untreated wood sample resulted in the deposition of nanoparticles only at the surface and most nanoparticles were removed upon rinsing. This particle incorporation process enables the development of new pretreatments, since the nanoparticles have a high surface-to-volume ratio and could be chemically functionalized. Other potential applications for the incorporated nanoparticles include isotope tracing, catalysis, imaging agents, drug-delivery systems, energy-storage devices, and chemical sensors.

Lucas, Marcel [Los Alamos National Laboratory; Macdonald, Brian A [Los Alamos National Laboratory; Wagner, Gregory L [Los Alamos National Laboratory; Joyce, Steven A [Los Alamos National Laboratory; Rector, Kirk D [Los Alamos National Laboratory

2010-01-01

39

A novel one step synthesis of silver nanoparticles using room temperature ionic liquid and their biocidal activity  

Microsoft Academic Search

This article reports the synthesis of silver Nan particles (SNPs) using 1-(dodecyl) 2 amino-pyridinium bromide ionic liquid. This is a new one phase method for the synthesis of uniform monodispersed crystalline silver nanoparticles in a water-ionic liquid system. In this work, the functionalized room temperature IL acts as stabilizing agent and solvent. Hydrazine hydrate acts as reducing agent. To the

R. S. Patil; M. R. Kokate; P. P. Salvi; S. S. Kolekar

40

Kinetics and Thermodynamics of Hydrogen Oxidation and Oxygen Reduction in Hydrophobic Room-Temperature Ionic Liquids  

PubMed Central

In this study 1-dodecyl-3-methylimidazolium (C12mim) bis(pentafluoroethylsulfonyl)imide (BETI) and 1-dodecylimidazolium (C12im) BETI hydrophobic room-temperature ionic liquids (RTILs) were synthesized and used as proton-conducting electrolytes in a nonhumidified feed gas electrochemical cell. The ionic conductivities of C12mimBETI and C12imBETI were similar and increased linearly with an increase in temperature from 20 to 130°C. However, when used in the electrochemical system the protic water-equilibrated C12imBETI had a larger maximum current and power density compared to the aprotic water-equilibrated C12mimBETI. The effect of water content on the reaction rates and thermodynamics of these hydrophobic RTILs was also examined. The efficiency of the C12mimBETI increased upon removal of water while that of the C12imBETI decreased in efficiency when water was removed. The water structure in these RTILs was examined using attenuated total internal reflection Fourier transform IR spectroscopy and depended on the chemical structure of the cation. These studies give further insight into the possible mechanism of proton transport in these RTIL systems.

Rollins, Julie B.; Conboy, John C.

2010-01-01

41

Supported Phospholipid Bilayer Defects Created by a Cation or Anion of a Room-Temperature Ionic Liquid  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this work, the independent effects on a supported phospholipid bilayer (SPB) caused by a cation and anion of a room-temperature ionic liquid (RT-IL) were studied via atomic force microscopy (AFM). The supported phospholipid bilayer was composed only of 1,2-dielaidoylphosphatidylcholine (DEPC) an...

42

Synthesis and characterization of luminescent room temperature ionic liquids based on Ru(bpy)(CN)(4)(2-).  

PubMed

Novel ammonium and phosphonium room temperature ionic liquids based on Ru(bpy)(CN)4 as a luminescent complex anion have been developed and characterized by comparative absorption, emission, NMR and electrochemical studies as well as the evaluation of their polarity behaviour. PMID:23303479

Gago, Sandra; Cabrita, Luis; Lima, J Carlos; Branco, Luis C; Pina, Fernando

2013-01-09

43

Poly(ethylene oxide)-based polymer electrolyte incorporating room-temperature ionic liquid for lithium batteries  

Microsoft Academic Search

The effect of incorporating a room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI), in the polymer electrolyte (PE) based on poly(ethylene oxide)-(lithium bis(trifluoromethanesulfonyl) imide) [PEO-LiTFSI] was investigated. BMITFSI content was varied between 20 and 80 parts by weight (pbw) in 100 pbw of PEO-LiTFSI and the influence on ionic conductivity, electrochemical stability and interfacial properties on lithium electrode was studied. A remarkable

Jae-Won Choi; Gouri Cheruvally; Yeon-Hwa Kim; Jae-Kwang Kim; James Manuel; Prasanth Raghavan; Jou-Hyeon Ahn; Ki-Won Kim; Hyo-Jun Ahn; Doo Seong Choi; Choong Eui Song

2007-01-01

44

On the diffusion of ferrocenemethanol in room-temperature ionic liquids: an electrochemical study.  

PubMed

The electrochemical behaviour of ferrocenemethanol (FcMeOH) has been studied in a range of room-temperature ionic liquids (RTILs) using cyclic voltammetry, chronoamperomery and scanning electrochemical microscopy (SECM). The diffusion coefficient of FcMeOH, measured using chronoamperometry, decreased with increasing RTIL viscosity. Analysis of the mass transport properties of the RTILs revealed that the Stokes-Einstein equation did not apply to our data. The "correlation length" was estimated from diffusion coefficient data and corresponded well to the average size of holes (voids) in the liquid, suggesting that a model in which the diffusing species jumps between holes in the liquid is appropriate in these liquids. Cyclic voltammetry at ultramicroelectrodes demonstrated that the ability to record steady-state voltammograms during ferrocenemethanol oxidation depended on the voltammetric scan rate, the electrode dimensions and the RTIL viscosity. Similarly, the ability to record steady-state SECM feedback approach curves depended on the RTIL viscosity, the SECM tip radius and the tip approach speed. Using 1.3 ?m Pt SECM tips, steady-state SECM feedback approach curves were obtained in RTILs, provided that the tip approach speed was low enough to maintain steady-state diffusion at the SECM tip. In the case where tip-induced convection contributed significantly to the SECM tip current, this effect could be accounted for theoretically using mass transport equations that include diffusive and convective terms. Finally, the rate of heterogeneous electron transfer across the electrode/RTIL interface during ferrocenemethanol oxidation was estimated using SECM, and k(0) was at least 0.1 cm s(-1) in one of the least viscous RTILs studied. PMID:21526252

Lovelock, Kevin R J; Ejigu, Andinet; Loh, Sook Fun; Men, Shuang; Licence, Peter; Walsh, Darren A

2011-04-28

45

Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids.  

PubMed

This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) at 40 degrees C and low pressures (approximately 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % [C2mim][BF4] in [C2mim][Tf2N]. Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO2 with N2 or CH4 in pure [C2mim][BF4] can be enhanced by adding 5 mol % [C2mim][Tf2N]. PMID:18247501

Finotello, Alexia; Bara, Jason E; Narayan, Suguna; Camper, Dean; Noble, Richard D

2008-02-02

46

Nonionic surfactant mixtures in an imidazolium-type room-temperature ionic liquid.  

PubMed

The physicochemical properties of nonionic surfactant mixtures in an aprotic, imidazolium-type room-temperature ionic liquid (RT-IL) have been studied using a combination of static surface tensiometry, dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). The surfactants used in this study are phytosterol ethoxylates (BPS-n, where n is an oxyethylene chain length of either 5 or 30) and the selected RT-IL is 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF(6)). The shorter chain oxyethylene surfactant (BPS-5) exhibits greater surface activity in BmimPF(6) than BPS-30; hence, BPS-5 is a major component in driving the interfacial adsorption and molecular aggregation of the mixed system. The surface tension data demonstrate that an increased mole fraction of BPS-5 results in a decreased critical aggregation concentration (cac) and negatively increased Gibbs free energies estimated for molecular aggregation (?G(0)(agg)) and interfacial adsorption (?G(0)(ads)). Indeed, the compositions of the monolayer adsorbed at the air/solution interface and the molecular aggregate formed in the bulk solution are enriched with BPS-5. The combination of the DLS and cryo-TEM results demonstrates the spontaneous formation of multi-lamellar vesicles resulting from the BPS-5-rich composition of the molecular aggregates. PMID:22027021

Sakai, Hideki; Saitoh, Takanori; Misono, Takeshi; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko

2011-01-01

47

Electroless deposition of platinum nanoparticles in room-temperature ionic liquids.  

PubMed

The electroless deposition of Pt nanoparticles (Pt-NPs) could be carried out by dissolving potassium tetrachloroplatinate(II) (K2[PtCl4]) in 1-ethyl-3-methylimidazolium (EMI(+)) room-temperature ionic liquids (RTILs) containing bis(trifluoromethylsulfonyl) imide (NTf2(-)) or tetrafluoroborate (BF4(-)) anion and small cations, such as H(+), K(+), and Li(+). In this case, no deposition of Pt-NPs occurred in RTILs without such small cations. The formation of Pt-NPs was only observed in RTILs containing trifluoromethanesulfonimide (HNTf2) and protons at high temperature (?80 °C) when potassium hexachloroplatinate(IV) (K2[PtCl6]) was dissolved in the RTILs. The obtained Pt-NPs gave a characteristic absorption spectrum of ultrasmall Pt-NPs. The ultrasmall and uniform Pt-NPs of ca. 1-4 nm in diameter were produced and the Pt-NPs/EMI(+)NTf2(-) dispersion was kept stably for several months without adding any additional stabilizers or capping molecules. The identified Fourier-transform patterns along the [0 1 1] zone axis were observed for the TEM images of Pt-NPs. On the basis of the results obtained, a probable mechanism of the electroless formation of Pt-NPs is discussed. PMID:23985068

Zhang, Da; Okajima, Takeyoshi; Lu, Dalin; Ohsaka, Takeo

2013-09-13

48

Effects of Room-Temperature Ionic Liquids on Zebra Mussels (Dreissena polymorpha)  

NASA Astrophysics Data System (ADS)

Zebra mussels (Dreissena polymorpha) are exotic bivalves that are widely distributed in eastern North America. We propose that this nuisance organism could serve as a model species for studies of aquatic toxicology. We tested zebra mussels response to room-temperature ionic liquids (ILs), which are being synthesized as environmentally friendly alternatives to volatile organic solvents. Volatile organic solvents contribute to atmospheric pollution and ozone depletion, whereas ILs are non-volatile and less harmful to the atmosphere. Although ILs would contribute significantly less to air pollution, little is known about their potential effects on aquatic ecosystems. In 72-hour toxicity tests, we determined the acute effects of three imidazolium-based ILs (1-butyl-3-methylimidazolium bromide (bmimBr), 1-hexyl-3-methylimidazolium bromide (hmimBr), and 1-octyl-3-methylimidazolium bromide (omimBr)) on the survival of zebra mussels. As alkyl chain length decreased, median lethal concentration (LC50) decreased from 1291 mg L-1 for bmimBr, to 105 mg L-1 for hmimBr, and 21.2 mg L-1 for omimBr. For bivalve mussels, the toxicities of these ILs are comparable to the toxicities of commonly used industrial solvents (e.g., toluene, benzene). This study presents a foundation for using zebra mussels in toxicity studies as well as possible models for less common Unionid mussels.

Costello, D. M.; Bernot, R. J.; Lamberti, G. A.

2005-05-01

49

Hydrogen-bonding interactions and protic equilibria in room-temperature ionic liquids containing crown ethers.  

SciTech Connect

Nuclear magnetic resonance (NMR) spectroscopy has been used to study hydrogen-bonding interactions between water, associated and dissociated acids (i.e., nitric and methanesulfonic acids), and the constituent ions of several water-immiscible room-temperature ionic liquids (ILs). In chloroform solutions also containing a crown ether (CE), water molecules strongly associate with the IL ions, and there is rapid proton exchange between these bound water molecules and hydronium associated with the CE. In neat ILs, the acids form clusters differing in their degree of association and ionization, and their interactions with the CEs are weak. The CE can either promote proton exchange between different clusters in IL solution when their association is weak or inhibit such exchange when the association is strong. Even strongly hydrophobic ILs are shown to readily extract nitric acid from aqueous solution, typically via the formation of a 1:1:1 {l_brace}H{sub 3}O{sup +} {center_dot} CE{r_brace}NO{sub 3}{sup -} complex. In contrast, the extraction of methanesulfonic acid is less extensive and proceeds mainly by IL cation-hydronium ion exchange. The relationship of these protic equilibria to the practical application of hydrophobic ILs (e.g., in spent nuclear fuel reprocessing) is discussed.

Marin, T.; Shkrob, I.; Dietz, M. (Chemical Sciences and Engineering Division); (Benedictine Univ.); (Univ. of Wisconsin at Milwaukee)

2011-04-14

50

Islands of CdSe nanoparticles within Se nanofibers: a room temperature ionic liquid templated synthesis.  

PubMed

Herein, we present the formation of cadmium selenide (CdSe) islands embedded in a porous structure of entangled selenium (Se) nanofibers in the host matrix of a room temperature ionic liquid (RTIL). Electron beam irradiation has been employed to initiate the formation of the nanostructure while RTIL simultaneously played the role of a solvent, stabilizer and a shape guiding template for such morphology. UV-Vis absorption spectra of the irradiated samples exhibited an excitonic absorption feature in the visible region. The as-obtained nanostructure was characterized by TEM, SEM, XRD and EDX studies. Raman spectroscopic analysis of as-grown nanomaterials provided significant information about the formation of CdSe as well as distinct features of different forms of Se which further substantiated the results obtained from the above mentioned studies. Interestingly, an equivalent dose of ?-radiation led to the formation of predominantly nanosheet like structures in conjunction with a relatively homogeneous distribution of CdSe nanoparticles in the same matrix. The possible mechanism behind the obtained structures in these two methods has been proposed, and was rationalized in terms of dose rate difference and the existence of inherent heterogeneity in the structure of the IL. Finally, the implications of such a structure in various fields such as catalysis, sensing and photovoltaics have been discussed. PMID:24005564

Guleria, Apurav; Singh, Ajay K; Rath, Madhab C; Adhikari, Soumyakanti; Sarkar, Sisir K

2013-09-04

51

Effects of Room-Temperature Ionic Liquids on Freshwater Primary Producers  

NASA Astrophysics Data System (ADS)

Room-temperature ionic liquids (ILs) are non-volatile chemicals, which are presumed to be environmentally friendly because they pose no significant threat to air quality. However, the potential toxic effects of ILs on aquatic environments have not been studied, despite the likelihood of unintentional releases into streams and lakes during industrial applications. We studied the effects of ILs on the growth rates of the freshwater green algae Scenedesmus quadricauda and Chlamydomonas reinhardtii in 96-h bioassays. ILs with increasing alkyl chain lengths (from 1-butyl- to 1-hexyl- to 1-octyl-3-methylimidazolium bromide) were increasingly toxic to S. quadricauda (EC-50 values of 0.28 mg*L-1, 0.04 mg*L-1, and <0.005 mg*L-1 respectively). S. quadricauda growth rates decreased with increasing IL concentration across all treatments. Compared to controls, C. reinhardtii growth rates were higher at 200-800 mg*L-1 1-butyl-3-methylimidazolium bromide (bmimBr) treatments, but declined at 1600 mg*L-1 bmimBr. These results illustrate that different algal taxa can respond quite differently to potential chemical pollutants. Furthermore, by studying the effects of ILs on primary producers in concert with organisms from other trophic levels, we can develop hypotheses about how these effects may be felt throughout aquatic ecosystems.

Kulacki, K. J.; Bernot, R. J.; Lamberti, G. A.; Lodge, D. M.

2005-05-01

52

Cloud point phenomena for POE-type nonionic surfactants in a model room temperature ionic liquid.  

PubMed

The cloud point phenomenon has been investigated for the solutions of polyoxyethylene (POE)-type nonionic surfactants (C(12)E(5), C(12)E(6), C(12)E(7), C(10)E(6), and C(14)E(6)) in 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), a typical room temperature ionic liquid (RTIL). The cloud point, T(c), increases with the elongation of the POE chain, while decreases with the increase in the hydrocarbon chain length. This demonstrates that the solvophilicity/solvophobicity of the surfactants in RTIL comes from POE chain/hydrocarbon chain. When compared with an aqueous system, the chain length dependence of T(c) is larger for the RTIL system regarding both POE and hydrocarbon chains; in particular, hydrocarbon chain length affects T(c) much more strongly in the RTIL system than in equivalent aqueous systems. In a similar fashion to the much-studied aqueous systems, the micellar growth is also observed in this RTIL solvent as the temperature approaches T(c). The cloud point curves have been analyzed using a Flory-Huggins-type model based on phase separation in polymer solutions. PMID:18656889

Inoue, Tohru; Misono, Takeshi

2008-04-26

53

Fission-Product Separation Based on Room-Temperature Ionic Liquids  

SciTech Connect

The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

Luo, Huimin

2006-11-15

54

Fission-Product Separation Based on Room-Temperature Ionic Liquids  

SciTech Connect

The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

Luo, Huimin; Hussey, Charles L.

2005-09-30

55

Dispersion interactions in room-temperature ionic liquids: results from a non-empirical density functional.  

PubMed

The role of dispersion or van de Waals (VDW) interactions in imidazolium-based room-temperature ionic liquids is studied within the framework of density functional theory, using a recently developed non-empirical functional [M. Dion, H. Rydberg, E. Schro?der, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)], as efficiently implemented in the SIESTA code [G. Roma?n-Pe?rez and J. M. Soler, Phys. Rev. Lett. 103, 096102 (2009)]. We present results for the equilibrium structure and lattice parameters of several crystalline phases, finding a general improvement with respect to both the local density (LDA) and the generalized gradient approximations (GGA). Similar to other systems characterized by VDW bonding, such as rare gas and benzene dimers as well as solid argon, equilibrium distances and volumes are consistently overestimated by ?7%, compared to -11% within LDA and 11% within GGA. The intramolecular geometries are retained, while the intermolecular distances and orientations are significantly improved relative to LDA and GGA. The quality is superior to that achieved with tailor-made empirical VDW corrections ad hoc [M. G. Del Po?polo, C. Pinilla, and P. Ballone, J. Chem. Phys. 126, 144705 (2007)]. We also analyse the performance of an optimized version of this non-empirical functional, where the screening properties of the exchange have been tuned to reproduce high-level quantum chemical calculations [J. Klimes, D. Bowler, and A. Michaelides, J. Phys.: Condens. Matter 22, 074203 (2010)]. The results for solids are even better with volumes and geometries reproduced within 2% of experimental data. We provide some insight into the issue of polymorphism of [bmim][Cl] crystals, and we present results for the geometry and energetics of [bmim][Tf] and [mmim][Cl] neutral and charged clusters, which validate the use of empirical force fields. PMID:22029322

Kohanoff, Jorge; Pinilla, Carlos; Youngs, Tristan G A; Artacho, Emilio; Soler, José M

2011-10-21

56

Variation of electrochemical capacitor performance with Room Temperature Ionic Liquid electrolyte viscosity and ion size.  

PubMed

The use of Room Temperature Ionic Liquid (RTIL) electrolytes promises to improve the energy density of Electrochemical Capacitors (ECs) by allowing for operation at higher voltages. RTIL electrolytes 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF(4)), 1-ethyl-3-methylimidazolium dicyanamide (EMImN(CN)(2)), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (DMPImTFSI), and 1-butyl-3-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMPyFAP) were studied. Tetraethylammonium tetrafluoroborate 1 molar solution in anhydrous propylene carbonate (Et(4)NBF(4)-PC 1M) was studied for comparison purposes. Carbon was produced from phenolic resin activated in CO(2). The porosity of the carbon samples were characterised by N(2) adsorption-desorption at 77 K and the relevant electrochemical behaviour was characterised by galvanostatic charge-discharge, electrochemical impedance spectroscopy and cyclic voltammetry. The highest operating voltage of 3.5 V was obtained for BMPyFAP, whilst the best capacitive performance was obtained for EMImBF(4). The maximum energy density increased to 70 Wh kg(-1) (carbon) for RTIL EMImBF(4) from 35 Wh kg(-1)(carbon) for the organic electrolyte Et(4)NBF(4)-PC 1M. It was found that the performance of the RTIL electrolytes could be related to the IL viscosity and ion size whilst the electrolyte equivalent series resistances produced a linear relationship with viscosity. It was found that the capacitance performance of the RTIL electrolytes followed the order EMImBF(4) > DMPImTFSI > BMPyFAP > EMImN(CN)(2). The electrolyte and equivalent series resistance were in the order EMImN(CN)(2) < EMImBF(4) < DMPImTFSI < BMPyFAP. PMID:22451012

Sillars, Fiona B; Fletcher, S Isobel; Mirzaeian, Mojtaba; Hall, Peter J

2012-03-26

57

An electrochemical gas sensor based on paper supported room temperature ionic liquids.  

PubMed

A sensitive and fast-responding membrane-free amperometric gas sensor is described, consisting of a small filter paper foil soaked with a room temperature ionic liquid (RTIL), upon which three electrodes are screen printed with carbon ink, using a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs as well as their easy immobilization into a porous and inexpensive supporting material such as paper. Moreover, thanks to a careful control of the preparation procedure, a very close contact between the RTIL and electrode material can be achieved so as to allow gaseous analytes to undergo charge transfer just as soon as they reach the three-phase sites where the electrode material, paper supported RTIL and gas phase meet. Thus, the adverse effect on recorded currents of slow steps such as analyte diffusion and dissolution in a solvent is avoided. To evaluate the performance of this device, it was used as a wall-jet amperometric detector for flow injection analysis of 1-butanethiol vapours, adopted as the model gaseous analyte, present in headspace samples in equilibrium with aqueous solutions at controlled concentrations. With this purpose, the RTIL soaked paper electrochemical detector (RTIL-PED) was assembled by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as the wicking RTIL and printing the working electrode with carbon ink doped with cobalt(II) phthalocyanine, to profit from its ability to electrocatalyze thiol oxidation. The results obtained were quite satisfactory (detection limit: 0.5 ?M; dynamic range: 2-200 ?M, both referring to solution concentrations; correlation coefficient: 0.998; repeatability: ±7% RSD; long-term stability: 9%), thus suggesting the possible use of this device for manifold applications. PMID:22076475

Dossi, Nicolò; Toniolo, Rosanna; Pizzariello, Andrea; Carrilho, Emanuel; Piccin, Evandro; Battiston, Simone; Bontempelli, Gino

2011-11-10

58

Phase behavior of phytosterol ethoxylates in an imidazolium-type room-temperature ionic liquid.  

PubMed

The temperature-concentration phase behavior of nonionic surfactants in an aprotic imidazolium-type room-temperature ionic liquid (RT-IL) was evaluated on the basis of a combination of visual appearance, polarized optical microscopy, and small angle X-ray scattering data. Phytosterol ethoxylates (BPS-n, where n denotes oxyethylene chain lengths of 5, 10, 20, and 30) were used as surfactants in the RT-IL, 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF?). The two component mixtures yielded various phases such as discontinuous cubic, hexagonal, and lamellar phases. An increased tendency toward formation of lesser-curved molecular assemblies was observed at higher BPS-n concentrations, at lower temperatures, and for shorter oxyethylene chain surfactants. These trends are similar to those observed in aqueous BPS-n systems; however, notable differences in the phase states of the aqueous system versus the BmimPF? system were evident. Comparison with the water system showed that the BmimPF? system yielded fewer phases and generally required higher BPS-n concentrations to induce phase transitions. Evaluation of the effects of addition of a third component (e.g., 1-dodecanol and dodecane) to the binary system on the phase behavior showed that at a given composition ratio of BPS-20 to BmimPF?, the addition of 1-dodecanol generally results in the phase transition to lesser-curved assemblies whereas dodecane generated no significant effects. The observed phase change is satisfactorily rationalized by localized solubilization of the third component into the binary surfactant assemblies. PMID:22362144

Sakai, Hideki; Saitoh, Takanori; Misono, Takeshi; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko

2012-01-01

59

Ultrafast FRET in a room temperature ionic liquid microemulsion: a femtosecond excitation wavelength dependence study.  

PubMed

Fluorescence resonance energy transfer (FRET) from coumarin 480 (C480) to rhodamine 6G (R6G) is studied in a room temperature ionic liquid (RTIL) microemulsion by picosecond and femtosecond emission spectroscopy. The microemulsion is comprised of the RTIL 1-pentyl-3-methylimidazolium tetraflouroborate, [pmim][BF4], in TX-100/ benzene. We have studied the microemulsion with and without water. The time constants of FRET were obtained from the risetime of the acceptor (R6G) emission. In the RTIL microemulsion, FRET occurs on multiple time scales: 1, 250, and 3900 ps. In water containing RTIL microemulsion, the rise components are 1.5, 250, and 3900 ps. The 1 and 1.5 ps components are assigned to FRET at a close contact of donor and acceptor (RDA approximately 12 A). This occurs within the highly polar (RTIL/water) pool of the microemulsion. With increase in the excitation wavelength (lambdaex) from 375 to 435 nm, the relative contribution of the ultrafast component of FRET (1 ps) increases from 4% to 100% in the RTIL microemulsion and 12% to 100% in the water containing RTIL microemulsion. It is suggested that at lambdaex = 435 nm, mainly the highly polar RTIL pool is probed where FRET is very fast due to the close proximity of the donor and the acceptor. The very long 3900 ps (RDA approximately 45 A) component may arise from FRET from a donor in the outer periphery of the microemulsion to an acceptor in the polar RTIL pool. The 250 ps component (RDA approximately 29 A) is assigned to FRET from a donor inside the surfactant chains. PMID:19127996

Adhikari, Aniruddha; Das, Dibyendu Kumar; Sasmal, Dibyendu Kumar; Bhattacharyya, Kankan

2009-04-23

60

Room temperature ionic liquid as solvent for in situ Pd/H formation: hydrogenation of carbon-carbon double bonds.  

PubMed

This work undertakes mechanistic studies of H(+) reduction on a palladium microelectrode in a room temperature ionic liquid. It was found that the electrode was initially in a partially passivated state in [NTf(2)](-) based RTILs and that pre-anodisation of the electrode surface has a dramatic effect on the reversibility of the system, also triggering a change from hydrogen evolution to hydrogen absorption. Theoretical modelling supported the idea of Pd/H formation under these conditions. Utilising Pd/H as an activated hydrogen source, a proof-of-concept method for hydrogenation of multiple bond containing organic molecules by in situ generation of Pd/H via reduction of H(+) on palladium in a room temperature ionic liquid has been demonstrated. PMID:23223389

Martindale, Benjamin C M; Menshykau, Dzianis; Ernst, Sven; Compton, Richard G

2013-01-28

61

Room-temperature ionic liquids and composite materials: platform technologies for CO(2) capture.  

PubMed

Clean energy production has become one of the most prominent global issues of the early 21st century, prompting social, economic, and scientific debates regarding energy usage, energy sources, and sustainable energy strategies. The reduction of greenhouse gas emissions, specifically carbon dioxide (CO(2)), figures prominently in the discussions on the future of global energy policy. Billions of tons of annual CO(2) emissions are the direct result of fossil fuel combustion to generate electricity. Producing clean energy from abundant sources such as coal will require a massive infrastructure and highly efficient capture technologies to curb CO(2) emissions. Current technologies for CO(2) removal from other gases, such as those used in natural gas sweetening, are also capable of capturing CO(2) from power plant emissions. Aqueous amine processes are found in the vast majority of natural gas sweetening operations in the United States. However, conventional aqueous amine processes are highly energy intensive; their implementation for postcombustion CO(2) capture from power plant emissions would drastically cut plant output and efficiency. Membranes, another technology used in natural gas sweetening, have been proposed as an alternative mechanism for CO(2) capture from flue gas. Although membranes offer a potentially less energy-intensive approach, their development and industrial implementation lags far behind that of amine processes. Thus, to minimize the impact of postcombustion CO(2) capture on the economics of energy production, advances are needed in both of these areas. In this Account, we review our recent research devoted to absorptive processes and membranes. Specifically, we have explored the use of room-temperature ionic liquids (RTILs) in absorptive and membrane technologies for CO(2) capture. RTILs present a highly versatile and tunable platform for the development of new processes and materials aimed at the capture of CO(2) from power plant flue gas and in natural gas sweetening. The desirable properties of RTIL solvents, such as negligible vapor pressures, thermal stability, and a large liquid range, make them interesting candidates as new materials in well-known CO(2) capture processes. Here, we focus on the use of RTILs (1) as absorbents, including in combination with amines, and (2) in the design of polymer membranes. RTIL amine solvents have many potential advantages over aqueous amines, and the versatile chemistry of imidazolium-based RTILs also allows for the generation of new types of CO(2)-selective polymer membranes. RTIL and RTIL-based composites can compete with, or improve upon, current technologies. Moreover, owing to our experience in this area, we are developing new imidazolium-based polymer architectures and thermotropic and lyotropic liquid crystals as highly tailorable materials based on and capable of interacting with RTILs. PMID:19795831

Bara, Jason E; Camper, Dean E; Gin, Douglas L; Noble, Richard D

2010-01-19

62

Separation of N2O and CO2 using Room-Temperature Ionic Liquid [bmim][Ac  

Microsoft Academic Search

We have developed a ternary equation of state (EOS) model for the N2O\\/CO2\\/1-butyl-3-methylimidazolium acetate ([bmim][Ac]) system in order to understand the separation of N2O and CO2 using room-temperature ionic liquids (RTILs). The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical interaction parameters for each binary system. The interaction parameters have been determined using our measured VLE

Mark B. Shiflett; Beth A. Elliott; Anne Marie S. Niehaus; A. Yokozeki

2012-01-01

63

Room temperature ionic liquid as matrix medium for the determination of residual solvents in pharmaceuticals by static headspace gas chromatography  

Microsoft Academic Search

Using new solvent room temperature ionic liquid (IL) matrix media, testing of residual solvents in pharmaceutical preparations with static headspace gas chromatographic (SH-GC), is described. The purpose of this work was to demonstrate the feasibility of IL as diluent, six solvents utilized in synthesis of Adefovir Dipivoxil: acetonitrile, dichloromethane, N-methyl-2-pyrrolidone (NMP), toluene, dimethylformamide (DMF), n-butyl ether were dissolved in IL:

Feng-hua Liu; Ye Jiang

2007-01-01

64

81929 - Fission-Product Separation Based on Room - Temperature Ionic Liquids  

SciTech Connect

This project has demonstrated that Sr2+ and Cs+ can be selectively extracted from aqueous solutions into ionic liquids using crown ethers and that unprecedented large distribution coefficients can be achieved for these fission products. The volume of secondary wastes can be significantly minimized with this new separation technology. Through the current EMSP funding, the solvent extraction technology based on ionic liquids has been shown to be viable and can potentially provide the most efficient separation of problematic fission products from high level wastes. The key results from the current funding period are the development of highly selective extraction process for cesium ions based on crown ethers and calixarenes, optimization of selectivities of extractants via systematic change of ionic liquids, and investigation of task-specific ionic liquids incorporating both complexant and solvent characteristics.

Robin D. Rogers

2004-12-09

65

Electrodeposition of platinum nanoparticles in a room-temperature ionic liquid.  

PubMed

The electrochemistry of the [PtCl(6)](2-)-[PtCl(4)](2-)-Pt redox system on a glassy carbon (GC) electrode in a room-temperature ionic liquid (RTIL) [i.e., N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEMEBF(4))] has been examined. The two-step four-electron reduction of [PtCl(6)](2-) to Pt, i.e., reduction of [PtCl(6)](2-) to [PtCl(4)](2-) and further reduction of [PtCl(4)](2-) to Pt, occurs separately in this RTIL in contrast to the one-step four-electron reduction of [PtCl(6)](2-) to Pt in aqueous media. The cathodic and anodic peaks corresponding to the [PtCl(6)](2-)/[PtCl(4)](2-) redox couple were observed at ca. -1.1 and 0.6 V vs a Pt wire quasi-reference electrode, respectively, while those observed at -2.8 and -0.5 V were found to correspond to the [PtCl(4)](2-)/Pt redox couple. The disproportionation reaction of the two-electron reduction product of [PtCl(6)](2-) (i.e., [PtCl(4)](2-)) to [PtCl(6)](2-) and Pt metal was also found to occur significantly. The electrodeposition of Pt nanoparticles could be carried out on a GC electrode in DEMEBF(4) containing [PtCl(6)](2-) by holding the potential at -3.5 or -2.0 V. At -3.5 V, the four-electron reduction of [PtCl(6)](2-) to Pt can take place, while at -2.0 V the two-electron reduction of [PtCl(6)](2-) to [PtCl(4)](2-) occurs. The results obtained demonstrate that the electrodeposition of Pt at -3.5 V may occur via a series of reductions of [PtCl(6)](2-) to [PtCl(4)](2-) and further [PtCl(4)](2-) to Pt and at -2.0 V via a disproportionation reaction of [PtCl(4)](2-) to [PtCl(6)](2-) and Pt. Furthermore, the deposition potential of Pt nanoparticles was found to largely influence their size and morphology as well as the relative ratio of Pt(110) and Pt(100) crystalline orientation domains. The sizes of the Pt nanoparticles prepared by holding the electrode potential at -2.0 and -3.5 V are almost the same, in the range of ca. 1-2 nm. These small nanoparticles are "grown" to form bigger particles with different morphologies: In the case of the deposition at -2.0 V, the GC electrode surface is totally, relatively compactly covered with Pt particles of relatively uniform size of ca. 10-50 nm. On the other hand, in the case of the electrodeposition at -3.5 V, small particles of ca. 50-100 nm and the grown-up particles of ca. 100-200 nm cover the GC surface irregularly and coarsely. Interestingly, the Pt nanoparticles prepared by holding the potential at -2.0 and -3.5 V are relatively enriched in Pt(100) and Pt(110) facets, respectively. PMID:21995596

Zhang, Da; Chang, Wan Cheng; Okajima, Takeyoshi; Ohsaka, Takeo

2011-11-08

66

Highly efficient extraction of phenolic compounds by use of magnetic room temperature ionic liquids for environmental remediation  

Microsoft Academic Search

A hydrophobic magnetic room temperature ionic liquid (MRTIL), trihexyltetradecylphosphonium tetrachloroferrate(III) ([3C6PC14][FeCl4]), was synthesized from trihexyltetradecylphosphonium chloride and FeCl3·6H2O. This MRTIL was investigated as a possible separation agent for solvent extraction of phenolic compounds from aqueous solution. Due to its strong paramagnetism, [3C6PC14][FeCl4] responds to an external neodymium magnet, which was employed in the design of a novel magnetic extraction technique.

Ning Deng; Min Li; Lijie Zhao; Chengfei Lu; Sergio L. de Rooy; Isiah M. Warner

2011-01-01

67

Visible photoluminescence of gold nanoparticles prepared by sputter deposition technique in a room-temperature ionic liquid  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) is observed for gold nanoparticles prepared by using sputter deposition technique and stably dispersed in a room-temperature ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate. PL spectrum in the visible region depends on the excitation wavelength; the spectrum is shifted to longer wavelengths, as the excitation wavelength becomes longer, which probably comes from the size distribution of nanoparticles. Decay profiles as well as quantum yields of PL are measured at different excitation wavelengths. PL intensity shows a multiexponential decay, and the average lifetime, which depends on the excitation wavelength, is shorter than 3 ns.

Iimori, Toshifumi; Hatakeyama, Yoshikiyo; Nishikawa, Keiko; Kato, Masako; Ohta, Nobuhiro

2013-10-01

68

Computing thermodynamic and transport properties of room temperature ionic liquids and molten salts from atomistic simulations  

NASA Astrophysics Data System (ADS)

Ionic liquids and molten salts are being considered for many novel applications including for use as heat transfer fluids in thermal energy generation cycles. Thermodynamic and transport properties like melting points, heat capacities, viscosities and thermal conductvities were computed for some ionic liquids and molten salts. Melting points were computed using a novel thermodynamic integration-based procedure. Apart from computing melting points, relative thermodynamic stabilities of crystal polymorphs can be obtained using this method. The melting point and the relative stabilities of two polymorphs of the ionic liquid 1-n-butyl-3-methylimidazolium chloride were computed and were found to be comparable to experimental data. Melting points were computed for lithium, sodium and potassium nitrate salts, which are being considered as candidates for heat transfer media in solar thermal applications. Viscosities, thermal conductivities and heat capacities were also computed for these salts. The numbers were comparable to experimental data. The difference between the experimentally determined properties, and the values obtained from simulations can be attributed to the parameterization of the force field model used for these salts. In addition to pure component properties, transport properties such as self-diffusivities, viscosities and thermal conductivities were computed for ionic liquid and alkali nitrate salt mixtures. Various mixing rules were fit to these properties. The results of these studies suggest that accurate melting points are a sensitive test of force field accuracy. Also, powerful molecular simulation methods are capable of computing properties useful in the design of fluids targeting a particular application. In addition, the thermodynamic integration-based procedure is modified to compute solid phase free energies which is used to calculate solubilities of solids in liquids. Enthalpies of vaporization of ionic liquids were also computed and this data will be used to verify vaporization enthalpies measured experimentally.

Jayaraman, Saivenkataraman

69

Electrochemistry and spectroscopy of electrolytes and cathode materials in room-temperature ionic liquids  

NASA Astrophysics Data System (ADS)

The demonstration of a stable, reversible, alkali metal anode is an important step in the development of practical secondary batteries using room temperature chloroaluminate molten salts as electrolytes. Such melts are made by mixing 1-ethyl-3-methylimidazolium chloride (EMIC) with aluminum chloride, and can be Lewis buffered by adding LiCl or NaCl. It has been shown previously that protons added to a sodium chloride buffered melt as 1-ethyl-3-methyfimidazolium hydrogen dichloride (EMIHCl2) provide a more negative voltage window and nearly reversible deposition-stripping behavior for sodium. It is reported here that triethanolamine hydrogen chloride is effective in widening the voltage window, allows the plating and stripping of both lithium and sodium, and is stable in buffered EMIC/AlCl3 melts for months. It is suggested that deprotonation of one ethanolic group of triethanolamine HCl is responsible for the effect. The electrochemistry and UV-visible spectroscopy of several vanadium oxides have been examined in room temperature melts. By varying the mole ratio of the two components, Lewis basic, neutral and acidic melts were made. Most oxides have very low solubility: V2O4 and V2O3 are insoluble and V2O5 has a solubility limit less than 5 mM, but the solubilities of the salts NaVO 3, Na3VO4, and NH4VO3, VOCl 3 and VOF3 are significantly higher. The electrochemistry of V2O5, NaVO3, Na3VO4, NH4VO3, VOCl3 and VOF3 is similar in neutral and acidic melts. In the neutral melt each compound shows an irreversible reduction at about 0.45V vs. an Al wire reference electrode. In an acidic melt (mole fraction AlCl3 = 0.55) each of these compounds exhibit additional reduction peaks at more positive potentials. Coulometric and spectroscopic data for the 0.45V reduction suggest that mixed oxidation state polyvanadates may be formed. Controlled potential coulometry demonstrated that the reduction at 0.45V was the reduction of V(V) to V(IV) and the more positive reduction peaks were caused by the reduction of some other species of V(V) present in the acidic melts. New room temperature melts have been prepared by mixing Lewis acidic, VOCl3, with Lewis basic, EMIC. The new melts are dark red homogeneous liquids that are very conductive and easily reduced.

Ryan, David Martin

70

Solubility of room-temperature ionic liquid in supercritical CO2 with and without organic compounds.  

PubMed

Ionic liquid can dramatically dissolve in supercritical (sc) CO2 with polar organic compounds (ethanol, acetone) especially as the concentration of the compounds in scCO2 exceeds 10 mol%, while the effect of a nonpolar organic compound (n-hexane) in scCO2 on the solubility is very limited even when its concentration is as high as 30 mol%. PMID:12841267

Wu, Weize; Zhang, Jianmin; Han, Buxing; Chen, Jiawei; Liu, Zhimin; Jiang, Tao; He, Jun; Li, Wenjing

2003-06-21

71

Room-temperature ionic liquids discerned via nitroxyl spin probe dynamics.  

PubMed

The temperature dependence of the rotational correlation times, ?(c), of the nitroxide spin probes TEMPO, TEMPOL, TEMPAMINE, and Fremy's salt in the ionic liquids 1-ethyl-3-methylimidazolium ethylsulfate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium tetrafluoroborate is scrutinized. The rotation correlation times vary between 54 and 1470 ps at 300 K. Within a temperature range of 280-380 K, the rotational tumbling is well described by the extended Debye-Stokes-Einstein law. The hydrodynamic radii are smaller than the geometrical radii though. This discrepancy can partly be accounted for by microviscosity effects and deviations from the spherical shape. This study is distinguished from similar studies by the fact that proton superhyperfine coupling constants could be resolved for all nitroxides in the ionic liquids by carefully optimizing the experimental protocol. As a consequence, many rotational correlation times reported here are smaller than those found previously. Furthermore, the temperature dependence of the nitrogen ESR coupling constants is reported and discussed in detail. A surprising effect of adventitious water is reported for TEMPAMINE. PMID:21634394

Mladenova, Boryana Y; Kattnig, Daniel R; Grampp, Günter

2011-06-02

72

Separation of carbon dioxide and sulfur dioxide gases using room-temperature ionic liquid (hmim)(Tf2N)  

SciTech Connect

To understand capturing and/or enhanced gaseous selectivity of industrial flue gases containing CO{sub 2} and SO{sub 2} using room-temperature ionic liquids, we have developed a ternary equation of state (EOS) model for a CO{sub 2}/SO{sub 2}/1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((hmim)(Tf2N)) system. The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical binary interaction parameters of each binary system. These interaction parameters have been determined using our measured VLE (vapor-liquid-equilibrium) data for SO{sub 2}/(hmim)(Tf2N) and CO{sub 2}/(hmim)(Tf2N) and literature data for CO{sub 2}/SO{sub 2}. The validity of the present EOS has been checked by conducting ternary VLE experiments for the present system. With this EOS, isothermal ternary phase diagrams and solubility (VLE) behaviors have been calculated for various (T, P, and feed compositions) conditions. For large and equimolar CO{sub 2}/SO{sub 2} mole ratios, the gaseous selectivity is nearly independent of the amount of the ionic liquid addition. However, for small CO{sub 2}/SO{sub 2} mole ratios the addition of the ionic liquid significantly increases the selectivity. The strong absorption of CO{sub 2} and SO{sub 2} in this ionic liquid may be practical for the simultaneous capture of these acid gases. 39 refs., 8 figs., 4 tabs.

A. Yokozeki; Mark B. Shiflett

2009-09-15

73

Facile preparation of polysaccharide-coated capillaries using a room temperature ionic liquid for chiral separations.  

PubMed

In this study, the dissolution of polysaccharides into an ionic liquid was investigated and applied as a coating onto the capillary walls of a fused-silica capillary in open-tubular CEC. The coating was evaluated by examining the chiral separation of two analytes (thiopental, sotalol) with three cellulose derivatives (cellulose acetate, cellulose acetate phthalate, and cellulose acetate butyrate). Baseline separation of thiopental enantiomers was achieved by use of each polysaccharide coating (Rs: 7.0, 8.1, 7.1), while sotalol provided partial resolution (Rs: 0.7, 1.0, 0.9). In addition, reproducibility of the cellulose-coated capillaries was evaluated by estimating the run-to-run and capillary-to-capillary RSD values of the EOF. Both stability and reproducibility were very good with RSD values of less than 7%. PMID:23463600

Stavrou, Ioannis J; Moore, Leonard; Fernand, Vivian E; Kapnissi-Christodoulou, Constantina P; Warner, Isiah M

2013-05-01

74

Electrochemistry and spectroscopy of electrolytes and cathode materials in room-temperature ionic liquids  

Microsoft Academic Search

The demonstration of a stable, reversible, alkali metal anode is an important step in the development of practical secondary batteries using room temperature chloroaluminate molten salts as electrolytes. Such melts are made by mixing 1-ethyl-3-methylimidazolium chloride (EMIC) with aluminum chloride, and can be Lewis buffered by adding LiCl or NaCl. It has been shown previously that protons added to a

David Martin Ryan

2000-01-01

75

Differential scanning calorimetric study of nonionic surfactant mixtures with a room temperature ionic liquid, bmimBF4.  

PubMed

The melting behavior of polyethyleneglycol dodecyl ethers (C(12)E(6), C(12)E(7), and C(12)E(8)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), was investigated by means of differential scanning calorimetry (DSC). The melting temperature as a function of the surfactant concentration, combined with the cmc curve and cloud point curve, provided phase diagrams for the surfactant/bmimBF(4) mixtures in solvent-rich region. The characteristic feature of the mixtures is an existence of the Krafft temperature which is usually not observed with aqueous solutions of nonionic surfactants. The heat of fusion as a function of the surfactant concentration provided the interaction energy between the surfactant and bmimBF(4). The interaction energy shows a linear dependence on the length of polyoxyethylene (POE) chain of the surfactants, which suggests that the solvation takes place around the POE chain. PMID:19501832

Inoue, Tohru; Higuchi, Yuka; Misono, Takeshi

2009-05-20

76

Room temperature ionic liquid as matrix medium for the determination of residual solvents in pharmaceuticals by static headspace gas chromatography.  

PubMed

Using new solvent room temperature ionic liquid (IL) matrix media, testing of residual solvents in pharmaceutical preparations with static headspace gas chromatographic (SH-GC), is described. The purpose of this work was to demonstrate the feasibility of IL as diluent, six solvents utilized in synthesis of Adefovir Dipivoxil: acetonitrile, dichloromethane, N-methyl-2-pyrrolidone (NMP), toluene, dimethylformamide (DMF), n-butyl ether were dissolved in IL: 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)). The method of external standard was used for quantitative analysis. Its performance was evaluated and validated: all the RSD were lower than 10%, the limits of detection were all of the ppm level and the method was both accurate and linear. And better sensitivities for the six solvents were gained with [bmim]BF(4) as diluent comparing with DMSO. PMID:17765909

Liu, Feng-Hua; Jiang, Ye

2007-08-17

77

Highly efficient extraction of phenolic compounds by use of magnetic room temperature ionic liquids for environmental remediation.  

PubMed

A hydrophobic magnetic room temperature ionic liquid (MRTIL), trihexyltetradecylphosphonium tetrachloroferrate(III) ([3C(6)PC(14)][FeCl(4)]), was synthesized from trihexyltetradecylphosphonium chloride and FeCl(3) · 6H(2)O. This MRTIL was investigated as a possible separation agent for solvent extraction of phenolic compounds from aqueous solution. Due to its strong paramagnetism, [3C(6)PC(14)][FeCl(4)] responds to an external neodymium magnet, which was employed in the design of a novel magnetic extraction technique. The conditions for extraction, including extraction time, volume ratio between MRTIL and aqueous phase, pH of aqueous solution, and structures of phenolic compounds were investigated and optimized. The magnetic extraction of phenols achieved equilibrium in 20 min and the phenolic compounds were found to have higher distribution ratios under acidic conditions. In addition, it was observed that phenols containing a greater number of chlorine or nitro substituents exhibited higher distribution ratios. For example, the distribution ratio of phenol (D(Ph)) was 107. In contrast, 3,5-dichlorophenol distribution ratio (D(3,5-DCP)) had a much higher value of 6372 under identical extraction conditions. When compared with four selected traditional non-magnetic room temperature ionic liquids, our [3C(6)PC(14)][FeCl(4)] exhibited significantly higher extraction efficiency under the same experimental conditions used in this work. Pentachlorophenol, a major component in the contaminated soil sample obtained from a superfund site, was successfully extracted and removed by use of [3C(6)PC(14)][FeCl(4)] with high extraction efficiency. Pentachlorophenol concentration was dramatically reduced from 7.8 ?g mL(-1) to 0.2 ?g mL(-1) after the magnetic extraction by use of [3C(6)PC(14)][FeCl(4)]. PMID:21783320

Deng, Ning; Li, Min; Zhao, Lijie; Lu, Chengfei; de Rooy, Sergio L; Warner, Isiah M

2011-06-25

78

Interfacial layering of a room-temperature ionic liquid thin film on mica: a computational investigation.  

PubMed

The structure of a thin (4 nm) [bmim][Tf(2)N] film on mica was studied by molecular dynamics simulations using an empirical force field. Interfacial layering at T=300 K and at T=350 K is investigated by determining the number- and charge-density profiles of [bmim][Tf(2)N] as a function of distance from mica, and by computing the normal force F(z) opposing the penetration of the ionic liquid film by a spherical nanometric tip interacting with [bmim][Tf(2)N] atoms by a short-range potential. The results show that layering is important but localised within ~1 nm from the interface. The addition of a surface charge on mica, globally neutralised by an opposite charge on the [bmim][Tf(2)N] side, gives rise to low-amplitude charge oscillations extending through the entire film. However, outside a narrow interfacial region, the resistance of the [bmim][Tf(2)N] film to penetration by the mesoscopic tip is only marginally affected by the charge at the interface. The results obtained here for [bmim][Tf(2)N]/mica are similar to those obtained using the same method for the [bmim][Tf(2)N]/silica interface, and agree well with experimental force-distance profiles measured on the latter interface at ambient conditions. PMID:22392886

Dragoni, Daniele; Manini, Nicola; Ballone, Pietro

2012-03-05

79

Electrochemical gas sensors based on paper-supported room-temperature ionic liquids for improved analysis of acid vapours.  

PubMed

A prototype of a fast-response task-specific amperometric gas sensor based on paper-supported room-temperature ionic liquids (RTILs) is proposed here for improved analysis of volatile acid species. It consists of a small filter paper foil soaked with a RTIL mixture containing an ionic liquid whose anion (acetate) displays a basic character, upon which three electrodes are screen printed by carbon ink profiting from a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs and of their easy immobilization into a porous and inexpensive supporting material such as paper. The performance of this device, used as a wall-jet amperometric detector for flow injection analyses of headspace samples in equilibrium with aqueous solutions at controlled concentrations, was evaluated for phenol and 1-butanethiol vapours which were adopted as model acid gaseous analytes. The results obtained showed that the quite high potentials required for the detection of these analytes are lowered significantly, thanks to the addition of the basic acetate RTIL. In such a way, overlap with the medium discharge is avoided, and the possible adverse effect of interfering species is minimised. The sensor performance was quite satisfactory (detection limits, ca. 0.3 ?M; dynamic range, ca. 1-200 ?M, both referred to solution concentrations; correlation coefficients in the range 0.993-0.997; repeatability, ± 6% RSD; long-term stability, 9%); thus suggesting the possible use of this device for manifold applications. PMID:23232956

Toniolo, Rosanna; Dossi, Nicolò; Pizzariello, Andrea; Casagrande, Alice; Bontempelli, Gino

2012-12-13

80

Facile pretreatment of lignocellulosic biomass at high loadings in room temperature ionic liquids.  

PubMed

Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biofuels and chemical feedstocks. However, the high cost of ILs is a key deterrent to their practical application. Here, we show that acetate based ILs are effective in dramatically reducing the recalcitrance of corn stover toward enzymatic polysaccharide hydrolysis even at loadings of biomass as high as 50% by weight. Under these conditions, the IL serves more as a pretreatment additive rather than a true solvent. Pretreatment of corn stover with 1-ethyl-3-methylimidizolium acetate ([Emim] [OAc]) at 125 ± 5°C for 1 h resulted in a dramatic reduction of cellulose crystallinity (up to 52%) and extraction of lignin (up to 44%). Enzymatic hydrolysis of the IL-treated biomass was performed with a common commercial cellulase/xylanase from Trichoderma reesei and a commercial ?-glucosidase, and resulted in fermentable sugar yields of ?80% for glucose and ?50% for xylose at corn stover loadings up to 33% (w/w) and 55% and 34% for glucose and xylose, respectively, at 50% (w/w) biomass loading. Similar results were observed for the IL-facilitated pretreatment of switchgrass, poplar, and the highly recalcitrant hardwood, maple. At 4.8% (w/w) corn stover, [Emim][OAc] can be readily reused up to 10 times without removal of extracted components, such as lignin, with no effect on subsequent fermentable sugar yields. A significant reduction in the amount of IL combined with facile recycling has the potential to enable ILs to be used in large-scale biomass pretreatment. PMID:21769858

Wu, Hong; Mora-Pale, Mauricio; Miao, Jianjun; Doherty, Thomas V; Linhardt, Robert J; Dordick, Jonathan S

2011-08-01

81

Efficient solvent system containing malonamides in room temperature ionic liquids: actinide extraction, fluorescence and radiolytic degradation studies.  

PubMed

Solvent extraction studies of actinide metal ions such as Am(III), U(VI), Np(IV), Np(VI), Pu(IV) were carried out in a nitric acid medium using two diamides (L) viz. (DMDBTDMA (N,N'-dimethyl-N,N'-dibutyl-2-tetradecylmalonamide) and DMDOHEMA (N,N'-dimethyl-N,N'-dioctyl-2-(2'-(hexyloxy)ethyl)-malonamide) dissolved in different room temperature ionic liquids (RTILs). The use of RTILs as the diluent significantly enhanced metal ion extraction as compared to that observed in non polar diluent such as n-dodecane. The effects of parameters such as kinetics, aqueous phase acidity (0.01-3 M HNO(3)), metal ion oxidation states, diamide concentration on the extraction of metal ions were studied. The stoichiometry of the extracted Am(III) species using these diamides varied with ligand concentration viz. (Am.3L)(3+) ([L] = 0.005-0.02 M) and (Am.2-2.5L)(3+) ([L] = 0.05-0.1 M). Time resolved laser induced fluorescence spectroscopy (TRLFS) studies showed that the extracted species of Eu(III) in an ionic liquid medium had no coordinated water molecules, in contrast to the presence of 1-2 water molecules in the extracted species in a n-dodecane medium. The radiolytic degradation behavior of the diamides/RTIL system has been studied using IR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The data revealed that a significantly lower ligand concentration is required for actinide extraction in ionic liquids as the extraction media as compared to nonpolar diluents. PMID:23135734

Patil, Ajay B; Pathak, Priyanath; Shinde, Vaishali S; Godbole, Shrikant V; Mohapatra, Prasanta K

2012-11-08

82

Acoustics as a tool for better characterization of ionic liquids: a comparative study of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide room-temperature ionic liquids.  

PubMed

Acoustic properties of three (1-ethyl-, 1-butyl-, and 1-octyl-) 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide room-temperature ionic liquids are reported and discussed. The speeds of sound in RTILs were measured as a function of temperature in the range 288-323 K by means of a sing around method. The densities and isobaric heat capacities were determined from 288.15 to 363.15 K and from 293.15 to 323.15 K, respectively. The related properties, like isentropic and isothermal compressibilities, isobaric coefficients of thermal expansion, molar isochoric heat capacities, and internal pressures, were calculated. It was found that for some ionic liquids, temperature dependence of isobaric coefficients of thermal expansion is small and negative. All investigations were completed by the ultrasound absorption coefficient measurements in 1-ethyl- and 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide as a function of frequency from 10 to 300 MHz at temperatures 293.15-298.15 K. The ultrasound absorption spectra indicate relaxation frequencies in the megahertz range. PMID:23510074

Zor?bski, Edward; Geppert-Rybczy?ska, Monika; Zor?bski, Micha?

2013-04-01

83

Room temperature ionic liquids as useful overlayers for estimating food quality from their odor analysis by quartz crystal microbalance measurements.  

PubMed

An array of quartz crystals coated with different room-temperature ionic liquids (RTILs) is proposed for the analysis of flavors by quartz crystal microbalance (QCM) measurements. Seven RTILs were adopted as sensing layers, all containing imidazolium or phosphonium cations, differing from one another in the length and branching of alkyl groups and neutralized by different anions. The array was at first applied to the analysis of 31 volatile organic compounds (VOCs), such as alcohols, phenols, aldehydes, esters, ketones, acids, amines, hydrocarbons and terpenes, chosen as representative components of a wide variety of food flavors. Multivariate data analysis by the principal component analysis (PCA) approach of the set of the corresponding responses led to separated clusters for these different chemical categories. To further prove the good performance of the RTIL-coated quartz crystal array as an "electronic nose", it was applied to the analysis of headspaces from cinnamon samples belonging to different botanical varieties ( Cinnamon zeylanicum and Cinnamon cassia ). PCA applied to responses recorded on different stocks of samples of both varieties showed that they could be fully discriminated. PMID:23808811

Toniolo, Rosanna; Pizzariello, Andrea; Dossi, Nicolò; Lorenzon, Stefano; Abollino, Ornella; Bontempelli, Gino

2013-07-24

84

Superpressing of a Room Temperature Ionic Liquid, 1-Ethyl-3-methylimidazolium Tetrafluoroborate.  

PubMed

We have investigated the phase behavior of 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) at 298 K under high pressure conditions. We found that [emim][BF4] can be superpressed without crystallization up to ?7 GPa. We propose that [emim][BF4] behaves as a superpressurized glass above 2.8 GPa. In view of the results, the environment around the alkyl-chain (C6 and C7-C8) of [emim][BF4] is largely perturbed rather than that around the imidazolium-ring in the superpressed state. We also discussed the results in view of the conformational isomerism of [emim](+) cation. Remarkably, as an alternative to pressure-induced crystallization, we have found that such a metastable liquid shows crystal polymorphism around 2.0 and 1.0 GPa upon decompression. The behavior is in contrast with the earlier results of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). PMID:24020694

Yoshimura, Yukihiro; Abe, Hiroshi; Takekiyo, Takahiro; Shigemi, Machiko; Hamaya, Nozomu; Wada, Ryoichi; Kato, Minoru

2013-09-26

85

Ultraslow dynamics at crystallization of a room-temperature ionic liquid, 1-butyl-3-methylimidazolium bromide.  

PubMed

We studied the crystallization process of 1-butyl-3-methylimidazolium bromide ([C(4)mim]Br) using measurements of supersensitive scanning calorimetry, free induction decay (FID) signals of (1)H NMR, and direct observation. These three methods provided consistent, complementary results, which showed extremely slow dynamics at crystallization. This sample does not crystallize during the cooling process, loses mobility, and changes to a coagulated state, which is not the thermodynamic glass state. The FID signals and direct observation in the heating process indicate that the coagulated sample liquefies just before crystallization. The crystallization of [C(4)mim]Br does not occur from specialized locations such as the surface or wall of the sample tube but randomly in the liquid. The calorimetric measurements show that it takes 150 min for approximately 3 mg of this sample to crystallize perfectly. Conformational changes of the butyl group continue for approximately 330 min after crystallization. Such slow dynamics are thought to be due to the cooperative linking of crystallization and complex conformational changes in dense fields with high viscosity. PMID:22409655

Imanari, Mamoru; Fujii, Kozo; Endo, Takatsugu; Seki, Hiroko; Tozaki, Ken-ichi; Nishikawa, Keiko

2012-03-23

86

Volumetric Study of Binary Solvent Mixtures Constituted by Amphiphilic Ionic Liquids at Room Temperature (1Alkyl3-Methylimidazolium Bromide) and Water  

Microsoft Academic Search

At room temperature, the 1-decyl-3-methylimidazolium bromide (DMImBr) is a long alkyl chain imidazolium ionic liquid miscible with water and forming a gel zone between 5 and 40% w\\/w H2O. We measured the density of the liquid mixtures of water and DMImBr. We determined the apparent molar volume of the molten salt for dilute solutions. For the concentrated solutions the partial

Laurent Gaillon; Juliette Sirieix-Plenet; Pierre Letellier

2004-01-01

87

Liquid-liquid extraction of Pu(IV), U(VI) and Am(III) using malonamide in room temperature ionic liquid as diluent.  

PubMed

The extraction behavior of U(VI), Pu(IV) and Am(III) from nitric acid medium by a solution of N,N-dimethyl-N,N-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C(4)mimNTf(2)), was studied. The distribution ratio of these actinides in DMDOHEMA/C(4)mimNTf(2) was measured as a function of various parameters such as the concentration of nitric acid, DMDOHEMA, NTf(2)(-), alkyl chain length of ionic liquid. The extraction of actinides in the absence of DMDOHEMA was insignificant and the distribution ratio achieved in conjunction with C(4)mimNTf(2), was remarkable. The separation factor of U(VI) and Pu(IV) achieved with the use of DMDOHEMA, ionic liquid was compared with Am(III) and other fission products. The stoichiometry of the metal-solvate was determined to be 1:2 for U(VI) and Pu(IV) and 1:3 for Am(III). PMID:22541638

Rout, Alok; Venkatesan, K A; Srinivasan, T G; Vasudeva Rao, P R

2012-04-10

88

Application of the transient grating method to the investigation of the photo-thermalization process of malachite green in room temperature ionic liquids  

Microsoft Academic Search

Transient grating spectroscopy has been applied to the investigation of the photo-thermalization process of malachite green (MG) in several imidazolium-based room temperature ionic liquids (RTILs). MG was simultaneously photo-excited to the S2 state by two sub-picosecond laser pulses (390 nm) with an angle of 30°, and the time profile of the transient grating due to the population and energy dynamics of

M. Fukuda; O. Kajimoto; M. Terazima; Y. Kimura

2007-01-01

89

Electrodeposition behavior of nickel in the water- and air-stable 1-ethyl-3-methylimidazolium-dicyanamide room-temperature ionic liquid  

Microsoft Academic Search

The electrodeposition behavior of nickel was investigated at glassy carbon and polycrystalline copper electrodes in the 1-ethyl-3-methylimidazolium dicyanamide (EMI-DCA) room-temperature ionic liquid. Amperometric titration experiments suggest that Ni(II) reacted with DCA? anions forming [Ni(DCA)4]2? complex anion, which could be reduced to nickel metal via a single-step electron transfer process. However, the anodic dissolution of the nickel deposits was sluggish. The

Ming-Jay Deng; I.-Wen Sun; Po-Yu Chen; Jeng-Kuei Chang; Wen-Ta Tsai

2008-01-01

90

Direct electrochemistry and electrocatalysis of hemoglobin on chitosan-room temperature ionic liquid-TiO 2-graphene nanocomposite film modified electrode  

Microsoft Academic Search

TiO2-graphene nanocomposite was prepared by hydrolysis of titanium isopropoxide in colloidal suspension of graphene oxide and in situ hydrothermal treatment. The direct electrochemistry and electrocatalysis of hemoglobin in room temperature ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate, chitosan and TiO2-graphene nanocomposite modified glassy carbon electrode were investigated. The biosensor was examined by using UV-vis spectroscopy, scanning electron microscopy and electrochemical methods. The results

Jun-Yong Sun; Ke-Jing Huang; Su-Fang Zhao; Yang Fan; Zhi-Wei Wu

2011-01-01

91

Effect of nitrate, perchlorate, and water on uranyl(VI) speciation in a room-temperature ionic liquid: a spectroscopic investigation.  

PubMed

Room-temperature ionic liquids form potentially important solvents in novel nuclear waste reprocessing methods, and the solvation, speciation, and complexation behaviors of lanthanides and actinides in these solvents are of great current interest. In the study reported here, the coordination environment of uranyl(VI) in solutions of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf(2)N]) containing perchlorate, tetrabutylammonium nitrate, and water was investigated using Raman, ATR-FTIR, and NMR spectroscopies in order to better understand the role played in uranyl(VI) solution chemistry in room-temperature ionic liquids by water and other small, weakly complexing ligands. The (2)H NMR chemical shift for water in a solution of uranyl perchlorate hexahydrate in [EMIM][Tf(2)N] appears at 6.52 ppm, indicating that water is coordinated to uranyl(VI). A broad ?(OH) stretching mode at 3370 cm(-1) in the ATR-FTIR spectrum shows that this coordinated water is engaged in hydrogen bonding with water molecules in a second coordination sphere. A significant upfield shift in the (2)H NMR signal for water and the appearance of distinct ?(as)(HOH) (at 3630 cm(-1)) and ?(s)(HOH) (at 3560 cm(-1)) vibrational bands in the ATR-FTIR spectra show that coordinated water is displaced by nitrate upon formation of the UO(2)(NO(3))(2) and UO(2)(NO(3))(3)(-) complexes. The Raman spectra indicate that perchlorate complexed to uranyl(VI) is also displaced by nitrate. Our results indicate that perchlorate and water, though weakly complexing ligands, do have a role in uranyl(VI) speciation in room-temperature ionic liquids and that Raman, infrared, and NMR spectroscopies are valuable additions to the suite of tools currently used to study the chemical behavior of uranyl(VI)-ligand complexes in these solvents. PMID:21786806

Pasilis, Sofie P; Blumenfeld, Alexander

2011-07-25

92

Nanoscale Pt(0) particles prepared in imidazolium room temperature ionic liquids: synthesis from an organometallic precursor, characterization, and catalytic properties in hydrogenation reactions.  

PubMed

The reaction of Pt(2)(dba)(3) (dba = bis-dibenzylidene acetone) dispersed in room temperature 1-n-butyl-3-methylimidazolium (BMI) hexafluorophosphate ionic liquid with molecular hydrogen (4 atm) at 75 degrees C leads to stable and isolable nanometric Pt(0) particles. The X-ray diffraction analysis (XRD) of the material indicated that it is constituted of Pt(0). Transmission electron microscopy (TEM) analysis of the particles dispersed in the ionic liquid shows the formation of [Pt(0)](n) nanoparticles of 2.0-2.5 nm in diameter. A detailed examination of the nanoparticles imbibed in the ionic liquid and their environment shows an interaction of the BMI.PF(6) ionic liquid with the Pt(0) nanoparticles. The isolated [Pt(0)](n) nanoparticles can be redispersed in the ionic liquid or in acetone or used in solventless conditions for liquid-liquid biphasic, homogeneous, or heterogeneous hydrogenation of alkenes and arenes under mild reaction conditions (75 degrees C and 4 atm). The recovered platinum nanoparticles can be reused as a solid or redispersed in the ionic liquid several times without any significant loss in catalytic activity. PMID:12870966

Scheeren, Carla W; Machado, Giovanna; Dupont, Jairton; Fichtner, Paulo F P; Texeira, Sérgio Ribeiro

2003-07-28

93

Novel Fission-Product Separation Based on Room-Temperature Ionic Liquids. (Report for September 15, 2001-September 14, 2004).  

National Technical Information Service (NTIS)

This project has demonstrated that Sr2+ and Cs+ can be selectively extracted from aqueous solutions into ionic liquids using crown ethers and that unprecedented large distribution coefficients can be achieved for these fission products. The volume of seco...

2004-01-01

94

Green and moisture-stable Lewis acidic ionic liquids (choline chloride · xZnCl 2) catalyzed protection of carbonyls at room temperature under solvent-free conditions  

Microsoft Academic Search

Choline chloride·xZnCl2 (x=1–3) or benzyltrimethylammonium chloride·2ZnCl2 have been used as efficient and recyclable catalysts for protection of carbonyls to 1,3-dioxolanes and 1,3-dioxanes at room temperature under solvent-free conditions. FT-IR investigation demonstrates the four ionic liquids have similar Lewis acid strength, which is in agreement with the activities observed in the acetalization reaction. The catalytic system choline chloride·2ZnCl2 can be reused

Zhiying Duan; Yanlong Gu; Youquan Deng

2006-01-01

95

Predicting the partitioning of biological compounds between room-temperature ionic liquids and water by means of the solvation-parameter model  

Microsoft Academic Search

The partition coefficients, P\\u000a IL\\/w, for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids\\u000a (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF6], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF4] and water were accurately measured. [BMIM][PF6] and [OMIM][BF4] were synthesized by adapting a procedure from the literature to a simpler, single-vessel and faster methodology, with a\\u000a much lesser

Juan M. Padró; Agustín Ponzinibbio; Leidy B. Agudelo Mesa; Mario Reta

2011-01-01

96

Solvation of “big” spherical solutes in room temperature ionic liquids and at their aqueous interface: A molecular dynamics simulation study  

Microsoft Academic Search

We report a molecular dynamics study of the solvation of spherical solutes Sq of ca. 5 Å radius in ionic liquids (ILs) based on the PF6? anion and the 1-butyl-3-methylimidazolium cation (BMI+) or 1-octyl-3-methylimidazolium cation (OMI+), as a function of the sign and magnitude of the charge q=0, ±1, ±2 and ±4 of Sq. The simulations highlight the dual solvation properties

A. Chaumont; G. Wipff

2007-01-01

97

Small volume laboratory on a chip measurements incorporating the quartz crystal microbalance to measure the viscosity-density product of room temperature ionic liquids  

PubMed Central

A microfluidic glass chip system incorporating a quartz crystal microbalance (QCM) to measure the square root of the viscosity-density product of room temperature ionic liquids (RTILs) is presented. The QCM covers a central recess on a glass chip, with a seal formed by tightly clamping from above outside the sensing region. The change in resonant frequency of the QCM allows for the determination of the square root viscosity-density product of RTILs to a limit of ?10 kg m?2 s?0.5. This method has reduced the sample size needed for characterization from 1.5 ml to only 30 ?l and allows the measurement to be made in an enclosed system.

Doy, N.; McHale, G.; Newton, M. I.; Hardacre, C.; Ge, R.; MacInnes, J. M.; Kuvshinov, D.; Allen, R. W.

2010-01-01

98

18-Crown-6 and dibenzo-18-crown-6 assisted extraction of cesium from water into room temperature ionic liquids and its correlation with stability constants for cesium complexes.  

PubMed

The pH-profiles of the extraction of Cs(+) into four conventional (1-butyl-3-methylimidazolium hexafluorophosphate and bis[trifluoromethyl)sulphonyl]imides of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-(2-ethylhexyl)-3- methylimidazolium) and two novel (trioctylmethylammonium salicylate and tetrahexylammonium dihexylsulfosuccinate) room temperature ionic liquids have been determined both in the absence and in the presence of crown ether (18-crown-6 or dibenzo-18-crown-6). The pH-profiles of distribution ratio of crown ethers have been established in the same conditions. The relationship of cesium extraction efficiency both with the stability of its complexes with crown ethers and crown ethers' distribution ratio has been clarified. PMID:20032873

Vendilo, Andrey G; Djigailo, Dmitry I; Smirnova, Svetlana V; Torocheshnikova, Irina I; Popov, Konstantin I; Krasovsky, Vladimir G; Pletnev, Igor V

2009-12-02

99

Room temperature ionic liquid-based microextraction for vanadium species separation and determination in water samples by electrothermal atomic absorption spectrometry.  

PubMed

A simple microextraction technique based on room temperature ionic liquids (RTILs) for trace V(IV) and V(V) species separation and preconcentration in water samples was developed in this work. Vanadium species microextraction was achieved with a minimal amount of the RTIL 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]) as vanadium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (V-5-Br-PADAP) complex. The speciation analysis was performed based on a modern technique defined as temperature-controlled ionic liquid dispersive liquid phase microextraction (TILDLME). The level of V(IV) species was calculated by difference of total V and V(V) levels. Selectivity among V species was obtained with the use of 1,2-cyclohexanediaminetetraacetic acid (CDTA) as masking agent. Determination of V was developed by direct injection of the RTIL phase into the electrothermal atomic absorption spectrometer (ETAAS). A preconcentration factor of 40 was achieved with only 2 mL of sample. The limit of detection (LOD) obtained under optimum conditions was 4.9 ng L(-1) and the relative standard deviation for 10 replicate determinations at the 0.5 microg L(-1) V level was 4.3%, calculated at peak heights. A correlation coefficient of 0.9961 was achieved. The method was successfully applied for the speciation analysis of V in tap and river water samples. PMID:19362617

Berton, Paula; Martinis, Estefanía M; Martinez, Luis D; Wuilloud, Rodolfo G

2009-03-24

100

Room temperature ionic liquids: new GC stationary phases with a novel selectivity for flavor and fragrance analyses.  

PubMed

Ionic liquids (ILs) are of great interest as moderately polar to polar stationary phases for GC, because their selectivity differs markedly from that of conventionally used phases. In the flavor, fragrance and essential oil fields, analysts often deal with complex mixtures of compounds having similar structural and physical characteristics (e.g., mono- and sesquiterpenoids), therefore requiring an interactive combination between chromatographic and mass spectral data for correct identification. New GC stationary phases with different selectivity must therefore be continually tested. Performance and evolution over time of commercially available IL columns versus those commonly used in these fields are here evaluated, mainly in view of their routine use. Chromatographic and separative properties (efficiency, separation capability, inertness and/or activity) of commercially available IL columns were compared to those of columns coated with 5% phenyl-95% methylpolysiloxane, 14% cyanopropyl-86% polysiloxane, and polyethylene glycol, on different complexity samples, including standard mixtures of volatile suspected allergens and pesticides, and cornmint and vetiver essential oils. The results show that IL columns can successfully be used for a wide range of applications characteristic of these fields, mainly because of their unusual selectivity, in particular when separations based on functional groups are required. Moreover, the latest generation of IL columns (IL61 and IL60) presents chromatographic performance comparable to or only slightly lower than that of the conventional columns routinely used in these fields. PMID:23122273

Cagliero, Cecilia; Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Sgorbini, Barbara; Rubiolo, Patrizia

2012-10-17

101

A kinetic study of the reaction between N,N-dimethyl-p-toluidine and its electrogenerated radical cation in a room temperature ionic liquid.  

PubMed

The reaction between N,N-dimethyl-p-toluidine (DMT) and the radical cation generated through its one-electron oxidation has been studied electrochemically in the room temperature ionic liquid N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [Py14][NTf2]. Kinetic information obtained as linear sweep and cyclic voltammetry collected at 5 microm, 10 microm and 0.3 mm diameter platinum disk electrodes over a range of initial substrate concentrations and scan rates spanning five orders of magnitude was complemented by chronoamperometric measurements designed to probe the rate of diffusion. At the fastest scan rates the homogeneous reactions following the initial electron transfer were effectively out-run, facilitating an assessment of the electrode kinetics using DIGISIM and a validated Nicholson's method. Through digital simulation the voltammetry was then shown to be consistent with a mechanism established for the same reaction in acetonitrile, involving dimerisation of the DMT radicals following an initial and rate-determining proton transfer step. After careful consideration of all parameters, a bimolecular rate constant of (3.4 +/- 1.1) x 10(2) dm3 mol(-1) s(-1) was deduced by fitting the data. This was compared to the equivalent value for acetonitrile and, in light of this, the implications on the viability of ionic liquids for use as alternative mainstream solvents briefly assessed. PMID:16463338

Evans, Russell G; Compton, Richard G

2006-02-13

102

Quaternary ammonium room-temperature ionic liquid including an oxygen atom in side chain/lithium salt binary electrolytes: ab initio molecular orbital calculations of interactions between ions.  

PubMed

Interactions of the lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) complex with N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium (DEME), 1-ethyl-3-methylimidazolium (EMIM) cations, neutral diethylether (DEE), and the DEMETFSA complex were studied by ab initio molecular orbital calculations. An interaction energy potential calculated for the DEME cation with the LiTFSA complex has a minimum when the Li atom has contact with the oxygen atom of DEME cation, while potentials for the EMIM cation with the LiTFSA complex are always repulsive. The MP2/6-311G**//HF/6-311G** level interaction energy calculated for the DEME cation with the LiTFSA complex was -18.4 kcal/mol. The interaction energy for the neutral DEE with the LiTFSA complex was larger (-21.1 kcal/mol). The interaction energy for the DEMETFSA complex with LiTFSA complex is greater (-23.2 kcal/mol). The electrostatic and induction interactions are the major source of the attraction in the two systems. The substantial attraction between the DEME cation and the LiTFSA complex suggests that the interaction between the Li cation and the oxygen atom of DEME cation plays important roles in determining the mobility of the Li cation in DEME-based room temperature ionic liquids. PMID:18636771

Tsuzuki, Seiji; Hayamizu, Kikuko; Seki, Shiro; Ohno, Yasutaka; Kobayashi, Yo; Miyashiro, Hajime

2008-07-18

103

Fabrication of molecularly imprinted hybrid monoliths via a room temperature ionic liquid-mediated nonhydrolytic sol-gel route for chiral separation of zolmitriptan by capillary electrochromatography.  

PubMed

A room temperature ionic liquid (RTIL)-mediated nonhydrolytic sol-gel (NHSG) protocol was explored for the fabrication of new molecularly imprinted silica-based hybrid monoliths for chiral separation of a basic template zolmitriptan by CEC. The RTIL-mediated NHSG protocol involved free-radical copolymerization and NHSG process. Three carboxylic acids (trifluoromethyl acrylic acid, cinnamic acid, and methacrylic acid (MAA)) were examined as both the functional monomers and the catalysts for the NHSG condensation of methacryloxypropyltrimethoxysilane (MPTMS) to form silica-based framework. RTIL was incorporated to reduce gel shrinkage and also to act as the pore template. The effects of carboxylic acids and RTIL on the performance of the silica-based hybrid molecularly imprinted polymer (MIP) monoliths were investigated in detail to realize excellent chiral recognition and to give new insights into the mechanism of the RTIL-mediated NHSG strategy. Excellent chiral separation of (R)/(S)-zolmitriptan was achieved when the molar ratio of MAA to MPTMS was 1:4 and 1:2 with RTIL involved. The synergism of the free-radical copolymerization of the C=C bond of carboxylic acids and MPTMS with the NHSG condensation of MPTMS catalyzed by the carboxylic acids was demonstrated. The incorporation of RTIL increased porosity, and hence improved selectivity of the prepared hybrid monoliths. PMID:18203253

Wang, He-Fang; Zhu, Yi-Zhou; Lin, Jian-Ping; Yan, Xiu-Ping

2008-02-01

104

Study of the translational diffusion of the benzophenone ketyl radical in comparison with stable molecules in room temperature ionic liquids by transient grating spectroscopy  

SciTech Connect

Transient grating (TG) spectroscopy has been applied to the photoinduced hydrogen-abstraction reaction of benzophenone (BP) in various kinds of room temperature ionic liquids (RTILs). After the photoexcitation of BP in RTILs, the formation of a benzophenone ketyl radical (BPK) was confirmed by the transient absorption method, and the TG signal was analyzed to determine the diffusion coefficients of BPK and BP. For comparison, diffusion coefficients of carbon monoxide (CO), diphenylacetylene (DPA), and diphenylcyclopropenone (DPCP) in various RTILs were determined by the TG method using the photodissociation reaction of DPCP. While the diffusion coefficients of the stable molecules BP, DPA, and DPCP were always larger than those predicted by the Stokes-Einstein (SE) relation in RTILs, that of BPK was much smaller than those of the stable molecules and relatively close to that predicted by the SE relation in all solvents. For the smallest molecule CO, the deviation from the SE relation was evident. The diffusion coefficients of stable molecules are better represented by a power law of the inverse of the viscosity when the exponent was less than unity. The ratios of the diffusion coefficient of BP to that of BPK were larger in RTILs (2.7-4.0) than those (1.4-2.3) in conventional organic solvents. The slow diffusion of BPK in RTILs was discussed in terms of the fluctuation of the local electric field produced by the surrounding solvent ions.

Nishiyama, Y.; Fukuda, M.; Terazima, M.; Kimura, Y. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

2008-04-28

105

Electrodeposition of aluminium and aluminium-copper alloys from a room temperature ionic liquid electrolyte containing aluminium chloride and triethylamine hydrochloride  

NASA Astrophysics Data System (ADS)

The electrodeposition of Al and Al-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing AlCl3-Et3NHCl was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry (CV), and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Al of 70 ?m in thickness and an Al-Cu alloy of 30 ?m in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the Al deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be (30 ± 5) and (29 ± 5) nm, respectively, for Al and Al-Cu alloys. Potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopic (EIS) measurements showed that Al-Cu alloys are more corrosion resistant than Al.

Suneesh, P. V.; Satheesh Babu, T. G.; Ramachandran, T.

2013-09-01

106

Determination of the hydrogen-bonding induced local viscosity enhancement in room temperature ionic liquids via femtosecond time-resolved depleted spontaneous emission.  

PubMed

The fluorescence depletion dynamics of Rhodamine 700 (R-700) molecules in room temperature ionic liquids (RTILs) 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF(4)]) and 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate ([HOemim][BF(4)]) were investigated to determine the local viscosity of the microenvironment surrounding the fluorescent molecules, which is induced by strong hydrogen bonding interaction between cationic and anionic components in RTILs. The solvation and rotation dynamics of R-700 molecules in RTILs show slower time constants relative to that in conventional protic solvents with the same bulk viscosity, indicating that the probe molecule is facing a more viscous microenvironment in RTILs than in conventional solvents because of the strong hydrogen bonding interaction between cationic and anionic components. In addition, this effect is more pronounced in hydroxyl-functionalized ionic liquid than in the regular RTIL due to the presence of a hydroxyl group as a strong hydrogen bonding donor. The hydrogen-bonding-induced local viscosity enhancement effect related to the heterogeneity character of RTILs is confirmed by the nonexponential rotational relaxation of R-700 determined by time-correlated single photon counting (TCSPC). The geometry of hydrogen bonding complexes with different components and sizes are further optimized by density functional theory methods to show the possible hydrogen-bond networks. A model of the hydrogen-bonding network in RTILs is further proposed to interpret the observed specific solvation and local viscosity enhancement effect in RTILs, where most of the fluoroprobes exist as the free nonbonding species in the RTIL solutions and are surrounded by the hydrogen-bonding network formed by the strong hydrogen-bonding between the cationic and anionic components in RTIL. The optimized geometry of hydrogen bonding complexes with different components and sizes by density functional theory methods confirms the local viscosity enhancement effect deduced from fluorescence depletion and TCSPC experiments. The calculated interaction energies reveal the existence of the stronger hydrogen bonding network in RTILs (especially in hydroxyl-functionalized ionic liquid) than that in conventional protic solvent, which leads to the enhancement effect of local microviscosity, and therefore leads to the slow solvation and rotation dynamics of probe molecules observed in RTILs. PMID:21648476

Ma, Xiaonan; Yan, Linyin; Wang, Xuefei; Guo, Qianjin; Xia, And Andong

2011-06-21

107

Supported Phospholipid Bilayer Interaction with Components Found in Typical Room-Temperature Ionic Liquids - a QCM-D and AFM Study †  

PubMed Central

Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM+) was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer) and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonyl)imide (Tf2N-) was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-Tf2N) formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer.

Evans, Kervin O.

2008-01-01

108

An efficient ultrasound assisted approach for the impregnation of room temperature ionic liquid onto Dowex 1×8 resin matrix and its application toward the enhanced adsorption of chromium (VI).  

PubMed

The work discussed in this paper is based on the utilization of ultrasound in conjunction with an ionic liquid (Aliquat 336) impregnated Dowex 1×8 resin for the effective adsorption of chromium. Ionic liquids are known for their selectivity toward metal extraction and ultrasonic medium offers efficient energy transfer for impregnating the ionic liquid in the resin matrix. The molecular interaction between the ionic liquid impregnated resin and chromium was studied through various physicochemical and spectroscopic techniques. The influence of various analytical parameters on the adsorption of Cr(VI) such as pH, adsorbent dosage, temperature and interference of foreign ions was studied in detail. Chromium (VI) was quantitatively adsorbed in the pH range of 3.5-4, with a high adsorption capacity of 230.9 mg g(-1) in conformity with the Langmuir isotherm model. The study of thermodynamic parameters showed that the adsorption process is exothermic and spontaneous. The adsorbent could be regenerated using 1 mol L(-1) HCl-0.28 mol L(-1) ascorbic acid mixture. Chromium could be effectively detoxified from an industrial effluent and finally the developed method was validated with the analysis of a certified reference material (BCR-715). The obtained results indicated that the ultrasonic assisted impregnation of the room temperature ionic liquid significantly enhances and improves the removal efficiency of Cr(VI). PMID:22365143

Kalidhasan, S; Kumar, A Santhana Krishna; Rajesh, Vidya; Rajesh, N

2012-02-06

109

Use of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids as chelate extraction solvent with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione  

Microsoft Academic Search

Possible use of room temperature ionic liquids (RTILs) as chelate extraction solvent was evaluated by using 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF6]). These RTILs showed high extraction performance for divalent metal cations with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta). The extracted metals were back-extracted into 1moldm?3 nitric acid quantitatively. Furthermore, the extracted species were estimated as neutral hydrated complexes M(tta)2(H2O)n

Naoki Hirayama; Mika Deguchi; Hitomi Kawasumi; Takaharu Honjo

2005-01-01

110

Photoinduced electron transfer (PET) from N, N-dimethylaniline to 7-amino Coumarin dyes in a room temperature ionic liquid (RTIL): Slowing down of electron transfer rate compared to conventional solvent  

NASA Astrophysics Data System (ADS)

In this Letter we have investigated the photoinduced electron transfer (PET) in a protic room temperature ionic liquid (PRTIL) comprised of non-aromatic cation and anion, N, N-dimethyl ethanol ammonium formate (DAF) to investigate how the dynamics of PET is affected in RTIL compared to other solvents. The photoinduced electron transfer rate in the ionic liquid DAF decreases by an order of magnitude upon going from the conventional solvent acetonitrile. We have observed saturation, i.e., a Rehm-Weller type of behaviour in the electron transfer rate. The ET rate ( k q) vs. -?G 0 plot shows saturation to a diffusion-controlled value at the higher exergonicity region.

Sarkar, Souravi; Pramanik, Rajib; Seth, Debabrata; Setua, Palash; Sarkar, Nilmoni

2009-07-01

111

Extraction and separation of thorium(IV) from lanthanides(III) with room-temperature ionic liquids containing primary amine N{sub 1923}  

SciTech Connect

The extraction behavior of Th(IV) by primary amine N{sub 1923} in imidazolium-based ionic liquid namely 1-octyl-3-methylimidazolium hexafluorophosphate (N{sub 1923}/IL) was studied in this paper. Results showed that N{sub 1923}/IL had poorer extraction ability for Th(IV) than N{sub 1923} in n-heptane (N{sub 1923}/HEP). The separation coefficients between Th(IV) and lanthanides(III) ({beta}{sub Th/Ln}) were obtained and compared with those in the N{sub 1923}/HEP system. On this basis, we made a preliminary assessment for the possibility of using ionic liquids as solvents for the separation of Th(IV) from lanthanides(III) sulfate in a clean process. (authors)

Zuo, Y. [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing (China); Chen, J.; Bai, Y.; Li, D.Q. [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

2008-07-01

112

Room-temperature ionic liquids as electrolytes in electroanalytical determination of traces of 2-furaldehyde from oil and related wastewaters from refining processes.  

PubMed

Three different ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMIM][BF(4)]; 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [BMIM][OTf]; and 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide [bmpyrr][NTf(2)] were studied as electrolytes in the electroanalytical quantification of 2-furaldehyde using square wave and differential pulse voltammetries. On applying a cathodic scan, a well-defined 2-electron wave was observed corresponding to the reduction of 2-furaldehyde to furfuryl alcohol. The electrochemical stability of the ionic liquids as electrolytes for analytical aspects and electrokinetic studies was investigated using a glassy carbon electrode (GCE). The measurements were carried out in a designed double-wall three-electrode cell, using two platinum wires as the quasi-reference and counter electrodes. Differential pulse voltammetry was found to be the most sensitive method at GCE. The detection limits of 1.4, 19.0 and 2.5 microg g(-1) were obtained for the determination of 2-furaldehyde in [EMIM][BF(4)], [BMIM][OTf] and [BMPyrr][NTf(2)], respectively. At a concentration of 50 microg g(-1), the maximum relative standard deviation (n=3) was 4.9%. The effect of water content of the ionic liquids on their potential windows and waveforms was also investigated. The proposed method was successfully applied to the determination of 2-furaldehyde in real samples, especially in oil matrices. PMID:20188895

Shamsipur, Mojtaba; Beigi, Ali Akbar Miran; Teymouri, Mohammad; Ghorbani, Yousefali; Irandoust, Mohsen; Mehdizadeh, Ali

2009-12-03

113

Biocatalytic transformations in ionic liquids  

Microsoft Academic Search

Room temperature ionic liquids are non-volatile, thermally stable and highly polar; they are also moderately hydrophilic solvents. Here, we discuss their use as reaction media for biocatalysis. Enzymes of widely diverging types are catalytically active in ionic liquids or aqueous biphasic ionic liquid systems. Lipases, in particular, maintain their activity in anhydrous ionic liquid media; the (enantio)selectivity and operational stability

Fred van Rantwijk; Rute Madeira Lau; Roger A Sheldon

2003-01-01

114

A molecular dynamics simulation study of the electric double layer and capacitance of [BMIM][PF6] and [BMIM][BF4] room temperature ionic liquids near charged surfaces.  

PubMed

A molecular dynamics simulation study of electric double layer (EDL) structure and differential capacitance (DC) of two 1-butyl-3-methylimidazolium (BMIM)-based room temperature ionic liquids, i.e. [BMIM][BF4] and [BMIM][PF6], has been conducted on basal and prismatic graphite as well as (001) and (011) gold electrode surfaces. The influence of the electrode surface and electrolyte structure on electrode capacitance and EDL structure are discussed. For a given electrode surface both the [BMIM][BF4] and [BMIM][PF6] electrolytes generate very similar DC and EDL structures. The DC for these ionic liquids in contact with atomically flat surfaces (i.e. basal graphite and (001)Au) shows very small variations within the electrolyte chemical stability potential window and fluctuates around an average value of ?5 ?F cm(-2). On atomically more corrugated surfaces (i.e., Au(011) and prismatic graphite) the DC shows more variation with electrode potential and depends on the correspondence between dimensions of the surface roughness and electrolyte ion sizes. The trends and dependencies obtained for DC are used to discriminate between mutually contradictory experimental data reported in the literature for related systems. PMID:23873305

Hu, Zongzhi; Vatamanu, Jenel; Borodin, Oleg; Bedrov, Dmitry

2013-07-22

115

Direct electrochemistry and electrocatalysis of heme proteins immobilised in carbon-coated nickel magnetic nanoparticle-chitosan-dimethylformamide composite films in room-temperature ionic liquids.  

PubMed

The direct electrochemistry and electrocatalysis of heme proteins entrapped in carbon-coated nickel magnetic nanoparticle-chitosan-dimethylformamide (CNN-CS-DMF) composite films were investigated in the hydrophilic ionic liquid [bmim][BF4]. The surface morphologies of a representative set of films were characterised via scanning electron microscopy. The proteins immobilised in the composite films were shown to retain their native secondary structure using UV-vis spectroscopy. The electrochemical performance of the heme proteins-CNN-CS-DMF films was evaluated via cyclic voltammetry and chronoamperometry. A pair of stable and well-defined redox peaks was observed for the heme protein films at formal potentials of -0.151V (HRP), -0.167V (Hb), -0.155V (Mb) and -0.193V (Cyt c) in [bmim][BF4]. Moreover, several electrochemical parameters of the heme proteins were calculated by nonlinear regression analysis of the square-wave voltammetry. The addition of CNN significantly enhanced not only the electron transfer of the heme proteins but also their electrocatalytic activity toward the reduction of H2O2. Low apparent Michaelis-Menten constants were obtained for the heme protein-CNN-CS-DMF films, demonstrating that the biosensors have a high affinity for H2O2. In addition, the resulting electrodes displayed a low detection limit and improved sensitivity for detecting H2O2, which indicates that the biocomposite film can serve as a platform for constructing new non-aqueous biosensors for real detection. PMID:23632434

Wang, Ting; Wang, Lu; Tu, Jiaojiao; Xiong, Huayu; Wang, Shengfu

2013-04-12

116

EQCM study of the [Au(III)Cl4](-)-[Au(I)Cl2](-)-Au(0) redox system in 1-ethyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquid.  

PubMed

The electrochemical behavior of the [Au(III)Cl(4)](-)-[Au(I)Cl(2)](-)-Au(0) redox system in room temperature ionic liquid (RTIL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF(4)) has been investigated quantitatively using an in situ electrochemical quartz crystal microbalance (EQCM) technique based on a Pt film-coated quartz crystal electrode (Pt-QCE). A series of two-electron (2e) and one-electron (1e) reductions of the [Au(III)Cl(4)](-) to [Au(I)Cl(2)](-) and [Au(I)Cl(2)](-) to Au metal were recognized at the Pt surface. Besides, the disproportionation reaction of [Au(I)Cl(2)](-) (i.e., the 2e-reduction product of [Au(III)Cl(4)](-)) to [Au(III)Cl(4)](-) and Au metal was also observed. Electro-dissolution of the Au deposited on the Pt electrode through a 1e-oxidation reaction in the presence of chloride ions was also confirmed using the Pt-QCE based EQCM technique. A 2e-oxidation reaction of [Au(I)Cl(2)](-) (i.e., the dissolved product) to [Au(III)Cl(4)](-) along with the oxidation of Cl(-) ion on the Pt surface was also realized at high anodic potential. The results demonstrate that in situ EQCM technique is applicable and powerful in elucidating electrochemical surface phenomena accompanying a mass change in RTIL. PMID:20163082

Oyama, Taku; Yamaguchi, Shuichiro; Rahman, Mohammad Rezaur; Okajima, Takeyoshi; Ohsaka, Takeo; Oyama, Noboru

2010-06-01

117

Spectroscopic and electrochemical studies of U(IV)-hexachloro complexes in hydrophobic room-temperature ionic liquids [BuMeIm][Tf2N] and [MeBu3N][Tf2N].  

PubMed

The behavior of U(IV) octahedral complexes [cation]2[UCl6], where the [cation]+ is [BuMeIm]+ and [MeBu3N]+, is studied using UV/visible spectroscopy, cyclic staircase voltammetry, and rotating disk electrode voltammetry in hydrophobic room-temperature ionic liquids (RTILs) [BuMeIm][Tf2N] and [MeBu3N][Tf2N], where BuMeIm+ and MeBu3N+ are 1-butyl-3-methylimidazolium and tri-n-butylmethylammonium cations, respectively, and Tf2N- is the bis(trifluoromethylsulfonyl)imide anion. The absorption spectra of [cation]2[UCl6] complexes in the RTIL solutions are similar to the diffuse solid-state reflectance spectra of the corresponding solid species, indicating that the octahedral complex UCl6(2-) is the predominant chemical form of U(IV) in Tf2N--based hydrophobic ionic liquids. Hexachloro complexes of U(IV) are stable to hydrolysis in the studied RTILs. Voltammograms of UCl(6)2- at the glassy carbon electrode in both RTILs and at the potential range of -2.5 to +1.0 V versus Ag/Ag(I) reveal the following electrochemical couples: UCl6-/UCl6(2-) (quasi-reversible system), UCl(6)2-/UCl6(3-) (quasi-reversible system), and UCl(6)2-/UCl6(Tf2N)x-3+x (irreversible reduction). The voltammetric half-wave potential, Ep/2, of the U(V)/U(IV) couple in [BuMeIm][Tf2N] is positively shifted by 80 mV compared with that in [MeBu3N][Tf2N]. The positive shift in the Ep/2 value for the quasi-reversible U(IV)/U(III) couple is much greater (250 mV) in [BuMeIm][Tf2N]. Presumably, the potential shift is due to the specific interaction of BuMeIm+ with the uranium-hexachloro complex in ionic liquid. Scanning the negative potential to -3.5 V in [MeBu3N][Tf2N] solutions of UCl6(2-) reveals the presence of an irreversible cathodic process at the peak potential equal to -3.12 V (at 100 mV/s and 60 degrees C), which could be attributed to the reduction of U(III) to U(0). PMID:16323937

Nikitenko, S I; Cannes, C; Le Naour, C; Moisy, P; Trubert, D

2005-12-12

118

Synthesis of ionic liquids  

DOEpatents

Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

2008-09-09

119

Synthesis of ionic liquids  

DOEpatents

Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

2011-11-01

120

Room-temperature silver-containing liquid metal salts with nitrate anions.  

PubMed

The synthesis, structural, thermal and electrochemical properties of fluorine-free silver-containing ionic liquids are presented. The ionic liquid cations are formed by a silver(i) ion surrounded by two 1-alkylimidazole ligands, with the counter anions being nitrate ions. Depending on the alkyl chain length, the complexes were found to be liquids at room temperature or melting slightly above this. For the solid compounds it was possible to elucidate the structure by single crystal X-ray analysis. The ionic liquids are electroactive, have good mass transport properties and can be used for the electrodeposition of silver at high current densities. The thermal properties and stability of these compounds were tested by differential scanning calorimetry and thermogravimetric analysis. The viscosity of the ionic liquids follows a Vogel-Tamman-Fulcher relationship as a function of temperature. The electrochemical properties of the complexes were tested by cyclic voltammetry and the resulting electrodeposits were examined using scanning electron microscopy and atomic force microscopy. PMID:24097139

Schaltin, Stijn; Brooks, Neil R; Sniekers, Jeroen; Depuydt, Daphne; Van Meervelt, Luc; Binnemans, Koen; Fransaer, Jan

2013-10-16

121

Ignition of Ionic Liquids. Volume 2.  

National Technical Information Service (NTIS)

This report summarizes the experimental and theoretical research effort undertaken to study and identify some of the chemical pathways involved in the hypergolic ignition of mixtures consisting of room temperature ionic liquids (ILs) and suitable oxidizer...

G. Vaghjiani S. Chambreau

2010-01-01

122

Room temperature single-photon Source:Single-dye molecule fluorescence in Liquid Crystal host  

Microsoft Academic Search

We report on new approaches toward an implementation of an efficient, room temperature, deterministically polarized, single-photon source (SPS) on demand-a key hardware element for quantum information and quantum communication. Operation of a room temperature SPS is demonstrated via photon antibunching in the fluorescence from single terrylene-dye molecules embedded in a cholesteric liquid crystal host. Using oxygen-depleted liquid crystal hosts, dye-bleaching

Svetlana G. Lukishova; Ansgar W. Schmid; Andrew J. McNamara; Robert W. Boyd; Carlos R. Stroud

2003-01-01

123

Uranyl complexation by chloride ions. Formation of a tetrachlorouranium(VI) complex in room temperature ionic liquids [Bmim][Tf2N] and [MeBu3N][Tf2N].  

PubMed

The tetrachlorouranium(VI) complex is formed in [Bmim][Tf2N] and [MeBu3N][Tf2N] from a uranium(VI) solution in the presence of a stoichiometric quantity of chloride ions. The [UVIO2Cl4]2- absorption and emission spectra show bands splitting in comparison with the [UVIO2]2+ spectra, as observed in the solid state, organic solvents, and chloroaluminate-based ionic liquids. The fluorescence lifetime of [UO2Cl4]2- in [MeBu3N][Tf2N] is 0.7 +/- 0.1 mus. The reduction potential of this complex is -1.44 and -1.8 V vs Ag/Ag+ respectively in [Bmim][Tf2N] and [MeBu3N][Tf2N] and does not depend on the chloride concentration. The mechanism proposed for the redox process is a monoelectronic reduction to form [UVO2Cl4]3-, followed by a chemical reaction. The tetrachlorouranium(V) complex seems more stable in [Bmim][Tf2N] than in [MeBu3N][Tf2N]. The electrochemical analysis put in evidence specific interactions of the ionic liquid cation with the uranium anionic species. PMID:17173389

Sornein, M-O; Cannes, C; Le Naour, C; Lagarde, G; Simoni, E; Berthet, J-C

2006-12-25

124

Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanché batteries  

Microsoft Academic Search

A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3

M. P. Stracke; M. V. Migliorini; E. Lissner; H. S. Schrekker; J. Dupont; R. S. Gonçalves

2009-01-01

125

Room temperature phosphorescence in the liquid state as a tool in analytical chemistry  

Microsoft Academic Search

A wide-ranging overview of room temperature phosphorescence in the liquid state (RTPL1Although the abbreviation RTPL is frequently used in the literature, the specific RTPL techniques are generally designated by RTP, for instance, CD-RTP. Therefore, in the introductory sections the term RTPL will be used, while in the sections on the specific techniques the term RTP will be applied.1) is presented,

Jacobus Kuijt; Freek Ariese; Udo A. Th. Brinkman; Cees Gooijer

2003-01-01

126

Knoevenagel Condensation of Aldehydes with Meldrum's Acid in Ionic Liquids  

Microsoft Academic Search

The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in the recyclable ionic liquid [bmim]BF4 at room temperature in the presence of catalytic amounts of piperidine.

Daryoush Tahmassebi; Levi J. A. Wilson; Jerod M. Kieser

2009-01-01

127

Nanostructural organization in ionic liquids.  

PubMed

Nanometer-scale structuring in room-temperature ionic liquids is observed using molecular simulation. The ionic liquids studied belong to the 1-alkyl-3-methylimidazolium family with hexafluorophosphate or with bis(trifluoromethanesulfonyl)amide as the anions, [C(n)mim][PF(6)] or [C(n)mim][(CF(3)SO(2))(2)N], respectively. They were represented, for the first time in a simulation study focusing on long-range structures, by an all-atom force field of the AMBER/OPLS_AA family containing parameters developed specifically for these compounds. For ionic liquids with alkyl side chains longer than or equal to C(4), aggregation of the alkyl chains in nonpolar domains is observed. These domains permeate a tridimensional network of ionic channels formed by anions and by the imidazolium rings of the cations. The nanostructures can be visualized in a conspicuous way simply by color coding the two types of domains (in this work, we chose red = polar and green = nonpolar). As the length of the alkyl chain increases, the nonpolar domains become larger and more connected and cause swelling of the ionic network, in a manner analogous to systems exhibiting microphase separation. The consequences of these nanostructural features on the properties of the ionic liquids are analyzed. PMID:16494347

Canongia Lopes, José N A; Pádua, Agílio A H

2006-02-23

128

Harvesting low grade heat to generate electricity with thermosyphon effect of room temperature liquid metal  

NASA Astrophysics Data System (ADS)

Based on thermosyphon effect of room temperature liquid metal, a technical strategy of harvesting low grade heat to generate electricity was proposed. A conceptual system was constructed and an open circuit voltage of 2.62 V with an electrical output power of 110 mW was yielded when the heating power was 45.6 W. This method resolves the difficulty of installing an electric generator in confined space and significantly enlarges the area for converting heat to electricity. Due to its simplicity, avoidance of moving parts, wide working temperature range, and self powering feature, this electric generation system is extremely reliable, completely silent, and flexible.

Li, Peipei; Liu, Jing

2011-08-01

129

Liquid crystalline texture in glycine-modified diacetylene Langmuir monolayers at room temperature  

SciTech Connect

Direct visualization of the self-assembling and liquid crystalline texture formation in glycine-modified diacetylene (Gly-DA) Langmuir monolayers at room temperature is achieved using Brewster angle microscopy (BAM). The striped (smectic) texture appears directly after spreading the monolayer at the air-water interface The spatial period of this texture has been estimated to be in the range 0.015-0.005 mm, which is in agreement with the range predicted theoretically for this phase. When pressure is applied, the width of the strips decreases and, finally, the striped texture disappears. Another texture appears in the pressure range 30-35 mN/m: the well-defined pseudo-focal-conic texture, which points to a disordered hexagonal columnar mesophase. In addition, direct visualization of the Gly-DA polymerization under UV radiation exposure via BAM is achieved. We observe focal-conic texture reminiscent of smectic C phase. 18 refs., 3 figs.

Litvin, A.L. (U.S. Army Natick Research, Development Engineering Center, MA (United States) Geo-Centers, Inc., Natick, MA (United States)); Samuelson, L.A.; Kaplan, D.L. (U.S. Army Natick Research, Development Engineering Center, MA (United States)); Spevak, W.; Charych, D.H. (Lawrence Berkeley Lab., CA (United States))

1995-01-12

130

Mixtures of ionic liquids.  

PubMed

Simple ionic liquids have long been held to be designer solvents, based upon the ability to independently vary their cations and anions. The formation of mixtures of ionic liquids increases this synthetic flexibility. We review the available literature of these ionic liquid mixtures to identify how their properties change and the possibility for their application. PMID:22890419

Niedermeyer, Heiko; Hallett, Jason P; Villar-Garcia, Ignacio J; Hunt, Patricia A; Welton, Tom

2012-12-01

131

Use of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate in countercurrent chromatography  

Microsoft Academic Search

Room temperature ionic liquids (RTIL) are molten salts that are liquids at room temperature. Their liquid state makes them possible candidates as solvents in countercurrent chromatography (CCC), which uses solvents as both the mobile and stationary phases. The study focuses on 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF 6), an easy to synthesize and purify RTIL whose melting point is ?8°C. It is

A. Berthod; S. Carda-Broch

2004-01-01

132

Toxicity of imidazolium ionic liquids to freshwater algae  

Microsoft Academic Search

Room-temperature ionic liquids (ILs) are a class of novel green chemicals being designed to replace traditional volatile organic solvents in industrial processes. The potential effects of ILs on aquatic ecosystems have been poorly studied, despite the possibility of unintentional discharge into rivers and lakes, and their intentional disposal in wastewater treatment plants. We studied the effects of three imidazolium ionic

Konrad J. Kulacki; Gary A. Lamberti

2008-01-01

133

Novel room temperature molten salt electrolyte based on LiTFSI and acetamide for lithium batteries  

Microsoft Academic Search

A novel room temperature molten salt (RTMS) electrolyte composed of lithium bis(trifluoromethane sulfone)imide (LiN(SO2CF3)2, LiTFSI) and acetamide was found. Both LiTFSI and acetamide are solid at room temperature, but their mixture is a liquid at room temperature with a eutectic temperature of ?67 °C at a molar ratio of 1:4 (LiTFSI:Acetamide). The room temperature ionic conductivities of some compositions of

Yongsheng Hu; Hong Li; Xuejie Huang; Liquan Chen

2004-01-01

134

Use of ionic liquids as coordination ligands for organometallic catalysts  

DOEpatents

Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

Li, Zaiwei (Moreno Valley, CA); Tang, Yongchun (Walnut, CA); Cheng; Jihong (Arcadia, CA)

2009-11-10

135

How to separate ionic liquids: Use of Hydrophilic Interaction Liquid Chromatography and mixed mode phases  

Microsoft Academic Search

This chromatographic study deals with the development of a convenient and versatile method to separate Room Temperature Ionic Liquids. Different modes of chromatography were studied. The study attempts to answer the following question: “what were the most important interactions for the separation of ionic liquids?”. The results show that the essential interactions to assure a good retention of RTILs are

C. Lamouroux; G. Foglia; G. Le Rouzo

2011-01-01

136

Direct Writing of Flexible Electronics through Room Temperature Liquid Metal Ink  

PubMed Central

Background Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn10-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. Methods The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. Results The electrical resistivity of the fluid like GaIn10-based material was measured as 34.5 µ?·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED) array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. Conclusions The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn10-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized purpose and can be extended to more industrial areas, even daily life.

Gao, Yunxia; Li, Haiyan; Liu, Jing

2012-01-01

137

Ionic liquid based dispersive liquid–liquid microextraction for the extraction of pesticides from bananas  

Microsoft Academic Search

This paper describes a dispersive liquid–liquid microextraction (DLLME) procedure using room temperature ionic liquids (RTILs) coupled to high-performance liquid chromatography with diode array detection capable of quantifying trace amounts of eight pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox and fenazaquin) in bananas. Fruit samples were first homogenized and extracted (1g) with acetonitrile and after suitable evaporation and reconstitution

Lidia M. Ravelo-Pérez; Javier Hernández-Borges; María Asensio-Ramos; Miguel Ángel Rodríguez-Delgado

2009-01-01

138

Pesticide extraction from table grapes and plums using ionic liquid based dispersive liquid–liquid microextraction  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) have been used as extraction solvents in dispersive liquid–liquid microextraction (DLLME)\\u000a for the determination of eight multi-class pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione,\\u000a oxyfluorfen, hexythiazox, and fenazaquin) in table grapes and plums. The developed method involves the combination of DLLME\\u000a and high-performance liquid chromatography with diode array detection. Samples were first homogenized and extracted

Lidia M. Ravelo-Pérez; Javier Hernández-Borges; Antonio V. Herrera-Herrera; Miguel Ángel Rodríguez-Delgado

2009-01-01

139

Sulfonium-based Ionic Liquids Incorporating the Allyl Functionality  

PubMed Central

A series of sulfonium halides bearing allyl groups have been prepared and characterized. Anion metathesis with Li[Tf2N] and Ag[N(CN)2] resulted in sulfonium-based ionic liquids which exhibit low viscosities at room temperature. The solid state structure of one of the halide salts was determined by single crystal X-ray diffraction.

Zhao, Dongbin; Fei, Zhaofu; Ang, Wee Han; Dyson, Paul J.

2007-01-01

140

Applications of ionic liquids.  

PubMed

Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

Patel, Divia Dinesh; Lee, Jong-Min

2012-06-18

141

Ionic liquid electrolyte  

US Patent & Trademark Office Database

The present invention relates to electrolytes comprising tetracyanoborate and an organic cation as components of electrolytes in electrochemical and/or optoelectronic devices, in particular solar cells. This ionic liquid has low viscosity and can be used as electrolyte in the absence of a solvent. Importantly, the ionic liquid remains stable in solar cells even after prolonged thermal stress at 80.degree. C. for 1000 hours. Photovoltaic conversion efficiency remained stable and keeping more than 90% of the initial value.

2012-02-14

142

High proton polarization in crystalline naphthalene by dynamic nuclear polarization with laser excitation at room temperature and liquid nitrogen temperature  

NASA Astrophysics Data System (ADS)

We have successfully polarized protons in naphthalene doped with pentacene at room temperature and liquid nitrogen temperature. Pentacene molecules have been excited with a laser beam and protons have been polarized dynamically in the triplet state of pentacene. We have obtained a polarization of about 13% at liquid nitrogen temperature in a field of about 3 kG with an N2 laser of about 150 mW. We expect to obtain a polarization higher than 30% with another type of laser.

Iinuma, M.; Shaké, I.; Takizawa, R.; Daigo, M.; Shimizu, H. M.; Takahashi, Y.; Masaike, A.; Yabuzaki, T.

1995-02-01

143

A general design platform for ionic liquid ions based on bridged multi-heterocycles with flexible symmetry and charge.  

PubMed

A conceptual design platform for new ionic liquids with variable heterocycles, bridges, symmetry, and charge was developed using simple alkylation, click, and ionic liquid chemistries and demonstrated with 1-(2-(5-tetrazolidyl)ethyl)-3-(5-1H-tetrazolyl)methylimidazolium and its conversion into room-temperature ionic liquids as cation or as anion. PMID:20582354

Drab, David M; Shamshina, Julia L; Smiglak, Marcin; Hines, C Corey; Cordes, David B; Rogers, Robin D

2010-03-27

144

Phase-Changing Ionic Liquids: CO2 Capture with Ionic Liquids Involving Phase Change  

SciTech Connect

IMPACCT Project: Notre Dame is developing a new CO2 capture process that uses special ionic liquids (ILs) to remove CO2 from the gas exhaust of coal-fired power plants. ILs are salts that are normally liquid at room temperature, but Notre Dame has discovered a new class of ILs that are solid at room temperature and change to liquid when they bind to CO2. Upon heating, the CO2 is released for storage, and the ILs re-solidify and donate some of the heat generated in the process to facilitate further CO2 release. These new ILs can reduce the energy required to capture CO2 from the exhaust stream of a coal-fired power plant when compared to state-ofthe- art technology.

None

2010-07-01

145

Lap shear strength of selected adhesives (epoxy, varnish, B-stage glass cloth) in liquid nitrogen and at room temperature  

SciTech Connect

The adhesives included several epoxy resins, a varnish, and a B-stage glass cloth (a partially cured resin in a fiberglass cloth matrix). Several parameters critical to bond strength were varied: adhesive and adherend differences, surface preparation, coupling agents, glass cloth, epoxy thickness, fillers, and bonding pressure and temperature. The highest lap shear strengths were obtained with the B-shear glass cloth at both liquid nitrogen and room temperatures with values of approximately 20 MPa (3000 psi) and approximately 25.5 MPa (3700 psi) respectively.

Froelich, K.J.; Fitzpatrick, C.M.

1976-12-01

146

VOC and HAP recovery using ionic liquids  

SciTech Connect

During the manufacture of wood composites, paper, and to a lesser extent, lumber, large amounts of volatile organic compounds (VOCs) such as terpenes, formaldehyde, and methanol are emitted to air. Some of these compounds are hazardous air pollutants (HAPs). The air pollutants produced in the forest products industry are difficult to manage because the concentrations are very low. Presently, regenerative thermal oxidizers (RTOs and RCOs) are commonly used for the destruction of VOCs and HAPs. RTOs consume large amounts of natural gas to heat air and moisture. The combustion of natural gas generates increased CO2 and NOx, which have negative implications for global warming and air quality. The aforementioned problems are addressed by an absorption system containing a room-temperature ionic liquid (RTIL) as an absorbent. RTILs are salts, but are in liquid states at room temperature. RTILs, an emerging technology, are receiving much attention as replacements for organic solvents in industrial processes with significant cost and environmental benefits. Some of these processes include organic synthesis, extraction, and metal deposition. RTILs would be excellent absorbents for exhausts from wood products facilities because of their unique properties: no measurable vapor pressure, high solubility of wide range of organic compounds, thermal stability to 200°C (almost 400°F), and immisciblity with water. Room temperature ionic liquids were tested as possible absorbents. Four were imidizolium-based and were eight phosphonium-based. The imidizolium-based ionic liquids proved to be unstable at the conditions tested and in the presence of water. The phosphonium-based ionic liquids were stable. Most were good absorbents; however, cleaning the contaminates from the ionic liquids was problematic. This was overcome with a higher temperature (120°C) than originally proposed and a very low pressure (1 kPa. Absorption trials were conducted with tetradecy(trihexyl)phosphonium dicyanamide as the RTIL. It was determined that it has good absorption properties for methanol and ?-pinene, is thermally stable, and is relatively easy to synthesize. It has a density of 0.89 g/mL at 20°C and a molecular weight of 549.9 g/mol. Trials were conducted with a small absorption system and a larger absorption system. Methanol, formaldehyde, and other HAPs were absorbed well, nearly 100%. Acetaldehyde was difficult to capture. Total VOC capture, while satisfactory on methanol and ?-pinene in a lab system, was less than expected in the field, 60-80%. The inability to capture the broad spectrum of total organics is likely due to difficulties in cleaning them from the ionic liquid rather than the ability of the ionic liquid to absorb. It’s likely that a commercial system could be constructed to remove 90 to 100% of the gas contaminates. Selecting the correct ionic liquid would be key to this. Absorption may not be the main selection criterion, but rather how easily the ionic liquid can be cleaned is very important. The ionic liquid absorption system might work very well in a system with a limited spectrum of pollutants, such as a paint spray line, where there are not very high molecular weight, non volatile, compounds in the exhaust.

Michael R. Milota : Kaichang Li

2007-05-29

147

IONIC LIQUIDS AS MOBILE PHASE ADDITIVES IN REVERSED-PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY  

Microsoft Academic Search

Ionic liquids are compounds of salt structure with melting point below 100°C and even 25°C known as room temperature ionic liquids. They have been widely investigated as new nonmolecular solvents exhibiting a wide range of changing properties, in many fields of analytical chemistry. This work reports on the use of 1-butyl-3-methylimidazolium of varying anion chaotropicity as a mobile phase additive

J. Flieger; A. Czajkowska-?elazko

2011-01-01

148

Ionic liquid ethanol sensor.  

PubMed

Ionic liquids containing lithium methylsulfonyl group were prepared from the precursors poly(propylene glycol)-block-(ethylene glycol)-block-(propylene glycol)-bis(2-aminopropyl ether) with different molecular weight. These liquids revealed excellent electrical conductivity in the temperature range -25 to 85 degrees C. Also, they exhibited a high boiling temperature and hence a low vapor pressure in ambient condition. Additionally, they showed a high fluidity with their viscosities being comparative with that of water. To determine the sensitivity of an ethanol sensor by using these ionic liquids, these liquids were subjected into a sequential electrochemical tests with nickel electrodes which performed a high sensitivity for the ethanol sensor. It was found that only the derivative with low molecular weight could detect ethanol. Furthermore, a linear relationship between the response current and the concentration of ethanol was constructed. The detection limit was found to be 0.13% (v/v) and its response time was 336 s. PMID:15142574

Lee, Yuan Gee; Chou, Tse-Chuan

2004-07-30

149

Ionic liquid–polymer gel electrolytes from hydrophilic and hydrophobic ionic liquids 1 Presented at the Electrochemical Society Symposium: Processes in Polymers and Polymer?Metal Interfaces, Montreal, 4–9 May 1997. 1  

Microsoft Academic Search

Ionic liquid–polymer gels were prepared by incorporating hydrophilic EMIBF4 and EMI(triflate) (EMI+=1-ethyl-3-methylimidazolium) and hydrophobic BMIPF6 (BMI+=1-(1-butyl)-3-methylimidazolium) room-temperature ionic liquids into a poly(vinylidene fluoride)–hexafluoropropylene copolymer (PVdF(HFP)) matrix. Gel electrolytes prepared with ionic liquid:PVdF(HFP) mass ratios of 2:1 exhibited ionic conductivities of >10?3 S cm?1 at room temperature and >10?2 S cm?1 at 100°C. The BMIPF6-PVdF(HFP) gel was incorporated into electrochemical cells,

Joan Fuller; Amy C Breda; Richard T Carlin

1998-01-01

150

Preparation of Sm-doped ceria (SDC) nanowires and tubes by gas-liquid co-precipitation at room temperature  

SciTech Connect

Sm-doped cerium dioxide (SDC) with fcc structure was formed using a gas-liquid chemical co-precipitation process at room temperature. Morphology and structure of the as-prepared samples were characterized using TG, XRD, TEM, HRTEM and SAED techniques. Under our specific experimental conditions, two kinds of 1D nano-structures SDC have been mainly obtained. SDC nanowires are 0.3-1.2 {mu}m in lengths and 5-20 nm in diameters. SDC nanotubes have outer diameters in 10-40 nm with lengths up to 2 {mu}m. The as-prepared SDC shows very strong UV absorption ability and the maximum absorption peak redshifts compared with that of SDC nanoparticles.

Gu Lina [Department of Materials Science and Engineering, University of Science and Technology of China, 230026 Hefei (China); School of Chemistry and Chemical Engineering, Anhui University, 230039 Hefei (China)], E-mail: gln@mail.ustc.edu.cn; Meng Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China, 230026 Hefei (China)

2008-06-03

151

Application of 1-alkyl-3-methylimidazolium-based ionic liquids in non-aqueous capillary electrophoresis  

Microsoft Academic Search

In many cases salts, which are liquid at room temperature show a better solubility in organic solvents, and can be used in nonaqueous capillary zone electrophoresis as ionic additives. In this study 1-alkyl-3-methylimidasolium-based ionic liquids were used as additives in separation media to assess the interactions between the analytes and the ionic additive present and to find an influence of

M Vaher; M Koel; M Kaljurand

2002-01-01

152

Synthesis, characterization, and catalytic activity of ionic liquids based on biosources  

Microsoft Academic Search

New room-temperature ionic liquids were synthesized from natural and easily available feedstocks (choline hydroxide and amino acids) following an economical and green route in which the only by-product was water. They were successfully applied as catalysts for the Knoevenagel test reaction between benzaldehyde and different active methylene compounds, at room temperature and under solvent-free conditions, to produce ?,?-unsaturated carbonyl compounds,

P. Moriel; E. J. García-Suárez; M. Martínez; A. B. García; M. A. Montes-Morán; V. Calvino-Casilda; M. A. Bañares

2010-01-01

153

Carboxyl-functionalized task-specific ionic liquids for solubilizing metal oxides.  

PubMed

Imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, and quaternary ammonium bis(trifluoromethylsulfonyl)imide salts were functionalized with a carboxyl group. These ionic liquids are useful for the selective dissolution of metal oxides and hydroxides. Although these hydrophobic ionic liquids are immiscible with water at room temperature, several of them form a single phase with water at elevated temperatures. Phase separation occurs upon cooling. This thermomorphic behavior has been investigated by (1)H NMR, and it was found that it can be attributed to the temperature-dependent hydration and hydrogen-bond formation of the ionic liquid components. The crystal structures of four ionic liquids and five metal complexes have been determined. PMID:18841931

Nockemann, Peter; Thijs, Ben; Parac-Vogt, Tatjana N; Van Hecke, Kristof; Van Meervelt, Luc; Tinant, Bernard; Hartenbach, Ingo; Schleid, Thomas; Ngan, Vu Thi; Nguyen, Minh Tho; Binnemans, Koen

2008-10-08

154

Gas separations using non-hexafluorophosphate [PF 6] ? anion supported ionic liquid membranes  

Microsoft Academic Search

Previously, we reported on using Room temperature ionic liquids (RTILs) in place of traditional solvents for supported liquid membranes to take advantage of their unique properties. This previous work used RTILs with the hexafluorophosphate [PF6]? anion. However, the [PF6]? anion in the presence of water can break down into HF. In the current work, we studied RTIL-membranes made from the

Paul Scovazzo; Jesse Kieft; Daniel A Finan; Carl Koval; Dan DuBois; Richard Noble

2004-01-01

155

Room temperature deposition of ZnSe thin films by successive ionic layer adsorption and reaction (SILAR) method  

SciTech Connect

The zinc selenide (ZnSe) thin films are deposited onto glass substrate using relatively simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. The films are deposited using zinc acetate sodium selenosulphate precursors. The concentration, pH, immersion and rinsing times and number of immersion cycles have been optimized to obtain good quality ZnSe thin films. The X-ray diffraction (XRD) study and scanning electron microscopy (SEM) studies reveals nanocrystalline nature alongwith some amorphous phase present in ZnSe thin films. Energy dispersive X-ray (EDAX) analysis shows that the films are Se deficient. From optical absorption data, the optical band gap 'E{sub g}' for as-deposited thin film was found to be 2.8 eV and electrical resistivity in the order of 10{sup 7} {omega} cm.

Kale, R.B. [Department of Physics, Rajaram College, Kolhapur 416004, Maharashtra (India); Lokhande, C.D. [Thin Film Physics Laboratory, Department Of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India)]. E-mail: rb_kale@yahoo.co.in

2004-10-04

156

An unusual slowdown of fast diffusion in a room temperature  

SciTech Connect

Using quasielastic neutron scattering in the temperature range from 290 to 350 K, we show that the diffusive motions in a room temperature ionic liquid [H2NC(dma)2][BETI] become faster for a fraction of cations when the liquid is confined in a mesoporous carbon. This applies to both the localized and long-range translational diffusive motions of the highly mobile cations, although the former exhibit an unusual trend of slowing-down as the temperature is increased, until the localized diffusivity is reduced to the bulk ionic liquid value at a temperature of 350 K.

Chathoth, [Oak Ridge National Laboratory (ORNL); Mamontov, Eugene [ORNL; Fulvio, Pasquale F [ORNL; Wang, Xin [ORNL

2013-01-01

157

Orientational ordering of ionic liquids near a charged mica surface.  

PubMed

The self-assembly of ions in room-temperature ionic liquids adsorbed on a mica surface is studied using molecular dynamics simulations. Four liquids from the 1-methyl,n-alkylimidazolium bis(trifluoromethylsulfonyl)imide ([C(n)mim][NTf(2)]) family are investigated, where n ranges between 2 and 8. Cations with ethyl or butyl groups are found to orient with the hydrocarbon tails lying parallel to the surface, while the hexyl and octyl tails of cations are observed to be oriented perpendicular to it. The crossover in the orientational preference matches recent observations of surface forces of these liquids. PMID:22411764

Payal, Rajdeep Singh; Balasubramanian, Sundaram

2012-03-12

158

Liquid-liquid extraction of neodymium(iii) by dialkylphosphate ionic liquids from acidic medium: the importance of the ionic liquid cation.  

PubMed

The ionic liquids 1-hexyl-3-methylimidazolium bis(2-ethylhexyl)phosphate, [C6mim][DEHP], 1-hexyl-1-methylpyrrolidinium bis(2-ethylhexyl)phosphate, [C6mpyr][DEHP], and tetrabutylammonium bis(2-ethylhexyl)phosphate, [N4444][DEHP], were prepared and characterized using (1)H and (13)C NMR spectroscopy. The extraction behavior of neodymium(iii) from nitrate medium by these ionic liquids, diluted with the room temperature ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][NTf2], 1-hexyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C6mpyr][NTf2], and tributylmethylammonium bis(trifluoromethylsulfonyl)imide, [N1444][NTf2], was studied. The distribution ratio of neodymium(iii) was measured as a function of various parameters, such as pH, concentration of the ionic liquid extractant, nature of diluents, concentration of ionic liquid cations and nitrate anions in the aqueous phase. The extraction behavior was compared with that obtained for a solution of the molecular extractant bis(2-ethylhexyl)phosphoric acid (DEHPA) in an ionic liquid diluent. The extraction of neodymium(iii) in the ionic liquids [C6mim][DEHP] and [C6mpyr][DEHP] showed markedly different extraction properties in comparison with that of the quaternary ammonium analogue [N4444][DEHP], especially concerning the pH dependence of the extraction process. These results show that the extraction process can be tuned by the selection of the ionic liquid cation. The extraction experiments also included the trivalent rare-earth ions lanthanum(iii), cerium(iii), praseodymium(iii), ytterbium(iii) and yttrium(iii). Studies of the stripping behavior and the reusability of the ionic liquids were carried out, which indicate that the ionic liquids can be reused with no loss in activity. PMID:23949284

Rout, Alok; Kotlarska, Justyna; Dehaen, Wim; Binnemans, Koen

2013-08-15

159

Ionic liquid crystals of imidazolium salts with a pendant hydroxyl group  

Microsoft Academic Search

A 2-hydroxyl pendant group was anchored on the N-alkyl chain of imidazolium ionic liquid crystals. This hydroxyl group enhanced the hydrogen bonding interactions between neighboring compounds and, therefore, widened the temperature range of the mesophase, as compared to those without the hydroxyl group. Many room temperature ionic liquid crystals were formed. Polarized optical microscopy, differential scanning calorimetry, X-ray diffraction and

Josh Y. Z. Chiou; J. N. Chen; J. S. Leib; Ivan J. B. Lin

2006-01-01

160

Task-specific ionic liquid trioctylmethylammonium salicylate as extraction solvent for transition metal ions.  

PubMed

A quaternary ammonium-based room temperature ionic liquid trioctylmethylammonium salicylate (TOMAS) has been studied as an extractant of transition metal ions (Fe(3+), Cu(2+), Ni(2+), Mn(2+)) in aqueous solutions. The effect of pH value on the recovery of metal ions has been investigated. The mechanism of extraction into the ionic liquid has been proposed. The possibility of stripping voltammetric determination of transition metals in aqueous solutions using TOMAS-modified electrodes has been demonstrated. PMID:20006071

Egorov, Vladimir M; Djigailo, Dmitry I; Momotenko, Dmitry S; Chernyshov, Denis V; Torocheshnikova, Irina I; Smirnova, Svetlana V; Pletnev, Igor V

2010-01-15

161

Dialkylimidazolium ionic liquids as electrolytes for hydrogen production from water electrolysis  

Microsoft Academic Search

Imidazolium ionic liquids (ILs) such as BMI·BF4 and BMI·PF6 were studied by cyclic voltammetry (CV). BMI·BF4 was used as an electrolyte for hydrogen production through water electrolysis. The system using this ionic liquid in a conventional electrochemical cell with platinum electrodes at room temperature and atmospheric pressure gives current densities (j) higher than 20mAcm?2 and efficiencies of more than 94.5%.

Roberto F. de Souza; Janine C. Padilha; Reinaldo S. Gonçalves; Joëlle Rault-Berthelot

2006-01-01

162

Pyrrolidinium Imides: Promising Ionic Liquids for Direct Capture of Elemental Mercury from Flue Gas  

Microsoft Academic Search

A new approach to vapor phase elemental mercury capture has been explored; this approach exploits an ionic liquid coating\\u000a layer to oxidize elemental mercury for subsequent immobilization by chelating ligands. The room temperature ionic liquid 1-butyl-1-methyl\\u000a pyrrolidinium bis(trifluoromethane sulfonyl)imide (P14) was selected for study based on its oxidation potential window, thermal stability, and low vapor pressure. Tests were also\\u000a completed

Lei Ji; Stephen W. Thiel; Neville G. Pinto

2008-01-01

163

High performance fully plastic actuator based on ionic-liquid-based bucky gel  

Microsoft Academic Search

In a previous paper, we reported the first dry actuator that can be fabricated simply by layer-by-layer casting, using ‘bucky gel’, a gelatinous room-temperature ionic-liquid containing single-walled carbon nanotubes (SWNTs). Our actuator has a bimorph configuration with a polymer-supported internal ionic-liquid electrolyte layer sandwiched by two polymer-supported bucky-gel electrode layers, which allows quick and long-lived operation in air at low

Ken Mukai; Kinji Asaka; Kenji Kiyohara; Takushi Sugino; Ichiro Takeuchi; Takanori Fukushima; Takuzo Aida

2008-01-01

164

Ionic Liquids with Ammonium Cations as Lubricants or Additives  

SciTech Connect

Friction and wear are estimated to cost 6% of the US gross national product, or around $700 billion annually. A new class of more effective lubricants could lead to huge energy savings. Limited recent literature has suggested potential for using room-temperature ionic liquids as lubricants, however only a few out of millions (or more) of species have been evaluated. Recent ORNL work discovered a new category of ionic liquids with ammonium cations that have demonstrated promising lubricating properties as net lubricants or lubricant additives, particularly in lubricating difficult-to-lubricate metals like aluminum. More than 30% friction reduction has been observed on ammonium-based ionic liquids compared to conventional hydrocarbon oils. The inherent polarity of ionic liquids is believed to provide strong adhesion to contact surfaces and form a boundary lubricating film leading to friction and wear reductions. Other advantages of ionic liquids include (1) negligible volatility, (2) high thermal stability, (3) non-flammability, and (4) better intrinsic properties that eliminate the necessity of many expensive lubricant additives. With very flexible molecular structures, this new class of lubricants, particularly ammonium-based ionic liquids, can be tailored to fit a big variety of applications including but not limited to bearings, combustion engines, MEMS, and metal forming.

Qu, Jun [ORNL; Blau, Peter Julian [ORNL; Dai, Sheng [ORNL; Luo, Huimin [ORNL; Truhan, Jr., John J [ORNL

2006-01-01

165

Novel applications of ionic liquids in materials processing  

NASA Astrophysics Data System (ADS)

Ionic liquids are mixtures of organic and inorganic salts which are liquids at room temperature. Several potential applications of ionic liquids in the field of materials processing are electrowinning and electrodeposition of metals and alloys, electrolysis of active metals at low temperature, liquid-liquid extraction of metals. Results using 1-butyl-3-methylimidazolium chloride with AlCl3 at low temperatures yielded high purity aluminium deposits (>99.9% pure) and current efficiencies >98%. Titanium and aluminium were co-deposited with/without the addition of TiCl4 with up to 27 wt% Ti in the deposit with current efficiencies in the range of 78-85 %. Certain ionic liquids are potential replacements for thermal oils and molten salts as heat transfer fluids in solar energy applications due to high thermal stability, very low corrosivity and substantial sensible heat retentivity. The calculated storage densities for several chloride and fluoride ionic liquids are in the range of 160-210 MJ/m3. A 3-D mathematical model was developed to simulate the large scale electrowinning of aluminium. Since ionic liquids processing results in their low energy consumption, low pollutant emissions many more materials processing applications are expected in future.

Reddy, Ramana G.

2009-05-01

166

Liquid densities, heat capacities, refractive index and excess quantities for {protic ionic liquids + water} binary system  

Microsoft Academic Search

Densities, ?, of aqueous solutions of the room temperature protic ionic liquid (PIL), pyrrolidinium nitrate are determined at the atmospheric pressure over the temperature range from (283.15 to 323.15)K and within the whole composition range. The molar isobaric heat capacities, Cp, and refractive index, nD, of {PIL+water} binary system are measured at 298.15K. The excess molar volumes VE, excess molar

Mérièm Anouti; Magaly Caillon-Caravanier; Yosra Dridi; Johan Jacquemin; Christopher Hardacre; Daniel Lemordant

2009-01-01

167

Hydrophobic ionic liquids  

DOEpatents

Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas shown in a diagram wherein R{sub 1}, R{sub 2}, R{sub 3}, R{sub 4}, R{sub 5}, and R{sub 6} are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F-, Cl-, CF{sub 3}-, SF{sub 5}-, CF{sub 3}S-, (CF{sub 3}){sub 2}CHS- or (CF{sub 3}){sub 3}CS-; and X{sup {minus}} is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 {angstrom}{sup 3}. 4 figs.

Koch, V.R.; Nanjundiah, C.; Carlin, R.T.

1998-10-27

168

Hydrophobic ionic liquids  

DOEpatents

Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F--, Cl--, CF.sub.3 --, SF.sub.5 --, CF.sub.3 S--, (CF.sub.3).sub.2 CHS-- or (CF.sub.3).sub.3 CS--; and X.sup.- is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 .ANG..sup.3.

Koch, Victor R. (Lincoln, MA); Nanjundiah, Chenniah (Lynn, MA); Carlin, Richard T. (Nashua, NH)

1998-01-01

169

Lipase-catalysed polyester synthesis in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid  

Microsoft Academic Search

1-Butyl-3-methylimidazolium hexafluorophosphate ionic liquid was employed as a reaction medium for lipase-catalysed aliphatic polyester synthesis. Lipase PS-C exhibited excellent catalysis in polycondensation of diethyl octane-1,8-dicarboxylate and 1,4-butanediol at room temperature and at 60°C. A relatively high molecular weight polymer was obtained at 60°C.

Susheel J. Nara; Jitendra R. Harjani; Manikrao M. Salunkhe; Ankush T. Mane; Prakash P. Wadgaonkar

2003-01-01

170

Influence of chloride, water, and organic solvents on the physical properties of ionic liquids  

Microsoft Academic Search

We report here the first systematic study of the effect of impurities and additives (e.g., water, chloride, and cosolvents) on the physical properties of room-temperature ionic liquids. Remarkably, it was discovered that the viscosity of mixtures was dependent mainly on the mole fraction of added molecular solvents and only to a lesser extent upon their iden- tity, allowing viscosity changes

Kenneth R. Seddon; Annegret Stark; María-José Torres

2000-01-01

171

Ionic Liquid Membranes for Carbon Dioxide Separation  

SciTech Connect

Recent scientific studies are rapidly advancing novel technological improvements and engineering developments that demonstrate the ability to minimize, eliminate, or facilitate the removal of various contaminants and green house gas emissions in power generation. The Integrated Gasification Combined Cycle (IGCC) shows promise for carbon dioxide mitigation not only because of its higher efficiency as compared to conventional coal firing plants, but also due to a higher driving force in the form of high partial pressure. One of the novel technological concepts currently being developed and investigated is membranes for carbon dioxide (CO2) separation, due to simplicity and ease of scaling. A challenge in using membranes for CO2 capture in IGCC is the possibility of failure at elevated temperatures or pressures. Our earlier research studies examined the use of ionic liquids on various supports for CO2 separation over the temperature range, 37°C-300°C. The ionic liquid, 1-hexyl-3methylimidazolium Bis(trifluoromethylsulfonyl)imide, ([hmim][Tf2N]), was chosen for our initial studies with the following supports: polysulfone (PSF), poly(ether sulfone) (PES), and cross-linked nylon. The PSF and PES supports had similar performance at room temperature, but increasing temperature caused the supported membranes to fail. The ionic liquid with the PES support greatly affected the glass transition temperature, while with the PSF, the glass transition temperature was only slightly depressed. The cross-linked nylon support maintained performance without degradation over the temperature range 37-300°C with respect to its permeability and selectivity. However, while the cross-linked nylon support was able to withstand temperatures, the permeability continued to increase and the selectivity decreased with increasing temperature. Our studies indicated that further testing should examine the use of other ionic liquids, including those that form chemical complexes with CO2 based on amine interactions. The hypothesis is that the performance at the elevated temperatures could be improved by allowing a facilitated transport mechanism to become dominant. Several amine-based ionic liquids were tested on the cross-linked nylon support. It was found that using the amine-based ionic liquid did improve selectivity and permeability at higher temperature. The hypothesis was confirmed, and it was determined that the type of amine used also played a role in facilitated transport. Given the appropriate aminated ionic liquid with the cross-linked nylon support, it is possible to have a membrane capable of separating CO2 at IGCC conditions. With this being the case, the research has expanded to include separation of other constituents besides CO2 (CO, H2S, etc.) and if they play a role in membrane poisoning or degradation. This communication will discuss the operation of the recently fabricated ionic liquid membranes and the impact of gaseous components other than CO2 on their performance and stability.

Myers, C.R.; Ilconich, J.B.; Luebke, D.R.; Pennline, H.W.

2008-07-12

172

p-Nitrophenolate: a probe for determining acid strength in ionic liquids.  

PubMed

In order to obtain an acidity scale in room-temperature ionic liquid solutions, the protonation equilibrium of sodium p-nitrophenolate in [bm(2)im][NTf(2)] and in [bmpyrr][NTf(2)], at 298 K, has been studied by means of spectrophotometric titration. Carboxylic acids differing in both structure and in water solution strength have been used. Data collected indicate that in the analyzed ionic liquid solutions carboxylic acids are less dissociated than in water solution. Furthermore, by virtue of a mutual interaction, the studied equilibrium seems to be affected by both the nature of the ionic liquids and the carboxylic acids. PMID:19170605

D'Anna, Francesca; La Marca, Sandra; Noto, Renato

2009-03-01

173

Spectroelectrochemical identification of a pentavalent uranyl tetrachloro complex in room-temperature ionic liquid.  

PubMed

Reduction of U(VI)O(2)Cl(4)(2-) in a mixture of 1-ethyl-3-methylimidazolium tetrafluoroborate and its chloride at E°' = -0.996 V vs Fc/Fc(+) and 298 K affords U(V)O(2)Cl(4)(3-), which is kinetically stable and exhibits typical character of U(V) in the UV-vis-NIR absorption spectrum. PMID:21970374

Ogura, Toshinari; Takao, Koichiro; Sasaki, Kotoe; Arai, Tsuyoshi; Ikeda, Yasuhisa

2011-10-04

174

Room-Temperature Ionic Liquids and Protective Phospholipid Membranes: Interactions on Surfaces  

Technology Transfer Automated Retrieval System (TEKTRAN)

Green chemistry is a growing area of research that involves reducing or eliminating hazardous materials (products and solvents) from chemical processes. An area of green chemistry that is quite interesting to us is bioelectrocatalytic transformation of lipids in non-aqueous solvents called room-tem...

175

Room-temperature ionic liquids: temperature dependence of gas solubility selectivity  

SciTech Connect

This study focuses on bulk fluid solubility of carbon dioxide (CO{sub 2}), methane (CH{sub 4}), hydrogen (H{sub 2}), and nitrogen (N{sub 2}) gases in the imidazolium-based RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((emim)(Tf{sub 2}N)),1-ethyl-3-methylimidazolium tetrafluoroborate ((emim)(BF{sub 4})),1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide((hmim)(Tf{sub 2}N)), and 1,3-dimethylimidazolium methyl sulfate ((mmim)(MeSO{sub 4})) as a function of temperature (25, 40, 55, and 70{sup o}C) at near-atmospheric pressures. The experimental behaviors are explained in terms of thermodynamic relationships that account for the negligible vapor pressure of the RTIL as well as the low solubilities of the gases. Results show that, as temperature increases, the solubility of CO{sub 2} decreases in all RTILs, the solubility of CH{sub 4} remains constant in (emim)(Tf{sub 2}N) and (hmim)(Tf{sub 2}N) but increases in(mmim)(MeSO{sub 4}) and (emim)(BF{sub 4}), and the solubility of N{sub 2} and H{sub 2} increases. Also, the ideal solubility selectivity (ratio of pure-component solubilities) increases as temperature decreases for CO{sub 2}/N{sub 2}, CO{sub 2}/CH{sub 4}, and CO{sub 2}/H{sub 2} systems. Experimental values for the enthalpy and entropy of solvation are reported.

Alexia Finotello; Jason E. Bara; Dean Camper; Richard D. Noble [University of Colorado, Boulder, CO (United States). Department of Chemical and Biological Engineering

2008-05-15

176

Viscosity of a room temperature ionic liquid: predictions from nonequilibrium and equilibrium molecular dynamics simulations.  

PubMed

Nonequilibrium molecular dynamics (NEMD) simulations have been performed on 1-methyl-3-ethyl-imidazolium bis(trifluoromethane)sulfonimide [emim][Ntf(2)] using Lees-Edwards boundary conditions. A range of inverse shear rates corresponding to a fraction of the rotational relaxation time for the slowest relaxing molecular axis of anion and cation to 20 rotational relaxation times (1/20 tau(rot) < gamma < 5/tau(rot)) has been investigated. An extrapolation of the shear-rate-dependent viscosity obtained from these simulations to zero shear rate using the empirical three-parameter Carreau equation yielded excellent agreement with the viscosity obtained from equilibrium MD simulations. Based upon the Carreau equation fit to the simulation data, shear-thinning behavior was observed in [emim][Ntf(2)] for all shear rates investigated, implying that Newtonian behavior is observed in [emim][Ntf(2)] only for shear rates significantly lower than the inverse rotational relaxation time. A close resemblance between the apparent time-dependent viscosity extracted from equilibrium MD simulations and the shear-rate-dependent viscosity extracted from NEMD simulations has been found and discussed. MD simulations accurately predicted [emim][Ntf(2)] density, self-diffusion coefficients, heat of vaporization, and lattice parameters for the crystalline phase. PMID:19275203

Borodin, Oleg; Smith, Grant D; Kim, Hojin

2009-04-01

177

Research in New Ionic Liquids.  

National Technical Information Service (NTIS)

Ionic Liquids are a family of salts which by definition have very low melting points that are at or below the boiling point of water (<100 C).1-4 They typically have very long liquidous ranges before they decompose, with essentially no vapor pressure in t...

G. Drake R. Hawkins

2004-01-01

178

Spontaneous product segregation from reactions in ionic liquids: application in Pd-catalyzed aliphatic alcohol oxidation.  

PubMed

A methodology is introduced to separate polar reaction products from ionic liquids without the need for organic solvent extraction or distillation. We investigated product isolation after an alcohol oxidation performed in ionic liquids. Suitable ionic liquids were selected based on their mixing or demixing with a range of alcohols and the derived ketones. The aim was to obtain complete miscibility with the alcohol substrate at reaction temperature and a clear phase separation of the derived ketone product at room temperature. Six imidazolium based ionic liquids displayed this desired behaviour and were sufficiently stable to oxidation. These ionic liquids were then employed in the oxidation of non-activated aliphatic alcohols with molecular oxygen in the presence of palladium(II) acetate. In 1-butyl-3-methylimidazolium tetrafluoroborate, 2-ketone yields of 79 and 86% were obtained for, respectively, 2-octanol and 2-decanol. After cooling to room temperature the ionic liquid expels the immiscible ketone and the product phase can be isolated by decantation. In addition, the ionic liquid acts as an immobilization medium for the palladium catalyst, allowing efficient catalyst recycling. PMID:20145838

Van Doorslaer, Charlie; Schellekens, Yves; Mertens, Pascal; Binnemans, Koen; De Vos, Dirk

2009-12-21

179

Synthesis and characterization of new pyrrolidinium based protic ionic liquids. Good and superionic liquids.  

PubMed

New pyrrolidinium-cation-based protic acid ionic liquids (PILs) were prepared through a simple and atom-economic neutralization reactions between pyrrolidine and Brønsted acids, HX, where X is NO 3 (-), HSO 4 (-), HCOO (-), CH 3COO (-) or CF 3COO (-) and CH 3(CH 2) 6COO (-). The thermal properties, densities, electrochemical windows, temperature dependency of dynamic viscosity and ionic conductivity were measured for these PILs. All protonated pyrrolidinium salts studied here were liquid at room temperature and possess a high ionic conductivity (up to 56 mS cm (-1)) at room temperature. Pyrrolidinium based PILs have a relatively low cost, a low toxicity and exhibit a large electrochemical window as compared to other protic ionic liquids (up 3 V). Obtained results allow us to classify them according to a classical Walden diagram and to determinate their "Fragility". Pyrrolidinium based PILs are good or superionic liquids and shows extremely fragility. They have wide applicable perspectives for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media as replacements of conventional inorganic acids. PMID:18826270

Anouti, Mérièm; Caillon-Caravanier, Magaly; Dridi, Yosra; Galiano, Herve; Lemordant, Daniel

2008-10-01

180

Electrochemically stable fluorohydrogenate ionic liquids based on quaternary phosphonium cations  

Microsoft Academic Search

Fluorohydrogenate ionic liquids of quaternary phosphonium cations, tri-n-butylmethylphosphonium (P4441) fluorohydrogenate, tetra-n-butylphosphonium (P4444) fluorohydrogenate, and tri-n-butyl-n-octylphosphonium (P4448) fluorohydrogenate, have been synthesized by the metatheses of anhydrous hydrogen fluoride and the corresponding phosphonium chloride precursors. All the obtained salts have melting points below room-temperature with a vacuum-stable composition of P444m(FH)2.3F (m=1, 4, and 8) and were characterized by density, conductivity, and viscosity

Shunsuke Kanematsu; Kazuhiko Matsumoto; Rika Hagiwara

2009-01-01

181

Thermophysical Properties of Ionic Liquids  

NASA Astrophysics Data System (ADS)

Low melting point salts which are often classified as ionic liquids have received significant attention from research groups and industry for a range of novel applications. Many of these require a thorough knowledge of the thermophysical properties of the pure fluids and their mixtures. Despite this need, the necessary experimental data for many properties is scarce and often inconsistent between the various sources. By using accurate data, predictive physical models can be developed which are highly useful and some would consider essential if ionic liquids are to realize their full potential. This is particularly true if one can use them to design new ionic liquids which maximize key desired attributes. Therefore there is a growing interest in the ability to predict the physical properties and behavior of ionic liquids from simple structural information either by using group contribution methods or directly from computer simulations where recent advances in computational techniques are providing insight into physical processes within these fluids. Given the importance of these properties this review will discuss the recent advances in our understanding, prediction and correlation of selected ionic liquid physical properties.

Rooney, David; Jacquemin, Johan; Gardas, Ramesh

182

TEMPO-catalyzed oxidation of benzylic alcohols to aldehydes with the H 2O 2\\/HBr\\/ionic liquid [bmim]PF 6 system  

Microsoft Academic Search

A selective oxidation of benzylic alcohols to the corresponding aldehydes in room temperature ionic liquid was achieved by using TEMPO\\/HBr\\/H2O2 system, and both ether-insoluble acetamido-TEMPO and ionic liquid [bmim]PF6 can be successfully recovered and reused for the oxidation of the same (different) substrate.

Nan Jiang; Arthur J. Ragauskas

2005-01-01

183

Functionalized ionic liquids based on guanidinium cations with two ether groups as new electrolytes for lithium battery  

Microsoft Academic Search

Two new functionalized ionic liquids (ILs) based on guanidinium cation with two ether groups and TFSA? anion are synthesized and characterized. Their physicochemical and electrochemical properties, including melting point, thermal stability, density, viscosity, conductivity, and electrochemical window are determined. Both the ILs are liquids at room temperature, and the viscosities are about 60mPas at 25°C. Behavior of lithium redox, chemical

Yide Jin; Shaohua Fang; Li Yang; Shin-ichi Hirano; Kazuhiro Tachibana

2011-01-01

184

Solubility and aggregation of charged surfactants in ionic liquids.  

PubMed

Room-temperature ionic liquids (ILs) exhibit a unique set of properties, leading to opportunities for numerous applications. To obtain a better understanding of IL interfaces at a molecular level, we combined charged surfactants with ILs and studied their interfacial behavior. The critical micelle concentration (cmc) of each surfactant-IL pair was determined from both solubility phase diagrams and isotherms. Because the cmc is equivalent to the solubility at the Krafft temperature, a connection between the solubility of the surfactant and the physical properties of the underlying ionic liquid was established. Interfacial energy was found to be the major factor affecting the surfactant aggregation process, although its magnitude depends strongly on the IL structure. The results here give insight into explaining the nature of self-assembly of surfactants at IL interfaces and the interaction between solutes and IL solvents. PMID:22168452

Chen, Lang G; Bermudez, Harry

2012-01-05

185

Electrodeposition of magnesium film from BMIMBF4 ionic liquid  

NASA Astrophysics Data System (ADS)

In this paper, we reported for the first time magnesium electrodeposition and dissolution processes in the ionic liquid of BMIMBF4 with 1 M Mg(CF3SO3)2 at room temperature. Our study found that complete electrochemical reoxidation of the electrodeposited magnesium film was feasible only on Ag substrate, comparing with the Pt, Ni, and stainless-steel. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) results showed that magnesium was found in the deposited film and the deposits were dense. The electrodeposition of magnesium on Ag substrate in the ionic liquid was considered to be a reversible process by cyclic voltammetry. Plots of peak current versus the square root of the scan rate were found to be linear, which indicates that the mass-transport process of electroactive species was mainly diffusion controlled. The diffusion coefficient D values of electroactive species were calculated from cyclic voltammetry and chronoamperometry, respectively.

Nuli, Yanna; Yang, Jun; Wang, Pu

2006-09-01

186

Trace detection of oxygen - ionic liquids in gas sensor design.  

PubMed

This paper presents a novel electrochemical membrane sensor on basis of ionic liquids for trace analysis of oxygen in gaseous atmospheres. The faradaic response currents for the reduction of oxygen which were obtained by multiple-potential-step-chronoamperometry could be used for real time detection of oxygen down to concentrations of 30ppm. The theoretical limit of detection was 5ppm. The simple, non-expensive sensors varied in electrolyte composition and demonstrated a high sensitivity, a rapid response time and an excellent reproducibility at room temperature. Some of them were continuously used for at least one week and first results promise good long term stability. Voltammetric, impedance and oxygen detection studies at temperatures up to 200°C (in the presence and absence of humidity and CO2) revealed also the limitations of certain ionic liquids for some electrochemical high temperature applications. Application areas of the developed sensors are control and analysis processes of non oxidative and oxygen free atmospheres. PMID:24148432

Baltes, N; Beyle, F; Freiner, S; Geier, F; Joos, M; Pinkwart, K; Rabenecker, P

2013-07-11

187

Hydrogen substitution effect on the solubility of perhalogenated compounds in ionic liquid [bmim][PF 6  

Microsoft Academic Search

Solubility behaviors of binary mixtures of CFCl3 (R-11), CFCl2-CF2Cl (R-113), CHCl3 (R-20), CDCl3 (R-20-d), CHCl2–CF3 (R-123) with room-temperature ionic liquid [bmim][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate) have been investigated using the volumetric and cloud-point methods, since all the systems show liquid–liquid equilibria (LLE). Large immiscibility (LLE) gaps of the perhalogenated compounds (R-11 and R-113) in the ionic liquid have been drastically reduced by

Mark B. Shiflett; A. Yokozeki

2007-01-01

188

Calculations of Hydrogen-Bonding Interactions between Ions in Room-Temperature Molten Salts.  

National Technical Information Service (NTIS)

Mixtures of 1-methyl-3-ethylimidazolium chloride (MEI)C) and A1CI3 form chloroaluminate salts that are liquid well below room temperature. These melts are of interest as electrolytes, as nonaqueous solvents for studying ionic complexes, and as catalytic s...

C. J. Dymek J. J. Stewart

1989-01-01

189

Ionic Liquids in Analytical Chemistry  

Microsoft Academic Search

The role of ionic liquids (ILs) in analytical chemistry is increasing substantially every year. A decade ago there were but a handful of papers in this area of research that were considered curiosities at best. Today, those publications are recognized as seminal articles that gave rise to one of the most rapidly expanding areas of research in chemical analysis. In

Renee J. Soukup-Hein; Molly M. Warnke; Daniel W. Armstrong

2009-01-01

190

Critical behavior of ionic liquids.  

PubMed

The renormalization of the Landau-Ginzburg Hamiltonian for a system with Coulombic interactions caused by spatially inhomogeneous polarizational effects is discussed. It is shown that for ionic liquids with a strong dependence of the degree of dissociation on density, the nonclassical fluctuation region is significantly narrowed. The essential role of the association of ions is noted. PMID:12188731

Kulinskii, V L; Malomuzh, N P

2002-06-21

191

O-Glycosidation reactions promoted by in situ generated silver N-heterocyclic carbenes in ionic liquids  

Microsoft Academic Search

We herein report O-glycosidation reactions promoted via silver N-heterocyclic carbene complexes formed in situ in ionic liquids. Seven different room temperature ionic liquids were screened for the glycosidation reaction of 4-nitrophenol with tetra-O-acetyl-?-d-galactopyranosyl bromide. Good to excellent yields were obtained using Ag–NHC complexes derived from imidazolium halide salts to promote the glycosidation reaction, whereas yields considered moderate to low were

Ian Jamie Talisman; Vineet Kumar; Jacqueline Razzaghy; Sanjay V. Malhotra

2011-01-01

192

Wirelessly driven electro-active paper actuator made with cellulose–polypyrrole–ionic liquid and dipole rectenna  

Microsoft Academic Search

This paper reports a wirelessly driven electro-active paper actuator that consists of a dipole rectenna array, a power control circuit and two cellulose–polypyrrole–ionic liquid (CPIL) electro-active paper actuators. The CPIL nanocomposite actuator was fabricated by incorporating nanoscaled PPy onto cellulose by an in situ polymerization technique, which was followed by activation in a room temperature ionic liquid. The CPIL actuator

Sang Yeol Yang; Suresha K Mahadeva; Jaehwan Kim

2010-01-01

193

Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids  

SciTech Connect

The major objective of the project is to establish the feasibility of using specific ionic liquids capable of sustaining aluminum electrolysis near room temperature at laboratory and batch recirculation scales. It will explore new technologies for aluminum and other valuable metal extraction and process methods. The new technology will overcome many of the limitations associated with high temperatures processes such as high energy consumption and corrosion attack. Furthermore, ionic liquids are non-toxic and could be recycled after purification, thus minimizing extraction reagent losses and environmental pollutant emissions. Ionic liquids are mixture of inorganic and organic salts which are liquid at room temperature and have wide operational temperature range. During the last several years, they were emerging as novel electrolytes for extracting and refining of aluminum metals and/or alloys, which are otherwise impossible using aqueous media. The superior high temperature characteristics and high solvating capabilities of ionic liquids provide a unique solution to high temperature organic solvent problems associated with device internal pressure build-up, corrosion, and thermal stability. However their applications have not yet been fully implemented due to the insufficient understanding of the electrochemical mechanisms involved in processing of aluminum with ionic liquids. Laboratory aluminum electrodeposition in ionic liquids has been investigated in chloride and bis (trifluoromethylsulfonyl) imide based ionic liquids. The electrowinning process yielded current density in the range of 200-500 A/m2, and current efficiency of about 90%. The results indicated that high purity aluminum (>99.99%) can be obtained as cathodic deposits. Cyclic voltammetry and chronoamperometry studies have shown that initial stages of aluminum electrodeposition in ionic liquid electrolyte at 30°C was found to be quasi-reversible, with the charge transfer coefficient (0.40). Nucleation phenomena involved in aluminum deposition on copper in AlCl3-BMIMCl electrolyte was found to be instantaneous followed by diffusion controlled three-dimensional growth of nuclei. Diffusion coefficient (Do) of the electroactive species Al2Cl7¯ ion was in the range from 6.5 to 3.9×10–7 cm2?s–1 at a temperature of 30°C. Relatively little research efforts have been made toward the fundamental understanding and modeling of the species transport and transformation information involved in ionic liquid mixtures, which eventually could lead to quantification of electrochemical properties. Except that experimental work in this aspect usually is time consuming and expensive, certain characteristics of ionic liquids also made barriers for such analyses. Low vapor pressure and high viscosity make them not suitable for atomic absorption spectroscopic measurement. In addition, aluminum electrodeposition in ionic liquid electrolytes are considered to be governed by multi-component mass, heat and charge transport in laminar and turbulent flows that are often multi-phase due to the gas evolution at the electrodes. The kinetics of the electrochemical reactions is in general complex. Furthermore, the mass transfer boundary layer is about one order of magnitude smaller than the thermal and hydrodynamic boundary layer (Re=10,000). Other phenomena that frequently occur are side reactions and temperature or concentration driven natural convection. As a result of this complexity, quantitative knowledge of the local parameters (current densities, ion concentrations, electrical potential, temperature, etc.) is very difficult to obtain. This situation is a serious obstacle for improving the quality of products, efficiency of manufacturing and energy consumption. The gap between laboratory/batch scale processing with global process control and nanoscale deposit surface and materials specifications needs to be bridged. A breakthrough can only be realized if on each scale the occurring phenomena are understood and quantified. Multiscale numerical modeling nevertheless can help t

Dr. R. G. Reddy

2007-09-01

194

Coherence time of the nuclear spin of ionized phosphorus donors in ^28Si at liquid He and room temperature  

NASA Astrophysics Data System (ADS)

Remarkable coherence times have recently been reported for the nuclear spin of dilute neutral ^31P in highly enriched ^28Si [1]. For ionized ^31P, the removal of the hyperfine-coupled electron should result in a nuclear spin even more decoupled from the environment, and hence even longer coherence times at cryogenic temperatures. The coherence time of ionized ^31P was recently observed in natural Si, and while the nuclear coherence time was indeed much longer than the electron coherence time measured in the same device, it was limited to 18 ms due to both the presence of ^29Si as well as the readout mechanism being employed [2]. Here we report on coherence time measurements for ionized ^31P in the same ^28Si samples used for the previous [1] neutral donor study. In addition to the promise of longer cryogenic coherence times, the removal of the hyperfine-coupled electron should result in a profound change in the temperature dependence of T2. For the neutral donor, the electron T1 decreases very rapidly with increasing temperature, and even at 4.2 K the nuclear T2 is limited by the electron T1 [1]. This mechanism is absent for the ionized donor, and we will report on nuclear coherence time measurements for ionized ^31P at room temperature.[4pt] [1] M. Steger et al., Science 336, 1280 (2012).[0pt] [2] L. Dreher et al., Phys. Rev. Lett. 108, 027602 (2012).

Thewalt, Michael L. W.; Saeedi, Kamyar; Simmons, Stephanie; Morton, John J. L.

2013-03-01

195

Ionic liquid ion sources: characterization of externally wetted emitters.  

PubMed

The feasibility of electrostatically extracting and accelerating ions from room temperature ionic liquids in a high vacuum environment is investigated using externally wetted emitters similar to those manufactured for liquid metal ion sources, made out of tungsten wire and electrochemically treated to produce a sharp tip and to increase surface wettability. The ionic liquid EMI-BF4 is used as a prototypical example. The temperature dependence on emission current suggests that liquid flow over the metallic surface is limited by viscosity. Time-of-flight spectrometry indicates that the beam is composed of EMI+ and (EMI-BF4)EMI+ ions in the positive polarity and BF4- and (EMI-BF4)BF4- ions in the negative polarity, and that these ions are emitted with energies very close to their applied potentials. Angular distribution measurements in positive and negative polarities show that ions travel near the propagation axis, diverging by not more than 18 degrees from the centerline. Thanks to the extraordinary variety of ionic liquids it should be possible to generate a correspondingly large number of bipolar nonmetallic ion beams each with unique properties and applicability in fields as diverse as ion lithography, analytical equipment and space propulsion. PMID:15589547

Lozano, Paulo; Martínez-Sánchez, Manuel

2005-02-15

196

Surface tension of ionic liquids and ionic liquid solutions.  

PubMed

Some of the most active scientific research fronts of the past decade are centered on ionic liquids. These fluids present characteristic surface behavior and distinctive trends of their surface tension versus temperature. One way to explore and understand their unique nature is to study their surface properties. This critical review analyses most of the surface tension data reported between 2001 and 2010 (187 references). PMID:21811714

Tariq, Mohammad; Freire, Mara G; Saramago, Benilde; Coutinho, João A P; Lopes, José N Canongia; Rebelo, Luís Paulo N

2011-08-02

197

Copper(II)-catalyzed aerobic oxidation of primary alcohols to aldehydes in ionic liquid [bmpy]PF6.  

PubMed

A room-temperature aerobic oxidation of primary alcohols to aldehydes catalyzed by the three-component system acetamido-TEMPO/Cu(ClO(4))(2)/DMAP in the ionic liquid [bmpy]PF(6) has been developed, and the catalysts can be recycled and reused for five runs without any significant loss of catalytic activity. [reaction: see text] PMID:16092851

Jiang, Nan; Ragauskas, Arthur J

2005-08-18

198

Solvation structure of iron group metal ion in TFSA-based ionic liquids investigated by Raman spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

Solvation structures of the iron group metal ion in ionic liquids were researched.Raman spectrum shows the concentration dependence.Solvation numbers have been investigated at room temperature and at 150 °C.The geometries and SCF energies were examined using the theoretical DFT calculations.

Matsumiya, Masahiko; Kamo, Yoichi; Hata, Katsunori; Tsunashima, Katsuhiko

2013-09-01

199

Ionic liquids in biomass processing.  

PubMed

Ionic liquids have been studied for their special solvent properties in a wide range of processes, including reactions involving carbohydrates such as cellulose and glucose. Biomass is a widely available and renewable resource that is likely to become an economically viable source of starting materials for chemical and fuel production, especially with the price of petroleum set to increase as supplies are diminished. Biopolymers such as cellulose, hemicellulose and lignin may be converted to useful products, either by direct functionalisation of the polymers or depolymerisation to monomers, followed by microbial or chemical conversion to useful chemicals. Major barriers to the effective conversion of biomass currently include the high crystallinity of cellulose, high reactivity of carbohydrates and lignin, insolubility of cellulose in conventional solvents, as well as heterogeneity in the native lignocellulosic materials and in lignin itself. This combination of factors often results in highly heterogeneous depolymerisation products, which make efficient separation difficult. Thus the extraction, depolymerisation and conversion of biopolymers will require novel reaction systems in order to be both economically attractive and environmentally benign. The solubility of biopolymers in ionic liquids is a major advantage of their use, allowing homogeneous reaction conditions, and this has stimulated a growing research effort in this field. This review examines current research involving the use of ionic liquids in biomass reactions, with perspectives on how it relates to green chemistry, economic viability, and conventional biomass processes. PMID:21107802

Tan, Suzie Su Yin; Macfarlane, Douglas R

2010-01-01

200

Ionic Liquids in Biomass Processing  

NASA Astrophysics Data System (ADS)

Ionic liquids have been studied for their special solvent properties in a wide range of processes, including reactions involving carbohydrates such as cellulose and glucose. Biomass is a widely available and renewable resource that is likely to become an economically viable source of starting materials for chemical and fuel production, especially with the price of petroleum set to increase as supplies are diminished. Biopolymers such as cellulose, hemicellulose and lignin may be converted to useful products, either by direct functionalisation of the polymers or depolymerisation to monomers, followed by microbial or chemical conversion to useful chemicals. Major barriers to the effective conversion of biomass currently include the high crystallinity of cellulose, high reactivity of carbohydrates and lignin, insolubility of cellulose in conventional solvents, as well as heterogeneity in the native lignocellulosic materials and in lignin itself. This combination of factors often results in highly heterogeneous depolymerisation products, which make efficient separation difficult. Thus the extraction, depolymerisation and conversion of biopolymers will require novel reaction systems in order to be both economically attractive and environmentally benign. The solubility of biopolymers in ionic liquids is a major advantage of their use, allowing homogeneous reaction conditions, and this has stimulated a growing research effort in this field. This review examines current research involving the use of ionic liquids in biomass reactions, with perspectives on how it relates to green chemistry, economic viability, and conventional biomass processes.

Tan, Suzie Su Yin; Macfarlane, Douglas R.

201

Diffusion Coefficient of Tin(II) Methanesulfonate in Ionic Liquid and Methane Sulfonic Acid (MSA) Solvent  

NASA Astrophysics Data System (ADS)

Voltammetry and chronoamperometry for the electrodeposition of tin from Tin(II) methane sulfonate mixed with ionic liquid and methane sulfonate acid at room temperature was studied. Cyclic voltammetry shows redox waves of Tin(II), which proves that the electrodeposition of tin from Tin(II) methane sulfonate is a diffusion-controlled process. The diffusion coefficient of Tin(II) ions in the solvent mixture showed good agreement from both voltammetry and chronoamperometry results. The diffusion coefficient of Tin(II) in the mixture was much smaller than in aqueous solution, and it depends on the anion of the ionic liquid.

Yang, Kok Kee; Mahmoudian, M. R.; Ebadi, Mehdi; Koay, Hun Lee; Basirun, Wan Jeffrey

2011-12-01

202

Vertical alignment of liquid crystal through ion beam exposure on oxygen-doped SiC films deposited at room temperature  

SciTech Connect

The authors report the vertical alignment of liquid crystal (LC) through the ion beam exposure on amorphous oxygen-doped SiC (SiOC) film surfaces deposited at room temperature. The optical transmittance of these films was similar to that of polyimide layers, but much higher than that of SiO{sub x} films. The light leakage of a LC cell aligned vertically on SiOC films was much lower than those of a LC cell aligned on polyimide layers or other inorganic films. They found that LC molecules align vertically on ion beam treated SiOC film when the roughness of the electrostatic force microscopy (EFM) data is high on the SiOC film surface, while they align homogeneously when the roughness of the EFM data is low.

Son, Phil Kook; Park, Jeung Hun; Kim, Jae Chang; Yoon, Tae-Hoon; Rho, Soon Joon; Jeon, Back Kyun; Shin, Sung Tae; Kim, Jang Sub; Lim, Soon Kwon [School of Electrical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); LC/OLED Research Team, LCD R and D Center, LCD Business, Samsung Electronics Co. Ltd., Yongin, Gyeonggi-Do 449-711 (Korea, Republic of); Process Development Team, LCD R and D Center, LCD Business, Samsung Electronics Co. Ltd., Yongin, Gyeonggi-Do 449-711 (Korea, Republic of)

2007-09-03

203

Immobilization of Cyphos Ionic Liquids in Alginate Capsules for Cd(II) Sorption  

Microsoft Academic Search

Four phosphonium ionic liquids (Cyphos IL-101, IL-105, IL-109, and IL-111) have been immobilized in composite biopolymer capsules (alginate\\/gelatin). The resins were tested for Cd(II) sorption in HCl solutions. Cyphos IL-111 being solid at room temperature, the phase change contributes to the formation of large vesicles in the resin particle. Sorption isotherms were not affected by the anionic counterpart (chloride, dicyanamide,

E. Guibal; A. Figuerola Piñol; M. Ruiz; T. Vincent; C. Jouannin; A. M. Sastre

2010-01-01

204

Molybdenum electrodes for hydrogen production by water electrolysis using ionic liquid electrolytes  

Microsoft Academic Search

The hydrogen production by water electrolysis was tested with different electrocatalysts (molybdenum, nickel, iron alloys containing chromium, manganese and nickel) using aqueous solutions of ionic liquid (IL) like 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4). The hydrogen evolution reaction (HER) was performed at room temperature in a potential of ?1.7V (PtQRE). A Hoffman cell apparatus was used to water electrolysis with current density values,

Roberto F. de Souza; Gabriel Loget; Janine C. Padilha; Emilse M. A. Martini; Michele O. de Souza

2008-01-01

205

Behaviour of Ionic Effects on Response Times of Surface Stabilized Ferroelectric Liquid Crystal Devices  

NASA Astrophysics Data System (ADS)

The response time measurements of a new room temperature ferroelectric liquid crystal have been done by using the field reversal method. The response time has been found to be frequency dependent and decreases considerably at frequencies above 10 kHz. The temperature dependence of response time showed the presence of ionic effects as is evident from the appearance of the second peak in the current response to an applied bipolar pulse.

Saxena, Kanchan; Bawa, S. S.; Biradar, A. M.; Chandra, Subhas; Rup, Raj

1990-10-01

206

Recent developments in the use of non-aqueous ionic liquids for two-phase catalysis  

Microsoft Academic Search

One of the most important recent developments in homogeneous catalysis is the introduction of the aqueous two-phase technique. This method uses a homogeneous catalyst dissolved in water. The catalyst separation from the products can be easily achieved by simple phase decantation. Room-temperature ionic liquids based on organic cations, such as dialkylimidazolium, and inorganic anions, such as AlCl4?, Al2Cl7?, BF4?, PF6?

Hélène Olivier

1999-01-01

207

In situ Raman study of dissolved carbon-dioxide induced changes of imidazolium-based ionic liquids  

NASA Astrophysics Data System (ADS)

In situ Raman spectroscopic analysis has been performed for room temperature ionic liquid (RTIL) + CO2 systems under two-phase equilibrium conditions at room temperature. The Raman spectra indicate the followings: the vibration state and configuration of 1-ethyl-3-methylimidazolium tetrafluoroborate change by CO2 dissolution; the liquid structure of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide barely changes by addition of CO2 pressure up to 30 MPa. In addition, the information of the RTIL structure suggests that the large change of the vibration state and configuration of the RTIL does not necessarily relate to the high CO2 solubility in the RTIL.

Makino, Takashi

2010-03-01

208

Room temperature inorganic ``quasi-molten salts`` as alkali-metal electrolytes  

Microsoft Academic Search

Room temperature inorganic liquids of high ionic conductivity have been prepared by reacting Lewis acid AlCl with sulfonyl chlorides. The mechanism is not clear at this time since a crystal structure study of the 1:1 complex with CHâSOâCl (T{sub m} = 30 C) is not consistent with a simple chloride transfer to create AlClOâ⁻ anions. The liquid is in a

K. Xu; S. Zhang; C. A. Angell

1996-01-01

209

Early Events in Ionic Liquid Radiation Chemistry  

SciTech Connect

Ionic liquids are interesting and useful materials whose solvation time scales are up to thousands of times longer than in conventional solvents. The extended lifetimes of pre-solvated electrons and other energetic species in ionic liquids has profound consequences for the radiolytic product distributions and reactivity patterns. We use a newly developed, multiplexed variation of pulse-probe spectroscopy to measure the kinetics of the early dynamical and reactive events in ionic liquids.

Wishart, J.F.; Cook, A.; Rimmer, R.D.; Gohdo, M.

2010-09-14

210

Enzyme catalysis with small ionic liquid quantities  

Microsoft Academic Search

Enzyme catalysis with minimal ionic liquid quantities improves reaction rates, stereoselectivity and enables solvent-free\\u000a processing. In particular the widely used lipases combine well with many ionic liquids. Demonstrated applications are racemate\\u000a separation, esterification and glycerolysis. Minimal solvent processing is also an alternative to sluggish solvent-free catalysis.\\u000a The method allows simplified down-stream processing, as only traces of ionic liquids have to

Fabian Fischer; Julien Mutschler; Daniel Zufferey

2011-01-01

211

A binary ionic liquid system composed of N-methoxyethyl- N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide and lithium bis(trifluoromethanesulfonyl)imide: A new promising electrolyte for lithium batteries  

Microsoft Academic Search

Room temperature ionic liquids are nowadays the most appealing research target in the field of liquid electrolytes for lithium batteries, due to their high thermal stability, ionic conductivity and wide electrochemical windows. The cation structure of such solvents strictly influences their physical and chemical properties, in particular the viscosity and conductivity.In this paper we report on the preparation and characterization

S. Ferrari; E. Quartarone; P. Mustarelli; A. Magistris; S. Protti; S. Lazzaroni; M. Fagnoni; A. Albini

2009-01-01

212

Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source  

SciTech Connect

We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au{sup 60+}. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

Thorn, A.; Ritter, E.; Zschornack, G. [Fachrichtung Physik, Technische Universitaet Dresden, Helmholtzstrasse 10, D-01069 Dresden (Germany); Ullmann, F. [DREEBIT GmbH, Zur Wetterwarte 50, D-01109 Dresden (Germany); Pilz, W.; Bischoff, L. [Helmholtzzentrum Dresden-Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany)

2012-02-15

213

Ionic liquids screening for desulfurization of natural gasoline by liquid-liquid extraction.  

PubMed

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization of NG was performed by means of liquid-liquid extraction method at room temperature and atmospheric pressure. Experimental ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the cation on the desulphurization process. ILs based on halogen-ferrates and halogen-aluminates exhibited the highest efficiency in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least 1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method to recover and reuse water-sensitive to halogenated precursors is described. PMID:20091120

Likhanova, Natalya V; Guzmán-Lucero, Diego; Flores, Eugenio A; García, Paloma; Domínguez-Aguilar, Marco A; Palomeque, Jorge; Martínez-Palou, Rafael

2010-01-21

214

Novel polymer electrolytes based on gelatin and ionic liquids  

NASA Astrophysics Data System (ADS)

This study describes the results of the characterization of polymer electrolytes using gelatin matrix doped with europium triflate and/or different ionic liquids.Samples of solvent-free electrolytes were prepared and characterized by ionic conductivity measurements, thermal analysis, electrochemical stability, X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy.Electrolyte samples are thermally stable up to approximately 220 °C. All the materials synthesized are totally amorphous. The room temperature conductivity maximum of this electrolyte system is based on ionic liquid 1-ethyl-3-methylimidazolium acetate, (C2mim)(OAc) (1.18 × 10-4 S cm-1 at 30 °C). The electrochemical stability domain of all samples is about 2.0 V versus Li/Li+. This new series of materials represents a promising alternative in polymer electrolytes research field. The preliminary studies carried out with electrochromic devices (ECDs) incorporating optimized compositions have confirmed that these materials may perform as satisfactory multifunctional component layers in the field of "smart windows". This new materials, will open a land of promising applications in many areas: optics, energy, medicine for example as membranes and separation devices, ECD-based devices, sensors, etc.

Leones, Rita; Sentanin, F.; Rodrigues, Luísa C.; Ferreira, Rute A. S.; Marrucho, Isabel M.; Esperança, José M. S. S.; Pawlicka, Agnieszka; Carlos, Luís D.; Manuela Silva, M.

2012-12-01

215

Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications  

SciTech Connect

Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

Liao, Chen [ORNL; Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL

2013-01-01

216

DNA strands robed with ionic liquid moiety.  

PubMed

An ionic liquid domain was successfully prepared outside double-stranded DNA by fixing 1-alkyl-3-methyl-imidazolium (C(n)MI) cations on the phosphate groups of DNA. First, four species of ionic liquid were made using phosphoric acid di-n-butyl ester and C(n)MI (n=2,4,8, and 12) as a low molecular weight model. They were obtained as liquid salts, and their ionic conductivity ranged up to 10(-5)Scm(-1) at 50 degrees C. Based on this model study, counter cations of the phosphate groups of DNA were exchanged for four kinds of imidazolium cations. The resulting ionic liquid-robed DNA (IL-robed DNA) was soluble in ordinary organic solvents such as methanol or ethanol. Ionic conductivity was low, because the ion density was insufficient to form a continuous ionic liquid domain around the DNA strands. When 11mol% 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF(4)), which is a typical ionic liquid, was mixed with the IL-robed DNA, an ionic conductivity of 5.4 x 10(-5) S cm(-1) at 30 degrees C was observed because a continuous ionic liquid domain was successfully formed. PMID:15860212

Nishimura, Naomi; Nomura, Yasuhiro; Nakamura, Nobuhumi; Ohno, Hiroyuki

2005-09-01

217

Pentadecyl phenol- and cardanol-functionalized fluorescent, room-temperature liquid-crystalline perylene bisimides: effect of pendant chain unsaturation on self-assembly.  

PubMed

A new perylene bisimide (PBI) building block based on pentadecyl phenol (PDP) or cardanol was developed, which upon esterification with 3,4,5-tridodecyloxy gallate resulted in highly emissive, room-temperature liquid-crystalline (LC) molecules. The self assembly in solution was studied in detail by NMR spectroscopy, UV/Vis absorption, and fluorescence spectroscopy. In solution both PDP- and cardanol-based PBI exhibited similar behavior. They were molecularly dissolved in chloroform (CHCl(3)) but formed rotationally displaced H-type aggregates that emitted at 640 nm in methylcyclohexane (MCH). Surface morphology in dropcast films were characterized using microscopic techniques such as SEM, TEM, and atomic force microscopy (AFM). The liquid-crystalline properties were studied using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and variable-temperature X-ray (small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WXRD)) studies. Variable-temperature X-ray studies in the LC phase indicated strong ?-? stacking interaction present in the PDP-based PBI derivative, whereas the stacking was absent in the LC phase of the cardanol-based PBI. The latter formed self-organized structures of extremely short length due to the presence of cis double bonds in the C15 alkyl side chain, whereas the saturated alkyl side chain in PDP could pack efficiently, thereby resulting in nanofibers that were several micrometers in length. PMID:21956257

Bhavsar, Ghanashyam A; Asha, S K

2011-09-28

218

Tetraalkylphosphonium Polyoxometalates as Novel Ionic Liquids.  

National Technical Information Service (NTIS)

The pairing of a Lindqvist or Keggin polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation, has been shown to yield an original family of ionic liquids (POM-ILs), among them salts liquid at or near ambient temperature. The physicoch...

J. F. Wishart M. A. Firestone M. L. Dietz M. R. Antonio P. G. Rickert

2007-01-01

219

Quantized friction across ionic liquid thin films.  

PubMed

Ionic liquids - salts in the liquid state under ambient conditions - are of great interest as precision lubricants. Ionic liquids form layered structures at surfaces, yet it is not clear how this nano-structure relates to their lubrication properties. We measured the friction force between atomically smooth solid surfaces across ionic liquid films of controlled thickness in terms of the number of ion layers. Multiple friction-load regimes emerge, each corresponding to a different number of ion layers in the film. In contrast to molecular liquids, the friction coefficients differ for each layer due to their varying composition. PMID:23942943

Smith, Alexander M; Lovelock, Kevin R J; Gosvami, Nitya Nand; Welton, Tom; Perkin, Susan

2013-08-28

220

Influence of an ionic liquid on the conduction characteristics of lithium niobophosphate glass  

NASA Astrophysics Data System (ADS)

A new solid electrolyte, mol% 1 [EMI]BF4-99(0.5Li2O-0.45P2O5-0.05Nb2O5), with room temperature ionic conductivity of 1.7 × 10-5 S/cm is reported for solid state device applications. Glass transition temperature of the hybrid system decreases by 20 K as compared to the pristine glass. Raman spectra in conjunction with thermal studies reveal that the addition of ionic liquid to the glass seems to increase the disorder in the glass leading to enhanced conductivity.

Dabas, Prashant; Hariharan, K.

2013-02-01

221

Nonlinear polarization of ionic liquids: theory, simulations, experiments  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (RTILs) composed of large, often asymmetric, organic cations and simple or complex inorganic or organic anions do not freeze at ambient temperatures. Their rediscovery some 15 years ago is widely accepted as a ``green revolution'' in chemistry, offering an unlimited number of ``designer'' solvents for chemical and photochemical reactions, homogeneous catalysis, lubrication, and solvent-free electrolytes for energy generation and storage. As electrolytes they are non-volatile, some can sustain without decomposition up to 6 times higher voltages than aqueous electrolytes, and many are environmentally friendly. The studies of RTILs and their applications have reached a critical stage. So many of them can be synthesized - about a thousand are known already - their mixtures can further provide ``unlimited'' number of combinations! Thus, establishing some general laws that could direct the best choice of a RTIL for a given application became crucial; guidance is expected from theory and modelling. But for a physical theory, RTILs comprise a peculiar and complex class of media, the description of which lies at the frontier line of condensed matter theoretical physics: dense room temperature ionic plasmas with ``super-strong'' Coulomb correlations, which behave like glasses at short time-scale, but like viscous liquids at long-time scale. This talk will introduce RTILs to physicists and overview the current understanding of the nonlinear response of RTILs to electric field. It will focus on the theory, simulations, and experimental characterisation of the structure and nonlinear capacitance of the electrical double layer at a charged electrode. It will also discuss pros and contras of supercapacitor applications of RTILs.

Kornyshev, Alexei

2010-03-01

222

Synthesis of benzylidenated hexopyranosides in ionic liquids  

Microsoft Academic Search

The synthesis of 4,6-O-benzylidenated monosaccharides and disaccharides has been studied using ionic liquids as a unique solvent alternative. An examination of several imidazolium ionic liquids indicates that the benzylidenation of hexopyranosides in 3-butyl-1-methylimidazolium tetrafluoroborate, [bmim]BF4, gives the highest yields for most of the substrates, and that this solvent system could be readily recycled.

Jianguo Zhang; Arthur J. Ragauskas

2005-01-01

223

Tuning ionic liquids for hydrate inhibition.  

PubMed

Pyrrolidinium cation-based ionic liquids were synthesized, and their inhibition effects on methane hydrate formation were investigated. It was found that the ionic liquids shifted the hydrate equilibrium line to a lower temperature at a specific pressure, while simultaneously delaying gas hydrate formation. PMID:21547283

Kim, Ki-Sub; Kang, Jeong Won; Kang, Seong-Pil

2011-05-06

224

Ionic Liquids in Chromatography and Capillary Electrophoresis  

Microsoft Academic Search

One of the major challenges facing the chemical industry is the development of new, “green” technologies which reduce the environmental impact of manufacturing processes. Ionic liquids are emerging as a promising alternative to traditional organic solvents and are, thus, generating considerable interest in a variety of areas. This review examines some of the unique properties of ionic liquids and their

A. M. Stalcup; B. Cabovska

2005-01-01

225

Ionic liquid incorporating thiosalicylate for metal removal  

NASA Astrophysics Data System (ADS)

Ionic liquids are a class of organic molten salts "designer solvents" that are composed totally of anions (inorganic and organic polyatomic) and organic cations. The replacement of volatile organic solvents from a separation process is of utmost importance since the use of a large excess of these solvents is hazardous and creates ecological problem. The new method for metal ion extraction is by using task-specific ionic liquids such as ionic liquids which incorporate thiosalicylate functionality. This paper looks at producing a new cluster of ionic liquids which incorporates thiosalicylate with pyridinium cation. Its thermophysical properties such as density and viscosity in single and binary mixtures are studied. The ionic liquids' capability in metal removal processes is evaluated.

Wilfred, Cecilia Devi; Mustafa, Fadwa Babiker; Romeli, Fatimah Julia

2012-09-01

226

Supported Ionic Liquid Membranes for Gas Separation  

SciTech Connect

Ionic liquids have been rapidly gaining attention for various applications including solvent separation and gas capture. These substances are noted for extremely low vapor pressure and high CO2 solubility making them ideal as transport or capture media for CO2 abatement in power generation applications. Ionic liquids, combined with various supports to form membranes, have been proven selective in CO2 separation. Several ionic liquids and a variety of polymer supports have been studied over a temperature range from 37°C to 300°C and have been optimized for stability. The membranes have demonstrated high permeability and high selectivity since the supported ionic liquid membranes incorporate functionality capable of chemically complexing CO2. A study aimed at improving supported ionic liquid membranes will examine their durability with greater transmembrane pressures and the effects on CO2 permeance, CO2/H2 selectivity and thermal stability.

Myers, C.R.; Ilconich, J.B.; Pennline, H.W.; Luebke, D.R.

2007-08-01

227

Depolarization of water in protic ionic liquids.  

PubMed

A mixture of the protic ionic liquid mono-methylammonium nitrate with 1.6 wt% water was investigated from Car-Parrinello molecular dynamics simulations. In contrast to imidazolium-based ionic liquids, the cation possesses strong directional hydrogen bonds to water and all hydrogen bonds in the mixture have a comparable strength. This results in a good incorporation of water into the hydrogen bond network of mono-methylammonium nitrate and a tetrahedral hydrogen bond coordination of water. Hence, one might expect a larger dipole moment of water in the investigated mixture compared to neat water due to the good hydrogen bond network incorporation and the charged vicinity of water in the protic ionic liquid. However, the opposite is observed pointing to strong electrostatic screening in protic ionic liquids. Additionally, the influence of water on the properties of the protic ionic liquid is discussed. PMID:21769354

Zahn, Stefan; Wendler, Katharina; Delle Site, Luigi; Kirchner, Barbara

2011-07-18

228

Electrochemical transistors with ionic liquids for enzymatic sensing  

NASA Astrophysics Data System (ADS)

Over the past decade conducting polymer electrodes have played an important role in bio-sensing and actuation. Recent developments in the field of organic electronics have made available a variety of devices that bring unique capabilities at the interface with biology. One example is organic electrochemical transistors (OECTs) that are being developed for a variety of bio-sensing applications, including the detection of ions, and metabolites, such as glucose and lactate. Room temperature ionic liquids (RTILs) are organic salts, which are liquid at ambient temperature. Their nonvolatile character and thermal stability makes them an attractive alternative to conventional organic solvents. Here we report an enzymatic sensor based on an organic electro-chemical transistor with RTIL's as an integral part of its structure and as an immobilization medium for the enzyme and the mediator. Further investigation shows that these platforms can be incorporated into flexible materials such as carbon cloth and can be utilized for bio-sensing. The aim is to incorporate the overall platform in a wearable sensor to improve athlete performance with regards to training. In this manuscript an introduction to ionic liquids (ILs), IL - enzyme mixtures and a combination of these novel materials being used on OECTs are presented.

Fraser, Kevin J.; Yang, Sang Yoon; Cicoira, Fabio; Curto, Vincenzo F.; Byrne, Robert; Benito-Lopez, Fernando; Khodagholy, Dion; Owens, Róisín M.; Malliaras, George G.; Diamond, Dermot

2011-09-01

229

On the mechanism of radiation-induced polymerization of vinyl monomers in ionic liquid  

NASA Astrophysics Data System (ADS)

An attempt was made to investigate the mechanism controlling the radiation-induced polymerization of vinyl monomers in room temperature ionic liquids. For that purpose, copolymerization of styrene (St) and methyl methacrylate (MMA) was initiated by 60Co gamma radiation in a moisture-stable ionic liquid, [choline chloride][ZnCl2], and its mixture with THF (4:1 v/v). By analyzing the product composition with FTIR for a series of poly(St-co-MMA) samples, it was found that the mole fraction of St in the copolymer is linearly proportional to the mole fraction of St in the feed. Therefore, radiation polymerization in ionic liquid and its mixture with organic solvent is suggested to be a radical propagating process.

Liu, Yaodong; Wu, Guozhong

2005-06-01

230

Theoretical reconstruction and elementwise analysis of photoelectron spectra for imidazolium-based ionic liquids.  

PubMed

We have recently measured core level and valence band XPS, UPS, and MIES spectra of two room temperature ionic liquids composed of bis(trifluoromethylsulfonyl)imide anions ([Tf(2)N](-)) and either 1-ethyl-3-methyl-imidazolium ([EMIm](+)) or 1-octyl-3-methyl-imidazolium cations ([OMIm](+)). [T. Ikari, A. Keppler, M. Reinmöller, W. J. D. Beenken, S. Krischok, M. Marschewski, W. Maus-Friedrichs, O. Höfft and F. Endres, e-J. Surf. Sci. Nanotechnol., 2010, 8, 241.] In the present work we analyze these spectra by means of partial density of states (pDOS) as calculated from a single ion pair of the respective ionic liquid using density functional theory (DFT). Subsequently we reconstruct the XPS and UPS spectra by considering photoemission cross sections and analyze the MIES spectra by pDOS, which provides us decisive hints to the ionic liquid surface structure. PMID:21971301

Reinmöller, Markus; Ulbrich, Angela; Ikari, Tomonori; Preiss, Julia; Höfft, Oliver; Endres, Frank; Krischok, Stefan; Beenken, Wichard J D

2011-10-04

231

Physicochemical studies of PVdF-HFP-based polymer-ionic liquid composite electrolytes  

NASA Astrophysics Data System (ADS)

Polymer-ionic liquid composite electrolytes based on poly (vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) and room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium hexafluorophosphate (DMOImPF6) have been synthesized and studied. The addition of dimethylacetamide (DMA) and propylene carbonate (PC), both with high dielectric constant and low viscosity, to polymer electrolytes has been found to result in an enhancement of conductivity by one order of magnitude. Composite polymer electrolytes containing ionic liquid have been found to be thermally stable upto 300°C. Motional narrowing observed in the variation of line width of 1H and 19F NMR peaks with temperature suggests that both cations and anions are mobile in these electrolytes.

Lalia, Boor Singh; Yamada, K.; Hundal, M. S.; Park, Jin-Soo; Park, Gu-Gon; Lee, Won-Yong; Kim, Chang-Soo; Sekhon, S. S.

2009-08-01

232

Novel hydrophobic ionic liquids electrolyte based on cyclic sulfonium used in dye-sensitized solar cells  

SciTech Connect

A novel series of hydrophobic room temperature ionic liquids based on six cyclic sulfonium cations were first time synthesized and applied in dye-sensitized solar cells as pure solvents for electrolyte system. The chronoamperograms result showed that the length of substituent on sulfonium cations could inhibit the I{sub 3}{sup -} diffusion and the five-ring structure of sulfonium was benefit for fast triiodide ion diffusion. The electrochemical impendence spectra measurement of dye-sensitized solar cells with these ionic liquid electrolytes was carried out and the result indicated that the cations' structure had indeed influence on the cells' performance especially for the fill factor, which was further proved by the measurement result of I-V curves of these dye-sensitized solar cells. The conclusion was obtained that the electron exchange reaction on Pt counter electrode/electrolyte interface dominated the cells' performance for these ionic liquid electrolyte-based DSCs. (author)

Guo, Lei; Pan, Xu; Wang, Meng; Zhang, Changneng; Fang, Xiaqin; Chen, Shuanghong; Dai, Songyuan [Key Lab of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui 230031 (China)

2011-01-15

233

Discontinuities of Ionic Mobilities in Simple Liquids  

Microsoft Academic Search

This Letter reports the results of ionic-mobility measurements in the four simple liquids He I, N2, Ar, and CCl4. Periodic steps in the mobility, like those found earlier in liquid helium II, were found also in these four liquids. We found also a simple relation connecting the critical velocities to the temperatures of the investigated liquids.

L. Bruschi; G. Mazzi; M. Santini

1970-01-01

234

[BPy]HSO4 Acidic Ionic Liquid as a Novel, Efficient, and Environmentally Benign Catalyst for Synthesis of 1,5?Benzodiazepines under Mild Conditions  

Microsoft Academic Search

A novel and simple ionic liquid methodology for the synthesis of 1,5?benzodiazepines is described. 1?Butylpyridinium hydrogen sulphate ([BPy]HSO4), an acidic room?temperature ionic liquid, as a novel and efficient catalyst, was synthesized and used in the preparation of a series of 1,5?benzodiazepine derivatives by the reaction of o?phenylenediamine with chalcones under mild conditions. This method is easy, efficient, environmentally friendly, economical,

Yuying Du; Fuli Tian; Wenzhi Zhao

2006-01-01

235

Ionic liquids for rechargeable lithium batteries  

SciTech Connect

We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium-ion batteries. Thermal stabilities and phase behavior were studied by thermal gravimetric analysis and differential scanning calorimetry. The ionic liquids studied include various imidazoliumTFSI systems, pyrrolidiniumTFSI, BMIMPF{sub 6}, BMIMBF{sub 4}, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF{sub 4}-LiBF{sub 4}, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured for various ionic-liquid lithium-salt systems. We show the development of interfacial impedance in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell and we report results from cycling experiments for a Li|BMIMBF{sub 4} + 1 mol/kg LIBF{sub 4}|C cell. The interfacial resistance increases with time and the ionic liquid reacts with the lithium electrode. As expected, imidazolium-based ionic liquids react with lithium electrodes. We seek new ionic liquids that have better chemical stabilities.

Salminen, Justin; Papaiconomou, Nicolas; Kerr, John; Prausnitz,John; Newman, John

2005-09-29

236

Ionic liquid based dispersive liquid-liquid microextraction for the extraction of pesticides from bananas.  

PubMed

This paper describes a dispersive liquid-liquid microextraction (DLLME) procedure using room temperature ionic liquids (RTILs) coupled to high-performance liquid chromatography with diode array detection capable of quantifying trace amounts of eight pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox and fenazaquin) in bananas. Fruit samples were first homogenized and extracted (1g) with acetonitrile and after suitable evaporation and reconstitution of the extract in 10 mL of water, a DLLME procedure using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) as extraction solvent was used. Experimental conditions affecting the DLLME procedure (sample pH, sodium chloride percentage, ionic liquid amount and volume of disperser solvent) were optimized by means of an experimental design. In order to determine the presence of a matrix effect, calibration curves for standards and fortified banana extracts (matrix matched calibration) were studied. Mean recovery values of the extraction of the pesticides from banana samples were in the range of 69-97% (except for thiophanate-methyl and carbofuran, which were 53-63%) with a relative standard deviation lower than 8.7% in all cases. Limits of detection achieved (0.320-4.66 microg/kg) were below the harmonized maximum residue limits established by the European Union (EU). The proposed method, was also applied to the analysis of this group of pesticides in nine banana samples taken from the local markets of the Canary Islands (Spain). To the best of our knowledge, this is the first application of RTILs as extraction solvents for DLLME of pesticides from samples different than water. PMID:19700165

Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Asensio-Ramos, María; Rodríguez-Delgado, Miguel Angel

2009-08-13

237

Pesticide extraction from table grapes and plums using ionic liquid based dispersive liquid-liquid microextraction.  

PubMed

Room temperature ionic liquids (RTILs) have been used as extraction solvents in dispersive liquid-liquid microextraction (DLLME) for the determination of eight multi-class pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox, and fenazaquin) in table grapes and plums. The developed method involves the combination of DLLME and high-performance liquid chromatography with diode array detection. Samples were first homogenized and extracted with acetonitrile. After evaporation and reconstitution of the extract in water containing sodium chloride, a quick DLLME procedure that used the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) and methanol was developed. The RTIL dissolved in a very small volume of acetonitrile was directed injected in the chromatographic system. The comparison between the calibration curves obtained from standards and from spiked sample extracts (matrix-matched calibration) showed the existence of a strong matrix effect for most of the analyzed pesticides. A recovery study was also developed with five consecutive extractions of the two types of fruits spiked at three concentration levels. Mean recovery values were in the range of 72-100% for table grapes and 66-105% for plum samples (except for thiophanate-methyl and carbofuran, which were 64-75% and 58-66%, respectively). Limits of detection (LODs) were in the range 0.651-5.44 microg/kg for table grapes and 0.902-6.33 microg/kg for plums, representing LODs below the maximum residue limits (MRLs) established by the European Union in these fruits. The potential of the method was demonstrated by analyzing 12 commercial fruit samples (six of each type). PMID:19779926

Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Herrera-Herrera, Antonio V; Rodríguez-Delgado, Miguel Angel

2009-09-25

238

Surface confined ionic liquid as a stationary phase for HPLC  

SciTech Connect

Trimethoxysilane ionosilane derivatives of room temperature ionic liquids based on alkylimidazolium bromides were synthesized for attachment to silica support material. The derivatives 1-methyl-3-(trimethoxysilylpropyl)imidazolium bromide and 1-butyl-3-(trimethoxysilylpropyl)imidazolium bromide were used to modify the surface of 3 {micro}m diameter silica particles to act as the stationary phase for HPLC. The modified particles were characterized by thermogravimetric analysis (TGA) and {sup 13}C and {sup 29}Si NMR spectroscopies. The surface modification procedure rendered particles with a surface coverage of 0.84 {micro}mol m{sup -2} for the alkylimidazolium bromide. The ionic liquid moiety was predominantly attached to the silica surface through two siloxane bonds of the ionosilane derivative (63%). Columns packed with the modified silica material were tested under HPLC conditions. Preliminary evaluation of the stationary phase for HPLC was performed using aromatic carboxylic acids as model compounds. The separation mechanism appears to involve multiple interactions including ion exchange, hydrophobic interaction, and other electrostatic interactions.

Wang, Qian [University of Buffalo, The State University of New York; Baker, Gary A [ORNL; Baker, Sheila N [ORNL; Colon, Luis [Los Alamos National Laboratory (LANL)

2006-01-01

239

Electrorecovery of actinides at room temperature  

SciTech Connect

There are a large number of purification and processing operations involving actinide species that rely on high-temperature molten salts as the solvent medium. One such application is the electrorefining of impure actinide metals to provide high purity material for subsequent applications. There are some drawbacks to the electrodeposition of actinides in molten salts including relatively low yields, lack of accurate potential control, maintaining efficiency in a highly corrosive environment, and failed runs. With these issues in mind we have been investigating the electrodeposition of actinide metals, mainly uranium, from room temperature ionic liquids (RTILs) and relatively high-boiling organic solvents. The RTILs we have focused on are comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and mainly the {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anion [bis(trif1uoromethylsulfonyl)imide {equivalent_to} {sup -}NTf{sub 2}]. These materials represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. In order to ascertain the feasibility of using RTILs for bulk electrodeposition of actinide metals our research team has been exploring the electron transfer behavior of simple coordination complexes of uranium dissolved in the RTIL solutions. More recently we have begun some fundamental electrochemical studies on the behavior of uranium and plutonium complexes in the organic solvents N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO). Our most recent results concerning electrodeposition will be presented in this account. The electrochemical behavior of U(IV) and U(III) species in RTILs and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we have focused on thus far are based on 1,3-dialkylimidazolium or quaternary ammonium cations and {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anions. Our results from XPS studies of e1ectrooxidized uranium metal surfaces indicate that uranium metal reacts with the anion from the RTIL, most likely through an initial f1uoride abstraction, forming decomposition products that inhibit the bulk electrodeposition of uranium metal. Similar results were found when the organic solvents were used with TBA[B(C{sub 6}F{sub 5}){sub 4}] as the supporting electrolyte, although the voltammetric data of uranium ions in these solutions is more encouraging in relation to electrodeposition of uranium metal. Preliminary results on the voltammetric behavior and bulk electrodeposition of plutonium species are also presented.

Stoll, Michael E [Los Alamos National Laboratory; Oldham, Warren J [Los Alamos National Laboratory; Costa, David A [Los Alamos National Laboratory

2008-01-01

240

Soft glassy colloidal arrays in an ionic liquid: colloidal glass transition, ionic transport, and structural color in relation to microstructure.  

PubMed

The colloidal glass transition, ionic transport, and optical properties of soft glassy colloidal arrays (SGCAs) that consist of poly(methyl methacrylate) (PMMA)-grafted silica nanoparticles (PMMA-g-NPs) and a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)amide ([C(2)mim][NTf(2)]), were investigated. At lower particle concentrations, PMMA-g-NPs were well-suspended in the IL without any aggregation or sedimentation, and the dilute suspensions showed liquid-like behavior. However, above a certain particle concentration, the suspensions became solidified and exhibited different structural colors depending on the particle concentrations. The liquid-solid transition of the SGCAs was essentially caused by colloidal glass transition. Due to the soft repulsive interaction between the particles, the effective volume fraction of the particle (?(eff)) required for colloidal glass transition was higher than that of the hard sphere system and found to be approximately 0.70-0.74. The SGCA had sufficient ionic conductivity, which was greater than 10(-3) S cm(-1) at room temperature, even in the highly concentrated region. For ionic transport of the cation and the anion in the SGCAs, the decrease in diffusivity observed with the addition of the particles (D(g)/D(0)) was slightly greater for the [NTf(2)] anion than that of the [C(2)mim] cation, suggesting that the [NTf(2)] anion preferentially interacts with the PMMA chains. The SGCAs showed homogeneous, nonbrilliant, and angle-independent structural colors above the glass transition volume fraction. In addition, the color of the SGCAs changed from red to green to blue as the particle concentration increased. A linear relationship was found between the maximum wavelength of the reflection spectra and the center-to-center distance in the SGCAs. PMID:20879726

Ueno, Kazuhide; Sano, Yuta; Inaba, Aya; Kondoh, Masashi; Watanabe, Masayoshi

2010-10-21

241

Solvent effects in ionic liquids: empirical linear energy-density relationships.  

PubMed

Multiparameter linear energy-density relationships to model solvent effects in room temperature ionic liquids (RTILs) are introduced and tested. The model incorporates two solvent dependent and two specific solute-solvent parameters represented by a set of electronic indexes derived from the conceptual density functional theory. The specific solute-solvent interactions are described in terms of the electronic chemical potential for proton migration between the anion or cation and the transition state structure of a specific reaction. These indexes provide a quantitative estimation of the hydrogen bond (HB) acceptor basicity and the hydrogen bond donor acidity of the ionic solvent, respectively. A sound quantitative scale of HB strength is thereby obtained. The solvent dependent contributions are described by the global electrophilicity of the cation and nucleophilicity of the anion forming the ionic liquid. The model is illustrated for the kinetics of cycloaddition of cyclopentadiene towards acrolein. In general, cation HB acidity outweighs the remaining parameters for this reaction. PMID:22711339

Cerda-Monje, A; Aizman, A; Tapia, R A; Chiappe, C; Contreras, R

2012-06-19

242

Ionic liquids as lubricants of polystyrene and polyamide 6-steel contacts. Preparation and properties of new polymer-ionic liquid dispersions  

Microsoft Academic Search

Room-temperature ionic liquids (ILs) have been used as external lubricants in polystyrene (PS) and polyamide 6 (PA6)-steel contacts and as internal lubricants in new polymer-IL dispersions. 1?C\\u000a n\\u000a H2n+1?3?CH3-imidazolium X? [X=BF4; n=2 (IL1), 6 (IL2), 8 (IL3). X=PF6; n=6 (IL4). X=CF3SO3; n=2 (IL5). X=(4?CH3C6H4SO3); n=2 (IL6)] ionic liquids give low friction and extremely mild wear in PS\\/AISI 316L stainless steel

J. Sanes; F. J. Carrión; M. D. Bermúdez; G. Martínez-Nicolás

2006-01-01

243

Ionic Liquids as Hypergolic Fuels (Postprint).  

National Technical Information Service (NTIS)

After seminal work presented a decade ago, ionic liquids (IL) have now received a lot of attention as energetic materials for propellant applications. In bipropellant rocket engines, it is desirable to achieve ignition by means of a hypergolic reaction an...

G. Vaghjiani M. Rosander S. Chambreau S. Schneider T. Hawkins

2008-01-01

244

Ionic liquid polyoxometalates as light emitting materials  

SciTech Connect

The low melting point, negligible vapor pressure, good solubility, and thermal and chemical stability make ionic liquids useful materials for a wide variety of applications. Polyoxometalates are early transition metal oxygen clusters that can be synthesized in many different sizes and with a variety of heterometals. The most attractive feature of POMs is that their physical properties, in particular electrical, magnetic, and optical properties, can be easily modified following known procedures. It has been shown that POMs can exhibit cooperative properties, as superconductivity and energy transfer. POM ionic liquids can be obtained by selecting the appropliate cation. Different alkyl ammonium and alkyl phosphonium salts are being used to produce new POM ionic liquids together with organic or inorganic luminescent centers to design light emitting materials. Ammonium and phosphonium cations with activated, polymerizable groups are being used to further polymerize the ionic liquid into transparent, solid materials with high metal density.

Ortiz-acosta, Denisse [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Scott, Brian [Los Alamos National Laboratory; Bennett, Bryan L [Los Alamos National Laboratory; Purdy, Geraldine M [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Mc Kigney, Edward [Los Alamos National Laboratory; Gilbertson, Robert [Los Alamos National Laboratory

2008-01-01

245

Friedel-Crafts Acylation of Aromatic Compounds in Ionic Liquids  

Microsoft Academic Search

This article first reviews the application of ionic liquids in Friedel-Crafts acylation reactions. Ionic liquids can be used as catalyst solvents, the active component on solid carriers, or just as the solvent. One advantage of using ionic liquids in acylation reactions is the enhanced reaction rates, conversion, and selectivity. The acylation mechanisms of aromatic compounds in ionic liquids are also

Z. C. Liu; X. H. Meng; R. Zhang; C. M. Xu

2009-01-01

246

Ionic Liquids as Extracting Agents for Heavy Metals  

Microsoft Academic Search

The development of applications of ionic liquids in extraction processes stretches back to the mid-1960s when the first studies on ionic liquid- based extractions were published. Since then, the interest of both academics and the industrial community on the development of ionic liquids-based technologies is continuously growing. The main driving force of ionic liquid engineering is to combine their “environmentally

Anja Stojanovic; Bernhard K. Keppler

2012-01-01

247

Ionic Liquids as Extracting Agents for Heavy Metals  

Microsoft Academic Search

The development of applications of ionic liquids in extraction processes stretches back to the mid-1960s when the first studies on ionic liquid- based extractions were published. Since then, the interest of both academics and industrial community on the development of ionic liquids-based technologies is continuously growing. The main driving force of ionic liquid engineering is to combine their “environmentally friendly”

Anja Stojanovic; Bernhard K. Keppler

2011-01-01

248

Superbase-derived protic ionic liquids  

DOEpatents

Protic ionic liquids having a composition of formula (A.sup.-)(BH.sup.+) wherein A.sup.- is a conjugate base of an acid HA, and BH.sup.+ is a conjugate acid of a superbase B. In particular embodiments, BH.sup.+ is selected from phosphazenium species and guanidinium species encompassed, respectively, by the general formulas: ##STR00001## The invention is also directed to films and membranes containing these protic ionic liquids, with particular application as proton exchange membranes for fuel cells.

Dai, Sheng; Luo, Huimin; Baker, Gary A.

2013-09-03

249

Study of thioglycosylation in ionic liquids.  

PubMed

A novel, green chemistry, glycosylation strategy was developed based upon the use of ionic liquids. Research studies demonstrated that thiomethyl glycosides could readily be activated with methyl trifluoromethane sulfonate, using 1-butyl-3-methylimidazolium tetrafluoroborate as a solvent. This green chemistry glycosylation strategy provided disaccharides with typical yields averaging 75%. The ionic liquid solvent could be readily reused for five sequential glycosylation reactions with no impact on product yield. PMID:16803635

Zhang, Jianguo; Ragauskas, Arthur

2006-06-27

250

Synthesis of benzylidenated hexopyranosides in ionic liquids.  

PubMed

The synthesis of 4,6-O-benzylidenated monosaccharides and disaccharides has been studied using ionic liquids as a unique solvent alternative. An examination of several imidazolium ionic liquids indicates that the benzylidenation of hexopyranosides in 3-butyl-1-methylimidazolium tetrafluoroborate, [bmim]BF4, gives the highest yields for most of the substrates, and that this solvent system could be readily recycled. PMID:16289411

Zhang, Jianguo; Ragauskas, Arthur J

2005-11-14

251

A novel CMPO-functionalized task specific ionic liquid: synthesis, extraction and spectroscopic investigations of actinide and lanthanide complexes.  

PubMed

A novel CMPO (carbamoylmethylphosphine oxide) based task specific ionic liquid (TSIL) with an NTf(2)(-) counter anion was synthesized and evaluated for actinide/lanthanide extraction from acidic feed solutions using several room temperature ionic liquids (RTILs). The extraction data were compared with those obtained with CMPO in the same set of RTILs and also in the molecular diluent, n-dodecane. The extracted species were analyzed by the conventional slope analysis method and the extraction followed an ion-exchange mechanism. The nature of bonding in the extracted complexes was investigated by various spectroscopic techniques such as FT-IR and UV-visible spectroscopy. PMID:23403959

Mohapatra, Prasanta K; Kandwal, Pankaj; Iqbal, Mudassir; Huskens, Jurriaan; Murali, Mallekav S; Verboom, Willem

2013-04-01

252

Room-temperature ductile carbides  

Microsoft Academic Search

Large-grained, oriented, polycrystalline samples of Ti3SiC2 loaded in compression at room temperature deform plastically. When the basal planes are oriented in such a way that allows\\u000a for slip, deformation occurs by the formation of shear bands. The minimum critical resolved shear stress at room temperature\\u000a is ?36 MPa. When the slip planes are parallel to the applied load—a situation where

M. W. Barsoum; T. El-Raghy

1999-01-01

253

High-temperature gating of solid-state nanopores with thermo-responsive macromolecular nanoactuators in ionic liquids.  

PubMed

Stimuli-responsive nanofluidic systems in room temperature ionic liquids (RTILs). The nanofluidic device can withstand high temperatures up to 200 °C, in which conventional water-based smart materials and nanodevices are invalid. The smart nanopores can be "irreversibly" turned off above the transition temperature of ca. 120-150 °C, actuated by the conformational change of the chemically-modified polymer brushes. PMID:22252937

Zhou, Yahong; Guo, Wei; Cheng, Jinsheng; Liu, Yang; Li, Jinghong; Jiang, Lei

2012-01-18

254

Influence of heat treatment on the micro\\/nano-tribological properties of ultra-thin ionic liquid films on silicon  

Microsoft Academic Search

The performance of micro- and nano-electromechanical systems (M\\/NEMS) depends on the surface and interface properties of the substrate, such as chemical composition, roughness, friction, adhesion, and wear. In order to solve these problems and improve the performance of M\\/NEMS, molecularly thin films of room temperature ionic liquid (RTIL)-1,3-di(2-hydroxyethyl)imidazolium hexafluorophosphate which has two terminal hydroxyl groups were prepared on silicon substrate.

Wenjie Zhao; Ying Wang; Liping Wang; Mingwu Bai; Qunji Xue

2010-01-01

255

Ionic Liquids for Utilization of Waste Heat from Distributed Power Generation Systems  

SciTech Connect

The objective of this research project was the development of ionic liquids to capture and utilize waste heat from distributed power generation systems. Ionic Liquids (ILs) are organic salts that are liquid at room temperature and they have the potential to make fundamental and far-reaching changes in the way we use energy. In particular, the focus of this project was fundamental research on the potential use of IL/CO2 mixtures in absorption-refrigeration systems. Such systems can provide cooling by utilizing waste heat from various sources, including distributed power generation. The basic objectives of the research were to design and synthesize ILs appropriate for the task, to measure and model thermophysical properties and phase behavior of ILs and IL/CO2 mixtures, and to model the performance of IL/CO2 absorption-refrigeration systems.

Joan F. Brennecke; Mihir Sen; Edward J. Maginn; Samuel Paolucci; Mark A. Stadtherr; Peter T. Disser; Mike Zdyb

2009-01-11

256

Synthesis and mesomorphic properties of rigid-core ionic liquid crystals.  

PubMed

Ionic liquid crystals combine the unique solvent properties of ionic liquids with self-organization found for liquid crystals. We report a detailed analysis of the structure-property relationship of a series of new imidazolium-based liquid crystals with an extended aromatic core. Investigated parameters include length and nature of the tails, the length of the rigid core, the lateral substitution pattern, and the nature of the counterion. Depending on the molecular structure, two mesophases were observed: a bilayered SmA2 phase and the more common monolayered SmA phase, both strongly interdigitated. Most materials show mesophases stable to high temperatures. For some cases, crystallization could be suppressed, and room-temperature liquid crystalline phases were obtained. The mesomorphic properties of several mixtures of ionic liquid crystals were investigated. Many mixtures showed full miscibility and ideal mixing behavior; however, in some instances we observed, surprisingly, complete demixing of the component SmA phases. The ionic liquid crystals and mixtures presented have potential applications, due to their low melting temperatures, wide temperature ranges, and stability with extra ion-doping. PMID:17949091

Kouwer, Paul H J; Swager, Timothy M

2007-10-20

257

Physicochemical Properties of Imidazolium-derived Ionic Liquids with Different C-2 Substitutions  

SciTech Connect

Five room temperature ionic liquids based on C-2 substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide (TFSI) anion were synthesized and their physicochemical properties: thermal property, density, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability were systematically investigated. The temperature dependence of both viscosity and ionic conductivities of these ionic liquids can be described by Vogel-Fulcher-Tamman (VFT) equation. Compared with the reference, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the introduction of functional groups at the C-2 position generally increased the viscosity and lowered the ionic conductivity. The introduction of ether group ( CH2OCH2CH2CH2CH3) at the C-2 position not only enhanced the reduction stability of the ionic liquids but also exhibited the lowest solid electrolyte interfacial resistance (RSEI). On the contrary, the introduction of a cyano group ( CN) at the C-2 position not only decreased the reduction stability but also adversely increased the SEI resistance. The effect of the C-2 substitution on the reduction stability was explained by the change of the energy level of the lowest unoccupied molecular orbital. The self-diffusion coefficients (D) of each ion were measured by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The lithium transference number (tLi) of 0.5 M LiTFSI/IL solutions calculated from the self-diffusion coefficients was in the range of 0.04 and 0.09.

Liao, Chen [ORNL; Shao, Nan [ORNL; Han, Kee Sung [ORNL; Sun, Xiao-Guang [ORNL; Jiang, Deen [ORNL; Hagaman, Edward {Ed} W [ORNL; Dai, Sheng [ORNL

2011-01-01

258

Evidence of secondary relaxations in the dielectric spectra of ionic liquids  

NASA Astrophysics Data System (ADS)

We investigated the dynamics of a series of room temperature ionic liquids based on the same 1-butyl-3-methyl imidazolium cation and different anions by means of broadband dielectric spectroscopy covering 15 decades in frequency (10-6-109Hz) , and in the temperature range from 400K down to 35K . Ionic conductivity is observed above the glass transition temperature Tg , and below, two relaxation processes appear, with the same features as the secondary relaxations typically observed in molecular glasses. The activation energy of the secondary processes of these ionic systems, and their dependence on the anion, are different. The slower process shows the characteristics of an intrinsic Johari-Goldstein relaxation, in particular an activation energy E?=24kBTg is found, as observed in molecular glasses.

Rivera, Alberto; Rössler, Ernst A.

2006-06-01

259

Single-walled carbon nanotubes modified by ionic liquid as antiwear additives of thermoplastics  

Microsoft Academic Search

Pristine single-walled carbon nanotubes (CNTs) were dispersed in the room-temperature ionic liquid (IL) 1-octyl, 3-methylimidazolium tetrafluoroborate ([OMIM]BF4) by grinding and ultrasounds. Excess IL was removed to obtain single-walled carbon nanotubes modified by [OMIM]BF4 (mCNTs). mCNTs were added in a 1wt.% to polystyrene (PS), polymethylmethacrylate (PMMA) and polycarbonate (PC) to obtain PS+mCNT, PMMA+mCNT and PC+mCNT. The dry tribological performance of the

F. J. Carrión; C. Espejo; J. Sanes; M. D. Bermúdez

2010-01-01

260

Electrochemical growth of hierarchical CuSn nanobrushes from an ionic liquid  

Microsoft Academic Search

One-step electrochemical synthesis of hierarchical single crystalline copper–tin nanobrushes is achieved in a room temperature 1-ethyl-3-methylimidazolium dicyanamide ionic liquid containing 0.016M Cu(I) and 0.033M Sn(II) at a low current density of ?0.4mAcm?2. This study also shows that morphologies of the deposits can be manipulated by the Cu(I)\\/Sn(II) concentrations in the solution, and thus, offers a method for reproducible preparation of

Yi-Ting Hsieh; I-Wen Sun

261

Volume Expansivities and Isothermal Compressibilities of Imidazolium and Pyridinium-Based Ionic Liquids  

Microsoft Academic Search

From ambient- and high-pressure density measurements, we report the volume expansivities and isothermal compressibilities of four room-temperature ionic liquids and 1-methylimidazole at temperatures between 298.2 and 343.2 K and pressures to 206.9 MPa. The compounds studied are 1-butyl-3- methylimidazolium hexafluorophosphate ((C4mim)(PF6)), 1-octyl-3-methylimidazolium hexafluorophos- phate ((C8mim)(PF6)), 1-octyl-3-methylimidazolium tetrafluoroborate ((C8mim)(BF4)), and N-butylpyri- dinium tetrafluoroborate ((NBuPy)(BF4)). The density is affected by the natures

Zhiyong Gu; Joan F. Brennecke

2002-01-01

262

The use of new ionic liquids in two-phase catalytic hydrogenation reaction by rhodium complexes  

Microsoft Academic Search

The reaction of 1-n-butyl-3-methylimidazolium chloride (BMIC) with sodium tetrafluoroborate or sodium hexafluorophosphate produced the room temperature-, air- and water-stable molten salts (BMI+)(BF4?) (1) and (BMI+)(PF6?) (2), respectively, in almost quantitative yield. The rhodium complexes RhCl(PPh3)3 and [Rh(cod)2][BF4] are completely soluble in these ionic liquids and they are able to catalyse the hydrogenation of cyclohexene at 10 atm and 25°C in

Paulo A. Z. Suarez; Jeane E. L. Dullius; Sandra Einloft; Roberto F. De Souza; Jairton Dupont

1996-01-01

263

Room Temperature Ionic Liquids as Replacements for Traditional Organic Solvents and their Applications Towards “Green Chemistry” in Separation Processes  

Microsoft Academic Search

\\u000a The full effect of Green Chemistry will be realized when the words “environmentally friendly” and “chemistry” can be used\\u000a in the same sentence without seeming to be a contradiction. In an effort to comply with governmental regulations and to spruce\\u000a up the image of the chemical industry, one of the major goals of “green” chemistry is to prevent pollution and

Ann E. Visser; Richard P. Swatloski; W. Matthew Reichert; Heather D. Willauer; Jonathan G. Huddleston; Robin D. Rogers

264

Synthesis and Characterization of Novel Chiral Ionic Liquids and Investigation of their Enantiomeric Recognition Properties  

PubMed Central

We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L- and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L-and D-alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L- and D-alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263°C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state 19F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L- and D-alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion.

BWAMBOK, DAVID K.; MARWANI, HADI M.; FERNAND, VIVIAN E.; FAKAYODE, SAYO O.; LOWRY, MARK; NEGULESCU, IOAN; STRONGIN, ROBERT M.; WARNER, ISIAH M.

2009-01-01

265

Surface Nanocrystallization of an Ionic Liquid  

SciTech Connect

Surface crystallization at the vapor-liquid interface of the ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) is observed in synchrotron x-ray diffraction studies. Sharp Bragg reflections emerge in grazing-angle x-ray diffraction patterns 37 C above the bulk melting temperature, indicating the presence of a long-range ordered phase at the surface in coexistence with the bulk parent liquid. The unique structure of the vapor-liquid interface where butyl chains attached to the cations are expelled to the vapor side facilitates interionic electrostatic interactions that lead to the crystallization. Our results demonstrate the complexity of ionic-liquid structure with their tendency to spontaneously phase separate into nanodomains with finite correlation lengths in coexistence with the liquid phase. By virtue of interfacial boundary conditions, these nanodomains grow laterally to form quasi-two-dimensional crystals.

Jeon, Yoonnam; Vaknin, David; Bu, Wei; Sung, Jaeho; Ouchi, Yukio; Sung, Woongmo; Kim, Doseok (Iowa State); (Nagoya); (Sogang)

2012-03-26

266

Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids  

SciTech Connect

Self-aggregation in room temperature ionic liquids (RTILs) has been a subject of intense interest in recent years. In this work, we provide new experimental evidence for chain length-dependent self-aggregation in RTILs using fluorescence correlation spectroscopy (FCS). In studying a homologous series of N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, [CnMPy][Tf2N] RTILs of varying alkyl chain length (n = 3, 4, 6, 8, and 10), biphasic rhodamine 6G solute diffusion dynamics were observed; both the fast and slow diffusion coefficients decrease with increasing alkyl chain length, with the relative contribution from slower diffusion increasing for longer-chained [CnMPy][Tf2N]. We propose that the biphasic diffusion dynamics originate from self-aggregation of the nonpolar alkyl chains in the cationic [CnMPy]+. The presence of this local liquid structuring provides important insight into the behavior of RTILs relevant to their application in photovoltaics, fuel cells, and batteries.

Guo, Jianchang [ORNL; Baker, Gary A [ORNL; Hillesheim, Patrick C [ORNL; Dai, Sheng [ORNL; Shaw, Robert W [ORNL; Mahurin, Shannon Mark [ORNL

2011-01-01

267

Modification and implications of changes in electrochemical responses encountered when undertaking deoxygenation in ionic liquids.  

PubMed

Physicochemical changes and substantially modified electrochemical behavior have been reported when ionic liquids are degassed with nitrogen. In conventional experiments in aqueous and organic media, degassing with N(2) is commonly used to remove the electroactive dissolved oxygen. However, in hydrophilic ionic liquid media, degassing with N(2) removes not only the dissolved oxygen but also a significant amount of the adventitious water present. Given the low viscosity of water, this in turn leads to a dramatic change of the viscosity of the degassed ionic liquid and hence mass transport properties that influence voltammetric responses. In the widely used and relatively viscous room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF(4)) containing the redox probe tetracyanoquinodimethane (TCNQ) and 9% (v/v) deliberately added water, 1 h degassing with very dry N(2) under benchtop conditions results in a dramatic decrease of the TCNQ reduction current obtained under steady-state conditions at a 1 mum diameter microdisc electrode. This is reflected by a change of diffusion coefficient of TCNQ (D(TCNQ)) from 2.6 x 10(-7) to 4.6 x 10(-8) cm(2) s(-1). Karl Fischer titration measurements show that almost complete removal of the deliberately added 9% water is achieved by degassing under benchtop conditions. However, displacement of oxygen by nitrogen in the ionic liquid solution results in the decrease of electrochemical reduction current by 6%, implying that dissolved gases need not be inert with respect to solvent properties. Oxygen removal by placing the BMIMBF(4) ionic liquid in a nitrogen-filled glovebox or in a vacuum cell also simultaneously leads to removal of water and alteration of voltammetric data. This study highlights that (i) important physicochemical differences may arise upon addition or removal of a solute from viscous ionic liquids; (ii) degassing with dry nitrogen removes water as well as oxygen from ionic liquids, which may have implications on the viscosity and structure of the medium; (iii) particular caution must be exercised when deoxygenation is applied in ionic liquid media as part of the protocol used in electrochemical experiments to remove oxygen; (iv) gases such as oxygen, argon, and nitrogen dissolved in ionic liquids need not be innocent with respect to the properties of an ionic liquid. The use of vacuum based techniques to eliminate all volatile solutes, including water and oxygen, is advocated. PMID:20392069

Zhao, Chuan; Bond, Alan M; Compton, Richard G; O'Mahony, Aoife M; Rogers, Emma I

2010-05-01

268

Energy Efficient Electrochromic Windows Incorporating Ionic Liquids  

SciTech Connect

One approach to increasing the energy efficiency of windows is to control the amount of solar radiation transmitted through a window by using electrochromic technology. What is unique about this project is that the electrochromic is based on the reduction/oxidation reactions of cathodic and anodic organic semi-conducting polymers using room temperature ionic liquids as ion transport electrolytes. It is believed that these types of coatings would be a lower cost alternative to traditional all inorganic thin film based electrochromic technologies. Although there are patents1 based on the proposed technology, it has never been reduced to practice and thoroughly evaluated (i.e. durability and performance) in a window application. We demonstrate that by using organic semi-conductive polymers, specific bands of the solar spectrum (specifically visible and near infrared) can be targeted for electrochemical variable transmittance responsiveness. In addition, when the technology is incorporated into an insulating glass unit, the energy parameters such as the solar heat gain coefficient and the light to solar gain ratio are improved over that of a typical insulating glass unit comprised of glass with a low emissivity coating. A minimum of {approx}0.02 quads of energy savings per year with a reduction of carbon emissions for electricity of {approx}320 MKg/yr benefit is achieved over that of a typical insulating glass unit including a double silver low-E coating. Note that these values include a penalty in the heating season. If this penalty is removed (i.e. in southern climates or commercial structures where cooling is predominate year-round) a maximum energy savings of {approx}0.05 quad per year and {approx}801 MKg/yr can be achieved over that of a typical insulating glass unit including a double silver low-E coating. In its current state, the technology is not durable enough for an exterior window application. The primary downfall is that the redox chemistry fails to recover to a bleached state upon exposure to heat and solar radiation while being cycled over time from the bleached to the dark state. Most likely the polymers are undergoing degradation reactions which are accelerated by heat and solar exposure while in either the reduced or oxidized states and the performance of the polymers is greatly reduced over time. For this technology to succeed in an exterior window application, there needs to be more work done to understand the degradation of the polymers under real-life application conditions such as elevated temperatures and solar exposure so that recommendations for improvements in to the overall system can be made. This will be the key to utilizing this type of technology in any future real-life applications.

Cheri Boykin; James Finley; Donald Anthony; Julianna Knowles; Richard Markovic; Michael Buchanan; Mary Ann Fuhry; Lisa Perrine

2008-11-30

269

Room temperature terahertz polariton emitter  

SciTech Connect

Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.

Geiser, Markus; Scalari, Giacomo; Castellano, Fabrizio; Beck, Mattias; Faist, Jerome [Institute for Quantum Electronics, ETH Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich (Switzerland)

2012-10-01

270

Ionic liquids as active pharmaceutical ingredients.  

PubMed

Ionic liquids (ILs) are ionic compounds that possess a melting temperature below 100 °C. Their physical and chemical properties are attractive for various applications. Several organic materials that are now classified as ionic liquids were described as far back as the mid-19th century. The search for new and different ILs has led to the progressive development and application of three generations of ILs: 1) The focus of the first generation was mainly on their unique intrinsic physical and chemical properties, such as density, viscosity, conductivity, solubility, and high thermal and chemical stability. 2) The second generation of ILs offered the potential to tune some of these physical and chemical properties, allowing the formation of "task-specific ionic liquids" which can have application as lubricants, energetic materials (in the case of selective separation and extraction processes), and as more environmentally friendly (greener) reaction solvents, among others. 3) The third and most recent generation of ILs involve active pharmaceutical ingredients (API), which are being used to produce ILs with biological activity. Herein we summarize recent developments in the area of third-generation ionic liquids that are being used as APIs, with a particular focus on efforts to overcome current hurdles encountered by APIs. We also offer some innovative solutions in new medical treatment and delivery options. PMID:21557480

Ferraz, Ricardo; Branco, Luís C; Prudêncio, Cristina; Noronha, João Paulo; Petrovski, Zeljko

2011-05-09

271

Disclosure of the imidazolium cation coordination and stabilization mode in ionic liquid stabilized gold(0) nanoparticles.  

PubMed

A surface-enhanced Raman spectroscopy (SERS) study of imidazolium ionic liquid stabilized gold(0) nanoparticles (GNPs) furnished previously unknown knowledge about the coordination and stabilization mode of the imidazolium cation. GNPs were prepared by hydrazine reduction of a chloroauric acid solution in 1-triethylene glycol monomethyl ether-3-methylimidazolium methanesulfonate 2 as ether-functionalized room-temperature ionic liquid (RTIL). UV-vis spectroscopy showed the presence of GNP aggregates as absorptions extended to the NIR region. A parallel coordination mode for the imidazolium cation of RTIL 2 on the GNP surface was observed by SERS, which occurred without the simultaneous coordination of the 1-triethylene glycol monomethyl ether-functionality. Instead of this, the ether-functionality was directed away from the GNP surface and acted as steric barrier between the GNPs/GNP aggregates, thus preventing further aggregation. These new insights suggest that the imidazolium cation is responsible for electrosteric stabilization. PMID:17761189

Schrekker, Henri S; Gelesky, Marcos A; Stracke, Marcelo P; Schrekker, Clarissa M L; Machado, Giovanna; Teixeira, Sergio R; Rubim, Joel C; Dupont, Jairton

2007-08-14

272

Synthesis and characterisations of Aliquat 336® and cetylpyridinium ionic liquids incorporated with sulfonate-based anions  

NASA Astrophysics Data System (ADS)

A novel series of ionic liquids based on the tricaprylmethylammonium cation [C25H54N+], in Aliquat 336® and cetylpyridinium cation [C21H38N+] in cetylpyridinium chloride incorporating sulfonate-based anions were elegantly prepared by means of ion exchange between the Cl- cation with two different anions, namely, dioctylsulfosuccinate [DOSS-] and dihexylsulfosuccinate [HOSS-]. These ionic liquids were characterised using FTIR-ATR and NMR in order to identify the molecular structures of these compounds. The physical properties of these compounds, namely refractive index and thermal properties were measured at room temperature and are reported herein. ILs incorporating cetylpyridinium cations show higher thermal stability and refractive index values as compared to Aliquat ILs due to the effects of the aromatic ring on the cetylpyridinium cation as well as the longer alkyl chain on the anion of DOSS.

Wilfred, Cecilia Devi; Nair, G. Divya; Ziyada, Abobakr Khidir

2012-09-01

273

Molecular mechanism of gas adsorption into ionic liquids: A molecular dynamics study  

SciTech Connect

Room temperature ionic liquids (RTILs) have been shown to be versatile and tunable solvents that can be used in many chemical applications. In this study, we developed a dynamical, molecular-scale picture of the gas dissolution and interfacial processes in RTILs using molecular simulations. These simulations can provide the free energies associated with transporting a gas solute across various RTIL interfaces and physical insights into the interfacial properties and transport molecular mechanism of gas sorption processes. For CO2 sorption, the features in the potential of mean force (PMF) of CO2 using both polarizable and non-polarizable force fields are similar qualitatively. However, we observed some quantitative differences, and we describe the causes of these differences in this paper. We also show the significant impact of ionic-liquid chemical structures on the gas sorption process, and we discuss their influence on the H2O transport mechanism.

Dang, Liem X.; Chang, Tsun-Mei

2012-01-19

274

Ionic liquid-stabilized non-spherical gold nanofluids synthesized using a one-step method  

PubMed Central

Ionic liquid (IL)-stabilized non-spherical gold nanofluids have been synthesized by a one-step method in aqueous solution. The whole reaction proceeded in room temperature. In the presence of amino-functionalized ionic liquids, gold nanofluids with long-wave surface plasmon resonance (SPR) absorption (>600 nm) could be obtained by adopting tannic acid as the reductant. The specific SPR absorption was related to the non-spherical gold nanoparticles including gold triangle, decahedra, and icosahedra nanocrystals. All the nanocrystals were observed by transmission electron microscopy. It was deduced that the formation of non-spherical gold nanofluids was related to the hydroxyls in tannic acid while IL acted as the synthesis template.

2012-01-01

275

Capacitive Energy Storage from - 50o to 100o Using an Ionic Liquid Electrolyte  

SciTech Connect

Relying on redox reactions, most batteries are limited in their ability to operate at very low or very high temperatures. While performance of electrochemical capacitors is less dependent on the temperature, present-day devices still cannot cover the entire range needed for automotive and electronics applications under a variety of environmental conditions. We show that the right combination of the exohedral nanostructured carbon (nanotubes and onions) electrode and a eutectic mixture of ionic liquids can dramatically extend the temperature range of electrical energy storage, thus defying the conventional wisdom that ionic liquids can only be used as electrolytes above room temperature. We demonstrate electrical double layer capacitors able to operate from 50 to 100 C over a wide voltage window (up to 3.7 V) and at very high charge/discharge rates of up to 20 V/s.

Lin, Rongying [Universite Paul Sabatier, Toulouse Cedex, France.; Taberna, Pierre-Louis [Universite Paul Sabatier, Toulouse Cedex, France.; Santini, Sebastien [SOLVIONIC Company, Toulouse, France; Presser, Volker [ORNL; Perez, Carlos R. [Drexel University; Malbosc, Francois [SOLVIONIC Company, Toulouse, France; Rupesinghe, Nalin L. [AIXTRON, Cambridge, UK; Teo, Kenneth B. K. [AIXTRON, Cambridge, UK; Gogotsi, Yury G. [Drexel University; Simon, Patrice [Universite Paul Sabatier, Toulouse Cedex, France.

2011-01-01

276

Nonaqueous microemulsions based on n,n'-alkylimidazolium alkylsulfate ionic liquids.  

PubMed

The ternary system composed of the ionic liquid surfactant (IL-S) 1-butyl-3-methylimidazolium dodecylsulfate ([Bmim][DodSO4]), the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]), and toluene has been investigated. Three major mechanisms guiding the structure of the isotropic phase were identified by means of conductometric experiments, which have been correlated to the presence of oil-in-IL, bicontinuous, and IL-in-oil microemulsions. IL-S forms micelles in toluene, which swell by adding RTIL as to be shown by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) experiments. Therefore, it is possible to form water-free IL-in-oil reverse microemulsions ?10 nm in size as a new type of nanoreactor. PMID:23679228

Rojas, Oscar; Tiersch, Brigitte; Rabe, Christian; Stehle, Ralf; Hoell, Armin; Arlt, Bastian; Koetz, Joachim

2013-05-28

277

Simultaneous Design of Ionic Liquids and Azeotropic Separation Processes  

Microsoft Academic Search

A methodology for the design of azeotrope separation processes using ionic liquids as entrainers is outlined. A Hildebrand solubility parameter group contribution model has been developed to screen for or design an ionic liquid entrainer that is soluble with the azeotropic components. Using the best candidate, vapor-liquid equilibria data is predicted using a new ionic liquid UNIFAC model that has

Brock C. Roughton; John White; Kyle V. Camarda; Rafiqul Gani

2011-01-01

278

Ionic polymer-metal composites (IPMCs) containing Cu/Ni electrodes and ionic liquids for durability  

NASA Astrophysics Data System (ADS)

We describe the fabrication of ionic polymer-meal composites (IPMCs) containing Cu/Ni electrode as an electrode material and ionic liquid as an electrolyte. Cu/Ni is notorious for vulnerability to oxidation and acid. The authors have investigated best candidate of ionic liquids for this vulnerable electrode. This new IPMC shows increased displacement and blocking force compared to that of conventional IPMC containing Pt electrode and ionic liquid due to increased stiffness of resulting IPMC and size effect of mobile cations. In this research, the effect of ionic liquid was investigated by monitoring displacement and blocking force of IPMCs depending on the type of ionic liquids.

Lee, Hyung-Kun; Choi, Nak-Jin; Jung, Sunkyung; Park, Kang-Ho; Kim, Jongdae

2009-05-01

279

General impossibility to 'prescribe' diffusion for a geminate pair in a central force field and peculiarities of geminate in ionic liquids.  

SciTech Connect

Given the difficulty of obtaining analytical solutions for the diffusion of interacting geminate pairs of (ion) radicals in liquids, it is common, following the original treatment of Mozumder, to 'prescribe' this diffusion. A demonstration is given that such a prescription is impossible for any interaction potential other than the Coulomb potential. This demonstration suggests the inadequacy of this common approach to modeling geminate pair and spur dynamics in the largest emerging class of organic solvents: room-temperature ionic liquids.

Shkrob, I. A. (Chemical Sciences and Engineering Division)

2011-05-12

280

Organic electrical double layer transistors gated with ionic liquids  

NASA Astrophysics Data System (ADS)

Transport in organic semiconductors gated with several types of ionic liquids has been systematically studied at charge densities larger than 10^13 cm-2. We observe a pronounced maximum in channel conductance for both p-type and n-type organic single crystals which is attributed to carrier localization at the semiconductor-electrolyte interface. Carrier mobility, as well as charge density and dielectric capacitance are determined through displacement current measurement and capacitance-voltage measurement. By using a larger-sized and spherical anion, tris(pentafluoroethyl)trifluorophosphate (FAP), effective carrier mobility in rubrene can be enhanced substantially up to 3.2 cm^2V-1s-1. Efforts have been made to maximize the charge density in rubrene single crystals, and at low temperature when higher gate bias can be applied, charge density can more than double the amount of that at room temperature, reaching 8*10^13 cm-2 holes (0.4 holes per rubrene molecule).

Xie, Wei; Frisbie, C. Daniel

2011-03-01

281

Complex Capacitance Scaling in Ionic Liquids-Filled Nanopores  

SciTech Connect

Recent experiments have shown that the capacitance of subnanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulations, we show that the capacitance of slit-shaped nanopores in contact with room-temperature ionic liquids exhibits a U-shaped scaling behavior in pores with widths from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus reproduces the experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. The overall U-shaped scaling behavior provides insights on the origins of the difficulty in experimentally observing the pore-width-dependent capacitance. We establish a theoretical framework for understanding the capacitance of electrical double layers in nanopores and provide mechanistic details into the origins of the observed scaling behavior. The framework highlights the critical role of 'ion solvation' in controlling pore capacitance and the importance of choosing anion/cation couples carefully for optimal energy storage in a given pore system.

Sumpter, Bobby G [ORNL

2011-01-01

282

Complex Capacitance Scaling in Ionic Liquids-filled Nanopores  

SciTech Connect

Recent experiments have shown that the capacitance of sub-nanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulations, we show that the capacitance of slit-shaped nanopores in contact with room-temperature ionic liquids exhibits a U-shaped scaling behavior in pores with width from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus reproduces the experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. The overall U-shaped scaling behavior provides insights on the origins of the difficulty in experimentally observing the pore-width dependent capacitance. We establish a theoretical framework for understanding the capacitance of electrical double layers in nanopores and provide mechanistic details into the origins of the observed scaling behavior. The framework highlights the critical role of ion solvation in controlling pore capacitance and the importance of choosing anion/cation couples carefully for optimal energy storage in a given pore system.

Qiao, Rui [Clemson University; Huang, Jingsong [ORNL; Meunier, Vincent [ORNL; Sumpter, Bobby G [ORNL; Peng, Wu [Clemson University

2011-01-01

283

Thermoresponsive poly(ionic liquid) hydrogels.  

PubMed

A new series of LCST ILs have been copolymerised with crosslinkers of varying length to afford the first ever thermoresponsive poly(ionic liquid)-based hydrogels. These hydrogels exhibit surprisingly broad LCST and volume transition behaviour compared to standard thermoresponsive gels and linear ILs. PMID:24064665

Zió?kowski, Bartosz; Diamond, Dermot

2013-10-01

284

Magnetorheological solid composites based on ionic liquids  

Microsoft Academic Search

A new method for the preparation of magnetorheological elastomers or solid composites with intriguing properties is presented. The method makes use of magnetorheological fluids formed by micron-sized magnetic particles dispersed in ionic liquids. These dispersions are combined with suitable polymers to obtain novel magnetoresponsive solid materials which may find interesting applications, for instance, as actuators, in diverse fields of science

Carlos Guerrero-Sanchez; Corine Fabrie; Ulrich S. Schubert

2009-01-01

285

Synthesis and properties of alkoxy- and alkenyl-substituted peralkylated imidazolium ionic liquids.  

PubMed

Novel peralkylated imidazolium ionic liquids bearing alkoxy and/or alkenyl side chains have been synthesized and studied. Different synthetic routes towards the imidazoles and the ionic liquids comprising bromide, iodide, methanesulfonate, bis(trifluoromethylsulfonyl)imide ([NTf2 ](-) ), and dicyanamide {[N(CN)2 ](-) } as the anion were evaluated, and this led to a library of analogues, for which the melting points, viscosities, and electrochemical windows were determined. Incorporation of alkenyl moieties hindered solidification, except for cations with high symmetry. The alkoxy-derivatized ionic liquids are often crystalline; however, room-temperature ionic liquids (RTILs) were obtained with the weakly coordinating anions [NTf2 ](-) and [N(CN)2 ](-) . For the viscosities of the peralkylated RTILs, an opposite trend was found, that is, the alkoxy derivatives are less viscous than their alkenyl-substituted analogues. Of the crystalline compounds, X-ray diffraction data were recorded and related to their molecular properties. Upon alkoxy substitution, the electrochemical cathodic limit potential was found to be more positive, whereas the complete electrochemical window of the alkenyl-substituted imidazolium salts was shifted to somewhat more positive potentials. PMID:24115685

Maton, Cedric; Brooks, Neil R; Van Meervelt, Luc; Binnemans, Koen; Schaltin, Stijn; Fransaer, Jan; Stevens, Christian V

2013-09-23

286

A new series of ionic liquids based on the difluorophosphate anion.  

PubMed

A new series of ionic liquids based on the difluorophosphate anion (PO(2)F(2)(-)) has been synthesized by metathesis from the corresponding chloride. Incorporation of the PO(2)F(2)(-) anion with an N-heterocyclic cation (1-ethyl-3-methylimidazolium (EMIm(+)), 1-butyl-3-methylimidazolium, 1-butyl-1-methylpyrrolidinium, or 1-butyl-1-methylpiperidinium (BMPip(+))) produces ionic liquids with low melting points, including some room-temperature ionic liquids. The vibrational frequencies of PO(2)F(2)(-) in the obtained ionic liquids were assigned with the aid of quantum mechanical calculations. The ionic conductivities of the ionic liquids are comparable to those of the corresponding tetrafluoroborate-based ionic liquids (e.g., 12 mS cm(-1) for 1-ethyl-3-methylimidazolium difluorophosphate, [EMIm][PO(2)F(2)]). The stability of ionic liquids against hydrolysis is significantly improved by replacing the hexafluorophosphate anion with the difluorophosphate anion, which suppresses the subsequent liberation of hydrogen fluoride. According to the solvatochromic method, the donor ability of ionic liquids based on PO(2)F(2)(-) is stronger than those of ionic liquids based on BF(4)(-), PF(6)(-), and N(SO(2)CF(3))(2)(-), due to the large negative charge on the oxygen atoms in PO(2)F(2)(-). The electrochemical window of [EMIm][PO(2)F(2)] is around 4.2 V, and the diffusion coefficients of ferrocene in [EMIm][PO(2)F(2)] are 2.83 x 10(-7) cm(2) s(-1) by cyclic voltammetry and 3.03 x 10(-7) cm(2) s(-1) by chronoamperometry, both of which are comparable to those in 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm][BF(4)]). The X-ray structure of [BMPip][PO(2)F(2)] contains two cations and two anions in the asymmetric unit, where one of the two cations is disordered into two positions (chair configurations) even at -173 degrees C. The oxygen atoms in PO(2)F(2)(-) have closer contacts to the hydrogen atoms in BMPip(+) than the fluorine atoms, indicative of their stronger basicity. PMID:19580312

Matsumoto, Kazuhiko; Hagiwara, Rika

2009-08-01

287

Static gas-liquid interfacial direct current discharge plasmas using ionic liquid cathode  

SciTech Connect

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we have succeeded in creating the static and stable gas (plasmas)-liquid (ionic liquids) interfacial field using a direct current discharge under a low gas pressure condition. It is clarified that the ionic liquid works as a nonmetal liquid electrode, and furthermore, a secondary electron emission coefficient of the ionic liquid is larger than that of conventional metal electrodes. The plasma potential structure of the gas-liquid interfacial region, and resultant interactions between the plasma and the ionic liquid are revealed by changing a polarity of the electrode in the ionic liquid. By utilizing the ionic liquid as a cathode electrode, the positive ions in the plasma region are found to be irradiated to the ionic liquid. This ion irradiation causes physical and chemical reactions at the gas-liquid interfacial region without the vaporization of the ionic liquid.

Kaneko, T. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan); CREST/JST, Tokyo 102-0075 (Japan); Baba, K.; Hatakeyama, R. [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan)

2009-05-15

288

Surface-functionalized ionic liquid crystal-supported ionic liquid phase materials: ionic liquid crystals in mesopores.  

PubMed

The influence of confinement on the ionic liquid crystal (ILC) [C(18)C(1)Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si-based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid-to-liquid-crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid-crystalline-to-liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid-to-liquid-crystalline phase transition observed for the neat ILC. For applications within the "supported ionic liquid phase (SILP)" concept, the experiments show that in pores of diameter 50 nm a pore filling of ?>0.4 is sufficient to reproduce the phase transitions of the neat ILC. PMID:22069236

Kohler, Florian T U; Morain, Bruno; Weiss, Alexander; Laurin, Mathias; Libuda, Jörg; Wagner, Valentin; Melcher, Berthold U; Wang, Xinjiao; Meyer, Karsten; Wasserscheid, Peter

2011-11-08

289

Checkerboard Self-Patterning of an Ionic Liquid Film on Mercury  

SciTech Connect

{angstrom}-resolution studies of room temperature ionic liquid (RTIL) interfaces are scarce, in spite of their long-recognized importance for the science and many applications of RTILs. We present an {angstrom}-resolution x-ray study of a Langmuir film of an RTIL on mercury. At low (high) coverage [90 (50) {angstrom}{sup 2}/molecule] a mono-(bi)layer of surface-parallel molecules is found. The molecules self-assemble in a lateral ionic checkerboard pattern, unlike the uniform-charge, alternate-ion layers of this RTIL at its bulk-solid interface. A 2D-smectic order is found, with molecules packed in parallel stripes, forming long-range order normal to, but none along, the stripes.

L Tamam; B Ocko; H Reichert; M Deutsch

2011-12-31

290

Checkerboard Self-Patterning of an Ionic Liquid Film on Mercury  

SciTech Connect

{angstrom}-resolution studies of room temperature ionic liquid (RTIL) interfaces are scarce, in spite of their long-recognized importance for the science and many applications of RTILs. We present an {angstrom}-resolution x-ray study of a Langmuir film of an RTIL on mercury. At low (high) coverage [90 (50) {angstrom}{sup 2}/molecule] a mono-(bi)layer of surface-parallel molecules is found. The molecules self-assemble in a lateral ionic checkerboard pattern, unlike the uniform-charge, alternate-ion layers of this RTIL at its bulk-solid interface. A 2D-smectic order is found, with molecules packed in parallel stripes, forming long-range order normal to, but none along, the stripes.

Ocko, B.M.; Tamam, L.; Reichert, H.; Deutsch, M.

2011-05-10

291

Novel room temperature ferromagnetic semiconductors  

SciTech Connect

Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

Gupta, Amita

2004-11-01

292

Ionic liquids as surfactants in micellar liquid chromatography.  

PubMed

This paper is devoted to application of ionic liquids as surfactants in LC of organic compounds, derivatives of 1,4-thiosemicarbazides. According to HPLC requirements the most advantageous conditions such as transparency for ultraviolet light, low CMC, additional inorganic salt additives, and appropriate organic solvent were established. The CMC was determined using conductivity measurements. Suitability of two different stationary phases: RP-C18 and cyanopropyl bonded phase was examined under micellar conditions. Chosen ionic liquid surfactant was compared to common traditional amphiphilic reagent - SDS. Elaborated on chromatographic micellar conditions were tested as a pilot technique for prediction of distribution coefficients of organic analytes in ionic liquid-based aqueous two-phase system. PMID:23609988

Flieger, Jolanta; Siwek, Agata; Pizo?, Magdalena; Czajkowska-?elazko, Anna

2013-04-23

293

Structure and Thermodynamics of Block Copolymers Doped with Ionic Liquids  

NASA Astrophysics Data System (ADS)

Incorporation of ionic liquids into block copolymers is of interest for applications such as high temperature fuel cell membranes and polymer processing. These applications take advantage of ionic liquids' attractive physiochemical properties, such as low vapor pressure and high thermal stability. We investigate the structure and thermodynamics of poly(styrene-b-2-vinylpyridine) (PS-PVP) block copolymers doped with an ionic liquid consisting of imidazole and bis(trifluoromethanesulfonyl)amide (HFTSI). Using small angle X-ray scattering (SAXS), we demonstrate that increased ionic liquid doping leads to swelling of lamellar nanodomains in a symmetric PS-PVP block copolymer. At high ionic liquid loadings, we observe break up of the lamellar domains into hexagonally perforated lamellae. We characterize the effect of ionic liquid loading on the order-disorder transition (ODT) temperature of PS-PVP. We observe depression of the PS-PVP ODT temperature with increasing loading of the ionic liquid.

Virgili, J. M.; Balsara, N. P.; Segalman, R. A.

2008-03-01

294

1,10-Phenanthrolinium ionic liquid crystals.  

PubMed

The 1,10-phenanthrolinium cation is introduced as a new building block for the design of ionic liquid crystals. 1,10-Phenanthroline, 5-methyl-1,10-phenanthroline, 5-chloro-1,10-phenanthroline, and 4,7-diphenyl-1,10-phenanthroline were quaternized by reaction with 1,3-dibromopropane or 1,2-dibromoethane. The resulting cations were combined with dodecyl sulfate or dioctyl sulfosuccinate anions. The influence of both the cation and anion type on the thermal behavior was investigated. Several of the complexes exhibit mesomorphic behavior, with smectic E phases for the dodecyl sulfate salts and smectic A phases for the dioctyl sulfosuccinate salts. Structural models for the packing of the 1,10-phenanthrolinium and anionic moieties in the liquid-crystalline phases are presented. The ionic compounds show fluorescence in the solid state and in solution. PMID:21250740

Cardinaels, Thomas; Lava, Kathleen; Goossens, Karel; Eliseeva, Svetlana V; Binnemans, Koen

2011-01-20

295

Functional ionic liquids for hydrolysis of lignocellulose.  

PubMed

An efficient system for hydrolysis of lignocellulosic materials to prepare reducing sugar in a series of functional acidic ionic liquids with low synthetic cost and excellent dissolved and catalytic activity was established. High yield of reducing sugar was obtained with the use of 1-H-3-methylimidazolium chloride ([HMIM]Cl). The use of ionic liquid under ultrasound irradiation greatly improved the yield of total reducing sugar. The optimum reaction conditions were as follows: ratio of water/sample was 5 (w/w), ratio of IL/sample was 25 (w/w), 70°C, 120 min and the yield of reducing sugar was up to 53.27 mg from 0.2g of soybean straw and 50.03 mg from 0.2g of corn straw. PMID:23769534

Hu, Xiaomei; Xiao, Yibo; Niu, Kun; Zhao, Yang; Zhang, Bixian; Hu, Baozhong

2013-04-30

296

Solubilities and thermophysical properties of ionic liquids  

Microsoft Academic Search

This report presents the systematic study on the solubilities of 1-alkyl-3-methyl- imidazolium hexafluorophosphate (e, or bmim)(PF 6 ), 1-alkyl-3-methylimidazolium methylsulfate (almim)(CH 3 SO 4 ), 1-hexyloxymethyl-3-methylimidazolium ionic liquids (ILs) (C 6 H 13 OCH 2 mim)(BF 4 ), or (C 6 H 13 OCH 2 mim)((CF 3 SO 2 ) 2 N) in aliphatic hydrocar- bons (heptane, octane), cyclohydrocarbons (cyclopentane,

Urszula Domanska

2005-01-01

297

Acetylation of ?-chitin in ionic liquids  

Microsoft Academic Search

Acetylation of ?-chitin using acetic anhydride in an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), was performed. First, a mixture of chitin and AMIMBr (2% w\\/w) was heated at 100°C for 24h for dissolution. Then, acetic anhydride (5–20equiv) was added to the solution and the mixture was heated with stirring at desired temperatures for 24h. The product was precipitated by the addition

Shozaburo Mine; Hironori Izawa; Yoshiro Kaneko; Jun-ichi Kadokawa

2009-01-01

298

A new cluster-ion-beam source for secondary ion mass spectrometry (SIMS) using the electrospray of a pure ionic liquid under high vacuum  

NASA Astrophysics Data System (ADS)

Electrospray characteristics were studied using a pure room-temperature molten salt (i.e., an ionic liquid) at pressures around 10-5 Pa as well as at atmospheric pressure. The ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide was tested, which has negligible vapor pressure and high conductivity. During electrospray, the ionic liquid was introduced at a constant flow rate into a stainless-steel capillary (i.d. 30 ?m). It was demonstrated that stable electrosprayed currents exceeding ±1 ?? were continuously produced in both positive and negative modes. The electrosprayed currents in a high vacuum were twice those at atmospheric pressure. It was found that gas pressure rose slightly with increasing electrosprayed currents. Residual gas analysis revealed that gas component at negative mode was different from that at positive mode. Experimental results indicate that vacuum electrospray of pure ionic liquids is applicable to a massive-cluster beam source for SIMS.

Fujiwara, Yukio; Saito, Naoaki; Nonaka, Hidehiko; Nakanaga, Taisuke; Ichimura, Shingo

2010-06-01

299

Anharmonicity and Fragility of Protic Ionic Liquids  

NASA Astrophysics Data System (ADS)

Supercooled liquids are often characterized by their fragility which is associated with physicochemical properties. However, the origin of fragility is still controversial. Superfragile liquid, decahydroisoquinoline (DHiQ) is chosen as a parent molecule to systematically investigate the relationship between anharmonicity and fragility of supercooled liquids. Earlier study by Ueno et al. (J. Phys. Chem. B 2012, 116) demonstrated that the protonation of DHiQ by different Bronsted acids results in the loss of superfragility. To understand the nature of fragile liquids, we conducted inelastic/quasielastic (IE/QE) neutron scattering measurements to examine low frequency vibrational dynamics (boson peak) and the relaxation behavior of DHiQ (high fragility) and DHiQ-based ionic liquids with intermediate (formate, Fm) and low (trifluoromethansulfonimide, TFSI) fragilities. With the protonation, molecular acids will be hydrogen-deficient and the scattering will be dominated by cation, [DHiQ^+]. This strategy simplifies our interpretation in terms of understanding the fitting result from IENS/QENS spectra. By protonating DHiQ with stronger acids, large shift in low frequency vibrational modes and smaller mean square displacements were examined at temperatures higher than Tg. We illustrate how the degree of protonation and ionicity plays a role in the loss in superfragility of DHiQ.

Kim, Jenny; Angell, Austen; Ueno, Kazuhide; Tyagi, Madhu; Soles, Christopher; Masser, Kevin

2013-03-01

300

A new proton conductive liquid with no ions: pseudo-protic ionic liquids.  

PubMed

Liquids with no ions! Raman analysis and quantum calculations suggest that electrically neutral molecular species predominantly exist in an N-methylimidazole and acetic acid equimolar mixture, and that ionic species are rather minor. Nevertheless, the mixture has significant ionic conductivity, and shows "good ionic" or "superionic" behavior (see figure). It may be suitable to call such liquids "pseudo-ionic liquids" rather than "ionic liquids". PMID:23873834

Doi, Hiroyuki; Song, Xuedan; Minofar, Babak; Kanzaki, Ryo; Takamuku, Toshiyuki; Umebayashi, Yasuhiro

2013-07-19

301

Determination of octopamine, synephrine and tyramine in Citrus herbs by ionic liquid improved 'green' chromatography.  

PubMed

Without adding any volatile organic solvents, aqueous solutions of room temperature ionic liquids (RTILs) were used as 'green' mobile phases to determine octopamine, synephrine and tyramine by liquid chromatography. The problems of the adrenergic amines separation, such as band tailing, low retention and low resolution were solved successfully by using RTIL. The effect of 1-ethyl-3-methylimidazolium tertafluoroborate ([EMIM][BF4]) was the best in the six investigated RTILs. The concentration of [EMIM][BF4], mobile phase pH and column temperature, which influenced the chromatographic behaviors of the analytes, were investigated in detail. The change of retention factors caused by pH shift was obviously suppressed by [EMIM][BF4]. The sensitivity, accuracy and repeatability of this method were found to be satisfactory. The contents of adrenergic amines in several Citrus herbs and extracts, such as Fructus aurantii immaturus, were simultaneously determined by this 'green' chromatographic method. PMID:16781718

Tang, Fei; Tao, Liang; Luo, Xubiao; Ding, Li; Guo, Manli; Nie, Lihua; Yao, Shouzhuo

2006-06-16

302

Ionic liquid based dispersive liquid–liquid microextraction of aromatic amines in water samples  

Microsoft Academic Search

In this work, a new microextraction method termed ionic liquid based dispersive liquid–liquid microextraction (IL-DLLME) was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices. After extraction the ionic liquid (IL) phase was injected directly into the high performance liquid chromatography (HPLC) system for determination. Some parameters that might affect the extraction efficiency were optimized. Under

Yun Chang Fan; Zheng Liang Hu; Mei Lan Chen; Chao Shen Tu; Yan Zhu

2008-01-01

303

Density, speed of sound, and electrical conductance of ionic liquid 1-hexyl-3-methyl-imidazolium bromide in water at different temperatures  

Microsoft Academic Search

Densities, speeds of sound, and electrical conductances in the aqueous solutions of room temperature ionic liquid, 1-hexyl-3-methyl-imidazolium bromide, [HMIm]Br were measured at temperatures T=(283.15 to 308.15)K and atmospheric pressure. Apparent molar volumes V?, isentropic compressibilities ?S, apparent molar isentropic compressibilities ??, and molar conductivities ? were determined. The corresponding limiting apparent molar quantities were found by extrapolation to infinite dilution

Hemayat Shekaari; Yagoub Mansoori; Rahmat Sadeghi

2008-01-01

304

Ionic liquid-based gel polymer electrolyte for LiMn 0.4Fe 0.6PO 4 cathode prepared by electrospinning technique  

Microsoft Academic Search

Two polymer electrolytes (PEs), one consisting of 1M LiPF6 in ethylene carbonate (EC)\\/dimethyl carbonate (DMC) (PEEC\\/DMC) and the other consisting of LiTFSI in room temperature ionic liquid (RTIL), 1-ethyl-3-methyl imidazolium bis(trifluoromethane sulfonyl)imide (EMITFSI) (PEIL), were prepared by using electrospun P(VdF-HFP) membranes. The PEs showed typical impedance spectroscopic responses with high conductivity and good anodic stability. The PEs were applied with

Jae-Kwang Kim; James Manuel; Ghanshyam S. Chauhan; Jou-Hyeon Ahn; Ho-Suk Ryu

2010-01-01

305

Partitioning of butanol and other fermentation broth components in phosphonium and ammonium-based ionic liquids and their toxicity to solventogenic clostridia  

Microsoft Academic Search

For bio-butanol to be competitive with other commercially available fuels like gasoline, the development of energy-efficient technologies for its separation from dilute fermentation broth is necessary. Due to their special properties as extractants, the suitability of selected ammonium and phosphonium cation-based room temperature ionic liquids (RTILs) for butanol separation is investigated in this work. Determination of the RTIL extractants’ partition

Hercules R. Cascon; Santosh K. Choudhari; Grace M. Nisola; Eleazer L. Vivas; Dong-Ju Lee; Wook-Jin Chung

2011-01-01

306

Thermodynamic Phase Behavior of Tosylate Ionic Liquids and Sulphur Extraction  

Microsoft Academic Search

Isothermal vapor-liquid equilibrium data, (VLE) have been measured by an ebulliometric method for three binary mixtures containing ionic liquid (IL) 1-butyl-4-methylpyridinium tosylate (BMPy)(TOS) with alcohols (ethanol, propan-1-ol, butan-1-ol) at T = 373.15 K. The experimental VLE results have been correlated using Wilson equation. Solid-liquid equilibria (SLE) and liquid-liquid equilibria (LLE) of binary systems containing ionic liquid 1-butyl-3-methylimidazolium tosylate (BMIM)(TOS) with:

Marek Królikowski

307

Pressure effect on vibrational frequency and dephasing of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids.  

PubMed

Raman spectra in the range of the totally symmetric stretching mode of the [PF6](-) anion, ?s(PF6), have been measured for 1-alkyl-3-methylimidazolium ionic liquids [CnC1im][PF6], for n = 4, 6, and 8, as a function of pressure at room temperature. The ionic liquids [C6C1im][PF6] and [C8C1im][PF6] remain in an amorphous phase up to 3.5 GPa, in contrast to [C4C1im][PF6], which crystallizes above ~0.5 GPa. Equations of state based either on a group contribution model or Carnahan-Starling-van der Waals model have been used to estimate the densities of the ionic liquids at high pressures. The shifts of the vibrational frequency of ?s(PF6) with density observed in [C6C1im][PF6] and in [C8C1im][PF6] have been calculated by a hard-sphere model of a pseudo-diatomic solute under short-range repulsive interactions with the neighboring particles. The stochastic model of Kubo for vibrational dephasing has been used to obtain the amplitude of vibrational frequency fluctuation, , and the relaxation time of frequency fluctuation, ?c, as a function of density by Raman band shape analysis of the ?s(PF6) mode of [C6C1im][PF6] and [C8C1im][PF6]. PMID:23927273

Pison, L; Costa Gomes, M F; Pádua, A A H; Andrault, D; Norman, S; Hardacre, C; Ribeiro, M C C

2013-08-01

308

Microheterogeneity of some imidazolium ionic liquids as revealed by fluorescence correlation spectroscopy and lifetime studies.  

PubMed

The microscopic structure and dynamics of the room temperature ionic liquids (RTILs) that are responsible for some of the peculiar properties of this class of solvents continue to intrigue the researchers and stimulate new investigations. Herein, we use the fluorescence correlation spectroscopy (FCS) technique to study the diffusion of some probe molecules in RTILs, the results of which, when combined with those obtained from fluorescence lifetime studies, provide insights into the microscopic structural details of this class of novel solvents. Experiments performed with three charged and neutral probe molecules in five carefully selected 1-alkyl-3-methylimidazolium ionic liquids reveal that unlike in conventional solvents these probes exhibit a bimodal diffusion behavior in RTILs thus indicating the presence of two distinct environments. It is found that the contribution of the slow component of the diffusion increases with increasing alkyl chain length of the cation. Not only are these results supported by the biexponential decay behavior of the fluorescence intensity of the systems, but the individual values of the lifetime components and their weight allow determination of the nature of the two major environments. In essence, the results point to the potential of the two combined techniques in unraveling some of the complex features of the ionic liquids. PMID:23030623

Patra, Satyajit; Samanta, Anunay

2012-10-02

309

Electrocatalytic oxidation of dopamine at an ionic liquid modified carbon paste electrode and its analytical application.  

PubMed

A room-temperature ionic liquid N-butylpyridinium hexafluorophosphate was used as a binder to construct an ionic liquid modified carbon paste electrode, which was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The ionic liquid carbon paste electrode (IL-CPE) showed enhanced electrochemical response and strong analytical activity towards the electrochemical oxidation of dopamine (DA). A pair of well-defined quasireversible redox peaks of DA appeared, with the redox peaks located at 215 mV (E (pa)) and 151 mV (E (pc)) (vs. the saturated calomel electrode, SCE) in pH 6.0 phosphate buffer solution. The formal potential (E (0')) was calculated as 183 mV (vs. SCE) and the peak-to-peak separation as 64 mV. The electrochemical behavior of DA on the IL-CPE was carefully investigated. Under the optimal conditions, the anodic peak currents increased linearly with the concentration of DA in the range 1.0 x 10(-6)-8.0 x 10(-4) mol/L and the detection limit was calculated as 7.0 x 10(-7) mol/L (3sigma). The interferences of foreign substances were investigated and the proposed method was successfully applied to the determination of DA injection samples. The IL-CPE fabricated was sensitive, selective and showed good ability to distinguish the coexisting ascorbic acid and uric acid. PMID:17701400

Sun, Wei; Yang, Maoxia; Jiao, Kui

2007-08-16

310

Pressure effect on vibrational frequency and dephasing of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids  

NASA Astrophysics Data System (ADS)

Raman spectra in the range of the totally symmetric stretching mode of the [PF6]- anion, ?s(PF6), have been measured for 1-alkyl-3-methylimidazolium ionic liquids [CnC1im][PF6], for n = 4, 6, and 8, as a function of pressure at room temperature. The ionic liquids [C6C1im][PF6] and [C8C1im][PF6] remain in an amorphous phase up to 3.5 GPa, in contrast to [C4C1im][PF6], which crystallizes above ~0.5 GPa. Equations of state based either on a group contribution model or Carnahan-Starling-van der Waals model have been used to estimate the densities of the ionic liquids at high pressures. The shifts of the vibrational frequency of ?s(PF6) with density observed in [C6C1im][PF6] and in [C8C1im][PF6] have been calculated by a hard-sphere model of a pseudo-diatomic solute under short-range repulsive interactions with the neighboring particles. The stochastic model of Kubo for vibrational dephasing has been used to obtain the amplitude of vibrational frequency fluctuation, , and the relaxation time of frequency fluctuation, ?c, as a function of density by Raman band shape analysis of the ?s(PF6) mode of [C6C1im][PF6] and [C8C1im][PF6].

Pison, L.; Costa Gomes, M. F.; Pádua, A. A. H.; Andrault, D.; Norman, S.; Hardacre, C.; Ribeiro, M. C. C.

2013-08-01

311

Ionic liquid high-temperature gas sensor array.  

PubMed

A novel sensor array using seven room-temperature ionic liquids (ILs) as sensing materials and a quartz crystal microbalance (QCM) as a transducer was developed for the detection of organic vapors at ambient and elevated temperatures. Ethanol, dichloromethane, benzene, and heptane were selected as representative gas analytes for various kinds of environmental pollutants and common industrial solvents. The QCM/IL sensors responded proportionately and reversibly to the organic vapor concentrations (i.e., ethanol, heptane, and benzene) in the gas phase from 0 to 100% saturation at room and elevated temperatures (e.g., 120 degrees C) but deviated from this linear relationship at high concentrations for dichloromethane, a highly volatile compound. Linear discriminant analysis was used to analyze the sensing patterns. Excellent classifications were obtained for both known and unknown concentrations of vapor samples. The correct classifications were 100% for known concentration samples and 96% for samples with unknown concentrations. Thermodynamics and ATR-FT-IR studies were conducted to understand specific molecular interactions, the strength of the interaction between ILs and organic vapors, and the degree of ordering that takes place upon dissolution of the vapors in ILs. The different response intensity of the QCM/IL sensors to the organic vapors depends on the different solubilities of organic vapors in ILs and varying molecular/ion interactions between each organic vapor and IL. The diverse set of IL studied showed selective responses due to structural differences. Therefore, a sensor array of ILs would be able to effectively differentiate different vapors in pattern recognitions, facilitating discrimination by their distinctive patterns in response to organic vapors in both room and high temperatures. PMID:17007524

Jin, Xiaoxia; Yu, Lei; Garcia, Diego; Ren, Rex X; Zeng, Xiangqun

2006-10-01

312

On the radiation stability of crown ethers in ionic liquids.  

SciTech Connect

Crown ethers (CEs) are macrocyclic ionophores used for the separation of strontium-90 from acidic nuclear waste streams. Room temperature ionic liquids (ILs) are presently being considered as replacements for traditional molecular solvents employed in such separations. It is desirable that the extraction efficacy obtained with such solvents should not deteriorate in the strong radiation fields generated by decaying radionuclides. This deterioration will depend on the extent of radiation damage to both the IL solvent and the CE solute. While radiation damage to ILs has been extensively studied, the issue of the radiation stability of crown ethers, particularly in an IL matrix, has not been adequately addressed. With this in mind, we have employed electron paramagnetic resonance (EPR) spectroscopy to study the formation of CE-related radicals in the radiolysis of selected CEs in ILs incorporating aromatic (imidazolium and pyridinium) cations. The crown ethers have been found to yield primarily hydrogen loss radicals, H atoms, and the formyl radical. In the low-dose regime, the relative yield of these radicals increases linearly with the mole fraction of the solute, suggesting negligible transfer of the excitation energy from the solvent to the solute; that is, the solvent has a 'radioprotective' effect. The damage to the CE in the loading region of practical interest is relatively low. Under such conditions, the main chemical pathway leading to decreased extraction performance is protonation of the macrocycle. At high radiation doses, sufficient to increase the acidity of the IL solvent significantly, such proton complexes compete with the solvent cations as electron traps. In this regime, the CEs will rapidly degrade as the result of H abstraction from the CE ring by the released H atoms. Thus, the radiation dose to which a CE/IL system is exposed must be maintained at a level sufficiently low to avoid this regime.

Shkrob, I.; Marin, T.; Dietz, M. (Chemical Sciences and Engineering Division); (Benedictine Univ.); (Univ. of Wisconsin at Milwaukee)

2011-04-14

313

Application of ionic liquid in liquid phase microextraction technology.  

PubMed

Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction. PMID:23002004

Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

2012-09-24

314

Ferroelectric phase transitions near ionic liquid/vacuum interfaces.  

PubMed

A simple theoretical model is developed describing ionic liquids as regular solutions. The separation of these ionic mixtures is studied on the base of the Cahn-Hilliard theory coupled with electrostatics. It is shown that the ionic liquids decompose to thin layers of oppositely charged liquids at low temperatures. At larger temperatures the separation occurs only near the ionic liquid/vacuum surface, thus explaining the oscillatory-decaying structure of the electric double layer observed via computer simulations. In contrast to noncharged liquids the ionic ones exhibit two critical temperatures, where the temperature coefficients of all characteristic lengths possess singularities. These second order ferroelectric phase transitions are possible explanations of the experimentally measured via light scattering peculiar temperature dependence of the interfacial dipole moment density on several ionic liquid/vacuum interfaces. PMID:17523790

Tsekov, Roumen

2007-05-21

315

Ionic liquids are compatible with on-water catalysis.  

PubMed

A major limitation of on-water catalysis has been the need for liquid reactants to enable emulsification. We demonstrate that ionic liquids are compatible with on-water catalysis, enabling on-water catalysed reactions for otherwise unreactive solid-solid systems. The unique solvation properties of ionic liquids dramatically expands the scope of on-water catalysis. PMID:23929275

Beare, Kaitlin D; Yuen, Alexander K L; Masters, Anthony F; Maschmeyer, Thomas; McErlean, Christopher S P

2013-08-22

316

Periodicity and map for discovery of new ionic liquids  

Microsoft Academic Search

There is virtually no limit in the number of ionic liquids. How to select proper ones or discover new ones with desirable\\u000a properties in such a large pool of ionic liquids? It has become a bottleneck in the researches and applications of ionic liquids.\\u000a Mendeleev’s periodic law states that the properties of the elements vary periodically. Whether the similar regularity

Suojiang Zhang; Ning Sun; Xiangping Zhang; Xingmei Lü

2006-01-01

317

High vacuum distillation of ionic liquids and separation of ionic liquid mixtures.  

PubMed

The vaporisation of ionic liquids has been investigated using temperature programmed desorption (TPD) and ultra-high vacuum (UHV) distillation. 1-Alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids, [C(n)C(1)Im][Tf(2)N] (n = 2, 8), have been distilled at UHV and T > 500 K in a specially designed still. The distillation process yielded spectroscopically pure ionic liquid distillates with complete removal of volatile impurities such as water, argon and 1-methylimidazole. Such UHV distillation offers a method of obtaining high purity ionic liquids for analytical applications. The vapour phase of the ionic liquid mixtures [C(2)C(1)Im](0.05)[C(8)C(1)Im](0.95)[Tf(2)N] and [C(2)C(1)Im][C(8)C(1)Im][Tf(2)N][EtSO(4)] has been analysed by TPD using line-of-sight mass spectrometry (LOSMS). The vapour phase consisted of all possible combinations of neutral ion pairs (NIPs) from the liquid mixture. Neither mixture showed evidence of decomposition during TPD, and the [C(2)C(1)Im](0.05)[C(8)C(1)Im](0.95)[Tf(2)N] mixture was shown to obey Raoult's law. Based on the TPD results, fractional distillations were attempted for [C(2)C(1)Im][C(8)C(1)Im][Tf(2)N](2) and [C(2)C(1)Im][C(8)C(1)Im][Tf(2)N][EtSO(4)] mixtures. The distillate from [C(2)C(1)Im][C(8)C(1)Im][Tf(2)N](2) was enhanced in the more volatile [C(2)C(1)Im][Tf(2)N] components, but the [C(2)C(1)Im][C(8)C(1)Im][Tf(2)N][EtSO(4)] mixture underwent significant decomposition. The similarities and differences between UHV TPD, and high vacuum distillation, of ionic liquids, are discussed. Design parameters are outlined for a high vacuum ionic liquid still that will minimise decomposition and maximise separation of ILs of differing volatility. PMID:20145842

Taylor, Alasdair W; Lovelock, Kevin R J; Deyko, Alexey; Licence, Peter; Jones, Robert G

2010-01-06

318

Enzymatic polyester synthesis in ionic liquids  

Microsoft Academic Search

The enzymatic synthesis of polyesters by ring-opening polymerization (ROP) and polycondensation in three ionic liquids, i.e., [bmim][Tf2N], [bmim][PF6] and [bmim][BF4] was investigated. For the enzymatic ROP of ?-caprolactone it was found that [bmim][PF6] and [bmim][BF4] result in an inhomogeneous reaction mixture upon polymerization, causing polymerization characteristics similar to bulk polymerization. In contrast, for [bmim][Tf2N] characteristics similar to toluene were observed.

Rebeca Marcilla; Matthijs de Geus; David Mecerreyes; Christopher J. Duxbury; Cor E. Koning; Andreas Heise

2006-01-01

319

Nonlinear capacitance and electrochemical behavior of ionic liquid-ionic polymer transducers  

NASA Astrophysics Data System (ADS)

Ionic polymer transducers (IPTs) are soft sensors and actuators which operate through a coupling of micro-scale chemical, electrical, and mechanical interactions. The use of an ionic liquid as solvent for an IPT has been shown to dramatically increase transducer lifetime in free-air use, while also allowing for higher applied voltages without electrolysis. In this work we model charge transport in an ionic liquid IPT by considering both the cation and anion of the ionic liquid as mobile charge carriers, a phenomenon which is unique to ionic liquid IPTs compared to their water-based counterparts. The electrochemical behavior of the large ionic liquid ions is described through a modification of the Nernst-Planck equation given by Kornyshev which accounts for steric effects in double layer packing. The method of matched asymptotic expansions is applied to solve the resulting system of equations, and analytical expressions are derived for the nonlinear charge transferred and capacitance of the IPT as a function of the applied voltage. The influence of the fraction of mobile ionic liquid ions and steric effects on the capacitance of an ionic liquid IPT is shown and compared to water-based IPTs. These results show the fundamental charge transport differences between water-based and ionic liquid IPTs and give considerations for future transducer development.

Davidson, Jacob D.; Goulbourne, N. C.

2010-03-01

320

Cloud point phenomena for POE-type nonionic surfactants in imidazolium-based ionic liquids: effect of anion species of ionic liquids on the cloud point.  

PubMed

Cloud point temperatures, T(c), of polyoxyethylene (POE)-type nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF(6)), were measured and compared with those previously obtained for the surfactant solution in bmimBF(4). The T(c)s for bmimPF(6) solution are higher than those for bmimBF(4) solution by approx. 40 degrees C. This means that the surfactant molecules are more solvophilic in bmimPF(6) compared to bmimBF(4). The analysis of (1)H NMR chemical shift measurements proved that the higher solvophilicity of the surfactants in bmimPF(6) is attributed to weaker hydrogen-bond interaction between bmim cation and PF6- anion than that between bmim cation and BF4- anion. This interpretation is consistent with the interaction energy parameters derived from the thermodynamic analysis of cloud point curve applying the Flory-Huggins model for phase separation in polymer solution. The present work demonstrates that the property of imidazolium-based ionic liquids as a solvent is determined by a balance of interactions among imidazolium cation, counter anion, and solute molecule. PMID:19486995

Inoue, Tohru; Misono, Takeshi

2009-05-12

321

Tribological evaluation of ?, ? ´ -diimidazoliumalkylene hexafluorophosphate ionic liquid and benzotriazole as additive  

Microsoft Academic Search

Ionic liquids of ?, ?´-diimidazoliumalkylene hexafluorophosphate were synthesized. The tribological properties of the synthetic ionic liquid and the ionic liquid contained additive for contacts of steel\\/steel were investigated by Optimol SRV oscillating friction and wear tester under ambient conditions. The synthetic ionic liquid presented low friction coefficients and small wear volumes, especially under higher temperatures. The ionic liquid doped with

Bo Yu; Feng Zhou; Chongjun Pang; Bo Wang; Yongmin Liang; Weimin Liu

2008-01-01

322

Extraction of proteins with ionic liquid aqueous two-phase system based on guanidine ionic liquid.  

PubMed

Eight kinds of green ionic liquids were synthesized, and an ionic liquid aqueous two-phase system (ILATPS) based on 1,1,3,3-tetramethylguandine acrylate (TMGA) guanidine ionic liquid was first time studied for the extraction of proteins. Single factor experiments proved that the extraction efficiency of bovine serum albumin (BSA) was influenced by the mass of IL, K2HPO4 and BSA, also related to the separation time and temperature. The optimum conditions were determined through orthogonal experiment by the five factors described above. The results showed that under the optimum conditions, the extraction efficiency could reach up to 99.6243%. The relative standard deviations (RSD) of extraction efficiencies in precision experiment, repeatability experiment and stability experiment were 0.8156% (n=5), 1.6173% (n=5) and 1.6292% (n=5), respectively. UV-vis and FT-IR spectra confirmed that there were no chemical interactions between BSA and ionic liquid in the extraction process, and the conformation of the protein was not changed after extraction. The conductivity, DLS and TEM were combined to investigate the microstructure of the top phase and the possible mechanism for the extraction. The results showed that hydrophobic interaction, hydrogen bonding interaction and the salt out effect played important roles in the transferring process, and the aggregation and embrace phenomenon was the main driving force for the separation. All these results proved that guanidine ionic liquid-based ATPSs have the potential to offer new possibility in the extraction of proteins. PMID:24148423

Zeng, Qun; Wang, Yuzhi; Li, Na; Huang, Xiu; Ding, Xueqin; Lin, Xiao; Huang, Songyun; Liu, Xiaojie

2013-06-17

323

Trimethylsilylation of cellulose in ionic liquids.  

PubMed

Trimethylsilylation of cellulose in different 1,3-dialkylimidazolium ionic liquids (IL) with hexamethyldisilazane (HMDS) as a silylating agent was investigated. Trimethylsilyl (TMSi) cellulose with a degree of substitution (DS) greater than 1 is insoluble in the IL. The maximum DS obtained depends on the nature of the anion. Carboxylate and diethylphosphate counterions gave better results than chloride or thiocyanate, which corresponds to the solubility of HMDS in the IL. Controlled silylation with stoichiometric amounts of HMDS was feasible in imidazolium carboxylates and diethylphosphate. Analysis of the substitution pattern of the silyl groups in the anhydroglucose unit (AGU) by methylation analysis gave a more homogeneous distribution under (initially) homogeneous conditions (fewer unsubstituted AGUs, fewer trisubstituted AGUs) compared to TMSi cellulose obtained in liquid ammonia. PMID:19031387

Mormann, Werner; Wezstein, Markus

2009-04-01

324

On the dynamic response of externally wetted ionic liquid ion sources  

NASA Astrophysics Data System (ADS)

The electrostatic extraction of nearly monochromatic solvated ions from externally wetted emitters is possible in the case of some ionic liquids or room temperature molten salts. These compact devices are similar to liquid metal ion sources but positive or negative ion beams can be obtained simply by selecting the appropriate polarity for the power supply. dc operation on a single polarity over relatively long periods of time induces electrochemical degradation of the liquid-metal system making voltage alternation at frequencies of the order of 1 Hz necessary to sustain chemical neutrality. This periodic interruption forces a non-steady state behaviour. In particular, the ion current onset is delayed from a square-shaped voltage input signal by a few milliseconds for tungsten metal emitters wetted with the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate, setting the upper bound for the alternation frequency at about 75 Hz. The dependences of these delays on absolute applied voltages are experimentally explored for this compound, suggesting that viscous drag is the main factor determining the dynamic response.

Lozano, Paulo; Martínez-Sánchez, Manuel

2005-07-01

325

Structural and electrochemical properties of succinonitrile-based gel polymer electrolytes: role of ionic liquid addition.  

PubMed

Experimental studies on the novel compositions of gel polymer electrolytes, comprised of plastic crystal succinonitrile (SN) dispersed with pyrrolidinium and imidazolium-based ionic liquids (ILs) entrapped in a host polymer poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), are reported. The gel electrolytes are in the form of free-standing films with excellent mechanical, thermal, and electrochemical stability. The introduction of even a small content (~1 wt %) of ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)imide (BMPTFSI) or 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) in the PVdF-HFP/SN system (1:4 w/w) enhances the electrical conductivity by 4 orders of magnitude, that is, from ~10(-7) to ~10(-3) S cm(-1) at room temperature. The structural changes due to the entrapment of SN or SN/ILs mixtures and ion-SN-polymer interactions are examined by Fourier transform infrared (FTIR)/Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimmetry (DSC). Various physicochemical properties and fast ion conduction in the gel polymer membranes show their promising characteristics as electrolytes in different ionic devices including supercapacitors. PMID:23758408

Suleman, Mohd; Kumar, Yogesh; Hashmi, S A

2013-06-11

326

Temperature-dependent structure of ionic liquids: X-ray scattering and simulations  

SciTech Connect

In this article we determine the temperature-dependent structure of the tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl)amide ionic liquid using a combination of X-ray scattering and molecular dynamics simulations. As in many other room-temperature ionic liquids three characteristic intermolecular peaks can be detected in the structure function S(q). A prepeak or first sharp diffraction peak is observed at about q = 0.42 {angstrom}{sup -1}. Long range anion-anion correlations are the most important contributors to this peak. In all systems we have studied to date, this prepeak is a signature of solvation asymmetry. The peak in S(q) near q = 0.75 {angstrom}{sup -1} is the signature of ionic alternation and arises from the charge ordered separation of ions of the same charge. The most intense diffraction peak near q = 1.37 {angstrom}{sup -1} arises from short-range separation between ions of opposite charge combined with a significant contribution from cationic carbon-carbon interactions, indicating that cationic hydrophobic tails have significant contacts.

Kashyap, Hemant K.; Santos, Cherry S.; Annapureddy, Harsha V.R.; Murthy, N. Sanjeeva; Margulis, Claudio J.; Castner, Jr., Edward W. (SUNJ)

2012-03-15

327

Novel synthesis of methoxymethyl benzene by electrochemical coupling reaction of toluene with methanol in ionic liquid media.  

PubMed

An ionic liquid (1-butyl-3-methylimidazolium dibutyl phosphate) was prepared and characterized by cyclic voltammogram (CV) and Fourier transform infrared spectrometer (FT-IR). The ionic liquid exhibited good catalytic activity for the electrochemical reaction of toluene with methanol assisted with a pair of porous graphite plane electrodes and product yield higher than 56% was observed. In addition, the electrochemical process was detected by UV-vis spectrum and the products were analyzed by gas chromatography/mass spectrometry (GC/MS). According to the experimental results, a possible free radical reaction mechanism was proposed. It may be concluded that a simply and feasible electrochemical coupling reaction at room temperature and atmospheric pressure may be possible. Compared with methyl tert-butyl ether (MTBE), the main product (methoxymethyl benzene) used as booster to improve fuel combustion was also studied. PMID:19056178

Chen, Fengtao; Wang, Bo; Ma, Hongzhu

2008-10-28

328

Ionic liquids from copper(II) complexes with alkylimidazole-containing tripodal ligands.  

PubMed

Five-coordinate copper(II) complexes [Cu(L)Cl]X bearing alkylimidazole-containing tripodal ligands were prepared, where L = bis(2-dimethylaminoethyl)-((1-alkylimidazol-2-yl)methyl)amine and X = bis(trifluoromethanesulfonyl)amide (Tf2N) and PF6. The salts with hexyl ([1]X), propyl ([2]X), and methyl ([3]X) substituents in the ligand were prepared, of which [1]Tf2N and [2]Tf2N were ionic liquids with high viscosity at room temperature. X-ray crystal structure determination at low temperature revealed that the coordination geometry around the metal ion in [3]Tf2N was distorted trigonal bipyramidal, whereas that in [2]PF6 was close to square pyramidal. UV-vis absorption spectra of these salts were consistent with the coordination structures. PMID:23719677

Funasako, Yusuke; Nosho, Misaki; Mochida, Tomoyuki

2013-07-28

329

New force field for molecular simulation of guanidinium-based ionic liquids.  

PubMed

An all-atom force field was proposed for a new class of room temperature ionic liquids (RTILs), N,N,N',N'-tetramethylguanidinium (TMG) RTILs. The model is based on the AMBER force field with modifications on several parameters. The refinements include (1) fitting the vibration frequencies for obtaining force coefficients of bonds and angles against the data obtained by ab initio calculations and/or by experiments and (2) fitting the torsion energy profiles of dihedral angles for obtaining torsion parameters against the data obtained by ab initio calculations. To validate the force field, molecular dynamics (MD) simulations at different temperatures were performed for five kinds of RTILs, where TMG acts as a cation and formate, lactate, perchlorate, trifluoroacetate, and trifluoromethylsulfonate act as anions. The predicted densities were in good agreement with the experimental data. Radial distribution functions (RDFs) and spatial distribution functions (SDFs) were investigated to depict the microscopic structures of the RTILs. PMID:16800517

Liu, Xiaomin; Zhang, Suojiang; Zhou, Guohui; Wu, Guangwen; Yuan, Xiaoliang; Yao, Xiaoqian

2006-06-22

330

Tetraalkylphosphonium polyoxometalates: electroactive, "task-specific" ionic liquids.  

PubMed

The pairing of selected polyoxometalate (POM) anions with appropriate tetraalkylphosphonium cations is shown to yield an original family of ionic liquids, among them an ambient-temperature "liquid POM". PMID:17225903

Rickert, Paul G; Antonio, Mark R; Firestone, Millicent A; Kubatko, Karrie-Ann; Szreder, Tomasz; Wishart, James F; Dietz, Mark L

2006-12-21

331

Tetraalkylphosphonium polyoxometalates : Electroactive, 'task-specific' ionic liquids.  

SciTech Connect

The pairing of selected polyoxometalate (POM) anions with appropriate tetraalkylphosphonium cations is shown to yield an original family of ionic liquids, among them an ambient-temperature 'liquid POM.'

Rickert, P. G.; Antonio, M. R.; Firestone, M. A.; Kubatko, K-A.; Szreder, T.; Wishart, J. F.; Dietz, M. L.; BNL; Univ. of Miami

2007-01-01

332

Formation of F Centers at Low and Room Temperatures  

Microsoft Academic Search

It has been found that the x-ray production of F centers at liquid helium temperature is primarily dependent on the type of alkali halide and not on the defect structure of the particular specimen in contrast to observations at room temperature. This result indicates that the low-temperature production of F centers is a bulk property of the alkali halide and

Herbert Rabin; Clifford C. Klick

1960-01-01

333

Phase equilibria study of the binary systems (N-hexylisoquinolinium thiocyanate ionic liquid + organic solvent or water).  

PubMed

Liquid-liquid phase equilibria (LLE) of binary mixtures containing a room-temperature ionic liquid N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] with an aliphatic hydrocarbon (n-hexane, n-heptane), aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), cyclohexane, thiophene, water, and 1-alcohol (1-ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol) have been determined using a dynamic method from room temperature to the boiling-point of the solvent at ambient pressure. N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] has been synthesized from N-hexyl-isoquinolinium bromide as a substrate. Specific basic characterization of the new compound including NMR spectra, elementary analysis, and water content have been done. The density and viscosity of pure ionic liquid were determined over a wide temperature range from 298.15 to 348.15 K. The mutual immiscibility with an upper critical solution temperature (UCST) for the binary systems {IL + aliphatic hydrocarbon, cyclohexane, or water} was detected. In the systems of {IL + aromatic hydrocarbon or thiophene} an immiscibility gap with a lower critical solution temperature (LCST) was observed. Complete miscibility in the liquid phase, over a whole range of ionic liquid mole fraction, was observed for the binary mixtures containing IL and an 1-alcohol. For the tested binary systems with immiscibility gap {IL + aliphatic hydrocarbon, aromatic hydrocarbon, cyclohexane, thiophene, or water}, the parameters of the LLE correlation have been derived using the NRTL equation. The basic thermal properties of the pure IL, that is, the glass-transition temperature as well as the heat capacity at the glass-transition temperature, have been measured using a differential scanning microcalorimetry technique (DSC). Decomposition of the IL was detected by simultaneous thermogravimetric/differential thermal analysis (TG/DTA) experiments. PMID:22424076

Królikowska, Marta; Karpi?ska, Monika; Zawadzki, Maciej

2012-03-29

334

Examination of the Potential of Ionic Liquids for Gas Separations  

Microsoft Academic Search

Ionic liquids have received increasing interest in recent years for “green” synthesis and separations because they have essentially no vapor pressure. We have begun an investigation of the potential of ionic liquids for gas separations, including the removal of carbon dioxide from stack gas generated in coal?fired power plants. In this paper, we report results from measurements of the permeance

Ruth E. Baltus; Robert M. Counce; Benjamin H. Culbertson; Huimin Luo; David W. DePaoli; Sheng Dai; Douglas C. Duckworth

2005-01-01

335

Brownian dynamics determine universality of charge transport in ionic liquids  

SciTech Connect

Broadband dielectric spectroscopy is employed to investigate charge transport in a variety of glass-forming ionic liquids over wide frequency, temperature and pressure ranges. Using a combination of Einstein, Einstein-Smoluchowski, and Langevin relations, the observed universal scaling of charge transport in ionic liquids is traced back to the dominant role of Brownian dynamics.

Sangoro, Joshua R [ORNL; Iacob, Ciprian [University of Leipzig; Mierzwa, Michal [University of Silesia, Uniwersytecka, Katowice, Poland; Paluch, Marian [University of Silesia, Uniwersytecka, Katowice, Poland; Kremer, Friedrich [University of Leipzig

2012-01-01

336

Ionic Liquids and Green Chemistry: A Lab Experiment  

ERIC Educational Resources Information Center

|Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of…

Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

2010-01-01

337

Combined reactions and separations using ionic liquids and carbon dioxide  

Microsoft Academic Search

A new and general type of process for the chemical industry is presented using ionic liquids and supercritical carbon dioxide as combined reaction and separation media. In this process, the carbon dioxide pressure controls the miscibility of reactants, products, catalyst and ionic liquid, enabling fast atom-efficient reactions in a homogenous phase as well as instantaneous product recovery in a biphasic

M. C. Kroon

2006-01-01

338

Ionic Liquids and Green Chemistry: A Lab Experiment  

ERIC Educational Resources Information Center

Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of…

Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

2010-01-01

339

Enantioselective chemo- and bio-catalysis in ionic liquids  

Microsoft Academic Search

Recent developments in the enantioselective chemo- and bio- catalysis in ionic liquids are reviewed. In many cases, the use of ionic liquids provides many advantages over reactions in conventional organic solvents in terms of activity, enantiose- lectivity, stability and the reusability of the solvent-catalyst systems.

Choong Eui Song

2004-01-01

340

The simulation of imidazolium-based ionic liquids  

Microsoft Academic Search

In the absence of reliable experimental data, significant difficulties have been encountered in the design of force fields for the simulation of imidazolium-based ionic liquids. This review examines the problems encountered and improvements made in developing force fields for the study of imidazolium-based ionic liquids. The performance of these models is assessed with respect to the prediction of structural and

P. A. Hunt

2006-01-01

341

Reaction of pharmacological active tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate with ZnCl2 or NiCl2: first conversion of a protic ionic liquid into metallated ionic liquid  

PubMed Central

The reaction of pharmacological active protic ionic liquid tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate H+N(CH2CH2OH)3 ? (-OOCCH2SC6H4Cl-4) (1) with zinc or nickel chloride in a ratio of 2:1 affords stable at room temperature powder-like adducts [H+N(CH2CH2OH)3]2 ? [M(OOCCH2SC6H4Cl-4)2Cl2]2-, M = Zn (2), Ni (3). By recrystallization from aqueous alcohol compound 2 unexpectedly gives Zn(OOCCH2SC6H4Cl-4)2 ? 2H2O (4). Unlike 2, compound 3 gives crystals [N(CH2CH2OH)3]2Ni2+?·?[-OOCCH2SC6H4Cl-4]2 (5), which have a structure of metallated ionic liquid. The structure of 5 has been proved by X-ray diffraction analysis. It is the first example of the conversion of a protic ionic liquid into potentially biological active metallated ionic liquid (1???3???5).

2013-01-01

342

Fluorescence and Circular Dichroism Spectroscopy of Cytochrome c in Alkylammonium Formate Ionic Liquids  

PubMed Central

The structural stability of cytochrome c has been studied in alkylammonium formate (AAF) ionic liquids such as methylammonium formate (MAF) and ethylammonium formate (EAF) by fluorescence and circular dichroism (CD) spectroscopy. At room temperature, the native structure of cytochrome c is maintained in relatively high ionic liquid concentrations (50%–70% AAF/water or AAF/phosphate buffer pH 7.0) in contrast to denaturation of cytochrome c in similar solutions of methanol or acetonitrile, with water or buffer co-solvents. Fluorescence and CD spectra indicate the conformation of cytochrome c is maintained in 20% AAF-80% water from 30 – 50 °C. No such temperature stability is found in 80% AAF-20% water. About one third of the enzyme activity of cytochrome c in 80% AAF-20% water can be maintained as compared to phosphate buffer and this is greater than the activities measured in corresponding methanol and acetonitrile aqueous solutions. This biophysical study shows that AAFs have potential application as organic solvent replacements at moderate temperature in the mobile phase for the separation of proteins in their native form by reversed phase liquid chromatography.

Wei, Wenjun; Danielson, Neil D.

2012-01-01

343

Intermolecular vibrations and fast relaxations in supercooled ionic liquids  

NASA Astrophysics Data System (ADS)

Short-time dynamics of ionic liquids has been investigated by low-frequency Raman spectroscopy (4 < ? < 100 cm-1) within the supercooled liquid range. Raman spectra are reported for ionic liquids with the same anion, bis(trifluoromethylsulfonyl)imide, and different cations: 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-1-methylpiperidinium, trimethylbutylammonium, and tributylmethylammonium. It is shown that low-frequency Raman spectroscopy provides similar results as optical Kerr effect (OKE) spectroscopy, which has been used to study intermolecular vibrations in ionic liquids. The comparison of ionic liquids containing aromatic and non-aromatic cations identifies the characteristic feature in Raman spectra usually assigned to librational motion of the imidazolium ring. The strength of the fast relaxations (quasi-elastic scattering, QES) and the intermolecular vibrational contribution (boson peak) of ionic liquids with non-aromatic cations are significantly lower than imidazolium ionic liquids. A correlation length assigned to the boson peak vibrations was estimated from the frequency of the maximum of the boson peak and experimental data of sound velocity. The correlation length related to the boson peak (~19 A?) does not change with the length of the alkyl chain in imidazolium cations, in contrast to the position of the first-sharp diffraction peak observed in neutron and X-ray scattering measurements of ionic liquids. The rate of change of the QES intensity in the supercooled liquid range is compared with data of excess entropy, free volume, and mean-squared displacement recently reported for ionic liquids. The temperature dependence of the QES intensity in ionic liquids illustrates relationships between short-time dynamics and long-time structural relaxation that have been proposed for glass-forming liquids.

Ribeiro, Mauro C. C.

2011-06-01

344

Bioanalytical separation and preconcentration using ionic liquids.  

PubMed

Ionic liquids (ILs) are novel solvents that display a number of unique properties, such as negligible vapor pressure, thermal stability (even at high temperatures), favorable viscosity, and miscibility with water and organic solvents. These properties make them attractive alternatives to environmentally unfriendly solvents that produce volatile organic compounds. In this article, a critical review of state-of-the-art developments in the use of ILs for the separation and preconcentration of bioanalytes in biological samples is presented. Special attention is paid to the determination of various organic and inorganic analytes-including contaminants (e.g., pesticides, nicotine, opioids, gold, arsenic, lead, etc.) and functional biomolecules (e.g., testosterone, vitamin B12, hemoglobin)-in urine, blood, saliva, hair, and nail samples. A brief introduction to modern microextraction techniques based on ILs, such as dispersive liquid-liquid microextraction (DLLME) and single-drop microextraction (SDME), is provided. A comparison of IL-based methods in terms of their limits of detection and environmental compatibilities is also made. Finally, critical issues and challenges that have arisen from the use of ILs in separation and preconcentration techniques are also discussed. PMID:23681199

Escudero, Leticia B; Castro Grijalba, Alexander; Martinis, Estefanía M; Wuilloud, Rodolfo G

2013-05-17

345

Conversion of cellulose to HMF in ionic liquid catalyzed by bifunctional ionic liquids.  

PubMed

A new kind of bifunctional ionic liquid catalysts was synthesized to degrade microcrystalline cellulose in [BMIM]Cl at atmospheric pressure. The effects of reaction temperature, amount of catalysts, reaction time, ionic liquid purity and cellulose concentration on conversion were investigated. At low temperature cellulose can be degraded with being heated in [BMIM]Cl by oil bath. Among the as-synthesized catalysts, Cr([PSMIM]HSO4)3 exhibited the best performance. The HMF yield of 53% and TRS yield of 94% can be achieved at 120 °C in [BMIM]Cl for 5 h over 0.05 g Cr([PSMIM]HSO4)3/2.0 g [BMIM]Cl with 95% cellulose conversion. PMID:23266845

Zhou, Lilong; Liang, Runjuan; Ma, Zhanwei; Wu, Tinghua; Wu, Ying

2012-11-10

346

Carbon Dioxide and Ionic Liquid Refrigerants: Compact, Efficient Air Conditioning with Ionic Liquid-Based Refrigerants  

SciTech Connect

BEETIT Project: Notre Dame is developing an air-conditioning system with a new ionic liquid and CO2 as the working fluid. Synthetic refrigerants used in air conditioning and refrigeration systems are potent GHGs and can trap 1,000 times more heat in the atmosphere than CO2 alone—making CO2 an attractive alternative for synthetic refrigerants in cooling systems. However, operating cooling systems with pure CO2 requires prohibitively high pressures and expensive hardware. Notre Dame is creating a new fluid made of CO2 and ionic liquid that enables the use of CO2 at low pressures and requires minimal changes to existing hardware and production lines. This new fluid also produces no harmful emissions and can improve the efficiency of air conditioning systems— enabling new use of CO2 as a refrigerant in cooling systems.

None

2010-10-01

347

Femtosecond solvation dynamics in a neat ionic liquid and ionic liquid microemulsion: excitation wavelength dependence.  

PubMed

Solvation dynamics in a neat ionic liquid, 1-pentyl-3-methyl-imidazolium tetra-flouroborate ([pmim][BF4]) and its microemulsion in Triton X-100 (TX-100)/benzene is studied using femtosecond up-conversion. In both the neat ionic liquid and the microemulsion, the solvation dynamics is found to depend on excitation wavelength (lambda(ex)). The lambda(ex) dependence is attributed to structural heterogeneity in neat ionic liquid (IL) and in IL microemulsion. In neat IL, the heterogeneity arises from clustering of the pentyl groups which are surrounded by a network of cation and anions. Such a nanostructural organization is predicted in many recent simulations and observed recently in an X-ray diffraction study. In an IL microemulsion, the surfactant (TX-100) molecules aggregate in form of a nonpolar peripheral shell around the polar pool of IL. The micro-environment in such an assembly varies drastically over a short distance. The dynamic solvent shift (and average solvation time) in neat IL as well as in IL microemulsions decreases markedly as lambda(ex) increases from 375 to 435 nm. In a [pmim][BF4]/water/TX-100/benzene quaternary microemulsion, the solvation dynamics is slower than that in a microemulsion without water. This is ascribed to the smaller size of the water containing microemulsion. The anisotropy decay in an IL microemulsion is found to be faster than that in neat IL. PMID:17944511

Adhikari, Aniruddha; Sahu, Kalyanasis; Dey, Shantanu; Ghosh, Subhadip; Mandal, Ujjwal; Bhattacharyya, Kankan

2007-10-18

348

Room temperature inorganic ``quasi-molten salts`` as alkali-metal electrolytes  

SciTech Connect

Room temperature inorganic liquids of high ionic conductivity have been prepared by reacting Lewis acid AlCl with sulfonyl chlorides. The mechanism is not clear at this time since a crystal structure study of the 1:1 complex with CH{sub 3}SO{sub 2}Cl (T{sub m} = 30 C) is not consistent with a simple chloride transfer to create AlClO{sub 4}{sup {minus}} anions. The liquid is in a state somewhere between ionic and molecular. A new term quasi-molten salt is adopted to describe this state. A comparably conducting liquid can be made using BCL{sub 3} in place of AlCl{sub 3}. Unlike their organic counterparts based on ammonium cations (e.g., pyridinium or imidazolium) which reduce in the presence of alkali metals, this inorganic class of cation shows great stability against electrochemical reduction (ca. {minus}1.0 V vs. Li{sup +}/Li), with the useful consequence that reversible lithium and sodium metal deposition/stripping can be supported. The electrochemical window for these quasi-salts with AlCl{sub 3} ranges up to 5.0 V, and their room temperature conductivities exceed 10{sup {minus}4} S/cm. They dissolve lithium and sodium tetrachloroaluminates up to mole fraction {approximately} 0.6 at 100 C and intermediate compositions are permanently stable at ambient. The resultant lithium or sodium salt solutions exhibit electrochemical windows of 4.5--5.0 V vs. Li{sup +}/Li or Na{sup +}/Na and show room temperature conductivities of 10{sup {minus}3.0}--10{sup {minus}2.5} S/cm. In preliminary charge/discharge tests, the cell Li/``quasi-ionic liquid electrolyte``/Li{sub 1+x}Mn{sub 2}O{sub 4} showed a discharge capacity of ca. 110 mAh/(g of cathode) and sustained 80% of the initial capacity after 60 cycles, indicating that these quasi-molten salt-based electrolytes are promising candidates for alkali-metal batteries.

Xu, K.; Zhang, S.; Angell, C.A. [Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry

1996-11-01

349

Ionic liquids of cationic sandwich complexes.  

PubMed

Simple cationic sandwich complexes that contained alkyl- or halogen substituents provided ionic liquids (ILs) with the bis(perfluoroalkanesulfonyl)imide anion. Ferrocenium- and cobaltocenium ILs [M(C(5)H(4)R(1))(C(5)H(4)R(2))][Tf(2)N] (M=Fe, Co) and arene-ferrocenium ILs [Fe(C(5)H(4)R(1))(C(6)H(5)R(2))][Tf(2)N] were prepared and their physical properties were investigated. A detailed comparison of their thermal properties revealed the effects of molecular symmetry and substituents on their melting points. Their viscosity increased on increasing the length of the substituent on the cation and the perfluoroalkyl chain length on the anion. Upon cooling, ILs with low viscosities exhibited crystallization, whereas those with higher viscosities tended to exhibit glass transitions. Most of these salts showed phase transitions in the solid state. A magnetic-switching phenomenon was observed for the paramagnetic ferrocenium IL, which was associated with a liquid/solid transformation, based on the magnetic anisotropy of the ferrocenium cation. (57)Fe Mössbauer spectroscopy was applied to [Fe(C(5)H(4)nBu)(2)][Tf(2)N] to investigate the vibrational behavior of the iron atom in the crystal and glassy states of the ferrocenium IL. PMID:22517602

Inagaki, Takashi; Mochida, Tomoyuki; Takahashi, Masashi; Kanadani, Chikahide; Saito, Toshiaki; Kuwahara, Daisuke

2012-04-19

350

Soft ionization of thermally evaporated hypergolic ionic liquid aerosols  

SciTech Connect

Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1-Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim+][Tf2N?]ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (~;;0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicron aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally ?cooler? source of isolated intact ion pairs in the gas phase compared to effusive sources.

University of California; ERC, Incorporated, Edwards Air Force Base; Air Force Research Laboratory, Edwards Air Force Base; National Synchrotron Radiation Research Center (NSRRC); Institute of Chemistry, Hebrew University; Koh, Christine J.; Liu, Chen-Lin; Harmon, Christopher W.; Strasser, Daniel; Golan, Amir; Kostko, Oleg; Chambreau, Steven D.; Vaghjiani, Ghanshyam L.; Leone, Stephen R.

2011-07-19

351

Soft ionization of thermally evaporated hypergolic ionic liquid aerosols  

SciTech Connect

Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1- Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim+][Tf2N?] ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (~;;0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicron aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally ?cooler? source of isolated intact ion pairs in the gas phase compared to effusive sources.

University of California; ERC, Incorporated, Edwards Air Force Base; Air Force Research Laboratory, Edwards Air Force Base; National Synchrotron Radiation Research Center (NSRRC); Koh, Christine J.; Liu, Chen-Lin; Harmon, Christopher W.; Strasser, Daniel; Golan, Amir; Kostko, Oleg; Chambreau, Steven D.; L.Vaghjiani, Ghanshyam; Leone, Stephen R.

2012-03-16

352

Controlled synthesis of Mn3O4 nanoparticles in ionic liquids.  

PubMed

This work describes a simple one-step synthesis of Mn3O4 nanoparticles by thermal decomposition of [Mn(acac)2] (acac = acetylacetonate) using imidazolium ionic liquids (ILs) and a conventional solvent, oleylamine, for comparison. The Mn3O4 nanoparticles were characterized by XRD, ATR-FTIR, TEM, Raman, UV/VIS and magnetometry techniques. The addition of 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide IL (BMI·NTf2) yielded a smaller particle size (9.9 ± 1.8 nm) with better dispersion and more regular sizes than synthesis using oleylamine as the solvent (12.1 ± 3.0 nm). The complete conversion of the precursor to Mn3O4 nanoparticles occurred after 96 h at 180 °C for the reaction performed in BMI·NTf2. However, under these reaction conditions in oleylamine, no precursor was detected, but two different phases were observed: a major phase corresponding to Mn3O4 and a minor phase corresponding to MnO2. Magnetometry revealed that Mn3O4 nanoparticles synthesized in either oleylamine or BMI·NTf2 exhibited ferrimagnetic behavior at low temperatures, whereas they were paramagnetic at room temperature. As expected, the blocking temperature and the coercivity decreased with the size of nanoparticles. Our results demonstrate that reaction conditions such as time, and the nature of the ionic liquid play important roles in determining the size of Mn3O4 nanoparticles. PMID:23970370

Bussamara, Roberta; Melo, Wellington W M; Scholten, Jackson D; Migowski, Pedro; Marin, Graciane; Zapata, Maximiliano J M; Machado, Giovanna; Teixeira, Sérgio R; Novak, Miguel A; Dupont, Jairton

2013-09-24

353

Encapsulation Method of Glucose Oxidase Solution with Ionic Liquid Solvent and Direct Parylene Deposition  

NASA Astrophysics Data System (ADS)

We developed new encapsulation method of glucose oxidase solution with ionic liquid solvent and direct Parylene deposition for the application to MEMS glucose sensors. Glucose oxidase has been immobilized in gel or polymer on MEMS sensors, but its weak mechanical property has been remained to be solved. Then, its encapsulation has been demanded, but high-temperature MEMS bonding process (>150 °C) for packaging the solution is destructive to glucose oxidase which is denatured over 50 °C. To solve these problems, we encapsulated the glucose oxidase-ionic liquid solution with room-temperature packaging (25 °C) of direct Parylene deposition process. The glucose oxidase solution array with the area of 1 × 3 mm2 (approximately 1 ?l) was patterned on the hydrophilic-hydrophobic surface modification on the MEMS electrochemical electrodes in the use of the wetting phenomenon of the solution and, then, packaged by the chemical vapor deposition of 1.5 ?m Parylene. Parylene packages could be opened by pushing when used. The opened glucose oxidase solution reacted to 150 mM glucose solution, revealing the electrochemical potential of 150 mV. The sensitivity of our sensor ranged from 1 to 100 mM, which is the glucose concentration in the blood of the diabetic patients. Therefore, proposed encapsulation method exhibits the potential application to glucose sensor packages for diabetic patients.

Takamatsu, Seiichi; Takano, Hisanori; Binh-Khiem, Nguyen; Iwase, Eiji; Matsumoto, Kiyoshi; Shimoyama, Isao

354

Tribological properties of Ti-doped DLC coatings under ionic liquids lubricated conditions  

NASA Astrophysics Data System (ADS)

In this paper, titanium doped diamond-like carbon (Ti-DLC) coatings were prepared onto AISI 52100 steel substrates using medium frequency magnetic sputtering process, and were analyzed using the Raman and transmission electron microscope (TEM). Two kinds of 1,3-dialkyl imidazolium ionic liquids (ILs) were synthesized and evaluated as lubricants for Ti-DLC/steel contacts at room temperature, and PFPE as comparison lubricant. The tribological properties of the ILs were investigated using a ball-on-disk type UMT reciprocating friction tester. The results indicated that the ILs have excellent friction-reducing properties, the friction coefficient kept at a relatively stable value of 0.07-0.06, which was reduced approximately by 47% compared with perfluoropolyether (PFPE). The worn surfaces of Ti-DLC coatings were observed and analyzed using a MICROXAM-3D non-contact surface profiler, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The Ti-DLC coatings using ionic liquids lubricating systems are considered as potential lubricating system in vacuum and space moving friction pairs.

Feng, Xin; Xia, Yanqiu

2012-01-01

355

Ionic liquids based on polynitrile anions: hydrophobicity, low proton affinity, and high radiolytic resistance combined.  

PubMed

Ionic liquids (IL) are being considered as replacements for molecular diluents in spent nuclear fuel reprocessing. This development is hampered by the dearth of constituent anions that combine high hydrophobicity, low metal cation and proton affinity, and radiation resistance. We demonstrate that polynitrile anions have the potential to meet these challenges. Unlike the great majority of organic anions, such polynitrile anions are resistant to oxidative fragmentation during radiolysis, yielding stable N- and C-centered radicals. Moreover, their radical dianions (generated by reduction of the anions) generally undergo protonation in preference to elimination of the cyanide. This is in contrast to fluorinated anions (another large class of anions with low proton affinity), for which radiation-induced release of fluoride is a common occurrence. The "weak spot" of the polynitrile anions appears to be their excited-state dissociation, but at least one of these anions, 1,1,2,3,3-pentacyanopropenide, is shown to resist fragmentation in room temperature radiolysis. We suggest beginning the exploration of ionic liquids based on such polynitrile anions. PMID:23697390

Shkrob, Ilya A; Marin, Timothy W; Wishart, James F

2013-06-04

356

Molecular dynamics studies on the water mixtures of pharmaceutically important ionic liquid lidocaine HCl.  

PubMed

In this paper the molecular dynamics of a common local-anesthetic drug, lidocaine hydrochloride (LD-HCl), and its water mixtures were investigated. By means of broadband dielectric spectroscopy and calorimetric measurements it was shown that even a small addition of water causes a significant effect on the relaxation dynamics of analyzed protic ionic liquid. Apart from the two well-resolved relaxations (?- and ?-processes) and the ?-mode, identified as the JG-process, observed for anhydrous LD-HCl, a new relaxation peak (?) is visible in the dielectric spectra of aqueous mixtures of this drug. Additionally, the significant effect of the water on the glass transition temperature of LD-HCl was found. The sample characterized with mole fraction of water X(w) = 0.44 reveals the glass transition temperature T(g), 42 K lower than that of anhydrous material (307 K). Finally, it was shown that by amorphization of the hydrochloride salt of lidocaine it is possible to obtain its room temperature ionic liquid form. PMID:22424553

Wojnarowska, Z; Grzybowska, K; Hawelek, L; Swiety-Pospiech, A; Masiewicz, E; Paluch, M; Sawicki, W; Chmielewska, A; Bujak, P; Markowski, J

2012-03-26

357

Ultrafast and ultraslow proton transfer of pyranine in an ionic liquid microemulsion.  

PubMed

Effect of a room temperature ionic liquid (RTIL) and water on the ultrafast excited state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) inside a microemulsion is studied by femtosecond up-conversion. The microemulsion consists of the surfactant, triton X-100 (TX-100) in benzene (bz) and contains the RTIL, 1-pentyl-3-methyl-imidazolium tetrafluoroborate ([pmim] [BF(4)]) as the polar phase. In the absence of water, HPTS undergoes ultrafast ESPT inside the RTIL microemulsion (RTIL/TX-100/bz) and the deprotonated form (RO(-)) exhibits three rise components of 0.3, 14, and 375 ps. It is proposed that in the RTIL microemulsion, HPTS binds to the TX-100 at the interface region and participates in ultrafast ESPT to the oxygen atoms of TX-100. On addition of water an additional slow rise of 2150 ps is observed. Similar long rise component is also observed in water/TX-100/benzene reverse micelle (in the absence of [pmim] [BF(4)]). It is suggested that the added water molecules preferentially concentrate (trapped) around the palisade layer of the RTIL microemulsion. The trapped water molecules remain far from the HPTS both in the presence and absence of ionic liquid and gives rise to the slow component (2150 ps) of ESPT. Replacement of H(2)O by D(2)O causes an increase in the time constant of the ultraslow rise to 2350 ps. PMID:20499977

Sen Mojumdar, Supratik; Mondal, Tridib; Das, Atanu Kumar; Dey, Shantanu; Bhattacharyya, Kankan

2010-05-21

358

Development of Practical Supported Ionic Liquid Membranes: A Systematic Approach  

SciTech Connect

Supported liquid membranes (SLMs) are a class of materials that allow the researcher to utilize the wealth of knowledge available on liquid properties to optimize membrane performance. These membranes also have the advantage of liquid phase diffusivities, which are higher than those observed in polymers and grant proportionally greater permeabilities. The primary shortcoming of the supported liquid membranes demonstrated in past research has been the lack of stability caused by volatilization of the transport liquid. Ionic liquids, which may possess high CO2 solubility relative to light gases such as H2, are excellent candidates for this type of membrane since they are stable at elevated temperatures and have negligible vapor pressure. A study has been conducted evaluating the use of a variety of ionic liquids in supported ionic liquid membranes for the capture of CO2 from streams containing H2. In a joint project, researchers at the University of Notre Dame synthesized and characterized ionic liquids, and researchers at the National Energy Technology Laboratory incorporated candidate ionic liquids into supports and evaluated membrane performance for the resulting materials. Several steps have been taken in the development of practical supported ionic liquid membranes. Proof-of-concept was established by showing that ionic liquids could be used as the transport media in SLMs. Results showed that ionic liquids are suitable media for gas transport, but the preferred polymeric supports were not stable at temperatures above 135oC. The use of cross-linked nylon66 supports was found to produce membranes mechanically stable at temperatures exceeding 300oC but CO2/H2 selectivity was poor. An ionic liquid whose selectivity does not decrease with increasing temperature was needed, and a functionalized ionic liquid that complexes with CO2 was used. An increase in CO2/H2 selectivity with increasing temperature over the range of 37 to 85oC was observed and the dominance of a facilitated transport mechanism established. The presentation will detail membrane development, the effect of increasing transmembrane pressure, and preliminary results dealing with other gas pairs and contaminants.

Luebke, D.R.; Ilconich, J.B.; Myers, C.R.; Pennline, H.W.

2007-11-01

359

Tin Oxide Room Temperature Emitter Study.  

National Technical Information Service (NTIS)

The mechanisms of activation and electron emission of tin dioxide film room temperature emitters for cold-cathode application have been investigated. The structure, composition and electrical resistivity of vapor deposited films of various thicknesses and...

H. H. Kedesdy R. Sartore

1978-01-01

360

Search for a Room Temperature Superconductor.  

National Technical Information Service (NTIS)

A new model for a room temperature superconductor based on a sandwich or inclusion compound is discussed. It is reinforced by findings of areas of superconductivity in the sodium salts of cholic, desoxycholic, lithocholic and cholanic acids. An extrapolat...

S. Goldfein

1974-01-01

361

Search for a Room Temperature Superconductor.  

National Technical Information Service (NTIS)

A new model for a room temperature superconductor based on clathrates and intercalation compounds is discussed. It is reinforced not only by findings of superconductivity (yet to be confirmed) in sodium cholate, sodium desoxycholate and lithocholic acid b...

S. Goldfein

1973-01-01

362

How is charge transport different in ionic liquids and electrolyte solutions?  

PubMed

In this article we show that, analyzed in a barycentric reference frame, the deviation in conductivity measured directly from impedance experiments with respect to that estimated indirectly from NMR diffusion experiments has different origins in electrolyte solutions and pure salts. In the case of electrolyte solutions, the momentum conservation law is satisfied by solvent + ions. Instead, in a molten salt or ionic liquid momentum conservation must be satisfied solely by the ions. This has significant implications. While positively correlated motion of ions of opposite charge is a well justified explanation for the reduction in impedance conductivity in the case of electrolyte solutions, it is not so in the case of ionic liquids and molten salts. This work presents a set of equations that in the case of ionic liquids and molten salts can be used to obtain from direct measurements of impedance and NMR the distinct part of the diffusion coefficient matrix in the barycentric reference frame. In other words, by using experimentally measurable quantities, these equations allow us to access the motional coupling between ions for which there is no single direct experimental measurement technique. While equations of this type have been proposed before, the ones presented here can be easily derived from the momentum conservation law and linear response theory. Our results indicate that the decrease in the impedance conductivity with respect to NMR conductivity in ionic liquids and molten salts is due to anticorrelated motion of ions of same charge. This scenario is different in electrolyte solutions, where the positively correlated motion of ions of opposite charge makes a significant contribution to the decrease in the impedance conductivity. In contrast, in a system comprising a single binary salt (a room temperature ionic liquid or a molten salt), the cation-anion distinct diffusion coefficient is negative definite and opposes the contribution from the cation-cation and anion-anion distinct diffusion coefficients. This property of the cation-anion distinct diffusion coefficient in systems comprising just two ion-constituents holds true not just in the barycentric reference frame but also in any of the internal reference frames of nonequilibrium thermodynamics. PMID:22022889

Kashyap, Hemant K; Annapureddy, Harsha V R; Raineri, Fernando O; Margulis, Claudio J

2011-10-24

363

Electrokinetics of Correlated Electrolytes and Ionic Liquids  

NASA Astrophysics Data System (ADS)

Perhaps the most basic assumption of classical electrokinetic theory is the mean-field approximation, where the each ion feels only the electric field produced by the mean charge density (via Poisson's equation) rather than the fluctuating Coulomb forces with individual neighbors. Here, we present a simple continuum model for electrostatic correlations between finite-sized ions, which leads to a 4th order modified Poisson equation, convenient for the analysis of electrokinetic phenomena. When the mean-field approximation breaks down, e.g. due to large ion concentrations, large ion valences, and/or nanoscale confinement, the zeta potential loses its significance, and the model predicts that electro-osmotic flows are typically reduced - or even reversed - by correlation effects, compared to the prediction of the Helmholtz-Smoluchowski formula. This may help to explain the over-prediction of induced-charge electro-osmotic flows by classical models. An interesting limit of the model describes electro-osmosis in solvent-free ionic liquids and molten salts, which may be important in energy storage and electroactuation applications.

Storey, Brian; Bazant, Martin

2011-11-01

364

Room temperature ferromagnetic pure ZnO  

Microsoft Academic Search

Pure ZnO films were prepared by pulsed laser deposition on oxidized Si substrates under different oxygen pressure and substrate temperature. Clear room temperature ferromagnetism has been observed in the ZnO film prepared under high vacuum and room temperature. The observation of anomalous Hall effect confirms the intrinsic nature of the ferromagnetism. The photoluminescence and X-ray photoelectron spectroscopy spectra show the

Qingyu Xu; Zheng Wen; Liguo Xu; Jinlong Gao; Di Wu; Kai Shen; Teng Qiu; Shaolong Tang; Mingxiang Xu

2011-01-01

365

Determining Camera Gain in Room Temperature Cameras  

SciTech Connect

James R. Janesick provides a method for determining the amplification of a CCD or CMOS camera when only access to the raw images is provided. However, the equation that is provided ignores the contribution of dark current. For CCD or CMOS cameras that are cooled well below room temperature, this is not a problem, however, the technique needs adjustment for use with room temperature cameras. This article describes the adjustment made to the equation, and a test of this method.

Joshua Cogliati

2010-12-01

366

Studies of Latent Acidity and Neutral Buffered Chloroaluminate Ionic Liquids.  

National Technical Information Service (NTIS)

Studies on ionic liquids composed of aluminum chloride and 1-ethyl-3- methylimidazolium chloride were carried out, with emphasis on understanding and explaining acidity and latent acidity in 'neutral buffered' melts. It was found that alkaline earth, as w...

R. A. Osteryoung

2000-01-01

367

Minor Actinide Separations Using Ion Exchangers or Ionic Liquids.  

National Technical Information Service (NTIS)

This project seeks to determine if (1) inorganic-based ion exchange materials or (2) electrochemical methods in ionic liquids can be exploited to provide effective Am and Cm separations. Specifically, we seek to understand the fundamental structural and c...

A. Clearfield A. E. Visser D. T. Hobbs N. J. Bridges

2011-01-01

368

Electrochemical performance of a novel ionic liquid derived mesoporous carbon.  

PubMed

A novel nano-fibrillated mesoporous carbon (IFMC) was found to be an effective modifier in combination with ionic liquid 1-octylpyridinum hexafluorophosphate (OPFP) as a binder to give impregnated graphite electrodes with outstanding electrochemical performances. PMID:22314280

Karimi, Babak; Behzadnia, Hesam; Rafiee, Mohammad; Vali, Hojatollah

2012-02-07

369

Ionic Liquid Co-catalyzed Artificial Photosynthesis of CO  

NASA Astrophysics Data System (ADS)

The conversion of CO2 to chemical feedstocks is of great importance, which yet requires the activation of thermodynamically-stable CO2 by metal catalysts or metalloenzymes. Recently, the development of metal-free organocatalysts for use in CO2 activation under ambient conditions has opened new avenues for carbon fixation chemistry. Here, we report the capture and activation of CO2 by ionic liquids and coupling to photoredox catalysis to synthesize CO. The chemical nature of anions and the organic functional groups on the imidazolium cations of ionic liquids, together with reaction medium have been demonstrated to have remarkable effects on the activation and reduction of CO2. Considering almost unlimited structural variations of ionic liquids by a flexible combination of cations and anions, this photochemical pathway provides unique opportunities for carbon fixation by rationally-designed chemical systems via linking ionic liquid based materials with chromorphoric molecules in tackling the great challenges of artificial photosynthesis.

Lin, Jinliang; Ding, Zhengxin; Hou, Yidong; Wang, Xinchen

2013-01-01

370

High pressure studies of the transport properties of ionic liquids.  

PubMed

High pressure measurements have been made of viscosities, ion self-diffusion coefficients and electrical conductivities of ionic liquids, mainly of imidazolium salts. We review how these properties have been analysed in terms of the empirical Stokes-Einstein, Walden and Nernst-Einstein equations, and examine trends revealed by the phenomenological approach of velocity correlation coefficients and the more general theory of density scaling. Finally we examine the possibility of dynamic crossover in the transport properties of ionic liquids. PMID:22455034

Harris, Kenneth R; Kanakubo, Mitsuhiro

2012-01-01

371

Ionic Liquid as a Green Solvent for Lignin  

Microsoft Academic Search

This study examined the application of select ionic liquids (ILs) as aprotic green solvents for lignin. Dissolution experiments were carried out employing lignin isolated from pine kraft pulp. Up to 20 wt% lignin could be dissolved in [hmim][CF3SO3], [mmim][MeSO4] and [bmim][MeSO4]. For the [bmim]?containing ionic liquids, the order of lignin solubility for varying anions was: [MeSO4]>Cl?Br?[PF6], indicating that the solubility

Yunqiao Pu; Nan Jiang; Arthur J. Ragauskas

2007-01-01

372

Ionic liquid-catalyzed alkylation of isobutane with 2-butene  

Microsoft Academic Search

A detailed study of the alkylation of isobutane with 2-butene in ionic liquid media has been conducted using 1-alkyl-3-methylimidazolium halides–aluminum chloride encompassing various alkyl groups (butyl-, hexyl-, and octyl-) and halides (Cl, Br, and I) on its cations and anions, respectively. The emphasis has been to delineate the role of both cations and anions in this reaction. The ionic liquids

Kyesang Yoo; Vasudevan V Namboodiri; Rajender S Varma; Panagiotis G Smirniotis

2004-01-01

373

How ionic liquid changes properties of dense polydimethylsiloxane membrane?  

Microsoft Academic Search

The polydimethylsiloxane (PDMS) membranes containing 0, 10, 20 or 30 wt % of ionic liquid (benzyl-3-butylimidazolium tetrafluoroborate) were used for separation of butan-1-ol from water. Pervaporation selectivity increased and the butan-1-ol flux through the membrane raised with the increased content of [BBIM][BF4] in the PDMS-[BBIM][BF4] membranes (membrane from PDMS with immobilized ionic liquid).The PDMS-[BBIM][BF4] membrane showed high stability as well

M. Kohoutová; A. Sikora; Š. Hovorka; A. Randová; J. Schauer; M. Poloncarzová; P. Izák

2010-01-01

374

Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes  

NASA Astrophysics Data System (ADS)

Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene- b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there is incredible freedom in designing the block copolymer architecture in order to optimize the mechanical and other properties of the membrane without sacrificing conductivity. The derived scaling relationships are shown to be general for many block copolymer and ionic liquid chemistries. In certain cases, the mechanism of ion conduction in the ionic liquid is affected by block copolymer nanoconfinement. The introduction of excess neutral imidazole to [Im][TFSI] leads to enhanced proton conductivity as well as a high H+ transference number due to facilitated proton hopping between imidazole molecules. We show that there is increased proton hopping when the nonstoichiometric ionic liquid is confined to lamellar block copolymer nanodomains, which we hypothesize is due to changes in the hydrogen bond structure of the ionic liquid under confinement. This, in combination with unique ion aggregation behavior, leads to a lower activation energy for macroscopic ion transport compared to that in a corresponding homopolymer/ionic liquid mixture. Through this work, we further the understanding of the relationship between membrane composition, structure, and ion transport. The findings presented herein portend the rational design of nanostructured membranes having improved mechanical properties and conductivity.

Hoarfrost, Megan Lane

375

Local structures in ionic liquids probed and characterized by microscopic thermal diffusion monitored with picosecond time-resolved Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Vibrational cooling rate of the first excited singlet (S1) state of trans-stilbene and bulk thermal diffusivity are measured for seven room temperature ionic liquids, C2mimTf2N, C4mimTf2N, C4mimPF6, C5mimTf2N, C6mimTf2N, C8mimTf2N, and bmpyTf2N. Vibrational cooling rate measured with picosecond time-resolved Raman spectroscopy reflects solute-solvent and solvent-solvent energy transfer in a microscopic solvent environment. Thermal diffusivity measured with the transient grating method indicates macroscopic heat conduction capability. Vibrational cooling rate of S1 trans-stilbene is known to have a good correlation with bulk thermal diffusivity in ordinary molecular liquids. In the seven ionic liquids studied, however, vibrational cooling rate shows no correlation with thermal diffusivity; the observed rates are similar (0.082 to 0.12 ps-1 in the seven ionic liquids and 0.08 to 0.14 ps-1 in molecular liquids) despite large differences in thermal diffusivity (5.4-7.5 × 10-8 m2 s-1 in ionic liquids and 8.0-10 × 10-8 m2 s-1 in molecular liquids). This finding is consistent with our working hypothesis that there are local structures characteristically formed in ionic liquids. Vibrational cooling rate is determined by energy transfer among solvent ions in a local structure, while macroscopic thermal diffusion is controlled by heat transfer over boundaries of local structures. By using ``local'' thermal diffusivity, we are able to simulate the vibrational cooling kinetics observed in ionic liquids with a model assuming thermal diffusion in continuous media. The lower limit of the size of local structure is estimated with vibrational cooling process observed with and without the excess energy. A quantitative discussion with a numerical simulation shows that the diameter of local structure is larger than 10 nm. If we combine this lower limit, 10 nm, with the upper limit, 100 nm, which is estimated from the transparency (no light scattering) of ionic liquids, an order of magnitude estimate of local structure is obtained as 10 nm < L < 100 nm, where L is the length or the diameter of the domain of local structure.

Yoshida, Kyousuke; Iwata, Koichi; Nishiyama, Yoshio; Kimura, Yoshifumi; Hamaguchi, Hiro-O.

2012-03-01

376

Local structures in ionic liquids probed and characterized by microscopic thermal diffusion monitored with picosecond time-resolved Raman spectroscopy.  

PubMed

Vibrational cooling rate of the first excited singlet (S(1)) state of trans-stilbene and bulk thermal diffusivity are measured for seven room temperature ionic liquids, C(2)mimTf(2)N, C(4)mimTf(2)N, C(4)mimPF(6), C(5)mimTf(2)N, C(6)mimTf(2)N, C(8)mimTf(2)N, and bmpyTf(2)N. Vibrational cooling rate measured with picosecond time-resolved Raman spectroscopy reflects solute-solvent and solvent-solvent energy transfer in a microscopic solvent environment. Thermal diffusivity measured with the transient grating method indicates macroscopic heat conduction capability. Vibrational cooling rate of S(1) trans-stilbene is known to have a good correlation with bulk thermal diffusivity in ordinary molecular liquids. In the seven ionic liquids studied, however, vibrational cooling rate shows no correlation with thermal diffusivity; the observed rates are similar (0.082 to 0.12 ps(-1) in the seven ionic liquids and 0.08 to 0.14 ps(-1) in molecular liquids) despite large differences in thermal diffusivity (5.4-7.5 × 10(-8) m(2) s(-1) in ionic liquids and 8.0-10 × 10(-8) m(2) s(-1) in molecular liquids). This finding is consistent with our working hypothesis that there are local structures characteristically formed in ionic liquids. Vibrational cooling rate is determined by energy transfer among solvent ions in a local structure, while macroscopic thermal diffusion is controlled by heat transfer over boundaries of local structures. By using "local" thermal diffusivity, we are able to simulate the vibrational cooling kinetics observed in ionic liquids with a model assuming thermal diffusion in continuous media. The lower limit of the size of local structure is estimated with vibrational cooling process observed with and without the excess energy. A quantitative discussion with a numerical simulation shows that the diameter of local structure is larger than 10 nm. If we combine this lower limit, 10 nm, with the upper limit, 100 nm, which is estimated from the transparency (no light scattering) of ionic liquids, an order of magnitude estimate of local structure is obtained as 10 nm < L < 100 nm, where L is the length or the diameter of the domain of local structure. PMID:22423845

Yoshida, Kyousuke; Iwata, Koichi; Nishiyama, Yoshio; Kimura, Yoshifumi; Hamaguchi, Hiro-o

2012-03-14

377

Determination of sudan dyes in red wine and fruit juice using ionic liquid-based liquid-liquid microextraction and high-performance liquid chromatography.  

PubMed

The liquid-liquid microextraction (LLME) was developed for extracting sudan dyes from red wine and fruit juice. Room temperature ionic liquid was used as the extraction solvent. The target analytes were determined by high-performance liquid chromatography. The extraction parameters were optimized. The optimal conditions are as follows: volume of [C(6)MIM][PF(6)] 50 ?L; the extraction time 10 min; pH value of the sample solution 7.0; NaCl concentration in sample solution 5%. The extraction recoveries for the analytes in red wine and fruit samples are 86.79-108.28 and 68.54-85.66%, whereas RSDs are 1.42-5.12 and 1.43-6.19%, respectively. The limits of detection and quantification were 0.428 and 1.426 ng/mL for sudan I, 0.938 and 3.127 ng/mL for sudan II, 1.334 and 4.445 ng/mL for sudan III, 1.454 and 4.846 ng/mL for sudan IV, respectively. Compared with conventional liquid-liquid extraction (CLLE) and ultrasonic extraction (UE), when LLME was applied, the sample amount was less (LLME: 4 mL; CLLE: 10 mL; UE: 10 mL), the extraction time was shorter (LLME: 15 min; CLLE: 110 min; UE: 50 min) and the extraction solvent amount was less (LLME: 0.05 mL IL; CLLE: 15 mL hexane; UE: 20 mL hexane). The proposed method offers a simple, rapid and efficient sample preparation for determining sudan dyes in red wine and fruit juice samples. PMID:21656676

Sun, Shuo; Wang, Ying; Yu, Wenzhi; Zhao, Tianqi; Gao, Shiqian; Kang, Mingqin; Zhang, Yupu; Zhang, Hanqi; Yu, Yong

2011-06-08

378

Polymer electrolyte batteries for operation at and below room temperature  

NASA Astrophysics Data System (ADS)

A polymeric electrolyte with good ionic conductivity at and below room temperature has been developed for use in lithium cells. This novel material combines polymeric properties, such as flexibility and physical strength, with a wide electrochemical stability window and the ability to sustain good interfacial electrode contact. By appropriate modifications, it has been possible to prepare composite cathodes incorporating the new polymeric electrolyte. This in turn has led to the construction of flexible, thin-film cells based on the lithium/MnO2 couple.

Barker, D. J.

379

Carbon Dioxide Separation with Supported Ionic Liquid Membranes  

SciTech Connect

Supported liquid membranes are a class of materials that allow the researcher to utilize the wealth of knowledge available on liquid properties as a direct guide in the development of a capture technology. These membranes also have the advantage of liquid phase diffusivities higher than those observed in polymeric membranes which grant proportionally greater permeabilities. The primary shortcoming of the supported liquid membranes demonstrated in past research has been the lack of stability caused by volatilization of the transport liquid. Ionic liquids, which possess high carbon dioxide solubility relative to light gases such as hydrogen, are an excellent candidate for this type of membrane since they have negligible vapor pressure and are not susceptible to evaporation. A study has been conducted evaluating the use of several ionic liquids, including 1-hexyl-3-methyl-imidazolium bis(trifuoromethylsulfonyl)imide, 1-butyl-3-methyl-imidazolium nitrate, and 1-ethyl-3-methyl-imidazolium sulfate in supported ionic liquid membranes for the capture of carbon dioxide from streams containing hydrogen. In a joint project, researchers at the University of Notre Dame lent expertise in ionic liquid synthesis and characterization, and researchers at the National Energy Technology Laboratory incorporated candidate ionic liquids into supports and evaluated the resulting materials for membrane performance. Initial results have been very promising with carbon dioxide permeabilities as high as 950 barrers and significant improvements in carbon dioxide/hydrogen selectivity over conventional polymers at 37C and at elevated temperatures. Results include a comparison of the performance of several ionic liquids and a number of supports as well as a discussion of innovative fabrication techniques currently under development.

Luebke, D.R.; Ilconich, J.B.; Myers, C.R.; Pennline, H.W.

2007-04-01

380

Aqueous, Room Temperature Deposition of Silicon, Molybdenum and Germanium onto Aluminum Substrates  

NASA Astrophysics Data System (ADS)

Electrochemical deposition of active materials such as Si, Mo and Ge is notoriously difficult, so they are typically deposited using expensive vacuum methods such as chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and magnetron sputtering. However, for most materials, electrochemical deposition has significant advantages of cost, scalability, and manufacturability. There are two main challenges in depositing these materials from aqueous electrolytes at room temperature, namely their highly cathodic standard reduction potential and the formation of native oxides. This has led researchers to use non-aqueous electrolytes such as organic solvents, room temperature ionic liquids (RTILs), and high temperature molten salts. However, these have drawbacks over aqueous electrolytes such as high cost, low conductivity, flammability, and corrosive behavior. During my PhS studies, these two challenges were overcome by using the galvanic method of deposition and by including HF in the electrolyte. Si thin films are employed in a variety of technologies, including microelectronic and photovoltaic devices, Li ion battery anodes, and corrosion-resistant coatings. A galvanic and a combined galvanic/electroless method of Si deposition were developed using aqueous electrolytes at room temperature to obtain nanoporous and compact films, respectively. These films were characterized to understand the surface morphology, thickness, crystallinity, growth rate, composition and nucleation behavior. Approximately 7-10 µm thick compact Si films were achieved with a deposition time of around 28 hours. The galvanic method of deposition was also extended to deposit compact Mo films. Mo thin films have a number of technological applications, including back contacts for CIGS/CZTS photovoltaic devices and corrosion-resistant coatings. Mo thin films were also thoroughly characterized and approximately 4.5 µm thick films were obtained after 3 hours. Similar to Si depostion, a galvanic method of deposition and the galvanic/electroless method of deposition was tested for the deposition of Ge. However no Ge deposit could be consistently obtained, probably due to oxyanion formation in aqueous hexaflurogermante solution.

Krishnamurthy, Aarti Krishna

381

Toward radiation-resistant ionic liquids. Radiation stability of sulfonyl imide anions.  

PubMed

Room-temperature hydrophobic ionic liquids (ILs) are considered for processing of spent nuclear fuel, including as possible replacements for molecular diluents in liquid-liquid extraction. This application requires radiation stability of the constituent ions. Previous research indicated that most of the anions that are currently used in the synthesis of ILs are prone to fragmentation under prolonged radiation exposure, which causes deterioration of the corresponding ILs. An exception to this general rule is phthalimide; unfortunately, this anion is too basic to be useful for extraction solvents, as these separations involve acidic conditions. The acidity of the imide can be increased by replacing the carbonyl groups by sulfonyl groups, which incidentally transform these imides into familiar artificial sweeteners such as saccharin. In the present study, we use electron paramagnetic resonance spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry to assess the radiation stability of ILs based on such "sweet" sulfonyl imide anions. Our results suggest that saccharinate and o-benzenedisulfonimide are remarkably stable to radiation-induced fragmentation. PMID:22747437

Shkrob, Ilya A; Marin, Timothy W; Chemerisov, Sergey D; Hatcher, Jasmine; Wishart, James F

2012-07-13

382

Raidiation-Induced Fragmentation of Diamide Extraction Agents in Ionic Liquid Diluents  

SciTech Connect

N,N,N',N'-Tetraalkyldiglycolamides are extracting agents that are used for liquid-liquid extraction of trivalent metal ions in wet processing of spent nuclear fuel. This application places such agents in contact with the decaying radionuclides, causing radiolysis of the agent in the organic diluent. Recent research seeks to replace common molecular diluents (such as n-dodecane) with hydrophobic room-temperature ionic liquids (ILs), which have superior solvation properties. In alkane diluents, rapid radiolytic deterioration of diglycolamide agents can be inhibited by addition of an aromatic cosolvent that scavenges highly reactive alkane radical cations before these oxidize the extracting agent. Do aromatic ILs exhibit a similar radioprotective effect? To answer this question, we used electron paramagnetic resonance spectroscopy to study the fragmentation pathways in radiolysis of neat diglycolamides, their model compounds, and their solutions in the ILs. Our study indicates that aromatic ILs do not protect these types of solutes from extensive radiolytic damage. Previous research indicated a similar lack of protection for crown ethers, whereas the ILs readily protected di- and trialkyl phosphates (another large class of metal-extracting agents). Our analysis of these unanticipated failures suggests that new types of organic anions are required in order to formulate ILs capable of radioprotection for these classes of solutes. This study is a cautionary tale of the fallacy of analogical thinking when applied to an entirely new and insufficiently understood class of chemical materials.

Bell, Jason R [ORNL; Dai, Sheng [ORNL; Shkrob, Ilya A. [Argonne National Laboratory (ANL); Marin, Timothy W. [Argonne National Laboratory (ANL); Luo, Huimin [ORNL; Hatcher, Jasmine [Brookhaven National Laboratory (BNL); Rimmer, R. Dale [Brookhaven National Laboratory (BNL); Wishart, James F. [Brookhaven National Laboratory (BNL)

2012-01-01

383

Radiation-induced fragmentation of diamide extraction agents in ionic liquid diluents.  

PubMed

N,N,N',N'-Tetraalkyldiglycolamides are extracting agents that are used for liquid-liquid extraction of trivalent metal ions in wet processing of spent nuclear fuel. This application places such agents in contact with the decaying radionuclides, causing radiolysis of the agent in the organic diluent. Recent research seeks to replace common molecular diluents (such as n-dodecane) with hydrophobic room-temperature ionic liquids (ILs), which have superior solvation properties. In alkane diluents, rapid radiolytic deterioration of diglycolamide agents can be inhibited by addition of an aromatic cosolvent that scavenges highly reactive alkane radical cations before these oxidize the extracting agent. Do aromatic ILs exhibit a similar radioprotective effect? To answer this question, we used electron paramagnetic resonance spectroscopy to study the fragmentation pathways in radiolysis of neat diglycolamides, their model compounds, and their solutions in the ILs. Our study indicates that aromatic ILs do not protect these types of solutes from extensive radiolytic damage. Previous research indicated a similar lack of protection for crown ethers, whereas the ILs readily protected di- and trialkyl phosphates (another large class of metal-extracting agents). Our analysis of these unanticipated failures suggests that new types of organic anions are required in order to formulate ILs capable of radioprotection for these classes of solutes. This study is a cautionary tale of the fallacy of analogical thinking when applied to an entirely new and insufficiently understood class of chemical materials. PMID:22296406

Shkrob, Ilya A; Marin, Timothy W; Bell, Jason R; Luo, Huimin; Dai, Sheng; Hatcher, Jasmine L; Rimmer, R Dale; Wishart, James F

2012-02-13

384

Ionic liquid analogues formed from hydrated metal salts.  

PubMed

A dark green, viscous liquid can be formed by mixing choline chloride with chromium(III) chloride hexahydrate and the physical properties are characteristic of an ionic liquid. The eutectic composition is found to be 1:2 choline chloride/chromium chloride. The viscosity and conductivity are measured as a function of temperature and composition and explained in terms of the ion size and liquid void volume. The electrochemical response of the ionic liquid is also characterised and it is shown that chromium can be electrodeposited efficiently to yield a crack-free deposit. This approach could circumvent the use of chromic acid for chromium electroplating, which would be a major environmental benefit. This method of using hydrated metal salts to form ionic liquids is shown to be valid for a variety of other salt mixtures with choline chloride. PMID:15281161

Abbott, Andrew P; Capper, Glen; Davies, David L; Rasheed, Raymond K

2004-08-01

385

Synthesis and characterization of hybrid materials based on 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid and Dawson-type tungstophosphate K[HPWO].18HO and K[PWO].13HO  

Microsoft Academic Search

In this study, we synthesized hybrid materials using well-Dawson polyoxometalates (POMs), K[HPWO].18HO or K[PWO].13HO and a room temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF]). K, W, P and CHN elemental analysis showed that one mole of [HPWO] reacts with 6 moles of BMIM{sup +} and one mole of [PWO] reacts with 4 moles of BMIM{sup +} to form, respectively, K[BMIM]HPWO and

Malika Ammam; Jan Fransaer

2011-01-01

386

Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids.  

PubMed

Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented. PMID:21298175

Pinkert, André; Ang, Keng L; Marsh, Kenneth N; Pang, Shusheng

2011-02-07

387

Method and apparatus using an active ionic liquid for algae biofuel harvest and extraction  

DOEpatents

The invention relates to use of an active ionic liquid to dissolve algae cell walls. The ionic liquid is used to, in an energy efficient manner, dissolve and/or lyse an algae cell walls, which releases algae constituents used in the creation of energy, fuel, and/or cosmetic components. The ionic liquids include ionic salts having multiple charge centers, low, very low, and ultra low melting point ionic liquids, and combinations of ionic liquids. An algae treatment system is described, which processes wet algae in a lysing reactor, separates out algae constituent products, and optionally recovers the ionic liquid in an energy efficient manner.

Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

2012-11-06

388

Aggregation behavior of a fluorinated surfactant in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid.  

PubMed

The cationic fluorinated surfactant, FC-4, unlike other surfactants, forms micelles in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf2N). Surface tension, freeze-fracture transmission electron microscopy, 19F NMR, 1H NMR, and Fourier transform infrared measurements revealed that (i) the FC-4 cation forms an ion pair with the Tf2N anion, (ii) the ion pairs undergo association to form premicellar aggregates, and (iii) the premicellar aggregates transform into micelles at the critical micelle concentration (CMC). The thermodynamic parameters for micelle formation derived from the temperature dependence of the CMC demonstrated that the solvophobic interaction between the solvophobic tails of the surfactant molecules is rather weak in bmimTf2N compared with other ionic liquids, in accordance with the observation that surfactants do not readily form micelles in bmimTf2N. The fact that FC-4 forms micelles in such an inconvenient solvent is attributed to the ion-pair formation between the surfactant cation and the ionic liquid anion. PMID:19441844

Li, Na; Zhang, Shaohua; Zheng, Liqiang; Inoue, Tohru

2009-09-15

389

Molecular dynamics simulation of imidazolium-based ionic liquids. I. Dynamics and diffusion coefficient  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are used to study the dynamics and transport properties of 12 room-temperature ionic liquids of the 1-alkyl-3-methylimidazolium [amim]+ (alkyl=methyl, ethyl, propyl, and butyl) family with PF6-, NO3-, and Cl- counterions. The explicit atom transferable force field of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] is used in the simulations. In this first part, the dynamics of the ionic liquids are characterized by studying the mean-square displacement (MSD) and the velocity autocorrelation function (VACF) for the centers of mass of the ions at 400 K. Trajectory averaging was employed to evaluate the diffusion coefficients at two temperatures from the linear slope of MSD(t) functions in the range of 150-300 ps and from the integration of the VACF(t) functions at 400 K. Detailed comparisons are made between the diffusion results from the MSD and VACF methods. The diffusion coefficients from the integration of the VACFs are closer to experimental values than the diffusion coefficients calculated from the slope of MSDs. Both methods can show good agreement with experiment in predicting relative trends in the diffusion coefficients and determining the role of the cation and anion structures on the dynamical behavior of this family of ionic liquids. The MSD and self-diffusion of relatively heavier imidazolium cations are larger than those of the lighter anions from the Einstein results, except for the case of [bmim][Cl]. The cationic transference number generally decreases with temperature, in good agreement with experiments. For the same anion, the cationic transference numbers decrease with increasing length of the alkyl chain, and for the same cation, the trends in the cationic transference numbers are [NO3]-<[Cl]-<[PF6]-. The trends in the diffusion coefficient in the series of cations with identical anions are [emim]+>[pmim]+>[bmim]+ and those for anions with identical cations are [NO3]->[PF6]->[Cl]-. The [dmim]+ has a relatively low diffusion coefficient due to its symmetric structure and good packing in the liquid phase. The major factor for determining the magnitude of the self-diffusion is the geometric shape of the anion of the ionic liquid. Other important factors are the ion size and the charge delocalization in the anion.

Kowsari, M. H.; Alavi, Saman; Ashrafizaadeh, Mahmud; Najafi, Bijan

2008-12-01

390

Effects and mechanism characterization of ionic liquids as mobile phase additives for the separation of matrine-type alkaloids by liquid chromatography.  

PubMed

The mechanism for the separation of matrine-type alkaloids (sophoridine, sophoramine, sophocarpine, matrine, and oxymatrine) on a C(18) column with a mobile phase containing room temperature ionic liquids (RTILs) as additive was studied in the current work by investigating several factors that influenced chromatographic behavior, including mobile phase pH, buffer solution concentration, ionic liquid concentration, and length of alkyl groups in RTILs. Peak efficiency was selected as the criterion for chromatographic efficiency whereas peak efficiency was also selected for triethylamine (TEA). The addition of RTILs in a mobile phase demonstrated superior effects on the separation of these basic compounds because of the increase in peak efficiency. The difference between RTILs and TEA and the changes in retention factors caused by the additives concentration, depending on the acidity of the mobile phase, showed the dual nature of the ionic liquids. This allowed both the constituting anion and cation to participate in the retention mechanism. Furthermore, the chromatographic behaviors of analytes with a mobile phase containing RTILs having different lengths of alkyl groups at different concentrations, complied with the stoichiometric displacement model for retention (SDM-R). This clarified the significant role of competitive adsorption between solutes and additives on the stationary phase. PMID:22018979

Bian, Min; Zhang, Zunjian; Yin, Hao

2011-10-01

391

Electric control of magnetism at room temperature  

PubMed Central

In the single-phase multiferroics, the coupling between electric polarization (P) and magnetization (M) would enable the magnetoelectric (ME) effect, namely M induced and modulated by E, and conversely P by H. Especially, the manipulation of magnetization by an electric field at room-temperature is of great importance in technological applications, such as new information storage technology, four-state logic device, magnetoelectric sensors, low-power magnetoelectric device and so on. Furthermore, it can reduce power consumption and realize device miniaturization, which is very useful for the practical applications. In an M-type hexaferrite SrCo2Ti2Fe8O19, large magnetization and electric polarization were observed simultaneously at room-temperature. Moreover, large effect of electric field-controlled magnetization was observed even without magnetic bias field. These results illuminate a promising potential to apply in magnetoelectric devices at room temperature and imply plentiful physics behind them.

Wang, Liaoyu; Wang, Dunhui; Cao, Qingqi; Zheng, Yuanxia; Xuan, Haicheng; Gao, Jinlong; Du, Youwei

2012-01-01

392

Tetraalkylphosphonium polyoxometalate ionic liquids : novel, organic-inorganic hybrid materials  

Microsoft Academic Search

Pairing of a Keggin or Lindqvist polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation is shown to yield the first members of a new family of ionic liquids (ILs). Detailed characterization of one of them, an ambient-temperature 'liquid POM' comprising the Lindqvist salt of the trihexyl(tetradecyl) phosphonium cation, by voltammetry, viscometry, conductimetry, and thermal analysis indicates that it exhibits conductivity

Paul G. Rickert; Mark R. Antonio; Millicent A. Firestone; Karrie-Ann Kubatko; Tomasz Szreder; James F. Wishart; Mark L. Dietz

2007-01-01

393

Carbon Dioxide Separation with Supported Ionic Liquid Membranes  

SciTech Connect

A practical form of CO2 capture at water-gas shift conditions in the IGCC process could serve the dual function of producing a pure CO2 stream for sequestration and forcing the equilibrium-limited shift reaction to completion enriching the stream in H2. The shift temperatures, ranging from the low temperature shift condition of 260°C to the gasification condition of 900°C, limit capture options by diminishing associative interactions which favor removal of CO2 from the gas stream. Certain sorption interactions, such as carbonate formation, remain available but generally involve exceptionally high sorbent regeneration energies that contribute heavily to parasitic power losses. Carbon dioxide selective membranes need only establish an equilibrium between the gas phase and sorption states in order to transport CO2, giving them a potential energetic advantage over other technologies. Supported liquid membranes take advantage of high, liquid phase diffusivities and a solution diffusion mechanism similar to that observed in polymeric membranes to achieve superior permeabilities and selectivites. The primary shortcoming of the supported liquid membranes demonstrated in past research has been the lack of stability caused by volatilization of the transport liquid. Ionic liquids, which possess high CO2 solubility relative to light gases such as H2, are excellent candidates for this type of membrane since they have negligible vapor pressure and are not susceptible to evaporation. A study has been conducted evaluating the use of ionic liquids including 1-hexyl-3-methyl-imidazolium bis(trifuoromethylsulfonyl)imide in supported ionic liquid membranes for the capture of CO2 from streams containing H2. In a joint project, researchers at the University of Notre Dame synthesized and characterized ionic liquids, and researchers at the National Energy Technology Laboratory incorporated candidate ionic liquids into supports and evaluated the resulting materials for membrane performance. Improvements to the ionic liquid and support have allowed testing of these supported ionic liquid membranes at temperatures up to 300°C without loss of support mechanical stability or degradation of the ionic liquid. Substantial improvements in selectivity have also been observed at elevated temperature with the best membrane currently achieving optimum performance at 75°C.

Luebke, D.R.; Ilconich, J.B.; Pennline, H.W.; Myers, C.R.

2007-05-01

394

Extraction of uranium (VI) by 1.1 M tri- n-butylphosphate\\/ionic liquid and the feasibility of recovery by direct electrodeposition from organic phase  

Microsoft Academic Search

The diluent characteristics and the wide electrochemical window of the room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide (bmimNTf2), has been exploited for the extraction of uranium (VI) from nitric acid medium using 1.1M solution of tri-n-butylphosphate (TBP) in bmimNTf2, followed by direct electrodeposition as uranium oxide from organic phase. The extraction of uranium (VI) with 1.1M TBP\\/bmimNTf2 has been studied

P. Giridhar; K. A. Venkatesan; S. Subramaniam; T. G. Srinivasan; P. R. Vasudeva Rao

2008-01-01

395

Syntheses of very dense halogenated liquids.  

PubMed

A family of halogenated liquids with densities ranging from 1.95 to 2.80 g cm(-3) was readily synthesized by a one-pot procedure. These liquids exhibit characteristics of ionic liquids with melting/transition points lower than room temperature, long liquid ranges, and marked hydrolytic and thermal stabilities. PMID:15357622

Ye, Chengfeng; Shreeve, Jean'ne M

2004-09-17

396

Recent developments of ionic liquids in oligosaccharide synthesis: the sweet side of ionic liquids.  

PubMed

The area of ionic liquid (IL) research has seen tremendous growth over the last few decades. The development of novel ILs with new and attractive physical and chemical properties has had a direct impact on organic synthesis. In particular, ILs have had many applications in carbohydrate chemistry including their use as solvents for dissolving high molecular weight carbohydrate polymers such as cellulose and as solvents and catalysts in oligosaccharide synthesis. In this area, ILs have been involved in protecting group manipulation reactions as well as glycosidic couplings leading to new methodologies and enhanced procedures. In addition, ILs have been successfully utilized as solution-phase purification supports. This review focuses on the most recent advances in the application of ILs to oligosaccharide synthesis. This is an emerging area that offers great promise at addressing some of the obstacles that remain on the path towards the automation of oligosaccharide synthesis. PMID:23685038

Galan, M Carmen; Jones, Rachel A; Tran, Anh-Tuan

2013-04-17

397

Physicochemical properties and toxicities of hydrophobicpiperidinium and pyrrolidinium ionic liquids  

SciTech Connect

Some properties are reported for hydrophobic ionic liquids (IL) containing 1-methyl-1-propyl pyrrolidinium [MPPyrro]{sup +}, 1-methyl-1-butyl pyrrolidinium [MBPyrro]{sup +}, 1-methyl-1-propyl piperidinium [MPPip]{sup +}, 1-methyl-1-butyl piperidinium [MBPip]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPyrro]{sup +} and 1-methyl-1-octylpiperidinium [MOPip]{sup +} cations. These liquids provide new alternatives to pyridinium and imidazolium ILs. High thermal stability of an ionic liquid increases safety in applications like rechargeable lithium-ion batteries and other electrochemical devices. Thermal properties, ionic conductivities, viscosities, and mutual solubilities with water are reported. In addition, toxicities of selected ionic liquids have been measured using a human cancer cell-line. The ILs studied here are sparingly soluble in water but hygroscopic. We show some structure-property relationships that may help to design green solvents for specific applications. While ionic liquids are claimed to be environmentally-benign solvents, as yet few data have been published to support these claims.

Salminen, Justin; Papaiconomou, Nicolas; Kumar, R. Anand; Lee,Jong-Min; Kerr, John; Newman, John; Prausnitz, John M.

2007-06-25

398

X-ray photoelectron spectroscopy of ferrocenyl- and ferrocenium-based ionic liquids.  

PubMed

X-ray photoelectron spectroscopy (XPS) is used to study a series of five 1-(ferrocenylmethyl)-3-methylimidazolium- and 1-(ferroceniummethyl)-3-methylimidazolium-based salts. All samples emit good photoelectron fluxes with sharp, well-resolved photoelectron peaks. Due to the low volatility of imidazolium-salts at ambient temperature, no modification of the XP spectrometer was required. Two of the salts exhibit supercooling behaviour, allowing XPS to be recorded at room temperature on liquid samples without the need for charge neutralisation. The photoelectron peaks can be assigned to the component atoms of the salts, based on previous studies on ferrocene, ferrocenium-compounds and ionic liquids. Oxidation of the ferrocenyl moiety to ferrocenium shiftsthe Fe 2p and cyclopentadienyl C 1s photoelectron peaks to higher binding energy but does not affect the imidazolium and anion peaks. Under charge-neutralisation conditions, in which the sample is flooded with low-energy electrons, the ferrocenium moiety of the salt 1-(ferroceniummethyl)-3-methylimidazolium di(hexafluorophosphate) is partially reduced. PMID:22287261

Taylor, Alasdair W; Licence, Peter

2012-01-27

399

Ab initio study on an excited-state intramolecular proton-transfer reaction in ionic liquid.  

PubMed

An excited-state intramolecular proton transfer (ESIPT) reaction of 4'-N,N-dimethylamino-3-hydroxyflavone in room temperature ionic liquid is theoretically investigated using RISM-SCF-SEDD, which is a hybrid method of molecular liquid theory and ab initio molecular orbital theory. The photo-excitation and proton-transfer processes are computed by considering the solvent fluctuation. The calculated absorption and emission energy are in good agreement with the experiments. The changes in the dipole moment indicate that the drastic solvation relaxation is accompanied by the excitation and an ESIPT process, which is consistent with the remarkable dynamic Stokes shift observed in the experiments. We calculated the nonequilibrium free-energy contour as a function of the proton coordinate and the solvation coordinate. We conclude that although immediately after the excitation the barrier height of the ESIPT process is relatively small, the barrier becomes larger as the solvation relaxation to the excited normal state proceeds. The solvation relaxation process is also investigated on the basis of microscopic solvation structure obtained by RISM calculations. PMID:23697807

Hayaki, Seigo; Kimura, Yoshifumi; Sato, Hirofumi

2013-05-22

400

Lithium ion conducting ionic electrolytes  

DOEpatents

A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors.

Angell, C. Austen (Mesa, AZ); Xu, Kang (Tempe, AZ); Liu, Changle (Tulsa, OK)

1996-01-01

401

DNA origami impedance measurement at room temperature  

Microsoft Academic Search

The frequency response of triangular DNA origami is obtained at room temperature. The sample shows a high impedance at low frequencies, e.g., at zero frequency 20 G?, which decreases almost linearly with the logarithm of the frequency reaching a low and flat value at 100 kHz where the impedance turns from capacitive to resistive, concluding that DNA can be used

Alfredo D. Bobadilla; Edson P. Bellido; Norma L. Rangel; Hong Zhong; Michael L. Norton; Alexander Sinitskii; Jorge M. Seminario

2009-01-01

402

DNA origami impedance measurement at room temperature  

Microsoft Academic Search

The frequency response of triangular DNA origami is obtained at room temperature. The sample shows a high impedance at low frequencies, e.g., at zero frequency 20 GOmega, which decreases almost linearly with the logarithm of the frequency reaching a low and flat value at 100 kHz where the impedance turns from capacitive to resistive, concluding that DNA can be used

Alfredo D. Bobadilla; Edson P. Bellido; Norma L. Rangel; Hong Zhong; Michael L. Norton; Alexander Sinitskii; Jorge M. Seminario

2009-01-01

403

Stability of polypyrrole soft actuators in ionic liquids  

NASA Astrophysics Data System (ADS)

Characteristics of electrochemomechanical deformation (ECMD) of polypyrrole films using ionic liquids are reported. The PPy film prepared by electrodeposition in an ionic liquid (1-Butyl-1-methylpyrrolidinium bis(trifluorometylsulfonyl)imide, BMPTFSI) was compact and high density. The other film prepared from LiTSFI/methyl benzoate and dimethyl phthalate mixed solvents was porous and low density. Both films demonstrated a stable ECMD in the ionic liquid. The strain of ECMD was 3-5% and superimposed on a creeping, showing a typical behaviour of cation movement. The Strains of ECMD in both films operated in a mixed electrolyte of BMPTFSI and propylene carbonate were enhanced up to 17- 25 %, showing anion movement. However, the large strain decreased upon several electrochemical cycles. The results were discussed in terms of swelling of the PPy film by solvents and loss of electrochemical activity.

Kaneto, Keiicgi; Takashima, Wataru

2012-04-01

404

Chiral Ionic Liquids in Chromatographic Separation and Spectroscopic Discrimination  

NASA Astrophysics Data System (ADS)

Chiral ionic liquids (CILs) are a subclass of ionic liquids (ILs) in which the cation, anion, or both may be chiral. The chirality can be central, axial, or planar. CILs possess a number of unique advantageous properties which are inherited from ionic liquids including negligible vapor pressure, wide liquidus temperature range, high thermal stability, and high tunability. Due to their dual functionalities as chiral selectors and chiral solvents simultaneously, CILs recently have been widely used both in enantiomeric chromatographic separation and in chiral spectroscopic discrimination. In this chapter, the various applications of CILs in chiral chromatographic separations such as GC, HPLC, CE, and MEKC are reviewed. The applications of CILs in enantiomeric spectroscopic discrimination using techniques such as NMR, fluorescence, and NIR are described. In addition, chiral recognition and separation mechanism using the CILs as chiral selectors or chiral solvents is also discussed.

Li, Min; Bwambok, David K.; Fakayode, Sayo O.; Warner, Isiah M.

405

Physical Properties of Ionic Liquids Consisting of the 1-Butyl-3-Methylimidazolium Cation with Various Anions and the Bis(trifluoromethylsulfonyl)imide Anion with Various Cations  

SciTech Connect

Physical properties of 4 room-temperature ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various perfluorinated anions and the bis(trifluoromethylsulfonyl)imide (Tf2N-) anion with 12 pyrrolidinium-, ammonium-, and hydroxyl-containing cations are reported. Electronic structure methods are used to calculate properties related to the size, shape, and dipole moment of individual ions. Experimental measurements of phase-transition temperatures, densities, refractive indices, surface tensions, solvatochromic polarities based on absorption of Nile Red, 19F chemical shifts of the Tf2N- anion, temperature-dependent viscosities, conductivities, and cation diffusion coefficients are reported. Correlations among the measured quantities as well as the use of surface tension and molar volume for estimating Hildebrand solubility parameters of ionic liquids are also discussed.

Jin, Hui [Pennsylvania State University, University Park, PA; O'Hare, Bernie [Pennsylvania State University, University Park, PA; Dong, Jing [Pennsylvania State University, University Park, PA; Arzhantsev, Sergei [Pennsylvania State University, University Park, PA; Baker, Gary A [ORNL; Wishart, James F. [Brookhaven National Laboratory (BNL); Benesi, Alan [Pennsylvania State University, University Park, PA; Maroncelli, Mark [Pennsylvania State University, University Park, PA

2008-01-01

406

Growth of Gold Nanosheets and Nanopolyhedra in Pyrrolidinium-Based Ionic Liquids: Investigation of the Cation Effect on the Resulting Morphologies  

SciTech Connect

Large gold nanosheets and small gold polyhedra have been successfully synthesized in room-temperature ionic liquids (ILs) by an ionothermal reduction of HAuCl{sub 4} under N{sub 2} atmosphere, without using any additives. The effect of the organic cation on the final morphologies of the gold particles has been studied, and a series of pyrrolidinium-, imidazolium-, and quaternary amine-based ionic liquids have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. Our results show that these ILs favor the anisotropic growth of gold by acting as template agents and that only gold microspheres can be obtained with the IL containing a reductive functionality.

Bouvy, Claire [ORNL; Baker, Gary A [ORNL; Yin, Hongfeng [ORNL; Dai, Sheng [ORNL

2010-01-01

407

A green and efficient protocol for the synthesis of quinoxaline, benzoxazole and benzimidazole derivatives using heteropolyanion-based ionic liquids: as a recyclable solid catalyst.  

PubMed

In this paper, we introduce two nonconventional ionic liquid compounds which are composed of propane sulfonate functionalized organic cations and heteropolyanions as green solid acid catalysts for the highly efficient and green synthesis of 2,3-disubstitutedquinoxaline derivatives. These ionic liquids are in the solid state at room temperature and the synthesis is carried out via the one-pot condensation reaction of various o-phenylenediamine with 1,2-diketone derivatives. Benzoxazole and benzimidazole derivatives were also synthesized by these novel catalysts via the one-pot condensation from reaction orthoester with o-aminophenol (synthesis of benzoxazole derivatives) and ophenylenediamine (synthesis of benzimidazole derivatives). All experiments successfully resulted in the desired products. The described novel synthesis method has several advantages of safety, mild condition, high yields, short reaction times, simplicity and easy workup compared to the traditional method of synthesis. PMID:23547570

Vahdat, Seyed Mohammad; Baghery, Saeed

2013-09-01

408

Fixation of CO2 by electrocatalytic reduction and electropolymerization in ionic liquid-H2O solution.  

PubMed

The electrocatalytic synthesis of low-density polyethylene (LDPE) from carbon dioxide on a nanostructured (ns)TiO2 film electrode was investigated by controlled potential electrolysis in a solvent mixture of water and the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMI]BF4) at room temperature under ambient pressure. Under these conditions, the nsTiO2 film is remarkably efficient and selective for the electroreduction of CO2. The current efficiency for the formation of the electrolytic product is about 8-14% at -1.50 V (vs SCE). The electrocatalytic activity of the electrode in the electrochemical reduction of CO2 was investigated by cyclic voltammetry (CV), and the probable electrode reaction mechanism is discussed. PMID:18605207

Chu, Daobao; Qin, Guoxu; Yuan, Ximei; Xu, Mai; Zheng, Peng; Lu, Jia

2008-01-01