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1

Ionic liquids and reactive azeotropes: the continuity of the aprotic and protic classes.  

PubMed

In this work, we explore the relations between the acid-base reactions implicit in the definition of protic ionic liquids and their solutions, the existence of reactive azeotropy, and the continuity between the aprotic and protic classes of ionic liquids. The profound impact caused by this type of homogenous azeotropy on the fluid phase behaviour (liquid-gas equilibria) of this class of compounds is also discussed. PMID:20145863

Canongia Lopes, José N; Rebelo, Luís Paulo N

2010-01-15

2

Surface interactions, corrosion processes and lubricating performance of protic and aprotic ionic liquids with OFHC copper  

NASA Astrophysics Data System (ADS)

In order to select possible candidates for use as lubricants or as precursors of surface coatings, the corrosion and surface interactions of oxygen-free high conductivity (OFHC) copper with two new protic (PIL) and four aprotic (APIL) room-temperature ionic liquids have been studied. The PILs, with no heteroatoms in their composition, are the triprotic di[(2-hydroxyethyl)ammonium] succinate (MSu) and the diprotic di[bis-(2-hydroxyethyl)ammonium] adipate (DAd). The four APILs contain imidazolium cations with short or long alkyl chain substituents and reactive anions: 1-ethyl-3-methylimidazolium phosphonate ([EMIM]EtPO3H); 1-ethyl-3-methylimidazolium octylsulfate ([EMIM]C8H17SO4); 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM]BF4) and 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF6). Contact angles between the ionic liquids and OFHC copper surface were measured. Mass and roughness changes of OFHC copper after 168 h in contact with the ionic liquids have been determined. Copper surfaces were studied by XRD, SEM–EDX and XPS surface analysis. FTIR spectra of the liquid phases recovered after being in contact with the copper surface were compared with that of the neat ionic liquids. The lowest corrosion rate is observed for the diprotic ammonium adipate PIL (DAd), which gives low mass and surface roughness changes and forms adsorbed layers on copper, while the triprotic ammonium succinate salt (MSu) produces a severe corrosive attack by reaction with copper to form a blue crystalline solid, which has been characterized by FTIR and thermal analysis (TGA). All imidazolium APILs react with copper, with different results as a function of the anion. As expected, [EMIM]C8H17SO4 reacts with copper to form the corresponding copper sulphate salt. [EMIM]EtPO3H produces severe corrosion to form a phosphonate–copper soluble phase. [HMIM]BF4 gives rise to the highest roughness increase of the copper surface. [HMIM]PF6 shows the lowest mass and roughness changes of the four imidazolium ionic liquids due to the formation of a solid layer containing phosphorus and fluorine. The results described in the present study are in agreement with the outstanding good tribological performance of the diprotic ammonium adipate (DAd) ionic liquid for the copper–copper contact, in pin-on-disc tests, preventing wear and giving a very low friction coefficient of 0.01. Under the same conditions, [HMIM]PF6 gives a friction value of 0.03, while the reactivity of MSu towards copper produces maximum friction peaks of 0.05. In contrast with the absence of surface damage on copper, an abrasive wear mechanism is observed for MSu and [HMIM]PF6. The results confirm a better lubricating performance for a lower corrosion rate.

Espinosa, Tulia; Sanes, José; Jiménez, Ana-Eva; Bermúdez, María-Dolores

2013-05-01

3

A wave-function based approach for polarizable charge model: Systematic comparison of polarization effects on protic, aprotic, and ionic liquids  

NASA Astrophysics Data System (ADS)

We first describe a wave-function based formalism of polarizable charge model by starting from the Hartree product ansatz for the total wave function and making the second-order expansion of individual molecular energies with the use of partial charge operators. The resulting model is shown to be formally equivalent to the charge response kernel model that starts from the linear-response approximation to partial charges, and also closely related to a family of fluctuating charge models that are based on the electronegativity equalization principle. We then apply the above model to a systematic comparison of polarization effects on qualitatively different liquids, namely, protic solvents (water and methanol), an aprotic polar solvent (acetonitrile), and imidazolium-based ionic liquids. Electronic polarization is known to decelerate molecular motions in conventional solvents while it accelerates them in ionic liquids. To obtain more insights into these phenomena, we consider an effective decomposition of total polarization energy into molecular contributions, and show that their statistical distribution is well-correlated with the acceleration/deceleration of molecular motions. In addition, we perform effective nonpolarizable simulations based on mean polarized charges, and compare them with fully polarizable simulations. The result shows that the former can reproduce structural properties of conventional solvents rather accurately, while they fail qualitatively to reproduce acceleration of molecular motions in ionic liquids.

Nakano, Hiroshi; Yamamoto, Takeshi; Kato, Shigeki

2010-01-01

4

Influence of Solvent on Ion Aggregation and Transport in PY15TFSI Ionic Liquid-Aprotic Solvent Mixtures.  

PubMed

Molecular dynamics (MD) simulations using a many-body polarizable APPLE&P force field have been performed on mixtures of the N-methyl-N-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PY15TFSI) ionic liquid (IL) with three molecular solvents: propylene carbonate (PC), dimethyl carbonate (DMC), and acetonitrile (AN). The MD simulations predict density, viscosity, and ionic conductivity values that agree well with the experimental results. In the solvent-rich regime, the ionic conductivity of the PY15TFSI-AN mixtures was found to be significantly higher than the conductivity of the corresponding -PC and -DMC mixtures, despite the similar viscosity values obtained from both the MD simulations and experiments for the -DMC and -AN mixtures. The significantly lower conductivity of the PY15TFSI-DMC mixtures, as compared to those for PY15TFSI-AN, in the solvent-rich regime was attributed to the more extensive ion aggregation observed for the -DMC mixtures. The PY15TFSI-DMC mixtures present an interesting case where the addition of the organic solvent to the IL results in an increase in the cation-anion correlations, in contrast to what is found for the mixtures with PC and AN, where ion motion became increasingly uncorrelated with addition of solvent. A combination of pfg-NMR and conductivity measurements confirmed the MD simulation predictions. Further insight into the molecular interactions and properties was also obtained using the MD simulations by examining the solvent distribution in the IL-solvent mixtures and the mixture excess properties. PMID:23941158

Borodin, Oleg; Henderson, Wesley A; Fox, Eric T; Berman, Marc; Gobet, Mallory; Greenbaum, Steve

2013-08-28

5

Electrochemical behaviour of tetra- n-butylammonium nonaflate as an ionic liquid and as a supporting electrolyte in aprotic solvents: A comparative study  

Microsoft Academic Search

Tetra-n-butylammonium nonaflate was synthesized, characterized and employed as a neat ionic liquid and as supporting electrolyte in acetonitrile, N,N?-dimethylformamide, propylene carbonate and sulfolane media. The electrochemical oxidation of ferrocene and hydroquinone as well as the electrochemical reduction of anthracene were investigated in all the media. Good correlation is established between the charge transfer rate, diffusion coefficient of all the three

Arumugam Manivel; David Velayutham; Michael Noel

2011-01-01

6

Decoupling of charge transport from structural dynamics in protic ionic liquids  

NASA Astrophysics Data System (ADS)

Broadband dielectric spectroscopy, differential scanning calorimetry and rheology are employed to investigate charge transport and dynamics in protic and aprotic ionic liquids. While the structural ?-relaxation rates and the characteristic charge diffusion rates coincide for aprotic ionic liquids, the latter is found to be more than 100 times for the protic ionic liquids studied. Moreover, the analysis of protic ionic liquids revealed a decoupling of temperature dependence of ionic transport from that of structural relaxation with the degree of decoupling increasing with fragility of the liquid. The potential technological impact of these results will be discussed.

Sangoro, Joshua; Sokolov, Alexei; Kremer, Friedrich; Paluch, Marian

2013-03-01

7

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

8

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

9

Carbon Dioxide Capture by Superbase-Derived Protic Ionic Liquids  

SciTech Connect

Protic ionic liquids (PILs) from a superbase and fluorinated alcohol, imidazole, pyrrolinone, or phenol were designed to capture CO{sub 2} based on the reactivity of their anions to CO{sub 2}. These PILs are capable of rapid and reversible capture of about one equivalent of CO{sub 2}, which is superior to those sorption systems based on traditional aprotic ILs.

Dai, Sheng [ORNL; Luo, Huimin [ORNL; Li, Haoran [Zhejiang University; Wang, Chongmin [Pacific Northwest National Laboratory (PNNL); Jiang, Deen [ORNL

2010-01-01

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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

21

Vibrational study of ionic association in polar aprotic solvents. Isocyanate complexes of non-transition-metal ions  

Microsoft Academic Search

Complexes between alkaline-earth-metal ions M2+ and cyanate OCN? in aprotic solvents are studied by infrared spectrometry in the ?(CN) region (2150–2250 cm?1). In dimethylsulphoxide (DMSO) and hexamethylphosphotriamide (HMPT) isocyanate MNCO ion pairs exhibit a specific ?(CN) band while M(NCO)2 species usually have two ?(CN) bands. Pure alkaline earth cyanates are in part dissociated into MNCO+ and OCN? in DMSO. When

Corinne Le Borgne; Martial Chabanel

1997-01-01

22

Ionic liquids as oxidic media for electron transfer studies  

NASA Astrophysics Data System (ADS)

We review the basic ideas underlying the electron free energy level diagrams that have been found useful in considering the thermodynamics of redox processes in molten silicates and related high temperature ionic liquid (IL) solvents, and then show how closely they link to behavior observable in ambient temperature ionic liquids. Much of the information available on redox levels in molten oxides has been gleaned from chemical analysis and spectroscopic species distribution studies, but it is simpler to obtain the data electrochemically. Here, we report some cyclic voltammetry measurements of the Fe(II)/Fe(III) redox equilibrium in aprotic ionic liquids whose anions provide oxide environments for the redox species that are of different electronic polarizability character from the high temperature solvents, and relate the observations to those of the earlier studies. Quasi-reversible behavior is found in each of the cases studied. As might be expected, the Fe(II)/Fe(III) equilibrium experiences a more basic environment in an acetate IL than it experiences in any of the common glassforming oxide media, while triflate anions contrast by providing a more acid environment than does the most acid of the molten oxide glassformers studied (an alkali phosphate). The difference can amount to well over 1 V, suggesting the possibility of a ``basicity cell'' where the same redox couple locates in anode and cathode compartments of the cell, and only the anion environment is different.

Ueno, Kazuhide; Angell, C. Austen

2012-06-01

23

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

24

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

25

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

26

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

27

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.

28

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

29

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

30

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

31

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

32

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

33

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

34

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

35

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

36

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

37

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

38

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

39

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

40

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

41

A quantitative ionicity scale for liquid chloride salts.  

PubMed

Knowledge of ionicity is requisite for successful identification of those salt qualities required to design and couple the most appropriate fluid for performance of an intended chemical function. We report on utilisation of (35)Cl(-) quadrupolar coupling constants (C(Q)) to quantitatively assess the ionicities of given chloride salts, by exploiting the electronic response of the quadrupolar chlorine atom as a function of its immediate chemical environment. We find that protic salts in particular, like their aprotic analogues, are highly ionised, while at the same time being highly associated, in stark contrast to literature reports claiming in general that they are of sub-ionic origin. PMID:22886109

Ingman, Petri; Driver, Gordon W

2012-08-10

42

Physical and electrochemical properties of N-alkyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ionic liquids: PY13FSI and PY14FSI.  

PubMed

Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or 4 for butyl) and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized. The ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ionic liquids. Both ionic liquids crystallize readily on cooling and undergo several solid-solid phase transitions on heating prior to melting. PY13FSI and PY14FSI are found to melt at -9 and -18 degrees C, respectively. The thermal stability of PY13FSI and PY14FSI is notably lower than for the analogous salts with the bis(trifluoromethanesulfonyl)imide (TFSI(-)), N(SO2CF3)2(-), anion. Both ionic liquids have a relatively wide electrochemical stability window of approximately 5 V. PMID:18828629

Zhou, Qian; Henderson, Wesley A; Appetecchi, Giovanni B; Montanino, Maria; Passerini, Stefano

2008-10-02

43

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

44

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

45

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

46

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

47

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

48

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

49

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

50

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

51

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

52

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

53

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

54

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

55

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

56

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

57

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

58

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

59

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

60

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

61

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

62

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

63

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

64

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

65

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

66

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

67

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

68

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

69

Pseudocapacitive mechanism of manganese oxide in 1-ethyl-3-methylimidazolium thiocyanate ionic liquid electrolyte studied using X-ray photoelectron spectroscopy.  

PubMed

The electrochemical behavior of anodically deposited manganese oxide was studied in pyrrolidinium formate (P-HCOO), 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6), and 1-ethyl-3-methylimidazolium thiocyanate (EMI-SCN) ionic liquids (ILs). The experimental data indicate that the Mn oxide electrode showed ideal pseudocapacitive performance in aprotic EMI-SCN IL. In a potential window of approximately 1.5 V, the oxide specific capacitance, evaluated using cyclic voltammetry and chronopotentiometry, was about 55 F/g. The electrochemical energy storage reaction was examined using X-ray photoelectron spectroscopy (XPS). It was confirmed that the SCN- anions, instead of the EMI+ cations, were the primary working species that can become incorporated into the oxide and thus compensate the Mn3+/Mn4+ valent state variation upon the charge-discharge process. According to the analytical results, a pseudocapacitive mechanism of Mn oxide in the SCN- based aprotic IL was proposed. PMID:19621902

Chang, Jeng-Kuei; Lee, Ming-Tsung; Tsai, Wen-Ta; Deng, Ming-Jay; Cheng, Hui-Fang; Sun, I-Wen

2009-10-01

70

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

71

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

72

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

73

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

74

Liquid-liquid phase separation in solutions of ionic liquids: phase diagrams, corresponding state analysis and comparison with simulations of the primitive model.  

PubMed

Phase diagrams of ionic solutions of the ionic liquid C(18)mim(+)NTF(2)(-) (1-n-octadecyl-3-methyl imidazolium bistrifluormethylsulfonylimide) in decalin, cyclohexane and methylcyclohexane are reported and compared with that of solutions of other imidazolium ionic liquids with the anions NTF(2)(-), Cl(-) and BF4(-) in arenes, CCl(4), alcohols and water. The phase diagrams are analysed presuming Ising criticality and taking into account the asymmetry of the phase diagrams. The resulting parameters are compared with simulation results for equal-sized charged hard spheres in a dielectric continuum, the restricted primitive model (RPM) and the primitive model (PM) that allows for ions of different size. In the RPM temperature scale the critical temperatures vary almost linearly with the dielectric permittivity of the solvent. The RPM critical temperatures of the solutions in non-polar solvents are very similar, somewhat below the RPM value. Correlations with the boiling temperatures of the solvents and a dependence on the length of the side chain of the imidazolium cations show that dispersion interactions modify the phase transition, which is mainly determined by Coulomb forces. Critical concentrations, widths of the phase diagrams and the slopes of the diameter are different for the solutions in protic and aprotic solvents. The phase diagrams of the solutions in alcohols and water get a lower critical solution point when represented in RPM variables. PMID:21715854

Schröer, W; Vale, V R

2009-09-30

75

Liquid-liquid phase separation in solutions of ionic liquids: phase diagrams, corresponding state analysis and comparison with simulations of the primitive model  

NASA Astrophysics Data System (ADS)

Phase diagrams of ionic solutions of the ionic liquid C18mim+NTF2- (1-n-octadecyl-3-methyl imidazolium bistrifluormethylsulfonylimide) in decalin, cyclohexane and methylcyclohexane are reported and compared with that of solutions of other imidazolium ionic liquids with the anions NTF2-, Cl- and BF4- in arenes, CCl4, alcohols and water. The phase diagrams are analysed presuming Ising criticality and taking into account the asymmetry of the phase diagrams. The resulting parameters are compared with simulation results for equal-sized charged hard spheres in a dielectric continuum, the restricted primitive model (RPM) and the primitive model (PM) that allows for ions of different size. In the RPM temperature scale the critical temperatures vary almost linearly with the dielectric permittivity of the solvent. The RPM critical temperatures of the solutions in non-polar solvents are very similar, somewhat below the RPM value. Correlations with the boiling temperatures of the solvents and a dependence on the length of the side chain of the imidazolium cations show that dispersion interactions modify the phase transition, which is mainly determined by Coulomb forces. Critical concentrations, widths of the phase diagrams and the slopes of the diameter are different for the solutions in protic and aprotic solvents. The phase diagrams of the solutions in alcohols and water get a lower critical solution point when represented in RPM variables.

Schröer, W.; Vale, V. R.

2009-10-01

76

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

77

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

78

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

79

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

80

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

81

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

82

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

83

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

84

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

85

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

86

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

87

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

88

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

89

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

90

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

91

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

92

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

93

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

94

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

95

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

96

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

97

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

98

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

99

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

100

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

101

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

102

Protic ionic liquids: preparation, characterization, and proton free energy level representation.  

PubMed

We give a perspective on the relations between inorganic and organic cation ionic liquids (ILs), including members with melting points that overlap around the borderline 100 degrees C. We then present data on the synthesis and properties (melting, boiling, glass temperatures, etc.) of a large number of an intermediate group of liquids that cover the ground between equimolar molecular mixtures and ILs, depending on the energetics of transfer of a proton from one member of the pair to the other. These proton-transfer ILs have interesting properties, including the ability to serve as electrolytes in solvent-free fuel cell systems. We provide a basis for assessing their relation to aprotic ILs by means of a Gurney-type proton-transfer free energy level diagram, with approximate values of the energy levels based on free energy of formation and pK(a) data. The energy level scheme allows us to verify the relation between solvent-free acidic and basic electrolytes, and the familiar aqueous variety, and to identify neutral protic electrolytes that are unavailable in the case of aqueous systems. PMID:17417896

Belieres, Jean-Philippe; Angell, C Austen

2007-04-07

103

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

104

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

105

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

106

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

107

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

108

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

109

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

110

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

111

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

112

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

113

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

114

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

115

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

116

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

117

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

118

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

119

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

120

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

121

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

122

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

123

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

124

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

125

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

126

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

127

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

128

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

129

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

130

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

131

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

132

Physicochemical properties determined by ?pKa for protic ionic liquids based on an organic super-strong base with various Brønsted acids.  

PubMed

Neutralization of an organic super-strong base, 1,8-diazabicyclo-[5,4,0]-undec-7-ene (DBU), with different Brønsted acids affords a novel series of protic ionic liquids (PILs) with wide variations in the ?pK(a) of the constituent amine and acids. The physicochemical properties of these PILs, such as thermal properties, density, conductivity, viscosity, self-diffusion coefficient, vibrational stretching frequency, and (1)H-chemical shifts of the N-H bond, have been studied in detail. The generated PILs have melting temperatures below 100 °C, and six are liquids at ambient temperatures. Thermogravimetric analyses (TGA) conducted under isothermal and programmed heating conditions have shown that PILs with ?pK(a)? 15 exhibit good thermal stability similar to aprotic ionic liquids. For instance, PILs with ?pK(a) > 20 show remarkably high short-term thermal stability up to ca. 450 °C under a nitrogen atmosphere. The viscosity, ionic conductivity, and molar conductivity of the PILs fit well with the Vogel-Fulcher-Tamman equation for their dependencies on temperature. The relative cationic and anionic self-diffusion coefficients of the PILs estimated by the pulsed-field gradient spin-echo (PGSE) NMR method appear to be dependent on the structure and strength of the Brønsted acids. Evaluation of the ionicity based on both the Walden plot and PGSE-NMR revealed that it increases until ?pK(a) becomes 15 for the PILs. PMID:22415497

Miran, Muhammed Shah; Kinoshita, Hiroshi; Yasuda, Tomohiro; Susan, Md Abu Bin Hasan; Watanabe, Masayoshi

2012-03-14

133

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

134

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

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

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

137

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

138

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

139

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.

140

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

141

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

142

Development of ionic liquid-based lithium battery prototypes  

Microsoft Academic Search

The lab-scale manufacturing of Li\\/LiFePO4 and Li4Ti5O12\\/LiFePO4 stacked battery prototypes and their performance characterization are described here. The prototypes were realized in the frame of an European Project devoted to the development of greener and safer lithium batteries, based on ionic liquid electrolytes, for integration with photovoltaic panels. N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) and N-butyl-N-methylpyrrolidinium bis(fluoro-methanesulfonyl)imide (PYR14FSI), selected as the ionic liquids

G.-T. Kim; S. S. Jeong; M.-Z. Xue; A. Balducci; M. Winter; S. Passerini; F. Alessandrini; G. B. Appetecchi

143

Toxicological evaluation of magnetic ionic liquids in human cell lines.  

PubMed

Magnetic ionic liquids (MILs) are new solvents with an interesting broad of applications however their toxicity is still an open issue. In this paper we report the toxicity of [C(8)MIM] and [Choline-C(n)] based magnetic ionic liquids assessed in two human cell lines: normal skin fibroblasts (CRL-1502) and colorectal adenocarcinoma cells (CaCo-2), acquiring this last characteristics of human enterocytes after differentiation. The results showed that [CoCl(4)] and [MnCl(4)] are more prone to generate cytotoxicity. PMID:23561571

Frade, Raquel F M; Simeonov, Svilen; Rosatella, Andreia A; Siopa, Filipa; Afonso, Carlos A M

2013-04-03

144

Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure.  

PubMed

A series of alkyltributylphosphonium chloride ionic liquids, prepared from tributylphosphine and the respective 1-chloroalkane, C(n)H(2n+1)Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl)phosphonium chloride is detailed. PMID:22679620

Adamová, Gabriela; Gardas, Ramesh L; Nieuwenhuyzen, Mark; Puga, Alberto V; Rebelo, Luís Paulo N; Robertson, Allan J; Seddon, Kenneth R

2012-06-07

145

Carbon-polymer-ionic liquid composite as a motion sensor  

NASA Astrophysics Data System (ADS)

High surface area carbon, ionic liquid and polymer are incorporated in an electromechanically active composite. This laminate bends when voltage (typically less than 3 V) is applied between the electrodes, and generates voltage and current when bent with an external force. By suitable optimization, the material can be used either as an actuator, energy storage element (supercapacitor) or sensor. Strain caused by bending promotes dislocation of ions in the micropores of carbon. As a result, the charge separation occurs because ions of ionic liquid are likely trapped in the micropores of diameters close to the ion sizes.

Must, Indrek; Kaasik, Friedrich; Põldsalu, Inga; Johanson, Urmas; Punning, Andres; Aabloo, Alvo

2012-03-01

146

Capturing CO2: conventional versus ionic-liquid based technologies  

NASA Astrophysics Data System (ADS)

Since CO2 facilitates pipeline corrosion and contributes to a decrease of the calorific value of gaseous fuels, its removal has become an issue of significant economic importance. The present review discusses various types of traditional CO2 capture technologies in terms of their efficiency, complexity in system design, costs and environmental impact. The focus is hereby not only on conventional approaches but also on emerging "green" solvents such as ionic liquids. The suitability of different ionic liquids as gas separation solvents is discussed in the present review and a description on their synthesis and properties in terms of CO2 capture is provided. The bibliography includes 136 references.

Privalova, E. I.; Mäki-Arvela, P.; Murzin, Dmitry Yu; Mikkhola, J. P.

2012-05-01

147

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

148

Study on gas separation by supported liquid membranes applying novel ionic liquids  

Microsoft Academic Search

In the present study, the permeability of H2, N2 and CO2 was investigated through supported liquid membranes prepared by using four types of novel ionic liquids (VACEM 42, VACEM 44, VACEM 47, VACEM 58) under various gas phase pressures (2.2 bar, 1.8 bar, 1.4 bar) and temperatures (30°C, 40°C, 50°C). VACEM type ionic liquids, which are built up of a

P. Cserjési; N. Nemestóthy; A. Vass; Zs. Csanádi; K. Bélafi-Bakó

2009-01-01

149

Charge Transport and Glassy Dynamics in Ionic Liquids  

SciTech Connect

Ionic liquids (ILs) exhibit unique features such as low melting points, low vapor pressures, wide liquidus temperature ranges, high thermal stability, high ionic conductivity, and wide electrochemical windows. As a result, they show promise for use in variety of applications: as reaction media, in batteries and supercapacitors, in solar and fuel cells, for electrochemical deposition of metals and semiconductors, for protein extraction and crystallization, and many others. Because of the ease with which they can be supercooled, ionic liquids offer new opportunities to investigate long-standing questions regarding the nature of the dynamic glass transition and its possible link to charge transport. Despite the significant steps achieved from experimental and theoretical studies, no generally accepted quantitative theory of dynamic glass transition to date has been capable of reproducing all the experimentally observed features. In this Account, we discuss recent studies of the interplay between charge transport and glassy dynamics in ionic liquids as investigated by a combination of several experimental techniques including broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance, dynamic mechanical spectroscopy, and differential scanning calorimetry. Based on EinsteinSmoluchowski relations, we use dielectric spectra of ionic liquids to determine diffusion coefficients in quantitative agreement with independent pulsed field gradient nuclear magnetic resonance measurements, but spanning a broader range of more than 10 orders of magnitude. This approach provides a novel opportunity to determine the electrical mobility and effective number density of charge carriers as well as their types of thermal activation from the measured dc conductivity separately. We also unravel the origin of the remarkable universality of charge transport in different classes of glass-forming ionic liquids.

Sangoro, Joshua R [ORNL; Kremer, Friedrich [University of Leipzig

2012-01-01

150

Charge transport and glassy dynamics in ionic liquids.  

PubMed

Ionic liquids (ILs) exhibit unique features such as low melting points, low vapor pressures, wide liquidus temperature ranges, high thermal stability, high ionic conductivity, and wide electrochemical windows. As a result, they show promise for use in variety of applications: as reaction media, in batteries and supercapacitors, in solar and fuel cells, for electrochemical deposition of metals and semiconductors, for protein extraction and crystallization, and many others. Because of the ease with which they can be supercooled, ionic liquids offer new opportunities to investigate long-standing questions regarding the nature of the dynamic glass transition and its possible link to charge transport. Despite the significant steps achieved from experimental and theoretical studies, no generally accepted quantitative theory of dynamic glass transition to date has been capable of reproducing all the experimentally observed features. In this Account, we discuss recent studies of the interplay between charge transport and glassy dynamics in ionic liquids as investigated by a combination of several experimental techniques including broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance, dynamic mechanical spectroscopy, and differential scanning calorimetry. Based on Einstein-Smoluchowski relations, we use dielectric spectra of ionic liquids to determine diffusion coefficients in quantitative agreement with independent pulsed field gradient nuclear magnetic resonance measurements, but spanning a broader range of more than 10 orders of magnitude. This approach provides a novel opportunity to determine the electrical mobility and effective number density of charge carriers as well as their types of thermal activation from the measured dc conductivity separately. We also unravel the origin of the remarkable universality of charge transport in different classes of glass-forming ionic liquids. PMID:22082024

Sangoro, Joshua R; Kremer, Friedrich

2011-11-14

151

Origins of Symmetry in Polymer Ionic Liquid Phase Diagrams  

NASA Astrophysics Data System (ADS)

Recent experimental work [Lee et al. Macromolecules 45, 3627 (2012)] reveals rather symmetric looking coexistence curves for poly(ethylene oxide) in [EMIM][BF4]. This is in marked contrast to solutions involving non-ionic solvents, which show a characteristic and strong asymmetry, correlated with the molecular weight disparity between the two components. Using our simple theoretical approach we show that the special character of this systems derives from two thermodynamically-based properties. First, we find that the ionic solvent has a considerably stronger cohesive energy densities than non-ionic counterparts. In addition, we propose that aggregation in the ionic liquid has a significant impact on the entropy of mixing, typically a strong driving force for miscibility in polymer solutions. In this talk we explain how each of these features serves to drive the critical composition to the middle of the phase diagram.

Lipson, Jane; White, Ronald

2013-03-01

152

Quantum Molecular Dynamics Simulation of Hypergolic Reactions Between an Energetic Ionic Liquid and Nitric Acid.  

National Technical Information Service (NTIS)

Recently, Energetic Ionic Liquids (EILs) have emerged as potential alternative hypergolic propellants to replace toxic monomethyl hydrazine (MMH). Ionic liquids have no appreciable vapor pressures, are safe to handle and can be tailored to have desired pr...

D. Sengupta J. V. Cole

2010-01-01

153

Photo-excitation dynamics of malachite green in ionic liquids studied by the transient grating method  

NASA Astrophysics Data System (ADS)

Photo-excitation dynamics of malachite green in ionic liquids has been studied by the transient grating method. Anomalies of the S1 lifetime and vibrational energy relaxation are found together with the structural relaxation of ionic liquid.

Fukuda, Masanori; Kajimoto, Okitsugu; Terazima, Masahide; Kimura, Yoshifumi

154

Molecular simulations of phosphonium-based ionic liquid  

Microsoft Academic Search

Compared with imidazolium-based ionic liquids (ILs), phosphonium-based ILs have been proven to be more stable in thermodynamics and less expensive to manufacture. In this work, a kind of phosphonium-based IL, [PC6C6C6C14][Tf2N], was studied under several conditions using molecular dynamics simulations based on both the all-atom force field (AAFF) and the united-atom force field. Liquid density was calculated to validate the

Xiaomin Liu; Guohui Zhou; Suojiang Zhang; Guangren Yu

2010-01-01

155

Nano-segregation in ionic liquids: scorpions and vanishing chains.  

PubMed

The present study analyses the large structural differences, first observed using X-ray diffraction, between 1-alkyl-3-methylimidazolium-based ionic liquids, [Cnmim][Ntf2] (n = 3, 6, 9), and their counterparts with ether-substituted alkyl side chains, [(C1OC1)(n/3)mim][Ntf2] (n = 3, 6, 9). The MD simulations-obtained using a non-polarizable atomistic force-field to model the ionic liquids under discussion-demonstrate that the suppression of the nanostructured nature in the ionic liquids with ether chains is persistent along the entire series and it is not due to any modification of the polar network of the ionic liquid but rather due to the different morphologies of the non-polar regions that surround it. The modification of the non-polar regions-shift from bulky segregated domains in [Cnmim][Ntf2] to thin enveloping ones in [(C1OC1)(n/3)mim][Ntf2]-are caused by the inability of the oxygen-substituted alkyl side chains to pack effectively side by side, the existence of kinks along the chain that lead eventually to intra-molecular, scorpion-like interactions between the chains and the imidazolium ring, and by their stronger interactions with the cations of the polar network via the lone electron pairs of the ether oxygen atoms. PMID:23999599

Shimizu, Karina; Bernardes, Carlos E S; Triolo, Alessandro; Canongia Lopes, José N

2013-09-02

156

EVALUATING THE GREENNESS OF IONIC LIQUIDS VIA LIFE CYCLE ASSESSMENT  

EPA Science Inventory

Ionic Liquids have been suggested as "greener" replacements to traditional solvents. However, the environmental impacts of the life cycle phases have not been studied. Such a "cradle to gate" Life Cycle Assessment (LCA) for comparing the environmental impact of various solvents...

157

Ionic liquid-mediated extraction of lipids from algal biomass  

Microsoft Academic Search

Lipids from algal biomass were extracted using mixtures of ionic liquids (ILs) and methanol, and fatty acid profiles of the extracted lipids were characterized in this work. Mixtures of ILs and methanol successfully dissolved biomass leaving lipids insoluble. The total contents of lipids extracted from commercial and cultivated Chlorella vulgaris were 10.6% and 11.1%, respectively, by the conventional Bligh and

Young-Hoo Kim; Yong-Keun Choi; Seongmin Lee; Yung-Hun Yang; Hyung Joo Kim; Tae-Joon Park; Yong Hwan Kim; Sang Hyun Lee

158

Solubility of monosaccharides in ionic liquids – Experimental data and modeling  

Microsoft Academic Search

Biomass represents nowadays one of the more sustainable alternatives as a source of fuels and chemicals. The capability of ionic liquids to act as selective solvents and catalysts for biomass processing has already been proven. Thus they are a serious alternative to conventional solvents, provided that phase equilibria with biomass derived compounds is studied. To overcome the lack of experimental

Aristides P. Carneiro; Oscar Rodríguez; Eugénia A. Macedo

159

EXPEDITIOUS SOLVENT-FREE PREPARATION OF IONIC LIQUIDS USING MICROWAVES  

EPA Science Inventory

Ambient temperature ionic liquids comprising 1,3-dialkylimidazolium cations have shown great promise as alternative solvents in view of their negligible vapor pressure, ease of handling and potential for recycling. An efficient solventless protocol for the preparation of a wide v...

160

POTENTIAL APPLICATIONS OF IONIC LIQUIDS IN WOOD RELATED INDUSTRIES  

Microsoft Academic Search

The use of ionic liquids (ILs) has provided a new platform for efficient utilization of wood. In this paper, applications of ILs in wood-related industries are reviewed. First, the dissolution of wood in ILs and its application are described. Then the ILs used for wood preservation and improvement of wood anti-electrostatic and fire-proof properties are illustrated. Finally, \\

Shaoqin Han; Jialin Li; Shengdong Zhu; Rui Chen; Yuanxin Wu; Xinya Zhang; Ziniu Yu

161

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns  

Microsoft Academic Search

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis,

Wishart

2008-01-01

162

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns  

Microsoft Academic Search

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs generally have low volatilities and are combustion-resistant, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in

Wishart

2011-01-01

163

High performance batteries with carbon nanomaterials and ionic liquids  

SciTech Connect

The present invention is directed to lithium-ion batteries in general and more particularly to lithium-ion batteries based on aligned graphene ribbon anodes, V.sub.2O.sub.5 graphene ribbon composite cathodes, and ionic liquid electrolytes. The lithium-ion batteries have excellent performance metrics of cell voltages, energy densities, and power densities.

Lu, Wen (Littleton, CO)

2012-08-07

164

The third evolution of ionic liquids: active pharmaceutical ingredients  

Microsoft Academic Search

A modular, ionic liquid (IL)-based strategy allows compartmentalized molecular level design of a wide range of new materials with tunable biological, as well as the well known physical and chemical, properties of ILs, which thus deserve consideration as 'tunable' active pharmaceutical ingredients (APIs) with novel performance enhancement and delivery options. IL strategies can take advantage of the dual nature (discrete

Whitney L. Hough; Richard P. Swatloski; Scott K. Spear; Daniel T. Daly; Juliusz Pernak; Judith E. Grisel; Richard D. Carliss; Morgan D. Soutullo; James H. Davis; Robin D. Rogers

2007-01-01

165

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

166

Ionic liquid synthesis in a microstructured reactor for process intensification  

Microsoft Academic Search

Ionic liquids (IL) are the focus of growing interest over the last few years due to their low vapour pressure being beneficial for replacing common organic solvents with high vapour pressure. IL synthesised via alkylation are produced in batch or semi-batch stirred tank reactors. The reaction is highly exothermic and the kinetics was shown to be fast. The heat management

A. Renken; V. Hessel; P. Löb; R. Miszczuk; M. Uerdingen; L. Kiwi-Minsker

2007-01-01

167

Phase Behavior of Block Copolymer Solutions in an Ionic Liquid  

NASA Astrophysics Data System (ADS)

Incorporation of ionic liquids into block copolymers is of interest for applications such as high temperature fuel cell membranes. We investigate the lyotropic and thermotropic phase behavior of solutions of poly(styrene-b-2-vinyl pyridine) (S2VP) block copolymers in an ionic liquid consisting of imidazole and bis(trifluoromethane)sulfonamide (HTFSI). Using small angle X-ray scattering (SAXS) and static birefringence, we demonstrate that the ionic liquid behaves as a selective solvent, preferentially solvating the poly(2-vinyl pyridine) segment of the block copolymer. At moderate to high concentrations (>= 40 wt%) of copolymer, we observe lyotropic phase transitions to lamellar and cylindrical (hcp) nanostructures. At low concentrations of S2VP copolymer (<= 30 wt%), we observe poorly-ordered, microphase-separated structures, which do not resemble the face-centered cubic or body-centered cubic spherical micelles observed in block copolymer solutions in molecular solvents. We observe that the order-disorder transition temperature of the series of SVP copolymers does not depend strongly on the concentration of the block copolymer solution in ionic liquid.

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

2009-03-01

168

Unexpected Preferential Dehydration of Artemisinin in Ionic Liquids  

NASA Astrophysics Data System (ADS)

Thermodynamic measurements (at 298 K) reveal that a crucial step in the extraction process of the key antimalarial drug artemisinin by ionic liquids (ILs), namely, precipitation through the addition of water, is driven by artemisinin dehydration due to the differences in the water's interaction with the bulk ILs, rather than with the artemisinin itself.

Sanders, Marc W.; Wright, Lawrence; Tate, Lauren; Fairless, Gayle; Crowhurst, Lorna; Bruce, Neil C.; Walker, Adam J.; Hembury, Guy A.; Shimizu, Seishi

2009-09-01

169

Synthesis of ionic liquid templated zeolite like structures  

Microsoft Academic Search

This study describes the utilization of the alkyl substituted imidazolium based ionic liquid as a structure directing agent of the MFI type zeolite structure in water rich environment. The resulted zeolite like structure presents some similarities with the parent MFI structure, but grows preferentially in 1D leading to zeolite like nanofibers.

Amando Martín; Svetlana Ivanova; Francisca Romero Sarria; Miguel Ángel Centeno; Jose Antonio Odriozola

2010-01-01

170

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

171

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

172

Synthesis of dioctyl phthalate using acid functionalized ionic liquid as catalyst  

Microsoft Academic Search

Dioctyl phthalate were synthesized by using acid functionalized ionic liquid as catalyst. The results indicated that HSO3-functionalized Brønsted acidic ionic liquids show better catalytic and reusable performance than non-functionalized ionic liquids or the combination of neutral ionic liquids and Brønsted acid. Under the optimum conditions, using 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogen sulfate as catalyst, the conversion of phthalic anhydride was 98%. After easily

Hongliang Li; Shitao Yu; Fusheng Liu; Congxia Xie; Lu Li

2007-01-01

173

Ionic liquid pretreatment of cellulosic biomass: enzymatic hydrolysis and ionic liquid recycle.  

PubMed

Ionic liquids (ILs) are promising solvents for the pretreatment of biomass as certain ILs are able to completely solubilize lignocellulose. The cellulose can readily be precipitated with an anti-solvent for further hydrolysis to glucose, but the anti-solvent must be removed for the IL to be recovered and recycled. We describe the use of aqueous kosmotropic salt solutions to form a three-phase system that precipitates the biomass, forming IL-rich and salt-rich phases. The phase behavior of [Emim][Ac] and aqueous phosphate salt systems is presented, together with a process for recycling the [Emim][Ac] and enzymatically hydrolyzing the cellulose. This process reduces the amount of water to be evaporated from recycled IL, permitting efficient recycle of the IL. Material balances on the process, with multiple recycles of the [Emim][Ac], quantify the major components from a Miscanthus feedstock through the pretreatment, separation, and enzymatic hydrolysis steps. A more rapid and higher yielding conversion of cellulose to glucose is obtained by use of the three-phase system as compared to the cellulose obtained from biomass pretreated with IL and precipitated with water. The addition of a kosmotropic salt during the precipitation results in partial delignification of the biomass, which makes the substrate more accessible, enhancing the enzymatic hydrolysis. PMID:21246505

Shill, Kierston; Padmanabhan, Sasisanker; Xin, Qin; Prausnitz, John M; Clark, Douglas S; Blanch, Harvey W

2010-12-22

174

On the electrodeposition of titanium in ionic liquids.  

PubMed

The ability to electrodeposit titanium at low temperatures would be an important breakthrough for making corrosion resistant layers on a variety of technically important materials. Ionic liquids have often been considered as suitable solvents for the electrodeposition of titanium. In the present paper we have extensively investigated whether titanium can be electrodeposited from its halides (TiCl(4), TiF(4), TiI(4)) in different ionic liquids, namely1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide ([BMP]Tf(2)N), and trihexyltetradecyl-phosphonium bis(trifluoromethylsulfonyl)amide ([P(14,6,6,6)]Tf(2)N). Cyclic voltammetry and EQCM measurements show that, instead of elemental Ti, only non-stoichiometric halides are formed, for example with average stoichiometries of TiCl(0.2), TiCl(0.5) and TiCl(1.1). In situ STM measurements show that-in the best case-an ultrathin layer of Ti or TiCl(x) with thickness below 1 nm can be obtained. In addition, results from both electrochemical and chemical reduction experiments of TiCl(4) in a number of these ionic liquids support the formation of insoluble titanium cation-chloride complex species often involving the solvent. Solubility studies suggest that TiCl(3) and, particularly, TiCl(2) have very limited solubility in these Tf(2)N based ionic liquids. Therefore it does not appear possible to reduce Ti(4+) completely to the metal in the presence of chloride. Successful deposition processing for titanium in ionic liquids will require different maybe tailor-made titanium precursors that avoid these problems. PMID:18404225

Endres, F; Zein El Abedin, S; Saad, A Y; Moustafa, E M; Borissenko, N; Price, W E; Wallace, G G; MacFarlane, D R; Newman, P J; Bund, A

2008-02-27

175

A NEW CLASS OF SOLVENTS FOR TRU DISSOLUTION AND SEPARATION: IONIC LIQUIDS  

EPA Science Inventory

This report focuses on the progress of a study of a New Class of Solvents for TRU Dissolution and Separation: Ionic Liquids. Key research issues are: (1) examining Cs, Sr, Tc, and TRU partitioning in Ionic Liquid/aqueous systems; (2) developing new Ionic Liquids for TRU separat...

176

Analysis and Prediction of Dual-Mode Chemical and Electric Ionic Liquid Propulsion Performance  

Microsoft Academic Search

An analytical and numerical investigation of the performance of a dual -mode propulsion system using ionic liquids is presented . Chemical bi-propellant performance of select propellants is determined using Chemical Equilibrium with Applications. Comparison of predicted specific impulse of ionic liquid s with hydrazine and UDMH show that the ionic liquid propellants have 3-12% lower specific impulse when paired with

Brian R. Donius; Joshua L. Rovey

177

Solvent extraction of rare-earth ions based on functionalized ionic liquids  

SciTech Connect

We herein report the achievement of enhanced extractabilities and selectivities for separation of rare earth elements based on functionalized ionic liquids. This work highlights the potential of developing a comprehensive ionic liquid-based extraction strategy for rare earth elements using ionic liquids as both extractant and diluent.

Sun, Xiaoqi [ORNL; Dai, Sheng [ORNL; Luo, Huimin [ORNL

2012-01-01

178

An efficient regioselective NBS aromatic bromination in the presence of an ionic liquid  

Microsoft Academic Search

A simple, efficient, and rapid method was developed for high-yielding regioselective monobromination of activated aromatic compounds using NBS in combination with ionic liquid 1-butyl-1-methylimidazolium bromide ([Bmim]Br) or dioxane. The ionic liquid is recyclable and can be reused with minimal loss in the catalytic efficiency if the ionic liquid is rapidly microwaved prior to reactions.

Subramanya R. K. Pingali; Monika Madhav; Branko S. Jursic

2010-01-01

179

Organic solvent nanofiltration in asymmetric hydrogenation: enhancement of enantioselectivity and catalyst stability by ionic liquids.  

PubMed

This communication describes the enhancement of the enantioselectivity and the stability of Ru-BINAP with the ionic liquid trihexyl(tetradecyl)phosphonium chloride (CyPhos101), and the use of organic solvent nanofiltration for the efficient separation of the catalyst and ionic liquid from the hydrogenation product, followed by simultaneous recycling of the catalyst and ionic liquid. PMID:16767276

Wong, Hau-To; See-Toh, Yoong Hsiang; Ferreira, Frederico Castelo; Crook, Robert; Livingston, Andrew G

2006-04-11

180

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

181

Ionic galleries: a bilayered host-guest cocrystal of C-propyl pyrogallol[4]arene with an ionic liquid.  

PubMed

We report on a cocrystal between C-propyl pyrogallol[4]arene and the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate exhibiting a remarkable bilayer topology comprising two unique host-guest complexes resulting from the ionic liquid cation binding in two distinctive orientations relative to the macrocycle. PMID:22531153

Fowler, Drew A; Teat, Simon J; Baker, Gary A; Atwood, Jerry L

2012-04-24

182

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

183

An overview of the mutual solubilities of water–imidazolium-based ionic liquids systems  

Microsoft Academic Search

Ionic liquids (ILs) are a novel class of chemical compounds with interesting properties that are driving a lot of research in several fields. For ionic liquids to be effectively used as solvents in liquid–liquid extractions, the knowledge of the mutual solubilities between ILs and the second liquid phase is fundamental. Furthermore, while ILs cannot volatilise and lead to air pollution,

Mara G. Freire; Luís M. N. B. F. Santos; Ana M. Fernandes; João A. P. Coutinho; Isabel M. Marrucho

2007-01-01

184

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

185

Effects of Extrinsic and Intrinsic Proton Activity on The Mechanism of Oxygen Reduction in Ionic Liquids  

NASA Astrophysics Data System (ADS)

Mechanisms for oxygen reduction are proposed for three distinct cases covering two ionic liquids of fundamentally different archetypes and almost thirty orders of magnitude of proton activity. Proton activity is treated both extrinsically by varying the concentration and intrinsically by selecting proton donors with a wide range of aqueous pKa values. The mechanism of oxygen reduction in ionic liquids is introduced by way of the protic ionic liquid (pIL) triethylammonium triflate (TEATf) which shares some similarities with aqueous acid solutions. Oxygen reduction in TEATf begins as the one electron rate limited step to form superoxide, O2 *-, which is then rapidly protonated by the pIL cation forming the perhydroxyl radical, HO2*. The perhydroxyl radical is further reduced to peroxidate (HO2-) and hydrogen peroxide in proportions in accordance with their pKa. The reaction does not proceed beyond this point due to the adsorption of the conjugate base triethylammine interfering with the disproportionation of hydrogen peroxide. This work demonstrates that this mechanism is consistent across Pt, Au, Pd, and Ag electrodes. Two related sets of experiments were performed in the inherently aprotic ionic liquid 1-butyl-2,3-dimethylimidazolium triflate (C4dMImTf). The first involved the titration of acidic species of varying aqueous pKa into the IL while monitoring the extent of oxygen reduction as a function of pKa and potential on Pt and glassy carbon (GC) electrodes. These experiments confirmed the greater propensity of Pt to reduce oxygen by its immediate and abrupt transition from one electron reduction to four electron reduction, while oxygen reduction on GC gradually approaches four electron reduction as the potentials were driven more cathodic. The potential at which oxygen reduction initiates shows general agreement with the Nernst equation and the acid's tabulated aqueous pKa value, however at the extremely acidic end, a small deviation is observed. The second set of experiments in C4dMImTf solicited water as the proton donor for oxygen reduction in an approximation of the aqueous alkaline case. The water content was varied between extremely dry (<0.1 mol% H2O) and saturated (approximately 15.8 mol% H2O). As the water content increased so too did the extent of oxygen reduction eventually approach two electrons on both Pt and GC. However, additional water led to a linear increase in the Tafel slope under enhanced mass transport conditions up to the point of 10 mol% water. This inhibition of oxygen adsorption is the result of the interaction between superoxide and water and more specifically is proposed to be associated with decomposition of theC4dMIm + cation by hydroxide at the elevated temperatures required for the experiment. Oxygen reduction on both Pt and GC follows Nernstian behavior as the water content is increased. Separate mechanisms for oxygen reduction on Pt and GC are proposed based on the nature of the Nernstian response in these systems.

Zeller, Robert August

186

Ionic Conduction and Electronic Properties in Liquid In Se System  

NASA Astrophysics Data System (ADS)

Electronic and ionic conductivities and thermoelectric power of liquid In1-x Sex system have been measured as a function of concentration and temperature. The electronic conductivity in the system shows a deep minimum near the Se composition x=0.58 and the ionic conductivity has a broad maximum at this composition, where the thermoelectric power shows a large negative maximum. The electronic conductivity and thermoelectric power were analyzed in terms of the Fermi-Dirac integrals. It is found that the shape of the density of state, N(E), changes gradually with concentration.

Itoh, Keiji; Usuki, Takesi; Tamaki, Shigeru

1998-07-01

187

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

188

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns  

SciTech Connect

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. We and our collaborators (R. Engel (Queens College, CUNY) and S. Lall-Ramnarine, (Queensborough CC, CUNY)) develop and characterize new ionic liquids specifically designed for our radiolysis and solvation dynamics studies. IL solvation and rotational dynamics are measured by TCSPC and fluorescence upconversion measurements in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy. Diffusion rates are obtained by PGSE NMR in S. Greenbaum's lab at Hunter College, CUNY and S. Chung's lab at William Patterson U. Professor Mark Kobrak of CUNY Brooklyn College performs molecular dynamics simulations of solvation processes. A collaboration with M. Dietz at U. Wisc. Milwaukee is centered around the properties and radiolytic behavior of ionic liquids for nuclear separations. Collaborations with C. Reed (UC Riverside), D. Gabel (U. Bremen) and J. Davis (U. South Alabama) are aimed at characterizing the radiolytic and other properties of borated ionic liquids, which could be used to make fissile material separations processes inherently safe from criticality accidents.

Wishart,J.F.

2008-09-29

189

Determination of four heterocyclic insecticides by ionic liquid dispersive liquid-liquid microextraction in water samples.  

PubMed

A novel microextraction method termed ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) combining high-performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of insecticides in water samples. Four heterocyclic insecticides (fipronil, chlorfenapyr, buprofezin, and hexythiazox) were selected as the model compounds for validating this new method. This technique combines extraction and concentration of the analytes into one step, and the ionic liquid was used instead of a volatile organic solvent as the extraction solvent. Several important parameters influencing the IL-DLLME extraction efficiency such as the volume of extraction solvent, the type and volume of disperser solvent, extraction time, centrifugation time, salt effect as well as acid addition were investigated. Under the optimized conditions, good enrichment factors (209-276) and accepted recoveries (79-110%) were obtained for the extraction of the target analytes in water samples. The calibration curves were linear with correlation coefficient ranged from 0.9947 to 0.9973 in the concentration level of 2-100 microg/L, and the relative standard deviations (RSDs, n=5) were 4.5-10.7%. The limits of detection for the four insecticides were 0.53-1.28 microg/L at a signal-to-noise ratio (S/N) of 3. PMID:19118833

Liu, Yu; Zhao, Ercheng; Zhu, Wentao; Gao, Haixiang; Zhou, Zhiqiang

2008-12-03

190

SPECTROSCOPIC STUDIES OF STRUCTURE, DYNAMICS AND REACTIVITY IN IONIC LIQUIDS.  

SciTech Connect

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) [1] are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. IL solvation and rotational dynamics are measured by TCSPC in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy.

WISHART,J.F.

2007-11-30

191

Nanostructured liquid crystals combining ionic and electronic functions.  

PubMed

New molecular materials combining ionic and electronic functions have been prepared by using liquid crystals consisting of terthiophene-based mesogens and terminal imidazolium groups. These liquid crystals show thermotropic smectic A phases. Nanosegregation of the pi-conjugated mesogens and the ionic imidazolium moieties leads to the formation of layered liquid-crystalline (LC) structures consisting of 2D alternating pathways for electronic charges and ionic species. These nanostructured materials act as efficient electrochromic redox systems that exhibit coupled electrochemical reduction and oxidation in the ordered bulk states. For example, compound 1 having the terthienylphenylcyanoethylene mesogen and the imidazolium triflate moiety forms the smectic LC nanostructure. Distinct reversible electrochromic responses are observed for compound 1 without additional electrolyte solution on the application of double-potential steps between 0 and 2.5 V in the smectic A phase at 160 degrees C. In contrast, compound 2 having a tetrafluorophenylterthiophene moiety and compound 3 having a phenylterthiophene moiety exhibit irreversible cathodic reduction and reversible anodic oxidation in the smectic A phases. The use of poly(3,4-ethylenedioxythiophene)-poly(4-styrene sulfonate) (PEDOT-PSS) as an electron-accepting layer on the cathode leads to the distinct electrochromic responses for 2 and 3. These results show that new self-organized molecular redox systems can be built by nanosegregated pi-conjugated liquid crystals containing imidazolium moieties with and without electroactive thin layers on the electrodes. PMID:20465261

Yazaki, Sanami; Funahashi, Masahiro; Kagimoto, Junko; Ohno, Hiroyuki; Kato, Takashi

2010-06-01

192

Thermo-Rheometric Studies of New Class Ionic Liquid Lubricants  

NASA Astrophysics Data System (ADS)

Due to their specific properties, such as small volatility, nonflammability, extreme thermal stability, low melting point, wide liquid range, and good miscibility with organic materials, ionic liquids attracted particular interest in various industrial processes. Recently, the unique properties of ionic liquids caught the attention of space tribologists. The traditional lubricating materials used in space have limited lifetimes in vacuum due to the catalytic degradation on metal surfaces, high vaporization at high temperatures, dewetting, and other disadvantages. The lubricants for the space applications must have vacuum stability, high viscosity index, low creep tendency, good elastohydrodynamic and boundary lubrication properties, radiation atomic oxygen resistance, optical or infrared transparency. Unfortunately, the properties such as heat flow, heat capacity, thermogravimetric weight loss, and non-linearity in the rheological behavior of the lubricants are not studied well for newly developed systems. These properties are crucial to analyzing thermodynamic and energy dissipative aspects of the lubrication process. In this paper we will present the rheological and heat and mass transfer measurements for the ionic liquid lubricants, their mixtures with and without additive.

Bakhtiyarov, Sayavur; Street, Kenneth; Scheiman, Daniel; van Dyke, Alan

2010-11-01

193

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

194

Protic pharmaceutical ionic liquids and solids: aspects of protonics.  

PubMed

A series of new protic compounds based on active pharmaceutical ingredients have been synthesised and characterised. Some of the salts synthesised produced ionic liquids, while others that were associated with rigid molecular structures tended to produce high melting points. The "protonic" behaviour of these compounds was found to be a major determinant of their properties. Indicator studies, FTIR-ATR and transport properties (Walden plot) were used to probe the extent of proton transfer and ion association in these ionic liquids. While proton transfer was shown to have taken place in all cases, the Walden plot indicated strong ion association in the primary amine based examples due to hydrogen bonding. This was further explored via crystal structures of related compounds, which showed that extended hydrogen bonded clusters tend to form in these salts. These clusters may dictate membrane transport properties of these compounds in vivo. PMID:22455028

Stoimenovski, Jelena; Dean, Pamela M; Izgorodina, Ekaterina I; MacFarlane, Douglas R

2012-01-01

195

Maillard reaction products from chitosan-xylan ionic liquid solution.  

PubMed

A facile method is reported to prepare Maillard reaction products (MRPs) from chitosan and xylan in co-solvent ionic liquid. UV absorbance and fluorescence changes were regarded as indicators of the occurrence of Maillard reaction. FT-IR, NMR, XRD and TG were used to investigate the structure of chitosan-xylan conjugate. The results revealed that when chitosan reacted with xylan in ionic liquid, the hydrogen bonds in chitosan were destroyed, the facts resulted in the formation of chitosan-xylan MRPs. Moreover, when the mass ratio of chitosan to xylan was 1:1, the Maillard reaction proceeded easily. In addition, relatively high antioxidant property was also noted for the chitosan-xylan conjugate with mass ratio 1:1. So the obtained chitosan-xylan MRP is a promising antioxidant agent for food industry. PMID:23987419

Luo, Yuqiong; Ling, Yunzhi; Wang, Xiaoying; Han, Yang; Zeng, Xianjie; Sun, Runcang

2013-06-28

196

IONIC LIQUIDS: RADIATION CHEMISTRY, SOLVATION DYNAMICS AND REACTIVITY PATTERNS.  

SciTech Connect

energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Methods. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. We and our collaborators (R. Engel (Queens College, CUNY) and S. Lall-Ramnarine, (Queensborough CC, CUNY)) develop and characterize new ionic liquids specifically designed for our radiolysis and solvation dynamics studies. IL solvation and rotational dynamics are measured by TCSPC and fluorescence upconversion measurements in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy. Diffusion rates are obtained by PGSE NMR in S. Greenbaum's lab at Hunter College, CUNY and S. Chung's lab at William Patterson U. Professor Mark Kobrak of CUNY Brooklyn College performs molecular dynamics simulations of solvation processes. A collaboration with M. Dietz and coworkers at ANL is centered around the properties and radiolytic behavior of ionic liquids for nuclear separations. Collaborations with C. Reed (UC Riverside), D. Gabel (U. Bremen) and J. Davis (U. South Alabama) are aimed at characterizing the radiolytic and other properties of borated ionic liquids, which could be used to make fissile material separations processes inherently safe from criticality accidents.

WISHART,J.F.

2007-10-01

197

High-frequency acoustic modes in an ionic liquid.  

PubMed

High-frequency collective dynamics of the ionic liquid 1-hexyl-3-methylimidazolium bromide, [C6C1im]Br, has been investigated by molecular dynamics simulations. Time correlation functions of mass current fluctuations were calculated for several wavevectors and the dispersion curves of excitations, ?(k), for longitudinal and transverse acoustic sound modes were obtained at different temperatures and pressures. Two different thermodynamic states have the same high-frequency sound velocity irrespective of the temperature provided that both have the same density. Partial time correlation functions of mass currents were calculated for the atoms belonging to the polar or the non-polar domains resulting from the heterogeneous structure of [C6C1im]Br. The partial correlation functions indicate that the polar domains are stiffer than the non-polar domains of the simulated ionic liquid. PMID:24070295

Ribeiro, Mauro C C

2013-09-21

198

High-frequency acoustic modes in an ionic liquid  

NASA Astrophysics Data System (ADS)

High-frequency collective dynamics of the ionic liquid 1-hexyl-3-methylimidazolium bromide, [C6C1im]Br, has been investigated by molecular dynamics simulations. Time correlation functions of mass current fluctuations were calculated for several wavevectors and the dispersion curves of excitations, ?(k), for longitudinal and transverse acoustic sound modes were obtained at different temperatures and pressures. Two different thermodynamic states have the same high-frequency sound velocity irrespective of the temperature provided that both have the same density. Partial time correlation functions of mass currents were calculated for the atoms belonging to the polar or the non-polar domains resulting from the heterogeneous structure of [C6C1im]Br. The partial correlation functions indicate that the polar domains are stiffer than the non-polar domains of the simulated ionic liquid.

Ribeiro, Mauro C. C.

2013-09-01

199

Multiple zeolite structures from one ionic liquid template.  

PubMed

This study reports the use of 1-butyl-3-methyl imidazolium methanesulfonate ionic liquid as a template in the synthesis of zeolites. It is found that the silicon source determines the formation of beta (BEA), mordenite framework inverted (MFI), or analcime (ANA) zeolites. Depending on this source, different preorganized complexes are obtained that drive the formation of the different zeolite structures. In the presence of ethanol, the ionic liquid form preorganized complexes that drive the formation of MFI. In its absence, BEA is obtained. Whereas, the large amount of sodium present when using sodium metasilicate leads to ANA formation. A molecular simulation study of the relative stability of the template-framework system and location of the template provides further insight into the mechanism of synthesis. PMID:23255393

Martínez Blanes, José María; Szyja, Bart?omiej M; Romero-Sarria, Francisca; Centeno, Miguel Ángel; Hensen, Emiel J M; Odriozola, José Antonio; Ivanova, Svetlana

2012-12-19

200

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

201

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

202

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

203

Catalytic Pauson–Khand reaction in ionic liquids  

Microsoft Academic Search

Ionic liquids (ILs) are suitable media for the Co2(CO)8-catalysed intramolecular and intermolecular Pauson–Khand (PK) annelation, provided that the reaction is carried out under a CO pressure of 10bar. Two diethyl allyl propargyl malonates were quantitatively converted into the relevant cyclopentenones, whereas heteroatom tethered enynes gave lower yields in their cyclocarbonylation products. A moderate yield in the corresponding Pauson–Khand product was

Piero Mastrorilli; Cosimo Francesco Nobile; Rossella Paolillo; Gian Paolo Suranna

2004-01-01

204

Regenerating cellulose from ionic liquids for an accelerated enzymatic hydrolysis  

Microsoft Academic Search

The efficient conversion of lignocellulosic materials into fuel ethanol has become a research priority in producing affordable and renewable energy. The pretreatment of lignocelluloses is known to be key to the fast enzymatic hydrolysis of cellulose. Recently, certain ionic liquids (ILs) were found capable of dissolving more than 10wt% cellulose. Preliminary investigations [Dadi, A.P., Varanasi, S., Schall, C.A., 2006. Enhancement

Hua Zhao; Cecil L. Jones; Gary A. Baker; Shuqian Xia; Olarongbe Olubajo; Vernecia N. Person

2009-01-01

205

Bi-ionic potentials across liquid anion exchanger membranes  

Microsoft Academic Search

Summary The bi-ionic potentials, B. I. P.'s, arising in cells of the type: A+L-c1| liquid anion exchanger membrane of extreme anionic selectivity| A+M-c1, are surveyed briefly but systematically. The membranes consisted of trioctyl-propyl ammonium salts dissolved ino-dichlorobenzene. As anticipated on the basis of previous theoretical and experimental work on porous membranes, the following regularities were observed. The B.I.P. arising with

Gerald Shean; Karl Sollner

1972-01-01

206

Characterization of cellulose fibers electrospun using ionic liquid  

Microsoft Academic Search

Nonwoven fibers of cellulose were obtained by electrospinning of cellulose in an ionic liquid, 1-butyl-3-methylinmidazolium\\u000a chloride (BMIMCl), which is known to be one of the non-volatile solvents. The electrospinning setup was modified in such a\\u000a way that the syringe was contained in a constant-temperature chamber because of the high melting point of BMIMCl, and the\\u000a electrospun fibers were collected on

Shi-Li Quan; Soon-Gon Kang; In-Joo Chin

2010-01-01

207

Kinetic study of ionic liquid synthesis in a microchannel reactor  

Microsoft Academic Search

A microchannel reaction system, mainly consisting of a micromixer and a tubular reactor, was used to investigate the kinetics of butylation of 1-methyl-imidazole [MIM] for the synthesis of the ionic liquid 1-butyl-3-methylimidazolium bromide ([BMIM]Br). The low variance (??2=0.019) of the residence time distribution, measured by a step stimuli–response tracer method, implies that this reaction system could be regarded as a

Shaozheng Hu; Anjie Wang; Holger Löwe; Xiang Li; Yao Wang; Changhong Li; Dong Yang

2010-01-01

208

MINOR ACTINIDE SEPARATIONS USING ION EXCHANGERS OR IONIC LIQUIDS  

SciTech Connect

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 chemical factors responsible for the selectivity of inorganic-based ion-exchange materials for actinide and lanthanide ions. Furthermore, we seek to determine whether ionic liquids can serve as the electrolyte that would enable formation of higher oxidation states of Am and other actinides. Experiments indicated that pH, presence of complexants and Am oxidation state exhibit significant influence on the uptake of actinides and lanthanides by layered sodium titanate and hybrid zirconium and tin phosphonate ion exchangers. The affinity of the ion exchangers increased with increasing pH. Greater selectivity among Ln(III) ions with sodium titanate materials occurs at a pH close to the isoelectric potential of the ion exchanger. The addition of DTPA decreased uptake of Am and Ln, whereas the addition of TPEN generally increases uptake of Am and Ln ions by sodium titanate. Testing confirmed two different methods for producing Am(IV) by oxidation of Am(III) in ionic liquids (ILs). Experimental results suggest that the unique coordination environment of ionic liquids inhibits the direct electrochemical oxidation of Am(III). The non-coordinating environment increases the oxidation potential to a higher value, while making it difficult to remove the inner coordination of water. Both confirmed cases of Am(IV) were from the in-situ formation of strong chemical oxidizers.

Hobbs, D.; Visser, A.; Bridges, N.

2011-09-20

209

Ruthenium-catalyzed olefin metathesis in ionic liquids.  

PubMed

[reaction--see text] Ionic liquid 1-butyl-3-methylimidazoliumhexafluorophosphate ([bmim]PF(6)) is described as an effective medium for ring-closing metathesis (RCM) using Grubbs catalysts. When [bmim]PF(6) was used as solvent, the RCM showed high conversions and a broad substrate tolerance. [bmim]PF(6) and the ruthenium catalyst were recycled after extraction of the product in the organic phase for at least three cycles. PMID:11700138

Buijsman, R C; van Vuuren, E; Sterrenburg, J G

2001-11-15

210

Noncorrosive ionic liquids composed of [HSO 4] as esterification catalysts  

Microsoft Academic Search

Seven Brønsted acidic ionic liquids (BAILs) composed of [HSO4] were prepared, characterized, and used as catalysts of low dosage in various esterification reactions. Pyridinium hydrogensulfate ([Hpy][HSO4]), 2-methylpyridine hydrogensulfate ([Hmpy][HSO4]), and 1-methylimidazole hydrogensulfate ([Hmim][HSO4]) are found to be nearly noncorrosive, whereas N-(4-sulfonic acid)butyl triethylammonium hydrogensulfate ([BSEt3N][HSO4]) corrodes 316L stainless steel heavily. It is illustrated that the acidity and hydrophilicity can be

Duan-Jian Tao; Xue-Ming Lu; Jian-Feng Lu; Kuan Huang; Zheng Zhou; You-Ting Wu

2011-01-01

211

Novel all-cellulose ecocomposites prepared in ionic liquids  

Microsoft Academic Search

In this study, a kind of novel all-cellulose ecocomposites based on cellulose and rice husk (RH) has been prepared by using\\u000a green solvent, ionic liquid (IL), as processing medium. Due to the presence of the RH, these ecocomposites also contain an\\u000a inorganic component, silica. The content and distribution of the silica in the ecocomposite have been investigated by energy\\u000a dispersive

Qiang Zhao; Richard C. M. Yam; Baoqing Zhang; Yingkui Yang; Xinjian Cheng; Robert K. Y. Li

2009-01-01

212

Photochemical oxidation of water and reduction of polyoxometalate anions at interfaces of water with ionic liquids or diethylether.  

PubMed

Photoreduction of [P(2)W(18)O(62)](6-), [S(2)Mo(18)O(62)](4-), and [S(2)W(18)O(62)](4-) polyoxometalate anions (POMs) and oxidation of water occurs when water-ionic liquid and water-diethylether interfaces are irradiated with white light (275-750 nm) or sunlight. The ionic liquids (ILs) employed were aprotic ([Bmim]X; Bmim = (1-butyl-3-methylimidazolium, X = BF(4), PF(6)) and protic (DEAS = diethanolamine hydrogen sulphate; DEAP = diethanolamine hydrogen phosphate). Photochemical formation of reduced POMs at both thermodynamically stable and unstable water-IL interfaces led to their initial diffusion into the aqueous phase and subsequent extraction into the IL phase. The mass transport was monitored visually by color change and by steady-state voltammetry at microelectrodes placed near the interface and in the bulk solution phases. However, no diffusion into the organic phase was observed when [P(2)W(18)O(62)](6-) was photo-reduced at the water-diethylether interface. In all cases, water acted as the electron donor to give the overall process: 4POM + 2H(2)O + h? ? 4POM(-) + 4H(+) + O(2). However, more highly reduced POM species are likely to be generated as intermediates. The rate of diffusion of photo-generated POM(-) was dependent on the initial concentration of oxidized POM and the viscosity of the IL (or mixed phase system produced in cases in which the interface is thermodynamically unstable). In the water-DEAS system, the evolution of dioxygen was monitored in situ in the aqueous phase by using a Clark-type oxygen sensor. Differences in the structures of bulk and interfacial water are implicated in the activation of water. An analogous series of reactions occurred upon irradiation of solid POM salts in the presence of water vapor. PMID:22753501

Bernardini, Gianluca; Wedd, Anthony G; Zhao, Chuan; Bond, Alan M

2012-07-02

213

Spontaneous vesicle formation with an ionic liquid amphiphile.  

PubMed

A simple and effective method for the formation of stable multilamellar vesicles is reported as a potential application of ionic liquid materials (IL's) and as replacements for conventional surfactants used in such applications. The methodology is based on the various approaches for the formation of vesicles from oppositely charged surfactants. Photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) have been used to estimate the size of the aggregates; the TEM studies have also revealed morphological differences in the self-assembled systems with changing ionic liquid material. Size measurements from PCS indicate consistent growth of the ionic-liquid containing vesicles with increasing concentration of added anionic surfactant. 2D NOESY NMR spectroscopy have been used to examine the manner in which IL amphiphile self-assembles with the second surfactant in solution. A comparison has been made between the aggregates formed from hexylpyridinium tetrafluoroborate ([HexPy][BF4-])/sodium dodecylsulfate (SDS) and hexylpyridinium bromide ([HexPy][Br])/sodium dodecylsulfate (SDS). PMID:19406415

Singh, Kulbir; Marangoni, D Gerrard; Quinn, Jason G; Singer, Robert D

2009-04-05

214

Understanding the impact of ionic liquid pretreatment on eucalyptus  

SciTech Connect

The development of cost-competitive biofuels necessitates the realization of advanced biomass pretreatment technologies. Ionic liquids provide a basis for one of the most promising pretreatment technologies and are known to allow effective processing of cellulose and some biomass species. Here, we demonstrate that the ionic liquid 1-ethyl-3-methyl imidazolium acetate, [C2mim][OAc], induces structural changes at the molecular level in the cell wall of Eucalyptus globulus. Deacetylation of xylan, acetylation of the lignin units, selective removal of guaiacyl units (increasing the syringyl:guaiacyl ratio) and decreased {beta}-ether content were the most prominent changes observed. Scanning electron microscopy images of the plant cell wall sections reveal extensive swelling during [C2mim][OAc] pretreatment. X-ray diffraction measurements indicate a change in cellulose crystal structure from cellulose I to cellulose II after [C2mim][OAc] pretreatment. Enzymatic saccharification of the pretreated material produced increased sugar yields and improved hydrolysis kinetics after [C2mim][OAc] pretreatment. These results provide new insight into the mechanism of ionic liquid pretreatment and reaffirm that this approach may be promising for the production of cellulosic biofuels from woody biomass.

Centikol, Ozgul [Joint Bioenergy Institute; Dibble, Dean [Joint Bioenergy Institute; Cheng, Gang [Joint Bioenergy Institute; Kent, Michael S [ORNL; Knierim, Manfred [Joint Bioenergy Institute; Melnichenko, Yuri B [ORNL

2010-01-01

215

Ultrasonication-assisted extraction and preconcentration of medicinal products from herb by ionic liquids  

Microsoft Academic Search

Ionic liquid-based extraction of medicinal or useful compounds from plants was investigated as an alternative to supercritical fluid, cloud point and conventional organic solvent extractions. The method integrated extraction and preconcentration. Medicinal products were first extracted by an ionic liquid solution, part of which was then converted to a hydrophobic form by anion metathesis for preconcentration. The remaining soluble ionic

Wentao Bi; Minglei Tian; Kyung Ho Row

2011-01-01

216

Preparation of AgX (X = Cl, I) nanoparticles using ionic liquids  

NASA Astrophysics Data System (ADS)

Nanoparticles of silver halides have been prepared by mixing silver halide powder with a single liquid phase consisting of an ionic liquid, isooctane, n-decanol and water. Much higher nanoparticle concentrations may be formed with ionic liquids using this new simple method than are found with conventionally applied surfactants. This method also emphasizes the applicability of ionic liquids as versatile components in microemulsions and as solvents for the synthesis of nanomaterials. The effect on the nanoparticles of changing the composition of the liquid mixtures and the nature of the ionic liquid is analysed. High nanoparticle concentrations were only found with chloride based ionic liquids, indicating the importance of the ionic liquid anion in the mechanism of the reaction.

Rodil, Eva; Aldous, Leigh; Hardacre, Christopher; Lagunas, M. Cristina

2008-03-01

217

Tetraalkylphosphonium polyoxometalate ionic liquids : novel, organic-inorganic hybrid materials.  

SciTech Connect

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 and viscosity comparable to those of the one previously described inorganic-organic POM-IL hybrid but with substantially improved thermal stability.

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

2007-01-01

218

Measurement and prediction of vapor–liquid equilibria of ternary systems containing ionic liquids  

Microsoft Academic Search

For the first time vapor–liquid equilibrium (VLE) data for ternary systems containing ionic liquids are reported. The data were measured by means of a computer-operated static VLE apparatus at 353.15K with the ionic liquids 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [EMIM]+[(CF3SO2)2N]? and 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [BMIM]+[(CF3SO2)2N]? and acetone, 2-propanol and water. The experimental VLE data of the binary systems were correlated using the Wilson, NRTL

Michael Döker; Jürgen Gmehling

2005-01-01

219

Dynamic effects in thin liquid films containing ionic surfactants  

NASA Astrophysics Data System (ADS)

This paper is dedicated to studying dynamic effects in thin liquid films (TLF) containing ionic surfactants. The standard theory of TLF drainage has been developed without considering the electrical double layer (EDL) in the hydrodynamic equations, although EDL always exists. In addition, it has been found that this theory very well describes the drainage of TLF containing non-ionic surfactants in the presence of electrolytes. The inclusion of EDL into the hydrodynamics of TLF complicates the theory, producing additional dynamic effects during film drainage. For example, a gradient of electrostatic disjoining pressure across the film arises, thus causing non-uniform electrostatic repulsion between the film surfaces. This paper analyzes the hydrodynamics of TLF with EDL. A new equation of drainage was derived. This equation accounts for the non-uniform distribution of surface charges during the films drainage, which is coupled with non-uniform electrostatic repulsion between the film surfaces and results in faster film drainage. The theory was tested with drainage experiments on TLF with ionic surfactants. Foam films containing sodium dodecyl sulfate (SDS) in the presence and in the absence of added electrolyte were studied and the experimental data compared to the theoretical predictions. The experimental results, however, disagree with the theory. For example, the kinetic equation predicted faster film drainage for foam films at low ionic strength; at high ionic strength the theory tends to wReynolds drainagew. Inversely, the experiment exhibited slower drainage than predicted by the Reynolds equation in both cases of low and high ionic strengths. Numerical simulations yielded V/VRe<1. In addition, cases of wpositivew and wnegativew velocity of film surfaces were shown. Despite the sign of the velocity the dependence V/VRe<1 remained. The analysis showed similarity between the experimental data and the prediction of the Manev-Tsekov-Radoev (MTR) drainage model at R

Karakashev, S. I.; Tsekov, R.; Ivanova, D. S.

2010-03-01

220

Solvent properties of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid  

Microsoft Academic Search

1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) was synthesized and purified to be used as a ionic liquid solvent. Its physicochemical properties were studied. The ionic liquid\\/water (Pil\\/water) and ionic liquid\\/heptane (Pil\\/heptane) distribution coefficients of a set of 40 compounds with various functionalities, including organic acids, organic bases, amino acids, antioxidants, and neutral compounds, were measured using liquid chromatography. For ionizable compounds, the Pil\\/water

S. Carda-Broch; A. Berthod; D. W. Armstrong

2003-01-01

221

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

222

Reversible Electro-Optic Device Employing Aprotic Molten Salts And Method  

Microsoft Academic Search

A single-compartment reversible mirror device having a solution of aprotic molten salt, at least one soluble metal-containing species comprising metal capable of being electrodeposited, and at least one anodic compound capable of being oxidized was prepared. The aprotic molten salt is liquid at room temperature and includes lithium and\\/or quaternary ammonium cations, and anions selected from trifluoromethylsulfonate (CF.sub.3 SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide

Benjamin P. Warner; T. Mark McCleskey; Anthony K. Burrell; Simon B. Hall

2005-01-01

223

Imidazolium-Based Poly(ionic liquid)s as New Alternatives for CO2 Capture.  

PubMed

Solid imidazolium-based poly(ionic liquid)s with variable molecular weights that contain the poly[2-(1-butylimidazolium-3-yl)ethyl methacrylate] (BIEMA) cation and different counter anions were evaluated in terms of CO2 capture and compared with classical ionic liquids with similar counter anions. In addition to poly(ionic liquid)s with often-applied ions such as BF4 (-) , PF6 (-) , NTf2 (-) , trifluoromethanesulfonate (OTf(-) ) and Br(-) , for the first time [BIEMA][acetate] was synthesised, which revealed a remarkably high CO2 sorption performance that exceeded the poly(ionic liquid)s studied previously on average by a factor of four (12.46?mg?gPIL (-1) ). This study provides an understanding of the factors that affect CO2 sorption and a comparison of the CO2 capture efficiency with the frequently used sorbents. Moreover, all the studied sorbents were reusable if regenerated under carefully selected conditions and can be considered as suitable candidates for CO2 sorption. PMID:23881741

Privalova, Elena I; Karjalainen, Erno; Nurmi, Mari; Mäki-Arvela, Päivi; Eränen, Kari; Tenhu, Heikki; Murzin, Dmitry Yu; Mikkola, Jyri-Pekka

2013-07-23

224

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

225

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

226

Homogeneous Liquid-Liquid Extraction of Rare Earths with the Betaine-Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System.  

PubMed

Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature. PMID:24169434

Vander Hoogerstraete, Tom; Onghena, Bieke; Binnemans, Koen

2013-10-28

227

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

228

Polysiloxane ionic liquids as good solvents for ?-cyclodextrin-polydimethylsiloxane polyrotaxane structures  

PubMed Central

Summary An ionic liquid based on polydimethylsiloxane with imidazolium salt brushes was synthesized as a good solvent for ?-cyclodextrin-polydimethylsiloxane rotaxane. As expected the PDMS-Im/Br ionic liquid had a liquid-like non-Newtonian behavior with rheological parameters dependent on frequency and temperature. The addition of rotaxane to the ionic liquid strengthened the non-Newtonian character of the sample and a type of stable liquid-like network was formed due to the contribution of weak ionic interactions. The structure is stable in the 20 to 80 °C domain as proved by the oscillatory and rotational rheological tests.

Marangoci, Narcisa; Ardeleanu, Rodinel; Ursu, Laura; Ibanescu, Constanta; Danu, Maricel; Simionescu, Bogdan C

2012-01-01

229

Partition coefficients of organic compounds in new imidazolium based ionic liquids using inverse gas chromatography.  

PubMed

Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55K. The influence of gas-liquid and gas-solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model. PMID:19414174

Revelli, Anne-Laure; Mutelet, Fabrice; Jaubert, Jean-Noël

2009-04-09

230

Polysiloxane ionic liquids as good solvents for ?-cyclodextrin-polydimethylsiloxane polyrotaxane structures.  

PubMed

An ionic liquid based on polydimethylsiloxane with imidazolium salt brushes was synthesized as a good solvent for ?-cyclodextrin-polydimethylsiloxane rotaxane. As expected the PDMS-Im/Br ionic liquid had a liquid-like non-Newtonian behavior with rheological parameters dependent on frequency and temperature. The addition of rotaxane to the ionic liquid strengthened the non-Newtonian character of the sample and a type of stable liquid-like network was formed due to the contribution of weak ionic interactions. The structure is stable in the 20 to 80 °C domain as proved by the oscillatory and rotational rheological tests. PMID:23209493

Marangoci, Narcisa; Ardeleanu, Rodinel; Ursu, Laura; Ibanescu, Constanta; Danu, Maricel; Pinteala, Mariana; Simionescu, Bogdan C

2012-09-24

231

Computer simulations of ionic liquids at electrochemical interfaces.  

PubMed

Ionic liquids are widely used as electrolytes in electrochemical devices. In this context, many experimental and theoretical approaches have been recently developed for characterizing their interface with electrodes. In this perspective article, we review the most recent advances in the field of computer simulations (mainly molecular dynamics). A methodology for simulating electrodes at constant electrical potential is presented. Several types of electrode geometries have been investigated by many groups in order to model planar, corrugated and porous materials and we summarize the results obtained in terms of the structure of the liquids. This structure governs the quantity of charge which can be stored at the surface of the electrode for a given applied potential, which is the relevant quantity for the highly topical use of ionic liquids in supercapacitors (also known as electrochemical double-layer capacitors). A key feature, which was also shown by atomic force microscopy and surface force apparatus experiments, is the formation of a layered structure for all ionic liquids at the surface of planar electrodes. This organization cannot take place inside nanoporous electrodes, which results in a much better performance for the latter in supercapacitors. The agreement between simulations and electrochemical experiments remains qualitative only though, and we outline future directions which should enhance the predictive power of computer simulations. In the longer term, atomistic simulations will also be applied to the case of electron transfer reactions at the interface, enabling the application to a broader area of problems in electrochemistry, and the few recent works in this field are also commented upon. PMID:23985966

Merlet, Céline; Rotenberg, Benjamin; Madden, Paul A; Salanne, Mathieu

2013-08-28

232

Solubility of phosphonium ionic liquid in alcohols, benzene, and alkylbenzenes.  

PubMed

The (solid + liquid) phase equilibria and (liquid + liquid) phase equilibria of binary mixtures containing quaternary phosphonium salt-tetrabutylphosphonium methanesulfonate and alcohols or alkylbenzenes were investigated. The systems {[(CH(3)CH(2)CH(2)CH(2))4P][CH(3)SO(3)] + 1-butanol, or 1-hexanol, 1-octanol, 1-decanol, or 1-dodecanol} and {[(CH(3)CH(2)CH(2)CH(2))4P][CH(3)SO(3)] + benzene, or toluene, ethylbenzene, or propylbenzene} have been measured by a dynamic method at a wide range of temperatures from 220 to 386 K. Solid-liquid equilibria with immiscibility in the liquid phase were detected with the aromatic hydrocarbons ethylbenzene and propylbenzene. The basic thermodynamic properties of pure ionic liquid--the melting point, enthalpy of fusion, enthalpy of solid-solid-phase transition, and glass transition--have been determined by differential scanning calorimetry. The experimental data of systems with alcohols were correlated by means of the UNIQUAC ASM and NRTL1 equations and of systems with alkylbenzenes with Wilson and NRTL equations utilizing parameters derived from the (solid + liquid) equilibrium. The root-mean-square deviations of the solubility temperatures for all calculated data are dependent upon the particular system and the particular equation used. PMID:17391024

Doma?ska, Urszula; Casás, Lidia M

2007-03-29

233

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

234

Ion shape effect on dynamics of ionic liquids  

NASA Astrophysics Data System (ADS)

Ionic liquids (ILs) are a group of salts composing of an organic cation and organic or inorganic anion with melting points below 100 ^oC and have many suitable properties, such as negligible vapor pressure, low flammability, high ionic conductivity and high thermal stability for various applications. Moreover, a great number of ILs with a variety of physical and chemical properties can be synthesized from a combination of different cations (most differently substituted imidazolium, pyridinium, and quaternary ammonium or phosphonium ions) and anions. One can judiciously select from a multitude of ILs to suit a specific application, where the concept of designer solvent comes from. To expedite the development process of target ILs, it is crucial to understand the relationship between ion shape and dynamics of ILs. We studied a wide range of ILs with different ion shape pairings and found the planar-planar paired ILs have a better dynamics as a whole.

Liu, Hongjun; Maginn, Edward

2012-02-01

235

Thermotropic liquid crystalline ionic stilbazoles and their miscible mixtures with non-ionic carbazolyl compounds  

Microsoft Academic Search

New thermotropic ionic liquid crystals were prepared from trans-4-nitro-4?-stilbazole and alkyl halides. trans-N-Alkyl-4-nitro-4?-stilbazolium bromides containing alkyl chains with 7 to 10 carbons and the chloride homologues containing alkyl chains with 5 to 10 carbons exhibited smectic phases. For example, trans-N-decyl-4-nitro-4?-stilbazolium bromide and trans-N-hexyl-4-nitro-4?-stilbazolium chloride showed smectic phases from 175 to 186°C and from 129 to 190°C, respectively. The temperature range

Yozo Kosaka; Takashi Kato; Toshiyuki Uryu

1995-01-01

236

Research Progress on Prediction Models for Physical Properties of Ionic Liquid  

NASA Astrophysics Data System (ADS)

The field of ionic liquid has gained rapid growth in recent years and occupied a forefront in green chemistry. As a useful instrument to the research and development of novel ionic liquids, the physical properties are of utmost importance. Thus, great efforts have been made to obtain these important data, as it is far from getting sufficient physiochemical information for intensive and extensive investigation which consequently becomes a bottleneck for the theoretical and applicable research of ionic liquids. Additionally, with the given immeasurable possible ionic liquids by various cation and anion combinations, it is an impossible task to find an ideal ionic liquid with desired physical properties using conventionally "try and error" process. For these reasons, exploration of novel prediction models for physical properties of ionic liquid is imperative. This paper gives an overview of recent progress of various prediction models.

Wang, Quan; Wu, Xiao Ming; Zhang, Da Yong

237

Ionic liquid batteries: Chemistry to replace alkaline\\/acid energy storage devices  

Microsoft Academic Search

Rather than depend on highly acidic or basic electrolytes, ionic liquids are used to create new types of solid state cells which mimic standard alkaline cells, but without the need for caustic electrolytes. Presented here is a non-aqueous approach to primary and secondary power sources, where the pure ionic liquid not only acts as the electrolyte\\/separator in both liquid and

Thomas E. Sutto; Teresa T. Duncan; Tiffany C. Wong; Karen McGrady

2011-01-01

238

Double-layer in ionic liquids: paradigm change?  

PubMed

Applications of ionic liquids at electrified interfaces to energy-storage systems, electrowetting devices, or nanojunction gating media cannot proceed without a deep understanding of the structure and properties of the interfacial double layer. This article provides a detailed critique of the present work on this problem. It promotes the point of view that future considerations of ionic liquids should be based on the modern statistical mechanics of dense Coulomb systems, or density-functional theory, rather than classical electrochemical theories which hinge on a dilute-solution approximation. The article will, however, contain more questions than answers. To trigger the discussion, it starts with a simplified original result. A new analytical formula is derived to rationalize the potential dependence of double-layer capacitance at a planar metal-ionic liquid interface. The theory behind it has a mean-field character, based on the Poisson-Boltzmann lattice-gas model, with a modification to account for the finite volume occupied by ions. When the volume of liquid excluded by the ions is taken to be zero (that is, if ions are extremely sparsely packed in the liquid), the expression reduces to the nonlinear Gouy-Chapman law, the canonical result typically used to describe the potential dependence of capacitance in electrochemical double layers. If ionic volume exclusion takes more realistic values, the formula shows that capacitance-potential curves for an ionic liquid may differ dramatically from the Gouy-Chapman law. Capacitance has a maximum close to the potential of zero charge, rather than the familiar minimum. At large potenials, capacitance decreases with the square root of potential, rather than increases exponentially. The reported formula does not take into account the specific adsorption of ions, which, if present, can complicate the analysis of experimental data. Since electrochemists use to think about the capacitance data in terms of the classical Gouy-Chapman theory, which, as we know, should be good only for electrolytes of moderate concentration, the question of which result is "better" arises. Experimental data are sparse, but a quick look at them suggests that the new formula seems to be closer to reality. Opinions here could, however, split. Indeed, a comparison with Monte Carlo simulations has shown that incorporation of restricted-volume effects in the mean-field theory of electrolyte solutions may give results that are worse than the simple Gouy-Chapman theory. Generally, should the simple mean-field theory work for such highly concentrated ionic systems, where the so-called ion-correlation effects must be strong? It may not, as it does not incorporate a possibility of charge-density oscillations. Somehow, to answer this question definitely, one should do further work. This could be based on density-functional theory (and possibly not on what is referred to as local density approximation but rather "weighted density approximation"), field theory methods for the account of fluctuations in the calculation of partition function, heuristic integral equation theory extended to the nonlinear response, systematic force-field computer simulations, and, most importantly, experiments with independently determined potentials of zero charge, as discussed in the paper. PMID:17469864

Kornyshev, Alexei A

2007-05-01

239

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

240

Design and Evaluation of Ionic Liquids as Novel CO2 Absorbents  

Microsoft Academic Search

This is the final report for project DE-FG26-04NT42122 'Design and Evaluation of Ionic Liquids as Novel CO Absorbents'. The objective of this 'breakthrough concepts' project was to investigate the feasibility of using ionic liquids for post-combustion CO capture and obtain a fundamental understanding of the solubility of CO and other components present in flue gas in ionic liquids. Our plan

Edward Maginn

2007-01-01

241

Novel alcamines ionic liquids based solvents: Preparation, characterization and applications in carbon dioxide capture  

Microsoft Academic Search

This work presents a study to apply ionic liquids as potential industrial solvents for carbon dioxide capture. In order to obtain effective and low cost ionic liquids solvents, novel alcamines ionic liquids of 2-aminoethanol tetrafluoroborate, 2-[2-hydroxyethyl (methyl) amino] ethanol tetrafluoroborate, 2-[2-hydroxyethyl (methyl) amino] ethanol phosphate, 2-[2-hydroxyethyl (methyl) amino] ethanol sulfate and 2-[2-hydroxyethyl (methyl) amino] ethanol chloride were synthesized and characterized.

Yansong Zhao; Xiangping Zhang; Yingpeng Zhen; Haifeng Dong; Guoying Zhao; Shaojuan Zeng; Xiao Tian; Suojiang Zhang

2011-01-01

242

High rate performance of a lithium polymer battery using a novel ionic liquid polymer composite  

Microsoft Academic Search

We present a new design of a lithium gel-polymer battery, fabricated with a (LILP) composite consisting of a lithium salt dissolved in an ionic liquid (binary Li-IL) and an ultra high molecular weight ionic liquid polymer (ILP). This polymer, with a Mw of over a million, was prepared by the bulk radical polymerization of a novel ionic liquid monomer, N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium

Takaya Sato; Shoko Marukane; Takuya Narutomi; Tadayoshi Akao

2007-01-01

243

Thermal, rheological, and ion-transport properties of phosphonium-based ionic liquids.  

PubMed

Phosphonium-based ionic liquids with varying counteranions from commercially available ionic liquid precursors enabled tunable viscosity, ionic conductivity, and thermal stability. Thermogravimetric analysis revealed a relationship between thermal stability and anion composition where anions with lower basicity remained stable to higher temperatures. Determination of glass transition temperatures and melting temperatures using differential scanning calorimetry revealed supercooling, crystallization, and dependence on anion composition. Rheological and ionic conductivity measurements determined the temperature-dependence of the viscosity and ionic conductivity of the phosphonium-based ionic liquids. Arrhenius analyses of conductivity and viscosity provided activation energies, which showed a decrease toward larger, more delocalized anions. An assessment according to the Walden plot displayed their efficacy relative to other ionic liquids. PMID:22026727

Green, Matthew D; Schreiner, Christian; Long, Timothy E

2011-11-09

244

Heterogeneous dynamics of ionic liquids from molecular dynamics simulations.  

PubMed

Molecular dynamics simulations have been performed to study the complex and heterogeneous dynamics of ions in ionic liquids. The dynamics of cations and anions in 1-ethyl-3-methyl imidazolium nitrate (EMIM-NO(3)) are characterized by van Hove functions and the corresponding intermediate scattering functions F(s)(k,t) and elucidated by the trajectories augmented by the use of singular spectrum analysis (SSA). Several time regions are found in the mean squared displacement of the ions. Change in the slope in a plot of the diffusion coefficient against temperature is found at around 410 K in the simulation. Heterogeneous dynamics with the presence of both localized ions and fast ions capable of successive jumps were observed at long time scales in the self-part of the van Hove functions and in the trajectories. Non-Gaussian dynamics are evidenced by the self-part of the van Hove functions and wave number dependence of F(s)(k,t) and characterized as Levy flights. Successive motion of some ions can continue even after several nanoseconds at 370 K, which is longer than the onset time of diffusive motion, t(dif). Structure of the long time dynamics of fast ions is clarified by the phase space plot of the successive motion using the denoised data by SSA. The continual dynamics are shown to have a long term memory, and therefore local structure is not enough to explain the heterogeneity. The motion connecting localized regions at about 370 K is jumplike, but there is no typical one due to local structural changes during jump motion. With the local motion, mutual diffusion between cation and anion occurs. On decreasing temperature, mutual diffusion is suppressed, which results in slowing down of the dynamics. This "mixing effect of cation and anion" is compared with the "mixed alkali effect" found in the ionics in the ionically conducting glasses, where the interception of paths by different alkali metal ions causes the large reduction in the dynamics [J. Habasaki and K. L. Ngai, Phys. Chem. Chem. Phys. 9, 4673 (2007), and references herein]. Although a similar mechanism of the slowing down is observed, strong coupling of the motion of cation and anion prevents complete interception unless deeply supercooled, and this explains the wide temperature region of the existence of the liquid and supercooled liquid states in the ionic liquid. PMID:19026060

Habasaki, J; Ngai, K L

2008-11-21

245

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

246

Redox chemistry of the Keggin heteropolyoxotungstate anion in ionic liquids  

Microsoft Academic Search

The solid salts of the 1-ethyl-3-methylimidazolium and the 1-n-pentyl-3-methylimidazolium cations, abbreviated [C2mim]+ and [C5mim]+, respectively, of the Keggin heteropolyanion, ?-[PW12O40]3?, were prepared. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements of both [Cnmim]3[?-PW12O40] salts (for n=2 and 5) were performed in acetonitrile containing either tetra-n-butylammonium hexafluorophosphate, abbreviated TBAPF6, or the corresponding [Cnmim]BF4 ionic liquids (ILs) as electrolytes. The results

Ming-Hsi Chiang; Julie A. Dzielawa; Mark L. Dietz; Mark R. Antonio

2004-01-01

247

Application of ionic liquids in organic pollutants control.  

PubMed

For their unique properties and good solubility for many different materials, ionic liquids (ILs) have been applied in several fields, such as separation process, synthesis, catalysis and electrochemistry. This paper focuses on applications of ILs in organic pollutants control. An overview of separation, recycling and control of organic pollutants with ILs is present, for example, phenolic compounds, polycyclic aromatic hydrocarbon (PAHs) and dyes from wastewater, dioxins from waste gas, polyamides from solid wastes, chlorophenothane (DDT) and dieldrin from contaminated soils. Furthermore, the problems and challenges of ILs in organic pollutants control are discussed. PMID:22343094

Ma, Jingying; Hong, Xiaoping

2012-02-14

248

Microrheological investigations in ionic liquids using optical trapping techniques.  

PubMed

In this paper, we demonstrate optical trapping of melamine particles (d ? 2.3 ?m) within the pure ionic liquid ethylammonium nitrate (EAN) and show the first microrheological investigations of these important compounds using this technique. By analyzing the power spectrum of a particle trapped in EAN, we monitor the variation in viscous drag that it experiences in proximity to the sample coverslip, showing excellent agreement with Faxén's law. We also demonstrate hydrodynamic coupling between pairs of trapped particles. Finally, we explore temperature-dependent viscosity changes in ??L samples of EAN as a further example of microrheological investigations of ILs. PMID:24001322

Dear, Richard D; Worrall, Emma K; Gault, William D; Ritchie, Grant A D

2013-09-04

249

Diffuse-charge dynamics of ionic liquids in electrochemical systems  

NASA Astrophysics Data System (ADS)

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.046102 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our simple scaling analysis suggests that the length scale ?D*lc* accurately characterizes the double-layer structure of ionic liquids with strong electrostatic correlations where lc* is the electrostatic correlation length (in contrast, the Debye screening length ?D* is the primary double-layer length for electrolytes) and the response time of ?D*3/2L*/(D*lc1/2) (not ?D*L*/D* that is the primary charging time of electrolytes) is the correct charging time scale of ionic liquids with strong electrostatic correlations where D* is the diffusivity and L* is the separation length of the cell. With these two new scales, data of both electric potential versus distance from the electrode and the total diffuse charge versus time collapse onto each individual master curve in the presence of strong electrostatic correlations. In addition, the dependance of the total diffuse charge on steric effects, short-range correlations, and driving voltages is thoroughly examined. The results from the asymptotic analysis are compared favorably with those from full numerical simulations. Finally, the absorption of excess salt by the double layer creates a depletion region outside the double layer. Such salt depletion may bring a correction to the leading order terms and break down the weakly nonlinear analysis. A criterion which justifies the weakly nonlinear analysis is verified with numerical simulations.

Zhao, Hui

2011-11-01

250

Significant Cation Effects in Carbon Dioxide-Ionic Liquid Systems  

PubMed Central

Carbon dioxide–ionic liquid systems are of great current interest, and significant efforts have been made lately to understand the intermolecular interactions in these systems. In general, all the experimental and theoretical studies have concluded so far that the main solute–solvent interaction takes effect through the anion, and the cation has no, or only a secondary role in solvation. In this theoretical approach it is shown that this view is unfounded, and evidence is provided that, similarly to the benzene–CO2 system, dispersion interactions are present between the solute and the cation. Therefore, this defines a novel site for tailoring solvents to tune CO2 solubility.

Holloczki, Oldamur; Kelemen, Zsolt; Konczol, Laszlo; Szieberth, Denes; Nyulaszi, Laszlo; Stark, Annegret; Kirchner, Barbara

2013-01-01

251

The Effect of Ionic Liquids on Protein Crystallization and X-ray Diffraction Resolution  

SciTech Connect

Ionic liquids exhibit a variety of properties that make them attractive solvents for biomaterials. Given the potential for productive interaction between ionic liquids and biological macromolecules, we investigated the use of ionic liquids as precipitating agents and additives for protein crystallization for six model proteins (lysozyme, catalase, myoglobin, trypsin, glucose isomerase, and xylanase). The ionic liquids produced changes in crystal morphology and mediated significant increases in crystal size in some cases. Crystals grown using ionic liquids as precipitating agents or as additives provided X-ray diffraction resolution similar to or better than that obtained without ionic liquids. Based upon the experiments performed with model proteins, the ionic liquids were used as additives for the crystallization of the poorly diffracting monoclonal antibody 106.3 Fab in complex with the B-type natriuretic peptide (5-13). The ionic liquids improved the crystallization behavior and provided improved diffraction resulting in the determination of the structure. Ionic liquids should be considered as useful additives for the crystallization of other proteins.

Judge, Russell A.; Takahashi, Sumiko; Longenecker, Kenton L.; Fry, Elizabeth H.; Abad-Zapatero, Cele; Chiu, Mark L.; (Abbott)

2009-09-08

252

High CO2 Solubility, Permeability and Selectivity in Ionic Liquids with the Tetracyanoborate Anion  

SciTech Connect

Five different ionic liquids containing the tetracyanoborate anion were synthesized and evaluated for CO2 separation performance. Measured CO2 solubility values were exceptionally high compared to analogous ionic liquids with different anions and ranged from 0.128 mol L-1 atm-1 to 0.148 mol L-1 atm-1. In addition, CO2 permeability and CO2/N2 selectivity values were measured using a supported ionic liquid membrane architecture and the separations performance of the ionic liquid membranes exceeded the Robeson upper bound. These results establish the distinct potential of the tetracyanoborate, [B(CN)4], anion for the separation of CO2.

Mahurin, Shannon Mark [ORNL; Hillesheim, Patrick C [ORNL; Yeary, Joshua S [ORNL; Jiang, Deen [ORNL; Dai, Sheng [ORNL

2012-01-01

253

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

254

Design and Evaluation of Ionic Liquids as Novel CO2 Absorbents  

SciTech Connect

This is the final report for project DE-FG26-04NT42122 'Design and Evaluation of Ionic Liquids as Novel CO{sub 2} Absorbents'. The objective of this 'breakthrough concepts' project was to investigate the feasibility of using ionic liquids for post-combustion CO{sub 2} capture and obtain a fundamental understanding of the solubility of CO{sub 2} and other components present in flue gas in ionic liquids. Our plan was to obtain information on how composition and structure of ionic liquid molecules affected solubility and other important physical properties via two major efforts: synthesis and experimental measurements and molecular simulation. We also planned to perform preliminary systems modeling study to assess the economic viability of a process based on ionic liquids. We accomplished all the milestones and tasks specified in the original proposal. Specifically, we carried out extensive quantum and classical atomistic-level simulations of a range of ionic liquids. These calculations provided detailed information on how the chemical composition of ionic liquids affects physical properties. We also learned important factors that govern CO{sub 2} solubility. Using this information, we synthesized or acquired 33 new ionic liquids. Many of these had never been made before. We carried out preliminary tests on all of these compounds, and more extensive tests on those that looked most promising for CO{sub 2} capture. We measured CO{sub 2} solubility in ten of these ionic liquids. Through our efforts, we developed an ionic liquid that has a CO{sub 2} solubility 2.6 times greater than the 'best' ionic liquid available to us at the start of the project. Moreover, we demonstrated that SO{sub 2} is also extremely soluble in ionic liquids, opening up the possibility of using ionic liquids to remove both SO{sub 2} and CO{sub 2} from flue gas. In collaboration with Trimeric Inc., a preliminary systems analysis was conducted and the results used to help identify physical properties that must be optimized to enable ionic liquids to be cost-competitive for CO{sub 2} capture. It was found that increasing the capacity of the ionic liquids for CO{sub 2} would be important, and that doing so could potentially make ionic liquids more effective than conventional amine solvents.

Edward Maginn

2007-07-15

255

Electrospraying insulating liquids via charged nanodrop injection from the Taylor cone of an ionic liquid  

NASA Astrophysics Data System (ADS)

Charge is injected into the bulk of an insulating liquid in the form of nanodrops produced by an immersed Taylor cone of an ionic liquid. The charge then drifts onto the insulator surface, destabilizing it and leading to the formation of an electrified jet that atomizes into approximately monodisperse micron size insulator drops. The approach is similar to those previously based on field injection of ions from sharp tungsten tips, but the continuous renewal and self-sharpening of the liquid charge-injector permits long-term stable operation. Using heptane as the insulator and 1-ethyl-3-methylimidazolium-BF4 as the ionic liquid we produce approximately monodisperse drops with average diameters ranging from less than 4 up to 20 ?m, injecting in some cases as little as 0.0002% by volume of ionic liquid. No fundamental limitation restricting the possibility of forming even smaller drops is apparent. The scaling law of Kim and Turnbull [``Generation of charged drops of insulating liquids by electrostatic spraying,'' J. Appl. Phys. 47, 1964 (1976)] where the drop diameter varies as the 2/3 power of the liquid flow rate and the -2/3 power of the spray current is confirmed, implying that the drops are on the average charged to 50%-60% of the Rayleigh limit.

Larriba-Andaluz, Carlos; Fernández de La Mora, Juan

2010-07-01

256

Activity coefficient models to describe isothermal vapor-liquid equilibrium of binary systems containing ionic liquids  

Microsoft Academic Search

Isothermal vapor-liquid equilibrium data of binary mixtures containing ionic liquids are correlated using three activity coefficient\\u000a models: UNIQUAC, Wilson, and NRTL. Twenty binary systems taken from the literature were selected for this study. A genetic\\u000a algorithm is used to determine the interaction parameters for the three models. The results given by the three models have\\u000a been compared with experimental data,

J. A. Lazzús; J. Marín

2010-01-01

257

Improving hydrothermal carbonization by using poly(ionic liquid)s.  

PubMed

Pores for thought: Porous nitrogen-doped carbon materials (HTC Carbon with PILs) composed of spherical nanoparticles, and also those with Au-Pd core-shell nanoparticles embedded (Au-Pd@N-Carbon) were synthesized. These materials can be prepared from sugars by hydrothermal carbonization (160-200 °C) in the presence of poly(ionic liquid)s (PILs), which act as a stabilizer, pore-generating agent, and nitrogen source. PMID:23592443

Zhang, Pengfei; Yuan, Jiayin; Fellinger, Tim-Patrick; Antonietti, Markus; Li, Haoran; Wang, Yong

2013-04-16

258

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

259

A computational approach to design energetic ionic liquids.  

PubMed

The present work deals with the theoretical estimation of ion-pair binding energies and the energetic properties of four ion pairs formed by combining the 1-butyl-2,4-dinitro-3-methyl imidazolium ion with nitrate (I), perchlorate (II), dinitramide (III), or 3,5-dinitro-1,2,4-triazolate (IV) anions. The counterpoise-corrected ion-pair binding energies were calculated for each ion pair at the B3LYP/6-311+G(d,p) level of theory. Results show that the cation-anion interaction is strongest for ion pair I and weakest for IV, indicating that the nitrate (I) has a greater tendency to exist as a stable ionic salt whereas the 3,5-dinitro-1,2,4-triazolate (IV) may exist as an ionic liquid. Natural bond orbital (NBO) analysis and electrostatic potential (ESP) mapping revealed that charge transfer occurs in all of the ion pairs, but is greatest (0.25e) for ion pair I and smallest (0.03e) for IV, resulting in ion pair I being the least polarized. A nucleus-independent chemical shift (NICS) study revealed that the aromaticity of the 1-butyl-2,4-dinitro-3-methyl imidazolium ion significantly increases in ion pair IV, indicating that this has the greatest charge delocalization among all of the four ion pairs considered. Studies of thermodynamic and detonation properties showed that ion pair II is the most energetic ion pair in terms of its detonation velocity (D = 7.5 km s(-1)) and detonation pressure (P = 23.1 GPa). It is also envisaged that ion pair IV would exist as an energetic azolium azolate type ionic liquid that could be conveniently used as a secondary explosive characterized by detonation parameters D and P of 6.9 km s(-1) and 19.3 GPa, respectively. These values are comparable to those of conventional explosives such as TNT. PMID:23392764

Singh, Hari Ji; Mukherjee, Uttama

2013-02-08

260

Photochromic imidazolium based ionic liquids based on spiropyran.  

PubMed

We investigate the physicochemical properties of a novel imidazolium benzospiropyran derivative, SP(Im), in imidazolium based ionic liquids (ILs). SP(Im) was prepared through alkylation of an imidazole to the photoswitchable compound and this derivative was characterised in imidazolium based ILs with increasing chain length to examine the stability of its merocyanine (MC) and spiropyran (SP) forms and compared to standard spiropyran, BSP. The rate of thermal relaxation of the new derivative is found to be about ten times faster than that of BSP as reflected in rates of 13.9 x 10(-3) s(-1) and 1.0 x 10(-3) s(-1) for SP(Im) and BSP, respectively, in [C(6)mIm][NTf(2)]. Since ILs are believed to form nano-structured domains it is proposed that the covalent attachment of the imidazolium side group of SP(Im) fully integrates the photoswitchable moiety into the non-polar region through side-chain association. In contrast, unbound BSP is relatively free to migrate between both polar and non-polar regions and the MC form is more readily stabilised by the IL charge via through space interactions and spontaneous movement to charged nano-domains leading to enhancement of the MC lifetime. At higher concentrations, rheological and transport properties were investigated to determine the impact of covalent attachment of the BSP fragment to an imidazolium cation on the ionic liquid structure. Ionic conductivity was found to decrease by up to 23% for SP(Im) with effects increasing with cation side-chain length. Unlike BSP, the photoswitching of the SP(Im) did not affect conductivity or viscosity values. This may indicate that the mobility of the photoswitchable compound and the resulting disruption of such movement may be critical to the control of this physical property. PMID:20467657

Coleman, Simon; Byrne, Robert; Alhashimy, Nameer; Fraser, Kevin J; Macfarlane, Douglas R; Diamond, Dermot

2010-05-13

261

Amphiphilic behavior of two phosphonium based ionic liquids.  

PubMed

Solution and surface chemical behavior of two phosphonium based ionic liquids triisobutyl (methyl) phosphonium tosylate (IL-1) and trihexyl (tetradecyl) phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (IL-2) have been studied. The polar IL-1 is surface active and water soluble, whereas the weakly polar IL-2 is more surface active with very low aqueous solubility. IL-1 does not form micelles but affects the micellization properties of ionic, nonionic, and zwitterionic surfactants more strongly than conventional electrolytes. IL-2 itself forms micelles and mixed micelles with Triton X-100 (TX-100) in aqueous solution. It also forms Langmuir monolayers of liquid expanded type, at the air/water interface. IL-1 can replace water in forming microemulsions with the oil isopropylmyristate (IPM), stabilized by IL-2 (surfactant)+isopropanol (IP as a co-surfactant) like the IL-1/IPM/(IL-2+IP) system. It produces a large monophasic zone in the pseudoternary phase diagram. The thermodynamics of formation of the microemulsions of IL-1 in oil (IPM) have been examined. The dimensions and the polydispersity of the dispersed nano-droplets in the microemulsions have been determined by DLS. The thermal stability of the microemulsion forming systems has also been studied. ILs studied against Sarcoma-180 cell lines have evidenced proficient anti-cancer activity of IL-1 and moderate activity of IL-2. PMID:23317771

Mukherjee, Indrajyoti; Mukherjee, Suvasree; Naskar, Bappaditya; Ghosh, Soumen; Moulik, Satya P

2012-12-19

262

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

263

Separation of Fission Products Based on Ionic Liquids: Anion Effect  

SciTech Connect

The applications of ionic liquids (ILs) as new separation media have been actively investigated recently. The most commonly studied class of ILs for such applications is based on dialkyl imidazolium cations. In comparison with conventional molecular solvents, ILs exhibit enhanced distribution coefficients for a number of complexing neutral ligands in extraction of metal ions from aqueous solutions. The effect of the alkyl chain length of imidazolium cations on the distribution coefficients of solvent extraction using crown ethers was the subject of a number of the previous investigations. The distribution coefficients have been found to decrease with the alkyl chain length of the IL cations. This observation implies that the extraction process also involves the exchange of the IL cations with metal ions. The longer the alkyl chain lengths of the IL cations are, the more hydrophobic the IL cations are and the more difficult to be transported into aqueous phases via ion exchange. Accordingly, the ion-exchange process is another unique property of IL-based extractions involving charged species. Here, we report the investigation about the effect of the variation of IL anions on the solvent extraction of metal ions using crown ethers as extractants. The elucidation of different solvation effects involved in ionic liquids could lead to optimized separation media for these novel solvents.

Luo, Huimin; Dai, Sheng; Bonnesen, Peter V.

2004-03-28

264

Carbon-centered strong bases in phosphonium ionic liquids.  

PubMed

Phosphonium ionic liquids (PhosILs), most notably tetradecyl(trihexyl)phosphonium decanoate (PhosIL-C(9)H(1)9COO), are solvents for bases such as Grignard reagents, isocyanides, Wittig reagents (phosphoranes), and N-heterocyclic carbenes (NHCs). The stability of the organometallic species in PhosIL solution is anion dependent. Small bases, such as hydroxide, react with the phosphonium ions and promote C-H exchange as suggested by deuterium-labeling studies. A method to dry and purify the ionic liquids is described and this step is important for the successful use of basic reagents in PhosIL. NHCs have been generated in PhosIL, and these persistent solutions catalyze organic transformations such as the benzoin condensation and the Kumada-Corriu cross-coupling reaction. Phosphoranes were generated in PhosIL, and their reactivity with various organic reagents was also tested. Inter-ion contacts involving tetraalkylphosphonium ions have been assessed, and the crystal structure of [(n-C(4)H(90)(4)P][CH(3)CO(2).CH(3)CO(2)H] has been determined to aid the discussion. Decomposition of organometallic compounds may also proceed through electron-transfer processes that, inter alia, may lead to decomposition of the IL, and hence the electrochemistry of some representative phosphonium and imidazolium ions has been studied. A radical derived from the electrochemical reduction of an imidazolium ion has been characterized by electron paramagnetic resonance spectroscopy. PMID:18173280

Ramnial, Taramatee; Taylor, Stephanie A; Bender, Marissa L; Gorodetsky, Brian; Lee, Peter T K; Dickie, Diane A; McCollum, Brett M; Pye, Cory C; Walsby, Charles J; Clyburne, Jason A C

2008-01-04

265

Using Ionic Liquids in Selective Hydrocarbon Conversion Processes  

SciTech Connect

This is the Final Report of the five-year project Using Ionic Liquids in Selective Hydrocarbon Conversion Processes (DE-FC36-04GO14276, July 1, 2004- June 30, 2009), in which we present our major accomplishments with detailed descriptions of our experimental and theoretical efforts. Upon the successful conduction of this project, we have followed our proposed breakdown work structure completing most of the technical tasks. Finally, we have developed and demonstrated several optimized homogenously catalytic methane conversion systems involving applications of novel ionic liquids, which present much more superior performance than the Catalytica system (the best-to-date system) in terms of three times higher reaction rates and longer catalysts lifetime and much stronger resistance to water deactivation. We have developed in-depth mechanistic understandings on the complicated chemistry involved in homogenously catalytic methane oxidation as well as developed the unique yet effective experimental protocols (reactors, analytical tools and screening methodologies) for achieving a highly efficient yet economically feasible and environmentally friendly catalytic methane conversion system. The most important findings have been published, patented as well as reported to DOE in this Final Report and our 20 Quarterly Reports.

Tang, Yongchun; Periana, Roy; Chen, Weiqun; van Duin, Adri; Nielsen, Robert; Shuler, Patrick; Ma, Qisheng; Blanco, Mario; Li, Zaiwei; Oxgaard, Jonas; Cheng, Jihong; Cheung, Sam; Pudar, Sanja

2009-09-28

266

Ionic liquids as solvents for in situ dispersive liquid-liquid microextraction of DNA.  

PubMed

Six ionic liquids (ILs) were applied for the first time as solvents in the extraction and preconcentration of deoxyribonucleic acid (DNA) using an in situ dispersive liquid-liquid microextraction (DLLME) approach. The effect of different IL substituents and functional group on the extraction efficiency of DNA was investigated. The highest extraction efficiencies of DNA were obtained using 1-(1,2-dihydroxypropyl)-3-hexadecylimidazolium bromide (C(16)POHIM-Br) and N,N-didecyl-N-methyl-d-glucaminium bromide [(C(10))(2)NMDG-Br]. Extraction efficiencies higher than 97% were obtained using small amounts of IL (0.50mg) for each extraction. The extraction of DNA from a sample matrix containing metal ions and protein revealed that the metal ions did not interfere with the extraction of DNA and that the co-extraction of protein can be mitigated by performing the extraction under moderately acidic conditions. Data from (31)P NMR spectroscopy suggest that a combination of electrostatic and ?-? interactions dominate IL-DNA complexation and that the extraction is concentration dependant. PMID:23261290

Li, Tianhao; Joshi, Manishkumar D; Ronning, Donald R; Anderson, Jared L

2012-11-28

267

Investigation of Carbon-2 Substituted Imidazoles and Their Corresponding Ionic Liquids  

SciTech Connect

The functionality at the C-2 position of the imidazole ring plays a key role in defining the chemical properties of the imidazoles and their corresponding ionic liquids. Imidazoles 1 6 with different C-2 functionality were synthesized and their corresponding ionic liquids were systematically investigated. Based on their physical properties the six imidazoles can be divided into three groups. 1) The imidazoles 2 and 3 are capable of self-polymerization to form poly(ionic liquid)s, and they are characterized with a strong leaving group at the C-2 position. 2) The imidazoles 4 and 5 can form ionic liquids, but they are very sensitive to moisture. 3) The imidazoles 1 and 6 can form stable ionic liquids, and their stabilities were influenced by the electronic effects of the substituents at the C-2 position.

Liao, Chen [ORNL; Xiang, Zhu [University of Tennessee, Knoxville (UTK); Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL

2011-01-01

268

Synthesis and mesomorphic properties of rigid-core ionic liquid crystals  

Microsoft Academic Search

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

Paul H. J. Kouwer; Timothy M. Swager

2007-01-01

269

A Diazonium Salt-Based Ionic Liquid for Solvent-FreeModification of Carbon  

Microsoft Academic Search

A novel ionic liquid that consists of p-butylbenzenediazonium ions and bis(trifluoromethanesulfonyl)amidates (TfN) has been synthesized as a task-specific ionic liquid for the solvent-free modification of carbon materials. The use of anions TfN{sup =} is the key to rendering the hydrophobicity, low liquidus temperature, and ionicity to this novel molten salt. This diazonium salt has a melting point of 7.2 C

Chengdu Liang; Jing-Fang Huang; Zuojiang Li; Huimin Luo; Sheng Dai

2006-01-01

270

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

271

Viscosity Measurements on Ionic Liquids: A Cautionary Tale  

NASA Astrophysics Data System (ADS)

The vibrating-wire viscometer has proven to be an exceedingly effective means of determining the viscosity of liquids over a wide range of temperature and pressure. The instrument has a long history but a variety of technological and theoretical developments over a number of years have improved its precision and most recently have enabled absolute measurements of high accuracy. However, the nature of the electrical measurements required for the technique has inhibited its widespread use for electrically conducting liquids so that there have been only a limited number of measurements. In the particular context of ionic liquids, which have themselves attracted considerable attention, this is unfortunate because it has meant that one primary measurement technique has seldom been employed for studies of their viscosity. In the last 2 years systematic efforts have been made to explore the applicability of the vibrating-wire technique by examining a number of liquids of increasing electrical conductivity. These extensions have been successful. However, in the process we have had cause to review previous studies of the viscosity and density of the same liquids at moderate temperatures and pressures and significant evidence has been accumulated to cause concern about the application of a range of viscometric techniques to these particular fluids. Because the situation is reminiscent of that encountered for a new set of environmentally friendly refrigerants at the end of the last decade, in this paper the experimental methods employed with these liquids have been reviewed which leads to recommendations for the handling of these materials that may have consequences beyond viscometric measurements. In the process new viscosity and density data for 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide [{C}6 mim][{NTf}2], 1-ethyl-3-methylimidazolium ethyl sulfate [{C}2 mim][{EtSO}4], and 1-ethyl-3-methylpyridinium ethyl sulfate [{C}2 mpy][{EtSO}4] have been obtained.

Diogo, João C. F.; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Wakeham, William A.

2013-07-01

272

Morphology, Modulus, and Ionic Conductivity of a Triblock Terpolymer/Ionic Liquid Electrolyte Membrane  

NASA Astrophysics Data System (ADS)

A key challenge in designing solid polymer electrolytes is increasing bulk mechanical properties such as stiffness, without sacrificing ionic conductivity. Previous work has focused on diblock copolymers, where one block is a stiff, glassy insulator and the other is a flexible ion conductor. Disadvantages of these systems include difficulty in achieving network morphologies, which minimize dead-ends for ion transport, and the necessity to operate below both the Tg of the glassy block and the order-disorder temperature. We have investigated the triblock terpolymer poly[isoprene-b-(styrene-co-norbornenylethyl styrene)-b-ethylene oxide] because it self-assembles into a triply-continuous network structure. SAXS and TEM revealed the bulk morphology of INSO to be disordered but strongly correlated after solvent casting from dichloromethane. This apparent disordered network structure was retained after chemical crosslinking and addition of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide. Impedance spectroscopy confirmed the expected conductivity for ions confined to continuous PEO channels. The mechanical response before and after crosslinking showed an increase in the material modulus.

McIntosh, Lucas D.; Lodge, Timothy P.

2013-03-01

273

Enhanced enantioselectivity of chiral hydrogenation catalysts after immobilisation in thin films of ionic liquid  

Microsoft Academic Search

Chiral organometallic complexes were immobilized in silica supported thin films of ionic liquid. The heterogenized catalysts were tested in the hydrogenation of acetophenone, which was chosen as test reaction for the enantioselective reduction of prochiral ketones. High enantioselectivities (up to 74% ee) were achieved in supported ionic liquids using a catalyst\\/substrate pair, which showed no enantioselectivity in methanol. This is

Kam Loon Fow; Stephan Jaenicke; Thomas E. Müller; Carsten Sievers

2008-01-01

274

Design and Evaluation of Ionic Liquids as Novel CO2 Absorbents  

Microsoft Academic Search

Progress from the fourth quarter 2005 activity on the project ''Design and Evaluation of Ionic Liquids as Novel COâ Absorbents'' is provided. Major activities in three areas are reported: compound synthesis, property measurement and molecular modeling. Last quarter we reported the first ever experimental measurement of SOâ solubility in an ionic liquid. We showed that SOâ was very soluble in

Edward J. Maginn

2006-01-01

275

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

276

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

277

Bis-sulfonic acid ionic liquids for the conversion of fructose to 5-hydroxymethyl-2-furfural.  

PubMed

Homogenous bis-sulfonic acid ionic liquids (1 mol equiv.) in DMSO (10 mol equiv.) at 100 °C efficiently mediated the conversion of D-fructose into 5-hydroxymethyl-2-furfural in 75% isolated yield, which was roughly a 10% increment compared to the case of the mono-sulfonic acid ionic liquids. PMID:23114616

Sim, Sang Eun; Kwon, Sunjeong; Koo, Sangho

2012-10-31

278

Visualization of Biomass Solubilization and Cellulose Regeneration during Ionic Liquid Pretreatment of Switchgrass  

Technology Transfer Automated Retrieval System (TEKTRAN)

Auto-fluorescent mapping of plant cell walls was used to visualize cellulose and lignin in pristine switchgrass (Panicum virgatum) stems to determine the mechanisms of biomass dissolution during ionic liquid pretreatment. The addition of ground switchgrass to the ionic liquid 1-n-ethyl-3-methylimid...

279

Methods of using ionic liquids having a fluoride anion as solvents  

Microsoft Academic Search

A method in one embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having a fluoride anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of about 90.degree. C. or less during the contacting. A method in another embodiment includes contacting a strongly hydrogen bonded organic material with

Philip Pagoria; Amitesh Maiti; Alexander Gash; Thomas Yong Han; Christine Orme; Laurence Fried

2011-01-01

280

Direct UV-spectroscopic measurement of selected ionic-liquid vapors  

SciTech Connect

The hallmark of ionic liquids lies in their negligible vapor pressure. This ultralow vapor pressure makes it difficult to conduct the direct spectroscopic measurement of ionic-liquid vapors. In fact, there have been no electronic spectroscopic data currently available for ionic-liquid vapors. This deficiency significantly hampers the fundamental understanding of the unique molecular structures of ionic liquids. Herein, the UV absorption spectra of eight ionic liquids, such as 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim{sup +}] [Tf{sub 2}N{sup -}]) and 1-ethyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide ([Emim{sup +}][beti{sup -}]) in the vapor phase in a distillation-like environment, were measured through a high-temperature spectroscopic technique to fill this knowledge gap. Two strong absorption peaks of the [Bmim{sup +}][Tf{sub 2}N{sup -}] vapor lie at 202 and 211 nm, slightly different from those of the neat [Bmim{sup +}][Tf{sub 2}N{sup -}] thin film and its solution in water. Based on the quantitative determination of the vapor absorption spectra as a function of temperature, the vaporization enthalpies of these ionic liquids vapors were measured and found to be in good agreement with the corresponding literature values. This in situ method opens up a new avenue to study the nature of ionic-liquid vapors and to determine the vaporization enthalpies of ionic liquids.

Dai, Sheng [ORNL; Luo, Huimin [ORNL; Wang, Congmin [ORNL; Li, Haoran [Zhejiang University

2010-01-01

281

Coupled Ion Complexation and Exchange between Aqueous and Ionic Liquid Phases: A Thermodynamic Interpretation  

Microsoft Academic Search

Experimental studies of ion extraction from aqueous to ionic liquid phases have demonstrated that, in many cases, extraction of an ion from the aqueous phase is coupled to counterextraction of similarly charged ions from the ionic phase. These exchanges often involve coordination complexes that are not observed in extractions from aqueous phases to molecular organic liquids. We make a thermodynamic

Mark N. Kobrak

2008-01-01

282

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns  

SciTech Connect

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs generally have low volatilities and are combustion-resistant, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of primary radiation chemistry, charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of reactions and product distributions. We study these issues by characterization of primary radiolysis products and measurements of their yields and reactivity, quantification of electron solvation dynamics and scavenging of electrons in different states of solvation. From this knowledge we wish to learn how to predict radiolytic mechanisms and control them or mitigate their effects on the properties of materials used in nuclear fuel processing, for example, and to apply IL radiation chemistry to answer questions about general chemical reactivity in ionic liquids that will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that the slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increase the importance of pre-solvated electron reactivity and consequently alter product distributions and subsequent chemistry. This difference from conventional solvents has profound effects on predicting and controlling radiolytic yields, which need to be quantified for the successful use under radiolytic conditions. Electron solvation dynamics in ILs are measured directly when possible and estimated using proxies (e.g. coumarin-153 dynamic emission Stokes shifts or benzophenone anion solvation) in other cases. Electron reactivity is measured using ultrafast kinetics techniques for comparison with the solvation process.

Wishart, J.F.

2011-06-12

283

Mutual Lewis Acid-Base Interactions of Cations and Anions in Ionic Liquids  

PubMed Central

Solute properties are known to be strongly influenced by solvent molecules due to solvation. This is due to mutual interaction as both the properties of the solute and of the solvent strongly depend on each other. The present paper is based on the idea that ionic liquids are cations solvated by anions and anions solvated by cations. To show this (in this system strongly pronounced) interaction the long time established donor–acceptor concept for solvents and ions in solution by Viktor Gutmann is extended to ionic liquids. A number of solvent parameters, such as the Kamlet–Abboud–Taft and the Dimroth–Reichardt ET scale for ionic liquids neglect this mutual influence, which, however, seems to be in fact necessary to get a proper description of ionic liquid properties. It is shown how strong such parameters vary when the influence of the counter ion is taken into account. Furthermore, acceptor and donor numbers for ionic liquids are presented.

Holzweber, Markus; Lungwitz, Ralf; Doerfler, Denise; Spange, Stefan; Koel, Mihkel; Hutter, Herbert; Linert, Wolfgang

2013-01-01

284

Mesoporous and biocompatible surface active silica aerogel synthesis using choline formate ionic liquid.  

PubMed

In this paper, we report the preparation and characterization of mesoporous and biocompatible transparent silica aerogel by the sol-gel polymerization of tetraethyl orthosilicate using ionic liquid. Choline cation based ionic liquid allows the silica framework to form in a non collapsing environment and controls the pore size of the gel. FT-IR spectra reveal the interaction of ionic liquid with surface -OH of the gel. DSC thermogram giving the evidence of confinement of ionic liquid within the silica matrix, which helps to avoid the shrinkage of the gel during the aging process. Nitrogen sorption measurements of gel prepared with ionic liquid exhibit a low surface area of 100.53 m2/g and high average pore size of 3.74 nm. MTT assay proves the biocompatibility and cell viability of the prepared gels. This new nanoporous silica material can be applied to immobilize biological molecules, which may retain their stability over a longer period. PMID:21565470

Meera, Kamal Mohamed Seeni; Sankar, Rajavelu Murali; Jaisankar, Sellamuthu N; Mandal, Asit Baran

2011-04-15

285

A classical density functional theory for interfacial layering of ionic liquids  

SciTech Connect

Ionic liquids have attracted much recent theoretical interest for broad applications as environmentally-friendly solvents in separation and electrochemical processes. Because of the intrinsic complexity of organic ions and strong electrostatic correlations, the electrochemical properties of ionic liquids often defy the descriptions of conventional mean-field methods including the venerable, and over-used, Gouy-Chapman-Stern (GCS) theory. Classical density functional theory (DFT) has proven to be useful in previous studies of the electrostatic properties of aqueous electrolytes but until recently it has not been applied to ionic liquids. Here we report predictions from the DFT on the interfacial properties of ionic liquids near neutral or charged surfaces. By considering the molecular size, topology, and electrostatic correlations, we have examined major factors responsible for the unique features of electric-double layers of ionic-liquid including formation of long-range and alternating structures of cations and anions at charged surfaces.

Wu, Jianzhong [University of California, Riverside; Jiang, Tao [California Energy Commission; Jiang, Deen [ORNL; Jin, Zhehui [University of California, Riverside; Henderson, Douglous [Brigham Young University

2011-01-01

286

Ionic liquid-solid-polymer mixed matrix membranes for gas separations  

US Patent & Trademark Office Database

New ionic liquid-solid-polymer mixed matrix membranes were proposed for gas separations such as CO.sub.2 removal from natural gas or N.sub.2. For the new mixed matrix membranes, the solids such as carbon molecular sieves, microporous molecular sieves, MCM-41 type of mesoporous molecular sieves, or polymer of intrinsic microporosity (PIM) are coated (or impregnated) with ionic liquids such as 1-butyl-3-methyl imidazolium bis[trifluoromethylsulfonyl]amide. The ionic liquids coated or impregnated solids are then dispersed in the continuous polymer matrix to form mixed matrix membranes. These hybrid mixed matrix membranes will combine the properties of the continuous polymer phase, the ionic liquids, and the dispersed ionic liquids coated or impregnated solids phase, which will possibly open up new opportunities for gas separation processes such as CO.sub.2 separation from natural gas or flue gas.

Liu; Chunqing (Schaumburg, IL); Kulprathipanja; Santi (Inverness, IL); Schott; Mark E. (Palatine, IL); Wilson; Stephen T. (Libertyville, IL)

2011-05-17

287

Raman spectra of ionic liquids: Interpretation via computer simulation  

NASA Astrophysics Data System (ADS)

Theoretical Raman spectra of the complex-forming ionic liquids LaCl3 and ScCl3, derived from molecular dynamics computer simulations, are presented. These simulations, which use polarizable ion interaction models, have previously been shown to predict structural properties in excellent agreement with diffraction experiments. The dependence of the polarizability of the melt on the ionic positions, which determines the Raman spectrum through the time dependence of the polarizability correlation function, is modeled on the basis of ab initio electronic structure calculations carried out on alkali chlorides. New simulation techniques are introduced in order to allow the spectrum to be calculated with acceptable statistics. The calculated spectra are in semiquantitative agreement with experimental data. The distinctive bands which appear in the spectra of such complex melts are linked to the vibrations of the transient coordination complexes which form in these melts and new interpretations for the origin of several well-known features are proposed. The simulations thus enable a link between the structure of a melt as perceived through Raman spectroscopy and through diffraction experiments to be made.

Madden, Paul A.; Wilson, Mark; Hutchinson, Francis

2004-04-01

288

Raman spectra of ionic liquids: interpretation via computer simulation.  

PubMed

Theoretical Raman spectra of the complex-forming ionic liquids LaCl3 and ScCl3, derived from molecular dynamics computer simulations, are presented. These simulations, which use polarizable ion interaction models, have previously been shown to predict structural properties in excellent agreement with diffraction experiments. The dependence of the polarizability of the melt on the ionic positions, which determines the Raman spectrum through the time dependence of the polarizability correlation function, is modeled on the basis of ab initio electronic structure calculations carried out on alkali chlorides. New simulation techniques are introduced in order to allow the spectrum to be calculated with acceptable statistics. The calculated spectra are in semiquantitative agreement with experimental data. The distinctive bands which appear in the spectra of such complex melts are linked to the vibrations of the transient coordination complexes which form in these melts and new interpretations for the origin of several well-known features are proposed. The simulations thus enable a link between the structure of a melt as perceived through Raman spectroscopy and through diffraction experiments to be made. PMID:15267553

Madden, Paul A; Wilson, Mark; Hutchinson, Francis

2004-04-01

289

Stable prenucleation mineral clusters are liquid-like ionic polymers.  

PubMed

Calcium carbonate is an abundant substance that can be created in several mineral forms by the reaction of dissolved carbon dioxide in water with calcium ions. Through biomineralization, organisms can harness and control this process to form various functional materials that can act as anything from shells through to lenses. The early stages of calcium carbonate formation have recently attracted attention as stable prenucleation clusters have been observed, contrary to classical models. Here we show, using computer simulations combined with the analysis of experimental data, that these mineral clusters are made of an ionic polymer, composed of alternating calcium and carbonate ions, with a dynamic topology consisting of chains, branches and rings. The existence of a disordered, flexible and strongly hydrated precursor provides a basis for explaining the formation of other liquid-like amorphous states of calcium carbonate, in addition to the non-classical behaviour during growth of amorphous calcium carbonate. PMID:22186886

Demichelis, Raffaella; Raiteri, Paolo; Gale, Julian D; Quigley, David; Gebauer, Denis

2011-12-20

290

Mechanisms of degradation of paraoxon in different ionic liquids.  

PubMed

Herein, the reactivity and selectivity of the reaction of O,O-diethyl 4-nitrophenyl phosphate triester (Paraxon, 1) with piperidine in ionic liquids (ILs), three conventional organic solvents (COS), and water is studied by (31)P NMR, UV-vis, and GC/MS. Three phosphorylated products are identified as follows: O,O-diethyl piperidinophosphate diester (2), O,O-diethyl phosphate (3), and O-ethyl 4-nitrophenyl phosphate diester (4). Compound 4 also reacts with piperidine to yield O-ethyl piperidinophosphate monoester (5). The results show that both the rate and products distribution of this reaction depend on peculiar features of ILs as reaction media and the polarity of COS. PMID:24001321

Pavez, Paulina; Millán, Daniela; Morales, Javiera I; Castro, Enrique A; López A, Claudio; Santos, José G

2013-09-17

291

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

292

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

293

Molecular simulation of guanidinium-based ionic liquids.  

PubMed

A new systematic all-atom force field was developed for cyclic guanidinium-based ionic liquids (ILs) based on the AMBER force field. Optimized molecular geometries and equilibrium bond lengths and angles were obtained by ab initio calculations, and charges were allocated to each atom center by fitting the ab initio electrostatic potential. Molecular dynamics simulations were performed for eleven kinds of ILs that are comprised of NO3(-) anions and cyclic guanidinium-based cations. Validation was carried out by comparing our simulated densities with experimental and calculated data from the literature. Transport properties such as self-diffusion coefficients, viscosities, and conductivities were calculated by molecular dynamic simulation, and their dependence on the length of the alkyl chains of cyclic guanidinium-based cations are discussed. Radial distribution functions and spatial distribution functions were investigated to depict the microscopic structures of the ILs, and the relationship between their properties and microstructures is also discussed. PMID:17469867

Liu, Xiaomin; Zhou, Guohui; Zhang, Suojiang; Wu, Guangwen; Yu, Guangren

2007-05-01

294

Task Specific Ionic Liquids and Task Specific Onium Salts  

NASA Astrophysics Data System (ADS)

Task specific ionic liquids (TSILs), or more generally task specific onium salts (TSOSs), can be defined as an association of a cation and anion, one at least being organic, to which has covalently been attached through a linker a function that confers the assembly a specific task. After presentation of the general concept of TSILs and TSOSs, the different methods of preparation of these compounds are developed. Regarding their applications in chemistry, TSILs and TSOSs can be used as soluble supports for reagents and catalysts in multiphasic reactions, enabling high activity and easy recovery of the supported agent. However, additionally, they can be used as soluble supports for organic synthesis in a similar manner to resins and offer several advantages over traditional methods.

Pucheault, Mathieu; Vaultier, Michel

295

Correlation between thermostability and stability of glycosidases in ionic liquid.  

PubMed

The activity and stability of a ?-glycosidase (Thermus thermophilus) and two ?-galactosidases (Thermotoga maritima and Bacillus stearothermophilus) were studied in different hydrophilic ionic liquid (IL)/water ratios. For the ILs used, the glycosidases showed the best stability and activity in 1,3-dimethylimidazolium methyl sulfate [MMIM][MeSO(4)] and 1,2,3-trimethylimidazolium methyl sulfate [TMIM][MeSO(4)]. A close correlation was observed between the thermostability of the enzymes and their stability in IL media. At high IL concentration (80%), a time-dependent irreversible denaturing effect was observed on glycosidases while, at lower concentration (<30%), a reversible inactivation affecting mainly the k (cat) was obtained. The results demonstrate that highly thermostable glycosidases are more suitable for biocatalytic reactions in water-miscible ILs. PMID:21331585

Ferdjani, Salim; Ionita, Marina; Roy, Bimalendu; Dion, Michel; Djeghaba, Zeineddine; Rabiller, Claude; Tellier, Charles

2011-02-18

296

Surface Studies on the Ionic Liquid 1Ethyl3-Methylimidazolium Ethylsulfate Using X-Ray Photoelectron Spectroscopy (XPS)  

Microsoft Academic Search

Surface studies of ionic liquids are particularly important for all kinds of multiphasic operations employing ionic liquids, e.g. biphasic homogeneous catalysis or supported ionic liquid phase catalysis. Using X-ray photoelectron spectroscopy (XPS), the surface com- position of the model system 1-ethyl-3-methylimidazolium ethylsulfate (EMIM)(EtOSO3) was investigated. By comparing two different samples of this ionic liquid from two different origins, we observed

J. M. Gottfried; D. Gerhard; P. S. Schulz; P. Wasserscheid; H.-P. Steinrück

2006-01-01

297

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

298

An MD study of the applicability of the Walden rule and the Nernst-Einstein model for ionic liquids.  

PubMed

Six different ionic liquids containing imidazolium, pyrrolidinium and ammonium cations paired with bis[(trifluoromethyl)sulfonyl]imide and bis[(perfluoroethyl)sulfonyl]imide anions were studied using molecular dynamics simulations. Ionic conductivities, shear viscosities and self-diffusivities were computed and compared to see what relationships exist between these three transport properties. The simulations suggest that these ionic liquids follow closely the Walden rule, which relates ionic conductivity to fluidity. The computed ionic conductivities agree well with those predicted from the Nernst-Einstein model, suggesting that long-time correlation among ion velocities is small, or that the "ionicity" of these ionic liquids is high. PMID:22378767

Liu, Hongjun; Maginn, Edward

2012-02-29

299

Studies on the dissolution of glucose in ionic liquids and extraction using the antisolvent method.  

PubMed

Biomass, the fibrous material derived from plant cell walls, is a potentially clean and renewable nonfood feedstock for liquid fuel and chemical production in future biorefineries. The capability of ionic liquids to act as selective solvents and catalysts for biomass processing has already been proven. Thus, they are considered as an alternative to conventional solvents. Nevertheless, phase equilibria with biomass derived compounds is still lacking in the literature. To overcome the lack of experimental data on phase equilibria of biomass carbohydrates in ionic liquids, the solubility of d-glucose in four ionic liquids was measured within a temperature range from 283 to 373 K. Solubility data were successfully correlated with local composition thermodynamic models such as NRTL and UNIQUAC. In this work, the possibility of extracting glucose from these ionic liquids using the antisolvent method has been also evaluated. The parameters affecting the extraction process are the ionic liquid type, ethanol/ionic liquid ratio, temperature, water content, and time. Results indicate that ethanol can be successfully used as an antisolvent to separate glucose from ionic liquids. PMID:23398175

Hassan, El-Sayed R E; Mutelet, Fabrice; Pontvianne, Steve; Moïse, Jean-Charles

2013-02-22

300

STRUCTURE AND PROPERTIES OF CORN, RICE, WHEAT AND POTATO STARCH DISPERSED IN THE IONIC LIQUID, 1-BUTYL-3-METHYLIMIDAZOLIUM CHLORIDE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ionic liquid has gained industry attention, especially in environmentally friendly green chemistry. Researchers have utilized ionic liquid for dispersing cellulose, but no report using ionic liquid for other polysaccharides. In this study, corn, rice, wheat and potato starches were dispersed in ho...

301

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

302

Prominent roles of impurities in ionic liquid for catalytic conversion of carbohydrates  

SciTech Connect

In the last two decades, ionic liquids have emerged as new and versatile solvents, and many of them are also catalysts for a broad range of catalytic reactions. Certain ionic liquids have been found to possess the unique capability of dissolving cellulosic biomass. The potential of such ionic liquids as solvent to enable catalytic conversion of cellulosic polymers was first explored and demonstrated by Zhao et al. This field of research has since experienced a rapid growth. Most ionic liquids have negligible vapor pressure and excellent thermal stability over a wide temperature range. For example, ionic liquids composed of 1-ethyl-3-methylimidazolium (EMIM+) cation and Cl- anion was reported to be stable up to 285 C, while salts of the same cation with other anions such as BF4- and PF6- are thermally stable above 380 C under inert atmosphere. It is well known that presence of impurities in ionic liquids typically causes changes in physical properties, e.g. decreasing in melting point and viscosity. Addition of Lewis acidic metal chlorides, e.g. AlCl3 to 1-alkyl-3-methylimidazolium chloride, [AMIM]Cl, is an exothermic reaction and considerably reduces the melting point by forming [AMIM]AlCl4 or [AMIM]Al2Cl7 that are also ionic liquids but have much lower melting point than the parent [AMIM]Cl. While most early research on catalysis of ionic liquids involving metallohalide anions were typically conducted from stoichiometric ratio of such anions to organic cations, e.g. [AMIM]+, the use of pure ionic liquids only as a solvent to carry out catalysis by a catalytic amount of a metal halide as catalyst truly displayed the solvent property of such ionic liquids.4 In such reaction systems, catalytic amounts of metal halides were used to catalyze the conversion of glucose and cellulose.4,11,12 The metal chloride catalyst concentration was in the order of 10-3 M. The presence of another metal chloride in the ionic liquids, even in the order of 10-5 M concentration was found to bring a dramatic synergistic effect. Therefore, the catalytic performance of the metal halide catalyst for the conversion of carbohydrates in the ionic liquid systems is highly sensitive to the presence of impurities. This work presents findings on the role of impurities that were present in some commercially available ionic liquids used for the conversion of the cellulose.

Zhao, Haibo; Brown, Heather M.; Holladay, Johnathan E.; Zhang, Z. Conrad

2012-02-07

303

Liquid-phase synthesis of polyhydroquinoline using task-specific ionic liquid technology.  

PubMed

A new strategy for the synthesis of polyhydroquinolines from task-specific ionic liquids (TSIL) as a soluble support was developed. The preparation of the polyhydroquinolines by a three-component reaction was achieved by using ionic liquid-phase bound beta-oxo esters. These starting functionalized esters were synthesized by a solventless transesterification without catalyst under microwave irradiation. The structure of the intermediates in each step was verified routinely by spectroscopic analysis, and after oxidation of the polyhydroquinolines grafted on the TSIL with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or after cleavage (transesterification, saponification-acidification), the target compounds were obtained in good yields and high purities. PMID:17096571

Legeay, Jean Christophe; Goujon, Jean Yves; Vanden Eynde, Jean Jacques; Toupet, Loic; Bazureau, Jean Pierre

304

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

305

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

306

Alkylammonium Formate Ionic Liquids as Organic Mobile Phase Replacements for Reversed?Phase Liquid Chromatography  

Microsoft Academic Search

Alkylammonium formate (AAF) ionic liquids, RNH3 [HCO2 ], R=C2H5, C3H7, or C4H9, are prepared in high yield and purity by slowly reacting an alkylamine and formic acid in an ice bath under N2. UV spectra of undiluted ethylammonium formate (EAF), n?propylammonium formate (PAF), n?butylammonium formate (BAF) show no appreciable background absorbance down to about 250 nm, 270 nm, and 295 nm, respectively. Physical

Martin M. Waichigo; Brian M. Hunter; Thomas L. Riechel; Neil D. Danielson

2007-01-01

307

Effect of ionic liquids on (vapor + liquid) equilibrium behavior of (water + 2-methyl-2-propanol)  

Microsoft Academic Search

Isobaric T, x, y data were reported for ternary systems of {water+2-methyl-2-propanol (tert-butyl alcohol, TBA)+ionic liquid (IL)} at p=100kPa. When the mole fraction of TBA on IL-free basis was fixed at 0.95, measurements were performed at IL mass fractions from 0.6 down to 0.05, in a way of repeated synthesis. The vapor-phase compositions were obtained by analytical methods and the

Lianzhong Zhang; Bingbang Qiao; Yun Ge; Dongshun Deng; Jianbing Ji

2009-01-01

308

Why Are Ionic Liquids Liquid? A Simple Explanation Based on Lattice and Solvation Energies  

Microsoft Academic Search

We have developed a simple and quantitative explanation for the relatively low melting temperatures of ionic liquids (ILs). The basic concept was to assess the Gibbs free energy of fusion (¢fusG) for the process IL(s) f IL(l), which relates to the melting point of the IL. This was done using a suitable Born-Fajans-Haber cycle that was closed by the lattice

Ingo Krossing; John M. Slattery; Corinne Daguenet; Paul J. Dyson; Alla Oleinikova; Hermann Weingartner

2006-01-01

309

Purification of ionic liquids by supercritical CO 2 monitored by infrared spectroscopy  

Microsoft Academic Search

Transmission infrared and Attenuated Total Reflection (ATR) in situ infrared spectroscopies were combined for the time-resolved monitoring of both liquid and supercritical phases during extraction of water and other impurities from ionic liquids with supercritical carbon dioxide (scCO2). Cleaning and drying by scCO2 at 100bar and 40°C proved to be efficient for all ionic liquids tested, including 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]),

Jean-Michel Andanson; Fabian Jutz; Alfons Baiker

2010-01-01

310

Electrowetting of Ionic Liquids on Teflon AF1600 in Ambient Hexadecane  

Microsoft Academic Search

A droplet of ionic liquid is immersed in an immiscible liquid (n-hexadecane) and electrowetted on a flat electrode insulated with Teflon AF1600. Two series of ionic liquids were studied: 1-alkyl-3-methylimidazolium tetrafluoroborates (Rmim.BF4) and 1-butyl-3-methylimidazolium with various anions (bmim.X). When voltage is applied between the droplet and the electrode, the static contact angle decreases from about 150° down to 50° (with

Mani Paneru; Craig Priest; John Ralston; Rossen Sedev

2012-01-01

311

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

312

Direct Capture of Organic Acids From Fermentation Media Using Ionic Liquids  

SciTech Connect

Several ionic liquids have been investigated for the extraction of organic acids from fermentation broth. Partitioning of representative organic acids (lactic, acetic, and succinic) between aqueous solution and nine hydrophobic ionic liquids was measured. The extraction efficiencies were strongly dependent on pH of the aqueous phase. Distribution coefficient was very good (approximately 60) at low succinic acid concentrations for one of the ionic liquids (trihexyltetradecylphosphonium methanesulfonate) at neutral pH. However, this ionic liquid had to be diluted with nonanol due to its high viscosity in order to be useful. A diluent (trioctylamine) was also added to this mixture. The results suggest that an extraction system based on ionic liquids may be feasible for succinic acid recovery from fermentation broth and that two ideal extraction stages are needed to reduce the concentration from 33 g/L to 1 g/L of succinic acid. Further studies are needed to evaluate other issues related to practical applications, including ionic liquid loss in the process, toxicity effects of ionic liquids during simultaneous fermentation and extractions.

Klasson, K.T.

2004-11-03

313

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

314

In-situ ionic liquid-dispersive liquid-liquid microextraction method to determine endocrine disrupting phenols in seawaters and industrial effluents  

Microsoft Academic Search

We have evaluated an in-situ ionic liquid-dispersive liquid-liquid microextraction procedure for the determination of six\\u000a endocrine disrupting phenols in seawaters and industrial effluents using HPLC. The optimized method requires 38 ?L of the\\u000a water-soluble ionic liquid 1-butyl-3-methylimidazolium chloride, and 5 mL of seawater or industrial effluent. After appropriate\\u000a work-up, a drop (~10 ?L) of an ionic liquid is formed that contains the analytes

Jessica López-Darias; Verónica Pino; Juan H. Ayala; Ana M. Afonso

315

Synthesis, characterization and the antimicrobial activity of new eco-friendly ionic liquids.  

PubMed

A green microwave-assisted procedure for the preparation of a series of 24 new 1-alkyl-3-ethylimidazolium ionic liquids with different functional groups in the alkyl chain is described. Moreover, the synthesis of a variety of ten new geminal dicationic ionic liquids is reported. Their structures were characterized by FT-IR, (1)H NMR, (13)C NMR, (11)B, (19)F, (31)P, and mass spectrometry. Several ionic liquids were selected for antimicrobial activity studies, yielding very interesting and promising results. PMID:23357867

Messali, Mouslim; Moussa, Ziad; Alzahrani, Abdullah Y; El-Naggar, Moustafa Y; ElDouhaibi, Ahmad S; Judeh, Zaher M A; Hammouti, Belkheir

2013-01-26

316

Nicotine: on the potential role of ionic liquids for its processing and purification.  

PubMed

Marked solubility differences of nicotine in the ionic liquids [C(2)mim][NTf(2)], [C(2)mim][EtOSO(3)], and [C(n)mim]Cl, 6 ionic liquids to extract and purify this important compound. From a fundamental standpoint, the generally enhanced solubility of nicotine in these ionic liquids as compared to that of aromatic and aliphatic hydrocarbons can be assigned to the presence of the aromatic pyridine ring and the large aliphatic N-methyl-pyrrolidine residue. PMID:17595131

Visak, Zoran P; Yague, Susana Lucas; Lopes, José N Canongia; Rebelo, Luis Paulo N

2007-06-27

317

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

318

Comparison of physicochemical properties of new ionic liquids based on imidazolium, quaternary ammonium, and guanidinium cations.  

PubMed

More than 50 ionic liquids were prepared by using imidazolium, quaternary ammonium, and guanidinium cations and various anions. In these series, different cationic structures such as 1-benzyl-3-methylimidazolium [Bzmim]+, 1,3-dibenzylimidazolium [BzmiBz]+, 1-octyl-3-methylimidazolium [C8mim]+, 1-decyl-3-methylimidazolium [C10mim]+, tricapryl-methylammonium [Aliquat]+, benzyltriethylammonium [BzTEA]+, phenyltrimethylammonium [PhTMA]+, and dimethyldihexylguanidinium [DMG]+ were combined with anions, p-toluenesulfonate [TSA](-), dicyanoamide [DCA]-, saccharine (2-sulfobenzoic acid imide sodium salt) [SAC]-, trifluoroacetate [TFA]-, bis(trifluoromethanesulfonyl)imide [Tf2N]-, trifluoromethanesulfonate [TfO]-, and thiocyanate [SCN]-. Important physical data for these ionic liquids are collated, namely solubility in common solvents, viscosity, density, melting point and water content. Apart from the viscosity, the Newtonian and non-Newtonian behavior of these ionic liquids is also disclosed. Stability of these ionic liquids under thermal, basic, acidic, nucleophilic, and oxidative conditions was also studied. The features of the solid-liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. A degradation temperature of each ionic liquid was also determined. Comparisons of the properties of various ionic liquids were made. PMID:17665379

Kulkarni, Prashant S; Branco, Luís C; Crespo, João G; Nunes, M Cristiana; Raymundo, Anabela; Afonso, Carlos A M

2007-01-01

319

Protic ionic liquids based on phosphonium cations: comparison with ammonium analogues.  

PubMed

Novel protic ionic liquids (PILs) based on a tributyl phosphonium cation have been synthesised and characterised, revealing that the phosphonium based ILs show high thermal stability, high ionic conductivity and facile proton reduction compared to the corresponding ammonium based ILs. PMID:21963830

Rana, Usman Ali; Vijayaraghavan, R; Walther, Mareike; Sun, Jiazeng; Torriero, Angel A J; Forsyth, Maria; MacFarlane, Douglas R

2011-09-30

320

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

321

Density scaling of the transport properties of molecular and ionic liquids  

NASA Astrophysics Data System (ADS)

Casalini and Roland [Phys. Rev. E 69, 062501 (2004); J. Non-Cryst. Solids 353, 3936 (2007)] and other authors have found that both the dielectric relaxation times and the viscosity, ?, of liquids can be expressed solely as functions of the group (TV ?), where T is the temperature, V is the molar volume, and ? a state-independent scaling exponent. Here we report scaling exponents ?, for the viscosities of 46 compounds, including 11 ionic liquids. A generalization of this thermodynamic scaling to other transport properties, namely, the self-diffusion coefficients for ionic and molecular liquids and the electrical conductivity for ionic liquids is examined. Scaling exponents, ?, for the electrical conductivities of six ionic liquids for which viscosity data are available, are found to be quite close to those obtained from viscosities. Using the scaling exponents obtained from viscosities it was possible to correlate molar conductivity over broad ranges of temperature and pressure. However, application of the same procedures to the self-diffusion coefficients, D, of six ionic and 13 molecular liquids leads to superpositioning of poorer quality, as the scaling yields different exponents from those obtained with viscosities and, in the case of the ionic liquids, slightly different values for the anion and the cation. This situation can be improved by using the ratio (D/T), consistent with the Stokes-Einstein relation, yielding ? values closer to those of viscosity.

López, Enriqueta R.; Pensado, Alfonso S.; Comuñas, María J. P.; Pádua, Agílio A. H.; Fernández, Josefa; Harris, Kenneth R.

2011-04-01

322

Alkylpyridinium Alkylsulfate Ionic Liquids as Solvents for the Deterpenation of Citrus Essential Oil  

Microsoft Academic Search

The ionic liquids 1-methylpyridinium methylsulfate and 1-ethylpyridinium ethylsulfate were tested as solvents for the deterpenation by liquid-liquid extraction of citrus essential oil, simulated as a mixture of limonene and linalool. Liquid-liquid equilibrium data for the ternary systems limonene + linalool + 1-alkylpyridinium alkylsulfate (with the alkyl chain being methyl or ethyl) were determined at 298.15 K and atmospheric pressure, and suitably correlated with the UNIQUAC

Sara Lago; Héctor Rodríguez; Ana Soto; Alberto Arce

2012-01-01

323

Alkylpyridinium Alkylsulfate Ionic Liquids as Solvents for the Deterpenation of Citrus Essential Oil  

Microsoft Academic Search

The ionic liquids 1-methylpyridinium methylsulfate and 1-ethylpyridinium ethylsulfate were tested as solvents for the deterpenation by liquid-liquid extraction of citrus essential oil, simulated as a mixture of limonene and linalool. Liquid-liquid equilibrium data for the ternary systems limonene + linalool + 1-alkylpyridinium alkylsulfate (with the alkyl chain being methyl or ethyl) were determined at 298.15 K and atmospheric pressure, and suitably correlated with the UNIQUAC

Sara Lago; Héctor Rodríguez; Ana Soto; Alberto Arce

2011-01-01

324

Properties of chitosan-immobilized cellulase in ionic liquid.  

PubMed

The properties of cellulase that was attached to the surface of the chitosan carrier in aqueous-ionic liquid (IL; 1,3-dimeth-ylimidazolium dimethylphosphate) mixture were studied. The optimal temperature for immobilized cellulase in aqueous-IL mixed solutions was 60 °C. The immobilized cellulase acquired the highest relative activity at a ratio of 1:4 (IL to water, v/v), compared to activity levels of 79% and 7%, when the ratio of IL to water (v/v) was 0:1 and 1:0, respectively. At 80 °C, the immobilized cellulase in the aqueous-IL mixture conserved 46.3% activity after 120 Min. The immobilized cellulase can be effectively reused three times. After 4 weeks, the activity of immobilized cellulase maintained 83.5%. The Michaelis constant (Km ) and maximum reaction velocity (Vm ) values for the immobilized cellulase were 4.8 mg/L and 0.156 mg/(mL Min), respectively. To the best of our knowledge, this is the first report on the properties of chitosan-immobilized cellulase in aqueous-IL. PMID:23586334

Su, Zhongliang; Yu, Yang; Liang, Chengwei; Li, Lu; Yu, Shitao

2013-01-11

325

Paramagnetic ionic liquids for measurements of density using magnetic levitation.  

PubMed

Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic object can be determined by measuring its position in the magnetic field along the vertical axis (levitation height, h), either as an absolute value or relative to internal standards of known density. For density measurements by MagLev, PILs have three advantages over solutions of paramagnetic salts in aqueous or organic solutions: (i) negligible vapor pressures; (ii) low melting points; (iii) high thermal stabilities. In addition, the densities, magnetic susceptibilities, glass transition temperatures, thermal decomposition temperatures, viscosities, and hydrophobicities of PILs can be tuned over broad ranges by choosing the cation-anion pair. The low melting points and high thermal stabilities of PILs provide large liquidus windows for density measurements. This paper demonstrates applications and advantages of PILs in density-based analyses using MagLev. PMID:23972068

Bwambok, David K; Thuo, Martin M; Atkinson, Manza B J; Mirica, Katherine A; Shapiro, Nathan D; Whitesides, George M

2013-08-23

326

Antimicrobial membrane cellulose acetate containing ionic liquid and metal nanoparticles.  

PubMed

Stable metallic Au(0), Ag(0) and Pt(0) nanoparticle-containing membrane films (20 microm thickness) were obtained by combining irregularly shaped nanoparticles of monomodal size distributions (11 +/- 1.5 nm Au(0), 8.9 +/- 2.1 nm Ag(0) and 2.8 +/- 0.4 nm Pt(0)) in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (BMI x (NTf)2) with a syrup of cellulose acetate (CA) in acetone. The presence of small and stable Au(0), Ag(0) or Pt(0) nanoparticles induced an augmentation in the CA/IL film surface areas. The addition of the IL to the membrane resulted in an increase of its elasticity and a decrease in its tenacity and toughness, whereas its stress at break was not influenced. High antimicrobial activity was observed in membranes containing Au(0), Ag(0) and Pt(0) metal concentrations as low as 1 mg of metal per 5 g of CA. The CA/IL/nanoparticle combination enhanced the activity and durability of the metal nanoparticles and provided greater antimicrobial activity against E. coli and S. aureus bacteria. PMID:21770152

Scheeren, Carla W; Hermes, Vanessa; Bianchi, Otávio; Hertz, Plinho F; Dias, Silvio L P; Dupont, Jairton

2011-06-01

327

Ionic liquid-mediated extraction of lipids from algal biomass.  

PubMed

Lipids from algal biomass were extracted using mixtures of ionic liquids (ILs) and methanol, and fatty acid profiles of the extracted lipids were characterized in this work. Mixtures of ILs and methanol successfully dissolved biomass leaving lipids insoluble. The total contents of lipids extracted from commercial and cultivated Chlorella vulgaris were 10.6% and 11.1%, respectively, by the conventional Bligh and Dyer's method, while a mixture of [Bmim][CF(3)SO(3)] and methanol extracted 12.5% and 19.0% of the lipids, respectively. Multi-parameter regression by the linear solvation energy relationship showed that dipolarity/polarizability and hydrogen bond acidity of ILs are more important than their hydrogen bond basicity for effectively extracting lipids from algal biomass. Fatty acid profiles of the lipids extracted using IL-methanol mixtures showed that C16:0, C16:1, C18:2, and C18:3 fatty acids were dominant. This suggests that the lipids extracted from C. vulgaris can be used as a source of biodiesel production. PMID:21601447

Kim, Young-Hoo; Choi, Yong-Keun; Park, Jungsu; Lee, Seongmin; Yang, Yung-Hun; Kim, Hyung Joo; Park, Tae-Joon; Hwan Kim, Yong; Lee, Sang Hyun

2011-05-01

328

Sublethal Ionic Liquid Concentrations Alter Grazer-Periphyton Interactions  

NASA Astrophysics Data System (ADS)

Ionic liquids (ILs) are non-volatile organic salts that are considered environmentally-friendly replacements for volatile organic compounds. While ILs will not pollute the atmosphere, they could enter aquatic ecosystems and negatively affect communities and ecosystem processes. To determine if the IL, 1-methyl-3-butylimidazolium bromide (bmimBr), affected grazer-periphyton interactions, we factorially crossed 4 levels of bmimBr (0, 1, 10, and 100 mg/L1) with the presence or absence of the snail, Physa acuta, in laboratory experiments. After 14 days, all bmimBr concentrations reduced chlorophyll a (chl a) abundance by 35-49% relative to controls lacking bmimBr. Algal biovolume also declined by 65-85% at 10 and 100 mg/L1 bmimBr relative to controls. When both bmimBr and snails were present, chl a abundance and algal biovolume were higher than expected if both factors acted additively, suggesting that snails were less efficient grazers in the presence of bmimBr. Furthermore, snail growth rates declined by 41-101% at 10 and 100 mg/L1 bmimBr relative to controls. At the ecosystem level, snails stimulated periphyton primary production in the absence of bmimBr, suggesting that bmimBr can indirectly alter ecosystem processes. Our research shows that sublethal levels of an IL can negatively impact aquatic communites and ecosystem processes via complex trophic interactions.

Evans-White, M. A.; Lamberti, G. A.

2005-05-01

329

Pretreatment and fractionation of wheat straw using various ionic liquids.  

PubMed

Pretreatment of lignocellulosic biomass with ionic liquids (ILs) is a promising and challenging process for an alternative method of biomass processing. The present work emphasizes the examination of wheat straw pretreatment using ILs, namely, 1-butyl-3-methylimidazolium hydrogensulfate ([bmim][HSO4]), 1-butyl-3-methylimidazolium thiocyanate ([bmim][SCN]), and 1-butyl-3-methylimidazolium dicyanamide ([bmim][N(CN)2]). Only [bmim][HSO4] was found to achieve a macroscopic complete dissolution of wheat straw during pretreatment. The fractionation process demonstrated to be dependent on the IL used. Using [bmim][SCN], a high-purity lignin-rich material was obtained. In contrast, [bmim][N(CN)2] was a good solvent to produce high-purity carbohydrate-rich fractions. When [bmim][HSO4] was used, a different behavior was observed, exhibiting similarities to an acid hydrolysis pretreatment, and no hemicellulose-rich material was recovered during fractionation. A capillary electrophoresis (CE) technique allowed for a better understanding of this phenomenon. Hydrolysis of carbohydrates was confirmed, although an extended degradation of monosaccharides to furfural and hydroxymethylfurfural (HMF) was observed. PMID:23876219

da Costa Lopes, André M; João, Karen G; Bogel-?ukasik, Ewa; Roseiro, Luísa B; Bogel-?ukasik, Rafa?

2013-08-07

330

Molecular beam deposition of nanoscale ionic liquids in ultrahigh vacuum.  

PubMed

We propose a new approach to nanoscience and technology for ionic liquids (ILs): molecular beam deposition of IL in ultrahigh vacuum by using a continuous wave infrared (CW-IR) laser deposition technique. This approach has made it possible to prepare a variety of "nano-IL" with the given composition on the substrate: a nanodroplet, on one hand, the volume of which goes down to 1 aL and, on the other hand, an ultrathin film with a thickness to several 100 nm or less. The result of fractional distillation of a binary mixture of ILs, investigated by nuclear magnetic resonance as well as electrospray ionization time-of-flight mass spectrometry, indicates that this deposition process is based on the thermal evaporation of ILs, and thus this process also can be used as a new purification method of ILs in vacuum. Furthermore, the fabrication of binary mixture droplets of two ILs on the substrate by alternating deposition of two ILs was demonstrated; the homogeneity of the composition was confirmed even for one single droplet by high-spatial-resolution Raman spectroscopy. PMID:20863104

Maruyama, Shingo; Takeyama, Yoko; Taniguchi, Hiroki; Fukumoto, Hiroki; Itoh, Mitsuru; Kumigashira, Hiroshi; Oshima, Masaharu; Yamamoto, Takakazu; Matsumoto, Yuji

2010-10-26

331

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

332

Microwave-assisted functionalization of carbon nanostructures in ionic liquids.  

PubMed

The effect of microwave (MW) irradiation and ionic liquids (IL) on the cycloaddition of azomethine ylides to [60]fullerene has been investigated by screening the reaction protocol with regard to the IL medium composition, the applied MW power, and the simultaneous cooling of the system. [60]Fullerene conversion up to 98 % is achieved in 2-10 min, by using a 1:3 mixture of the IL 1-methyl-3-n-octyl imidazolium tetrafluoroborate ([omim]BF(4)) and o-dichlorobenzene, and an applied power as low as 12 W. The mono- versus poly-addition selectivity to [60]fullerene can be tuned as a function of fullerene concentration. The reaction scope includes aliphatic, aromatic, and fluorous-tagged (FT) derivatives. MW irradiation of IL-structured bucky gels is instrumental for the functionalization of single-walled carbon nanotubes (SWNTs), yielding group coverages of up to one functional group per 60 carbon atoms of the SWNT network. An improved performance is obtained in low viscosity bucky gels, in the order [bmim]BF(4)> [omim]BF(4)> [hvim]TF(2)N (bmim=1-methyl-3-n-butyl imidazolium; hvim=1-vinyl-3-n-hexadecyl imidazolium). With this protocol, the introduction of fluorous-tagged pyrrolidine moieties onto the SWNT surface (1/108 functional coverage) yields novel FT-CNS (carbon nanostructures) with high affinity for fluorinated phases. PMID:19847823

Guryanov, Ivan; Toma, Francesca Maria; Montellano López, Alejandro; Carraro, Mauro; Da Ros, Tatiana; Angelini, Guido; D'Aurizio, Eleonora; Fontana, Antonella; Maggini, Michele; Prato, Maurizio; Bonchio, Marcella

2009-11-23

333

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

334

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

335

Thermoresponsive Polymers and Block Copolymers in Ionic Liquids  

NASA Astrophysics Data System (ADS)

We recently discovered that poly(ethylene oxide) (PEO) and poly(n-butyl methacrylate) (PnBMA) exhibit two completely different types of lower critical solution temperature (LCST) phase behavior in certain ionic liquids (ILs). While typical LCST type phase diagrams were shown in PnBMA/IL systems, we observed unusual temperature-composition phase diagrams in the PEO/IL systems, in which the cloud point curves are strongly asymmetric, with the critical composition located at 80 wt % of PEO. In addition, an important feature of these thermosensitive polymer/IL systems is that the LCST can be easily tuned over a wide range by blending different ILs, without changing the chemical structure of the polymers. On the basis of the LCST of PEO and the upper critical solution temperature (UCST) of poly(N-isopropylacrylamide) (PNIPAm) in ILs, we designed a PEO-PNIPAm block copolymer that exhibits interesting doubly thermosensitive self-assembly. The block copolymer forms PNIPAm-core micelles at low temperatures and transforms into PEO-core micelles at high temperatures. The critical micellization temperatures (CMT) of both blocks can be manipulated by adjusting the mixing ratio of ILs.

Lee, Hau-Nan; Bai, Zhifeng; Newell, Nakisha; Lodge, Timothy

2011-03-01

336

Acetylation of alpha-chitin in ionic liquids.  

PubMed

Acetylation of alpha-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 degrees C for 24h for dissolution. Then, acetic anhydride (5-20 equiv) was added to the solution and the mixture was heated with stirring at desired temperatures for 24h. The product was precipitated by the addition of the reaction mixture into methanol. The IR spectrum of the product indicated the progress of acetylation. The degrees of substitution (DS), which were determined from the IR spectra, increased with increasing the amounts of acetic anhydride used for the reaction. The highest DS was 1.86, which was obtained by the reaction using 20 equiv of acetic anhydride at 100 degrees C. The product with this DS value was soluble in DMSO, and thus the structure of the product was further confirmed by (1)H NMR spectroscopy in DMSO-d(6). The DS value estimated by the integrated ratio of signals due to acetyl protons to a signal due to anomeric protons was in good agreement with that determined from the IR spectrum. PMID:19732868

Mine, Shozaburo; Izawa, Hironori; Kaneko, Yoshiro; Kadokawa, Jun-Ichi

2009-08-08

337

EFFECTS OF GAMMA RADIATION ON ELECTROCHEMICAL PROPERTIES OF IONIC LIQUIDS  

SciTech Connect

The electrochemical properties of ionic liquids (ILs) make them attractive for possible replacement of inorganic salts in high temperature molten salt electrochemical processing of nuclear fuel. To be a feasible replacement solvent, ILs need to be stable in moderate and high doses of radiation without adverse chemical and physical effects. Here, we exposed seven different ILs to a 1.2 MGy dose of gamma radiation to investigate their physical and chemical properties as they related to radiological stability. The azolium-based ILs experienced the greatest change in appearance, but these ILs were chemically more stable to gamma radiation than some of the other classes of ILs tested, due to the presence of aromatic electrons in the azolium ring. All the ILs exhibited a decrease in their conductivity and electrochemical window (at least 1.1 V), both of which could affect the utility of ILs in electrochemical processing. The concentration of the irradiation decomposition products was less than 3 mole %, with no impurities detectable using NMR techniques.

Visser, A; Nicholas Bridges, N; Thad Adams, T; John Mickalonis, J; Mark02 Williamson, M

2009-04-21

338

Reversible capture of SO2 through functionalized ionic liquids.  

PubMed

Emission of SO2 in flue gas from the combustion of fossil fuels leads to severe environmental problems. Exploration of green and efficient methods to capture SO2 is an interesting topic, especially at lower SO2 partial pressures. In this work, ionic liquids (ILs) 1-(2-diethylaminoethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Et2 NEMim][Tf2 N]) and 1-(2-diethylaminoethyl)-3-methylimidazolium tetrazolate ([Et2 NEMim][Tetz]) were synthesized. The performances of the two ILs to capture SO2 were studied under different conditions. It was demonstrated that the ILs were very efficient for SO2 absorption. The [Et2 NEMim][Tetz] IL designed in this work could absorb 0.47 g(SO2)g(IL)(-1) at 0.0101 MPa SO2 partial pressure, which is the highest capacity reported to date under the same conditions. The main reason for the large capacity was that both the cation and the anion could capture SO2 chemically. In addition, the IL could easily be regenerated, and the very high absorption capacity and rapid absorption/desorption rates were not changed over five repeated cycles. PMID:23681974

Yang, Dezhong; Hou, Minqiang; Ning, Hui; Ma, Jun; Kang, Xinchen; Zhang, Jianling; Han, Buxing

2013-05-16

339

Reversible electro-optic device employing aprotic molten salts and method  

Microsoft Academic Search

A single-compartment reversible mirror device having a solution of aprotic molten salt, at least one soluble metal-containing species comprising metal capable of being electrodeposited, and at least one anodic compound capable of being oxidized was prepared. The aprotic molten salt is liquid at room temperature and includes lithium and\\/or quaternary ammonium cations, and anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-),

Benjamin P. Warner; T. Mark McCleskey; Anthony K. Burrell; Simon B. Hall

2008-01-01

340

Gold-catalyzed hydrative cyclization of 1,6-diynes in ionic liquid media  

Microsoft Academic Search

Gold-catalyzed hydrative cyclization of terminal 1,6-diynes proceeds in ionic liquid with methanol as co-solvent. The solvent-catalyst could be recycled, after separation of the product by extraction with ether.

Dong-Mei Cui; Yi-Na Ke; Dan-Wen Zhuang; Qian Wang; Chen Zhang

2010-01-01

341

Life Cycle Assessment of an Ionic LIquid versus Traditional Solvents and Their Applications  

EPA Science Inventory

Ionic liquids (ILs) have been claimed as "greener" replacements to traditional solvents. HOwever, the environmental impacts of the life cycle phases including the making of ILs, their application, separation, etc., and comparison with alternative methods have not been studied. Su...

342

Critical cellulase and hemicellulase activities for hydrolysis of ionic liquid pretreated biomass  

Technology Transfer Automated Retrieval System (TEKTRAN)

Critical cellulase and hemicellulase activities are identified for hydrolysis of ionic liquid (IL) pretreated poplar and switchgrass; hemicellulase rich substrates with amorphous cellulose. Enzymes from Aspergillus nidulans were expressed and purified: an endoglucanase (EG) a cellobiohydrolase (CBH)...

343

Formation of ?-caprolactam via catalytic Beckmann rearrangement using P 2O 5 in ionic liquids  

Microsoft Academic Search

Catalytic Beckmann rearrangement of cyclohexanone oxime in ionic liquids using P2O5 or Eaton's reagent has been investigated. 1-n-Butyl-3-methylimidazolium hexafluorophosphate (bmiPF6) gives superior results to those noted by earlier workers.

Rex X Ren; Larisa D Zueva; Wei Ou

2001-01-01

344

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

345

First volatility study of the 1-alkylpyridinium based ionic liquids by Knudsen effusion  

NASA Astrophysics Data System (ADS)

For the first time, a volatility study of the 1-ethylpyridinium bis(trifluoromethylsulfonyl)imide ([C2Py][NTf2], CAS: 712354-97-7), 1-propylpyridinium bis(trifluoromethylsulfonyl)imide ([C3Py][NTf2]) and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide ([C4Py][NTf2], CAS: 187863-42-9) ionic liquids, is presented. The vapor pressures as a function of temperature, for this ionic liquids were measured and the thermodynamic properties of vaporization were derived. The analysis and rationalization of the obtained results for the alkylpyridinium based ionic liquids was done based on the comparison with the [CN-1C1im][NTf2] (N = 3-5). The volatility of pyridinium is five times lower than the imidazolium based ionic liquids and that is driven by their higher enthalpy of vaporization.

Rocha, Marisa A. A.; Santos, Luís M. N. B. F.

2013-10-01

346

Properties of the Nafion membrane impregnated with hydroxyl ammonium based ionic liquids  

NASA Astrophysics Data System (ADS)

In this work, the Nafion 112 membrane impregnated with nine various hydroxyl ammonium based ionic liquids have been investigated. The used ionic liquids were combined from hydroxyl ammonium cations (2-hydroxyethylammonium/HEA, bis(2- hydroxyethyl)ammonium/BHEA, tris(2-hydroxyethyl)ammonium/THEA) and carboxylate anions (formate, acetate, lactate). The membranes are characterized by conductivity and thermal stability measurements. It was found, that almost all composites have 10 times higher ion conductivity than a pure Nafion 112 at 90 °C in ambient environment due to the higher thermal stability. The thermal stability of Nafion membrane was increased by all studied nine ionic liquids. In this work, only biodegradable ionic liquids were used for composite preparation.

Garaev, Valeriy; Kleperis, Janis; Pavlovica, Sanita; Vaivars, Guntars

2012-08-01

347

Direct conversion of glucose and cellulose to 5-hydroxymethylfurfural in ionic liquid under microwave irradiation  

Microsoft Academic Search

An efficient strategy for CrCl3-mediated production of 5-hydroxymethylfurfural (HMF) in ca. 60% and 90% isolated yields from cellulose and glucose, respectively, in ionic liquid under microwave irradiation is presented.

Changzhi Li; Zehui Zhang; Zongbao K. Zhao

2009-01-01

348

Exothermic and thermal runaway behaviour of some ionic liquids at elevated temperatures.  

PubMed

The exothermic behaviour and intrinsic safety of a number of ionic liquids being considered for battery and solar cell applications have been investigated at elevated temperatures by analysing data from accelerated rate calorimetric (ARC) studies. PMID:19826700

Vijayaraghavan, R; Surianarayanan, M; Armel, V; MacFarlane, D R; Sridhar, V P

2009-09-07

349

Novel Ionic Liquid with Both Lewis and Br?nsted Acid Sites for Michael Addition  

PubMed Central

Ionic liquid with both Lewis and Brønsted acid sites has been synthesized and its catalytic activities for Michael addition were carefully studied. The novel ionic liquid was stable to water and could be used in aqueous solution. The molar ratio of the Lewis and Brønsted acid sites could be adjusted to match different reactions. The results showed that the novel ionic liquid was very efficient for Michael addition with good to excellent yields within several min. Operational simplicity, high stability to water and air, small amount used, low cost of the catalyst used, high yields, chemoselectivity, applicability to large-scale reactions and reusability are the key features of this methodology, which indicated that this novel ionic liquid also holds great potential for environmentally friendly processes.

Jiang, Xiaoyue; Ye, Weidong; Song, Xiaohua; Ma, Wenxin; Lao, Xuejun; Shen, Runpu

2011-01-01

350

Development of the Electrochemical Biosensor for Organophosphate Chemicals Using CNT/Ionic Liquid Bucky Gel Electrode.  

National Technical Information Service (NTIS)

Organophosphorus hydrolase (OPH) immobilized on CNT/ionic liquid (IL) electrodes were prepared by using three different intrinsic kinds of ILs, as binders. CNTs/ILs lead to dramatic electrochemical enhancements with respect to response time, stability, an...

B. G. Choi D. H. Kim H. Park S. Y. Lee T. J. Park

2010-01-01

351

DESIGN AND EVALUATION OF IONIC LIQUIDS AS NOVEL CO2 ABSORBENTS  

SciTech Connect

Progress from the first quarter of activity on the project ''Design and Evaluation of Ionic Liquids as Novel CO{sub 2} Absorbents'' is provided. Major activities in three areas are reported: ''assembling equipment and a research team, compound synthesis and molecular modeling''. Nine new ionic liquid compounds have been made or acquired, and are in line for physical property testing to assess their potential for CO{sub 2} sequestration. Quantum mechanical calculations between CO{sub 2} and different ionic liquids have been conducted. The simulations have shed light on the nature of interactions between CO{sub 2} and the ionic liquids, and are providing insight that will be used to suggest new compounds to be synthesized and tested.

Edward J. Maginn

2004-12-31

352

Reversible Ionic Liquids as Double-Action Solvents for Efficient CO2 Capture.  

National Technical Information Service (NTIS)

We have developed a novel class of CO2 capture solvents, Reversible Ionic Liquids (RevILs), that offer high absorption capacity through two modes of capture: chemical reaction (chemisorption) and physical solubility (physisorption). These solvents are sil...

C. A. Eckert C. L. Liotta

2011-01-01

353

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

354

Carbon dioxide separation through supported ionic liquids membranes in polymeric matrixes  

SciTech Connect

As compared to other gas separation techniques, membranes have several advantages which can include low capital cost, relatively low energy usage and scalability. While it could be possible to synthesize the ideal polymer for membrane separation of carbon dioxide from fuel gas, it would be very intensive in terms of money and time. Supported liquid membranes allow the researcher to utilize the wealth of knowledge available on liquid properties. Ionic liquids, which can be useful in capturing CO2 from fuel gas because they posses high CO2 solubility in the ionic liquid relative to H2, are an excellent candidate for this type of membrane. Ionic liquids are not susceptible to evaporation due to their negligible vapor pressure and thus eliminate the main problem typically seen with supported liquid membranes. A study has been conducted evaluating the use of the ionic liquid 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, the ionic liquid was synthesized and characterized at the University of Notre Dame, incorporated into a polymeric matrix, and tested at the National Energy Technology Laboratory. Initial results have been very promising with calculated CO2 permeabilities as high as 950 barrers and significant improvements in CO2/H2 selectivity over the unmodified polymer at 37 oC along with promising results at elevated temperatures. In addition to performance, the study included examining the choice of polymeric supports on performance and membrane stability in more realistic operating conditions. Also included in this study was an evaluation of novel approaches to incorporate the ionic liquid into polymer matrices to optimize the performance and stability of the membranes.

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

2006-09-01

355

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

356

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

357

Fabrication of polyaniline–silver nanocomposites by chronopotentiometry in different ionic liquid microemulsion systems  

Microsoft Academic Search

Chronopotentiometry is employed to prepare polyaniline–silver (PANI–Ag) nanocomposite films in water-in-ionic liquid (W\\/IL) microemulsion and ionic liquid-in-water (IL\\/W) microemulsion. The resulted nanocomposites are characterized by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction. It is demonstrated that the PANI–Ag nanocomposite prepared in W\\/IL microemulsion is nanofibrous and the Ag nanocrystals with 5 nm diameter are dispersed

Zhou Zhou; Deliang He; Yanni Guo; Zhengdan Cui; Minghao Wang; Guoxi Li; Ronghua Yang

2009-01-01

358

Determining relative rates of cellulose dissolution in ionic liquids through in situ viscosity measurement.  

PubMed

Using in situ viscosity measurement, the rate of cellulose dissolution in a number of ionic liquids has been determined allowing their performance as solvents to be quantitatively assessed. 1-Butyl-3-methylimidazolium ethanoate was shown to dissolve cellulose faster than analogous ionic liquids with chloride or dimethylphosphate anions. Analysis of the data highlights the influence of both anion basicity and relative concentration on the rate of dissolution. PMID:22531832

Cruz, Hugo; Fanselow, Markus; Holbrey, John D; Seddon, Kenneth R

2012-04-24

359

Visualization of biomass solubilization and cellulose regeneration during ionic liquid pretreatment of switchgrass  

Microsoft Academic Search

Auto-fluorescent mapping of plant cell walls was used to visualize cellulose and lignin in pristine switchgrass (Panicum virgatum) stems to determine the mechanisms of biomass dissolution during ionic liquid pretreatment. The addition of ground switchgrass to the ionic liquid 1-n-ethyl-3-methylimidazolium acetate resulted in the disruption and solubilization of the plant cell wall at mild temperatures. Swelling of the plant cell

Seema Singh; Blake A. Simmons; Kenneth P. Vogel

2009-01-01

360

A convenient synthesis of triflate anion ionic liquids and their properties.  

PubMed

A solvent- and halogen-free synthesis of high purity triflate ionic liquids via direct alkylation of organic bases (amines, phosphines or heterocyclic compounds) with methyl and ethyl trifluoromethanesulfonate (methyl and ethyl triflate) has been developed. Cheap and non-toxic dimethyl and diethyl carbonate serve as source for the methyl and ethyl groups in the preparation of methyl and ethyl triflate by this invented process. The properties of ionic liquids containing the triflate anion are determined and discussed. PMID:22565482

Ignat'ev, Nikolai V; Barthen, Peter; Kucheryna, Andryi; Willner, Helge; Sartori, Peter

2012-05-07

361

An experimental study of gas transport and separation properties of ionic liquids supported on nanofiltration membranes  

Microsoft Academic Search

Permeability of gas molecules H2, O2, N2, and CO in four types of ionic liquids ([C4-mim][NTf2], [C10-mim][NTf2], [N8881][NTf2], [C8Py][NTf2]) with a common anion but different cations supported on nanofiltration membranes was studied in single gas feed and under varying gas phase pressure. The separation property in terms of H2\\/CO selectivity in the selected ionic liquids was examined in binary gas

Quan Gan; David Rooney; Minliang Xue; Gillian Thompson; Yiran Zou

2006-01-01

362

Anion effects in imidazolium ionic liquids on the performance of IPMCs  

Microsoft Academic Search

Four ionic liquids were explored for as inner solvents of IPMC to overcome the shortcomings of water, especially its high volatility and low electrolysis potential. The imidazolium salts were composed of 1-ethyl-3-methylimidazolium [EMIm] cation and anions including bromide [Br], nitrate [NO3], acetate [AcO], and trifluoroacetate [TA]. The 1H NMR studies confirmed the structures of the four ionic liquids and indicated

Jang-Woo Lee; Young-Tai Yoo

2009-01-01

363

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

364

Organic Reactions in Ionic Liquids: Gewald Synthesis of 2?Aminothiophenes Catalyzed by Ethylenediammonium Diacetate  

Microsoft Academic Search

Ionic liquids based on 1?butyl?3?methylimidazolium tetrafluoroborate (BmimBF4) and 1?butyl?3?methylimidazolium hexafluorophosphate (BmimPF6) were used as reusable alternatives to volatile organic solvents (VOCs) for ethylenediammonium diacetate (EDDA) catalyzed Gewald synthesis of 2?aminothiophenes. Significant rate enhancement and improvement of the yield were observed. The ionic liquids containing catalyst EDDA were recycled several times with no decreases in yields and reaction rates.

Yi Hu

2004-01-01

365

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

366

Electrochemical activity of glucose oxidase on a poly(ionic liquid) - Au nanoparticle composite.  

SciTech Connect

Glucose oxidase (GOx) adsorbed on an ionic liquid-derived polymer containing internally organized columns of Au nanoparticles exhibits direct electron transfer and bioelectrocatalytic properties towards the oxidation of glucose. The cationic poly(ionic liquid) provides an ideal substrate for the electrostatic immobilization of GOx. The encapsulated Au nanoparticles serve to both promote the direct electron transfer with the recessed enzyme redox centers and impart electronic conduction to the composite, allowing it to function as an electrode for electrochemical detection.

Lee, S.; Ringstrand, B. S.; Stone, D. A.; Firestone, M. A. (Materials Science Division)

2012-01-01

367

Synthesis of Dehydroabietic Acid (2-Acryloyloxy) Ethyl Ester in Ionic Liquids  

Microsoft Academic Search

A simple ionic liquid methodology for the synthesis of a novel derivative of dehydroabietic acid is described. 1-Butyl-3-methylimidazolium tetrafluoroborate [bmim]BF4, a typical ionic liquid, was used as an efficient and environmentally benign solvent in the synthesis of dehydroabietic acid (2-acryloloxy) ethyl ester by O-acylation reaction of dehydroabietic acid chloride with 2-hydroxyethyl acrylate. This new method showed the advantages of mild

Xuetang Xu; Wengui Duan; Qinghua Peng; Liumei Qin; Guanghua Li; Xiongmin Liu

2009-01-01

368

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

369

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

370

An efficient catalytic dehydration of fructose and sucrose to 5-hydroxymethylfurfural with protic ionic liquids  

Microsoft Academic Search

The renewable furan-based platform chemical, 5-hydroxymethylfurfural (HMF), has been efficiently synthesized from d-fructose and sucrose in the presence of a catalytic amount of protic ionic liquids. The 1-methylimidazolium-based and N-methylmorpholinium-based ionic liquids are employed. As a result, 74.8% and 47.5% yields of HMF are obtained from d-fructose and sucrose, respectively, at 90°C for 2h under nitrogen atmosphere when N-methylmorpholinium methyl

Xinli Tong; Yang Ma; Yongdan Li

2010-01-01

371

Novel dehydration of carbohydrates to 5-hydroxymethylfurfural catalyzed by Ir and Au chlorides in ionic liquids  

Microsoft Academic Search

Catalytic dehydration of carbohydrates into 5-hydroxymethylfurfural (5-HMF) has been studied in the presence of ionic liquids, i.e., 1-butyl-3-methyl imidazolium chloride ([BMIM]Cl) and triethylamine sulphate ([Et3NH][HSO4]) using metal salts as catalysts. Novel metal chlorides IrCl3 and AuCl3·HCl as catalysts in ionic liquid showed remarkable activity and selectivity to 5-HMF for the reaction of fructose dehydration. The reaction conditions of fructose dehydration

Zuojun Wei; Yan Li; Dilantha Thushara; Yingxin Liu; Qilong Ren

2011-01-01

372

Novel Basic Ionic Liquid Based on Alkylammonium as Efficient Catalyst for Knoevenagel Reaction  

Microsoft Academic Search

The typical Knoevenagel condensation was carried out smoothly in the presence of a basic ionic liquid of N,N,N?,N?-tetramethyl-N?-hexyl-ethylenediammonium tetrafluoroborate ([TMHEDA]BF4), and 99% of yield was obtained using ethyl cyanoacetate and benzaldehyde as substrates at 60 °C for 1 h. Four reuses of the ionic liquid without dramatic decrease in catalytic activity for Knoevenagel condensation demonstrated the good stability and operability of the

Shuai Zhou; Lu Liu; Bo Wang; Mingguo Ma; Feng Xu; Runcang Sun

2012-01-01

373

Novel Basic Ionic Liquid Based on Alkylammonium as Efficient Catalyst for Knoevenagel Reaction  

Microsoft Academic Search

The typical Knoevenagel condensation was carried out smoothly in the presence of a basic ionic liquid of N,N,N’,N’-tetramethyl-N’-hexyl-ethylenediammonium tetrafluoroborate ([TMHEDA]BF4), and 99% of yield was obtained using ethyl cyanoacetate and benzaldehyde as substrates at 60 °C for 1 h. Four times reuse of the ionic liquid without dramatic decrease in catalytic activity to Knoevenagel condensation demonstrated the good stability and operability of

Shuai Zhou; Bo Wang; Mingguo Ma; Feng Xu; Runcang Sun

2011-01-01

374

Influence of Imidazolium Ionic Liquids on Dehydrogenase Activity of Activated Sludge Microorganisms  

Microsoft Academic Search

Imidazolium salts are one of the most often used and investigated groups of ionic liquids (ILs). The research concerning their\\u000a ecotoxicity comprised many test organisms representing different trophic levels; however, their impact on mixed cultures of\\u000a microorganisms such as activated sludge has been hardly ever investigated. Thus, in this work, the effect of imidazolium ionic\\u000a liquids on dehydrogenase activity of

Ewa Liwarska-Bizukojc

375

Ionic liquid-nanoparticle hybrid electrolytes and their application in secondary lithium-metal batteries.  

PubMed

Ionic liquid-tethered nanoparticle hybrid electrolytes comprised of silica nanoparticles densely grafted with imidazolium-based ionic liquid chains are shown to retard lithium dendrite growth in rechargeable batteries with metallic lithium anodes. The electrolytes are demonstrated in full cell studies using both high-energy Li/MoS(2) and high-power Li/TiO(2) secondary batteries. PMID:22786760

Lu, Yingying; Das, Shyamal K; Moganty, Surya S; Archer, Lynden A

2012-07-12

376

Oxidation of unsaturated compounds in ionic liquids with the use of cyclodextrin-containing catalytic systems  

Microsoft Academic Search

The Wacker oxidation of alkenes-1 in ionic liquids catalyzed by a system containing palladium, and copper complexes and ?-cyclodextrins\\u000a was studied. It was shown that the use of ?-cyclodextrins substantially increases the oxidation rate in biphasic systems olefin\\/ionic\\u000a liquid. It was found that the proposed catalytic systems possess substrate selectivity, which is determined by the structure\\u000a of a receptor molecule.

L. V. Andreeva; A. L. Maksimov; A. Ya. Zhuchkova; V. V. Predeina; T. Yu. Filippova; E. A. Karakhanov

2007-01-01

377

Remove Olefin from Diesel Oil with Chloroaluminate(III) Ionic Liquids  

Microsoft Academic Search

Ionic liquids are low-melting-point salts that represent an exciting new class of reaction solvents. In this article, the author mainly refers to the effects of the olefin removal in the diesel oil using [bmim]Br-AlCl3 (where [bmim] is 1-butyl-3-methylimidazolium cation) ionic liquid. The result shows the better performance in the olefin removal. Therefore, an environmental friendly approach for olefin removal from

D.-J. Qiao; L. Shi

2010-01-01

378

Direct measurements of ionic mobility of ionic liquids using the electric field applying pulsed gradient spin-echo NMR.  

PubMed

Ionic mobilities of the ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide,1-ethyl-3-methylimidazolium fluorosulfonyl-(trifluoromethylsulfonyl)amide, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) -amide, were measured using the electric field applying pulsed gradient spin-echo NMR technique. Observed mobilities were more than 1 order of magnitude greater than the values estimated from the diffusion coefficients measured under the equilibrium state without the electric field. Electric field dependence of the ionic mobility showed that the high mobility appeared above the threshold of the field strength with keeping the constant values. This indicates that the ions are orientated by the application of the electric field may be due to the dielectric polarization. PMID:19496553

Umecky, Tatsuya; Saito, Yuria; Matsumoto, Hajime

2009-06-25

379

Understanding the evaporation of ionic liquids using the example of 1-ethyl-3-methylimidazolium ethylsulfate.  

PubMed

In this work we present a comprehensive temperature-dependence analysis of both the structural and the dynamic properties of a vaporized ionic liquid (1-ethyl-3-methylimidazolium ethylsulfate). This particular ionic liquid is known to be distillable from experimental studies and thus enables us to deepen the understanding of the evaporation mechanism of ionic liquids. We have used ab initio molecular dynamics of one ion pair at three different temperatures to accurately describe the interactions present in this model ionic liquid. By means of radial and spatial distribution functions a large impact on the coordination pattern at 400 K is shown which could explain the transfer of one ion pair from the bulk to the gas phase. Comparison of the free energy surfaces at 300 K and 600 K supports the idea of bulk phase-like and gas phase-like ion pairs. The different coordination patterns caused by the temperature, describing a loosening of the anion side chains, are also well reflected in the power spectra. The lifetime analysis of typical conformations for ionic liquids shows a characteristic behavior at 400 K (temperature close to the experimental evaporation temperature), indicating that conformational changes occur when the ionic liquid is evaporated. PMID:24037209

Malberg, Friedrich; Brehm, Martin; Hollóczki, Oldamur; Pensado, Alfonso S; Kirchner, Barbara

2013-10-01

380

Solubilization of an Ionic Liquid, l-Butyl-3-methylimidazolium Hexafluorophosphate, in a Surfactant-Water System  

Microsoft Academic Search

The amphiphilic association structures were determined in the system; water, Laureth 4 (approximately C12(EO) 4), and the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate ([bmim[PF6]), using visual observation and small angle x-ray diffraction. The system showed a lamellar liquid crystal solubilizing the ionic liquid ([bmim[PF6]) to a maximum of 15%, an isotropic surfactant solution dissolving the ionic liquid to a maximum of 39%,

Stig E. Friberg; Qi Yin; Florentina Pavel; Raymond A. Mackay; John D. Holbrey; Kenneth R. Seddon; Patricia A. Aikens

2000-01-01

381

Dicationic versus monocationic ionic liquids: distinctive ionic dynamics and dynamical heterogeneity.  

PubMed

The dynamical properties of a dicationic ionic liquid (IL), 1,6-bis(3-methylimidazolium-1-yl)hexane bis(trifluoromethylsulfonyl)amide ([C(6)(MIm)(2)][NTf(2)](2)), compared to 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)amide ([C(3)MIm][NTf(2)]), as its monocationic imidazolic counterpart, are studied by molecular dynamics simulations. We investigate relaxation processes of the polarizability anisotropy of the system and collective dynamics of both the ILs with mean-squared displacement (MSD), non-Gaussian parameter, and the intermediate scattering functions. The analyses of librational dynamics show that the difference of the Kerr spectra between the ILs could be mainly ascribed to the distinctive angular momentum of [C(6)(MIm)(2)](2+) and [C(3)MIm](+) and related to the difference of relaxation behavior between [C(6)(MIm)(2)](2+) and [C(3)MIm](+). Also, it is indicated that the librational dynamics of [NTf(2)](-) indicate a common resonance-type sharp peak that corresponds to an intermolecular motion coupled to the vibrational mode intrinsic to [NTf(2)](-). In addition, it is exhibited from the total X-ray structure factors calculated for both of the ILs that the low-k peak at 0.20 Å(-1) appears for [C(6)(MIm)(2)][NTf(2)](2), while we do not see it for [C(3)MIm][NTf(2)]. We find that the contribution of the anion-cation and anion-anion correlations to the low-k peak is more significant than the cation-cation correlation. Therefore, it is suggested for [C(6)(MIm)(2)][NTf(2)](2) that dynamical heterogeneous behavior strongly correlates with structural variations or heterogeneity. PMID:23272700

Ishida, Tateki; Shirota, Hideaki

2013-01-15

382

Sonochemistry and sonoluminescence in ionic liquids, molten salts, and concentrated electrolyte solutions  

Microsoft Academic Search

Ionic liquids have favorable intrinsic properties that make them of\\u000a interest as solvents for various chemical reactions. The same properties\\u000a that make the liquids effective solvents also make them interesting\\u000a liquids for studies involving sonochemistry, acoustic cavitation, and\\u000a sonoluminescence. Recent interest in using ultrasound to accelerate\\u000a chemical reactions conducted in ionic liquids necessitates an\\u000a understanding of the effects of acoustic

David J. Flannigan; Stephen D. Hopkins; Kenneth S. Suslick

2005-01-01

383

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

384

Groove binding mechanism of ionic liquids: a key factor in long-term stability of DNA in hydrated ionic liquids?  

PubMed

Nucleic acid sample storage is of paramount importance in biotechnology and forensic sciences. Very recently, hydrated ionic liquids (ILs) have been identified as ideal media for long-term DNA storage. Hence, understanding the binding characteristics and molecular mechanism of interactions of ILs with DNA is of both practical and fundamental interest. Here, we employ molecular dynamics simulations and spectroscopic experiments to unravel the key factors that stabilize DNA in hydrated ILs. Both simulation and experimental results show that DNA maintains the native B-conformation in ILs. Simulation results further suggest that, apart from the electrostatic association of IL cations with the DNA backbone, groove binding of IL cations through hydrophobic and polar interactions contributes significantly to DNA stability. Circular dichroism spectral measurements and fluorescent dye displacement assay confirm the intrusion of IL molecules into the DNA minor groove. Very interestingly, the IL ions were seen to disrupt the water cage around DNA, including the spine of hydration in the minor groove. This partial dehydration by ILs likely prevents the hydrolytic reactions that denature DNA and helps stabilize DNA for the long term. The detailed understanding of IL-DNA interactions provided here could guide the future development of novel ILs, specific for nucleic acid solutes. PMID:23181803

Chandran, Aneesh; Ghoshdastidar, Debostuti; Senapati, Sanjib

2012-12-10

385

Effects of ionic liquid on the separation of 2-chlorophenol and 2,4,6-trichlorophenol in RP-HPLC.  

PubMed

In this study, the use of ionic liquids as additives in the separation of 2-chlorophenol and 2,4,6-trichlorophenol in reversed-phase high-performance liquid chromatography is reported. The ionic liquids used were 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methylsulfate ([EMIm][MS]), and 1-octyl-3-methylimidazolium methylsulfate ([OMIm][MS]), because of their high hydrophobicity and good solvating properties. The effects of the ionic liquid on retention factor and resolution, and the change of detector response using the different ionic liquids were studied. Separation with the [MS] anion ionic liquid in the eluent resulted in better resolution than with the [BF4] anion ionic liquid. The best result was achieved using 3.0 mM/L of [OMIm][MS] and 1.0 mM/L [EMIm][MS] as mobile phase additives. PMID:19476708

Zheng, J; Row, K H

386

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

387

Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions  

NASA Astrophysics Data System (ADS)

The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods.The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods. Electronic supplementary information (ESI) available: Aggregation of PEI and PSS in [EMIm][EtSO4], detailed FTIR data, water-contact angle for (PEI/PSS)10 multilayers, and XPS survey spectra. See DOI: 10.1039/b9nr00333a

Nakashima, Takuya; Zhu, Jian; Qin, Ming; Ho, Szushen; Kotov, Nicholas A.

2010-10-01

388

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

389

Selective quenching of 2-naphtholate fluorescence by imidazolium ionic liquids.  

PubMed

The effect of addition of water-miscible ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][OTf]), and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpyrr][OTf]), on photophysical properties of 2-naphthol in water at various pHs is reported. Electronic absorbance behavior of 2-naphthol dissolved in aqueous mixtures of ILs is observed to be similar to that found in water at different pHs. The excited-state properties, however, are changed dramatically as the IL is added to the milieu. The presence of imidazolium IL results in significant quenching of the fluorescence emission from 2-naphtholate. On the contrary, pyrrolidinium IL does not quench the fluorescence from the anionic species. The quenching of 2-naphtholate fluorescence by aromatic imidazolium cations in aqueous IL mixtures is found to follow simple Stern-Volmer behavior. The aromatic imidazolium cation acts as an electron/charge acceptor during the quenching process where formation of a weakly fluorescent complex between the imidazolium cation and the excited 2-naphtholate anion possibly involving the acidic C2 proton of imidazolium is proposed. Because of the absence of such an acidic proton, the nonaromatic pyrrolidinium cation is not able to form a complex with the excited 2-naphtholate and cannot act as an electron/charge acceptor. Excited-state emission intensity decay data further corroborate this hypothesis as the intensity decay fits well to a single-exponential decay with no change in recovered lifetimes as [bmpyrr][OTf] is added; a double-exponential decay is required to satisfactorily fit the decay data in the presence of [bmim][BF(4)], hinting at the presence of a weakly fluorescent complex. The uniqueness of ILs in affecting excited-state properties of the 2-naphthol system is demonstrated through comparison with NaBF(4), NaCl, and polyethylene glycol with an average molecular weight of 200, respectively, as additives. PMID:22953779

Kumar, Vinod; Pandey, Siddharth

2012-09-24

390

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

391

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

392

Evaluation of solubility and partition properties of ampicillin-based ionic liquids.  

PubMed

In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), herein we explore a modular ionic liquid synthetic strategy for improved APIs. Ionic liquids containing l-ampicillin as active pharmaceutical ingredient anion were prepared using the methodology developed in our previous work, using organic cations selected from substituted ammonium, phosphonium, pyridinium and methylimidazolium salts, with the intent of enhancing the solubility and bioavailability of l-ampicillin forms. In order to evaluate important properties of the synthesized API-ILs, the water solubility at 25°C and 37°C (body temperature) as well as octanol-water partition coefficients (Kow's) and HDPC micelles partition at 25°C were measured. Critical micelle concentrations (CMC's) in water at 25°C and 37°C of the pharmaceutical ionic liquids bearing cations with surfactant properties were also determined from ionic conductivity measurements. PMID:23978632

Florindo, Catarina; Araújo, João M M; Alves, Filipa; Matos, Carla; Ferraz, Ricardo; Prudêncio, Cristina; Noronha, João Paulo; Petrovski, Zeljko; Branco, Luís; Rebelo, Luís Paulo N; Marrucho, Isabel M

2013-08-23

393

Formation of a liquid-crystalline interpenetrating poly-(ionic liquid) network hydrogel.  

SciTech Connect

Preparation of a liquid-crystalline ionic-liquid (IL)-based interpenetrating polymer network (IPN) is described. The IPN is prepared sequentially by first photopolymerizing a self-assembled aqueous mixture of an IL monomer (1-(10-(acryloyloxy)decyl)-3-methylimidazolium chloride) that possesses an acryloyl moiety at the terminus of a C{sub 10} alkyl chain of the IL cation. In the second step, an acrylate counteranion is introduced and then photopolymerized to yield a durable self-supporting network polymer. Thermal analysis indicates the formation of a homogeneous (well-blended constituent polymers) IPN. The IPN adopts a lamellar structure possessing some residual in-plane tetragonal perforations, as evidenced by small-angle X-ray scattering (SAXS). The IPN can absorb large quantities of water, swelling to nearly 60 times its original volume, but retains mechanical integrity making it a durable hydrogel.

Becht, G. A.; Sofos, M.; Seifert, S.; Firestone, M. A. (Materials Science Division); ( XSD)

2011-02-21

394

Molecular dynamics simulations of CO2 at an ionic liquid interface: adsorption, ordering, and interfacial crossing.  

PubMed

The ionic liquid-CO(2) system is of interest because ionic liquids have potential to be used for CO(2) capture. Using classical molecular dynamics simulations, the vacuum-liquid and CO(2) gas-liquid interfaces of the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf(2)N]) have been studied at a range of temperatures and pressures. Interfacial ordering and orientational tendencies of the ionic liquid at the vacuum interface generally agree with previous experimental and simulation studies. The interfacial structure of the IL remains relatively unperturbed when the liquid is in contact with CO(2). CO(2) adsorbs rapidly onto the liquid interface, forming a dense layer. Diffusion into the bulk occurs on a much slower time scale. Interfacial fluxes and diffusivities were determined. The potential of mean force for interfacial crossing and corresponding residence time distributions of interfacial crossing events of CO(2) were also calculated. CO(2) desorption from the liquid was also simulated. A high density CO(2) layer forms for desorption with CO(2) present but not for desorption into a vacuum. The interfacial behavior and transport dynamics have been characterized by studying these properties. PMID:20687572

Perez-Blanco, Marcos E; Maginn, Edward J

2010-09-16

395

Parallel microwave-assisted synthesis of ionic liquids and screening for denitrogenation of straight-run diesel feed by liquid-liquid extraction.  

PubMed

Fifty-six ionic liquids were efficiently synthesized in parallel format under one-pot, solvent-free microwave-assisted synthesis. These compounds were evaluated as extracting agents of nitrogen-containing compounds from a real Diesel feed before being submitted to the hydrodesulfurization process to obtain ultralow sulfur Diesel. Our results showed that halogenated ionic liquids are an excellent alternative due to these ionic liquids are relatively inexpensive, presenting a high selectivity for the extraction of nitrogen-containing compounds and can be regenerated and recycled. PMID:22263864

Ceron, Miguel A; Guzman-Lucero, Diego J; Palomeque, Jorge F; Martínez-Palou, Rafael

2012-06-01

396

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

397

The use of ionic liquids based on choline chloride for metal deposition: A green alternative?  

PubMed

Ionic liquids are studied intensively for different applications. They tend to be denoted as "green solvents", largely because of their low vapour pressure. In recent years toxicity and biotoxicity of ionic liquids have also been investigated, which proved that not all of these are "green". In this paper the use of ionic liquids based on choline chloride and ethylene glycol in electrochemistry is discussed in the context of their use as green solvents. Due to their low toxicity and ready biodegradability, these deep eutectic solvents are promising for the electrodeposition of metals. The influence of the use of these liquids as metal deposition baths on the waste water is investigated. Drag-out was found to be the most influencing parameter on the environmental impact of the process, as it is three times higher compared to classical solutions due to the higher viscosity of the ionic liquid. There are no major changes needed in the rinsing configuration of classic electroplating plants, and ion exchange to remove the metal out of the waste water was not hindered by the presence of the ionic liquid. The formation of by-products during the deposition of metals has to be further investigated and evaluated in consideration of the environmental impact. PMID:19523749

Haerens, Kurt; Matthijs, Edward; Chmielarz, Andrzej; Van der Bruggen, Bart

2009-06-11

398

Ring Opened Heterocycles: Promising Ionic Liquids for Gas Separation and Capture  

SciTech Connect

We report on a new class of highly fluid ionic liquids integrating a cation that resembles an opened imidazolium structure with two distinct anions, bis(trifluoromethylsulfonyl)imide, [Tf{sub 2}N], and a nitrile-containing anion, [C(CN)3]. These new ionic liquids show exceptional CO{sub 2} permeability values in liquid membrane gas separations with results that equal or exceed the Robeson upper bound. Moreover, these ionic liquids offer ideal CO{sub 2}/N{sub 2} selectivities competitive with the best results reported to date, exhibiting values that range from 28 to 45. The nitrile containing ionic liquid displayed the highest ideal CO{sub 2}/N{sub 2} selectivity with a value of 45 which primarily results from a reduction in the nitrogen permeability. In addition to permeability results, CO{sub 2} solubilities were also measured for the this new class of ionic liquids with values similar to the popular 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The CO{sub 2} solubility results were compared to predicted values obtained using both a modified regular solution theory and the quantum chemical Conductor-like Screening Model for Real Solvents (COSMO-RS) method. Agreement between predicted and measured solubility values is also discussed.

Mahurin, Shannon Mark [ORNL; Yeary, Joshua S [ORNL; Baker, Sheila N [ORNL; Jiang, Deen [ORNL; Dai, Sheng [ORNL; Baker, Gary A [ORNL

2012-01-01

399

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

400

The study of factors affecting the enzymatic hydrolysis of cellulose after ionic liquid pretreatment  

Microsoft Academic Search

Cellulose resource has got much attention as a promising replacement of fossil fuel. The hydrolysis of cellulose is the key step to chemical product and liquid transportation fuel. In this paper a serials of chloride, acetate, and formate based ionic liquids were used as solvents to dissolve cellulose. The cellulose regenerated from ILs was characterized by FTIR and X-ray powder

Wenwen Xiao; Wang Yin; Shuqian Xia; Peisheng Ma

401

NOVEL IONIC LIQUID THERMAL STORAGE FOR SOLAR THERMAL ELECTRIC POWER SYSTEMS  

Microsoft Academic Search

Feasibility of ionic liquids as liquid thermal storage media and heat transfer fluids in a solar thermal power plant was investigated. Many ionic liquids such as (C4min)(PF6), (C8mim)(PF6), (C4min)(bistrifluromethane sulflonimide), (C4min)(BF4), (C 8mim)(BF4), and (C4min)( bistrifluromethane sulflonimide) were synthesized and characterized using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), nuclear magnetic resonance (NMR), viscometry, and some other methods. Properties such

Banqiu Wu; Ramana G. Reddy; Robin D. Rogers

402

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

403

Cyano-containing quaternary ammonium-based ionic liquid as a ‘co-solvent’ for lithium battery electrolyte  

Microsoft Academic Search

Imidazolium-based ionic liquid is one of attractive candidates for advanced lithium battery electrolyte. However, its cathodic stability is not sufficient for the reversible charge–discharge of negative electrodes. The authors previously proposed a quaternary ammonium-based ionic liquid containing a cyano group (cyano-QA) as a film-forming electrolyte on the negative electrode surface. In the present study, several cyano-QA ionic liquids have been

Minato Egashira; Maika Nakagawa; Izumi Watanabe; Shigeto Okada; Jun-ichi Yamaki

2005-01-01

404

Combining ionic liquids and polyethylene glycols to boost the hydrophobic-hydrophilic range of aqueous biphasic systems.  

PubMed

This work reveals, for the first time, that polymer-ionic-liquid-based aqueous biphasic systems (ABS) exhibit a much wider hydrophilic-hydrophobic range than conventional systems reported to date. Three probe dyes were used to demonstrate that either the polymer-rich or the ionic-liquid-rich layer can serve as the most hydrophobic phase. It was found that the phase polarities can be easily tuned by the choice of an appropriate ionic liquid. PMID:24145792

Pereira, Jorge F B; Rebelo, Luís Paulo N; Rogers, Robin D; Coutinho, João A P; Freire, Mara G

2013-10-22

405

Correlation of the Melting Points of Potential Ionic Liquids (Imidazolium Bromides and Benzimidazolium Bromides) Using the CODESSA Program  

Microsoft Academic Search

The melting points of several imidazolium-based ionic liquids or ionic liquid analogues were correlated using the CODESSA program in order to develop predictive tools for determination of suitable ionic liquid salts. The data set consisted of melting point data ( °C) for 104 substituted imidazolium bromides divided on the basis of the N-substituents into three subsets: A-57 compounds, B-29 compounds,

Alan R. Katritzky; Ritu Jain; Andre Lomaka; Ruslan Petrukhin; Mati Karelson; Ann E. Visser; Robin D. Rogers

2002-01-01

406

Thermodynamic studies of partitioning behavior of cytochrome c in ionic liquid-based aqueous two-phase system  

Microsoft Academic Search

The ionic liquid\\/aqueous two-phase extraction systems (ATPSs) based on imidazolium ionic liquids were used to extract cytochrome c. Effects of the alkyl chain length of the ionic liquid cations, concentration of potassium citrate, temperature and pH on the extraction efficiency have been investigated. The thermodynamic parameters (?GT°, ?HT° and ?ST°) associated with Cyt-c partitioning in aqueous two phase systems were

Yanmin Lu; Wenjuan Lu; Wei Wang; Qingwei Guo; Yanzhao Yang

407

Friction and wear behaviors of ionic liquid of alkylimidazolium hexafluorophosphates as lubricants for steel\\/steel contact  

Microsoft Academic Search

Ionic liquids of the alkylimidazolium hexafluorophosphate type were prepared and evaluated as lubricants for the contact of steel\\/steel. Their tribological properties of the synthetic ionic liquid as the lubricants were investigated on an Optimol SRV oscillating friction and wear tester in ambient condition and on a CZM vacuum friction tester at 1×10?3Pa. These synthetic ionic liquids show excellent tribological performance

Haizhong Wang; Qiming Lu; Chengfeng Ye; Weimin Liu; Zhaojie Cui

2004-01-01

408

Partition Coefficients of Alkaloids in Biphasic Ionic-Liquid-Aqueous Systems and their Dependence on the Hofmeister Series  

Microsoft Academic Search

The aim of this work is to test the potential of hydrophobic phosphonium-based ionic liquids for the extraction of caffeine and nicotine from aqueous phases through the determination of the alkaloids' partition coefficients. It was found that the caffeine partitioning for the ionic-liquid-rich phase increases with the ionic liquid hydrogen-bonding accepting capability (or water content), while for nicotine a nearly

Mara G. Freire; Ana Rita R. Teles; José N. Canongia Lopes; Luís Paulo N. Rebelo; Isabel M. Marrucho; João A. P. Coutinho

2012-01-01

409

Carbon dioxide capture by a dual amino ionic liquid with amino-functionalized imidazolium cation and taurine anion  

Microsoft Academic Search

A dual amino ionic liquid with amino-functionalized imidazolium cation and taurine anion was synthesized and characterized. Absorption isotherm of carbon dioxide into the ionic liquid was investigated using a volumetric method at 303.15 and 323.15K. Results showed that absorption capacity reached about 0.9mol carbon dioxide per mol of ionic liquid at ambient pressure, which is a chemical process verified by

Zhimin Xue; Zhaofu Zhang; Jin Han; Yu Chen; Tiancheng Mu

2011-01-01

410

Ionic liquids for simultaneous preconcentration of some lanthanoids using dispersive liquid-liquid microextraction technique in uranium dioxide powder.  

PubMed

Ionic liquids in a dispersive liquid-liquid microextraction technique were used for determination of lanthanoids such as samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. In this process, an appropriate mixture of extraction solvent and disperser is rapidly injected into an aqueous sample containing samarium, europium, gadolinium, and dysprosium ions complexes with 1-hydroxy-2, 5-pyrrolidinedione, and consequently a cloudy solution is formed. It consists of fine droplets of extraction solventwhich are dispersed entirely into the aqueous phase. After centrifugation of this solution, the whole enriched phase was determined by inductively coupled plasma optical emission spectrometry. In the present work, the preconcentration factor, limit of detection, and relative standard deviation were investigated for samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. PMID:19368197

Mallah, Mohammad H; Shemirani, Farzaneh; Maragheh, Mohammad G

2009-03-15

411

Determination of rutin and quercetin in Chinese herbal medicine by ionic liquid-based pressurized liquid extraction–liquid chromatography–chemiluminescence detection  

Microsoft Academic Search

A novel ionic liquid-based pressurized liquid extraction (IL-PLE) procedure coupled with high performance liquid chromatography (HPLC) tandem chemiluminescence (CL) detection capable of quantifying trace amounts of rutin and quercetin in four Chinese medicine plants including Flos sophorae Immaturus, Crateagus pinnatifida Bunge, Hypericum japonicum Thunb and Folium Mori was described in this paper. To avoid environmental pollution and toxicity to the

Hongwei Wu; Meilan Chen; Yunchang Fan; Fawzi Elsebaei; Yan Zhu

412

Inclusion complex formation of ionic liquids with cucurbit[7]uril studied by competitive binding of methylene blue fluorescent probe.  

PubMed

Methylene blue (MB) was used as a fluorescent probe to study the encapsulation of three kinds of 1-butyl-3-methylimidazolium ionic liquids in cucurbit[7]uril (CB7) at pH 3. Addition of ionic liquids to the aqueous solution of MB-CB7 inclusion complexes brought about considerable fluorescence intensity quenching, and it was because that MB was extruded from the cavity of CB7 into the aqueous phase by the ionic liquid. NMR and AM1 semi-empirical calculations indicated that the 1-butyl-imidazolium moiety of ionic liquid was responsible for the complexation with CB7. PMID:22683553

Cui, Shuya; Du, Junliang; Wang, Tao; Hu, Xiaoli

2012-05-22

413

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

414

Polymerizable ionic liquids for fixed junction light-emitting electrochemical cells  

NASA Astrophysics Data System (ADS)

Fixed junction light-emitting electrochemical cells (LECs) have been shown to offer several advantages over traditional dynamic junction LECs. Recently we have reported fixed junction LECs that use ion-pair monomers (IPMs) in order to eliminate counterionic mobility. However, the materials presented in our previous work had poor miscibility of IPMs with electroluminescent polymers and poor ion dissociation/mobility. Here we report on the synthesis and performance of polymerizable ionic liquids (PILs) as candidates for ionic charge carriers in LEC device structures. PILs are advantageous since they combine the improved materials properties of ionic liquids with the fixed-junction functionality of IPMs. Devices employing PILs had uniform film morphology and showed diode-like behavior. In addition, brightness was improved by an order of magnitude compared to IPM based devices reported earlier. The materials developed here, besides having advantages in LECs, may also find utility in additional applications in which control over ionic mobility or electrochemical doping is crucial.

Kosilkin, Ilya; Martens, Matt; Murphy, Michael; Leger, Janelle

2010-03-01

415

Recombination of Photogenerated Lophyl Radicals in Imidazolium-Based Ionic Liquids  

SciTech Connect

Laser flash photolysis is applied to study the recombination reaction of lophyl radicals in ionic liquids in comparison with dimethylsulfoxide as an example of a traditional organic solvent. The latter exhibits a similar micropolarity as the ionic liquids. The ionic liquids investigated are 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1), 1-hexyl-3-methylimidazolium hexafluorophosphate (2), and 1-butyl-3-methylimidazolium tetafluoroborate (3). The recombination of the photolytic generated lophyl radicals occur significantly faster in the ionic liquids than expected from their macroscopic viscosities and is a specific effect of these ionic liquids. On the other hand, this reaction can be compared with the macroscopic viscosity in the case of dimethylsulfoxide. Activation parameters obtained for lophyl radical recombination suggest different, anion-dependent mechanistic effects. Quantum chemical calculations based on density functional theory provide a deeper insight of the molecular properties of the lophyl radical and its precursor. Thus, excitation energies, spin densities, molar volumes, and partial charges are calculated. Calculations show a spread of spin density over the three carbon atoms of the imidazolyl moiety, while only low spin density is calculated for the nitrogens.

Strehmel, V.; Wishart, J.; Polyansky, D.E.; Strehmel, B.

2009-10-20

416

Studies of ionic liquids in lithium-ion battery test systems  

SciTech Connect

In this work, thermal and electrochemical properties of neat and mixed ionic liquid - lithium salt systems have been studied. The presence of a lithium salt causes both thermal and phase-behavior changes. Differential scanning calorimeter DSC and thermal gravimetric analysis TGA were used for thermal analysis for several imidazolium bis(trifluoromethylsulfonyl)imide, trifluoromethansulfonate, BF{sub 4}, and PF{sub 6} systems. Conductivities and diffusion coefficient have been measured for some selected systems. Chemical reactions in electrode - ionic liquid electrolyte interfaces were studied by interfacial impedance measurements. Lithium-lithium and lithium-carbon cells were studied at open circuit and a charged system. The ionic liquids studied include various imidazolium systems that are already known to be electrochemically unstable in the presence of lithium metal. In this work the development of interfacial resistance is shown in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell as well as results from some cycling experiments. As the ionic liquid reacts with the lithium electrode the interfacial resistance increases. The results show the magnitude of reactivity due to reduction of the ionic liquid electrolyte that eventually has a detrimental effect on battery performance.

Salminen, Justin; Prausnitz, John M.; Newman, John

2006-06-01

417

Global transcriptome response to ionic liquid by a tropical rain forest soil bacterium, Enterobacter lignolyticus.  

PubMed

To process plant-based renewable biofuels, pretreatment of plant feedstock with ionic liquids has significant advantages over current methods for deconstruction of lignocellulosic feedstocks. However, ionic liquids are often toxic to the microorganisms used subsequently for biomass saccharification and fermentation. We previously isolated Enterobacter lignolyticus strain SCF1, a lignocellulolytic bacterium from tropical rain forest soil, and report here that it can grow in the presence of 0.5 M 1-ethyl-3-methylimidazolium chloride, a commonly used ionic liquid. We investigated molecular mechanisms of SCF1 ionic liquid tolerance using a combination of phenotypic growth assays, phospholipid fatty acid analysis, and RNA sequencing technologies. Potential modes of resistance to 1-ethyl-3-methylimidazolium chloride include an increase in cyclopropane fatty acids in the cell membrane, scavenging of compatible solutes, up-regulation of osmoprotectant transporters and drug efflux pumps, and down-regulation of membrane porins. These findings represent an important first step in understanding mechanisms of ionic liquid resistance in bacteria and provide a basis for engineering microbial tolerance. PMID:22586090

Khudyakov, Jane I; D'haeseleer, Patrik; Borglin, Sharon E; Deangelis, Kristen M; Woo, Hannah; Lindquist, Erika A; Hazen, Terry C; Simmons, Blake A; Thelen, Michael P

2012-05-14

418

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

419

Halogen-free ionic liquids and their utilization as cellulose solvents  

NASA Astrophysics Data System (ADS)

This work demonstrates a novel synthesis route to halogen-free ionic liquids. A one-pot synthetic reaction route avoiding the use of toxic and high-energetic alkyl halides was developed to reduce the environmental impact of the synthesis process of ionic liquids. However, the elimination of halogens and alkyl halides in the preparation of ionic liquids is not just an environmental issue: the aforementioned species are also among the most common and persistent contaminants in today's Ionic Liquids (ILs). Thus, this paper introduces a range of quaternized nitrogen based ionic liquids, including both aromatic and non-aromatic components, all prepared without alkyl halides in any step of the process. Moreover, bio-renewable precursors such as (bio-)alcohols and carboxylic acids were employed as anion sources and alkylation media, thus avoiding halogen contamination or halogen-containing anions. The IL's prepared were designed to dissolve cellulose, some of which was included in a cellulose dissolution study using a sulphite cellulose from the company Domsjö.

Gräsvik, John; Eliasson, Bertil; Mikkola, Jyri-Pekka

2012-11-01

420

Ionic Liquids as Novel Lubricants and Additives for Diesel Engine Applications  

SciTech Connect

The lubricating properties of two ionic liquids with the same anion but different cations, one ammonium IL [C8H17]3NH.Tf2N and one imidazolium IL C10mim.Tf2N, were evaluated both in neat form and as oil additives. Experiments were conducted using a standardized reciprocating sliding test using a segment of a Cr-plated diesel engine piston ring against a grey cast iron flat specimen with simulated honing marks as on the engine cylinder liner. The selected ionic liquids were benchmarked against conventional hydrocarbon oils. Substantial friction and wear reductions, up to 55% and 34%, respectively, were achieved for the neat ionic liquids compared to a fully-formulated 15W40 engine oil. Adding 5 vol% ILs into mineral oil has demonstrated significant improvement in the lubricity. One blend even outperformed the 15W40 engine oil with 9% lower friction and 34% less wear. Lubrication regime modeling, worn surface morphology examination, and surface chemical analysis were conducted to help understand the lubricating mechanisms for ionic liquids. Results suggest great potential for using ionic liquids as base lubricants or lubricant additives for diesel engine applications.

Qu, Jun [ORNL; Blau, Peter Julian [ORNL; Dai, Sheng [ORNL; Luo, Huimin [ORNL; Meyer III, Harry M [ORNL

2009-01-01

421

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

422

Photochromism of nitrobenzospiropyran in phosphonium based ionic liquids.  

PubMed

The photo-, thermo- and solvatochromic properties of 2,3-dihydro-1',3',3'-trimethyl-6-nitrospiro[1-benzopyran-2,2'-1H-indole] (BSP) and its photo-induced merocyanine isomer (MC) were investigated in phosphonium based ILs by UV-vis absorption spectroscopy. It was found that the kinetics and thermodynamics of the BSP <--> MC equilibrium were sensitive to the nature of the anion. The MC lambda(max) shifted from 560 nm to 578 nm when in solutions of [P(1,4,4,4)][tos] and [P(6,6,6,14)][dca], respectively. The BSP isomer was highly favoured at equilibrium in the ILs studied; K(e) values observed were similar to non-polar solvents such as dichloromethane. The thermal relaxation of MC in all ILs is first order, and in comparison with aprotic polar solvents possessing comparable polarity (such as acetonitrile). Thermal relaxation rates of MC were monitored over a range of temperatures; at 293 K rates varied from 5.19 to 25.03 x 10(-4) s(-1). A non-linear relationship between K(e) and k was observed; this contradicts what is expected for BSP in molecular solvents and suggests the isomers exhibit different molecular/solvation environments. The energetics of the thermal relaxation of MC in ILs were observed; activation energies ranged from 71 to 90 kJ mol(-1) and all ILs exhibit negative activation entropies ranging between -72 and -8.2 J K(-1) mol(-1). A linear relationship between activation energy and entropy was observed. PMID:19672540

Byrne, Robert; Coleman, Simon; Fraser, Kevin J; Raduta, Ana; MacFarlane, Douglas R; Diamond, Dermot

2009-06-09

423

Biosensor for chlorogenic acid based on an ionic liquid containing iridium nanoparticles and polyphenol oxidase  

Microsoft Academic Search

A biosensor based on the ionic liquid, 1-n-butyl-3-methylimidazolium hexafluorophosphate containing dispersed iridium nanoparticles (Ir-BMI.PF6) and polyphenol oxidase was constructed. This enzyme was obtained from the sugar apple (Annona squamosa), immobilized in chitosan ionically crosslinked with oxalate. The biosensor was used for determination of chlorogenic acid by square wave voltammetry. The polyphenol oxidase catalyzes the oxidation of chlorogenic acid to the

Suellen C. Fernandes; Sally K. Moccelini; Carla W. Scheeren; Pedro Migowski; Jairton Dupont; Melina Heller; Gustavo A. Micke; Iolanda C. Vieira

2009-01-01

424

Aggregation behavior of a chiral long-chain ionic liquid in aqueous solution  

Microsoft Academic Search

The synthesis of a chiral long-chain ionic liquid (IL), S-3-hexadecyl-1-(1-hydroxy-propan-2-yl)-imidazolium bromide ([C16hpim]Br), is presented. The adsorption and aggregation of this surface active IL in aqueous solution is described. The critical micelle concentration (cmc) measurement suggests that the chiral IL has superior capacity for micelle formation compared to traditional ionic surfactants. The relatively larger hydrophilic head group of the IL results

Xin-Wei Li; Yan-An Gao; Jie Liu; Li-Qiang Zheng; Bin Chen; Li-Zhu Wu; Chen-Ho Tung

2010-01-01

425

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-liqui