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1

Aprotic ionic liquids as electrolyte components in protonic membranes  

Microsoft Academic Search

In this paper we describe the preparation and the properties of a series of aprotic ionic liquid-based, proton-conducting\\u000a membranes. The ionic liquids (ILs) 1,2-dimethyl-3-n-propylimidazolium bis(trifluoromethanesulfonyl)imide and the 3-methyl-1-n-propylpyridinium bis(trifluoromethanesulfonyl)imide are used as the casting solvents of PVdF gel-type membranes; the proton\\u000a conductivity is achieved by the addition of a superacid component, namely, trifluoromethanesulfonic acid (HTf) or N,N-bis(trifluoromethanesulfonyl)imide\\u000a (HTFSI). The polymer

Alessandra Fernicola; Maria Assunta Navarra; Stefania Panero

2008-01-01

2

Interactions in ion pairs of protic ionic liquids: Comparison with aprotic ionic liquids  

SciTech Connect

The stabilization energies for the formation (E{sub form}) of 11 ion pairs of protic and aprotic ionic liquids were studied by MP2/6-311G{sup **} level ab initio calculations to elucidate the difference between the interactions of ions in protic ionic liquids and those in aprotic ionic liquids. The interactions in the ion pairs of protic ionic liquids (diethylmethylammonium [dema] and dimethylpropylammonium [dmpa] based ionic liquids) are stronger than those of aprotic ionic liquids (ethyltrimethylammonium [etma] based ionic liquids). The E{sub form} for the [dema][CF{sub 3}SO{sub 3}] and [dmpa][CF{sub 3}SO{sub 3}] complexes (?95.6 and ?96.4 kcal/mol, respectively) are significantly larger (more negative) than that for the [etma][CF{sub 3}SO{sub 3}] complex (?81.0 kcal/mol). The same trend was observed for the calculations of ion pairs of the three cations with the Cl{sup ?}, BF{sub 4}{sup ?}, TFSA{sup ?} anions. The anion has contact with the N–H bond of the dema{sup +} or dmpa{sup +} cations in the most stable geometries of the dema{sup +} and dmpa{sup +} complexes. The optimized geometries, in which the anions locate on the counter side of the cations, are 11.0–18.0 kcal/mol less stable, which shows that the interactions in the ions pairs of protic ionic liquids have strong directionality. The E{sub form} for the less stable geometries for the dema{sup +} and dmpa{sup +} complexes are close to those for the most stable etma{sup +} complexes. The electrostatic interaction, which is the major source of the attraction in the ion pairs, is responsible for the directionality of the interactions and determining the magnitude of the interaction energy. Molecular dynamic simulations of the [dema][TFSA] and [dmpa][TFSA] ionic liquids show that the N–H bonds of the cations have contact with the negatively charged (oxygen and nitrogen) atoms of TFSA{sup ?} anion, while the strong directionality of the interactions was not suggested from the simulation of the [etma][CF{sub 3}SO{sub 3}] ionic liquid.

Tsuzuki, Seiji, E-mail: s.tsuzuki@aist.go.jp [Research Initiative of Computational Sciences (RICS), Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)] [Research Initiative of Computational Sciences (RICS), Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Shinoda, Wataru [Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)] [Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Miran, Md. Shah; Kinoshita, Hiroshi; Yasuda, Tomohiro; Watanabe, Masayoshi [Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)] [Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

2013-11-07

3

A comparative study of the terrestrial ecotoxicity of selected protic and aprotic ionic liquids.  

PubMed

Ionic liquids (ILs) are a fairly new and very promising group of compounds with a vast variety of possible structures and uses. They are considered to be potentially "green", but their impact on the environment tends to be neglected or not studied enough, especially when it comes to terrestrial ecotoxicity, where there are very few studies performed to date. This work presents a comparative study of the terrestrial ecotoxicity of selected representatives of two ILs groups: a new family of protic ILs (derived from aliphatic amines and organic acids) and some frequently used aprotic ILs (substituted imidazolium and piridinium chlorides). Toxicity of the ILs towards three terrestrial plant species (Allium cepa, Lolium perenne and Raphanus sativus) and soil microorganisms involved in carbon and nitrogen transformation was analyzed. Protic ILs have shown no toxic effect in most of the tests performed. The EC50 values for aprotic ILs are various orders of magnitude lower than the ones for protic ILs in all of the tests. The most toxic ILs are the most complex ones in both of the analyzed groups. Protic ILs seem to have a potential for biodegradation in soil, while aprotic ILs exhibit inhibitory effects towards the carbon transforming microbiota. These findings indicate that protic ILs can be considered as less toxic and safer for the terrestrial environment than the aprotic ILs. PMID:24630250

Peric, Brezana; Sierra, Jordi; Martí, Esther; Cruañas, Robert; Garau, Maria Antonia

2014-08-01

4

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

5

Aprotic Heterocyclic Anion Triazolide Ionic Liquids - A New Class of Ionic Liquid Anion Accessed by the Huisgen Cycloaddition Reaction  

SciTech Connect

The triazole core is a highly versatile heterocyclic ring which can be accessed easily with the Cu(I)-catalyzed Huisgen cycloaddition reaction. Herein we present the preparation of ionic liquids that incorporate a 1,2,3-triazolide anion. These ionic liquids were prepared by a facile procedure utilizing a base-labile pivaloylmethyl group at the 1-position, which can act as precursors to 1H- 4-substituted 1,2,3-triazole. These triazoles were then subsequently converted into ionic liquids after deprotonation using an appropriate ionic liquid cation hydroxide. The densities and thermal decompositions of these ionic liquids were measured. These novel ionic liquids have potential applications in gas separations and in metal-free catalysis.

Thompson, Robert L.; Damodaran, Krishnan; Luebke, David; Nulwala, Hunaid

2013-06-01

6

Chemically Tunable Ionic Liquids with Aprotic Heterocyclic Anion (AHA) for CO2 Capture.  

PubMed

Ionic liquids (ILs) with aprotic heterocyclic anions, or AHAs, can bind CO2 with reaction enthalpies that are suitable for gas separations and without suffering large viscosity increases. In the present work, we have synthesized ILs bearing an alkyl-phosphonium cation with indazolide, imidazolide, pyrrolide, pyrazolide and triazolide-based anions that span a wide range of predicted reaction enthalpies with CO2. Each AHA-based IL was characterized by NMR spectroscopy and their physical properties (viscosity, glass transition, and thermal decomposition temperature) determined. In addition, the influence of substituent groups on the reaction enthalpy was investigated by measuring the CO2 solubility in each IL at pressures between 0 and 1 bar at 22 °C using a volumetric method. The isotherm-derived enthalpies range between -37 and -54 kJ mol(-1) of CO2, and these values are in good agreement with computed enthalpies of gas-phase IL-CO2 reaction products from molecular electronic structure calculations. The AHA ILs show no substantial increase in viscosity when fully saturated with CO2 at 1 bar. Phase splitting and compositional analysis of one of the IL/H2O and IL/H2O/CO2 systems conclude that protonation of the 2-cyanopyrrolide anion is improbable, and this result was confirmed by the equimolar CO2 absorption in the presence of water. Taking advantage of the tunable binding energy and absence of viscosity increase after the reaction with CO2, AHA ILs are promising candidates for efficient and environmental-friendly absorbents in postcombustion CO2 capture. PMID:24811264

Seo, Samuel; Quiroz-Guzman, Mauricio; DeSilva, M Aruni; Lee, Tae Bum; Huang, Yong; Goodrich, Brett F; Schneider, William F; Brennecke, Joan F

2014-05-29

7

Studies on thermal properties of selected aprotic and protic ionic liquids  

SciTech Connect

We describe herein the thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) investigations of the thermal properties of selected room-temperature ionic liquids (RTILs). The dependence of the thermal properties on both cation and anion structures of RTILs was systematically studied. The ionic liquids (ILs) investigated here include 28 different imidazolium-based ILs, 22 ammonium-based ILs, and 16 amide-based ILs. In general, these three cation classes exhibit different thermal behaviors but follow a quite systematic trend as expected from the corresponding structural variation. The ILs with bromide as the conjugate anion have lower thermal stabilities than those with bis(trifluoromethane sulfonyl) imide or bis(perfluoroethyl sulfonyl) imide as the conjugate anion. The mass of TGA samples and scan rate were found to have a systematic effect on the decomposition temperature of ILs, highlighting the caution needed in reporting TGA results.

Luo, Huimin [ORNL; Dai, Sheng [ORNL; Huang, Jing-Fang [ORNL

2008-01-01

8

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

9

Effect of water on the transport properties of protic and aprotic imidazolium ionic liquids - an analysis of self-diffusivity, conductivity, and proton exchange mechanism.  

PubMed

In this paper we report on the transport properties of protic and aprotic ionic liquids of the imidazolium cation (C2C1Im(+) or C2HIm(+)) and the TFSI(-) or TfO(-) anion as a function of added water. We observe that the self-diffusion coefficient of the ionic species increases upon addition of water, and that the cation diffuses faster than the anion in the entire water concentration range investigated. We also observe that the overall increase of anionic and cationic diffusion coefficients is significant for C2HImTfO while it is rather weak for C2C1ImTFSI, the former being more hydrophilic. Moreover, the difference between cationic and anionic self-diffusivity specifically depends on the structure of the ionic liquid's ions. The degree of ion-ion association has been investigated by comparing the molar conductivity obtained by impedance measurements with the molar conductivity calculated from NMR data using the Nernst-Einstein equation. Our data indicate that the ions are partly dissociated (?imp/?NMR in the range 0.45-0.75) but also that the degree of association decreases in the order C2HImTfO > C2HImTFSI ? C2C1ImTfO > C2C1ImTFSI. From these results, it seems that water finds different sites of interaction in the protic and aprotic ionic liquids, with a strong preference for hydrogen bonding to the -NH group (when available) and a stronger affinity to the TfO anion as compared to the TFSI. For the protic ionic liquids, the analysis of (1)H NMR chemical shifts (upon addition of H2O and D2O, respectively) indicates a water-cation interaction of hydrogen bonding nature. In addition, we could probe proton exchange between the -NH group and deuterated water for the protic cation, which occurs at a significantly faster rate if associated with the TfO anion as compared to the TFSI. PMID:24714867

Yaghini, N; Nordstierna, L; Martinelli, A

2014-04-23

10

Ionic Liquids Database- (ILThermo)  

National Institute of Standards and Technology Data Gateway

SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

11

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

12

The distillation and volatility of ionic liquids  

NASA Astrophysics Data System (ADS)

It is widely believed that a defining characteristic of ionic liquids (or low-temperature molten salts) is that they exert no measurable vapour pressure, and hence cannot be distilled. Here we demonstrate that this is unfounded, and that many ionic liquids can be distilled at low pressure without decomposition. Ionic liquids represent matter solely composed of ions, and so are perceived as non-volatile substances. During the last decade, interest in the field of ionic liquids has burgeoned, producing a wealth of intellectual and technological challenges and opportunities for the production of new chemical and extractive processes, fuel cells and batteries, and new composite materials. Much of this potential is underpinned by their presumed involatility. This characteristic, however, can severely restrict the attainability of high purity levels for ionic liquids (when they contain poorly volatile components) in recycling schemes, as well as excluding their use in gas-phase processes. We anticipate that our demonstration that some selected families of commonly used aprotic ionic liquids can be distilled at 200-300°C and low pressure, with concomitant recovery of significant amounts of pure substance, will permit these currently excluded applications to be realized.

Earle, Martyn J.; Esperança, José M. S. S.; Gilea, Manuela A.; Canongia Lopes, José N.; Rebelo, Luís P. N.; Magee, Joseph W.; Seddon, Kenneth R.; Widegren, Jason A.

2006-02-01

13

Ionic liquids in catalysis  

Microsoft Academic Search

The current state of the art of the application of ionic liquids in catalysis is reviewed. The review selects examples of the different ways in which ionic liquids have been applied in catalysis, i.e. as the catalyst itself, as a co-catalyst or catalyst activator, as the source of a new ligand for a catalytic metal centre, or just as the

Tom Welton

2004-01-01

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

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

16

Synthesis of Ionic Liquids.  

National Technical Information Service (NTIS)

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 ...

H. Luo S. Dai

2003-01-01

17

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

18

Spotlight on ionic liquids  

Microsoft Academic Search

Ionic liquids are an emerging class of materials with a diverse and extraordinary set of properties. Understanding the origins of these properties and how they can be controlled by design to serve valuable practical applications presents a wide array of challenges and opportunities to the chemical physics and physical chemistry community. We highlight here some of the significant progress already

Edward W. Castner; James F. Wishart

2010-01-01

19

Potentialities of ionic liquids as new electrolyte media in advanced electrochemical devices  

Microsoft Academic Search

This paper reviews the various classes of ionic liquids (ILs) in view of their established and expected applications in advanced electrochemical devices, such as lithium batteries, fuel cells, and supercapacitors. In this respect, particular attention is devoted to aprotic and protic ILs, with a related discussion in terms of their thermal and transport properties. In addition, the role in the

A. Fernicola; B. Scrosati; H. Ohno

2006-01-01

20

Criteria for solvate ionic liquids.  

PubMed

Certain concentrated mixtures of salts and solvents are not simply "solutions" anymore, but they may be described as "ionic liquids". In this perspective paper, we describe possible criteria for the new family of ionic liquids: "solvate" ionic liquids. This subclass of ionic liquids was originally proposed by Angell et al. in their recent review; however, their criteria remain to be debated. Concentrated mixtures of lithium salts and organic solvents are useful models for these solvate ionic liquids, and the effects of the salt concentration, types of solvents, and counter anions of the lithium salts on their structure and properties have been explored to enable contrast with traditional solutions, and to help determine whether a given mixture belongs to the solvate ionic liquid or not. PMID:24676567

Mandai, Toshihiko; Yoshida, Kazuki; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi

2014-05-21

21

Properties of ionic liquid solvents for catalysis  

Microsoft Academic Search

Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of

John S Wilkes

2004-01-01

22

Ionic liquids in confined geometries.  

PubMed

Over recent years the Surface Force Apparatus (SFA) has been used to carry out model experiments revealing structural and dynamic properties of ionic liquids confined to thin films. Understanding characteristics such as confinement induced ion layering and lubrication is of primary importance to many applications of ionic liquids, from energy devices to nanoparticle dispersion. This Perspective surveys and compares SFA results from several laboratories as well as simulations and other model experiments. A coherent picture is beginning to emerge of ionic liquids as nano-structured in pores and thin films, and possessing complex dynamic properties. The article covers structure, dynamics, and colloidal forces in confined ionic liquids; ionic liquids are revealed as a class of liquids with unique and useful confinement properties and pertinent future directions of research are highlighted. PMID:22301770

Perkin, Susan

2012-04-21

23

Specialist gelator for ionic liquids.  

PubMed

Cyclo(l-beta-3,7-dimethyloctylasparaginyl-L-phenylalanyl) (1) and cyclo(L-beta-2-ethylhexylasparaginyl-L-phenylalanyl) (2), prepared from L-asparaginyl-L-phenylalanine methyl ester, have been found to be specialist gelators for ionic liquids. They can gel a wide variety of ionic liquids, including imizazolium, pyridinium, pyrazolidinium, piperidinium, morpholinium, and ammonium salts. The mean minimum gel concentrations (MGCs) necessary to make gels at 25 degrees C were determined for ionic liquids. The gel strength increased at a rate nearly proportional to the concentration of added gelator. The strength of the transparent gel of 1-butylpyridinium tetrafluoroborate ([C(4)py]BF(4)), prepared at a concentration of 60 g L(-1) (gelator 1/[C(4)py]BF(4)), was ca. 1500 g cm(-2). FT-IR spectroscopy indicated that a driving force for gelation was intermolecular hydrogen bonding between amides and that the phase transition from gel to liquid upon heating was brought about by the collapse of hydrogen bonding. The gels formed from ionic liquids were very thermally stable; no melting occurs up to 140 degrees C when the gels were prepared at a concentration of 70 g L(-1) (gelator/ionic liquid). The ionic conductivities of the gels were nearly the same as those of pure ionic liquids. The gelator had electrochemical stability and a wide electrochemical window. When the gels were prepared from ionic liquids containing propylene carbonate, the ionic conductivities of the resulting gels increased to levels rather higher than those of pure ionic liquids. The gelators also gelled ionic liquids containing supporting electrolytes. PMID:16262296

Hanabusa, Kenji; Fukui, Hiroaki; Suzuki, Masahiro; Shirai, Hirofusa

2005-11-01

24

Ionic liquids in electrochromic devices  

Microsoft Academic Search

The ionic liquid (PYR14TFSI) has proved to be the key material to make a Li-ion conducting element of a complete electrochromic device, when interposed between transparent film electrodes like WO3 and Li-charged V2O5. The key features of this ionic liquid and its mixtures with LiTFSI are the excellent transparency in the visible and NIR optical regions, the good ionic conductivity

A. Brazier; G. B. Appetecchi; S. Passerini; A. Surca Vuk; B. Orel; F. Donsanti; F. Decker

2007-01-01

25

Particle self-assembly at ionic liquid-based interfaces.  

PubMed

This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid-water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid-water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water-ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil or water is incorporated. PMID:24230971

Frost, Denzil S; Nofen, Elizabeth M; Dai, Lenore L

2014-04-01

26

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

27

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

28

Anion pairs in room temperature ionic liquids predicted by molecular dynamics simulation, verified by spectroscopic characterization  

SciTech Connect

Molecular-level spectroscopic analyses of an aprotic and a protic room-temperature ionic liquid, BMIM OTf and BMIM HSO4, respectively, have been carried out with the aim of verifying molecular dynamics simulations that predict anion pair formation in these fluid structures. Fourier-transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy of various nuclei support the theoretically-determined average molecular arrangements.

Schwenzer, Birgit; Kerisit, Sebastien N.; Vijayakumar, M.

2014-01-01

29

Ionic liquids: applications in catalysis  

Microsoft Academic Search

The use of room temperature ionic liquids as either solvents or catalysts has been the subject of considerable recent attention because of the prospects for “green” catalysis. This paper presents a review of the potential applications of these unique liquid materials in industrial catalysis.

Dongbin Zhao; Min Wu; Yuan Kou; Enze Min

2002-01-01

30

Improved ionic conductivity of nitrile rubber\\/ionic liquid composites  

Microsoft Academic Search

Polymer electrolytes with high ionic conductivity and good elasticity were prepared by mixing nitrile rubber (poly(acrylonitrile-co-butadiene) rubber; NBR) with ionic liquid, N-ethylimidazolium bis(trifluoromethanesulfonyl)imide (EImTFSI). The NBR\\/EImTFSI composites were obtained as homogeneous and transparent films when the ionic liquid content was less than 60wt%. Raman spectroscopy suggested the interaction between nitrile group of NBR and TFSI anion. Sample with ionic liquid

Edy Marwanta; Tomonobu Mizumo; Nobuhumi Nakamura; Hiroyuki Ohno

2005-01-01

31

Thermophysical properties of ionic liquids.  

PubMed

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. PMID:21107798

Rooney, David; Jacquemin, Johan; Gardas, Ramesh

2010-01-01

32

Elucidation of ionic interactions in the protic ionic liquid solutions by isothermal titration calorimetry.  

PubMed

The strong hydrogen-bonded network noted in protic ionic liquids (PILs) may lead to stronger interactions of the ionic entities of PILs with solvents (water, methanol, ethylene glycol, dimethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF)) as compared with those of aprotic ionic liquids (APILs). The PILs used in this work are 1-methylimidazolium tetrafluoroborate, 2-methylpyridinium tetrafluoroborate, and N-methylpyrrolodinium tetrafluoroborate in comparison to 1-butyl-3-methylimidazolium tetrafluoroborate, which is classified as an APIL. In this work, the excess partial molar enthalpy, H(E)IL obtained from isothermal calorimetric titrations at 298.15 K is used to probe the nature of interactions of the PIL cations with solvent molecules against those present in APIL-solvent systems. This work also reports interesting flip-flopping in the thermal behavior of these PIL-solvent systems depending upon the structure of the cationic ring of a PIL. In some cases, these flip-flops are the specific fingerprints for specific PILs in a common solvent environment. The excess partial molar enthalpy at infinite dilution, H(E,?)IL, of these PILs bears a critical dependence on the solvent properties. An analysis of relative apparent molar enthalpies, ?L, of the PIL solutions by the ion interaction model of Pitzer yields important information on ionic interactions of these systems. PMID:24650134

Rai, Gitanjali; Kumar, Anil

2014-04-17

33

Corresponding States in Solutions of Ionic Liquids  

Microsoft Academic Search

Until recently, liquid-liquid phase transitions in ionic solutions were observed only on very few systems (1). The salts used were chemically rather unstable. Now, a great number of rather stable salts with melting points below 100°C, termed ionic liquids, are available. A substantial number of solutions of ionic liquids with a critical point at ambient temperatures have been discovered recently,

Wolffram Schröer; Annamaria Butka; Vlad Vale; Jan Köser

34

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

35

R&D of Energetic Ionic Liquids.  

National Technical Information Service (NTIS)

This presentation reviews current research and development of energetic ionic liquids, including state-of-the-art fuel, advanced chemical propulsion for spacecraft, history of energetic ionic liquids, and proposes 'greener' chemical propulsion via energet...

T. Hawkins

2011-01-01

36

Purification of gas with liquid ionic compounds  

US Patent & Trademark Office Database

The present invention provides a method for purifying a gas by contacting the gas with a liquid ionic compound. Natural gas may be purified, removing water and carbon dioxide, by contacting the natural gas with a liquid ionic compound.

2003-06-17

37

Ionic liquid functionalized Janus nanosheets.  

PubMed

Ionic liquid functionalized Janus nanosheets are synthesized by selective treatment of the imidazolin terminated side of Janus nanosheets while the other side is preserved. The Janus performance of the nanosheets and thus emulsion stability are reversibly triggered by anion exchange. PMID:24733114

Ji, Xuyang; Zhang, Qian; Liang, Fuxin; Chen, Qinan; Qu, Xiaozhong; Zhang, Chengliang; Wang, Qian; Li, Jiaoli; Song, Ximing; Yang, Zhenzhong

2014-06-01

38

Application of Ionic Liquids in Liquid Chromatography  

Microsoft Academic Search

Interest in ionic liquids (ILs) for their potential application in analytical chemistry continues to grow. Their usefulness can be due to favourable physicochemical properties, like the lack of vapour pressure, good thermal and chemical stability as well as very good dissolution properties regarding both organic and inorganic compounds. A specific feature of ILs is that these compounds provide strong proton

Micha? Piotr Marsza??; Roman Kaliszan

2007-01-01

39

Charge transport in confined ionic liquids  

NASA Astrophysics Data System (ADS)

Charge transport and glassy dynamics in neat and polymerized ionic liquids confined in nanoporous silica are investigated in a wide frequency and temperature ranges by a combination of Broadband Dielectric Spectroscopy and Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR). By applying the Einstein-Smoluchowski relations to the dielectric spectra, diffusion coefficients are obtained in quantitative agreement with independent PFG NMR. The impact of geometrical confinement as well as the pore wall-ionic liquid interactions on the overall ionic mobility is explored for diverse categories of ionic liquids. The results are discussed within the framework of dynamic glass transition assisted charge transport in ionic liquids.

Sangoro, Joshua; Iacob, Ciprian; Kipnusu, Wycliffe; Kremer, Friedrich

2011-03-01

40

Amphiphilic and phase-separable ionic liquids for biomass processing.  

PubMed

One main limiting factor for the technoeconomics of future bioprocesses that use ionic liquids (ILs) is the recovery of the expensive and potentially toxic IL. We have demonstrated a new series of phase-separable ionic liquids, based on the hydrophobic tetraalkylphosphonium cation ([PRRRR ](+) ), that can dissolve lignin in the neat state but also hemicellulose and high-purity cellulose in the form of their electrolyte solutions with dipolar aprotic solvents. For example, the IL trioctylmethylphosphonium acetate ([P8881 ][OAc]) was demonstrated to dissolve up to 19?wt?% of microcrystalline cellulose (MCC) at 60?°C with the addition of 40?wt?% of DMSO. It was found that the MCC saturation point is dependent on the molar ratio of DMSO and IL in solution. At the optimum saturation, a ?1:1 molar ratio of [P8881 ][OAc] to anhydroglucose units is observed, which demonstrates highly efficient solvation. This is attributed to the positive contribution that these more amphiphilic cation-anion pairs provide, in the context of the Lindman hypothesis. This effective dissolution is further illustrated by solution-state HSQC?NMR spectroscopy on MCC. Finally, it is also demonstrated that these electrolytes are phase separable by the addition of aqueous solutions. The addition of 10?% NaOAc solution allows a near quantitative recovery of high-purity [P8881 ][OAc]. However, increased volumes of aqueous solution reduced the recovery. The regenerated material was found to partially convert into the cellulose?II crystalline polymorph. PMID:24616349

Holding, Ashley J; Heikkilä, Mikko; Kilpeläinen, Ilkka; King, Alistair W T

2014-05-01

41

Ionic liquids for rechargeable lithium batteries  

Microsoft Academic Search

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, BMIMBF, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF-LiBF, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured

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

2005-01-01

42

Collisions of protic and aprotic gases with hydrogen bonding and hydrocarbon liquids  

Microsoft Academic Search

We explore collisions of Ne, CH4, NH3, and D2O with glycerol, a hydrogen bonding liquid, and with squalane, a liquid hydrocarbon. The experiments are carried out by directing a molecular beam at a continuously renewed liquid surface in vacuum and monitoring the identity and velocity of the scattered products with mass spectroscopy. We observe both direct inelastic scattering and trapping

Mary E. Saecker; Gilbert M. Nathanson

1993-01-01

43

Probing the mechanism of Baylis-Hillman reaction in ionic liquids.  

PubMed

The kinetic data for a Baylis-Hillman reaction in certain ionic liquids possessing ethylsulfate anion [EtSO(4)](-) demonstrate that the rate determining step (RDS) is second order in aldehyde, but first order in acrylate and DABCO. This observation is similar to the one made by McQuade et al., who carried out this reaction in an aprotic polar solvent like DMSO. However, this is in contrast to the general observation that RDS is first order in aldehyde, acrylate, and DABCO in organic solvents. PMID:22931044

Singh, Anshu; Kumar, Anil

2012-10-01

44

Ionic Liquid Crystals as Universal Matrices (Solvents)  

Microsoft Academic Search

\\u000a This paper is devoted to research on ionic liquid crystals in low-melting metal alkanoate systems, which may prove to be universal\\u000a solvents. The main criteria for ionic liquid crystal formation and stability have been established.

T. A. Mirnaya; S. V. Volkov

45

Modification of cationic nanoclays with ionic liquids  

Microsoft Academic Search

As part of a broader effort to develop nanoclays functionalized with different heterocyclic aromatic structures for novel applications, preliminary data are reported on the modification of sodium montmorillonite, a cationic clay, with three low molecular weight pyridinium- and imidazolium-based ionic liquids. Commercially available unmodified clay was treated under different conditions with aqueous solutions of three ionic liquids: N-ethyl pyridinium tetrafluoroborate,

Neung Hyun Kim; Sanjay V. Malhotra; Marino Xanthos

2006-01-01

46

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

2011-06-14

47

The Solubility Parameters of Ionic Liquids  

PubMed Central

The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated.

Marciniak, Andrzej

2010-01-01

48

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

49

Ionic liquid stationary phases for gas chromatography.  

PubMed

This article provides a summary of the development of ionic liquids as stationary phases for gas chromatography beginning with early work on packed columns that established details of the retention mechanism and established working methods to characterize selectivity differences compared with molecular stationary phases through the modern development of multi-centered cation and cross-linked ionic liquids for high-temperature applications in capillary gas chromatography. Since there are many reviews on ionic liquids dealing with all aspects of their chemical and physical properties, the emphasis in this article is placed on the role of gas chromatography played in the design of ionic liquids of low melting point, high thermal stability, high viscosity, and variable selectivity for separations. Ionic liquids provide unprecedented opportunities for extending the selectivity range and temperature-operating range of columns for gas chromatography, an area of separation science that has otherwise been almost stagnant for over a decade. PMID:21290604

Poole, Colin F; Poole, Salwa K

2011-04-01

50

Ionic Liquids as Catalysts for Ethylbenzene Production  

Microsoft Academic Search

\\u000a Chloroaluminate ionic liquids have been assessed as liquid acid catalysts for the alkylation of benzene with ethylene to produce\\u000a ethylbenzene. Detailed comparisons with commercial aluminium(III) chloride catalyst have been carried out, using performance\\u000a indicators such as activity, selectivity and lifetime. Results of the study indicate inferior activity but superior recyclability\\u000a with current generations of ionic liquid catalysts. Calculations suggest that

M. P. Atkins; C. Bowlas; B. Ellis; F. Hubert; A. Rubatto; P. Wasserscheid

51

Ionic liquids for energy, materials, and medicine.  

PubMed

As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today. PMID:24830849

Smiglak, M; Pringle, J M; Lu, X; Han, L; Zhang, S; Gao, H; MacFarlane, D R; Rogers, R D

2014-07-22

52

Design and synthesis of photoactive ionic liquids.  

PubMed

Two ionic liquids with photoisomerizable p-hydroxycinnamic acid moieties were synthesized and characterized by X-ray crystallography and DSC, and their photochemistry was studied in solution and neat conditions. Irradiation at absorption maxima led to trans-cis photoisomerization and resulted in significant reduction of melting temperatures of the ionic liquids. X-ray structures of both compounds show an intricate network of supramolecular interactions before irradiation. Physical and chemical transformations are completely reversible upon irradiation at lower wavelengths of ionic liquid solutions in acetonitrile. PMID:24787141

Avó, João; Cunha-Silva, Luís; Lima, João Carlos; Jorge Parola, A

2014-05-16

53

Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal  

PubMed Central

The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

2014-01-01

54

Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal.  

PubMed

The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide. PMID:24790972

Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

2014-01-01

55

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

56

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

57

Vibrational spectroscopic study of ionic liquids: Comparison between monocationic and dicationic imidazolium ionic liquids  

NASA Astrophysics Data System (ADS)

In this study, we synthesised a dicationic ionic liquids labeled bis-methyl imidazolium methylidene bis (trifluoromethanesulfonyl) imide ([M(CH2)IM2+][2NTf2-]). The structure was identified by NMR. In order to characterise this ionic liquid, vibrational spectroscopy studies were performed by FTIR/ATR and FT-Raman spectroscopies. A comparative study was introduced by FTIR/ATR and FT-Raman spectroscopies, between our synthesised dicationic ionic liquid and a monocationic ionic liquid ([EMIM+][NTf2-]), where the anion and the cation are similar.

Moumene, Taqiyeddine; Belarbi, El Habib; Haddad, Boumediene; Villemin, Didier; Abbas, Ouissam; Khelifa, Brahim; Bresson, Serge

2014-05-01

58

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

59

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

2005-12-30

60

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

2006-01-01

61

Study of thioglycosylation in ionic liquids  

PubMed Central

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.

Zhang, Jianguo; Ragauskas, Arthur

2006-01-01

62

Quinones electrochemistry in room-temperature ionic liquids.  

PubMed

The two-step electrochemical reduction of tetrachloro-1,2-benzoquinone (chloranil), 2-methyl-1,2-benzoquinone (toluquinone), and 9,10-anthraquinone in two room-temperature ionic liquids is addressed by means of voltammetry on a platinum electrode. For the subsequent quinone/radical anion (Q/Q(•-)) and radical anion/dianion (Q(•-)/Q(2-)) redox reactions, the experimental data on formal potentials in 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF(4)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]) and literature data for the same reactants in various aprotic molecular solvents are considered in the framework of a common potential sequence (Fc(+)/Fc scale) and compared with solvation energies computed at various levels. For the Q/Q(•-) couple, the agreement appeared to be satisfactory when solvation is described at the polarized continuum model (PCM) level. In contrast, for the Q(•-)/Q(2-) couple, the account for specific solvation at the molecular level is crucial. PMID:21155587

Nikitina, Viktoriya A; Nazmutdinov, Renat R; Tsirlina, Galina A

2011-02-01

63

Behavior of electrogenerated bases in room-temperature ionic liquids.  

PubMed

The reductive electrochemistry of substituted benzophenones in the aprotic room-temperature ionic liquid (RTIL) 1-butyl-1-methylpyrrolidinium bistriflimide occurs via two consecutive one-electron processes leading to the radical anion and dianion, respectively. The radical anion exhibited electrochemical reversibility at all time-scales whereas the dianion exhibited reversibility at potential sweep rates of >or=10 V s(-1), collectively indicating the absence of strong ion-paring with the RTIL cation. In contrast, reduction in 1-butyl-3-methylimidazolium bistriflimide is complicated by proton-transfer from the [Bmim] cation. At low potential sweep rates, reduction involves a single two-electron process characteristic of either an electrochemical, chemical, electrochemical (ECE) or disproportion-type (DISP1) mechanism. The rate of radical anion protonation in [Bmim] is governed by basicity and conforms to the Hammett free-energy relation. At higher potential sweep rates in [Bmim][NTf2], reduction occurs via two consecutive one-electron processes, giving rise to the partially reversible generation of the radical anion and the irreversible generation of the dianion, respectively. Also, the redox potentials for the reversible parent/radical anion couples were found to be a linear function of Hammett substituent constants in both RTIL media and exhibited effectively equivalent solvent-dependent reaction constants, which are similar to those for reduction in polar molecular solvents such as acetonitrile or alcohols. PMID:17630791

O'Toole, Sarah; Pentlavalli, Sreekanth; Doherty, Andrew P

2007-08-01

64

Pseudocapacitance of MnO 2 originates from reversible insertion\\/desertion of thiocyanate anions studied using in situ X-ray absorption spectroscopy in ionic liquid electrolyte  

Microsoft Academic Search

Charge storage mechanisms of electrodeposited MnO2 in various aprotic ionic liquids (ILs) are studied using in situ X-ray absorption spectroscopy (XAS). The analytical results show that a unique thiocyanate (SCN?) anion can reversibly insert\\/desert into\\/from the tunnels between the [MnO6] octahedral subunits depending on the applied potential. This process charge compensates the Mn3+\\/Mn4+ redox transition upon charging–discharging and thus contributes

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

2010-01-01

65

Dissolution of wood in ionic liquids.  

PubMed

The present paper demonstrates that both hardwoods and softwoods are readily soluble in various imidazolium-based ionic liquids (ILs) under gentle conditions. More specifically, a variety of ionic liquids can only partially dissolve wood chips, whereas ionic liquids such as 1-butyl-3-methylimidazolium chloride and 1-allyl-3-methylimidazolium chloride have good solvating power for Norway spruce sawdust and Norway spruce and Southern pine thermomechanical pulp (TMP) fibers. Despite the fact that the obtained solutions were not fully clear, these ionic liquids provided solutions which permitted the complete acetylation of the wood. Alternatively, transparent amber solutions of wood could be obtained when the dissolution of the same lignocellulosic samples was attempted in 1-benzyl-3-methylimidazolium chloride. This realization was based on a designed augmented interaction of the aromatic character of the cation of the ionic liquid with the lignin in the wood. After dissolution, wood can be regenerated as an amorphous mixture of its original components. The cellulose of the regenerated wood can be efficiently digested to glucose by a cellulase enzymatic hydrolysis treatment. Furthermore, completely acetylated wood was found to be readily soluble in chloroform, allowing, for the first time, detailed proton nuclear magnetic resonance (NMR) spectra and NMR diffusion measurements to be made. It was thus demonstrated that the dissolution of wood in ionic liquids now offers a variety of new possibilities for its structural and macromolecular characterization, without the prior isolation of its individual components. Furthermore, considering the relatively wide solubility and compatibility of ionic liquids with many organic or inorganic functional chemicals or polymers, it is envisaged that this research could create a variety of new strategies for converting abundant woody biomass to valuable biofuels, chemicals, and novel functional composite biomaterials. PMID:17907779

Kilpeläinen, Ilkka; Xie, Haibo; King, Alistair; Granstrom, Mari; Heikkinen, Sami; Argyropoulos, Dimitris S

2007-10-31

66

Mixtures of protic ionic liquids and molecular cosolvents: A molecular dynamics simulation.  

PubMed

In this work, the effect of molecular cosolvents (water, ethanol, and methanol) on the structure of mixtures of these compounds with a protic ionic liquid (ethylammonium nitrate) is analyzed by means of classical molecular dynamics simulations. Included are as-yet-unreported measurements of the densities of these mixtures, used to test our parameterized potential. The evolution of the structure of the mixtures throughout the concentration range is reported by means of the calculation of coordination numbers and the fraction of hydrogen bonds in the system, together with radial and spatial distribution functions for the various molecular species and molecular ions in the mixture. The overall picture indicates a homogeneous mixing process of added cosolvent molecules, which progressively accommodate themselves in the network of hydrogen bonds of the protic ionic liquid, contrarily to what has been reported for their aprotic counterparts. Moreover, no water clustering similar to that in aprotic mixtures is detected in protic aqueous mixtures, but a somehow abrupt replacing of [NO3](-) anions in the first hydration shell of the polar heads of the ionic liquid cations is registered around 60% water molar concentration. The spatial distribution functions of water and alcohols differ in the coordination type, since water coordinates with [NO3](-) in a bidentate fashion in the equatorial plane of the anion, while alcohols do it in a monodentate fashion, competing for the oxygen atoms of the anion. Finally, the collision times of the different cosolvent molecules are also reported by calculating their velocity autocorrelation functions, and a caging effect is observed for water molecules but not in alcohol mixtures. PMID:24908021

Docampo-Álvarez, Borja; Gómez-González, Víctor; Méndez-Morales, Trinidad; Carrete, Jesús; Rodríguez, Julio R; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M

2014-06-01

67

Electrically Switchable Capillarity of Ionic Liquids  

Microsoft Academic Search

Electrocapillarity is the basis of modern electrowetting. And room temperature ionic liquids, an increasingly important set of electrolytes and organic salts that are liquid at room temperature, are considered a novel class of electrowetting agents, because of non-significant vapor pressure, nonflammability, good thermal stability, and a wide useable temperature range. In this paper, a simple device has been fabricated to

Xiaodong Hu; Shiguo Zhang; Chao Qu; Qinghua Zhang; Liujin Lu; Xiangyuan Ma; Xiaoping Zhang; Youquan Deng

2012-01-01

68

Ionic liquids: new perspectives for inorganic synthesis?  

PubMed

Ionic liquids are credited with a number of unusual properties. These include a low vapor pressure, a wide liquid-phase range, weakly coordinating properties, and a high thermal/chemical stability. These properties are certainly of great interest for inorganic synthesis and the creation of novel inorganic compounds. On the other hand, the synthesis repertoire for preparing inorganic compounds has always been broad, ranging from syntheses in solutions and melts to solid-state reactions, and from crystal growth in the gas phase to high-pressure syntheses. What new aspects can ionic liquids then add to the synthesis of inorganic compounds? This Minireview uses some early examples to show that the use of ionic liquids indeed provides access to unusual inorganic compounds. PMID:21990270

Freudenmann, Dominic; Wolf, Silke; Wolff, Michael; Feldmann, Claus

2011-11-18

69

Surface Nanocrystallization of an Ionic Liquid  

NASA Astrophysics Data System (ADS)

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

2012-02-01

70

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

2011-06-01

71

Polymer electrolyte with ionic liquid for DSSC application  

Microsoft Academic Search

We have investigated the structural and ionic conductivity properties of the polymer electrolyte PEO:KI\\/I2 doped with an ionic liquid 1-ethyl 3-methylimidazolium thio-cyanate (EMImSCN). Incorporation of the ionic liquid (IL) reduced the crystallinity, and enhanced the ionic conductivity. Optimized conductivity was found at 80 wt% of ionic liquid composition. This high electrical conductivity was suitable for dye sensitized solar cell (DSSC)

Pramod K. Singh; Ki-Il Kim; Jae-Wook Lee; Hee-Woo Rhee

2006-01-01

72

Soft Ionization of Thermally Evaporated Hypergolic Ionic Liquid Aerosols.  

National Technical Information Service (NTIS)

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 vaporizin...

A. Golan C. Harmon C. Liu C. J. Koh D. Strasser

2011-01-01

73

Gelation, functionalization, and solution behaviors of nanodiamonds with ionic liquids.  

PubMed

Detonation nanodiamond particles can be formed a gel with ionic liquids, which can easily be fabricated. The imidazolium bromide-functionalized nanodiamond particles are dispersed in ionic liquids with uniform size-distribution. PMID:19753362

Park, Cho-Long; Jee, Ah Young; Lee, Minyung; Lee, Sang-gi

2009-10-01

74

Probing Local Environments in Ionic Liquids  

NASA Astrophysics Data System (ADS)

The polarity and solvation properties were investigated for four ionic liquids with non-aromatic cation. The four ionic liquids studied were: N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)-imide (Pyrr14+/NTf2-), N-methyl-N-ethoxyethylpyrrolidinium bis(trifluoromethylsulfonyl)-imide (Pyrr1(202)+/NTf2-), N-methyl-tri-N-butylammonium bis(trifluoromethylsulfonyl) -imide (N1444+/NTf2-) and N-hexyl-tri-N-butylammonium bis(trifluoromethylsulfonyl) -imide (N6444+/NTf2-). The ammonium based ILs exhibit slightly higher polarity than pyrrolidinium based ILs. The solvation dynamics of the fluorescence probe molecule Coumarin 153 exhibits multi-exponential character in all four ILs. The observed solvation dynamics occur on timescales orders of magnitude longer than for most organic solvents. The reorientational dynamics investigated by method of time-resolved fluorescence anisotropy decay is faster than predicted by hydrodynamic theory. The ionic liquid/water interaction were characterized for hydrophobic and water- miscible ionic liquids. The two ionic liquids studied were: 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (Pyrr14+ /NTf 2-) and 1-butyl-1-methylpyrrolidinium Trifloromethylsulfonate (Pyrr14+/OTf-). The concentration dependence of water proton chemical shift deltaH2O reveals different water-anion interaction in these two ILs. The diffusion properties were investigated in the system IL/water by pulse gradient DOSY experiments. The diffusional behavior of cations and anions is very similar whereas water exhibits anomalously high diffusion rate. The diffusional properties of water are different in two ILs. The ratio D H2O / Dcation is higher for more hydrophobic Pyrr14 + /NTf2- that confirms weaker water-anion interaction in this liquid.

Fadeeva, Tatiana A.

75

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

76

Ionic Transport in Liquid Silicates  

Microsoft Academic Search

OME uncertainty exists concerning the presence of semi­ conduction in the electric conduction of liquid silicates. This may be resolved only by measurements of the applicability of Faraday's Laws to the electric transport processes in the melt. Such measurements are considered to be difficult at 800°C in liquid salts.' A method has been devised in these laboratories whereby the oxygen

J. O'M. Bockris; J. A. Kitchener; A. E. Davies

1951-01-01

77

New developments in catalysis using ionic liquids  

Microsoft Academic Search

Ionic liquids are low melting point salts that represent an exciting new class of reaction solvents for catalysis. Being composed entirely of ions, they possess negligible vapour pressures, and the wide range of possible cations and anions means that other solvent properties may be easily controlled. There is currently great interest in the use of these materials as solvents for

Charles M. Gordon

2001-01-01

78

Biocatalysis in ionic liquids – advantages beyond green technology  

Microsoft Academic Search

In recent years researchers have started to explore a particular class of organic solvents called room temperature ionic liquids — or simply ionic liquids – to identify their unique advantages for biocatalysis. Because they lack vapour pressure, ionic liquids hold potential as green solvents. Furthermore, unlike organic solvents of comparable polarity, they often do not inactivate enzymes, which simplifies reactions

Romas J Kazlauskas

2003-01-01

79

Electrofluorochromism in ?-conjugated ionic liquid crystals  

NASA Astrophysics Data System (ADS)

Materials in which photoluminescence is modulated by redox processes are known as electrofluorochromic. Intrinsically switchable fluorophores, incorporating both redox and fluorescent moieties, could be ideal electrofluorochromic materials if they possess high fluorescence quantum yields in at least one of their redox states. Fluorescent liquid crystals with redox active centres could combine the above requirements with the advantage to work in bulk anisotropic phases. However, electrofluorochromic liquid crystals have not been reported yet because their synthesis is challenging due to aggregation-caused fluorescent quenching. Here we show the first examples of electrofluorochromic ?-conjugated ionic liquid crystals based on thienoviologens. These ordered materials, combining ionic and electronic functions, are highly fluorescence in the bulk state (quantum yield>60%). Their direct electrochemical reduction leads to fast and reversible bulk electrofluorochromic response in both columnar and smectic phases allowing for fluorescence intensity modulation and colour tuning.

Beneduci, Amerigo; Cospito, Sante; La Deda, Massimo; Veltri, Lucia; Chidichimo, Giuseppe

2014-01-01

80

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

2011-12-23

81

Synthetic organic electrochemistry in ionic liquids: the viscosity question.  

PubMed

Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved. PMID:21769062

Bornemann, Steven; Handy, Scott T

2011-01-01

82

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

83

Ionic liquid sensitized fluorescence determination of four isoquinoline alkaloids  

Microsoft Academic Search

The fluorescence spectra of berberine, palmatine, jatrorrhizine, and coptisine in ionic liquids were studied and found to increase significantly in ionic liquids, with [C8MIM][PF6] having the greatest increase. Further studies showed that these drugs could be extracted from an aqueous solution by [C8MIM][PF6] using the temperature-assisted ionic liquid dispersive liquid phase microextraction method. The enrichment factors were 81.8–82.3, and the

Hao Wu; Li-bing Zhang; Li-ming Du

2011-01-01

84

Room temperature ionic liquid as a novel medium for liquid\\/liquid extraction of metal ions  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) have been used as novel solvents to replace traditional volatile organic solvents in organic synthesis, solvent extraction, and electrochemistry. The hydrophobic character and water immiscibility of certain ionic liquids allow their use in solvent extraction of hydrophobic compounds. In this work, a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], was used as an alternative

Guor-Tzo Wei; Zusing Yang; Chao-Jung Chen

2003-01-01

85

Polymer-supported ionic-liquid-like phases (SILLPs): transferring ionic liquid properties to polymeric matrices.  

PubMed

The physico-chemical properties of polymers with ionic-liquid-like moieties covalently bound to their surfaces (SILLPs) have been studied by thermal and spectroscopic techniques, as well as by direct impedance and dielectric measurements, and compared to those of the corresponding bulk ionic liquids. The effective transfer of properties from ionic liquids in solution to the supported species has thereby been demonstrated. The effects of the chemical nature of these tunable "solid solvents" on their macroscopic swelling and microwave heating, as well as the stabilities and activities of different catalytic moieties immobilized on the SILLPs, have been studied. Finally, the experimental effect observed in microwave heating can be directly correlated with the values of tan ? derived from dielectric measurements. PMID:21274940

Sans, Victor; Karbass, Naima; Burguete, M Isabel; Compañ, Vicente; García-Verdugo, Eduardo; Luis, Santiago V; Pawlak, Milena

2011-02-01

86

Ionic Liquids as a Medium for Ionic Chain Polymerizations: An Environmentally Responsible Approach to Macromolecular Synthesis with Controlled Architecture.  

National Technical Information Service (NTIS)

This Short Term Innovation Research proposal set out to explore the possible advantages of using ionic liquids as a medium for ionic polymerizations. The first anionic, living polymerization in an ionic liquid medium was accomplished. Reaction conditions ...

S. Gross

2004-01-01

87

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

88

Homopolymer Dissolution in a Hydrophilic Ionic Liquid  

NASA Astrophysics Data System (ADS)

Dissolution, structure, and dynamics of both neutral and charged polymers dissolved in a hydrophilic room temperature ionic liquid (IL), ethylmethylimidazolium ethyl sulfate [EMIM][EtSO4], have been studied by classical physicochemical methods (static and dynamic light scattering, intrinsic viscosity, refractometry) to determine differences in solution behavior from conventional aqueous and organic solvents. This IL is water miscible. Many neutral polymers and charged polymer salts molecularly dissolve, although solubility doesn't correlate with polymer hydrophilicity. Model neutral soluble polymers are polyvinylpyrrolidone and hydroroxyethyl cellulose while sodium poly(styrene sulfonate) and the iodo salt of methyl-quaternized poly(vinyl pyridine) fill the same role for charged polymers. The latter display none of the polyelectrolyte effects found in low ionic strength water, consistent with strong electrostatic screening in IL. In virial coefficient and coil size, the IL acts for these neutral and charged polymers as a classical good solvent. (Support: UMass MRSEC)

Hoagland, David; Harner, John

2010-03-01

89

Evaporation from an ionic liquid emulsion.  

PubMed

The conditions during evaporation in a liquid crystal-in-ionic liquid microemulsion (LC/microEm) were estimated using the phase diagram of the system. The equations for selected tie lines were established and the coordinates calculated for the sites, at which the evaporation lines crossed the tie lines. These values combined with the coordinates for the phases connecting the tie lines were used to calculate the amounts and the composition of the fractions of the two phases present in the emulsion during the evaporation. One of the emulsion phases was a lamellar liquid crystal and high energy emulsification would lead to the liquid crystal being disrupted to form vesicles. Such a system tenders a unique opportunity to study the interaction between vesicles and normal micelles, which gradually change to inverse micelles over bi-continuous structures. The amount of vesicles in the liquid phase versus the fraction liquid crystal was calculated for two extreme cases of vesicle core size and shell thickness. The limit of evaporation while retaining the vesicle structure was calculated for emulsions of different original compositions assuming the minimum continuous liquid phase to be 50% of the emulsion. PMID:17207810

Friberg, Stig E

2007-03-15

90

Supramolecular gelators based on benzenetricarboxamides for ionic liquids.  

PubMed

Supramolecular gelators comprising 1,3,5-benzenetricarboxylic acids and amino acid methyl esters (glycine, l-alanine, l-valine, l-leucine, l-methionine, and l-phenylalanine) for ionic liquids were developed. Ten types of ionic liquids were gelated using the above-mentioned gelators at relatively low concentrations. Field emission-scanning electron microscopy and confocal laser scanning microscopy analyses revealed that these gelators self-assembled into an entangled fibrous structure in ionic liquids, leading to the gelation of the ionic liquids. Comparison studies, involving compounds analogous to the gelators, and Fourier transform infrared spectroscopy measurements suggested that hydrogen bonding played a key role in the self-assembly of the gelator molecules. The ionogels displayed reversible thermal transition characteristics and viscoelastic properties typical of a gel. The gelation of the ionic liquids studied under a wide range of gelator concentrations did not affect the intrinsic conductivity of the ionic liquids. PMID:24652194

Ishioka, Yumi; Minakuchi, Nami; Mizuhata, Minoru; Maruyama, Tatsuo

2014-01-22

91

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

2012-11-01

92

Ionic Liquid Structure-Induced Effects on Organic Reactions  

NASA Astrophysics Data System (ADS)

Understanding the ways in which the constituents of ionic liquids, i.e. the type of cation, its substitution, and the type of anion chosen, interact with reactants is prerequisite to deliberately designing an ionic liquid solvent with optimum performance. Several approaches, including physico-chemical and spectroscopic measurements and computational studies of binary ionic liquid-substrate mixtures have been presented that investigate the strength of interactions.

Stark, Annegret

93

Factors Influencing Electrochemical Actuation of Polyaniline Fibers in Ionic Liquids  

Microsoft Academic Search

Room-temperature ionic liquids have been demonstrated to be advantageous in the development of conducting polymer electrochemical devices. In this paper, we fabricated electrochemical actuators using polyaniline fibers and ionic liquid electrolytes and investigated factors that influence their actuation performance in the ionic liquid [BMIM][BF4], such as the dopant anion, conductive and mechanical properties of the polyaniline fibers, external load, and

Wen Lu; Benjamin R. Mattes

2005-01-01

94

Durable electrooptic devices comprising ionic liquids  

DOEpatents

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF3SO3-), bis(trifluoromethylsulfonyl)imide ((CF3SO2)2N-), bis(perfluoroethylsulfonyl)imide ((CF3CF2SO2)2N-) and tris(trifluoromethylsulfonyl)methide ((CF3SO2)3C-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM); Burrell, Anthony K. (Los Alamos, NM)

2005-11-01

95

Ionic Liquids and Ionizing Radiation: Reactivity of Highly Energetic Species  

SciTech Connect

Due to their unique properties, ionic liquids present many opportunities for basic research on the interactions of radiation with materials under conditions not previously available. At the same time, there are practical applied reasons for characterizing, understanding, and being able to predict how ionic-liquid-based devices and industrial-scale systems will perform under conditions of extreme reactivity, including radiation. This perspective discusses current issues in ionic liquid physical chemistry, provides a brief introduction to radiation chemistry, draws attention to some key findings in ionic liquid radiation chemistry, and identifies some current hot topics and new opportunities.

Wishart, J.F.

2010-11-04

96

Highly luminescent and color-tunable salicylate ionic liquids.  

PubMed

High quantum yields of up to 40.5% can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cation-anion pairing interactions. Facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow. PMID:24615781

Campbell, Paul S; Yang, Mei; Pitz, Demian; Cybinska, Joanna; Mudring, Anja-Verena

2014-04-14

97

Oxygen Extraction from Regolith Using Ionic Liquids  

NASA Technical Reports Server (NTRS)

An important concern with long-duration manned space travel is the need to furnish enough materials to the vehicle, as well as the crew, for the duration of the mission. By extracting oxygen from the oxides present in regolith, propellant and life support could be supplied to the vehicle and the crew while in space, thereby limiting the amount of supplies needed prior to lift-off. Using a class of compounds known as ionic liquids, we have been able to lower the electrolysis operating temperature from 1600 C (molten oxide electrolysis) to less than 200 C, making this process much more feasible in terms of energy consumption and materials handling. To make this process ready for deployment into space, we have investigated what steps of the process would be affected by the low-gravity environment in space. In the lab, the solubilization of lunar regolith simulant in ionic liquid produces water vapor that is normally distilled out of solution and subsequently electrolyzed for oxygen production. This distillation is not possible in space, so we have tested a method known as pervaporation and have suggested a way this technique could be incorporated into a reactor design.

Barrios, Elizabeth A.; Curreri, Peter A.; Karr, Laurel J.

2011-01-01

98

Toxicity of ionic liquids prepared from biomaterials.  

PubMed

In search of environmentally-friendly ionic liquids (ILs), 14 were prepared based on the imidazolium, pyridinium and choline cations, with bromide and several amino acids as anions. Good yields were obtained in the synthesis of pyridinium ILs and those prepared from choline and amino acids. Four of the ILs synthesized from choline and the amino acids arginine, glutamine, glutamic acid and cystine are described here for the first time. The toxicity of the synthesized ILs was checked against organisms of various levels of organization: the crustacean Artemia salina; Human cell HeLa (cervical carcinoma); and bacteria with different types of cell wall, Bacillus subtilis and Escherichia coli. The toxicity was observed to depend on both the cation and anion. Choline-amino acid ILs showed a remarkable low toxicity to A. salina and HeLa cell culture, ten times less than imidazolium and pyridinium ILs. None of ionic liquids exhibited marked toxicity to bacteria, and the effect was 2-3 orders of magnitude smaller than that of the antibiotic chloramphenicol. PMID:24268343

Gouveia, W; Jorge, T F; Martins, S; Meireles, M; Carolino, M; Cruz, C; Almeida, T V; Araújo, M E M

2014-06-01

99

Nonconvective mixing of miscible ionic liquids.  

PubMed

Ionic liquids (ILs) are ionic compounds that are liquid at room temperature. We studied the spontaneous mixing behavior between two ILs, ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and observed notable phenomena. Experimental studies showed that the interface between the two ILs was unusually long-lived, despite the ILs being miscible with one another. Molecular dynamics (MD) simulations supported these findings and provided insight into the micromixing behavior of the ILs. We found that not only did the ions experience slow diffusion as they mix but also exhibited significant ordering into distinct regions. We suspect that this ordering disrupted concentration gradients in the direction normal to the interface, thus hindering diffusion in this direction and allowing the macroscopic interface to remain for long periods of time. Intermolecular interactions responsible for this behavior included the O-NH interaction between the EAN ions and the carbon chain-carbon chain interactions between the [BMIM](+) cations, which associate more strongly in the mixed state than in the pure IL state. PMID:23855707

Frost, Denzil S; Machas, Michael; Perea, Brian; Dai, Lenore L

2013-08-13

100

Boundary layer charge dynamics in ionic liquid-ionic polymer transducers  

NASA Astrophysics Data System (ADS)

Ionic polymer transducers (IPTs), also known as ionic polymer-metal composites, are soft sensors and actuators which operate through a coupling of microscale 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 apply Nernst-Planck/Poisson theory to model charge transport in an ionic liquid IPT by considering a certain fraction of the ionic liquid ions as mobile charge carriers, a phenomenon which is unique to ionic liquid IPTs compared to their water-based counterparts. Numerical simulations are performed using the finite element method to examine how the introduction of another pair of mobile ions affects boundary layer charge dynamics, concentration, and charge density distributions in the electric double layer, and the overall charge transferred and current response of the IPT. Due to interactions with the Nafion ionomer, not all of the ionic liquid ions will function as mobile charge carriers; only a certain fraction will exist as ``free'' ions. The presence of mobile ionic liquid ions in the transducer will increase the overall charge transferred when a voltage is applied, and cause the current in the transducer to decay more slowly. The additional mobile ions also cause the ionic concentration profiles to exhibit a nonlinear dynamic response, characterized by nonmonotonic ionic concentration profiles in space and time. Although the presence of mobile ionic liquid ions increases the overall amount of charge transferred, this additional charge transfer occurs in a somewhat symmetric manner. Therefore, the additional charge transferred due to the ionic liquid ions does not greatly increase the net bending moment of the transducer; in fact, it is possible that ionic liquid ion movement actually decreases the observed bending response. This suggests that an optimal electromechanical conversion efficiency for bending actuation is achieved by using an ionic liquid where only a relatively small fraction of the ionic liquid ions exist as free ions. Conversely, if it is desired to increase the overall amount of charge transferred, an ionic liquid with a large fraction of free ions should be used. These theoretical considerations are found to be in good qualitative agreement with recent experimental results.

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

2011-01-01

101

Determination of an acidic scale in room temperature ionic liquids.  

PubMed

The acidity scale of different Brønsted acids in ionic liquids such as [BMIM][NTf2], [BMIM][BF4], and [BMMIM][BF4] has been investigated by determination of Hammett functions, using a spectrophotometric indicator method. This scale should permit one to correlate the acidity strength of ionic liquid systems with their ability to achieve acid-catalyzed reactions. PMID:12720424

Thomazeau, Cécile; Olivier-Bourbigou, Hélène; Magna, Lionel; Luts, Stéphane; Gilbert, Bernard

2003-05-01

102

Sorption of imidazolium-based ionic liquids to aquatic sediments  

Microsoft Academic Search

Ionic liquids (ILs) have received much attention as “green” alternatives to traditional solvents because they do not evaporate, eliminating concerns over fugitive emissions. However, if ionic liquids are used in industrial applications, they may enter aquatic systems via effluent, and their fate and transport may be influenced by sorption to sediments. In this study, we conducted batch mixing experiments with

J. J. Beaulieu; J. L. Tank; M. Kopacz

2008-01-01

103

Limited thermal stability of imidazolium and pyrrolidinium ionic liquids  

SciTech Connect

Ionic liquids, with their vast applications, have been touted as being thermally stable to very high temperatures. However, decomposition not detected by standard TGA and NMR techniques are observed with spectroscopic techniques sensitive enough to see small amounts of impurities. Decomposition temperatures of common ionic liquids appear to occur at hundreds of degrees below those temperatures previously reported.

Del Sesto, Rico E [Los Alamos National Laboratory (LANL); Mccleskey, T [Los Alamos National Laboratory (LANL); Macomber, Clay [Los Alamos National Laboratory (LANL); Ott, Kevin [Los Alamos National Laboratory (LANL); Koppisch, Andrew [Los Alamos National Laboratory (LANL); Baker, Gary A [ORNL; Burrell, Anthony K [ORNL

2009-01-01

104

Advances in chiral ionic liquids derived from natural amino acids  

Microsoft Academic Search

Ionic liquids (ILs) possess a number of unique properties; hence they have received much interest as green media for synthesis, analysis, catalysis, separation, and energy provision. More recently, chiral ionic liquids (CILs), which are derived from natural amino acids with chirality, biodegradability, reduced toxicity, and high biocompatibility, have also attracted interest. This report provides an overview of the design, synthesis,

Xuewei Chen; Xuehui Li; Aixi Hu; Furong Wang

2008-01-01

105

Structure and magnetic behavior of transition metal based ionic liquids  

SciTech Connect

A series of ionic liquids containing different paramagnetic anions have been prepared and all show paramagnetic behavior with potential applications for magnetic and electrochromic switching as well as novel magnetic transport; also, the tetraalkylphosphonium-based ionic liquids reveal anomalous magnetic behavior.

Del Sesto, Rico E [Los Alamos National Laboratory (LANL); Mccleskey, T [Los Alamos National Laboratory (LANL); Burrell, Anthony K [ORNL; Baker, Gary A [ORNL; Thompson, Joe D. [Los Alamos National Laboratory (LANL); Scott, Brian L. [Los Alamos National Laboratory (LANL); Wilkes, John S [United States Air Force Academy (USAFA), Colorado; Williams, Peg [United States Air Force Academy (USAFA), Colorado

2008-01-01

106

The Hildebrand Solubility Parameters of Ionic Liquids--Part 2  

PubMed Central

The Hildebrand solubility parameters have been calculated for eight ionic liquids. Retention data from the inverse gas chromatography measurements of the activity coefficients at infinite dilution were used for the calculation. From the solubility parameters, the enthalpies of vaporization of ionic liquids were estimated. Results are compared with solubility parameters estimated by different methods.

Marciniak, Andrzej

2011-01-01

107

Magnetic nanoparticles supported ionic liquids improve firefly luciferase properties.  

PubMed

Ionic liquids as neoteric solvents, microwave irradiation, and alternative energy source are becoming as a solvent for many enzymatic reactions. We recently showed that the incubation of firefly luciferase from Photinus pyralis with various ionic liquids increased the activity and stability of luciferase. Magnetic nanoparticles supported ionic liquids have been obtained by covalent bonding of ionic liquids-silane on magnetic silica nanoparticles. In the present study, the effects of [?-Fe2O3@SiO2][BMImCl] and [?-Fe2O3@SiO2][BMImI] were investigated on the structural properties and function of luciferase using circular dichroism, fluorescence spectroscopy, and bioluminescence assay. Enzyme activity and structural stability increased in the presence of magnetic nanoparticles supported ionic liquids. Furthermore, the effect of ingredients which were used was not considerable on K(m) value of luciferase for adenosine-5'-triphosphate and also K(m) value for luciferin. PMID:24492953

Noori, Ali Reza; Hosseinkhani, Saman; Ghiasi, Parisa; Akbari, Jafar; Heydari, Akbar

2014-03-01

108

Nonaborane and decaborane cluster anions can enhance the ignition delay in hypergolic ionic liquids and induce hypergolicity in molecular solvents.  

PubMed

The dissolution of nido-decaborane, B10H14, in ionic liquids that are hypergolic (fuels that spontaneously ignite upon contact with an appropriate oxidizer), 1-butyl-3-methylimidazolium dicyanamide, 1-methyl-4-amino-1,2,4-triazolium dicyanamide, and 1-allyl-3-methylimidazolium dicyanamide, led to the in situ generation of a nonaborane cluster anion, [B9H14](-), and reductions in ignition delays for the ionic liquids suggesting salts of borane anions could enhance hypergolic properties of ionic liquids. To explore these results, four salts based on [B10H13](-) and [B9H14](-), triethylammonium nido-decaborane, tetraethylammonium nido-decaborane, 1-ethyl-3-methylimidazolium arachno-nonaborane, and N-butyl-N-methyl-pyrrolidinium arachano-nonaborane were synthesized from nido-decaborane by reaction of triethylamine or tetraethylammonium hydroxide with nido-decaborane in the case of salts containing the decaborane anion or via metathesis reactions between sodium nonaborane (Na[B9H14]) and the corresponding organic chloride in the case of the salts containing the nonaborane anion. These borane cluster anion salts form stable solutions in some combustible polar aprotic solvents such as tetrahydrofuran and ethyl acetate and trigger hypergolic reactivity of these solutions. Solutions of these salts in polar protic solvents are not hypergolic. PMID:24716643

McCrary, Parker D; Barber, Patrick S; Kelley, Steven P; Rogers, Robin D

2014-05-01

109

High ionicity ionic liquids (HIILs): comparing the effect of ethylsulfonate and ethylsulfate anions.  

PubMed

The subject of ionicity has been extensively discussed in the last decade, due to the importance of understanding the thermodynamic and thermophysical behaviour of ionic liquids. In our previous work, we established that ionic liquids' ionicity could be improved by the dissolution of simple inorganic salts in their milieu. In this work, a comparison between the thermophysical properties of two binary systems of ionic liquid + inorganic salt is presented. The effect of the ammonium thiocyanate salt on the ionicity of two similar ionic liquids, 1-ethyl-3-methylimidazolium ethylsulfonate and ethylsulfate, is investigated in terms of the related thermophysical properties, such as density, viscosity and ionic conductivity in the temperature range 298.15-323.15 K. In addition, spectroscopic (NMR and Raman) and molecular dynamic studies were conducted in order to better understand the interactions that occur at a molecular level. The obtained results reveal that although the two anions of the ionic liquid exhibit similar chemical structures, the presence of one additional oxygen in the ethylsulfate anion has a major impact on the thermophysical properties of the studied systems. PMID:24061089

Oliveira, Filipe S; Pereiro, Ana B; Araújo, João M M; Bernardes, Carlos E S; Canongia Lopes, José N; Todorovic, Smilja; Feio, Gabriel; Almeida, Pedro L; Rebelo, Luís P N; Marrucho, Isabel M

2013-11-01

110

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

2013-09-01

111

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

112

Durable Electrooptic Devices Comprising Ionic Liquids  

DOEpatents

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

Burrell, Anthony K. (Los Alamos, NM); Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM)

2008-11-11

113

Durable electrooptic devices comprising ionic liquids  

DOEpatents

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM); Burrell, Anthony K. (Los Alamos, NM)

2006-10-10

114

Durable electrooptic devices comprising ionic liquids  

DOEpatents

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

Burrell, Anthony K. (Los Alamos, NM); Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM)

2009-12-15

115

Microwave-assisted synthesis using ionic liquids.  

PubMed

The research and application of green chemistry principles have led to the development of cleaner processes. In this sense, during the present century an ever-growing number of studies have been published describing the use of ionic liquids (ILs) as solvents, catalysts, or templates to develop more environmentally friendly and efficient chemical transformations for their use in both academia and industry. The conjugation of ILs and microwave irradiation as a non-conventional heating source has shown evident advantages when compared to conventional synthetic procedures for the generation of fast, efficient, and environmental friendly synthetic methodologies. This review focuses on the advances in the use of ILs in organic, polymers and materials syntheses under MW irradiation conditions. PMID:19507045

Martínez-Palou, Rafael

2010-02-01

116

Thermodynamic properties of ionic liquids-a cluster approach.  

PubMed

We describe a method for calculating thermodynamic properties of ionic liquids by using standard quantum statistical thermodynamics as characterized by ab initio techniques. We review briefly how thermochemical properties for different sized clusters of ionic liquids are calculated by standard ab initio programs. The cluster partition functions allow one to calculate energies, enthalpies and Gibbs energies. Assuming that the ionic liquid exists exclusively as isolated ion-pairs in the gaseous phase and regarding the largest clusters as possible liquid structures, we could estimate vapor pressures, enthalpies of vaporization and entropies of vaporization. For possible boiling points it is shown how they vary with pressure. PMID:18633554

Ludwig, Ralf

2008-08-01

117

Comparative study of bending characteristics of ionic polymer actuators containing ionic liquids for modeling actuation  

NASA Astrophysics Data System (ADS)

Ionic polymer metal composites (IPMCs) that can operate in air have recently been developed by incorporating an ionic liquid in ionic polymers. To understand transduction in these composites, it is important to determine the role of the ionic liquid in the ionic polymer (Nafion®), to identify the counter cation, and to investigate the interaction of IPMCs with water vapor in the air. We used Fourier-transform infrared spectroscopy to analyze three Nafion® membranes, which were soaked in mixtures of water and an ionic liquid (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIBF4), 1-buthyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4), and 1-buthyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6)). The results demonstrate that only cations (EMI+ and BMI+) in the ionic liquids are taken into the Nafion® membranes as counter ions and that the water content of the membranes in air is less than ~4% that of Nafion® swollen with water. Based on the experimental results, a transduction model is proposed for an IPMC with an ionic liquid. In this model, bending is caused by local swelling due to the volume effect of the bulky counter cations. This model can explain 30-50% of the experimentally observed bending curvature.

Kikuchi, Kunitomo; Sakamoto, Takumi; Tsuchitani, Shigeki; Asaka, Kinji

2011-04-01

118

Morita-Baylis-Hillman Reaction: ESI-MS(/MS) Investigation with Charge Tags and Ionic Liquid Effect Origin Revealed by DFT Calculations.  

PubMed

The use of a charge-tagged acrylate derivative bearing an imidazolium tag to study the Morita-Baylis-Hillman reaction via ESI-MS(/MS) monitoring and the effect of such tag (imidazolium cations and ion pairs) over TSs is described. The ionic nature of the substrate was meant to facilitate ESI transfer to the gas phase for direct mass spectrometric analysis. The detection and characterization of charged intermediates has suggested major reaction pathways. DFT calculations considering the effect of a polar and protic solvent (methanol), of a polar and aprotic solvent (acetonitrile), and of no solvent (gas phase) were used to predict possible TSs through a common accepted intermediate. The controversial proton transfer step, which may proceed via Aggarwal's or McQuade's proposals, was evaluated. Calculations predicted the formation of electrostatic intermediate complexes with both the cation and anion when charge-tagged reagents are used. These complexes contribute to the positive ionic liquid effect, and based on the formation of these unique complexes, a rationale for the ionic liquid effect is proposed. These complexes also pointed to a plausible explanation for the positive ionic liquid effect observed in several reactions that are difficult to be carried out in organic solvents but have shown a beneficial effect when performed in ionic liquids. PMID:24815995

Rodrigues, Thyago S; Silva, Valter H C; Lalli, Priscila M; de Oliveira, Heibbe C B; da Silva, Wender A; Coelho, Fernando; Eberlin, Marcos N; Neto, Brenno A D

2014-06-01

119

Low-pressure CO 2 sorption in ammonium-based poly(ionic liquid)s  

Microsoft Academic Search

Ammonium-based ionic liquid monomers and their corresponding polymers [poly(ionic liquid)s] are synthesized and characterized for CO2 sorption. The polymers have much higher CO2 sorption capacities than the room-temperature ionic liquids and imidazolium-based poly(ionic liquid)s. For example, P[VBTMA][PF6] with polystyrene backbone has a CO2 sorption capacity of 10.67mol%. The CO2 sorption is selective over N2 and O2. The effects of cation,

Jianbin Tang; Huadong Tang; Weilin Sun; Maciej Radosz; Youqing Shen

2005-01-01

120

Shear dynamics of nanoconfined ionic liquids.  

PubMed

We used molecular dynamics simulations to study the structure and shear dynamics of two ionic liquids (ILs) featuring the same cation 1-butyl-3-methyl-imidazolium or [BMIM], paired with bis(trifluoromethanesulphonyl)amide [NTF2] and tetrafluoroborate [BF4] anions, confined between two hydroxylated silica surfaces. The results demonstrate how the shape of IL molecules affects their layering structure at hydroxylated silica surfaces and how the layered structure of nanoconfined liquids determines their dynamical properties at the molecular level. When [BMIM][NTF2] is sheared, larger molecular fluctuations in the inner layers are required to stabilise the system, and the resulting dynamics is irregular. The alternating charged layers in [BMIM][BF4] allow the system to stabilise through smaller oscillations, and the layers appear to shear on top of each other in a laminar fashion. The simulated dynamics explains qualitatively the relative change in viscosity that the two ILs exhibit when confined, as has been observed in previous experiments. PMID:24562163

Canova, Filippo Federici; Matsubara, Hiroki; Mizukami, Masashi; Kurihara, Kazue; Shluger, Alexander L

2014-05-14

121

Particle aggregation mechanisms in ionic liquids.  

PubMed

Aggregation of sub-micron and nano-sized polystyrene latex particles was studied in room temperature ionic liquids (ILs) and in their water mixtures by time-resolved light scattering. The aggregation rates were found to vary with the IL-to-water molar ratio in a systematic way. At the water side, the aggregation rate is initially small, but increases rapidly with increasing IL content, and reaches a plateau value. This behaviour resembles simple salts, and can be rationalized by the competition of double-layer and van der Waals forces as surmised by the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). At the IL side, aggregation slows down again. Two generic mechanisms could be identified to be responsible for the stabilization in ILs, namely viscous stabilization and solvation stabilization. Viscous stabilization is important in highly viscous ILs, as it originates from the slowdown of the diffusion controlled aggregation due to the hindrance of the diffusion in a viscous liquid. The solvation stabilization mechanism is system specific, but can lead to a dramatic slowdown of the aggregation rate in ILs. This mechanism is related to repulsive solvation forces that are operational in ILs due to the layering of the ILs close to the surfaces. These two stabilization mechanisms are suspected to be generic, as they both occur in different ILs, and for particles differing in surface functionalities and size. PMID:24727976

Szilagyi, Istvan; Szabo, Tamas; Desert, Anthony; Trefalt, Gregor; Oncsik, Tamas; Borkovec, Michal

2014-04-23

122

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

123

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

124

Electropolymerization of polypyrrole by bipolar electrochemistry in an ionic liquid.  

PubMed

Bipolar electrochemistry has been recently explored for the modification of conducting micro- and nanoobjects with various surface layers. So far, it has been assumed that such processes should be carried out in low-conductivity electrolytes in order to be efficient. We report here the first bipolar electrochemistry experiment carried out in an ionic liquid, which by definition shows a relatively high conductivity. Pyrrole has been electropolymerized on a bipolar electrode, either in ionic liquid or in acetonitrile. The resulting polymer films were characterized by scanning electron microscopy and by contact profilometry. We demonstrate that the films obtained in an ionic liquid are thinner and smoother than the films synthesized in acetonitrile. Furthermore, a well-defined band of polypyrrole can be obtained in ionic liquid, in contrast to acetonitrile for which the polypyrrole film is present on the whole anodic part of the bipolar electrode. PMID:24605863

Kong, Shuwei; Fontaine, Olivier; Roche, Jérôme; Bouffier, Laurent; Kuhn, Alexander; Zigah, Dodzi

2014-03-25

125

Hydrolysis of cellulose in SO?H-functionalized ionic liquids.  

PubMed

Influence of acidity and structure of ionic liquids on microcrystalline cellulose (MCC) hydrolysis was investigated. MnCl?-containing ionic liquids (ILs) were efficient catalysts and achieved MCC conversion rates of 91.2% and selectivities for 5-hydroxymethyl furfural (HMF), furfural and levulinic acid (LA) of 45.7%, 26.2% and 10.5%, respectively. X-ray diffractometry indicated that catalytic hydrolysis of MCC in ionic liquids resulted in the changes to MCC crystallinity and transformation of cellulose I into cellulose II. SO?H-functionalized ionic liquids showed higher activities than non-functionalized ILs. The simplicity of the chemical transformation of cellulose provides a new approach for the use this polymer as raw material for renewable energy and chemical industries. PMID:21757338

Tao, Furong; Song, Huanling; Chou, Lingjun

2011-10-01

126

Robust and versatile ionic liquid microarrays achieved by microcontact printing  

NASA Astrophysics Data System (ADS)

Lab-on-a-chip and miniaturized systems have gained significant popularity motivated by marked differences in material performance at the micro-to-nano-scale realm. However, to fully exploit micro-to-nano-scale chemistry, solvent volatility and lack of reproducibility need to be overcome. Here, we combine the non-volatile and versatile nature of ionic liquids with microcontact printing in an attempt to establish a facile protocol for high throughput fabrication of open microreactors and microfluidics. The micropatterned ionic liquid droplets have been demonstrated as electrochemical cells and reactors for microfabrication of metals and charge transfer complexes, substrates for immobilization of proteins and as membrane-free high-performance amperometric gas sensor arrays. The results suggest that miniaturized ionic liquid systems can be used to solve the problems of solvent volatility and slow mass transport in viscous ionic liquids in lab-on-a-chip devices, thus providing a versatile platform for a diverse number of applications.

Gunawan, Christian A.; Ge, Mengchen; Zhao, Chuan

2014-04-01

127

Silica xerogels and aerogels synthesized with ionic liquids  

Microsoft Academic Search

The synthesis of silica gels with ionic liquids (IL) as either additives or co-solvents is described. The wet gels were either dried by supercritical CO2 or by evaporation to obtain aerogels or xerogels, respectively. The effects of two ionic liquids: 1-butyl-3-methyl imidazolium tetrafluororate (IL1) and 1-butyl-4-methyl pyridinium tetrafluoroborate (IL2), on the structural and textural characteristics of gels were investigated. IL2

Ali Karout; Alain. C. Pierre

2007-01-01

128

Preparation of Cellulose Nanocrystals Using an Ionic Liquid  

Microsoft Academic Search

In this paper cellulose nanocrystals were prepared by treating microcrystalline cellulose with 1-butyl-3-methylimidazolium\\u000a hydrogen sulphate ionic liquid. Cellulose nanocrystals, after separation from ionic liquid, were characterized by X-ray diffraction\\u000a (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM) Transmission Electron Microscope\\u000a (TEM) and Thermogravimetric analysis. XRD results showed no changes in type of cellulose after the treatment with

Zakaria Man; Nawshad Muhammad; Ariyanti Sarwono; Mohamad Azmi Bustam; M. Vignesh Kumar; Sikander Rafiq

129

Membrane contactor assisted extraction/reaction process employing ionic liquids  

DOEpatents

The present invention relates to a functionalized membrane contactor extraction/reaction system and method for extracting target species from multi-phase solutions utilizing ionic liquids. One preferred embodiment of the invented method and system relates to an extraction/reaction system wherein the ionic liquid extraction solutions act as both extraction solutions and reaction mediums, and allow simultaneous separation/reactions not possible with prior art technology.

Lin, Yupo J. (Naperville, IL); Snyder, Seth W. (Lincolnwood, IL)

2012-02-07

130

The Pressure–Viscosity Coefficient of Several Ionic Liquids  

Microsoft Academic Search

The choice of cation and anion in an ionic liquid (IL) as well as the design of ion side chains determine the fundamental\\u000a properties of ILs, which permits creating tailor-made lubricants and lubricant additives. So, the study of the influence\\u000a of molecular structure on thermophysical properties of ionic liquids is essential for their use in lubrication. Recent results\\u000a from the

A. S. Pensado; M. J. P. Comuñas; J. Fernández

2008-01-01

131

Stability of electrochemomechanical strains in polypyrrole films using ionic liquids  

Microsoft Academic Search

Electrochemomechanical strain (ECMS) of conducting polymers, polypyrrole (PPy) films was studied using several kinds of ionic liquids and the mixed solution with organic solvents from the view points of strain and stability. The PPy films, which were electrodeposited from lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), showed porous morphology. The ECMS in the films operated in ionic liquids was less than 5%, demonstrating a

Kentaro Yamato; Kazuo Tominaga; Wataru Takashima; Keiichi Kaneto

2009-01-01

132

Carbon–ionic liquid double-layer capacitors  

Microsoft Academic Search

A series of electrochemical capacitors, based on activated carbon powders (ACP, specific surface area 870 and 2600 m2\\/g) and ionic liquids as electrolytes, were prepared and tested. The ionic liquids consisted of 1-ethyl-3-methyl imidazolium (EMIm+), 1-butyl-3-methyl imidazolium (BMIm+) and 1-methyl-1-propyl pyrrolidinium (BMPy+) cations, as well as of tetrafluoroborate, hexafluorophosphate and bis((trifluoromethyl)sulfonyl) imide anions. A typical capacitor consisted of two electrodes

A. Lewandowski; M. Galinski

2004-01-01

133

Preparation and Application of Ionic Liquid-Modified Stationary Phases in High Performance Liquid Chromatography  

Microsoft Academic Search

Ionic liquid-modified stationary phases are an important class of stationary phase. They have been shown to have a capability of separating various classes of compounds in HPLC. In this review, we focus on the preparation and application of ionic liquid-modified stationary phases in HPLC. First, two common theories of retention mechanism in the ionic liquid-modified stationary phases in HPLC were

Wentao Bi; Jun Zhou; Kyung-Ho Row

2012-01-01

134

Preparation and Application of Ionic Liquid-Modified Stationary Phases in High Performance Liquid Chromatography  

Microsoft Academic Search

Ionic liquid-modified stationary phases are an important class of stationary phase. They have been shown a capability of separating various classes of compounds in HPLC. In this review, we focus on the preparation and application of ionic liquid-modified stationary phases in HPLC. First, two common theories of retention mechanism in the ionic liquid-modified stationary phases in HPLC were discussed. Then,

Jun Zhou; Wentao Bi; Kyung-Ho Row

2011-01-01

135

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

136

Ionic-liquid-like copolymer stabilized nanocatalysts in ionic liquids I. Platinum catalyzed selective hydrogenation of o-chloronitrobenzene  

Microsoft Academic Search

An ionic-liquid-like copolymer was used to stabilize the platinum nanoclusters in ionic liquids. Catalytic performance was tested by the selective hydrogenation of o-chloronitrobenzene. Platinum catalysts Pt-I (5.1 nm) and Pt-II (1.7 nm) both exhibited excellent activity and selectivity for the reaction and were recycled with the activity and selectivity preserved. An unprecedented total turnover number (>25,900) was obtained on the

Chao-xian Xiao; Han-zhi Wang; Xin-dong Mu; Yuan Kou

2007-01-01

137

In situ ionic-liquid-dispersive liquid-liquid microextraction of Sudan dyes from liquid samples.  

PubMed

In situ ionic-liquid-dispersive liquid-liquid microextraction was introduced for extracting Sudan dyes from different liquid samples followed by detection using ultrafast liquid chromatography. The extraction and metathesis reaction can be performed simultaneously, the extraction time was shortened notably and higher enrichment factors can be obtained compared with traditional dispersive liquid-liquid microextraction. When the extraction was coupled with ultrafast liquid chromatography, a green, convenient, cheap, and efficient method for the determination of Sudan dyes was developed. The effects of various experimental factors, including type of extraction solvent, amount of 1-hexyl-3-methylimidazolium chloride, ratio of ammonium hexafluorophosphate to 1-hexyl-3-methylimidazolium chloride, pH value, salt concentration in sample solution, extraction time and centrifugation time were investigated and optimized for the extraction of four kinds of Sudan dyes. The limits of detection for Sudan I, II, III, and IV were 0.324, 0.299, 0.390, and 0.655 ng/mL, respectively. Recoveries obtained by analyzing the seven spiked samples were between 65.95 and 112.82%. The consumption of organic solvent (120 ?L acetonitrile per sample) was very low, so it could be considered as a green analytical method. PMID:24840862

Xu, Bo; Song, Daqian; Wang, Yuanpeng; Gao, Yan; Cao, Bocheng; Zhang, Hanqi; Sun, Ying

2014-08-01

138

Ionic liquids screening for desulfurization of natural gasoline by liquid–liquid extraction  

Microsoft Academic Search

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization\\u000a of NG was performed by means of liquid–liquid extraction method at room temperature and atmospheric pressure. Experimental\\u000a ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally\\u000a and under microwave and sonochemical conditions. The effect

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

2010-01-01

139

LIQUID\\/LIQUID EXTRACTION OF METAL IONS IN ROOM TEMPERATURE IONIC LIQUIDS  

Microsoft Academic Search

The search for more environmentally-friendly reaction media has prompted the development of a wide array of alternative systems that will sustain biphasic separations with aqueous solutions without the use of volatile organic compounds (VOCs). We have begun to employ Room Temperature Ionic Liquids (RTIL), specifically 1-alkyl-3-methylimidazolium hexafluorophosphate ([Cnmim][PF6]), as VOC replacements in liquid\\/liquid separations of metal ions from aqueous solutions.

Ann E. Visser; Richard P. Swatloski; Scott T. Griffin; Deborah H. Hartman; Robin D. Rogers

2001-01-01

140

Liquid–liquid extraction of actinides, lanthanides, and fission products by use of ionic liquids: from discovery to understanding  

Microsoft Academic Search

Liquid–liquid extraction of actinides and lanthanides by use of ionic liquids is reviewed, considering, first, phenomenological\\u000a aspects, then looking more deeply at the various mechanisms. Future trends in this developing field are presented.

Isabelle Billard; Ali Ouadi; Clotilde Gaillard

2011-01-01

141

Ionic liquids based on aliphatic tetraalkylammonium dications and TFSI anion as potential electrolytes  

Microsoft Academic Search

A new series of ionic liquids containing aliphatic tetraalkylammonium dications with alkyl linkage chains and TFSI anion as potential electrolytes were prepared and characterized. Some of the important physicochemical and electrochemical properties of these prepared ionic liquids, including melting point, density, solubility in common solvents, ionic conductivity, thermal and electrochemical stability, were investigated. These ammonium dicationic ionic liquids exhibited five

Zhengxi Zhang; Li Yang; Shichun Luo; Miao Tian; Kazuhiro Tachibana; Kouichi Kamijima

2007-01-01

142

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

2012-04-21

143

Excess dielectron in an ionic liquid as a dynamic bipolaron.  

PubMed

We report an ab initio molecular dynamics simulation study on the accommodation of a dielectron in a pyridinium ionic liquid in both the singlet and triplet state. In contrast to water and liquid ammonia, a dielectron does not prefer to reside in cavity-shaped structures in the ionic liquid. Instead, it prefers to be distributed over more cations, with long-lived diffuse and short-lived localized distributions, and with a triplet ground state and a low-lying, open-shell singlet excited state. The two electrons evolve nonsynchronously in both states via a diffuse-versus-localized interconversion mechanism that features a dynamic bipolaron with a modest mobility, slightly lower than a hydrated electron. This work presents the first detailed study on the structures and dynamics of a dielectron in ionic liquids. PMID:23521297

Liu, Jinxiang; Wang, Zhiping; Zhang, Meng; Cukier, Robert I; Bu, Yuxiang

2013-03-01

144

Excess Dielectron in an Ionic Liquid as a Dynamic Bipolaron  

NASA Astrophysics Data System (ADS)

We report an ab initio molecular dynamics simulation study on the accommodation of a dielectron in a pyridinium ionic liquid in both the singlet and triplet state. In contrast to water and liquid ammonia, a dielectron does not prefer to reside in cavity-shaped structures in the ionic liquid. Instead, it prefers to be distributed over more cations, with long-lived diffuse and short-lived localized distributions, and with a triplet ground state and a low-lying, open-shell singlet excited state. The two electrons evolve nonsynchronously in both states via a diffuse-versus-localized interconversion mechanism that features a dynamic bipolaron with a modest mobility, slightly lower than a hydrated electron. This work presents the first detailed study on the structures and dynamics of a dielectron in ionic liquids.

Liu, Jinxiang; Wang, Zhiping; Zhang, Meng; Cukier, Robert I.; Bu, Yuxiang

2013-03-01

145

Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes  

Microsoft Academic Search

We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as

Wataru Ogihara; Jiazeng Sun; Maria Forsyth; Douglas R. MacFarlane; Masahiro Yoshizawa; Hiroyuki Ohno

2004-01-01

146

Ionic liquid clusters: structure, formation mechanism, and effect on the behavior of ionic liquids.  

PubMed

The microstructure of ionic liquids (ILs) has attracted much attention due to their relevance in physiochemical properties and behavior of ILs. The existence of clusters (or microheterogeneous structure) is one of the main features for many ILs, which provides fundamental information for understanding the performance of ILs in their applications. This perspective concentrates on the recent progresses in IL clusters research. Firstly, we give a brief introduction on the structure of clusters in neat ILs and IL solutions. Secondly, the possible formation mechanism of the IL clusters is described. Then, the effects of the clusters on the physicochemical properties, interfacial properties, confined geometry and assembly processes of ILs are discussed. Finally, we address the associated challenges and prospects on the future study of IL clusters. PMID:24263402

Chen, Shimou; Zhang, Suojiang; Liu, Xiaomin; Wang, Jinquan; Wang, Jianji; Dong, Kun; Sun, Jian; Xu, Baohua

2014-04-01

147

Electrochemical study of dialcarb "distillable" room-temperature ionic liquids.  

PubMed

Electrode-dependent potential windows (see picture, GC=glassy carbon) are determined for five dialkylammonium carbamate (dialcarb) room-temperature ionic liquids in a systematic study of their physical and electrochemical properties. The viscosity and conductivity of the dialcarb ionic liquids, which are "distillable" at low temperature, are comparable to those of some conventional room-temperature ionic liquids. The physical and electrochemical properties of five "distillable" room-temperature ionic liquids from the dialcarb family (dialkylammonium carbamates formed from CO(2) and dialkyl amines) are systematically investigated. In particular dimethyl (DIMCARB), diethyl (DIECARB), dipropyl (DIPCARB), methylethyl (MEETCARB), and methylpropyl (MEPRCARB) carbamate ionic liquids are studied. The temperature dependence of the viscosity and conductivity of MEETCARB exhibit an Arrhenius-type relationship. Except for DIPCARB, which has too high a resistance, a reference potential scale is available by using the IUPAC recommended redox system, that is the cobalticenium/cobaltocene (Cc(+)/Cc) process, which exhibits an ideal reversible voltammetric response. Oxidation of decamethylferrocene, but not ferrocene, also is ideal in DIMCARB, DIECARB, MEETCARB, and MEPRCARB. The magnitudes of the potential windows of the electrochemically viable dialcarbs are investigated and follow the order of glassy carbon>Au>Pt>Hg. Diffusion coefficients of Cc(+), DmFc, and double-layer capacitance values are compared in each dialcarb. Despite the considerable viscosity of the dialcarbs, steady-state voltammetric behavior is achieved at a rotating disk electrode for rotation rates of 1000 rpm or higher. PMID:19090511

Wang, Huan; Zhao, Chuan; Bhatt, Anand I; MacFarlane, Douglas R; Lu, Jia-Xing; Bond, Alan M

2009-02-01

148

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

149

Task-specific ionic liquid for solubilizing metal oxides.  

PubMed

Protonated betaine bis(trifluoromethylsulfonyl)imide is an ionic liquid with the ability to dissolve large quantities of metal oxides. This metal-solubilizing power is selective. Soluble are oxides of the trivalent rare earths, uranium(VI) oxide, zinc(II) oxide, cadmium(II) oxide, mercury(II) oxide, nickel(II) oxide, copper(II) oxide, palladium(II) oxide, lead(II) oxide, manganese(II) oxide, and silver(I) oxide. Insoluble or very poorly soluble are iron(III), manganese(IV), and cobalt oxides, as well as aluminum oxide and silicon dioxide. The metals can be stripped from the ionic liquid by treatment of the ionic liquid with an acidic aqueous solution. After transfer of the metal ions to the aqueous phase, the ionic liquid can be recycled for reuse. Betainium bis(trifluoromethylsulfonyl)imide forms one phase with water at high temperatures, whereas phase separation occurs below 55.5 degrees C (temperature switch behavior). The mixtures of the ionic liquid with water also show a pH-dependent phase behavior: two phases occur at low pH, whereas one phase is present under neutral or alkaline conditions. The structures, the energetics, and the charge distribution of the betaine cation and the bis(trifluoromethylsulfonyl)imide anion, as well as the cation-anion pairs, were studied by density functional theory calculations. PMID:17048916

Nockemann, Peter; Thijs, Ben; Pittois, Stijn; Thoen, Jan; Glorieux, Christ; Van Hecke, Kristof; Van Meervelt, Luc; Kirchner, Barbara; Binnemans, Koen

2006-10-26

150

Ionic conductivity of imidazole-functionalized liquid crystal mesogens  

NASA Astrophysics Data System (ADS)

Imidazole has been investigated as a novel anhydrous proton conducting functional group that could enable higher temperature operation (> 120 ^oC) of polymer electrolyte fuel cells. Its amphoteric behavior can support Grotthuss-like proton transport; however molecular mobility and a high concentration of imidazole groups are needed to achieve high ionic conductivity. Our hypothesis is that liquid crystal ordering, particularly in layered smectic phase, can facilitate formation of 2D proton transport and promote proton conductivity. We have designed and synthesized two imidazole-terminated liquid crystal mesogens, and the ionic conductivities in the liquid crystalline and isotropic states have been measured. Here we report on synthesis and characterization of diacylhydrazine liquid crystals bearing imidazole terminal groups. The proton conductivity of products is compared to pure liquid imidazole and to liquid crystal mesogens without imidazole groups.

Roddecha, Supacharee; Anthamatten, Mitchell

2012-02-01

151

Trace element partitioning between ionic crystal and liquid  

NASA Technical Reports Server (NTRS)

The partitioning of trace elements between ionic crystals and the melt has been correlated with lattice energy of the host. The solid-liquid partition coefficient has been expressed in terms of the difference in relative ionic radius of the trace element and the homogeneous and heterogeneous strain of the host lattice. Predictions based on this model appear to be in general agreement with data for alkali nitrates and for rare-earth elements in natural garnet phenocrysts.

Tsang, T.; Philpotts, J. A.; Yin, L.

1978-01-01

152

Molecular electrostatic properties of ions in an ionic liquid  

Microsoft Academic Search

We have analysed the electronic wave functions from an ab initio simulation of the ionic liquid (room temperature molten salt) dimethyl imidazolium chloride ([dmim][Cl] or [C1mim][Cl]) using localized Wannier orbitals. This allows us to assign electron density to individual ions. The probability distributions of the ionic dipole moments for an isolated ion and for ions in solution are compared. The

Carlos E. Resende Prado; Mario G. Del Pópolo; T. G. A. Youngs; Jorge Kohanoff; R. M. Lynden-Bell

2006-01-01

153

The use of supported acidic ionic liquids in organic synthesis.  

PubMed

Catalysts obtained by the immobilisation of acidic ionic liquids (ILs) on solid supports offer several advantages compared to the use of catalytically active ILs themselves. Immobilisation may result in an increase in the number of accessible active sites of the catalyst and a reduction of the amount of the IL required. The ionic liquid films on the carrier surfaces provide a homogeneous environment for catalytic reactions but the catalyst appears macroscopically as a dry solid, so it can simply be separated from the reaction mixture. As another advantage, it can easily be applied in a continuous fixed bed reactor. In the present review the main synthetic strategies towards the preparation of supported Lewis acidic and Brønsted acidic ILs are summarised. The most important characterisation methods and structural features of the supported ionic liquids are presented. Their efficiency in catalytic reactions is discussed with special emphasis on their recyclability. PMID:24972271

Skoda-Földes, Rita

2014-01-01

154

Energetic ionic liquids based on lanthanide nitrate complex anions.  

PubMed

Energetic ionic liquids based on anionic lanthanide nitrate complexes Cat(+) (3)[Ln(NO(3))(6)](3-), where Cat(+) is guanidinium, 4-aminotriazolium, 4-amino-1-methyltriazolium, 4-amino-1-ethyltriazolium, 4-amino-1-butyltriazolium, 1,5-diaminotetrazolium, and 1,5-diamino-4-methyltetrazolium, were prepared. The hexanitratolanthanate (-cerate) salts with the last two cations, which are the first CO-balanced energetic ionic liquids that are stable to hydrolysis and air, have impact sensitivities of about 27 J. These ionic liquids were obtained by an environmentally friendly, simple method using nitrate-containing precursors. All salts were fully characterized by IR and NMR spectroscopy, elemental analysis, and determination of thermal stability, phase behavior, density, and water content. According to theoretical calculations, these new compounds have potential as propellants. PMID:18973160

Tao, Guo-Hong; Huang, Yangen; Boatz, Jerry A; Shreeve, Jean'ne M

2008-01-01

155

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

156

Mechanical properties and XRD of Nafion modified by 2-hydroxyethylammonium ionic liquids  

NASA Astrophysics Data System (ADS)

In this work, the Nafion 112 membrane impregnated with 2-hydroxyethylammonium carboxylate ionic liquids have been investigated. The used ionic liquids were 2-hydroxyethylammonium formate [HEA]F, acetate [HEA]A and lactate [HEA]L. Prepared composite membranes Nafion/ionic liquid are characterized by mechanical testing, such as tensile test and creep test. It is found that ionic liquids decrease elastic modulus and creep compliance, but do not have significant effect on the tensile strength. Also, composite membranes were studied by wide angle X-ray diffraction. All ionic liquids shift the peak maximum to the lower angle. In this work, only biodegradable ionic liquids were used for composite preparation.

Garaev, V.; Pavlovica, S.; Reinholds, I.; Vaivars, G.

2013-12-01

157

Ionic liquids as solvents for polymerization processes—Progress and challenges  

Microsoft Academic Search

Ionic liquids (ILs) are organic salts that are liquid at ambient temperatures. Ionic liquids have emerged as a new class of solvents for practical applications due to their unique combination of low volatility, chemical stability, high conductivity, wide electrochemical window, ability to dissolve organic and inorganic solutes and gases, and tunable solvent properties. In polymer science ionic liquids are used

Przemys?aw Kubisa

2009-01-01

158

Adsorption separation processes for ionic liquid catalytic processes  

US Patent & Trademark Office Database

Presently disclosed are methods and apparatus for separation of reaction products from reaction mixtures in an ionic liquid catalysis process, particularly in conversion of biomass, cellulose, and sugars into chemical intermediates such as 5-hydroxymethylfurfural (HMF). In one embodiment an ion exclusion adsorption mechanism is used for the separation process. The process comprises (i) mixing the ionic liquid-containing reaction mixture with de-ionized water, (ii) flowing the water solution mixture into an adsorption column, (iii) eluting the column with a water- and/or alcohol-based fluid, and (iv) collecting separated fractions at different elution times.

2012-08-07

159

Direct observation of spiropyran phosphorescence in imidazolium ionic liquids  

NASA Astrophysics Data System (ADS)

Emission spectroscopy is used to investigate the photochromism of a spiropyran ester in imidazolium ionic liquids. While the spiropyran exhibits positive photochromism, the ring-opening reaction is slowed such that both fluorescence from the merocyanine form and phosphorescence from the spiro form are observed. These results illustrate the first example of spiropyran phosphorescence in ionic liquids and suggest that this system could be used to design a robust two-color emitting molecular device that depends on the state of the photochrome, where the state can be modulated by internal (the medium) and external (irradiation wavelength) factors.

Naughton, Sean P.; Gaudet, Robyn M.; Leslie, Anne A.; Keirstead, Amy E.

2013-01-01

160

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

161

Ionic liquids: the link to high-temperature molten salts?  

PubMed

Due to their wide thermal windows, ionic liquids can be regarded as the missing link between aqueous/organic solutions and high-temperature molten salts. They can be employed efficiently for the coating of other metals with thin layers of tantalum, aluminum, and presumably many others at reasonable temperatures by electrochemical means. The development of ionic liquids, especially air and water stable ones, has opened the door for the electrodeposition of reactive elements such as, for example, Al, Ta, and Si, which in the past were only accessible using high-temperature molten salts or, in part, organic solvents. PMID:17521159

El Abedin, Sherif Zein; Endres, Frank

2007-11-01

162

Preparation of microfibers from wood/ionic liquid solutions.  

PubMed

Two types of ionic liquids, 1-ethyl-3-methylimidazolim acetate and 1-ethyl-3-methylimidazolium lactate, were employed for the direct processing of pine wood into microfibers. The concentration of 5 wt.% of wood in ionic liquids was rated as the most appropriate for electrospinning. The fibers were electrospun into the collector water bath. The final structure varied from individual microfibers to fiber bundles. It was demonstrated that 1-ethyl-3-methylimidazolium lactate is a powerful solvent and provides the direct transformation of pristine pine wood into the non-wovens. PMID:23218285

Polaskova, Martina; Cermak, Roman; Verney, Vincent; Ponizil, Petr; Commereuc, Sophie; Gomes, Margarida F Costa; Padua, Agilio A H; Mokrejs, Pavel; Machovsky, Michal

2013-01-30

163

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

164

Transport of salicylic acid through supported liquid membrane based on ionic liquids  

Microsoft Academic Search

Transport of salicylic acid (SA) through flat-sheet supported liquid membrane (SLM) was investigated using as liquid membrane the ionic liquids 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim][PF6]) or ethylammonium nitrate (EAN). Using [C6mim][PF6], it has been observed that the transport efficiency decreases with increasing pH, indicating that the un-dissociated form of SA is mainly extracted. On the other hand, the ionic dissociated form of

Noura kouki; Rafik Tayeb; Ramzi Zarrougui; Mahmoud Dhahbi

2010-01-01

165

Development of new class of ion conductive polymers based on ionic liquids  

Microsoft Academic Search

A series of polymerizable ionic liquid was synthesized and polymerized to prepare new type polymer electrolytes. The effects of position of imidazolium cation, spacer structure and length, and anion species on the ionic conductivity have been investigated. Polycation-type ionic liquids having flexible long spacer showed the ionic conductivity of about 10?4Scm?1 at room temperature. Polyanion-type ionic liquids without spacer structure

Hiroyuki Ohno; Masahiro Yoshizawa; Wataru Ogihara

2004-01-01

166

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

2012-04-17

167

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

168

Comparative investigation on electrochemical behavior of hydroquinone at carbon ionic liquid electrode, ionic liquid modified carbon paste electrode and carbon paste electrode  

Microsoft Academic Search

Ionic liquid, 1-heptyl-3-methylimidazolium hexafluorophosphate (HMIMPF6), has been used to fabricate two new electrodes, carbon ionic liquid electrode (CILE) and ionic liquid modified carbon paste electrode (IL\\/CPE), using graphite powder mixed with HMIMPF6 or the mixture of HMIMPF6\\/paraffin liquid as the binder, respectively. The electrochemical behaviors of hydroquinone at the CILE, the IL\\/CPE and the CPE were investigated in phosphate buffer

Ya Zhang; Jian Bin Zheng

2007-01-01

169

Fabrication of fiber supported ionic liquids and methods of use  

DOEpatents

One or more embodiments relates to the production of a fabricated fiber having an asymmetric polymer network and having an immobilized liquid such as an ionic liquid within the pores of the polymer network. The process produces the fabricated fiber in a dry-wet spinning process using a homogenous dope solution, providing significant advantage over current fabrication methods for liquid-supporting polymers. The fabricated fibers may be effectively utilized for the separation of a chemical species from a mixture based on the selection of the polymer, the liquid, and the solvent utilized in the dope.

Luebke, David R; Wickramanayake, Shan

2013-02-26

170

QSPR and Artificial Neural Network Predictions of Hypergolic Ignition Delays for Energetic Ionic Liquids.  

National Technical Information Service (NTIS)

Due to their negligible volatility, energetic ionic liquids are being considered as next generation hypergolic fuels for replacing toxic monomethylhydrazine. One design challenge for energetic ionic liquids is to maintain their ignition delays as close to...

D. Sengupta G. L. Vaghjiani J. V. Cole M. Z. Pindera

2010-01-01

171

A Ionic Liquid-Channel Field Effect Transistor  

Microsoft Academic Search

A theoretical and experimental study was carried out on a new microfabricated device, an ionic liquid-channel field-effect transistor (ILCFET). The ILCFET resembles a metal-oxide-semiconductor field-effect transistor (MOSFET) except that the current flowing from the source to the drain is carried in thin channels by ions of a liquid electrolyte. Both have an electric field, transverse to the current flow, induced

Stephanie Anne Gajar

1992-01-01

172

Room-Temperature Ionic Liquids for Electrochemical Capacitors  

NASA Technical Reports Server (NTRS)

A document discusses room-temperature ionic liquids (RTILs) used as electrolytes in carbon-nanotube-based, electrochemical, double-layer capacitors. Unlike the previous electrolyte (EtNB4 in acetonitrile), the RTIL used here does not produce cyanide upon thermal decomposition and does not have a moisture sensitivity.

Fireman, Heather; Yowell, Leonard; Moloney, Padraig G.; Arepalli, Sivaram; Nikolaev, P.; Huffman, C.; Ready, Jud; Higgins, C.D.; Turano, S. P.; Kohl, P.A.; Kim, K.

2009-01-01

173

Lunar Oxygen Production and Metals Extraction Using Ionic Liquids  

NASA Technical Reports Server (NTRS)

Initial results indicate that ionic liquids are promising media for the extraction of oxygen from lunar regolith. IL acid systems can solubilize regolith and produce water with high efficiency. IL electrolytes are effective for water electrolysis, and the spent IL acid media are capable of regeneration.

Marone, Matthew; Paley, Mark Steven; Donovan, David N.; Karr, Laurel J.

2009-01-01

174

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...

175

High performance batteries with carbon nanomaterials and ionic liquids  

DOEpatents

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

176

Robust and versatile ionic liquid microarrays achieved by microcontact printing.  

PubMed

Lab-on-a-chip and miniaturized systems have gained significant popularity motivated by marked differences in material performance at the micro-to-nano-scale realm. However, to fully exploit micro-to-nano-scale chemistry, solvent volatility and lack of reproducibility need to be overcome. Here, we combine the non-volatile and versatile nature of ionic liquids with microcontact printing in an attempt to establish a facile protocol for high throughput fabrication of open microreactors and microfluidics. The micropatterned ionic liquid droplets have been demonstrated as electrochemical cells and reactors for microfabrication of metals and charge transfer complexes, substrates for immobilization of proteins and as membrane-free high-performance amperometric gas sensor arrays. The results suggest that miniaturized ionic liquid systems can be used to solve the problems of solvent volatility and slow mass transport in viscous ionic liquids in lab-on-a-chip devices, thus providing a versatile platform for a diverse number of applications. PMID:24781644

Gunawan, Christian A; Ge, Mengchen; Zhao, Chuan

2014-01-01

177

SOLVENT-FREE SONOCHEMICAL PREPARATION OF IONIC LIQUIDS  

EPA Science Inventory

An ultrasound-assisted preparation of a series of ambient temperature ionic liquids, 1-alkyl-3-methylimidazolium (AMIM) halides, that proceeds via efficient reaction of 1-methyl imidazole with alkyl halides/terminal dihalides under solvent-free conditions, is described. ...

178

Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids  

Microsoft Academic Search

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

R. G. Reddy

2007-01-01

179

Tunable Wavelength Soft Photoionization of Ionic Liquid Vapors (Preprint).  

National Technical Information Service (NTIS)

Combined data of photoelectron spectra and photoionization efficiency curves in the near threshold ionization region of isolated ion-pairs from emim Tf2N, emim Pf2N, and dmpim Tf2N, ionic liquid vapors reveal small shifts in the ionization energies of ion...

G. H. Miley M. P. Reilly

2009-01-01

180

Ionic Liquid Lubrication Effects on Ceramics in a Water Environment  

Microsoft Academic Search

Ionic liquids were studied to determine their effectiveness as boundary lubricant additives for water. The chemical and tribochemical reactions that govern their behavior were probed to understand lubrication mechanisms. Under water lubricated conditions, silicon nitride ceramics are characterized by a running-in period of high friction, during which time the surface is modified causing a dramatic decrease in friction and wear.

B. S. Phillips; J. S. Zabinski

2004-01-01

181

Physical Properties of Ionic Liquids: Database and Evaluation  

Microsoft Academic Search

A comprehensive database on physical properties of ionic liquids (ILs), which was collected from 109 kinds of literature sources in the period from 1984 through 2004, has been presented. There are 1680 pieces of data on the physical properties for 588 available ILs, from which 276 kinds of cations and 55 kinds of anions were extracted. In terms of the

Suojiang Zhang; Ning Sun; Xuezhong He; Xingmei Lu; Xiangping Zhang

2006-01-01

182

Ionic Liquids as Extraction Solvents: Where do We Stand?  

Microsoft Academic Search

The unique physicochemical properties of ionic liquids (ILs) and the relative ease with which these properties can be fine?tuned by altering the cationic or anionic moieties comprising the IL have led to intense interest in their use as alternatives to conventional organic solvents in a wide range of synthetic, catalytic, and electrochemical applications. Recent work by a number of investigators

Mark L. Dietz

2006-01-01

183

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

184

Study on hydroxylammonium-based ionic liquids. I. Characterization.  

PubMed

Two selected ammonium-based ionic liquids, 2-hydroxyethyltrimethylammonium L-(+)-lactate and tris(2-hydroxyethyl)methylammonium methylsulfate, were fully characterized. The most relevant thermophysical properties of pure fluids were measured and analyzed as a function of temperature. Structural features were inferred from solvatochromic and Fourier transform infrared (FTIR) studies. Moisture absorption ability was also studied by gravimetric, spectroscopic, and Karl Fischer methods. Likewise, the water effect on fluids properties was analyzed. Polarity was studied by approaches based on solvatochromic measurements and on the water effect on FTIR spectra. Moreover, as computational work, quantum chemistry and molecular dynamics simulation methods were used to analyze the main molecular-level structural features in these fluids. The work is divided into two parts; in this first paper, the main objective is fully characterizing these ionic liquids in the pure state, and in the second paper CO(2) absorption will be analyzed, therefore leading to a deep knowledge of factors controlling structuring, properties, and CO(2) absorption for this family of ionic liquids in comparison with available information for other relevant types of ionic liquids. PMID:21932776

Aparicio, Santiago; Atilhan, Mert; Khraisheh, Majeda; Alcalde, Rafael

2011-11-01

185

Microwave-assisted separation of ionic liquids from aqueous solution of ionic liquids.  

PubMed

Microwave-assisted separation has been applied to recover ionic liquid (IL) from its aqueous solution as an efficient method with respect to time and energy compared to the conventional vacuum distillation. Hydrophilic ILs such as 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([Bmim][TfO]) and 1-ethyl-3-methylimidazolium methylsulfate ([Emim][MS]) could be recovered in 6 min from the mixture of ILs and water (1:1, w/w) under microwave irradiation at constant power of 10 W while it took at least 240 min to obtain ILs containing same water content (less than 0.5 wt%) by conventional vacuum oven at 363.15 K with 90 kPa of vacuum pressure. Energy consumptions per gram of evaporated water from the homogeneous mixture of hydrophilic ILs and water (1:1, w/w) by microwave-assisted separation were at least 52 times more efficient than those in conventional vacuum oven. It demonstrated that microwave-assisted separation could be used for complete recovery of ILs in sense of time and energy as well as relevant purity. PMID:21040926

Ha, Sung Ho; Mai, Ngoc Lan; Koo, Yoon-Mo

2010-12-01

186

Physical and electrochemical properties of low-viscosity phosphonium ionic liquids as potential electrolytes  

Microsoft Academic Search

A new group of room temperature ionic liquids based on triethylalkylphosphonium cations together with a bis(trifluoromethylsulfonyl)imide anion as a novel electrolyte is presented in this report. It was found that phosphonium ionic liquids showed lower viscosities and higher conductivities than those of the corresponding ammonium ionic liquids. Particularly, phosphonium ionic liquids containing a methoxy group, triethyl(methoxymethyl)phosphonium bis(trifluoromethylsulfonyl)imide and triethyl(2-methoxyethyl)phosphonium bis(trifluoromethylsulfonyl)imide,

Katsuhiko Tsunashima; Masashi Sugiya

2007-01-01

187

Thermoelectric Potential of Polymer-Scaffolded Ionic Liquid Membranes  

NASA Astrophysics Data System (ADS)

Organic thin films have been viewed as potential thermoelectric (TE) materials, given their ease of fabrication, flexibility, cost effectiveness, and low thermal conductivity. However, their intrinsically low electrical conductivity is a main drawback which results in a relatively lower TE figure of merit for polymer-based TE materials than for inorganic materials. In this paper, a technique to enhance the ion transport properties of polymers through the introduction of ionic liquids is presented. The polymer is in the form of a nanofiber scaffold produced using the electrospinning technique. These fibers were then soaked in different ionic liquids based on substituted imidazolium such as 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium bromide. This method was applied to electrospun polyacrylonitrile and a mixture of polyvinyl alcohol and chitosan polymers. The ion transport properties of the membranes have been observed to increase with increasing concentration of ionic liquid, with maximum electrical conductivity of 1.20 × 10-1 S/cm measured at room temperature. Interestingly, the maximum electrical conductivity value surpassed the value of pure ionic liquids. These results indicate that it is possible to significantly improve the electrical conductivity of a polymer membrane through a simple and cost-effective method. This may in turn boost the TE figures of merit of polymer materials, which are well known to be considerably lower than those of inorganic materials. Results in terms of the Seebeck coefficient of the membranes are also presented in this paper to provide an overall representation of the TE potential of the polymer-scaffolded ionic liquid membranes.

Datta, R. S.; Said, S. M.; Sahamir, S. R.; Karim, M. R.; Sabri, M. F. M.; Nakajo, T.; Kubouchi, M.; Hayashi, K.; Miyazaki, Y.

2014-06-01

188

Electrolytic Conductivity of Four Imidazolium-Based Ionic Liquids  

NASA Astrophysics Data System (ADS)

In this article, electrolytic (ionic) conductivity measurements of four ionic liquids (ILs), namely, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([Cmim][NTf]), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Cmim][OTf]), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Cmim][NTf]), and 1-ethyl-3-methylimidazolium ethyl sulfate ([Cmim][EtSO]) (ECOENG212), were performed in a temperature range of (288.15 to 333.15) K. [Cmim][NTf] was chosen to be a reference ionic liquid for several properties, including the electrolytic conductivity by the IUPAC Project 2002-005-1-100. For that reason, the measurements performed with that ionic liquid primarily serve the purpose to validate the instrumentation and the experimental procedure used in this work. The measurements were carried out using a complex impedance method, applying a novel electronic device designed and constructed for this purpose. The complete setup includes a Schott Instruments LF 913 T, used as a four-electrode conductivity cell, and a lock-in amplifier. The cell was calibrated using standard reference KCl aqueous solutions. The measurements of the impedance of the conductivity cell were carried out along a range of frequencies from (0.2 to 30) kHz, and the results were extrapolated to infinite frequency, in order to determine the electrolytic conductivity of the liquid samples. The results obtained for the ionic liquid [Cmim][NTf] were compared to reference data, and it was estimated that the overall uncertainty of the present results is better than 2 %. All the data obtained were compared with available literature data, and were analyzed and discussed in respect to the effect of temperature, cation alkyl chain length, and anion.

Calado, Marta S.; Diogo, João C. F.; Correia da Mata, José L.; Caetano, Fernando J. P.; Visak, Zoran P.; Fareleira, João M. N. A.

2013-07-01

189

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

190

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...

191

Low-viscosity and low-melting point asymmetric trialkylsulfonium based ionic liquids as potential electrolytes  

Microsoft Academic Search

Nine new ionic liquids based on small asymmetric trialkylsulfonium cations with TFSI? anion were prepared and characterized. Physical and electrochemical properties of these ionic liquids, including melting point, thermal stability, viscosity, conductivity and electrochemical window were determined. Reducing symmetry of cations reduces the melting points of these ILs. Some of these hydrophobic ionic liquids showed low-viscosity and low-melting point characteristics.

Shaohua Fang; Li Yang; Chao Wei; Chengxin Peng; Kazuhiro Tachibana; Kouichi Kamijima

2007-01-01

192

Vaporisation and thermal decomposition of dialkylimidazolium halide ion ionic liquids.  

PubMed

Vaporisation and liquid phase thermal decomposition, TD, of two halide ion ionic liquids, 1-octyl-3-methylimidazolium chloride, [C8C1Im]Cl, and 1-octyl-3-methylimidazolium iodide, [C8C1Im]I, are investigated using temperature programmed desorption (TPD) line of sight mass spectrometry (LOSMS) at ultra-high vacuum (UHV). The ability to use MS to distinguish between vaporisation and TD allows the thermodynamics/kinetics of both vaporisation and TD to be investigated within the same experiments. Vaporisation of both halide ion ionic liquids is demonstrated. For both [C8C1Im]Cl and [C8C1Im]I the vapour is shown to be composed of neutral ion pairs (NIPs). The enthalpy of vaporisation at temperature T, ?vapHT, was experimentally determined as ?vapH455 = 151 ± 10 kJ mol(-1) for [C8C1Im]Cl and ?vapH480 = 149 ± 8 kJ mol(-1) for [C8C1Im]I. Extrapolation of ?vapHT to the reference temperature, 298 K, gave ?vapH298 = 166 ± 10 kJ mol(-1) for [C8C1Im]Cl and ?vapH298 = 167 ± 8 kJ mol(-1) for [C8C1Im]I, higher than most ?vapH298 values measured to date for other [C8C1Im](+)-containing ionic liquids. In addition, predictions of ?vapH298 for other halide ion ionic liquids are made. Liquid phase TD is shown to proceed via nucleophilic substitution to give two sets of products: 1-octylimidazole and methylhalide, and 1-methylimidazole and 1-octylhalide. The activation energy of TD at a temperature T, Ea,TD,T, is measured for the nucleophilic substitution of [C8C1Im]I to give methyliodide; Ea,TD,480 = 136 ± 15 kJ mol(-1). Ea,TD,T is measured for the nucleophilic substitution of [C8C1Im]Cl to give methylchloride; Ea,TD,455 = 132 ± 10 kJ mol(-1). The fact that ?vapHT and Ea,TD,T are the same (within error) for both ionic liquids is commented upon, and conclusions are drawn as to the thermal stability of these ionic liquids. PMID:24105256

Lovelock, Kevin R J; Armstrong, James P; Licence, Peter; Jones, Robert G

2014-01-28

193

Force microscopy of layering and friction in an ionic liquid.  

PubMed

The mechanical properties of the ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py1,4][FAP]) in confinement between a SiOx and a Au(1?1?1) surface are investigated by means of atomic force microscopy (AFM) under electrochemical control. Up to 12 layers of ion pairs can be detected through force measurements while approaching the tip of the AFM to the surface. The particular shape of the force versus distance curve is explained by a model for the interaction between tip, gold surface and ionic liquid, which assumes an exponentially decaying oscillatory force originating from bulk liquid density correlations. Jumps in the tip-sample distance upon approach correspond to jumps of the compliant force sensor between branches of the oscillatory force curve. Frictional force between the laterally moving tip and the surface is detected only after partial penetration of the last double layer between tip and surface. PMID:24919549

Hoth, Judith; Hausen, Florian; Müser, Martin H; Bennewitz, Roland

2014-07-16

194

Force microscopy of layering and friction in an ionic liquid  

NASA Astrophysics Data System (ADS)

The mechanical properties of the ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py1,4][FAP]) in confinement between a SiOx and a Au(1?1?1) surface are investigated by means of atomic force microscopy (AFM) under electrochemical control. Up to 12 layers of ion pairs can be detected through force measurements while approaching the tip of the AFM to the surface. The particular shape of the force versus distance curve is explained by a model for the interaction between tip, gold surface and ionic liquid, which assumes an exponentially decaying oscillatory force originating from bulk liquid density correlations. Jumps in the tip–sample distance upon approach correspond to jumps of the compliant force sensor between branches of the oscillatory force curve. Frictional force between the laterally moving tip and the surface is detected only after partial penetration of the last double layer between tip and surface.

Hoth, Judith; Hausen, Florian; Müser, Martin H.; Bennewitz, Roland

2014-07-01

195

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

196

Decoupling of ionic conductivity from structural dynamics in polymerized ionic liquids.  

PubMed

Charge transport and structural dynamics in low molecular weight and polymerized 1-vinyl-3-pentylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) are investigated by a combination of broadband dielectric spectroscopy, dynamic mechanical spectroscopy and differential scanning calorimetry. While the dc conductivity and fluidity exhibit practically identical temperature dependence for the non-polymerized IL, a significant decoupling of ionic conduction from structural dynamics is observed for the polymerized IL. In addition, the dc conductivity of the polymerized IL exceeds that of its molecular counterpart by four orders of magnitude at their respective calorimetric glass transition temperatures. This is attributed to the unusually high mobility of the anions especially at lower temperatures when the structural dynamics is significantly slowed down. A simple physical explanation of the possible origin of the remarkable decoupling of ionic conductivity from structural dynamics is proposed. PMID:24718358

Sangoro, J R; Iacob, C; Agapov, A L; Wang, Y; Berdzinski, S; Rexhausen, H; Strehmel, V; Friedrich, C; Sokolov, A P; Kremer, F

2014-05-28

197

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

198

Bulk and liquid-vapor interface of pyrrolidinium-based ionic liquids: a molecular simulation study.  

PubMed

Using molecular dynamics simulations, we have studied the structure of three 1-butyl-1-methylpyrrolidinium ionic liquids whose anions are triflate, bis(trifluoromethanesulfonyl)imide, and tris(pentafluoroethyl)trifluorophosphate. The structure of the bulk phase of the three ionic liquids has been interpreted using radial and spatial distribution functions and structure factors that allows us to characterize the morphology of the polar and nonpolar domains present in this family of liquids. The size of the polar regions depends on the anion size, whereas the morphology of the nonpolar domains is anion-independent. Furthermore, the surface ordering properties of the ionic liquids and charge and density profiles were also studied using molecular simulations. The surface tension of the liquid-vapor interfaces of these ionic liquids was also predicted from our molecular simulations. In addition, microscopic structural analysis of orientational ordering at the interface and density profiles along the direction normal to the interface suggest that the alkyl chains of the cation tend to protrude toward the vacuum, and the presence of the interface leads to a strong organization of the liquid phase in the region close to the interface. In the interfacial area, the polar regions of the ionic liquids are more structured than those in the bulk phase, whereas the opposite behavior is observed for the nonpolar regions. PMID:24383956

Paredes, Xavier; Fernández, Josefa; Pádua, Agílio A H; Malfreyt, Patrice; Malberg, Friedrich; Kirchner, Barbara; Pensado, Alfonso S

2014-01-23

199

Can Ionic Liquids Be Used As Templating Agents For Controlled Design of Uranium-Containing Nanomaterials?  

SciTech Connect

Nanostructured uranium oxides have been prepared in ionic liquids as templating agents. Using the ionic liquids as reaction media for inorganic nanomaterials takes advantage of the pre-organized structure of the ionic liquids which in turn controls the morphology of the inorganic nanomaterials. Variation of ionic liquid cation structure was investigated to determine the impact on the uranium oxide morphologies. For two ionic liquid cations, increasing the alkyl chain length increases the aspect ratio of the resulting nanostructured oxides. Understanding the resulting metal oxide morphologies could enhance fuel stability and design.

Visser, A.; Bridges, N.; Tosten, M.

2013-04-09

200

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

201

Reduction of Metal Oxide to Metal using Ionic Liquids  

SciTech Connect

A novel pathway for the high efficiency production of metal from metal oxide means of electrolysis in ionic liquids at low temperature was investigated. The main emphasis was to eliminate the use of carbon and high temperature application in the reduction of metal oxides to metals. The emphasis of this research was to produce metals such as Zn, and Pb that are normally produced by the application of very high temperatures. The reduction of zinc oxide to zinc and lead oxide to lead were investigated. This study involved three steps in accomplishing the final goal of reduction of metal oxide to metal using ionic liquids: 1) Dissolution of metal oxide in an ionic liquid, 2) Determination of reduction potential using cyclic voltammetry (CV) and 3) Reduction of the dissolved metal oxide. Ionic liquids provide additional advantage by offering a wide potential range for the deposition. In each and every step of the process, more than one process variable has been examined. Experimental results for electrochemical extraction of Zn from ZnO and Pb from PbO using eutectic mixtures of Urea ((NH2)2CO) and Choline chloride (HOC2H4N(CH3)3+Cl-) or (ChCl) in a molar ratio 2:1, varying voltage and temperatures were carried out. Fourier Transform Infra-Red (FTIR) spectroscopy studies of ionic liquids with and without metal oxide additions were conducted. FTIR and induction coupled plasma spectroscopy (ICPS) was used in the characterization of the metal oxide dissolved ionic liquid. Electrochemical experiments were conducted using EG&G potentiostat/galvanostat with three electrode cell systems. Cyclic voltammetry was used in the determination of reduction potentials for the deposition of metals. Chronoamperometric experiments were carried out in the potential range of -0.6V to -1.9V for lead and -1.4V to -1.9V for zinc. The deposits were characterized using XRD and SEM-EDS for phase, morphological and elemental analysis. The results showed that pure metal was deposited on the cathode. Successful extraction of metal from metal oxide dissolved in Urea/ChCl (2:1) was accomplished. The current efficiencies were relatively high in both the metal deposition processes with current efficiency greater than 86% for lead and 95% for zinc. This technology will advance the metal oxide reduction process by increasing the process efficiency and also eliminate the production of CO2 which makes this an environmentally benign technology for metal extraction.

Dr. Ramana Reddy

2012-04-12

202

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

203

Quasi-Solid State Dye-sensitized Solar Cells Based on Polyvinylpyrrolidone With Ionic Liquid  

Microsoft Academic Search

A new ionic liquid polymer gel electrolyte containing 1-butyl-3-methylimidazolium iodide, polyvinylpyrrolidone, potassium iodide, and iodine has been prepared and characterized. Controlling the concentration of 1-butyl-3-methylimidazolium iodide, KI, and I2 with 0.9 M, 0.5 M, and 0.12 M, respectively, the ionic liquid polymer gel electrolyte attains the maximum ionic conductivity (at 30°C) of 2.3 mS cm. Based on the ionic liquid

L. Fan; S. Kang; J. Wu; S. Hao; Z. Lan; J. Lin

2010-01-01

204

Dissolution and depolymerization of barley starch in selected ionic liquids.  

PubMed

Polysaccharides like starch are poorly soluble in common solvents. However, certain ionic liquids (ILs) have been found to dissolve them, although some depolymerization happens during the dissolution. Dissolution and depolymerization of barley starch in ten ionic liquids have been studied with p-TsOH as a catalyst under controlled microwave heating. Dissolution time and the extent of the depolymerization of starch, determined by using HPLC-ELSD, were specific to each IL. Dialkylimidazolium halide ILs dissolved starch fast and depolymerized it substantially producing 79-100% water-soluble starch oligomers with the average molecular weight of 1000-2000Da. 1-Ethyl-3-methylimidazolium phosphate ([EMIM][Me2PO4]) and 2-hydroxyethylammonium formate ([NH3CH2CH2OH][HCOO]) dissolved starch slowly and depolymerized it least among the tested ILs. For the slow depolymerization of starch these ILs can be considered as suitable solvents for starch modifications where its depolymerization should be avoided. PMID:23465905

Lappalainen, Katja; Kärkkäinen, Johanna; Lajunen, Marja

2013-03-01

205

Hydroxynitrile lyase catalysis in ionic liquid-containing systems.  

PubMed

The cleavage of mandelonitrile catalysed by hydroxynitrile lyases (HNL) from Prunus amygdalus (PaHNL) and Manihot esculenta (MeHNL) proceeded more rapidly in monophasic aqueous media containing 1-propyl-3-methylimidazolium tetrafluoroborate [C4MIm][BF4] than in media containing acetonitrile or THF. Both HNLs were much more thermostable in [C4MIm][BF4] than in acetonitrile or THF. The addition of each of the four ionic liquids 1-butyl-, 1-pentyl- and 1-hexyl-3-methylimidazolium tetrafluoroborates at 2-6% (v/v in the aqueous phase) increased both the enzyme activity and the product e.e. in the PaHNL-catalysed transcyanation in an aqueous/DIPE biphasic system. However, MeHNL was inactivated by the ionic liquids, as indicated by the decreased reaction rate, substrate conversion and product e.e. PMID:16215854

Lou, Wen-Yong; Xu, Ruo; Zong, Min-Hua

2005-09-01

206

Hydrolysis of polycarbonate catalyzed by ionic liquid [Bmim][Ac].  

PubMed

Hydrolysis of polycarbonate (PC) was studied using ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) as a catalyst. The influences of temperature, time, water dosage and [Bmim][Ac] dosage on the hydrolysis reaction were examined. Under the conditions of temperature 140°C, reaction time 3.0 h, m([Bmim][Ac]):m(PC)=1.5:1 and m(H(2)O):m(PC)=0.35:1, the conversion of PC was nearly 100% and the yield of bisphenol A (BPA) was over 96%. The ionic liquid could be reused up to 6 times without apparent decrease in the conversion of PC and yield of BPA. The kinetics of the reaction was also investigated. The results showed that the hydrolysis of PC in [Bmim][Ac] was a first-order kinetic reaction with an activation energy of 228 kJ/mol. PMID:23246956

Song, Xiuyan; Liu, Fusheng; Li, Lei; Yang, Xuequn; Yu, Shitao; Ge, Xiaoping

2013-01-15

207

Carbon films produced from ionic liquid carbon precursors  

DOEpatents

The invention is directed to a method for producing a film of porous carbon, the method comprising carbonizing a film of an ionic liquid, wherein the ionic liquid has the general formula (X.sup.+a).sub.x(Y.sup.-b).sub.y, wherein the variables a and b are, independently, non-zero integers, and the subscript variables x and y are, independently, non-zero integers, such that ax=by, and at least one of X.sup.+ and Y.sup.- possesses at least one carbon-nitrogen unsaturated bond. The invention is also directed to a composition comprising a porous carbon film possessing a nitrogen content of at least 10 atom %.

Dai, Sheng; Luo, Huimin; Lee, Je Seung

2013-11-05

208

Ionic liquids for separation of olefin-paraffin mixtures  

DOEpatents

The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula ##STR00001## wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group --N--SO.sub.2--(CF.sub.2).sub.nCF.sub.3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.

Dai, Sheng; Luo, Huimin; Huang, Jing-Fang

2013-09-17

209

Electrochemical capacitors with polymer electrolytes based on ionic liquids  

Microsoft Academic Search

A series of electrochemical capacitors, based on carbon powders (specific surface area 830 and 2600 m2\\/g) as an electroactive material, applying polymer–ionic liquid (IL) solid electrolytes were prepared and tested. Both polymer electrolytes as well as capacitor electrodes, in the form of thin foils, were prepared by a casting technique. All-plastic capacitors, having a coin-like shape, a diameter of 18

A Lewandowski; A ?widerska

2003-01-01

210

Ultrasound-assisted dissolution of cellulose in ionic liquid  

Microsoft Academic Search

Ultrasound-assisted dissolution of cellulose was performed in ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl). The dissolution process was monitored with polarizing microscope. The effects of parameters including ultrasonic power and irradiation time on cellulose dissolution time were investigated. The dissolution time required for complete dissolution decreased from 190min without assistance to 60min irradiated with 30W ultrasound for 20min. The regenerated cellulose samples

Wu Lan; Chuan-Fu Liu; Feng-Xia Yue; Run-Cang Sun; John F. Kennedy

2011-01-01

211

Succinoylation of cellulose catalyzed with iodine in ionic liquid  

Microsoft Academic Search

In present study, succinoylation of sugarcane bagasse cellulose was performed with succinic anhydride (SA) using iodine as a catalyst in solvent system containing ionic liquid (IL), 1-butyl-3-methylimidazolium chloride ([C4mim]Cl), and dimethylsulfoxide (DMSO). The results showed that all succinylated cellulosic derivatives had the degree of substitution (DS) in the range of 0.56–1.54, which noticeably increased compared with the products without any

C. F. Liu; A. P. Zhang; W. Y. Li; F. X. Yue; R. C. Sun

2010-01-01

212

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

213

Organic electrical double layer transistors gated with ionic liquids  

Microsoft Academic Search

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

Wei Xie; C. Daniel Frisbie

2011-01-01

214

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

215

Mixed ionic liquid as electrolyte for lithium batteries  

Microsoft Academic Search

Ionic liquids like 1-butyl-3-methylimidazolium tetrafluoroborate (IMIBF4) or hexafluorophosphate (IMIPF6) and 1-butyl-4-methylpyridinium tetrafluoroborate (PyBF4) were mixed with organic solvents such as butyrolactone (BL) and acetonitrile (ACN). A lithium salt (LiBF4 or LiPF6) was added to these mixtures for possible application in the field of energy storage (batteries or supercapacitors). Viscosities, conductivities and electrochemical windows at a Pt electrode of these electrolytes

M. Diaw; A. Chagnes; B. Carré; P. Willmann; D. Lemordant

2005-01-01

216

Lithium-metal potential in Li + containing ionic liquids  

Microsoft Academic Search

Impedance spectroscopy studies of the interface between lithium and ionic liquid (IL) showed the formation of a film (solid\\u000a electrolyte interface, SEI), protecting metal from its further dissolution. Consequently, the potential of metallic lithium\\u000a immersed in an electrolyte containing Li+ cations may be described as a Li|SEI|Li+ system, rather than simply Li\\/Li+. The potential of lithium-metal in a series of

Andrzej Lewandowski; Agnieszka Swiderska-Mocek

2010-01-01

217

Ionic liquid-based electrolytes for capacitor applications  

Microsoft Academic Search

In this work we have synthesized several novel ionic liquids (ILs) based on imidazolium\\/pyrrolidinium cations and maleate\\/phthalate anions. The 1.5mol\\/L solutions of the ILs in gamma-butyrolactone (GBL) solvent were prepared as the electrolytes of electrochemical energy storage devices such as electrochemical capacitors and electrolytic capacitors. The conductivity, electrochemical stability, sparking voltage and thermal stability of these electrolytes have been investigated

Qing Zhu; Ye Song; Xufei Zhu; Xinlong Wang

2007-01-01

218

Studies on the nuances of the electrochemically induced room temperature isomerization of cis-stilbene in acetonitrile and ionic liquids.  

PubMed

Electrochemical reduction of cis-stilbene occurs by two well-resolved one-electron reduction steps in acetonitrile with (n-Bu)4NPF6 as the supporting electrolyte and in N-butyl-N-methylpyrrolidinium (Pyrr1,4(+)) and (trimethylamine)(dimethylethylamine)-dihydroborate bis(trifluoromethylsulfonyl)amide (NTf2(-)) ionic liquids (ILs). Mechanistic details of the electroreduction have been probed by dc and Fourier transformed ac voltammetry, simulation of the voltammetry, bulk electrolysis, and EPR spectroscopy. The first one-electron reduction induces fast cis to trans isomerization in CH3CN and ILs, most likely occurring via disproportionation of cis-stilbene radical anions and fast transformation of the cis-dianion to the trans-configuration. The second reduction process is chemically irreversible in CH3CN due to protonation of the dianion but chemically reversible in highly aprotic ILs under high cis-stilbene concentration conditions. Increase of the (n-Bu)4NPF6 supporting electrolyte concentration (0.01-1.0 M) in CH3CN induces substantial positive shifts in the potentials for reduction of cis-stilbene, consistent with strong ion pairing of the anion radical and dianion with (n-Bu)4N(+). However, protection by ion pairing against protonation of the stilbene dianions or electrochemically induced cis-trans-stilbene isomerization is not achieved. Differences in electrode kinetics and reversible potentials for cis-stilbene(0/•-) and trans-stilbene(0/•-) processes are less pronounced in the Pyrr1,4-NTf2 ionic liquid than in the molecular solvent acetonitrile. PMID:24558952

Abdul-Rahim, Omar; Simonov, Alexandr N; Boas, John F; Rüther, Thomas; Collins, David J; Perlmutter, Patrick; Bond, Alan M

2014-03-20

219

A roadmap to uranium ionic liquids: anti-crystal engineering.  

PubMed

In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C4 mim) cation. As dithiocarbamate ligands binding to the UO2 (2+) unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure-property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. These materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery. PMID:24737451

Yaprak, Damla; Spielberg, Eike T; Bäcker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja-Verena

2014-05-19

220

The solvation structures of cellulose microfibrils in ionic liquids.  

PubMed

The use of ionic liquids for non-derivatized cellulose dissolution promises an alternative method for the thermochemical pretreatment of biomass that may be more efficient and environmentally acceptable than more conventional techniques in aqueous solution. Here, we performed equilibrium MD simulations of a cellulose microfibril in the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and compared the solute structure and the solute-solvent interactions at the interface with those from corresponding simulations in water. The results indicate a higher occurrence of solvent-exposed orientations of cellulose surface hydroxymethyl groups in BmimCl than in water. Moreover, spatial and radial distribution functions indicate that hydrophilic surfaces are a preferred site of interaction between cellulose and the ionic liquid. In particular, hydroxymethyl groups on the hydrophilic fiber surface adopt a different conformation from their counterparts oriented towards the fiber's core. Furthermore, the glucose units with these solvent-oriented hydroxymethyls are surrounded by the heterocyclic organic cation in a preferred parallel orientation, suggesting a direct and distinct interaction scheme between cellulose and BmimCl. PMID:22179764

Mostofian, Barmak; Smith, Jeremy C; Cheng, Xiaolin

2011-12-01

221

Charge ordering and intermediate range order in ammonium ionic liquids  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations were performed for ionic liquids based on the bis(trifluoromethylsulfonyl)imide anion, [NTf2], and ammonium cations with increasing length of the alkyl chain and ether functionalized chain. The signature of charge ordering is a sharp peak in the charge-charge structure factor, Sqq(k), whose intensity is barely affected for longer carbon chain in tetraalkylammonium systems, but decreases in ether functionalized ionic liquids. The first sharp diffraction peak (FSDP) and the corresponding intermediate range order (IRO) are observed in the total S(k) of ionic liquids containing ammonium cations with relatively long chains. The intensity of the FSDP is lower in the total S(k) of the ether derivative in comparison with the tetraalkylammonium counterpart of the same chain length. It is shown that the nature of the IRO is structural heterogeneity of polar and non-polar domains, even though domains defined by chain interactions in the ether derivatives become more polar. Charge correlation in the ether derivative is modified because cations can be coordinated by oxygen atoms of the ether functionalized chain of neighboring cations.

Siqueira, Leonardo J. A.; Ribeiro, Mauro C. C.

2011-11-01

222

Electrochemistry of sulfur and polysulfides in ionic liquids.  

PubMed

The electrochemistry of elemental sulfur (S(8)) and the polysulfides Na(2)S(4) and Na(2)S(6) has been studied for the first time in nonchloroaluminate ionic liquids. The cyclic voltammetry of S(8) in the ionic liquids is different to the behavior reported in some organic solvents, with two reductions and one oxidation peak observed. Supported by in situ UV-vis spectro-electrochemical experiments, the main reduction products of S(8) in [C(4)mim][DCA] ([C(4)mim] = 1-butyl-3-methylimidazolium; DCA = dicyanamide) have been identified as S(6)(2-) and S(4)(2-), and plausible pathways for the formation of these species are proposed. Dissociation and/or disproportionation of the polyanions S(6)(2-) and S(4)(2-) appears to be slow in the ionic liquid, with only small amounts of the blue radical species S(3)(•-) formed in the solutions at r.t., in contrast with that observed in most molecular solvents. PMID:21992687

Manan, Ninie S A; Aldous, Leigh; Alias, Yatimah; Murray, Paul; Yellowlees, Lesley J; Lagunas, M Cristina; Hardacre, Christopher

2011-12-01

223

Straightforward Synthesis of the Brønsted Acid hfipOSO3 H and its Application for the Synthesis of Protic Ionic Liquids.  

PubMed

The easily accessible hexafluoroisopropoxysulfuric acid (1, hfipOSO3 H; hfip=C(H)(CF3 )2 ) was synthesized by the reaction of hexafluoroisopropanol and chlorosulfonic acid on the kilogram scale and isolated in 98?% yield. The calculated gas-phase acidity (GA) value of 1 is 58?kJ?mol(-1) lower in ?G° than that of sulfuric acid (GA value determined by a CCSD(T)-MP2 compound method). Considering the gas-phase dissociation constant as a measure for the intrinsic molecular acid strength, a hfipOSO3 H molecule is more than ten orders of magnitude more acidic than a H2 SO4 molecule. The acid is a liquid at room temperature, distillable at reduced pressure, stable for more than one year in a closed vessel, reactive towards common solvents, and decomposes above 180?°C. It is a versatile compound for further applications, such as the synthesis of ammonium- and imidazolium-based air- and moisture-stable protic ionic liquids (pILs). Among the six synthesized ionic compounds, five are pILs with melting points below 100?°C and three of them are liquids at nearly room temperature. The conductivities and viscosities of two representative ILs were investigated in terms of Walden plots, and the pILs were found to be little associated ILs, comparable to conventional aprotic ILs. PMID:24862292

Beichel, Witali; Panzer, Johann M U; Hätty, Julian; Ye, Xiaowei; Himmel, Daniel; Krossing, Ingo

2014-06-23

224

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

225

Ordered and Disordered Polymerized Ionic Liquid Block Copolymers: Morphology and Ionic Conductivity  

NASA Astrophysics Data System (ADS)

We systematically studied the influence of temperature and relative humidity on morphology and ionic conductivity in polymerized ionic liquid block copolymers (PIL BCP). Poly(methyl methacrylate-b-1-[2-(methacryloyloxy)ethyl]-3-butylimidazolium-X^-) block copolymers (X^- = OH^-, Br^-) were characterized by SAXS, dynamical mechanical analysis, and electrochemical impedance spectroscopy. At 25 ^^oC, weak microphase separation was observed for the PIL BCP with ?PIL = 0.38 and X^- = OH^-. Upon increasing the relative humidity to 90%, this polymer exhibited an order-disorder transition (ODT). The ODT was further studied in the PIL BCPs with X^- = OH^- and 0.11 ?PIL 0.38 over a range of temperatures and %RH. In contrast, the PIL BCP with ?PIL = 0.38 and X^- = Br^- formed strongly microphase separated lamellae at all investigated T and %RH. At elevated temperature and 90 %RH, ionic conductivities of 30 and 6 mS/cm were observed for ?PIL = 0.38 and X^- = OH^- and Br^-, respectively, surpassing the conductivities of the corresponding PIL homopolymer. By selecting the counterion and relative humidity, we significantly impact the morphology and ionic conductivity of these PIL block copolymers.

Wang, Sharon; Ye, Yuesheng; Elabd, Yossef; Winey, Karen

2013-03-01

226

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

227

Optimization of cation structure of imidazolium-based ionic liquids as ionic solvents for rechargeable magnesium batteries  

Microsoft Academic Search

A series of imidazolium cation-based ionic liquids (ILs) have been synthesized and examined as ionic solvents for rechargeable magnesium batteries. The electrolyte solutions consist of these ILs dissolving methylmagnesium bromide with tetrahydrofuran (MeMgBr\\/THF). The chemical structure of imidazolium cation much influenced the ionic conductivity and the electrochemical window of the system. A reversible process of cathodic deposition and anodic dissolution

Takeshi Kakibe; Nobuko Yoshimoto; Minato Egashira; Masayuki Morita

2010-01-01

228

Separation of carbon dioxide from nitrogen or methane by supported ionic liquid membranes (SILMs): influence of the cation charge of the ionic liquid.  

PubMed

Supported ionic liquid membranes (SILMs) are promising tools for the separation of carbon dioxide from other gases. In this paper, new imidazolium, pyrrolidinium, piperidinium, and morpholinium ionic liquids with a triethylene glycol side chain and tosylate anions, as well as their symmetrical dicationic analogues, have been synthesized and incorporated into SILMs. The selectivities for CO2/N2 and CO2/CH4 separations have been measured. The selectivities exhibited by the dicationic ionic liquids are up to two times higher than the values of the corresponding monocationic ionic liquids. Quantum chemical calculations have been used to investigate the difference in the interaction of carbon dioxide with monocationic and dicationic ionic liquids. The reason for the increased gas separation selectivity of the dicationic ionic liquids is two-fold: (1) a decrease in permeance of nitrogen and methane through the ionic liquid layer, presumably due to their less favorable interactions with the gases, while the permeance of carbon dioxide is reduced much less; (2) an increase in the number of interaction sites for the interactions with the quadrupolar carbon dioxide molecules in the dicationic ionic liquids, compared to the monocationic analogues. PMID:24199938

Hojniak, Sandra D; Khan, Asim Laeeq; Hollóczki, Oldamur; Kirchner, Barbara; Vankelecom, Ivo F J; Dehaen, Wim; Binnemans, Koen

2013-12-01

229

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

2010-11-01

230

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

2013-01-01

231

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

PubMed Central

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.

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

2013-01-01

232

Pertraction of lactic acid through supported liquid membranes containing phosphonium ionic liquid  

Microsoft Academic Search

Pertraction of lactic acid (LA) through supported liquid membranes (SLM) was investigated in a spiral channel flat sheet module using a liquid membrane with ionic liquid tetradecyl(trihexyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (IL-104) which is an effective extractant of LA. The increase in IL-104 concentration in n-dodecane from 0.32 to 0.72kmolm?3 did not result in an increase of the overall mass-transfer coefficient of LA,

Ján Marták; Štefan Schlosser; Silvia Vl?ková

2008-01-01

233

Fluorescence response of coumarin-153 in N-alkyl-N-methylmorpholinium ionic liquids: are these media more structured than the imidazolium ionic liquids?  

PubMed

The fluorescence behavior of coumarin-153 (C153) has been studied in four N-alkyl-N-methylmorpholinium ionic liquids differing in the alkyl chain length attached to the N-methylmorpholinium cation as a function of the excitation wavelength and temperature to understand some of the physicochemical characteristics of these largely unexplored ionic liquids. While the polarity of the ionic liquid with the smallest alkyl chain length is found comparable to that of the commonly used imidazolium ionic liquids, the probe molecule experiences a less polar environment with increasing chain length of the alkyl group attached to the morpholinium cation. The room temperature steady-state fluorescence spectrum of C153 in these solvents is found to be dependent on the excitation wavelength, and this effect is most pronounced in long chain containing ionic liquids. A bathochromic shift of the fluorescence maximum is observed at higher temperature. The excitation wavelength and temperature dependence of the fluorescence of C153 is explained considering a domain structure of these ionic liquids. The time-resolved fluorescence anisotropy measurements indicate the microviscosity around the probe molecule to be significantly different from the bulk viscosity of the long-chain ionic liquids. The solvent reorganization dynamics, as studied by monitoring the time-dependent fluorescence Stokes shift of C153 in these ionic liquids, is found to be slow and similar to that in imidazolium ionic liquids. The time-resolved measurements under isoviscous conditions seem to provide additional support to the organized domain structure of these ionic liquids. PMID:23083398

Khara, Dinesh Chandra; Samanta, Anunay

2012-11-15

234

Application of Ionic Liquids in High Performance Reversed-Phase Chromatography  

PubMed Central

Ionic liquids, considered “green” chemicals, are widely used in many areas of analytical chemistry due to their unique properties. Recently, ionic liquids have been used as a kind of novel additive in separation and combined with silica to synthesize new stationary phase as separation media. This review will focus on the properties and mechanisms of ionic liquids and their potential applications as mobile phase modifier and surface-bonded stationary phase in reversed-phase high performance liquid chromatography (RP-HPLC). Ionic liquids demonstrate advantages and potential in chromatographic field.

Wang, Ye; Tian, Minglei; Bi, Wentao; Row, Kyung Ho

2009-01-01

235

Graphene/Ionic liquid composite films and ion exchange.  

PubMed

Wettability of graphene is adjusted by the formation of various ionic surfaces combining ionic liquid (IL) self-assembly with ion exchange. The functionalized ILs were designed and synthesized with the goal of obtaining adjustable wettability. The wettability of the graphene surface bearing various anions was measured systematically. The effect of solvent systems on ion exchange ratios on the graphene surface has also been investigated. Meanwhile, the mechanical properties of the graphene/IL composite films were investigated on a nanometer scale. The elasticity and adhesion behavior of the thin film was determined with respected to the indentation deformation by colloid probe nanoindentation method. The results indicate that anions played an important role in determining graphene/IL composite film properties. In addition, surface wetting and mechanics can be quantitatively determined according to the counter-anions on the surface. This study might suggest an alternate way for quantity detection of surface ions by surface force. PMID:24970602

Mo, Yufei; Wan, Yunfang; Chau, Alicia; Huang, Fuchuan

2014-01-01

236

Graphene/Ionic Liquid Composite Films and Ion Exchange  

PubMed Central

Wettability of graphene is adjusted by the formation of various ionic surfaces combining ionic liquid (IL) self-assembly with ion exchange. The functionalized ILs were designed and synthesized with the goal of obtaining adjustable wettability. The wettability of the graphene surface bearing various anions was measured systematically. The effect of solvent systems on ion exchange ratios on the graphene surface has also been investigated. Meanwhile, the mechanical properties of the graphene/IL composite films were investigated on a nanometer scale. The elasticity and adhesion behavior of the thin film was determined with respected to the indentation deformation by colloid probe nanoindentation method. The results indicate that anions played an important role in determining graphene/IL composite film properties. In addition, surface wetting and mechanics can be quantitatively determined according to the counter-anions on the surface. This study might suggest an alternate way for quantity detection of surface ions by surface force.

Mo, Yufei; Wan, Yunfang; Chau, Alicia; Huang, Fuchuan

2014-01-01

237

Ordering of Triblock Copolymer Surfactants by Blending with a Room Temperature Ionic Liquid  

NASA Astrophysics Data System (ADS)

Well-ordered block copolymer microdomains were obtained by blending Pluronic PEO-PPO-PEO triblock copolymer surfactants with the room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate. The selective association of the ionic liquid with the PEO blocks increases the segregation strength by increasing the effective interaction parameter between the blocks. The neat copolymer is phase-mixed in the melt whereas the addition of ionic liquid to the copolymer results in phase segregation, forming well-ordered microdomains. The ionic liquid was confirmed to interact with the PEO blocks by a depression in the melting point of the blends with increasing ionic liquid concentration. Further, small angle x-ray scattering experiments show a decrease in the breadth of the first order peak, as well as the appearance of higher order peaks, with increasing ionic liquid concentration. These results confirm the formation of well-ordered microdomains.

Miranda, Daniel; Watkins, James; Russell, Thomas

2009-03-01

238

Molecular dynamics simulations of charged nanoparticle self-assembly at ionic liquid-water and ionic liquid-oil interfaces  

NASA Astrophysics Data System (ADS)

Nanoparticle self-assembly at liquid-liquid interfaces can be significantly affected by the individual nanoparticle charges. This is particularly true at ionic liquid (IL) based interfaces, where Coulombic forces play a major role. Employing 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) as a model IL, we have studied the self-assembly of hydrophobic nanoparticles with different surface charges at the IL/water and IL/oil (hexane) interfaces using molecular dynamics simulations. In the IL/water system, the nanoparticles were initially dispersed in the water phase but quickly equilibrated at the interface, somewhat in favor of the IL phase. This preference was lessened with increased nanoparticle charge. In the IL/hexane system, all charged nanoparticles interacted with the IL to some extent, whereas the uncharged nanoparticles remained primarily in the hexane phase. Potential of mean force calculations supported the observations from the equilibrium studies and provided new insights into the interactions of the nanoparticles and ionic liquid based interfaces.

Frost, Denzil S.; Dai, Lenore L.

2012-02-01

239

[Study on mechanism of ionic liquid for methane plasma conversion using spectra method].  

PubMed

C6MIMBF4, C6MIMCF3 COO and C6MIMHSO4 were introduced into a direct current discharge plasma system respectively for methane conversion. The kinds of active species and relative intensity of spectral peaks were detected via online spectrum diagnosis technique of optical emission spectroscopy. Mechanism of ionic liquid for methane conversion in gas-liquid plasma was investigated. The results showed that a spatially and temporally stable gas-liquid interface was obtained in ionic liquid incorporated plasma system. With introduction of ionic liquid, methane conversion and C2 hydrocarbons yields increased. The C2 hydrocarbon selectivity greatly increased when C6MIMCF3 COO and C6MIMBF4 were introduced to the plasma, and decreased when C6MIMHSO4 was used. Active species like C, C2, C3, CH and H were detected in gas-liquid plasma system of methane discharge. Compared with the absence of ionic liquid in the plasma system, the relative intensity of spectral peaks of most active species increased when ionic liquid was introduced into the plasma system. 1H NMR results showed that the structure of ionic liquid kept stable during plasma discharge progress. Those indicated that ionic liquid could improve the plasma discharge intensity. At the same time, ionic liquid showed good catalytic activity in gas-liquid surface reaction. PMID:23387147

Zhang, Xiu-Ling; Zhou, Qian; Di, Lan-Bo; Yu, Miao

2012-11-01

240

Development of Ionic Liquid Monopropellants for In-Space Propulsion  

NASA Technical Reports Server (NTRS)

A family of new, low toxicity, high energy monopropellants is currently being evaluated at NASA Marshall Space Flight Center for in-space rocket engine applications such as reaction control engines. These ionic liquid monopropellants, developed in recent years by the Air Force Research Laboratory, could offer system simplification, less in-flight thermal management, and reduced handling precautions, while increasing propellant energy density as compared to traditional storable in-space propellants such as hydrazine and nitrogen tetroxide. However, challenges exist in identifying ignition schemes for these ionic liquid monopropellants, which are known to burn at much hotter combustion temperatures compared to traditional monopropellants such as hydrazine. The high temperature combustion of these new monopropellants make the use of typical ignition catalyst beds prohibitive since the catalyst cannot withstand the elevated temperatures. Current research efforts are focused on monopropellant ignition and burn rate characterization, parameters that are important in the fundamental understanding of the monopropellant behavior and the eventual design of a thruster. Laboratory studies will be conducted using alternative ignition techniques such as laser-induced spark ignition and hot wire ignition. Ignition delay, defined as the time between the introduction of the ignition source and the first sign of light emission from a developing flame kernel, will be measured using Schlieren visualization. An optically-accessible liquid monopropellant burner will be used to determine propellant burn rate as a function of pressure and initial propellant temperature. The burn rate will be measured via high speed imaging through the chamber s windows.

Blevins, John A.; Osborne, Robin; Drake, Gregory W.

2005-01-01

241

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

242

POSS based ionic liquid as an electrolyte for hybrid electrochromic devices  

Microsoft Academic Search

The main objective of this study was to broaden the assortment of I?\\/I3? redox ionic liquids using polyhedral oligomeric silsesquioxanes (POSS) acting as nanobuilding blocks for the construction of functionalized 1,3-alkylimidazolium iodide solid (melting temperature 150–200°C) and room temperature (RT) ionic liquids.The structural characteristics of the synthesised final ionic liquids and the corresponding intermediates were determined using 1H, 29Si NMR

M. ?olovi?; I. Jerman; M. Gaberš?ek; B. Orel

2011-01-01

243

Synthesis and Characterization of Thiazolium-Based Room Temperature Ionic Liquids for Gas Separations  

SciTech Connect

A series of novel thiazolium-bis(triflamide) based ionic liquids has been synthesized and characterized. Physicochemical properties of the ionic liquids such as thermal stability, phase transitions, and infrared spectra were analysed and compared to the imidazolium-based congeners. Several unique classes of ancillary substitutions are examined with respect to impacts on overall structure, in addition to their carbon dioxide absorption properties in supported ionic-liquid membranes for gas separation.

Hillesheim, Patrick C [ORNL; Mahurin, Shannon Mark [ORNL; Fulvio, Pasquale F [ORNL; Yeary, Joshua S [ORNL; Oyola, Yatsandra [ORNL; Jiang, Deen [ORNL; Dai, Sheng [ORNL

2012-01-01

244

Effect and mechanism of additives for ionic liquids as new lubricants  

Microsoft Academic Search

Ionic liquids are unique compounds, which exhibit low viscosity, non-flammability, low vapor pressure, and extremely high thermal stability. Therefore, they are expected as candidates for advanced lubricants. Several ionic liquids, derived from cations such as imidazolium, pridinium, ammonium, and anions such as BF4-, bis(trifluoromethylsulfonyl)imide (TFSI-) were examined under boundary conditions. It was found that tribological properties of ionic liquids are

Hideto Kamimura; Tomoo Kubo; Ichiro Minami; Shigeyuki Mori

2007-01-01

245

Ionic liquid mediated magnesium ion conduction in poly(ethylene oxide) based polymer electrolyte  

Microsoft Academic Search

Magnesium ion conduction in poly(ethylene oxide) (PEO) based polymer electrolyte incorporated with room temperature ionic liquid (RTIL) is reported. The electrolyte films comprise the PEO complexed with magnesium trifluoromethanesulfonate (or magnesium triflate) added with different amount of ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf). The polymer electrolyte with ?50wt.% of ionic liquid offers a maximum electrical conductivity of ?5.6×10?4Scm?1 at room temperature

Yogesh Kumar; S. A. Hashmi; G. P. Pandey

2011-01-01

246

Electronic functions of solid-to-liquid interfaces of organic semiconductor crystals and ionic liquid  

NASA Astrophysics Data System (ADS)

The environment of surface electrons at 'solid-to-liquid' interfaces is somewhat extreme, subjected to intense local electric fields or harsh chemical pressures that high-density ionic charge or polarization of mobile molecules create. In this proceedings, we argue functions of electronic carriers generated at the surface of organic semiconductor crystals in response to the local electric fields in the very vicinity of the interface to ionic liquid. The ionic liquids (ILs), or room temperature molten salts, are gaining considerable interest in the recent decade at the prospect of nonvolatile 'green solvents', with the development of chemically stable and nontoxic compounds. Moreover, such materials are also applied to electrolytes for lithium ion batteries and electric double-layer (EDL) capacitors. Our present solid-to-liquid interfaces of rubrene single crystals and ionic liquids work as fast-switching organic field-effect transistors (OFETs) with the highest transconductance, i.e. the most efficient response of the output current to the input voltage, among the OFETs ever built.

Takeya, J.

2008-10-01

247

Block Copolymer Micelle Shuttles between Water and Ionic Liquids  

NASA Astrophysics Data System (ADS)

The micelle shuttle is an interesting phenomenon recently discovered by our group: a reversible and intact migration of poly(butadiene- b-ethylene oxide) (PB-PEO) block copolymer micelles between water and a hydrophobic ionic liquid upon a simple temperature stimulus. The micelles allow for encapsulation of cargo molecules and the transfer enables control of their partitioning in the biphasic system. This simple round-trip delivery system can be used in delivery, reaction, and separations in synthesis and biphasic catalysis using ionic liquids. This thesis is aimed to systematically study the components, features, mechanism and possible applications of the micelle shuttle. For study on the components, several block copolymers and ionic liquids were employed to demonstrate the micelle shuttle, indicating the generality of the phenomenon. To control the loading and release of the micelle nanocarriers in the biphasic system, a thermoreversible micellization-transfer-demicellization shuttle was developed using a multiply thermosensitive block copolymer. The micelle shuttle was also demonstrated using micelles with different nanostructures, including spheres, cylinders, and vesicles. In particular, a new class of vesicles with ionic liquid interiors dispersed in water was developed using a vesicle shuttle. Permeability studies reflect the reasonably permeable membrane of the vesicles, which is desirable for potential applications of these responsive and stable vesicles as recyclable nanoreactors. As for research into the features, reversible and quantitative transfer appeared to be a common characteristic of the micelle shuttle. A strong temperature dependence of the micelle distribution in the biphasic system was observed, which is favorable for controlled delivery using the micelle shuttle. The transfer temperature determining the micelle partitioning in the biphasic system could be effectively tuned by simply using additives in the aqueous phase. To understand the transfer mechanism, the driving force, thermodynamics and kinetics of the micelle shuttle were investigated in detail utilizing shuttles of PEO homopolymers and dye-loaded PB-PEO micelles. A detailed multiple-step transfer mechanism was then proposed. To demonstrate possible applications, micelles formed by the commercial and inexpensive Pluronic block copolymer were employed as nanocarriers for delivery and extraction in the biphasic system. The vesicle shuttle was also utilized to transport various dyes in the biphasic system.

Bai, Zhifeng

248

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

2012-05-30

249

The role of ionic liquids in hydrogen storage.  

PubMed

Ionic liquid (IL) based H2 storage for H2 generation from NH3 BH3 derivatives is shown. These systems promote H2 generation at low temperature, with good reaction rates and high total H2 yields. The effects of ILs and the H2 yield in correlation with the basicity, the cations of the ILs, and the role of carbenes are discussed. Furthermore, mechanistic findings on the dehydrogenation are described. IL material blends are competitive with conventional H2 storage materials with experimental efficiencies of at least 6.5?wt?% H2 . PMID:24954029

Sahler, Sebastian; Sturm, Sebastian; Kessler, Michael T; Prechtl, Martin H G

2014-07-14

250

Electrodeposition of chalcopyrite films from ionic liquid electrolytes  

Microsoft Academic Search

An air and water stable room-temperature ionic liquid based on choline chloride\\/urea eutectic mixture has been investigated as a system for the electrodeposition of CuInSe2 (CIS) and Cu(In,Ga)Se2 (CIGS) films for photovoltaic applications. Deposition potentials and bath compositions were optimized to obtain Cu–In, Cu–In–Se and Cu–In–Ga–Se precursor films, which were selenized in a tube furnace at 500 °C for 30 min to

D. D. Shivagan; P. J. Dale; A. P. Samantilleke; L. M. Peter

2007-01-01

251

CO?-responsive microemulsions based on reactive ionic liquids.  

PubMed

We demonstrate that the nanodomains within a ternary system consisting of oil, surfactant, and a new reactive ionic liquid can be tuned reversibly upon exposure to and removal of CO2 under mild conditions of temperature and pressure. The equilibrium microstructures of these domains have been characterized by small-angle neutron scattering and demonstrate that control over emulsion morphology (and therefore physicochemical properties such as viscosity) and the breaking of emulsions can be achieved without the need for irreversible changes in system composition or significant energy input. PMID:24690009

Brown, Paul; Wasbrough, Matthew J; Gurkan, Burcu E; Hatton, T Alan

2014-04-22

252

Synthesis and properties of trigeminal tricationic ionic liquids.  

PubMed

Novel trigeminal tricationic ionic liquids (TTILs) have been successfully synthesized in high yields by means of Menschutkin quaternization via an S(N)1 mechanism. This reaction presents a new convenient method for transforming glycerol into multifunctional compounds. The physical properties of a series of TTILs were characterized by using a variety of techniques. The prepared salts were tested for antimicrobial activity. Electrochemical characterization of TTILs was also performed, which allowed the estimation of the conductivity of these new compounds, to establish their electrochemical stability window and capacitance properties over a wide range of temperatures. A good correlation of the physical properties of TTILs with capacitance values was observed. PMID:17212367

Pernak, Juliusz; Skrzypczak, Andrzej; Lota, Grzegorz; Frackowiak, Elzbieta

2007-01-01

253

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

254

Additive-containing ionic liquid electrolytes for secondary lithium battery  

Microsoft Academic Search

Room temperature ionic liquid (RTIL) consisting of N-methyl-N-propylpiperidinium (PP13) cation and bis(trifluoromethanesulfonyl)imide (TFSI) anion was synthesized and its electrochemical stability was investigated in comparison with 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6). The electrochemical window of PP13-TFSI (5.8V versus Li\\/Li+) is wider than that of BMIBF4 (4.7V) and BMIPF6 (4.5V). The cathodic limit of the PP13-TFSI is about ?0.3V versus

Jinqiang Xu; Jun Yang; Yanna NuLi; Jiulin Wang; Zongshuang Zhang

2006-01-01

255

Room-temperature phosphonium ionic liquids for supercapacitor application  

NASA Astrophysics Data System (ADS)

Ionic liquids (ILs) have been used as electrolytes for supercapacitors. Two phosphonium salts such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide (IL1) and trihexyl(tetradecyl) phosphonium dicyanamide (IL2) have been selected for this target. To decrease the viscosity of ILs, a small amount of acetonitrile (from 5 to 25 wt %) was added. Supercapacitor based on activated carbon (AC) as electrodes and IL1 with 25 wt % of acetonitrile supplied capacitance values of 100 F/g at a high operating voltage of 3.4 V. Such a supercapacitor reached a high energy of ~40 Wh/kg and a good cyclability.

Frackowiak, Elzbieta; Lota, Grzegorz; Pernak, Juliusz

2005-04-01

256

Analysis of mono- and oligosaccharides in ionic liquid containing matrices.  

PubMed

Ionic liquids (ILs), that is, salts with melting points <100°C, have recently attracted a lot of attention in biomass processing due to their ability to dissolve lignocellulosics. In this work, we studied how two imidazolium-based, hydrophilic, cellulose dissolving ionic liquids 1,3-dimethylimidazolium dimethylphosphate [DMIM]DMP and 1-ethyl-3-methylimidazolium acetate [EMIM]AcO affect the usually employed analytical methods for mono- and oligosaccharides, typical products from hydrolytic treatments of biomass. HPLC methods were severely hampered by the presence of ILs with loss of separation power and severe baseline problems, making their use for saccharide quantification extremely challenging. Problems in DNS photometric assay and chromatography were also encountered at high ionic liquid concentrations and many capillary electrophoresis (CE) methods did not allow an efficient analysis of saccharides in these matrices. In this paper we describe an optimized CE method with pre-column derivatization for the qualitative and quantitative analysis of mono- and oligosaccharides in sample matrices containing moderate (20-40% (v/v)) concentrations of ILs. The IL content and type in the sample matrix was found to affect both peak shape and quantification parameters. Generally, the presence of high IL concentrations (?20% (v/v)) had a dampening effect on the detection of the analytes. IL in lower concentrations of <20% (v/v) was, however, found to improve peak shape and/or separation in some cases. The optimized CE method has good sensitivity in moderate concentrations of the ionic liquids used, with limits of detection of 5mg/L for cellooligomers up to the size of cellotetraose and 5-20mg/L for cellopentaose and cellohexaose, depending on the matrix. The method was used for analysing the action of a commercial ?-glucosidase in ILs and for analysing saccharides in the IL containing hydrolysates from the hydrolysis of microcrystalline cellulose with Trichoderma reesei endoglucanase Cel5A. According to the results, [DMIM]DMP and [EMIM]AcO] showed clear differences in enzyme inactivation. PMID:23583452

Wahlström, Ronny; Rovio, Stella; Suurnäkki, Anna

2013-05-24

257

A routine synthesis of magnetite applied in ionic liquids  

NASA Astrophysics Data System (ADS)

This paper describe the synthesis of magnetite nanoparticles using 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF[. Iron (II) chloride and iron (III) chloride which dissolves in [BMIM][BF[ are coprecipitated in the presence of potassium hydroxide yielding magnetite. The stabilization of magnetite was realized without further purification with glycolic acid. The TEM images show spherical nanoparticles with mean diameter of 8nm. FTIR spectra contain the specific bands of both magnetite and glycolic acid indicating the formation of the magnetic nanoparticles stabilized with glycolic acid. Our results show that ionic liquids can be used as solvent to achieve magnetite stabilized by glycolic acid which shows superparamagnetic behaviour.

Nan, Alexandrina; Turcu, Rodica; Liebscher, Jürgen

2013-11-01

258

Methods of using ionic liquids having a fluoride anion as solvents  

DOEpatents

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 an ionic liquid having an acetate or formate anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of less than about 90.degree. C. during the contacting.

Pagoria, Philip (Livermore, CA); Maiti, Amitesh (San Ramon, CA); Gash, Alexander (Brentwood, CA); Han, Thomas Yong (Pleasanton, CA); Orme, Christine (Oakland, CA); Fried, Laurence (Livermore, CA)

2011-12-06

259

Use of salt hydrate pairs to control water activity for enzyme catalysis in ionic liquids.  

PubMed

Salt hydrate pairs were used to control water activity in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. It was shown that salt hydrate pairs behave essentially the same in ionic liquids as they do in organic solvents as long as they do not dissolve. Initial rate-water activity profiles were prepared for the immobilized Candida antarctica lipase catalyzed synthesis of 2-ethylhexyl methacrylate. The ability to use salt hydrate pairs for the control of water activity in ionic liquids should allow for improved comparison of enzyme activity and specificity in ionic liquids and conventional solvents. PMID:12790674

Berberich, Jason A; Kaar, Joel L; Russell, Alan J

2003-01-01

260

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

261

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

2008-11-01

262

Effective viscosities in thin ionic micellar liquid films  

SciTech Connect

Thin liquid films stabilized by surfactants above the critical micelle concentration exhibit stratification or stepwise dynamic thinning. A continuum hydrodynamic model is outlined for stepwise film thinning that incorporates equilibrium micellar structuring through self-consistent oscillatory disjoining pressures and effective viscosities. Effective viscosities as functions of thickness are evaluated with an extension of the local average density model, considering dilute colloidal suspension shear viscosities and solvent effects. To establish local shear viscosities, structured DFT micellar profiles, coarse-grained densities, and disjoining pressure are used. Ionic micelles and other colloidal systems with repulsive interactions show structured effective viscosities that are generally less than the corresponding homogeneous solution shear viscosity, bounded by the pure solvent viscosity and that of the bulk micellar solution. For 0.1 and 0.2-M sodium dodecylsulfate micellar solutions, the effective viscosities are less than 5 and 10%, respectively, below the homogeneous fluid viscosity, except at small thicknesses, indicating that the micellar film thins faster than a pure water film of the same thickness. Calculated thinning curves closely resemble experimental observations in the stepwise thinning behavior, displaying decreasing slopes and increased step durations at later times. Despite the micellar structuring within the film, the ionic micelles do not contribute appreciably to the viscous resistance of the thinning film. Rather, Reynolds` film thinning is obeyed, with the equilibrium oscillatory disjoining pressures driving the step-wise dynamics. The shear viscosity of the ionic micellar film is well approximated by that of the bulk solution.

Pollard, M.L.; Radke, C.J. [Lawrence Berkeley Lab., CA (United States)] [Lawrence Berkeley Lab., CA (United States)

1996-07-01

263

Lithium cation conducting TDI anion-based ionic liquids.  

PubMed

In this paper we present the synthesis route and electrochemical properties of new class of ionic liquids (ILs) obtained from lithium derivate TDI (4,5-dicyano-2-(trifluoromethyl)imidazolium) anion. ILs synthesized by us were EMImTDI, PMImTDI and BMImTDI, i.e. TDI anion with 1-alkyl-3-methylimidazolium cations, where alkyl meant ethyl, propyl and butyl groups. TDI anion contains fewer fluorine atoms than LiPF6 and thanks to C-F instead of P-F bond, they are less prone to emit fluorine or hydrogen fluoride due to the rise in temperature. Use of IL results in non-flammability, which is making such electrolyte even safer for both application and environment. The thermal stability of synthesized compounds was tested by DSC and TGA and no signal of decomposition was observed up to 250 °C. The LiTDI salt was added to ILs to form complete electrolytes. The structures of tailored ILs with lithium salt were confirmed by X-ray diffraction patterns. The electrolytes showed excellent properties regarding their ionic conductivity (over 3 mS cm(-1) at room temperature after lithium salt addition), lithium cation transference number (over 0.1), low viscosity and broad electrochemical stability window. The ionic conductivity and viscosity measurements of pure ILs are reported for reference. PMID:24803282

Niedzicki, Leszek; Karpierz, Ewelina; Zawadzki, Maciej; Dranka, Maciej; Kasprzyk, Marta; Zalewska, Aldona; Marcinek, Marek; Zachara, Janusz; Doma?ska, Urszula; Wieczorek, W?adys?aw

2014-06-21

264

Synthesis and characterization of ionic polymer networks in a room-temperature ionic liquid.  

PubMed

Ionic liquid gels (ILGs) for potential use in ion transport and separation applications were generated via a free radical copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and N,N'-methylene(bis)acrylamide (MBA) using 1-ethyl-3-methylimidazolium ethylsulfate (IL) as a room temperature ionic liquid solvent medium. The AMPS and MBA monomer solubility window in the IL in the temperature range of 25 to 65 °C was determined. In situ ATR-FTIR showed near complete conversion of monomers to a cross-linked polymer network. ILGs with glass transition temperatures (T(g)s) near -50 °C were generated with T(g) decreasing with increasing IL content. The elastic moduli in compression (200 to 6600 kPa) decreased with increasing IL content and increasing AMPS content while the conductivities (0.35 to 2.14 mS cm?¹) increased with increasing IL content and decreasing MBA content. The polymer-IL interaction parameter (?) (0.48 to 0.55) was determined via a modified version of the Bray and Merrill equation. PMID:23088450

Stanzione, Joseph F; Jensen, Robert E; Costanzo, Philip J; Palmese, Giuseppe R

2012-11-01

265

Covalent-to-ionic transition in liquid zinc dichloride  

NASA Astrophysics Data System (ADS)

We report molecular-dynamics simulations of self-diffusion and structure in a pseudoclassical model of liquid and crystalline ZnCl 2 over a wide region of the pressure-temperature plane. The model parameters are adjusted to reproduce a liquid structure of corner-sharing ZnCl 4 tetrahedra at the standard freezing point and the measured diffusion coefficients as functions of temperature on the sfp isobar. We find that compression first weakens the intermediate-range order of the melt near freezing into a fourfold-coordinated crystal structure, and then drives at higher temperatures a novel liquid-liquid transition consisting of two broad steps: (i) a transition in which the Zn atoms start to leave their tetrahedral cages, followed by (ii) a structural transition from a covalent network of Cl atoms to a dissociated ionic liquid which then freezes into a sixfold-coordinated crystal. Good agreement is found with data from X-ray diffraction experiments under pressure.

Ruberto, R.; Pastore, G.; Tosi, M. P.

2009-03-01

266

Redox-active cross-linkable poly(ionic liquid)s.  

PubMed

The synthesis of a new class of cross-linkable redox-responsive poly(ferrocenylsilane)-based poly(ionic liquid)s (PFS-PILs) is reported. PFS-PILs self-cross-link at low concentrations into nanogels or form macroscopic hydrogel networks at higher concentrations. PFS-PILs proved to be efficient dispersants in the microemulsion polymerization of methyl methacrylate, producing stable PFS-poly(methyl methacrylate) latex suspensions. PMID:22353019

Sui, Xiaofeng; Hempenius, Mark A; Vancso, G Julius

2012-03-01

267

Use of ionic liquids in a lipase-facilitated supported liquid membrane  

Microsoft Academic Search

A lipase-facilitated transport of 4-phenoxybutyric acid, 3-phenoxypropionic acid, 2-phenylpropionic acid, 2-phenoxybutyric acid, mandelic acid and 2-amino-2-phenylbutyric acid was carried out using a supported liquid membrane based on room temperature ionic liquids. There were marked differences in the permeate fluxes of various organic acids due to the substrate specificity of the lipases. The maximum permeate flux (44×10-2 mmol cm-2?×?h) was obtained using

Eijiro Miyako; Tatsuo Maruyama; Noriho Kamiya; Masahiro Goto

2003-01-01

268

Polarizability effects on the structure and dynamics of ionic liquids  

NASA Astrophysics Data System (ADS)

Polarization effects on the structure and dynamics of ionic liquids are investigated using molecular dynamics simulations. Four different ionic liquids were simulated, formed by the anions Cl- and PF6-, treated as single fixed charge sites, and the 1-n-alkyl-3-methylimidazolium cations (1-ethyl and 1-butyl-), which are polarizable. The partial charge fluctuation of the cations is provided by the electronegativity equalization model (EEM) and a complete parameter set for the cations electronegativity (?) and hardness (J) is presented. Results obtained from a non-polarizable model for the cations are also reported for comparison. Relative to the fixed charged model, the equilibrium structure of the first solvation shell around the imidazolium cations shows that inclusion of EEM polarization forces brings cations closer to each other and that anions are preferentially distributed above and below the plane of the imidazolium ring. The polarizable model yields faster translational and reorientational dynamics than the fixed charges model in the rotational-diffusion regime. In this sense, the polarizable model dynamics is in better agreement with the experimental data.

Cavalcante, Ary de Oliveira; Ribeiro, Mauro C. C.; Skaf, Munir S.

2014-04-01

269

Development of an Ionic-Liquid Absorption Heat Pump  

SciTech Connect

Solar Fueled Products (SFP) is developing an innovative ionic-liquid absorption heat pump (ILAHP). The development of an ILAHP is extremely significant, as it could result in annual savings of more than 190 billion kW h of electrical energy and $19 billion. This absorption cooler uses about 75 percent less electricity than conventional cooling and heating units. The ILAHP also has significant environmental sustainability benefits, due to reduced CO2 emissions. Phase I established the feasibility and showed the economic viability of an ILAHP with these key accomplishments: • Used the breakthrough capabilities provided by ionic liquids which overcome the key difficulties of the common absorption coolers. • Showed that the theoretical thermodynamic performance of an ILAHP is similar to existing absorption-cooling systems. • Established that the half-effect absorption cycle reduces the peak generator temperature, improving collector efficiency and reducing collector area. • Component testing demonstrated that the most critical components, absorber and generator, operate well with conventional heat exchangers. • Showed the economic viability of an ILAHP. The significant energy savings, sustainability benefits, and economic viability are compelling reasons to continue the ILAHP development.

Holcomb, Don

2011-03-29

270

Solution and thermal behaviour of novel dicationic imidazolium ionic liquids.  

PubMed

A new class of functionalised dicationic ionic liquids, containing a central cationic unit capped by a basic functionality (imidazole), has been synthesised. These salts have been characterised in isotropic solution using proton and 2D-NMR spectroscopy, and their thermal stability has been studied by DSC and TGA. All these novel salts contain the 1-(1-imidazolylmethyl)-3,5-di{1-(3'-octylimidazolylmethyl)}-benzene cation as a defining structural motif. Salts of both singly and doubly charged anions were prepared and, in particular, the selected monoanions (Br(-), [BF4](-), or [NTf2](-)) differ in size, shape and hydrogen-bonding ability, whereas the dianions differ in the nature of the spacer, such as 1,4-benzenedicarboxylate, 2,6-naphthalenedicarboxylate, 1,5- and 2,6-naphthalenedisulfonate, 1,4-butanedicarboxylate, and 1,6-hexanedicarboxylate. These ionic liquids exhibit the presence of different conformers in solution, whose distribution is affected by the nature of the anion. The nature of the anion also affects their thermal stability. PMID:23900265

D'Anna, Francesca; Gunaratne, H Q Nimal; Lazzara, Giuseppe; Noto, Renato; Rizzo, Carla; Seddon, Kenneth R

2013-09-21

271

Dialkylimidazolium ionic liquids hydrolyze cellulose under mild conditions.  

PubMed

The average molecular weight of cellulose derived from filter paper, poplar, and Avicel decreases by up to two orders of magnitude during typical mild dissolution protocols using ionic liquids (ILs). About an order of magnitude greater cellulose depolymerization rate during ionic liquid dissolution occurs in 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-ethyl-3-methylimidazolium chloride (EmimCl) compared to 1-ethyl-3-methylimidazolium acetate (EmimOAc), and, unintuitively, greater IL purity results in greater cellulose depolymerization. The following data support the mechanism of cellulose hydrolysis to be acid-catalyzed: (i) increase in number of reducing ends following cellulose dissolution in IL; (ii) addition of N-methylimidazolium base suppresses cellulose depolymerization during dissolution in IL; (iii) small amounts of glucose and traces of hydroxymethyl furfural are present following cellulose dissolution in IL. The acid is presumably synthesized via IL decomposition to generate a carbene and proton, consistent with hypothesis derived from molecular modeling. Titration experiments conducted here measure the amount of acid synthesized to be in the 4000 ppm range for high-purity BmimCl IL during mild processing conditions for cellulose dissolution. This data is relevant for understanding the extent of IL decomposition during biomass dissolution. PMID:22550059

Gazit, Oz M; Katz, Alexander

2012-08-01

272

Imidazolium-based ionic liquid surfaces for biosensing.  

PubMed

Ionic liquid self-assembled monolayers (SAM) were designed and applied for binding streptavidin, promoting affinity biosensing and enzyme activity on gold surfaces of sensors. The synthesis of 1-((+)-biotin)pentanamido)propyl)-3-(12-mercaptododecyl)-imidazolium bromide, a biotinylated ionic liquid (IL-biotin), which self-assembles on gold film, afforded streptavidin sensing with surface plasmon resonance (SPR). The IL-biotin-SAM efficiently formed a full streptavidin monolayer. The synthesis of 1-(carboxymethyl)-3-(mercaptododecyl)-imidazoliumbromide, a carboxylated IL (IL-COOH), was used to immobilize anti-IgG to create an affinity biosensor. The IL-COOH demonstrated efficient detection of IgG in the nanomolar concentration range, similar to the alkylthiols SAM and PEG. In addition, the IL-COOH demonstrated low fouling in crude serum, to a level equivalent to PEG. The IL-COOH was further modified with N,N'-bis (carboxymethyl)-l-lysine hydrate to bind copper ions and then, chelate histidine-tagged biomolecules. Human dihydrofolate reductase (hDHFR) was chelated to the modified IL-COOH. By monitoring enzyme activity in situ on the SPR sensor, it was revealed that the IL-COOH SAM improved the activity of hDHFR by 24% in comparison to classical SAM. Thereby, IL-SAM has been synthesized and successfully applied to three important biosensing schemes, demonstrating the advantages of this new class of monolayers. PMID:23706008

Ratel, Mathieu; Provencher-Girard, Audrey; Zhao, Sandy Shuo; Breault-Turcot, Julien; Labrecque-Carbonneau, Jérémie; Branca, Mathieu; Pelletier, Joelle N; Schmitzer, Andreea R; Masson, Jean-Francois

2013-06-18

273

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

274

Influence of water on the surface of hydrophilic and hydrophobic room-temperature ionic liquids.  

PubMed

Vibrational spectroscopy, sum frequency generation, has been used to study the gas-liquid interface of imidazolium-based, room-temperature ionic liquids. The ionic liquids are divided into two categories on the basis of their miscibility with water, as hydrophobic (immiscible) and hydrophilic (miscible). The spectroscopy results indicate that water will reorient the cations of the hydrophobic ionic liquid, while in the hydrophilic ones they remain unaffected. Thus, under low water conditions the plane of the imidazolium ring remains parallel to the surface for both types of ionic liquid. However, at high water content the ring will reorient to along the surface normal for the hydrophobic ionic liquid but remain parallel to the surface for the hydrophilic one. This is a reversible process. PMID:15382902

Rivera-Rubero, Selimar; Baldelli, Steven

2004-09-29

275

Ionic Liquids and New Proton Exchange Membranes for Fuel Cells  

NASA Technical Reports Server (NTRS)

There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

Belieres, Jean-Philippe

2004-01-01

276

Cold crystallisation behaviour of water molecules in ionic liquids as a screening method to evaluate biocompatibility of the hydrated ionic liquids.  

PubMed

Hydrated ionic liquids, exhibiting cold crystallisation behaviour of water molecules in a certain range of water contents, successfully dissolved cytochrome c maintaining the original spin state of heme. PMID:23486783

Fujita, Kyoko; Nikawa, Yohsuke; Ohno, Hiroyuki

2013-04-21

277

Enhanced electrical transport in ionic liquid dispersed TMAI-PEO solid polymer electrolyte  

NASA Astrophysics Data System (ADS)

A polymer composite is prepared by dispersing ionic liquid [Bmim][BF4] in Polyethylene oxide-tetra methyl ammonium iodide composite and subsequent microwave treatment. X-ray diffraction patterns confirm the composite nature. To explore possibility of proton conductivity in these films, electrical transport is studied by impedance spectroscopy and DC polarization. It is revealed that addition of ionic liquid in host TMAI-PEO solid polymer electrolyte enhances the conductivity by ˜ 2 orders of magnitude. Polarization measurements suggest that composites are essentially ion conducting in nature. The maximum ionic conductivity is found to be ˜2 × 10-5 for 10 wt % ionic liquid.

Gupta, Neha; Rathore, Munesh; Dalvi, Anshuman; Kumar, Anil

2014-04-01

278

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

PubMed

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 the determination of gas-liquid partition coefficients and activity coefficients as well as thermodynamic constants derived from either of these parameters and their variation with temperature. The solvation parameter model can be used to define the contribution from individual intermolecular interactions to the gas-liquid partition coefficient. Application of chemometric procedures to a large database of system constants for ionic liquids indicates their unique solvent properties: low cohesion for ionic liquids with weakly associated ions compared with non-ionic liquids of similar polarity; greater hydrogen-bond basicity than typical polar non-ionic solvents; and a range of dipolarity/polarizability that encompasses the same range as occupied by the most polar non-ionic liquids. These properties can be crudely related to ion structures but further work is required to develop a comprehensive approach for the design of ionic liquids for specific applications. Data for liquid-liquid partition coefficients is scarce by comparison with gas-liquid partition coefficients. Preliminary studies indicate the possibility of using the solvation parameter model for interpretation of liquid-liquid partition coefficients determined by shake-flask procedures as well as the feasibility of using liquid-liquid chromatography for the convenient and rapid determination of liquid-liquid partition coefficients. Spectroscopic measurements of solvatochromic and fluorescent probe molecules in room temperature ionic liquids provide insights into solvent intermolecular interactions although interpretation of the different and generally uncorrelated "polarity" scales is sometimes ambiguous. All evidence points to the ionic liquids as a unique class of polar solvents suitable for technical development. In terms of designer solvents, however, further work is needed to fill the gaps in our knowledge of the relationship between ion structures and physicochemical properties. PMID:15214660

Poole, Colin F

2004-05-28

279

Adsorption behavior of Pd (II) using pyridine series ionic liquid and inorganic substrate-ionic liquid composite material  

NASA Astrophysics Data System (ADS)

Adsorption behavior of Pd(II) chloride complexes using pyridine series ionic liquid (BPHFP) was investigated to establish a clean Pd(II) recovered process by use of ionic liquids as an adsorvent. Adsorption amount of Pd(II) to BPHFP reached a maximum under a low HCl concentration. This is a similar result using a traditional ion-exchange resin, however, no Langmuir adsorption behavior was confirmed in the case of Pd(II) concentration of 1-50 mmol?dm3. PdCl2 exists as a soluble monomeric PdCl42- species in higher HCl concentration solution. On the other hand, an insoluble polymeric Pd species is generated in the solution of low HCl concentration. These results indicaled that Pd(II) adsorption using BPHFP was controlled by chemisorption, and the direct coordination of Pd(II) onto pyridine was possibly occurred. Moreover, inorganic support-BPHFP composite material (ILISP) was also developed. The ILISP showed an availability as a Pd(II) adsorbent.

Ikeda, Yasuyuki; Inoue, Ryo; Arai, Tsuyoshi

280

Thermal properties of ionic systems near the liquid-liquid critical point.  

PubMed

Isobaric heat capacity per unit volume, C(p), and excess molar enthalpy, h(E), were determined in the vicinity of the critical point for a set of binary systems formed by an ionic liquid and a molecular solvent. Moreover, and, since critical composition had to be accurately determined, liquid-liquid equilibrium curves were also obtained using a calorimetric method. The systems were selected with a view on representing, near room temperature, examples from clearly solvophobic to clearly coulombic behavior, which traditionally was related with the electric permittivity of the solvent. The chosen molecular compounds are: ethanol, 1-butanol, 1-hexanol, 1,3-dichloropropane, and diethylcarbonate, whereas ionic liquids are formed by imidazolium-based cations and tetrafluoroborate or bis-(trifluromethylsulfonyl)amide anions. The results reveal that solvophobic critical behavior-systems with molecular solvents of high dielectric permittivity-is very similar to that found for molecular binary systems. However, coulombic systems-those with low permittivity molecular solvents-show strong deviations from the results usually found for these magnitudes near the liquid-liquid phase transition. They present an extremely small critical anomaly in C(p)-several orders of magnitude lower than those typically obtained for binary mixtures-and extremely low h(E)-for one system even negative, fact not observed, up to date, for any liquid-liquid transition in the nearness of an upper critical solution temperature. PMID:22149802

Méndez-Castro, Pablo; Troncoso, Jacobo; Pérez-Sánchez, Germán; Peleteiro, José; Romaní, Luis

2011-12-01

281

Thermal properties of ionic systems near the liquid-liquid critical point  

NASA Astrophysics Data System (ADS)

Isobaric heat capacity per unit volume, Cp, and excess molar enthalpy, hE, were determined in the vicinity of the critical point for a set of binary systems formed by an ionic liquid and a molecular solvent. Moreover, and, since critical composition had to be accurately determined, liquid-liquid equilibrium curves were also obtained using a calorimetric method. The systems were selected with a view on representing, near room temperature, examples from clearly solvophobic to clearly coulombic behavior, which traditionally was related with the electric permittivity of the solvent. The chosen molecular compounds are: ethanol, 1-butanol, 1-hexanol, 1,3-dichloropropane, and diethylcarbonate, whereas ionic liquids are formed by imidazolium-based cations and tetrafluoroborate or bis-(trifluromethylsulfonyl)amide anions. The results reveal that solvophobic critical behavior--systems with molecular solvents of high dielectric permittivity--is very similar to that found for molecular binary systems. However, coulombic systems--those with low permittivity molecular solvents--show strong deviations from the results usually found for these magnitudes near the liquid-liquid phase transition. They present an extremely small critical anomaly in Cp--several orders of magnitude lower than those typically obtained for binary mixtures--and extremely low hE--for one system even negative, fact not observed, up to date, for any liquid-liquid transition in the nearness of an upper critical solution temperature.

Méndez-Castro, Pablo; Troncoso, Jacobo; Pérez-Sánchez, Germán; Peleteiro, José; Romaní, Luis

2011-12-01

282

Ionic liquids and ionic liquid acids with high temperature stability for fuel cell and other high temperature applications, method of making and cell employing same  

Microsoft Academic Search

Disclosed are developments in high temperature fuel cells including ionic liquids with high temperature stability and the storage of inorganic acids as di-anion salts of low volatility. The formation of ionically conducting liquids of this type having conductivities of unprecedented magnitude for non-aqueous systems is described. The stability of the di-anion configuration is shown to play a role in the

C. Austen Angell; Wu Xu; Jean-Philippe Belieres; Masahiro Yoshizawa

2011-01-01

283

Ionic liquids in soils: effects of different anion species of imidazolium based ionic liquids on wheat ( Triticum aestivum ) as affected by different clay minerals and clay concentrations  

Microsoft Academic Search

This study contributes to a prospective hazard assessment of ionic liquids, focusing on the terrestrial environment. The influence\\u000a of differently composed soils—varying contents of the clay minerals smectite and kaolinite—on the toxicity of different anion\\u000a species of imidazolium based ionic liquids was studied for growth inhibition of wheat (Triticum aestivum). IM14 (CF3SO2)2N appeared the most toxic, independently of the investigated

Marianne Matzke; Stefan Stolte; Jürgen Arning; Ute Uebers; Juliane Filser

2009-01-01

284

Highly ion conductive flexible films composed of network polymers based on polymerizable ionic liquids  

Microsoft Academic Search

Ionic liquid-type polymer brushes having different hydrocarbon (HC) chain lengths between polymerizable group and imidazolium ring were synthesized. When the carbon number of HC chain was 6, the ionic liquid-type polymer brush exhibited the highest ionic conductivity of 1.37×10?4Scm?1 at 30 °C, reflecting low Tg of ?60 °C. Moreover, for the first time, we succeeded in obtaining transparent and flexible

Satoko Washiro; Masahiro Yoshizawa; Hiromitsu Nakajima; Hiroyuki Ohno

2004-01-01

285

A neat ionic liquid electrolyte based on FSI anion for electric double layer capacitor  

Microsoft Academic Search

An ionic liquid, 1-ethyl-3-methyl imidazolium bis(fluorosulfonyl)imide (EMI-FSI), has been applied to an electrolyte for electric double layer capacitors (EDLCs). The electrolyte exhibited high ionic conductivity comparable to that of a conventional organic electrolyte. EDLC prepared with EMI-FSI showed excellent rate capability although the electrolyte is a neat ionic liquid; this performance was observed irrespective of the presence of a binder

Norihisa Handa; Toshinori Sugimoto; Masaki Yamagata; Manabu Kikuta; Michiyuki Kono; Masashi Ishikawa

2008-01-01

286

Role of Dissolved Gas in Ionic Liquid Electrolytes for Secondary Lithium Metal Batteries.  

National Technical Information Service (NTIS)

The effect of dissolved gas on the reversibility of a Li/Li+ electrode in an ionic liquid electrolyte was investigated. Lithium metal is a potential anode in lithium batteries. The ionic liquid electrolyte was saturated with argon, nitrogen, oxygen, air, ...

J. K. Stark P. A. Kohl Y. Ding

2013-01-01

287

Catalysed esterifications in room temperature ionic liquids with acidic counteranion as recyclable reaction media  

Microsoft Academic Search

Esterification reactions of acetic acid, methoxyacetic acid and methylmalonic acid with neo-pentanol, hexanol, heptanol and decanol have been investigated in three ionic liquids with hydrogen sulphate, dihydrogen phosphate as counteranions and also two ionic liquids modified with HPF6 as catalyst. The nature of both the counteranion and cation influence the behavior of the catalyst. Good yields and high selectivities were

Joan Fraga-Dubreuil; Khadidja Bourahla; Mustapha Rahmouni; Jean Pierre Bazureau; Jack Hamelin

2002-01-01

288

Reductive amination of carbonyl compounds using NaBH 4 in a Brønsted acidic ionic liquid  

Microsoft Academic Search

Reductive amination of carbonyl compounds using sodium borohydride is conducted in the Brønsted acidic ionic liquid, 1-methyl imidazolium tetrafluoroborate ([HMIm][BF4]). The ionic liquid plays the dual role of solvent as well as catalyst for efficient conversion of aldehydes and ketones to amines in excellent yields without the formation of side products.

P. Srinivasa Reddy; Sanjit Kanjilal; S. Sunitha; Rachapudi B. N. Prasad

2007-01-01

289

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

National Technical Information Service (NTIS)

The overall goal of this project is to develop a new ionic liquid based solvent extraction process for separation of Cs- 137 and Sr-90 from tank wastes. To synthesize new ionic liquids tailored for the extractive separation of Cs+ and Sr2+. To select opti...

H. Luo S. Dai P. V. Bonnesen A. C. Buchanan

2005-01-01

290

Selection of ionic liquids for the extraction of aromatic hydrocarbons from aromatic\\/aliphatic mixtures  

Microsoft Academic Search

The separation of aromatic hydrocarbons (benzene, toluene, ethyl benzene and xylenes) from C4 to C10 aliphatic hydrocarbon mixtures is challenging since these hydrocarbons have boiling points in a close range and several combinations form azeotropes. In this work, we investigated the separation of toluene from heptane by extraction with ionic liquids.Several ionic liquids are suitable for extraction of toluene from

G. Wytze Meindersma; André B. de Haan

2005-01-01

291

Highly efficient reduction of ferrocenyl aldehyde and ketones in ionic liquids  

Microsoft Academic Search

For the first time ferrocenyl aldehyde and ketones were effectively reduced to alkylferrocene using sodium borohydride and aluminum chloride in an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm]BF4). Mild reaction conditions, enhanced rates, improved yields, and recyclable ionic liquid are the remarkable features exhibited in this process.

Hongyan Zhang; Zhanxi Bian

2007-01-01

292

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

293

Cytotoxicity estimation of ionic liquids based on their effective structural features  

Microsoft Academic Search

Cytotoxicity of a diverse set of 227 ionic liquids (taken from UFT\\/Merck Ionic Liquids Biological Effects Database) containing 94 imidazolium, 53 pyridinium, 23 pyrrolidinium, 22 ammonium, 15 piperidinium, 10 morpholinium, 5 phosphanium, and 5 quinolinium cations in combination with 25 different types of anions to Leukemia Rat Cell Line (IPC-81) was estimated from their structural parameters using quantitative structure –

Mohammad H. Fatemi; Parisa Izadiyan

2011-01-01

294

Promotion of Atom Transfer Radical Polymerization and Ring-Opening Metathesis Polymerization in Ionic Liquids  

Microsoft Academic Search

In the last decade, there has been an increasing interest in using ionic liquids as solvents for chemical reactions and polymerizations. This interest is stimulated not only by their nonvolatility (green solvents) but also by their special properties, which often affect the course of a reaction or polymerization and the properties of products. Recent developments in ionic liquids as solvents

Meiran Xie; Huijing Han; Liang Ding; Jiaxin Shi

2009-01-01

295

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

296

Interatomic force modelling of local coordination and extended structure in ionic-covalent liquids  

Microsoft Academic Search

Liquid-state studies on families of stoichiometric compounds, and on mixtures that are stable in the liquid phase over large ranges of composition, offer a unique opportunity to explore trends in the evolution of bonding between the ionic, metallic and covalent canonical forms. The present work is primarily focused on the evolution from mainly ionic to increasingly covalent bonding character in

A. Ferrante; Wang Li; M. P. Tosi

1988-01-01

297

Polyanionic and polyzwitterionic azobenzene ionic liquid-functionalized silica materials and their chromatographic applications.  

PubMed

New polyanionic and polyzwitterionic azobenzene ionic liquid-functionalized silica materials were designed based on the preparation of a new polymerizable azobenzene anionic monomer and either its cation-exchange with alkylimidazolium after grafting or the formation of an ionic liquid monomer pair before grafting onto silica. PMID:23417018

Qiu, Hongdeng; Jiang, Shengxiang; Takafuji, Makoto; Ihara, Hirotaka

2013-03-25

298

Ionic liquids as electrolytes for Li-ion batteries—An overview of electrochemical studies  

Microsoft Academic Search

The paper reviews properties of room temperature ionic liquids (RTILs) as electrolytes for lithium and lithium-ion batteries. It has been shown that the formation of the solid electrolyte interface (SEI) on the anode surface is critical to the correct operation of secondary lithium-ion batteries, including those working with ionic liquids as electrolytes. The SEI layer may be formed by electrochemical

Andrzej Lewandowski; Agnieszka ?widerska-Mocek

2009-01-01

299

Effect of a novel amphipathic ionic liquid on lithium deposition in gel polymer electrolytes  

Microsoft Academic Search

A novel dimeric ionic liquid based on imidazolium cation and bis(trifluoromethanesulfonyl) imide (TFSI) anion has been synthesized through a metathesis reaction. Its chemical shift values and thermal properties are identified via 1H nuclear magnetic resonance (NMR) imaging and differential scanning calorimetry (DSC). The effect of the synthesized dimeric ionic liquid on the interfacial resistance of gel polymer electrolytes is described.

Nam-Soon Choi; Bonjae Koo; Jin-Tak Yeon; Kyu Tae Lee; Dong-Won Kim

2011-01-01

300

Ionic liquid electrolyte systems based on bis(fluorosulfonyl)imide for lithium-ion batteries  

Microsoft Academic Search

Ionic liquid electrolytes containing a certain amount of bis(fluorosulfonyl)imide (FSI) anion can provide reversible capacity for a graphitized negative electrode without any additives such as a solvent. Cyclic voltammetry for a graphitized negative electrode in ionic liquid electrolytes containing FSI with other anions suggests that the reversibility of Li intercalation correlates with the relative quantity (or concentration) of FSI in

Toshinori Sugimoto; Yosuke Atsumi; Manabu Kikuta; Eriko Ishiko; Michiyuki Kono; Masashi Ishikawa

2009-01-01

301

Nonhumidified intermediate temperature fuel cells using protic ionic liquids.  

PubMed

In this paper, the characterization of a protic ionic liquid, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]), as a proton conductor for a fuel cell and the fabrication of a membrane-type fuel cell system using [dema][TfO] under nonhumidified conditions at intermediate temperatures are described in detail. In terms of physicochemical and electrochemical properties, [dema][TfO] exhibits high activity for fuel cell electrode reactions (i.e., the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR)) at a Pt electrode, and the open circuit voltage (OCV) of a liquid fuel cell is 1.03 V at 150 degrees C, as has reported in ref 27. However, diethylmethylammonium bis(trifluoromethane sulfonyl)amide ([dema][NTf(2)]) has relatively low HOR and ORR activity, and thus, the OCV is ca. 0.7 V, although [dema][NTf(2)] and [dema][TfO] have an identical cation ([dema]) and similar thermal and bulk-transport properties. Proton conduction occurs mainly via the vehicle mechanism in [dema][TfO] and the proton transference number (t(+)) is 0.5-0.6. This relatively low t(+) appears to be more disadvantageous for a proton conductor than for other electrolytes such as hydrated sulfonated polymer electrolyte membranes (t(+) = 1.0). However, fast proton-exchange reactions occur between ammonium cations and amines in a model compound. This indicates that the proton-exchange mechanism contributes to the fuel cell system under operation, where deprotonated amines are continuously generated by the cathodic reaction, and that polarization of the cell is avoided. Six-membered sulfonated polyimides in the diethylmethylammonium form exhibit excellent compatibility with [dema][TfO]. The composite membranes can be obtained up to a [dema][TfO] content of 80 wt % and exhibit good thermal stability, high ionic conductivity, and mechanical strength and gas permeation comparable to those of hydrated Nafion. H(2)/O(2) fuel cells prepared using the composite membranes can successfully operate at temperatures from 30 to 140 degrees C under nonhumidified conditions, and a current density of 250 mA cm(-2) is achieved at 120 degrees C. The protic ionic liquid and its composite membrane are a possible candidate for an electrolyte of a H(2)/O(2) fuel cell that operates under nonhumidified conditions. PMID:20578771

Lee, Seung-Yul; Ogawa, Atsushi; Kanno, Michihiro; Nakamoto, Hirofumi; Yasuda, Tomohiro; Watanabe, Masayoshi

2010-07-21

302

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

2011-09-01

303

The ecotoxicity of ionic liquids and traditional organic solvents on microalga Selenastrum capricornutum.  

PubMed

In this study, the effects of several ionic liquids and traditional organic solvents on the growth of the green microalga, Selenastrum capricornutum, were investigated. The toxicities were strongly related to the incubation time and chemical structures of the ionic liquids. The toxicities of tetrabutylphosphonium and tetrabutylammonium containing bromide anion were observed to decrease when the incubation time was raised from 48 to 96 h. Conversely, the toxicities of 1-butyl-3-methylimidazolium and 1-butyl-3-methylpyridinium containing bromide anion were found to increase with increasing incubation time. Of the ionic liquids tested, 1-butyl-1-methylpyrrolidinium bromide was found to be the least toxic, which is similar in toxicity level of dimethylformamide. In general, the toxicities of the ionic liquids were estimated to be two and four orders of magnitude greater than those of the organic solvents examined, although ionic liquids are being considered as green solvents. PMID:17692914

Cho, Chul-Woong; Jeon, You-Chul; Pham, Thi Phuong Thuy; Vijayaraghavan, K; Yun, Yeoung-Sang

2008-09-01

304

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

305

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

306

Shape selectivity using ionic liquids for the preparation of silver and silver sulphide nanomaterials.  

PubMed

Electrodeposition of silver and silver sulphide was carried out from two protic ionic liquids. A change of the anion moiety of ionic liquid was found to bring about significant changes in the morphology of the nanocrystalline silver and silver sulphide deposits obtained. Effects of various parameters like deposition overpotential, change of the substrate, deposition time, etc. on the particle size and shape were studied. It was found that a change of anions of the ionic liquid from acetate to nitrate results in a wide difference in the morphology of the deposits obtained. Acetate containing ionic liquids result in globular nanocrystalline deposits whereas nitrate containing ionic liquids result in flat plates or sheets of silver deposits. Similar results were obtained for silver sulphide nanocrystals. PMID:24394372

Patil, Amol B; Bhanage, Bhalchandra M

2014-02-21

307

Contracting cardiomyocytes in hydrophobic room-temperature ionic liquid  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Biocompatible room-temperature ionic liquid was applied on beating cardiomyocyte. Black-Right-Pointing-Pointer The lifetime of beating cardiomyocytes was depended on anion functional group. Black-Right-Pointing-Pointer A longer lifetime was recorded for no functional group on alkyl chain on their anion. Black-Right-Pointing-Pointer Amino group on alkyl chain and fluorine in anion induced fatal condition changes. Black-Right-Pointing-Pointer We reported liquid electrolyte interface to stimulate cardiomyocytes. -- Abstract: Room-temperature ionic liquids (RTILs) are drawing attention as a new class of nonaqueous solvents to replace organic and aqueous solvents for chemical processes in the liquid phase at room temperature. The RTILs are notable for their characteristics of nonvolatility, extremely low vapor pressure, electric conductivity, and incombustibility. These distinguished properties of RTILs have brought attention to them in applications with biological cells and tissue in vacuum environment for scanning electron microscopy, and in microfluidic devices for micro-total analysis system (micro-TAS). Habitable RTILs could increase capability of nonaqueous micro-TAS for living cells. Some RTILs seemed to have the capability to replace water in biological applications. However, these RTILs had been applied to just supplemental additives for biocompatible test, to fixed cells as a substitute for an aqueous solution, and to simple molecules. None of RTILs in which directly soaks a living cell culture. Therefore, we demonstrated the design of RTILs for a living cell culture and a liquid electrolyte to stimulate contracting cardiomyocytes using the RTILs. We assessed the effect of RTILs on the cardiomyocytes using the beating lifetime to compare the applicability of RTILs for biological applications. Frequent spontaneous contractions of cardiomyocytes were confirmed in amino acid anion RTILs [P{sub 8,8,8,8}][Leu] and [P{sub 8,8,8,8}][Ala], phosphoric acid derivatives [P{sub 8,8,8,8}][MeO(H)PO{sub 2}], and [P{sub 8,8,8,8}][C{sub 7}CO{sub 2}]. The anion type of RTILs had influence on applicable characteristics for the contracting cardiomyocyte. This result suggested the possibility for biocompatible design of hydrophobic group RTILs to achieve biological applications with living cells.

Hoshino, Takayuki [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Fujita, Kyoko [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)] [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Higashi, Ayako; Sakiyama, Keiko [Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)] [Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Ohno, Hiroyuki [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)] [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Morishima, Keisuke, E-mail: morishima@mech.eng.osaka-u.ac.jp [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)

2012-10-19

308

Ion Transport in Polymerized Ionic Liquid Block and Random Copolymers  

NASA Astrophysics Data System (ADS)

Polymerized ionic liquid (PIL) block copolymers, a new type of solid-state polymer electrolyte, are of interest for energy conversion and storage devices, such as fuel cells, batteries, supercapacitors, and solar cells. In this study, a series of PIL diblock and random copolymers with various PIL compositions were synthesized. These consisted of an IL monomer and a non-ionic monomer, 1-[(2-methacryloyloxy)ethyl]-3-butylimidazolium bis(trifluoromethanesulfonyl)imide (MEBIm-TFSI) and methyl methacrylate (MMA), and 1-[(2-acryloyloxy)ethyl]-3-butylimidazolium bis(trifluoromethanesulfonyl)imide (AEBIm-TFSI) and styrene (S), respectively, were synthesized. The anion conductivity (ion transport) and morphology were measured in all of the polymers with EIS, SAXS/WAXS, and TEM. Ion transport in block copolymers are significantly higher than random copolymers at the same PIL composition and are highly dependent on the block copolymer nanostructure. The relationship between ion transport mechanisms and the phase behavior of these materials will be discussed.

Elabd, Yossef; Ye, Yuesheng; Choi, Jae-Hong; Winey, Karen

2012-02-01

309

Benzonitrile as a probe of local environment in ionic liquids.  

PubMed

Because of its sensitivity to chemical and electrostatic characteristics, nitrile group as an infrared (IR) probe to monitor the local structure, folding kinetics, and electrostatic environment of protein, or solvation of molecular solvents, has attracted increasing attention. Herein, by choosing benzonitrile and imidazolium ionic liquids (ILs) as the IR probe and model ILs, respectively, we report that the nitrile stretching vibration (?CN) could be utilized as a simple and substantial IR probe to monitor the local environment of ILs such as hydrogen bonding (H-bonding) as well as intrinsic electric field. In 1-alkyl-3-methylimidazolium-based non-hydroxyl ILs, the ?CN is in a "free" state, and is less affected by the alkyl chain, while it significantly decreases with the effective anion charge. In 1-(2-hydroxyethyl)-3-methylimidazolium-based hydroxyl ILs, however, a distinct anion-dependent ?CN forming H-bonding with the hydroxyl is also observed besides the "free" ?CN band. The "free" component of ?CN can be further employed to determine the intrinsic electric field in both non-hydroxyl (directly) and hydroxyl (indirectly by subtracting H-bonding contribution) ILs by using vibrational Stark effect. Moreover, the result suggests that benzonitrile is preferentially located in the charge domain in ILs and it could be a more suitable probe to report the ionic network rather than the nonpolar domain in ILs. PMID:23398446

Zhang, Shiguo; Zhang, Yan; Ma, Xiangyuan; Lu, Liujin; He, Yude; Deng, Youquan

2013-03-01

310

The Solubility of Ionic Solids and Molecular Liquids  

NASA Astrophysics Data System (ADS)

Solubility is a ubiquitous concept in chemistry, but usually only sparingly soluble salts are examined in the introductory chemistry laboratory. With this two-part experiment, students study more common solubility phenomena. First, solubilities of three ionic salts (NaCl, PbCl2, and KAl(SO4)2.12H2O) in water are measured at four temperatures. The concept of recrystallization is introduced as students cool a high-temperature solution and observe crystal formation. Class data are pooled and students are expected to identify and exclude poor data. Spreadsheet calculations are performed with the group data, which are then graphed, and students observe the wide variance in solubility behavior for the three salts. In the second part of the experiment, water and six organic liquids are mixed pairwise in all possible combinations to determine which pairs are miscible. Dielectric constants are provided for each liquid as a measure of polarity and students are asked to discuss their observed solubilities in terms of polarity. The common rule of "like dissolves like" is found to be less than satisfactory as a description of liquid solubility behavior if too narrowly interpreted.

Baer, C.; Adamus, Sheila M.

1999-11-01

311

Rheology of protic ionic liquids and their mixtures.  

PubMed

The rheological properties of five pure protic ionic liquids (ILs), ethylammonium nitrate (EAN), propylammonium nitrate (PAN), ethanolammonium nitrate (EtAN), ethylammonium formate (EAF), and dimethylethylammonium formate (DMEAF), are characterized and interpreted by considering the effects of both the H-bond network and the solvophobic nanostructure of the liquids. The results demonstrate that these effects are not, however, independent or simply additive. At 20 °C, EtAN has the highest zero shear viscosity of 156.1 mPa·s, followed by PAN (89.3 mPa·s), EAN (35.9 mPa·s), EAF (23.1 mPa·s), and DMEAF (9.8 mPa·s). The primary ammonium ILs behave as Newtonian fluids at low shear rates but shear thin at high shear. Fits to the Vogel-Fulcher-Tammann model reveal that nanostructure is not affected appreciably by temperature and that all the ILs studied are of intermediate fragility. The rheology of binary mixtures of these ILs was analyzed and used to demonstrate fundamental differences in the way IL cations and anions interact. IL mixtures containing both nitrate and formate anions resist flow more strongly than the pure liquids, which is a consequence of the difference in hydrogen bonding capacity of the anions. Mixing cations can give rise to complex behavior due to the offsetting effects of hydrogen bonding and solvophobic nanostructure formation. PMID:24102175

Smith, J A; Webber, Grant B; Warr, Gregory G; Atkin, Rob

2013-11-01

312

Saturation Properties of 1-Alkyl-3-methylimidazolium Based Ionic Liquids.  

PubMed

We study the liquid-vapor saturation properties of room temperature ionic liquids (RTILs) belonging to the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) using Monte Carlo simulation. We examine the effect of temperature and cation alkyl chain length n on the saturated densities, vapor pressures, and enthalpies of vaporization. These properties are explicitly calculated for temperatures spanning from 280 to 1000 K for RTILs with n = 2, 4, 6, 8, 10, and 12. We also explore how the identity of the anion influences saturation properties. Specifically, we compare results for [C4mim][NTf2] with those for 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]). Simulations are completed with a recently developed realistic united-atom force field. A combination of direct grand canonical and isothermal-isobaric temperature expanded ensemble simulations are used to construct phase diagrams. Our results are compared with experimental data and Gibbs ensemble simulation data. Overall, we find good agreement between our results and those measured experimentally. We find that the vapor pressures and enthalpies of vaporization show a strong dependence on the size of the alkyl chain at low temperatures, whereas no particular trend is observed at high temperatures. Finally, we also discuss the effect of temperature on liquid phase nanodomains observed in RTILs with large hydrophobic groups. We do not observe a drastic change in liquid phase structure upon variation of the temperature, which suggests there is not a sharp phase transition between a nanostructured and homogeneous liquid, as has been suggested in earlier studies. PMID:24986360

Rane, Kaustubh S; Errington, Jeffrey R

2014-07-24

313

Cyanoborohydride-based ionic liquids as green aerospace bipropellant fuels.  

PubMed

In propellant systems, the most common bipropellants are composed of two chemicals, a fuel (or reducer) and an oxidizer. Currently, the choices for propellant fuels rely mainly on hydrazine and its methylated derivatives, even though they are extremely toxic, highly volatile, sensitive to adiabatic compression (risk of detonation), and, therefore, difficult to handle. With this background, the search for alternative green propellant fuels has been an urgent goal of space science. In this study, a new family of cyanoborohydride-based ionic liquids (ILs) with properties and performances comparable to hydrazine derivatives were designed and synthesized. These new ILs as bipropellant fuels, have some unique advantages including negligible vapor pressure, ultra-short ignition delay (ID) time, and reduced synthetic and storage costs, thereby showing great application potential as environmentally friendly fuels in bipropellant formulations. PMID:24737218

Zhang, Qinghua; Yin, Ping; Zhang, Jiaheng; Shreeve, Jean'ne M

2014-06-01

314

Stable prenucleation mineral clusters are liquid-like ionic polymers  

PubMed Central

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.

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

2011-01-01

315

Theoretical study of cellobiose hydrolysis to glucose in ionic liquids  

NASA Astrophysics Data System (ADS)

The SN1-type hydrolysis reaction of cellobiose in ionic liquids (ILs) was theoretically investigated. First principles and ab initio quantum chemical methods were used in conjunction with the ‘reference interaction site model self-consistent field with spatial electron density distribution’ (RISM-SCF-SEDD) method. Reaction mechanism pathways are discussed and compared to calculations in gas phase and in aqueous solution. Analysis of solvation effects indicates strong interaction between hydrogen atoms of glucose hydroxyl groups and the anions in ILs, contributing to large stabilization of the reaction product. The calculated activation energy in ILs (24.5 kcal/mol) agrees quantitatively with the experimental value (26.5 kcal/mol).

Nishimura, Yoshifumi; Yokogawa, Daisuke; Irle, Stephan

2014-05-01

316

Thermogravimetric analysis of lignocellulosic biomass with ionic liquid pretreatment.  

PubMed

Thermogravimetry (TG) was employed to understand the interactions between ionic liquids (ILs) and biomass components. The thermal decomposition profiles of several biomass samples with IL pretreatment at different temperatures were studied by TG. Samples of Avicel (PH101), xylan from beechwood and alkaline lignin as well as switchgrass and corn stover were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. Analysis of TG data provided insight into the mode of degradation of xylan and lignin in [C4mim][OAc]. Pretreated Avicel samples exhibited higher decomposition temperatures due to transformation from cellulose I into cellulose II, while samples of switchgrass and corn stover showed an improved thermal stability as a result of removal of minerals by [C4mim][OAc]. More intensive pretreatment produced decreased thermal resistance due to degradation of biomass components and decrystallization. PMID:24365118

Zhang, Jiafu; Feng, Lu; Wang, Dan; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

2014-02-01

317

Testing Fundamental Properties of Ionic Liquids for Colloid Microthruster Applications  

NASA Technical Reports Server (NTRS)

NASA's New Millennium Program is scheduled to test a Disturbance Reduction System (DRS) on Space Technology 7 (ST7) as part of the European Space Agency's (ESA's) LISA Pathfinder Mission in late 2009. Colloid Micronewton Thrusters (CMNTs) will be used to counteract forces, mainly solar photon pressure, that could disturb gravitational reference sensors as part of the DRS. The micronewton thrusters use an ionic liquid, a room temperature molten salt, as propellant. The ionic liquid has a number of unusual properties that have a direct impact on thruster design. One of the most important issues is bubble formation before and during operation, especially during rapid pressure transitions from atmospheric to vacuum conditions. Bubbles have been observed in the feed system causing variations in propellant flow rate that can adversely affect thruster control. Bubbles in the feed system can also increase the likelihood that propellant will spray onto surfaces that can eventually lead to shorting high voltage electrodes. Two approaches, reducing the probability of bubble formation and removing bubbles with a new bubble eliminator device in the flow system, were investigated at Busek Co., Inc. and the Jet Propulsion Laboratory (JPL) to determine the effectiveness of both approaches. Results show that bubble formation is mainly caused by operation at low pressure and volatile contaminants in the propellant coming out of solution. A specification for the maximum tolerable level of contamination has been developed, and procedures for providing system cleanliness have been tested and implemented. The bubble eliminator device has also been tested successfully and has been implemented in recent thruster designs at Busek. This paper focuses on the propellant testing work at JPL, including testing of a breadboard level bubble eliminator device.

Anderson, John R.; Plett, Gary; Anderson, Mark; Ziemer, John

2006-01-01

318

Evaluation of four ionic liquids for pretreatment of lignocellulosic biomass  

PubMed Central

Background Lignocellulosic biomass is highly recalcitrant and various pretreatment techniques are needed to facilitate its effective enzymatic hydrolysis to produce sugars for further conversion to bio-based chemicals. Ionic liquids (ILs) are of interest in pretreatment because of their potential to dissolve lignocellulosic materials including crystalline cellulose. Results Four imidazolium-based ionic liquids (ILs) ([C=C2C1im][MeCO2], [C4C1im][MeCO2], [C4C1im][Cl], and [C4C1im][HSO4]) well known for their capability to dissolve lignocellulosic species were synthesized and then used for pretreatment of substrates prior to enzymatic hydrolysis. In order to achieve a broad evaluation, seven cellulosic, hemicellulosic and lignocellulosic substrates, crystalline as well as amorphous, were selected. The lignocellulosic substrates included hybrid aspen and Norway spruce. The monosaccharides in the enzymatic hydrolysate were determined using high-performance anion-exchange chromatography. The best results, as judged by the saccharification efficiency, were achieved with [C4C1im][Cl] for cellulosic substrates and with the acetate-based ILs for hybrid aspen and Norway spruce. After pretreatment with acetate-based ILs, the conversion to glucose of glucan in recalcitrant softwood lignocellulose reached similar levels as obtained with pure crystalline and amorphous cellulosic substrates. IL pretreatment of lignocellulose resulted in sugar yields comparable with that obtained with acidic pretreatment. Heterogeneous dissolution with [C4C1im][HSO4] gave promising results with aspen, the less recalcitrant of the two types of lignocellulose included in the investigation. Conclusions The ability of ILs to dissolve lignocellulosic biomass under gentle conditions and with little or no by-product formation contributes to making them highly interesting alternatives for pretreatment in processes where high product yields are of critical importance.

2014-01-01

319

Low viscous and highly conductive phosphonium ionic liquids based on bis(fluorosulfonyl)amide anion as potential electrolytes  

Microsoft Academic Search

The physical and electrochemical properties of room-temperature ionic liquids based on quaternary phosphonium cations together with a bis(fluorosulfonyl)amide anion are presented in this report. The bis(fluorosulfonyl)amide-based phosphonium ionic liquids were relatively low-melting, low viscous and highly conductive when compared to those of the corresponding bis(trifluoromethylsulfonyl)amide-based ionic liquids. Particularly, the ionic liquids containing a methoxy group in the phosphonium cations indicated

Katsuhiko Tsunashima; Atsuko Kawabata; Masahiko Matsumiya; Shun Kodama; Ryuichi Enomoto; Masashi Sugiya; Yoshihito Kunugi

2011-01-01

320

Using Monte Carlo simulation to compute liquid-vapor saturation properties of ionic liquids.  

PubMed

We discuss Monte Carlo (MC) simulation methods for calculating liquid-vapor saturation properties of ionic liquids. We first describe how various simulation tools, including reservoir grand canonical MC, growth-expanded ensemble MC, distance-biasing, and aggregation-volume-biasing, are used to address challenges commonly encountered in simulating realistic models of ionic liquids. We then indicate how these techniques are combined with histogram-based schemes for determining saturation properties. Both direct methods, which enable one to locate saturation points at a given temperature, and temperature expanded ensemble methods, which provide a means to trace saturation lines to low temperature, are discussed. We study the liquid-vapor phase behavior of the restricted primitive model (RPM) and a realistic model for 1,3-dimethylimidazolium tetrafluoroborate ([C1mim][BF4]). Results are presented to show the dependence of saturation properties of the RPM and [C1mim][BF4] on the size of the simulation box and the boundary condition used for the Ewald summation. For [C1mim][BF4] we also demonstrate the ability of our strategy to sample ion clusters that form in the vapor phase. Finally, we provide the liquid-vapor saturation properties of these models over a wide range of temperature. Overall, we observe that the choice of system size and boundary condition have a non-negligible effect on the calculated properties, especially at high temperature. Also, we find that the combination of grand canonical MC simulation and isothermal-isobaric temperature expanded ensemble MC simulation provides a computationally efficient means to calculate liquid-vapor saturation properties of ionic liquids. PMID:23734733

Rane, Kaustubh S; Errington, Jeffrey R

2013-07-01

321

Characterization of PVdF(HFP) gel electrolytes based on 1-(2-Hydroxyethyl)-3-methyl imidazolium ionic liquids.  

PubMed

Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared using ionic liquids based on 1-(2-hydroxyethyl)-3-methyl imidazolium tetrafluoroborate and 1-(2-hydroxyethyl)-3-methyl imidazolium hexafluorophosphate. A conventional metathesis reaction was used to prepare these ionic liquids, which have high purity and exhibit a liquid state at room temperature. The prepared polymer-ionic liquid gel proved to be a free-standing and rubbery film in which the degree of transparency differed according to the ratio and type of ionic liquid used. TGA and FTIR analyses confirmed that the solvent, N,N-Dimethylacetamide (DMAC), used for mixing PVdF(HFP) polymer with ionic liquid was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface structure of the PVdF(HFP)-ionic liquid gel in order to evaluate the morphology of the film's surface according to the mixing ratio and the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be similar to those of neat ionic liquids through DSC analysis, and the compatibility between the polymer and ionic liquid was investigated by XRD analysis. The ionic conductivities of all the gels were 10(-3)-10(-5) S cm(-1) in a temperature range of 20-70 degrees C. PMID:16853301

Yeon, Sun-Hwa; Kim, Ki-Sub; Choi, Sukjeong; Cha, Jong-Ho; Lee, Huen

2005-09-29

322

The observation of dianions generated by electrochemical reduction of trans-stilbenes in ionic liquids at room temperature.  

PubMed

Three highly aprotic bis(trifluoromethylsulfonyl)amide (NTf2(-)) based ionic liquids (ILs) containing the cations trihexyl(tetradecyl)phosphonium (P6,6,6,14(+)), N-butyl-N-methylpyrrolidinium (Pyrr4,1(+)), and (trimethylamine)(dimethylethylammine)dihydroborate ((N111)(N112)BH2(+)) have been examined as media for room temperature voltammetric detection of highly basic stilbene dianions electrochemically generated by the reduction of trans-stilbene (t-Stb) and its derivatives (4-methoxy-, 2-methoxy-, 4,4'-dimethyl-, and 4-chloromethyl-). Transient and steady-state data in the ILs were compared with results obtained in the molecular solvent acetonitrile. In all media examined, the t-Stb(0/•-) process is chemically and electrochemically reversible with a heterogeneous charge transfer rate constant in CH3CN of 1.5 cm s(-1), as determined by Fourier transformed AC voltammetry. However, further reduction to the dianion was always irreversible in this molecular but weakly acidic solvent. On the other hand, a substantial level of chemical reversibility for the reduction of t-Stb(•-) to t-Stb(2-) on the time scale of cyclic voltammetry is achieved when the concentration of trans-stilbene, [t-Stb], appreciably exceeds the concentration of adventitious water or other proton sources. In particular, these conditions are met when [t-Stb] ? 0.1 M in thoroughly dehydrated and purified ILs, while in the presence of CH3CN, t-Stb(2-) still suffers fast irreversible protonation under these stilbene concentration conditions. The E0/•-(0) values (vs Fc(0/+)) for substituted trans-stilbenes in acetonitrile and (N111)(N112)BH2-NTf2 do not differ substantially, nor do the E0/•-(0) and E•-/2-(0) differences or other aspects of the voltammetric behavior. PMID:23659207

Abdul-Rahim, Omar; Simonov, Alexandr N; Rüther, Thomas; Boas, John F; Torriero, Angel A J; Collins, David J; Perlmutter, Patrick; Bond, Alan M

2013-06-18

323

Conductivity Scaling Relationships for Nanostructured Block Copolymer/Ionic Liquid Membranes  

NASA Astrophysics Data System (ADS)

Nanostructured membranes containing structural and ion-conducting domains are of great interest for a wide range of applications requiring high conductivity coupled with high thermal stability. To optimize the properties of such membranes, it is essential to understand scaling relationships between composition, structure, temperature, and ionic conductivity. The conductivity behaviors of mixtures of two block copolymer chemistries with two different ionic liquids have been investigated. The conductivities of all the mixtures are described by a single expression, which combines the Vogel-Tamman-Fulcher (VTF) equation with percolation theory. The VTF equation takes into account the effect of the glass transition temperature of the conducting phase on the temperature dependence of conductivity, while percolation theory reflects the power law dependence of conductivity on the overall volume fraction of ionic liquid in the membrane. The dominance of the overall volume fraction of ionic liquid in determining conductivity indicates that there is incredible flexibility in designing highly conductive block copolymer/ionic liquid membranes.

Hoarfrost, Megan; Segalman, Rachel

2013-03-01

324

Stabilizing nanoparticle catalysts in imidazolium-based ionic liquids: A comparative study  

Microsoft Academic Search

Room temperature imidazolium-based ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) have been used as effective liquid media for the synthesis of pure Au and bimetallic PdAu nanoparticles by direct synthesis and phase-transfer methods. The mode-of-stability, long-term stability, and long lifetimes of these ionic-liquid supported nanoparticle catalysts, all of which are important factors in determining the overall “greenness” of such materials,

Priyabrat Dash; Sarah M. Miller; Robert W. J. Scott

2010-01-01

325

Densities and isothermal compressibilities of ionic liquids—Modeling and application  

Microsoft Academic Search

Two corresponding-states forms have been developed for direct correlation function integrals in liquids to represent pressure effects on the volume of ionic liquids over wide ranges of temperature and pressure. The correlations can be analytically integrated from a chosen reference density to provide a full equation of state for ionic liquids over reduced densities from 1.5 to more than 3.6.

Jens Abildskov; Martin D. Ellegaard; John P. O’Connell

2010-01-01

326

Ion insertion into ionic liquid supported toluene generated by electrochemical redox reaction  

Microsoft Academic Search

Ion transfer across the toluene|water, toluene–ionic liquid mixture|water and ionic liquid|water boundary generated by electrochemical redox reaction of tert-butylferrocene (tBuFc) was studied with the glassy carbon (GC) electrode partially covered by the organic liquid deposit and immersed in the aqueous electrolyte solution. The electrooxidation of the redox probe in toluene deposit is followed by ejection of newly formed cation into

Galyna Shul; Wojciech Adamiak; Marcin Opallo

2008-01-01

327

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

328

Reverse dynamic calorimetry of a viscous ionic liquid.  

PubMed

We compare the time scale of thermal relaxation with that of the electric modulus in the deeply supercooled regime of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. Thermal relaxation refers to the process of configurational temperatures of the slow degrees of freedom equilibrating toward the vibrational temperature, which is a reliable indicator for the time scale of structural relaxation. Energy is supplied to the sample by absorption from a sinusoidal electric field with amplitude as high as 387 kV/cm and frequencies in the 0.2 Hz-56 kHz range, analogous to microwave heating. The time resolved response of configurational temperature as well as the low field dielectric properties are measured in a single high field impedance setup. Near T(g), we find that the macroscopic field (or modulus M) relaxes considerably faster than the structure (in terms of thermal relaxation, solvation dynamics, and probe rotation), although the liquid is entirely composed of mobile ions. PMID:19916606

Huang, Wei; Richert, Ranko

2009-11-14

329

Micellization of sodium laurylethoxysulfate (SLES) and short chain imidazolium ionic liquids in aqueous solution.  

PubMed

In the present study the interactions between an anionic surfactant sodium laurylethoxysulfate (SLES) and three short chain imidazolium (1-butyl-3-methylimidazolium) based ionic liquids (bmim-octyl SO4, bmim-methyl SO4 and bmim-BF4) in aqueous solution have been investigated. Generally when a surfactant is dissolved in a hydrophilic ionic liquid aqueous solution the critical micelle concentration (cmc) obtained is attributed to the surfactant because the ionic liquid (IL) is considered to be only a cosolvent. However, some short hydrophilic ionic liquids posses surface activity in aqueous solution and behave like a surfactant. In that case mixed aggregates between surfactant and ionic liquid can be formed. The three SLES/IL systems here studied have been treated as typical binary surfactant mixtures in aqueous solution. Surface tension measurements have revealed that mixed aggregates and monolayers of surfactant and ionic liquid instead of single surfactant are responsible for the surface active properties of these aqueous solutions. From the Regular Solution Theory, negative interaction parameters (?) for mixed aggregates and monolayers have been found for all SLES/IL mole ratios indicating synergism between the anionic surfactant and the ionic liquids. PMID:24776662

Comelles, Francesc; Ribosa, Isabel; González, Juan José; Garcia, M Teresa

2014-07-01

330

Ordering of Triblock Copolymer Surfactants by Blending with a Room Temperature Ionic Liquid  

NASA Astrophysics Data System (ADS)

Well-ordered block copolymer morphologies were obtained by blending Pluronic PEO-PPO-PEO triblock copolymer surfactants with the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. The selective association of the ionic liquid with the PEO blocks raises the effective interaction parameter between the PEO and PPO blocks. Therefore, the copolymer/ionic liquid blends form well-ordered microdomains in the melt, whereas the neat copolymers are phase mixed in the melt. The ionic liquid was confirmed to interact with the PEO chains by a depression in the melting point of the PEO crystals with increasing ionic liquid concentration. Wide angle x-ray scattering and polarized optical microscopy also indicate disruption of PEO crystallization in the blends. Infrared spectroscopy also indicates a strong interaction between the PEO blocks and ionic liquid. The formation of well-ordered microdomains is demonstrated by small angle x-ray scattering experiments, which show the appearance of higher order peaks with increasing ionic liquid concentration.

Miranda, Daniel; Watkins, James; Russell, Thomas

2010-03-01

331

Interaction of ionic liquids ions with natural cyclodextrins.  

PubMed

The interaction of natural ?-, ?-, and ?-cyclodextrins (CDs) with 14 hydrophobic ionic moieties of ionic liquids (ILs) was systematically examined in dilute aqueous solutions using isothermal titration microcalorimetry (ITC) and NMR spectroscopy. The studied cationic and anionic moieties involved some recently developed heavily fluorinated structures, as well as some others of common use. To isolate the effect of a given ion, the measurements were performed on salts containing the hydrophobic IL ion in question and a complexation-inactive counterion. Additional ITC experiments on ILs whose both cation and anion can interact appreciably with the CD cavity demonstrated that to resolve the effect of individual ions from such data is generally a tricky task and confirmed the superiority of the isolation strategy adopted for the purpose throughout this work. The binding constant, enthalpy and entropy determined at 298.15 K for the 1:1 (ion:CD) inclusion complex formation range in broad limits, being 0 < K < 2 × 10(5), 0 < -?(r)H°/(kJ·mol(-1)) < 44, and -28 < T?(r)S°/(kJ·mol(-1)) < 14, respectively. The stabilities of complexes of perfluorohexyl bearing ions with ?-CD belong to the highest ever observed with natural CDs in water. The established binding affinity scales were discussed in both thermodynamic and molecular terms. The concepts of hydrophobic interaction and guest-host size matching supported by simple molecular modeling proved useful to rationalize the observed widely different binding affinities and suggest possible binding modes. Enthalpy and entropy contributions to the stability of the ion-CD complexes were found to compensate each other considerably obeying more or less the linear compensation relationship marked by existing literature data on binding other guests to natural CDs. As outliers to this pattern, the most stable complexes of -C(6)F(13) bearing ions with ?-CD were found to receive an enhanced inherent entropy stabilization due to extraordinarily high extent of desolvation occurring in the course of binding. PMID:21786823

Ondo, Daniel; Tkadlecová, Marcela; Dohnal, Vladimír; Rak, Jakub; Kví?ala, Jaroslav; Lehmann, Jochen K; Heintz, Andreas; Ignatiev, Nikolai

2011-09-01

332

On the collective network of ionic liquid/water mixtures. IV. Kinetic and rotational depolarization.  

PubMed

Dielectric spectroscopy is a measure of the collective Coulomb interaction in liquid systems. Adding ionic liquids to an aqueous solution results in a decrease of the static value of the generalized dielectric constant which cannot be attributed to kinetic depolarization models characterized by the static conductivity and rotational relaxation constant. However, a dipolar Poisson-Boltzmann model computing the water depolarization in the proximity of ions is not only successful for simple electrolytes but also in case of molecular ionic liquids. Moreover, our simple geometric hydration model is also capable to explain the dielectric depolarization. Both models compute the dielectric constant of water and obtain the overall dielectric constant by averaging the values of its components, water and the ionic liquid, weighted by their volume occupancies. In this sense, aqueous ionic liquid mixtures seem to behave like polar mixtures. PMID:24880299

Schröder, Christian; Sega, Marcello; Schmollngruber, Michael; Gailberger, Elias; Braun, Daniel; Steinhauser, Othmar

2014-05-28

333

Structure of tetraalkylammonium ionic liquids in the interlayer of modified montmorillonite.  

PubMed

We perform molecular dynamics simulations of tetraalkylammonium ionic liquids confined in the interlayer of montmorillonite (MMT). We study the structure and energetics of the systems, which consist of cations with two different alkyl chain lengths and several ionic liquid concentrations. The results we obtained for the structure, namely the presence of a strong layering in all systems and the formation of nonpolar domains with interdigitated alkyl chains in some cases, are largely consistent with previous surface force balance experiments performed on similar systems. Finally, we show that swelling of the organo-modified MMT by a large amount of ionic liquid seems energetically favorable in all cases. PMID:24920411

Duarte, Daniel; Salanne, Mathieu; Rotenberg, Benjamin; Bizeto, Marcos A; Siqueira, Leonardo J A

2014-07-16

334

Formation of p-n-p junction with ionic liquid gate in graphene  

NASA Astrophysics Data System (ADS)

Ionic liquid gating is a technique which is much more efficient than solid gating to tune carrier density. To observe the electronic properties of such a highly doped graphene device, a top gate made of ionic liquid has been used. By sweeping both the top and back gate voltage, a p-n-p junction has been created. The mechanism of forming the p-n-p junction has been discussed. Tuning the carrier density by ionic liquid gate can be an efficient method to be used in flexible electronics.

He, Xin; Tang, Ning; Gao, Li; Duan, Junxi; Zhang, Yuewei; Lu, Fangchao; Xu, Fujun; Wang, Xinqiang; Yang, Xuelin; Ge, Weikun; Shen, Bo

2014-04-01

335

Direct Enzymatic Oxidation of Glucose with a Poly(Ionic Liquid) - Gold-Nanoparticle Composite  

NASA Astrophysics Data System (ADS)

In this work we describe the synthesis, fabrication and characterization of a gold nanoparticle - ionic liquid-derived polymer composite for conversion of biofuels into electricity. Glucose oxidase (GOx) electrostatically adsorbed on an ionic liquid-derived polymer containing internally organized columns of Au nanoparticles exhibits bioelectrocatalytic properties in the oxidation of glucose. The cationic poly(ionic liquid) provides an ideal substrate for the immobilization of GOx. The encapsulated Au nanoparticles serve two roles: promoting direct electron transfer with the recessed enzyme redox centers, and imparting electronic conduction to the composite, thereby allowing it to function as an electrode for electrochemical detection.

Firestone, Millicent; Lee, Sungwon; Seifert, Soenke

2011-03-01

336

Structure of tetraalkylammonium ionic liquids in the interlayer of modified montmorillonite  

NASA Astrophysics Data System (ADS)

We perform molecular dynamics simulations of tetraalkylammonium ionic liquids confined in the interlayer of montmorillonite (MMT). We study the structure and energetics of the systems, which consist of cations with two different alkyl chain lengths and several ionic liquid concentrations. The results we obtained for the structure, namely the presence of a strong layering in all systems and the formation of nonpolar domains with interdigitated alkyl chains in some cases, are largely consistent with previous surface force balance experiments performed on similar systems. Finally, we show that swelling of the organo-modified MMT by a large amount of ionic liquid seems energetically favorable in all cases.

Duarte, Daniel; Salanne, Mathieu; Rotenberg, Benjamin; Bizeto, Marcos A.; Siqueira, Leonardo J. A.

2014-07-01

337

Protic ionic liquid as additive on lipase immobilization using silica sol-gel.  

PubMed

Ionic liquids (ILs) have evolved as a new type of non-aqueous solvents for biocatalysis, mainly due to their unique and tunable physical properties. A number of recent review papers have described a variety of enzymatic reactions conducted in IL solutions, on the other hand, to improve the enzyme's activity and stability in ILs; major methods being explored include the enzyme immobilization (on solid support, sol-gel, etc.), protic ionic liquids used as an additive process. The immobilization of the lipase from Burkholderia cepacia by the sol-gel technique using protic ionic liquids (PIL) as additives to protect against inactivation of the lipase due to release of alcohol and shrinkage of the gel during the sol-gel process was investigated in this study. The in?uence of various factors such as the length of the alkyl chain of protic ionic liquids (monoethanolamine-based) and a concentration range between 0.5 and 3.0% (w/v) were evaluated. The resulting hydrophobic matrices and immobilized lipases were characterised with regard to specific surface area, adsorption-desorption isotherms, pore volume (V(p)) and size (d(p)) according to nitrogen adsorption and scanning electron microscopy (SEM), physico-chemical properties (thermogravimetric - TG, differential scanning calorimetry - DSC and Fourier transform infrared spectroscopy - FTIR) and the potential for ethyl ester and emulsifier production. The total activity yields (Y(a)) for matrices of immobilized lipase employing protic ionic liquids as additives always resulted in higher values compared with the sample absent the protic ionic liquids, which represents 35-fold increase in recovery of enzymatic activity using the more hydrophobic protic ionic liquids. Compared with arrays of the immobilized biocatalyst without additive, in general, the immobilized biocatalyst in the presence of protic ionic liquids showed increased values of surface area (143-245 m(2) g(-1)) and pore size (19-38 Å). Immobilization with protic ionic liquids also favoured reduced mass loss according to TG curves (always less than 42.9%) when compared to the immobilized matrix without protic ionic liquids (45.1%), except for the sample containing 3.0% protic ionic liquids (46.5%), verified by thermogravimetric analysis. Ionic liquids containing a more hydrophobic alkyl group in the cationic moiety were beneficial for recovery of the activity of the immobilized lipase. The physico-chemical characterization confirmed the presence of the enzyme and its immobilized derivatives obtained in this study by identifying the presence of amino groups, and profiling enthalpy changes of mass loss. PMID:23410924

de Souza, Ranyere Lucena; de Faria, Emanuelle Lima Pache; Figueiredo, Renan Tavares; Freitas, Lisiane dos Santos; Iglesias, Miguel; Mattedi, Silvana; Zanin, Gisella Maria; dos Santos, Onélia Aparecida Andreo; Coutinho, João A P; Lima, Álvaro Silva; Soares, Cleide Mara Faria

2013-03-01

338

Ionic liquid–polymer gel electrolytes based on morpholinium salt and PVdF(HFP) copolymer  

Microsoft Academic Search

New ionic liquid–polymer gel electrolytes (IPGEs) are prepared from N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (Mor1,2TFSI) and poly(vinylidene fluoride)-hexafluoropropylene copolymer (PVdF(HFP)). To investigate the effect of propylene carbonate (PC) on the ionic conductivity of the IPGEs, the preparation methods are roughly divided into two groups according to the presence or absence of PC. The ionic conductivity for each IPGE is measured with increasing temperature

Ki-Sub Kim; Seung-Yeob Park; Sukjeong Choi; Huen Lee

2006-01-01

339

Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends  

PubMed Central

Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P13TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more “conventional” rechargeable lithium and lithium ion batteries.

Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

2009-01-01

340

Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends.  

PubMed

Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P(13)TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P(13)TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more "conventional" rechargeable lithium and lithium ion batteries. PMID:20354587

Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G

2007-09-21

341

Application of ultrasound-assisted ionic liquid dispersive liquid-phase microextraction followed high-performance liquid chromatography for the determination of fungicides in red wine  

Microsoft Academic Search

A new method was developed for the determination of fungicides in red wine using ultrasound-assisted ionic liquid dispersive\\u000a liquid–phase microextraction followed by high-performance liquid chromatography. The ionic liquid, 1-hexyl-3-methylimidazolium\\u000a hexafluorophosphate (IL) was quickly disrupted by ultrasonication and dispersed in wine as fine droplets. At this stage, the\\u000a analytes were extracted into the fine droplets of IL. After centrifugation, the concentration

Suli Wang; Liping Ren; Yanjun Xu; Fengmao Liu

2011-01-01

342

Effect of stationary phase polarity on the retention of ionic liquid cations in reversed phase liquid chromatography.  

PubMed

Chromatographic analysis of ionic liquids on different types of packings offers interesting possibility to determine their retention mechanism. As a consequence, the major interactions between stationary phase ligands and analyzed chemical entities can be defined. The main aim of this work was to analyze cations of ionic liquids on chemically bonded stationary phases with specific structural properties. The attempt to predict the main interactions between positive ions of ionic liquids and stationary phase ligands was undertaken. For that purpose, butyl, octyl, octadecyl, phenyl, aryl, mixed, alkylamide, and cholesterolic packings were chosen and applied to the analysis of six most commonly used ionic liquids' cations. Obtained results indicate mainly dispersive and pi-pi type of interaction part in the retention mechanism of analyzed compounds. PMID:17313103

Kowalska, Sylwia; Buszewski, Boguslaw

2006-11-01

343

Synthesis of new solid polymer electrolyte and actuator based on PEDOT\\/NBR\\/ionic liquid  

Microsoft Academic Search

The conducting polymer actuator was presented. The solid polymer electrolyte based on nitrile rubber (NBR) activated with different ionic liquids was prepared. The three different grades of NBR films were synthesized by emulsion polymerization with different amount of acrylonitrile, 23, 35, and 40 mol. %, respectively. The effect of acrylonitrile content on the ionic conductivity and dielectric constant of solid

M. S. Cho; H. J. Seo; J. D. Nam; H. R. Choi; J. C. Koo; Y. Lee

2006-01-01

344

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

345

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

2013-07-01

346

Proactive aquatic ecotoxicological assessment of room-temperature ionic liquids  

USGS Publications Warehouse

Aquatic environments are being contaminated with a myriad of anthropogenic chemicals, a problem likely to continue due to both unintentional and intentional releases. To protect valuable natural resources, novel chemicals should be shown to be environmentally safe prior to use and potential release into the environment. Such proactive assessment is currently being applied to room-temperature ionic liquids (ILs). Because most ILs are water-soluble, their effects are likely to manifest in aquatic ecosystems. Information on the impacts of ILs on numerous aquatic organisms, focused primarily on acute LC50 and EC50 endpoints, is now available, and trends in toxicity are emerging. Cation structure tends to influence IL toxicity more so than anion structure, and within a cation class, the length of alkyl chain substituents is positively correlated with toxicity. While the effects of ILs on several aquatic organisms have been studied, the challenge for aquatic toxicology is now to predict the effects of ILs in complex natural environments that often include diverse mixtures of organisms, abiotic conditions, and additional stressors. To make robust predictions about ILs will require coupling of ecologically realistic laboratory and field experiments with standard toxicity bioassays and models. Such assessments would likely discourage the development of especially toxic ILs while shifting focus to those that are more environmentally benign. Understanding the broader ecological effects of emerging chemicals, incorporating that information into predictive models, and conveying the conclusions to those who develop, regulate, and use those chemicals, should help avoid future environmental degradation. ?? 2011 Bentham Science Publishers Ltd.

Kulacki, K. J.; Chaloner, D. T.; Larson, J. H.; Costello, D. M.; Evans-White, M. A.; Docherty, K. M.; Bernot, R. J.; Brueseke, M. A.; Kulpa, C. F.; Lamberti, G. A.

2011-01-01

347

Impact of high biomass loading on ionic liquid pretreatment  

PubMed Central

Background Ionic liquid (IL) pretreatment has shown great potential as a novel pretreatment technology with high sugar yields. To improve process economics of pretreatment, higher biomass loading is desirable. The goal of this work is to establish, the impact of high biomass loading of switchgrass on IL pretreatment in terms of viscosity, cellulose crystallinity, chemical composition, saccharification kinetics, and sugar yield. Results The pretreated switchgrass/IL slurries show frequency dependent shear thinning behavior. The switchgrass/IL slurries show a crossover from viscous behavior at 3?wt% to elastic behavior at 10?wt%. The relative glucan content of the recovered solid samples is observed to decrease with increasing levels of lignin and hemicelluloses with increased biomass loading. The IL pretreatment led to a transformation of cellulose crystalline structure from I to II for 3, 10, 20 and 30?wt% samples, while a mostly amorphous structure was found for 40 and 50?wt% samples. Conclusions IL pretreatment effectively reduced the biomass recalcitrance at loadings as high as 50?wt%. Increased shear viscosity and a transition from ‘fluid’ like to ‘solid’ like behavior was observed with increased biomass loading. At high biomass loadings shear stress produced shear thinning behavior and a reduction in viscosity by two orders of magnitude, thereby reducing the complex viscosity to values similar to lower loadings. The rheological properties and sugar yields indicate that 10 to 50?wt% may be a reasonable and desirable target for IL pretreatment under certain operating conditions.

2013-01-01

348

Protic ionic liquids and salts as versatile carbon precursors.  

PubMed

Instead of traditional polymer precursors and complex procedures, easily prepared and widely obtainable nitrogen-containing protic ionic liquids and salts were explored as novel, small-molecule precursors to prepare carbon materials (CMs) via direct carbonization without other treatments. Depending on the precursor structure, the resultant CMs can be readily obtained with a relative yield of up to 95.3%, a high specific surface area of up to 1380 m(2)/g, or a high N content of up to 11.1 wt%, as well as a high degree of graphitization and high conductivity (even higher than that of graphite). One of the carbons, which possesses a high surface area and a high content of pyridinic N, exhibits excellent electrocatalytic activity toward the oxygen reduction reaction in an alkaline medium, as revealed by an onset potential, half-wave potential, and kinetic current density comparable to those of commercial 20 wt% Pt/C. These low-cost and versatile precursors are expected to be important building blocks for CMs. PMID:24450770

Zhang, Shiguo; Miran, Muhammed Shah; Ikoma, Ai; Dokko, Kaoru; Watanabe, Masayoshi

2014-02-01

349

Conventional Study on Novel Dicationic Ionic Liquid Inclusion with ?-Cyclodextrin  

PubMed Central

This study focuses on the synthesis and characterization of the inclusion complex of ?-Cyclodextrin (?-CD) with dicationic ionic liquid, 3,3?-(1,4-Phenylenebis [methylene]) bis(1-methyl-1H-imidazol-3-ium) di(bromide) (PhenmimBr). The inclusion complex was prepared at room temperature utilizing conventional kneading technique. Proton (1H) NMR and 2D (1H–1H) COSY NMR were the primary characterization tools employed to verify the formation of the inclusion complex. COSY spectra showed strong correlations between protons of imidazolium and protons of ?-CD which indicates that the imidazolium ring of PhenmimBr has entered the cavity of ?-CD. UV absorption indicated that ?-CD reacts with PhenmimBr to form a 2:1 ?-CD-PhenmimBr complex with an apparent formation constant of 2.61 × 105 mol&?2 L2. Other characterization studies such as UV, FT-IR, XRD, TGA, DSC and SEM studies were also used to further support the formation of the ?-CD-PhenmimBr inclusion complex.

Mohamad, Sharifah; Surikumaran, Hemavathy; Raoov, Muggundha; Marimuthu, Tilagam; Chandrasekaram, Kumuthini; Subramaniam, Puvaneswary

2011-01-01

350

Terrestrial ecotoxicity of short aliphatic protic ionic liquids.  

PubMed

A study of the ecotoxicity of different short aliphatic protic ionic liquids (PILs) on terrestrial organisms was conducted. Tests performed within the present study include those assessing the effects of PILs on soil microbial functions (carbon and nitrogen mineralization) and terrestrial plants. The results show that the nominal lowest-observed-adverse-effect concentration (LOAEC) values were 5,000 mg/kg (dry soil) for the plant test in two species (Lolium perenne, Allium cepa), 1,000 mg/kg (dry soil) for the plant test in one species (Raphanus sativus), and 10,000 mg/kg (dry soil) for carbon and nitrogen microbial transformation tests (all concentrations are nominal). Most of the median effective concentration values (EC50) were above 1,000 mg/kg (dry soil). Based on the obtained results, these compounds can be described as nontoxic for soil microbiota and the analyzed plants, and potentially biodegradable in soils, as can be deduced from the respirometric experiment. The toxicity rises with the increase of complexity of the PILs molecule (branch and length of aliphatic chain) among the three PILs analyzed. PMID:21935980

Peric, Brezana; Martí, Esther; Sierra, Jordi; Cruañas, Robert; Iglesias, Miguel; Garau, Maria Antonia

2011-12-01

351

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

352

Enhanced performance of dicationic ionic liquid electrolytes by organic solvents  

NASA Astrophysics Data System (ADS)

The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance–electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation.

Li, Song; Zhang, Pengfei; Fulvio Pasquale, F.; Hillesheim Patrick, C.; Feng, Guang; Dai, Sheng; Cummings Peter, T.

2014-07-01

353

Thinning of reverse osmosis membranes by ionic liquids  

NASA Astrophysics Data System (ADS)

In this study, ionic liquids (ILs) were used to thin out the dense layer and, in turn, tune the surface properties and separation performance of commercial aromatic polyamide reverse osmosis membranes. It was observed that the structure of the ILs and dipping time had a strong impact on the dense layer thickness and morphology. This can be understood in terms of the dissolubility and interaction force between ILs and the organic membrane surface, such as hydrogen bonding and ?-? interactions. Among the ILs synthesized, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) showed the most promising thinning effects. It was observed that the thickness of the dense layer on the surface decreased from 127 to 67 nm after dipping treatment with [BMIM]Cl for 24 h. The water flux was enhanced by 20% at the expense of a slight decline of salt rejection. AFM, contact angle and zeta potential analyses suggest that the surface hydrophilicity and electronegativity increased, while the roughness decreased, which improved the anti-fouling properties.

Meng, Hong; Gong, Beibei; Geng, Tao; Li, Chunxi

2014-02-01

354

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

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

2013-08-21

355

Catalytic conversion of cellulose to chemicals in ionic liquid.  

PubMed

A simple and effective route for the production of 5-hydroxymethyl furfural (HMF) and furfural from microcrystalline cellulose (MCC) has been developed. CoSO(4) in an ionic liquid, 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate (IL-1), was found to be an efficient catalyst for the hydrolysis of cellulose at 150°C, which led to 84% conversion of MCC after 300min reaction time. In the presence of a catalytic amount of CoSO(4), the yields of HMF and furfural were up to 24% and 17%, respectively; a small amount of levulinic acid (LA) and reducing sugars (8% and 4%, respectively) were also generated. Dimers of furan compounds were detected as the main by-products through HPLC-MS, and with the help of mass spectrometric analysis, the components of gas products were methane, ethane, CO, CO(2,) and H(2). A mechanism for the CoSO(4)-IL-1 hydrolysis system was proposed and IL-1 was recycled for the first time, which exhibited favorable catalytic activity over five repeated runs. This catalytic system may be valuable to facilitate energy-efficient and cost-effective conversion of biomass into biofuels and platform chemicals. PMID:21092940

Tao, Furong; Song, Huanling; Chou, Lingjun

2011-01-01

356

Mesophases in nearly 2D room-temperature ionic liquids.  

PubMed

Computer simulations of (i) a [C(12)mim][Tf(2)N] film of nanometric thickness squeezed at kbar pressure by a piecewise parabolic confining potential reveal a mesoscopic in-plane density and composition modulation reminiscent of mesophases seen in 3D samples of the same room-temperature ionic liquid (RTIL). Near 2D confinement, enforced by a high normal load, as well as relatively long aliphatic chains are strictly required for the mesophase formation, as confirmed by computations for two related systems made of (ii) the same [C(12)mim][Tf(2)N] adsorbed at a neutral solid surface and (iii) a shorter-chain RTIL ([C(4)mim][Tf(2)N]) trapped in the potential well of part i. No in-plane modulation is seen for ii and iii. In case ii, the optimal arrangement of charge and neutral tails is achieved by layering parallel to the surface, while, in case iii, weaker dispersion and packing interactions are unable to bring aliphatic tails together into mesoscopic islands, against overwhelming entropy and Coulomb forces. The onset of in-plane mesophases could greatly affect the properties of long-chain RTILs used as lubricants. PMID:19886615

Manini, N; Cesaratto, M; Del Pópolo, M G; Ballone, P

2009-11-26

357

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

2013-09-01

358

Enhanced performance of dicationic ionic liquid electrolytes by organic solvents.  

PubMed

The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance-electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation. PMID:24920237

Li, Song; Zhang, Pengfei; Fulvio Pasquale, F; Hillesheim Patrick, C; Feng, Guang; Dai, Sheng; Cummings Peter, T

2014-07-16

359

Methane interactions with polyaniline/butylmethylimidazolium camphorsulfonate ionic liquid composite.  

PubMed

In our previous report, a polyaniline (PAn) and ionic liquid butylmethylimidazolium camphorsulfonate (BMICS) composite was used as a methane sensing material which significantly increased the sensitivity for methane detection using quartz crystal microbalance (QCM) transducers. In this paper, we focus on the interactions within the PAn/BMICS composite and between the composite and methane. UV-vis and Fourier transform infrared (FTIR) spectroscopic results indicated that the anion of BMICS, camphorsulfonate, could form hydrogen bonds with the "nitrogen" sites of protic acid doped PAn. These hydrogen bonds align the camphorsulfonate anions in a comblike manner along the PAn backbone and therefore enhance the long-range pi-orbital conjugation of PAn. Methane molecules absorbed into the PAn/BMICS may sit in the "space" between the aligned anions and cations of BMICS. By measuring the methane absorption in PAn/BMICS at a temperature range of 25-65 degrees C, the entropy and enthalpy of dissolution were obtained following the van't Hoff equation. They are -163.2 +/- 30.1 J/mol.K and -50.5 +/- 8.7 kJ/mol, respectively, which are relatively higher than those in pure BMICS and in PAn only. These thermodynamic parameters further support that the absorbed methane molecules might exist in PAn/BMICS in a relatively ordered manner. Molecular mechanics simulation results agree with the spectroscopic and thermodynamic results. PMID:18817423

Yu, Lei; Jin, Xiaoxia; Zeng, Xiangqun

2008-10-21

360

Ether-Bond-Containing Ionic Liquids as Supercapacitor Electrolytes  

PubMed Central

Electrochemical capacitors (ECs) are electrical energy storage devices that have the potential to be very useful in a wide range of applications, especially where there is a large disparity between peak and average power demands. The use of ionic liquids (ILs) as electrolytes in ECs can increase the energy density of devices; however, the viscosity and conductivity of ILs adversely influence the power density of the device. We present experimental results where several ILs containing different cations have been employed as the electrolyte in cells containing mesoporous carbon electrodes. Specifically, the behavior of ILs containing an ether bond in an alkyl side chain are compared with those of a similar structure and size but containing purely alkyl side chains. Using electrochemical impedance spectroscopy and constant current cycling, we show that the presence of the ether bond can dramatically increase the specific capacitance and reduce device resistance. These results have the important implication that such ILs can be used to tailor the physical properties and electrochemical performance of IL-based electrolytes.

2013-01-01

361

Binding energies of CO2 with some ionic liquids  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (RTILs), a novel class of materials with negligible vapor pressures and potentiality as benign solvents, may be an ideal chemical for carbon dioxide (CO2) gas sequestration. Ab initio computational modeling was used to investigate the molecular interactions of simple RTIL anions hexafluorophosphate (PF6^-) and tetrafluoroborate (BF4^-) with CO2. Electronic potential energy surface (PES) scans of a comprehensive sampling of 1:1 anion-CO2 orientations were computed using Spartan '02 with Dunning's correlation consistent basis sets. Qualitatively, the PES scans yielded deeper, more numerous and radially closer active sites surrounding BF4^- anion as compared with the PF6^- anion. Quantitatively, the binding energies of 17.87 kJ/mol and 25.24 kJ/mol were extracted from the identified global energy minima for the PF6^- and BF4^- systems, respectively. The smaller BF4^- anion was concluded to bind more strongly to the CO2. However, literature-reported experimental Henry's law constants for CO2 dissolved in imidizolium based RTILs show greater gas solvation in the PF6^- system. The discrepancy between the energetics calculation results and the experimental solvation data will be discussed.

Eucker, William; Bendler, John

2007-03-01

362

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

363

Production and irradiation of ionic liquid cluster ions  

NASA Astrophysics Data System (ADS)

We have developed a field-emission-type of cluster ion source using ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). The current obtained was stable by placing a porous cap around the emitter. Time-of-flight (TOF) measurement showed that the peak mass number was approximately 5000 for positive and negative BMIM-PF6 ion beams. This indicated that BMIM-PF6 clusters with a size of a few tens of molecules were produced. With regard to the surface modification by BMIM-PF6 ion beams, positive and negative cluster ion beams were used to irradiate Si(1 0 0) and glass substrates. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations showed that the surface roughness of substrates increased. Furthermore, X-ray photoelectron spectroscopy (XPS) measurement showed that the composition ratio of layers deposited by positive or negative cluster ion beams was similar to that of BMIM-PF6 solvent.

Takaoka, Gikan H.; Takeuchi, Mitsuaki; Ryuto, Hiromichi; Ueda, Ryo

2013-07-01

364

Switchable ionic liquids as delignification solvents for lignocellulosic materials.  

PubMed

The transformation of lignocellulosic materials into potentially valuable resources is compromised by their complicated structure. Consequently, new economical and feasible conversion/fractionation techniques that render value-added products are intensely investigated. Herein an unorthodox and feasible fractionation method of birch chips (B.?pendula) using a switchable ionic liquid (SIL) derived from an alkanol amine (monoethanol amine, MEA) and an organic super base (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) with two different trigger acid gases (CO2 and SO2 ) is studied. After SIL treatment, the dissolved fractions were selectively separated by a step-wise method using an antisolvent to induce precipitation. The SIL was recycled after concentration and evaporation of anti-solvent. The composition of undissolved wood after MEA-SO2 -SIL treatment resulted in 80?wt?% cellulose, 10?wt?% hemicelluloses, and 3?wt?% lignin, whereas MEA-CO2 -SIL treatment resulted in 66?wt?% cellulose, 12?wt?% hemicelluloses and 11?wt?% lignin. Thus, the MEA-SO2 -SIL proved more efficient than the MEA-CO2 -SIL, and a better solvent for lignin removal. All fractions were analyzed by gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), (13) C nuclear magnetic resonance spectroscopy (NMR) and Gel permeation chromatography (GPC). PMID:24616172

Anugwom, Ikenna; Eta, Valerie; Virtanen, Pasi; Mäki-Arvela, Päivi; Hedenström, Mattias; Hummel, Michael; Sixta, Herbert; Mikkola, Jyri-Pekka

2014-04-01

365

Ultrafast vibrational dynamics and energy transfer in imidazolium ionic liquids.  

PubMed

Femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) is used as a probe for monitoring the vibrational dynamics of room temperature ionic liquids (ILs). The experiments are performed on a series of 1,3-dialkylimidazolium ILs containing the bis(trifluoromethylsulfonyl)imide [NTf2] anion. The effect of methylation of the cationic C2 position on the dephasing time is studied analyzing [NTf2]-ILs of 1-ethyl-3-methylimidazolium [EMIM], 1-ethyl-2,3-dimethylimidazolium [EMMIM], 1-butyl-3-methylimidazolium [BMIM], and 1-butyl-2,3-dimethylimidazolium [BMMIM]. Raman coherences are excited around ?1400 cm(-1), and the vibrational dephasing of the modes in the fingerprint region is monitored as a function of time. The results indicate that vibrational energy transfer occurs governed by the interionic interactions. This is suggested by mode beating involving vibrations beyond the excitation spectrum as well as systematic differences in the temporal dephasing behavior. In contrast, the length of the cationic alkyl side chain has a negligible impact on the vibrational dynamics. PMID:24697246

Namboodiri, Mahesh; Kazemi, Mehdi Mohammad; Zeb Khan, Tahir; Materny, Arnulf; Kiefer, Johannes

2014-04-23

366

Investigation of Anion Effects in Ionic Liquid-Nano Hybrid Materials.  

National Technical Information Service (NTIS)

The project investigated the following research areas: 1) Investigation of anion effects on the hydrohpilicity/hydrophobicity using self- assembled monolayers (SAMs) of thiol-functionalized ionic liquids on gold surfaces, 2) Construction of chips that res...

E. J. Roh J. K. Lee M. J. Park J. H. Park B. S. Lee

2006-01-01

367

Catalytic Conversion of Biomass to Fuels and Chemicals Using Ionic Liquids.  

National Technical Information Service (NTIS)

This project provides critical innovations and fundamental understandings that enable development of an economically-viable process for catalytic conversion of biomass (sugar) to 5-hydroxymethylfurfural (HMF). A low-cost ionic liquid (Cyphos 106) is disco...

A. Cooper H. Brown J. Holladay J. Li R. Zheng T. Rao W. Liu

2012-01-01

368

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

369

Plasticizing effect of ionic liquid on cellulose acetate obtained by melt processing.  

PubMed

Cellulose acetate (CA) plasticized by 1-butyl-3-methylimidazolium chloride (BMIMCl) and with diethylphtalate (DEP) was obtained by melt processing at 150°C. The effect and the interaction of ionic liquid with the cellulose acetate and their influence on structural, thermo-mechanical, rheological and tensile properties of CA materials were investigated. Ionic liquid (BMIMCl) has shown a good plasticization and more efficient destruction of the crystalline structure of cellulose acetate than the DEP plasticized CA. BMIMCl interacts intensively with CA molecules due to the pronounced van der Waals interactions, hydrogen bonding and electrostatic nature of ionic liquid. The tensile test and the low Young's modulus for plasticized CA suggest a strong reduction of the interaction between the CA chains due to the presence of the ionic liquid. PMID:24751249

Bendaoud, Amine; Chalamet, Yvan

2014-08-01

370

Synthesis of chemisorbed imidazolium and phosphonium cations by reaction of ionic liquid precursors with silica.  

PubMed

The reaction of four different basic ionic liquid precursors with Aerosil 300 is presented. Chemisorbed imidazolium and phosphonium cations, with silanolate anions as part of the silicatic support, were obtained and investigated with various solid state NMR techniques. PMID:20614073

Lungwitz, Ralf; Linder, Thomas; Sundermeyer, Jörg; Tkatchenko, Igor; Spange, Stefan

2010-08-28

371

Hydrotalcite catalysis in ionic liquid medium: a recyclable reaction system for heterogeneous Knoevenagel and nitroaldol condensation  

Microsoft Academic Search

Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF6 and [bmim]BF4 without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations.

Faiz Ahmed Khan; Jyotirmayee Dash; Rashmirekha Satapathy; Sarasij K. Upadhyay

2004-01-01

372

Recent advances in the applications of ionic liquids in protein stability and activity: a review.  

PubMed

Room temperatures ionic liquids are considered as miraculous solvents for biological system. Due to their inimitable properties and large variety of applications, they have been widely used in enzyme catalysis and protein stability and separation. The related information present in the current review is helpful to the researchers working in the field of biotechnology and biochemistry to design or choose an ionic liquid that can serve as a noble and selective solvent for any particular enzymatic reaction, protein preservation and other protein based applications. We have extensively analyzed the methods used for studying the protein-IL interaction which is useful in providing information about structural and conformational dynamics of protein. This can be helpful to develop and understanding about the effect of ionic liquids on stability and activity of proteins. In addition, the affect of physico-chemical properties of ionic liquids, viz. hydrogen bond capacity and hydrophobicity on protein stability are discussed. PMID:24599667

Patel, Rajan; Kumari, Meena; Khan, Abbul Bashar

2014-04-01

373

Direct methane conversion to methanol by ionic liquid-dissolved platinum catalysts.  

PubMed

Ternary systems of inorganic Pt salts and oxides, ionic liquids and concentrated sulfuric acid are effective at catalyzing the direct, selective oxidation of methane to methanol and appear to be more water tolerant than the Catalytica reaction. PMID:17082861

Cheng, Jihong; Li, Zaiwei; Haught, Mark; Tang, Yongchun

2006-11-28

374

Supramolecular ionic liquid gels for quasi-solid-state dye-sensitized solar cells.  

PubMed

A 1-propyl-3-methylimidazolium iodide based supramolecular ionic liquid gel was prepared through the host-guest interactions between a host of ?-cyclodextrin and a room temperature ionic liquid type guest, 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide, which contains bis(trifluoromethylsulfonyl)imide as the guest group. The gel-to-sol phase transition temperature of the prepared supramolecular ionic liquid gel could be tuned by the ratio of host to guest. The synthesized supramolecular ionic liquid gel was further applied in quasi-solid-state electrolyte dye-sensitized solar cells, which showed a power conversion efficiency of 4.79% under the simulated air mass 1.5 solar spectrum illumination at 100 mW cm(-2) and excellent long-term stability. PMID:24779535

Zhang, Wei; Yuan, Chao; Guo, Jiangna; Qiu, Lihua; Yan, Feng

2014-06-11

375

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

376

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

377

PALLADIUM-CATALYZED OXIDATION OF STYRENE AND ALKENES IN PRESENCE OF IONIC LIQUIDS (WACKER REACTION)  

EPA Science Inventory

The use of ionic liquids in various synthetic transformations is gaining significance due to the enhanced reaction rates, potential for recycling and compatibility with various organic compounds and organometallic catalysts. Palladium-catalyzed oxidation of styrene and other alk...

378

Composite Electrolytes for Lithium Batteries: Ionic Liquids in APTES Crosslinked Polymers  

NASA Technical Reports Server (NTRS)

Solvent free polymer electrolytes were made consisting of Li(+) and pyrrolidinium salts of trifluoromethanesulfonimide added to a series of hyperbranched poly(ethylene oxide)s (PEO). The polymers were connected by triazine linkages and crosslinked by a sol-gel process to provide mechanical strength. The connecting PEO groups were varied to help understand the effects of polymer structure on electrolyte conductivity in the presence of ionic liquids. Polymers were also made that contain poly(dimethylsiloxane) groups, which provide increased flexibility without interacting with lithium ions. When large amounts of ionic liquid are added, there is little dependence of conductivity on the polymer structure. However, when smaller amounts of ionic liquid are added, the inherent conductivity of the polymer becomes a factor. These electrolytes are more conductive than those made with high molecular weight PEO imbibed with ionic liquids at ambient temperatures, due to the amorphous nature of the polymer.

Tigelaar, Dean M.; Meador, Mary Ann B.; Bennett, William R.

2007-01-01

379

Nano-Sponge Ionic Liquid-Polymer Composite Electrolytes for Solid-State Lithium Power Sources.  

National Technical Information Service (NTIS)

Solid polymer gel electrolytes composed of 75 wt.% of the ionic liquid, 1-nbutyl- 2,3-dimethylimidazolium bis-trifluoromethanesulfonylimide with 1.0M lithium bis-trifluoromethanesulfonylimide and 25 wt.% poly(vinylidenedifluoro- hexafluoropropene) are cha...

E. Andreoli K. Liao K. A. McGrady P. Ajayan T. E. Sutto

2010-01-01

380

Application of thermodynamic-based retention time prediction to ionic liquid stationary phases.  

PubMed

First- and second-dimension retention times for a series of alkyl phosphates were predicted for multiple column combinations in GC×GC. This was accomplished through the use of a three-parameter thermodynamic model where the analytes' interactions with the stationary phases in both dimensions are known. Ionic liquid columns were employed to impart unique selectivity for alkyl phosphates, and it was determined that for alkyl phosphate compounds, ionic liquid columns are best used in the primary dimension. Retention coordinates for unknown phosphates are predicted from the thermodynamic parameters of a set standard alkyl phosphates. Additionally, we present changing retention properties of alkyl phosphates on some ionic liquid columns, due to suspected reaction between the analyte and column. This makes it difficult to accurately predict their retention properties, and in general poses a problem for ionic liquid columns with these types of analytes. PMID:24687987

Weber, Brandon M; Harynuk, James J

2014-06-01

381

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...

382

Metal Chlorides in Ionic Liquid Solvents Convert Sugars to 5-Hydroxymethylfurfural  

SciTech Connect

Sugars were converted to hydroxymethylfurfural (HMF) at high yield in ionic liquids without the addition of Bronsted acids. Very small amount of certain metal halides significantly reduced the fructose dehydration barrier in ionic liquids producing HMF at high yields. Most remarkably, glucose, a common sugar molecule, was selectively converted to HMF in good yield in ionic liquids containing a small amount of CrCl2. Thus CrCl2 is unique among metal chlorides tested for its effectiveness in both isomerizing glucose as well as dehydrating fructose. Only negligble amount of levulinic acid was formed in the reactions. The catalytic activity of metal chlorides for sugar conversion in ionic liquids is perhaps related to hydroxyl group of the sugar forming metal complexes with the unsaturated metal center.

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

2007-06-15

383

Structure of ionic liquids under external electric field: a molecular dynamics simulation  

Microsoft Academic Search

Understanding the structure of ionic liquids under external electric field (EEF) is very important for their applications in many fields, such as cells, electrowetting and electrospray. An all-atom molecular dynamic simulation was performed under EEF for [C2MIM][BF4] in order to explore the structure and properties of ionic liquids. It is found that EEF can change the distribution from disorder to

Yuling Zhao; Kun Dong; Xiaomin Liu; Suojiang Zhang; Jianjun Zhu; Jianji Wang

2011-01-01

384

Structure of ionic liquids under external electric field: a molecular dynamics simulation  

Microsoft Academic Search

Understanding the structure of ionic liquids under external electric field (EEF) is very important for their applications in many fields, such as cells, electrowetting and electrospray. An all-atom molecular dynamic simulation was performed under EEF for [C2MIM][BF4] in order to explore the structure and properties of ionic liquids. It is found that EEF can change the distribution from disorder to

Yuling Zhao; Kun Dong; Xiaomin Liu; Suojiang Zhang; Jianjun Zhu; Jianji Wang

2012-01-01

385

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

386

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

387

Toward a pKa Scale of N-base Amines in Ionic Liquids.  

PubMed

An electrochemical technique was used to investigate pKa values of some substituted secondary alicyclic (SA) amines, pyridines (py), anilines (AN), and triethylamine (Et3N) in different ionic liquids. The method involves cyclic voltammetry at a platinized Pt electrode. The experimental data were correlated with pKa values reported previously in aqueous solution, and Hammett parameters were correlated with pKa values in ionic liquids to determine ? values in these media. PMID:24689739

Millán, Daniela; Rojas, Mabel; Santos, José G; Morales, Javiera; Isaacs, Mauricio; Diaz, Carlos; Pavez, Paulina

2014-04-24

388

Palladium-Catalyzed Cascade Annulation To Construct Functionalized ?- and ?-Lactones in Ionic Liquids.  

PubMed

A highly efficient and mild palladium-catalyzed, one-pot, four-step cascade annulation has been developed to afford functionalized ?- and ?-lactones in moderate to good yields with high regio- and diastereoselectivities in ionic liquids. The employment of ionic liquids under mild reaction conditions makes this transformation green and practical. Especially, this reaction provided a novel and convenient methodology for the construction of naturally occurring biologically active ?- and ?-lactones. PMID:24866483

Li, Jianxiao; Yang, Wanfei; Yang, Shaorong; Huang, Liangbin; Wu, Wanqing; Sun, Yadong; Jiang, Huanfeng

2014-07-01

389

Understanding the High Solubility of CO2 in an Ionic Liquid with the Tetracyanoborate Anion  

Microsoft Academic Search

The ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate, [emim][B(CN)], shows greater CO solubility than several popular ionic liquids (ILs) of different anions including [emim]bis(trifluoromethylsulfonyl)imide [emim][TfN]. Herein, both classical molecular dynamics simulation and quantum mechanical calculations were used to understand the high solubility of CO in the [emim][B(CN)] IL. We found that the solubility is dictated by the cation-anion interaction, while the CO-anion interaction

Ravichandar Babarao; Sheng Dai; Deen Jiang

2011-01-01

390

Study on Preparation Process of Lubrication from 1-Decene with Acidic Ionic Liquid Catalyst  

Microsoft Academic Search

Poly-alpha-olefin (PAO) was researched over acidic ionic liquid catalyzed the oligomerization of 1-decene. Ionic liquid used was 1-butyl-3-methyl imidazolium as a cation and aluminum chloride as an anion, which could effectively catalyze oligomerization and had a higher selectivity. The optimum process conditions for the synthesis of PAO were that the reaction temperature was 160°C, the reaction time was 3 h,

H. Ding; B. Y. Zhang; J. Liu

2009-01-01

391

Arylation of Sensitive 1-(Pyrrolidin-1-yl)-diazen-1-ium-diolate in Ionic Liquids  

Microsoft Academic Search

The purpose of this research was to investigate the stability and reactivity of 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (PYRRO\\/NO) in dimethylformamide (DMF, as the reference solvent) and compare them to those obtained using different ionic liquids. The results of our experiments showed that PYRRO\\/NO is more stable (based on reactivity) in ionic liquid [EMIM][Ms] (with reaction yields up to 52%) than in DMF, that

Carlos A. Velázquez; Geoffrey M. Lynn; Vineet Kumar; Larry K. Keefer; Sanjay V. Malhotra

2010-01-01

392

Polymeric ionic liquids as selective coatings for the extraction of esters using solid-phase microextraction  

Microsoft Academic Search

A new class of stationary phase coatings for solid-phase microextraction (SPME) based on polymeric ionic liquids (PILs) is presented. PIL-based SPME coatings exhibit exceptional film stability, high thermal stability, reproducible extraction efficiencies, and long lifetimes. A series of three homologous polymeric imidazolium-based ionic liquid coatings were synthesized by free radical reaction. The fiber coatings were used to extract esters and

Fei Zhao; Yunjing Meng; Jared L. Anderson

2008-01-01

393

Theory Study of Different Substituent Length on Structure Property of N-methyl Morpholinium Ionic Liquid  

Microsoft Academic Search

By using at density functional theory (DFT) at B3LYP\\/6-31G* levels, The morpholinium ionic liquid with different substituent length have been studied. The computed results indicate that the ionic liquid formed by N-methyl ethyl morpholinium and a bromine ion has three structure (mon, nop, orth) and six position. Three hydrogen bond have been formed in each position, The hydrogen bond between

Wang Li-min; Chu De-qing

2010-01-01

394

Study on Structure Property of Different Cation and Anion Morpholinium Ionic Liquid  

Microsoft Academic Search

By using density functional theory (DFT) at B3LYP\\/6-31G* levels, The effect of optimized geometries and binding energies of morpholinium ionic liquid have been studied by different anions or cations. The computed results indicate that the ionic liquid formed by different anions and cations has three structures (mon, nop, orth) and six positions. Three hydrogen bond have been formed in each

Xia Chuan; Wang Limin

2010-01-01

395

Compatibility of quaternary ammonium-based ionic liquid electrolytes with electrodes in lithium ion batteries  

Microsoft Academic Search

Electrochemical intercalation\\/deintercalation behavior of lithium into\\/from electrodes of lithium ion batteries was comparatively investigated in 1mol\\/L LiClO4 ethylene carbonate–diethyl carbonate (EC-DEC) electrolyte and a quaternary ammonium-based ionic liquid electrolyte. The natural graphite anode exhibited satisfactory electrochemical performance in the ionic liquid electrolyte containing 20vol.% chloroethylenene carbonate (Cl-EC). This is attributed to the mild reduction of solvated Cl-EC molecules at the

Honghe Zheng; Bao Li; Yanbao Fu; Takeshi Abe; Zempachi Ogumi

2006-01-01

396

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

397

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

398

Aggregation behavior of long-chain imidazolium ionic liquids in ethylammonium nitrate  

Microsoft Academic Search

The aggregation behavior of long-chain imidazolium ionic liquids, 1-alkyl-3-methyl-imidazolium bromide (CnmimBr, n?=?12, 14, 16) was studied by surface tension measurements in a room temperature ionic liquid, ethylammonium nitrate (EAN),\\u000a at various temperatures. A series of parameters including critical micelle concentration (cmc), surface tension at the cmc\\u000a (?\\u000a cmc), and the effectiveness of surface tension reduction (?cmc) were obtained. In addition,

Wenpei Kang; Bin Dong; Yanan Gao; Liqiang Zheng

2010-01-01

399

Conjugate addition of indoles to ?,?-unsaturated ketones using Cu(OTf) 2 immobilized in ionic liquids  

Microsoft Academic Search

Indoles undergo smooth conjugate addition with ?,?-unsaturated ketones in the presence of 10mol% copper(II) triflate immobilized in air and moisture stable [bmim]BF4 ionic liquid under mild conditions to afford the corresponding conjugate addition products in high to quantitative yields. The recovery of Cu(OTf)2 is facilitated by the ionic liquid. The recovered catalyst was reused four to five times with consistent

J. S. Yadav; B. V. S. Reddy; Gakul Baishya; K. V. Reddy; A. V. Narsaiah

2005-01-01

400

Ionic-liquid materials for the electrochemical challenges of the future  

Microsoft Academic Search

Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal\\/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells),

Michel Armand; Frank Endres; Douglas R. Macfarlane; Hiroyuki Ohno; Bruno Scrosati

2009-01-01

401

A classical density functional theory for interfacial layering of ionic liquids  

Microsoft Academic Search

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

Jianzhong Wu; Tao Jiang; Deen Jiang; Zhehui Jin; Douglous Henderson

2011-01-01

402

Characterisation and application of carbon film electrodes in room temperature ionic liquid media  

Microsoft Academic Search

Carbon film electrodes have been characterised in the room temperature ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (BmimNTF2), 1-butyl-1-methylpyrrolidinium bis(trifluoromethane)sulfonimide, (BpyrNTF2) and 1-butyl-3-methylimidazolium nitrate (BmimNO3), by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behaviour of the ionic liquids depended on both cation and anion of these electrolytes. Oxygen reduction is clearly visible at carbon film electrodes – after oxygen removal the potential

Rasa Pauliukaite; Andrew P. Doherty; Kevin D. Murnaghan; Christopher M. A. Brett

2008-01-01

403

Ionic liquid electrolytes compatible with graphitized carbon negative without additive and their effects on interfacial properties  

Microsoft Academic Search

Introduction of bis(fluorosulfonyl)imide (FSI) as an anion to an ambient-temperature ionic liquid electrolyte based on 1-ethyl-3-methylimidazolium (EMI) as well as lithium (Li) cations can provide a reversible Li intercalation into a graphitized electrode, while such intercalation is completely irreversible without FSI. The surface-layer components on the graphitized electrodes, cycled in the ionic liquid electrolytes with and without FSI, were found

Toshinori Sugimoto; Manabu Kikuta; Eriko Ishiko; Michiyuki Kono; Masashi Ishikawa

2008-01-01

404

Increased stability of an esterase from Bacillus stearothermophilus in ionic liquids as compared to organic solvents  

Microsoft Academic Search

Three different ionic liquids, 1-butyl-3-methyl imidazolium bis[(trifluoromethyl)sulfonyl]amide [BMIM][BTA], 1-butyl-3-methyl imidazolium hexafluorophosphate [BMIM][PF6] and 1-butyl-3-methyl imidazolium tetrafluoroborate [BMIM][BF4] were used as reaction media for the transesterification of 1-phenylethanol catalysed by esterases from Bacillus subtilis and Bacillus stearothermophilus. No transesterification activity could be detected in the ionic liquids when the lyophilised powder of the esterases was used as biocatalysts. By immobilising the

Mattias Persson; Uwe T. Bornscheuer

2003-01-01

405

Lithium-air batteries using hydrophobic room temperature ionic liquid electrolyte  

Microsoft Academic Search

Lithium-air batteries using hydrophobic ionic liquid consisting of 1-alkyl-3-methyl imidazolium cation and perfluoroalkylsulfonyl imide anion were investigated. 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, which has high conductivity and prevents hydrolysis of the lithium anode, showed the best electrolyte performance. The cell worked for 56 days in air, and the cathode carbon materials showed high discharge capacity of 5360mAhg?1. In addition to hydrophobic ionic liquids

Takashi Kuboki; Tetsuo Okuyama; Takahisa Ohsaki; Norio Takami

2005-01-01

406

Sulfamides and glymes as aprotic solvents for lithium batteries  

SciTech Connect

In view of the high reactivity of the lithium metal, lithium batteries must operate in an aprotic environment, which can either be a conducting polymer, a liquid solvent, or a mixture of them. Two families of aprotic liquids were considered as solvents for lithium bis(trifluoromethylsulfone)imide (LiCF{sub 3}SO{sub 2}NSO{sub 2}CF{sub 3} or LiTFSI). The first one is the substituted sulfamides, R{sub 1}R{sub 2}NSO{sub 2}NR{sub 3}R{sub 4}, where the R groups are either methyl, ethyl, or methoxyethyl (CH{sub 2}CH{sub 2}OCH{sub 3}), and the second one is the glymes, CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3}, for n up to 10. The phase diagrams, potential windows, conductivities, and the lithium interfacial resistances of the solutions were investigated, often as a function of temperature. The potential use of these solvents for different types of batteries is discussed.

Choquette, Y. [IREQ, Varennes, Quebec (Canada); Brisard, G.; Parent, M. [Univ. de Sherbrooke, Quebec (Canada). Dept. of Chemistry; Brouillette, D.; Perron, G.; Desnoyers, J.E. [INRS-Energie et Materiaux, Varennes, Quebec (Canada); Armand, M.; Gravel, D.; Slougui, N. [Univ. de Montreal, Quebec (Canada). Dept. of Chemistry

1998-10-01

407

Extraction of S- and N-compounds from the mixture of hydrocarbons by ionic liquids as selective solvents.  

PubMed

Liquid-liquid extraction is an alternative method that can be used for desulfurization and denitrification of gasoline and diesel fuels. Recent approaches employ different ionic liquids as selective solvents, due to their general immiscibility with gasoline and diesel, negligible vapor pressure, and high selectivity to sulfur- and nitrogen-containing compounds. For that reason, five imidazolium-based ionic liquids and one pyridinium-based ionic liquid were selected for extraction of thiophene, dibenzothiophene, and pyridine from two model solutions. The influences of hydrodynamic conditions, mass ratio, and number of stages were investigated. Increasing the mass ratio of ionic liquid/model fuel and multistage extraction promotes the desulfurization and denitrification abilities of the examined ionic liquids. All selected ionic liquids can be reused and regenerated by means of vacuum evaporation. PMID:23843736

Gabri?, Beata; Sander, Aleksandra; Cvjetko Bubalo, Marina; Macut, Dejan

2013-01-01

408

Effect of Ammonium- and Phosphonium-Based Ionic Liquids on the Separation of Lactic Acid by Supported Ionic Liquid Membranes (SILMs)  

PubMed Central

Biodegradable polymers have attracted much attention from an environmental point of view. Optically pure lactic acid that can be prepared by fermentation is one of the important raw materials for biodegradable polymer. The separation and purification of lactic acid from the fermentation broth are the major portions of the production costs. We proposed the application of supported ionic liquid membranes to recovering lactic acid. In this paper, the effect of ionic liquids, such as Aliquat 336, CYPHOS IL-101, CYPHOS IL-102, CYPHOS IL-104, CYPHOS IL-109 and CYPHOS IL-111 on the lactic acid permeation have been studied. Aliquat 336, CYPHOS IL-101 and CYPHOS IL-102 were found to be the best membrane solvents as far as membrane stability and permeation of lactic acid are concerned. CYPHOS IL-109 and CYPHOS IL-111 were found to be unsuitable, as they leak out from the pores of the supported liquid membrane (SLM), thereby allowing free transport of lactic acid as well as hydrochloric acid. CYPHOS IL-102 was found to be the most adequate (Permeation rate = 60.41%) among these ionic liquids as far as the separation of lactic acid is concerned. The permeation mechanisms, by which ionic liquid-water complexes act as the carrier of lactate and hydrochloric acid, were proposed. The experimental permeation results have been obtained as opposed to the expected values from the solution-diffusion mechanism.

Matsumoto, Michiaki; Panigrahi, Abhishek; Murakami, Yuuki; Kondo, Kazuo

2011-01-01

409

Cooperative effect of ionic liquid solvents in microfluidic devices for fabricating monodisperse metal nanoparticles  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids have been receiving attention as alternatives to traditional organic solvents. In particular, 1,3-dialkylimidazolium ionic liquids are attractive because their properties are easily tailored by altering the counteranion and type of alkyl chains on the imidazolium ring. Ionic liquids are finding use as dual-function solvents and stabilizing agents for nanoparticles. They are able to solvate a wide variety of species and are thought to consist of polar and non-polar domains of hydrogen bonded networks, which may be able to stabilize and even template nanoparticle growth. They have several other properties (e.g., nonflammability, nonvolatility, recyclability) that potentially make them more environmentally sound compared to some traditional organic solvents. We have developed different microfluidic architectures for the synthesis of gold and silver nanoparticles in ionic liquid flows. The large surface area-to-volume ratio within microscale channels allows for improved heat and mass transport and more homogeneous reaction conditions, leading to monodisperse nanoparticle products. Additionally, microfluidic syntheses allow for finer control over reaction parameters compared to traditional batch reactions. Herein, we examined the combined beneficial effects of ionic liquid flows and different microfluidic systems to prepare gold and silver nanoparticles that are more monodisperse than those produced in analogous batch reactions. The compatibility of ionic liquids with inexpensive polydimethylsiloxane microfluidic devices makes it a unique system for the reproducible synthesis of high-quality nanoparticles.

Lazarus, Laura L.

410

Study of tribochemical decomposition of ionic liquids on a nascent steel surface  

NASA Astrophysics Data System (ADS)

Tribological properties and the decomposition process of ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide) on a nascent surface of bearing steel 52100 were investigated by a ball-on-disk friction tester in a vacuum chamber equipped with a quadrupole mass spectrometer (Q-MS). Ionic liquids exhibited better tribological properties than synthetic hydrocarbon oil (multialkylated cyclopentane (MAC)) in high vacuum conditions. The induction period for decomposition of MAC was about 10 km, while no obvious gaseous products were observed for ionic liquids even after a sliding distance of 22 km under the same mechanical conditions. The mass spectra indicated that both the anionic and cationic moieties of ionic liquids decomposed on the nascent steel surface during friction processes. The cationic moiety with a longer alkyl chain was more difficult to decompose on the nascent steel surface than that with a shorter alkyl chain. XPS analysis revealed that the tribofilm formed by ionic liquid was mainly composed of FeF 2 and FeS, which deactivated the nascent surface. As a result, desorption rate of gaseous products decreased appreciably comparing with MAC. The critical load for the mechanical activation of the decomposition correspondingly increased from 1.1 N of MAC to 8 N of ionic liquids.

Lu, Renguo; Mori, Shigeyuki; Kobayashi, Kimihiro; Nanao, Hidetaka

2009-08-01

411

Room temperature imidazolium ionic liquid: a solvent for extraction of carbamates prior to liquid chromatographic analysis.  

PubMed

A simple and rapid method for preconcentration of carbamate insecticides, including methomyl, propoxur, carbofuran, carbaryl, isoprocarb, methiocarb and promecarb, has been developed. It was based on a liquid-liquid microextraction using a [C(4)MIM][PF(6)] room temperature ionic liquid as an extraction solvent prior to analysis by high performance liquid chromatography with UV detection. Experimental parameters affecting the extraction performance, such as the volumes of sample, extractant and dissolving solvent, and extraction time, were studied. Under the selected conditions, the enrichment factors in the range between 10 and 25 could be achieved with the limit of detection in the range of 2-40 ?g L(-1), and with the relative standard deviations of lower than 0.6 and 10.2% for retention time and peak area, respectively. The proposed method offers advantages in reduction of the exposure danger to toxic solvents used in the conventional liquid-liquid extraction, simplicity of the extraction processes, rapidity, and sensitivity enhancement. The method was demonstrated to apply to the analysis of fruit and natural surface water samples. PMID:21641434

Vichapong, Jitlada; Burakham, Rodjana; Srijaranai, Supalax; Grudpan, Kate

2011-06-15

412

Influence of Ionic Liquids in Quasi-Solid State Electrolyte on Dye-Sensitized Solar Cell Performance  

Microsoft Academic Search

Room temperature ionic liquids have been used as electrolytes to investigate the performance and the characteristics in dye-sensitized solar cells (DSSCs). We focused on quasi-solid state electrolyte using ionic liquids, which are non-volatile liquids having relatively high conductivities. We studied the performance of the DSSC device with different anion or cation structures of ionic liquids. The power conversion efficiency of

Hyun-Jeong Lee; Jin-Kook Lee; Mi-Ra Kim; Won Suk Shin; Sung-Ho Jin; Kyong-Hoon Kim; Dae-Won Park; Sang-Wook Park

2006-01-01

413

Comparison of uranyl extraction mechanisms in an ionic liquid by use of malonamide or malonamide-functionalized ionic liquid.  

PubMed

The extraction of uranyl from acidic (HNO(3)) aqueous solutions toward an ionic liquid phase, C(1)-C(4)-imTf(2)N (1-methyl,3-butylimidazolium Tf(2)N), has been investigated as a function of initial acid concentration and ligand concentration for two different extracting moieties: a classical malonamide, N,N'-dimethyl-N,N'-dibutylmalonamide (DMDBMA) and a functionalized IL composed of the Tf(2)N(-) anion and an imidazolium cation on which a malonamide pattern has been grafted (FIL-MA). The extraction mechanism, as demonstrated through the influence of added C(1)-C(4)-imCl or added LiTf(2)N in the aqueous phase, is slightly different between the DMDBMA and FIL-MA extracting agents. Modeling of the extraction data evidences a double extraction mechanism, with cation exchange of UO(2)(2+)versus 2 H(+) for DMDBMA or versus C(1)-C(4) -im(+) and H(+) for FIL-MA at low acidic values, and through anion exchange of [UO(2)(NO(3))(3)](-)versus Tf(2)N(-) for both ligands at high HNO(3) concentrations. The FIL-MA molecule is more efficient than its classical DMDBMA parent. PMID:22584668

Bonnaffé-Moity, Marieke; Ouadi, Ali; Mazan, Valérie; Miroshnichenko, Stanislav; Ternova, Dariia; Georg, Sylvia; Sypula, Michal; Gaillard, Clotilde; Billard, Isabelle

2012-07-01

414

Biopolymer-supported ionic-liquid-phase ruthenium catalysts for olefin metathesis.  

PubMed

Original ruthenium supported ionic liquid phase (SILP) catalysts based on alginates as supports were developed for olefin metathesis reactions. The marine biopolymer, which fulfills most of the requisite properties for a support such as widespread abundance, insolubility in the majority of organic solvents, a high affinity for ionic liquids, high chemical stability, biodegradability, low cost, and easy processing, was impregnated by [bmim][PF6 ] containing an ionically tagged ruthenium catalyst. These biosourced catalysts show promising performances in ring-closing metathesis (RCM) and cross-metathesis (CM) reactions, with a high level of recyclability and reusability combined with a good reactivity. PMID:24616203

Clousier, Nathalie; Filippi, Alexandra; Borré, Etienne; Guibal, Eric; Crévisy, Christophe; Caijo, Fréderic; Mauduit, Marc; Dez, Isabelle; Gaumont, Annie-Claude

2014-04-01

415

Application of ionic liquid-based dispersive liquid-liquid microextraction for the analysis of ochratoxin A in rice wines.  

PubMed

A novel and rapid ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) method combined with liquid chromatography and a fluorescence detector for the analysis of ochratoxin A in rice wines is presented. The following parameters were systematically investigated: type and volume of ionic liquid, volume of dispersive solvent, salt addition, sample pH, and vortex time. Rice wine samples were first diluted to 18% alcohol with deionized water, and the pH was adjusted to 3.0. A DLLME procedure was followed that included IL ([HMIM][PF6]) and ethanol as the extraction and dispersive solvents, respectively. Under the optimized experimental conditions, good linearity was obtained with a correlation coefficient (r) of 0.9998 and a limit of detection (LOD) of 0.04?gL(-1). The recoveries ranged from 75.9% to 82.1% with an RSD below 10.4%. The proposed method was successfully applied to analyse OTA samples from several rice wine brands collected in Guangdong province, China. PMID:24837956

Lai, Xianwen; Ruan, Chunqiang; Liu, Ruicen; Liu, Chenglan

2014-10-15

416

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

417

New Class of Solvents for TRU Dissolution and Separation: Ionic Liquids. Report for September 15, 2001-September 14, 2004.  

National Technical Information Service (NTIS)

Through the current EMSP funding, solvent extraction technologies based on liquid-liquid partitioning of TRU to an Ionic Liquid phase containing conventional complexants has been shown to be viable. The growing understanding of the role that the different...

R. D. Rogers

2005-01-01

418

Preparation and characterisation of high-density ionic liquids incorporating halobismuthate anions.  

PubMed

A range of ionic liquids containing dialkylimidazolium cations and halobismuthate anions ([BiBrxClyIz](-) and [Bi2BrxClyIz](-)) were synthesised by combining dialkylimidazolium halide ionic liquids with bismuth(iii) halide salts. The majority were room temperature liquids, all with very high densities. The neat ionic liquids and their mixtures with 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide were characterised using Densitometry, Viscometry, NMR Spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI), Liquid Secondary Ion Mass Spectrometry (LSIMS), Matrix-assisted Laser Desorption/Ionization Mass Spectrometry (MALDI), X-Ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA), to establish their speciation and suitability for high-temperature applications. PMID:24898158

Cousens, Nico E A; Taylor Kearney, Leah J; Clough, Matthew T; Lovelock, Kevin R J; Palgrave, Robert G; Perkin, Susan

2014-06-24

419

Modulating enzyme activity using ionic liquids or surfactants.  

PubMed

One of the important strategies for modulating enzyme activity is the use of additives to affect their microenvironment and subsequently make them suitable for use in different industrial processes. Ionic liquids (ILs) have been investigated extensively in recent years as such additives. They are a class of solvents with peculiar properties and a "green" reputation in comparison to classical organic solvents. ILs as co-solvents in aqueous systems have an effect on substrate solubility, enzyme structure and on enzyme-water interactions. These effects can lead to higher reaction yields, improved selectivity, and changes in substrate specificity, and thus there is great potential for IL incorporation in biocatalysis. The use of surfactants, which are usually denaturating agents, as additives in enzymatic reactions is less reviewed in recent years. However, interesting modulations in enzyme activity in their presence have been reported. In the case of surfactants there is a more pronounced effect on the enzyme structure, as can be observed in a number of crystal structures obtained in their presence. For each additive and enzymatic process, a specific optimization process is needed and there is no one-fits-all solution. Combining ILs and surfactants in either mixed micelles or water-in-IL microemulsions for use in enzymatic reaction systems is a promising direction which may further expand the range of enzyme applications in industrial processes. While many reviews exist on the use of ILs in biocatalysis, the present review centers on systems in which ILs or surfactants were able to modulate and improve the natural activity of enzymes in aqueous systems. PMID:24281758

Goldfeder, Mor; Fishman, Ayelet

2014-01-01

420

Going full circle: phase-transition thermodynamics of ionic liquids.  

PubMed

We present the full enthalpic phase transition cycle for ionic liquids (ILs) as examples of non-classical salts. The cycle was closed for the lattice, solvation, dissociation, and vaporization enthalpies of 30 different ILs, relying on as much experimental data as was available. High-quality dissociation enthalpies were calculated at the G3 MP2 level. From the cycle, we could establish, for the first time, the lattice and solvation enthalpies of ILs with imidazolium ions. For vaporization, lattice, and dissociation enthalpies, we also developed new prediction methods in the course of our investigations. Here, as only single-ion values need to be calculated and the tedious optimization of an ion pair can be circumvented, the computational time is short. For the vaporization enthalpy, a very simple approach was found, using a surface term and the calculated enthalpic correction to the total gas-phase energy. For the lattice enthalpy, the most important constituent proved to be the calculated conductor-like screening model (COSMO) solvation enthalpy in the ideal electric conductor. A similar model was developed for the dissociation enthalpy. According to our assessment, the typical error of the lattice enthalpy would be 9.4 kJ mol(-1), which is less than half the deviation we get when using the (optimized) Kapustinskii equation or the recent volume-based thermodynamics (VBT) theory. In contrast, the non-optimized VBT formula gives lattice enthalpies 20 to 140?kJ?mol(-1) lower than the ones we assessed in the cycle, because of the insufficient description of dispersive interactions. Our findings show that quantum-chemical calculations can greatly improve the VBT approaches, which were parameterized for simple, inorganic salts with ideally point-shaped charges. In conclusion, we suggest the term "augmented VBT", or "aVBT", to describe this kind of theoretical approach. PMID:21538602

Preiss, Ulrich; Verevkin, Sergey P; Koslowski, Thorsten; Krossing, Ingo

2011-05-27

421

Ionic Liquids as Novel Lubricants and /or Lubricant Additives  

SciTech Connect

This ORNL-GM CRADA developed ionic liquids (ILs) as novel lubricants or oil additives for engine lubrication. A new group of oil-miscible ILs have been designed and synthesized with high thermal stability, non-corrosiveness, excellent wettability, and most importantly effective anti-scuffing/anti-wear and friction reduction characteristics. Mechanistic analysis attributes the superior lubricating performance of IL additives to their physical and chemical interactions with metallic surfaces. Working with a leading lubricant formulation company, the team has successfully developed a prototype low-viscosity engine oil using a phosphonium-phosphate IL as an anti-wear additive. Tribological bench tests of the IL-additized formulated oil showed 20-33% lower friction in mixed and elastohydrodynamic lubrication and 38-92% lower wear in boundary lubrication when compared with commercial Mobil 1 and Mobil Clean 5W-30 engine oils. High-temperature, high load (HTHL) full-size engine tests confirmed the excellent anti-wear performance for the IL-additized engine oil. Sequence VID engine dynamometer tests demonstrated an improved fuel economy by >2% for this IL-additized engine oil benchmarked against the Mobil 1 5W-30 oil. In addition, accelerated catalyst aging tests suggest that the IL additive may potentially have less adverse impact on three-way catalysts compared to the conventional ZDDP. Follow-on research is needed for further development and optimization of IL chemistry and oil formulation to fully meet ILSAC GF-5 specifications and further enhance the automotive engine efficiency and durability.

Qu, J. [ORNL] [ORNL; Viola, M. B. [General Motors Company] [General Motors Company

2013-10-31

422

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

2013-11-01

423

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

424

Thermoreversible nanogel shuttle between ionic liquid and aqueous phases.  

PubMed

We describe a nanogel that can reversibly shuttle between a hydrophobic ionic liquid (IL) phase and an aqueous phase in response to temperature changes. A thermosensitive diblock copolymer, consisting of poly(ethylene oxide) (PEO) as the first segment and a random copolymer of N-isopropylacrylamide (NIPAm) and N-acryloyloxysuccinimide (NAS) as the second segment, was prepared as a nanogel precursor using anionic ring-opening polymerization of EO followed by reversible addition-fragmentation chain-transfer (RAFT) polymerization of NIPAm and NAS. After the micellization of the diblock copolymer in an aqueous solution upon heating to temperatures higher than the lower critical solution temperature (LCST) of the second segment, a coupling reaction of the NAS group of the P(NIPAm-r-NAS) core with ethylenediamine gave a nanogel with a well-solvated PEO corona. The nanogel exhibited contrasting thermosensitivities in the aqueous and IL phases. Dynamic light scattering measurements revealed that the nanogel exhibited LCST phase behavior (low-temperature-swollen/high-temperature-shrunken) in the aqueous phase and the opposite upper critical solution temperature (UCST) phase behavior (high-temperature-swollen/low-temperature-shrunken) in hydrophobic ILs. The nanogel favored the aqueous phase at low temperatures and the IL phase at high temperatures because of the solubility changes in the PEO corona. Upon increasing the temperature, the nanogel underwent a swollen-to-shrunken phase change in the aqueous phase, a transfer from the aqueous phase to the IL phase, and a shrunken-to-swollen phase change in the IL phase. These processes were thermally reversible, which made the round-trip shuttling of the nanogel between the aqueous and IL phases possible. PMID:24168637

Ueki, Takeshi; Sawamura, Shota; Nakamura, Yutaro; Kitazawa, Yuzo; Kokubo, Hisashi; Watanabe, Masayoshi

2013-11-12

425

Static and transport properties of alkyltrimethylammonium cation-based room-temperature ionic liquids.  

PubMed

We have measured physicochemical properties of five alkyltrimethylammonium cation-based room-temperature ionic liquids and compared them with those obtained from computational methods. We have found that static properties (density and refractive index) and transport properties (ionic conductivity, self-diffusion coefficient, and viscosity) of these ionic liquids show close relations with the length of the alkyl chain. In particular, static properties obtained by experimental methods exhibit a trend complementary to that by computational methods (refractive index ? [polarizability/molar volume]). Moreover, the self-diffusion coefficient obtained by molecular dynamics (MD) simulation was consistent with the data obtained by the pulsed-gradient spin-echo nuclear magnetic resonance technique, which suggests that computational methods can be supplemental tools to predict physicochemical properties of room-temperature ionic liquids. PMID:24702446

Seki, Shiro; Tsuzuki, Seiji; Hayamizu, Kikuko; Serizawa, Nobuyuki; Ono, Shimpei; Takei, Katsuhito; Doi, Hiroyuk