Haut PDF ELLE & IL : enantioselective liquid-liquid extraction and ionic liquids

ELLE & IL : enantioselective liquid-liquid extraction and ionic liquids

ELLE & IL : enantioselective liquid-liquid extraction and ionic liquids

118 ELLE & IL: Enantioselective liquid-liquid extraction and ionic liquids Viacheslav Zgonnik, PhD thesis, Université Toulouse III - Paul Sabatier, 19 July 2011 La métathèse croisée est peut-être la découverte la plus intéressante de ce travail. Simple et puissant ce procédé ouvre la voie à la synthèse simple des nouveaux liquides ioniques. Chaque liquide ionique de départ doit possèder une partie hydrophile et une partie hydrophobe. Ensemble dans le système biphasique, les ions se répartissent selon leur nature. L'avantage de cette méthode est que nous mettons en réaction deux liquides ioniques pour obtenir deux nouveaux liquides ioniques avec un rendement quantitatif et avec 100% d'économie d’atomes. Nous avons été inspirés par cette réaction de métathèse croisée pour développer le processus d’ELLE dans les LIs. Tous les composés racémiques ont été modifiés en ajoutant un anion hydrophobe dans leurs structures pour les rendre utilisables dans ce genre de processus. Les LIC tartrates de tétrabutylphosphonium ont été choisis en raison de leur simple mode de préparation. Le composé racémique que nous avons sélectionné pour les tests approfondis était le pipécoloxylidide, parce qu’il a été le substrat modèle du projet INTENANT. Finalement, la paire LIC tartrate/ pipécoloxylidide a donné les meilleurs résultats de ce travail (Figure 5-3).
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Small spatial scales in wetting on non-structured and structured surfaces: thin films of liquid crystals & small-scales wetting properties of ionic liquids

Small spatial scales in wetting on non-structured and structured surfaces: thin films of liquid crystals & small-scales wetting properties of ionic liquids

J m -2 accounts for the data close to T NI , and such a value is quite plausible. However, even if this specific result is satisfactory, further work is required to understand why on water the LB boundary jumps so suddenly, and which is the structure of the thick molecular film. The behavior of thin hybrid nematic films has been the subject of extensive analyses, both from the theoretical and the experimental point of view. 39-41 It is widely accepted that when the planar anchoring is degenerate, which is the case here, the value of the order parameter is not homogeneous within the film. Then the whole Landau-de Gennes free energy is required for a proper description: both local orientation and local value of the order parameter are needed. 27 While a continuous description works acceptably for the striped films, where the local orientation plays the major role, this is probably not the case for the thick molecular films.
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Liquid-liquid miscibility and volumetric properties of aqueous solutions of ionic liquids as a function of temperature

Liquid-liquid miscibility and volumetric properties of aqueous solutions of ionic liquids as a function of temperature

methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C 1 C 4 Pyr- ro][NTf 2 ]), butyltrimethylammonium bis(trifluoromethylsulfo- nyl)imide ([N 4111 ][NTf 2 ]). Prior to the study the volumetric properties, the phase behav- iour of the binary systems containing hydrophobic ILs was investi- gated in order to determine their mutual solubility with water. A nephelometric method [41,42] was used to detect cloud points. The volumetric properties are then investigated for IL mole frac- tions where only one liquid phase is observed. Excess molar vol- umes, defined as the difference between the actual molar volume of the mixture and that of an ideal solution at the same tempera- ture, pressure, and composition, represent the deviation from the ideal behaviour of the mixtures. These values were calculated for all the {IL + water} mixtures from density measurements per- formed at atmospheric pressure as a function of temperature be- tween (293 and 343) K at 5 K intervals and of the composition of the liquid mixture. In each case at least eight compositions for each binary system were examined.
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The role of association of ions in ionic liquid/molecular solvent mixtures on metal extraction

The role of association of ions in ionic liquid/molecular solvent mixtures on metal extraction

previously been extensively studied in some recent articles. 17–19 Various mixtures of compositions ranging from pure IL to pure BA were considered. The extraction efficiency was evaluated for each extracting mixture. In parallel, the molecular structure and organization of the extracting phase were assessed through the measurement of the association of the IL and spectroscopic investigations. Other mixtures composed of BA and a hydrophobic IL have also been studied for comparison. Two ILs containing the same octyl chain but with various cations (1-methyl-3-octyl- pyrrolidinium bis(trifluoromethylsulfonyl)imide, [C 1 C 8 Pyrro]- [NTf 2 ], 1-octyl-pyridinium bis(trifluoromethylsulfonyl)imide, [C 8 Pyr][NTf 2 ]) and one with a shorter alkyl chain (1-butyl-3- methyl-imidazolium bis(trifluoromethylsulfonyl)imide, [C 1 C 4 Im]- [NTf 2 ]) were considered. All these ILs were chosen because they are fully miscible with BA, are immiscible with water and present a reduced viscosity. The addition of BA to the IL is expected to modify the interactions in the system, as evidenced via the ionicity and spectroscopy results, and thus influence the mechanism of extraction of Pt( IV ), which is under the stable [PtCl 6 ] 2 form under our chemical conditions. 20
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High temperature carbon–carbon supercapacitor using ionic liquid as electrolyte

High temperature carbon–carbon supercapacitor using ionic liquid as electrolyte

Scheme 1. N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR 14 TFSI). Ionic liquids (ILs) are room temperature molten salts, they are entirely composed of cations and anions, the nature of which influences the chemical/electrochemical and physical proper- ties. Particularly, the cation limits the negative potential window while the anion affects the positive potential window as well as the melting point, which in turn affects the working tem- perature range for high conductivity. ILs typically show a very low vapour pressure, high thermal stability, wide electrochem- ical windows and good conductivity at temperatures (≥60 ◦ C)
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Cationic Dye Removal from Aqueous Solutions Using Ionic Liquid and Nonionic Surfactant-Ionic Liquid Systems: A Comparative Study Based upon Experimental Design

Cationic Dye Removal from Aqueous Solutions Using Ionic Liquid and Nonionic Surfactant-Ionic Liquid Systems: A Comparative Study Based upon Experimental Design

used in separation processes (Poole and Poole, 2010). On the other hand, their miscibility with water can be complete (hydrophilic IL) or partial (hydrophobic IL). This behavior is mainly due to the nature of the anion (Shvedene et al., 2005), which forms hydrogen bonds, for instance, in the case of 1-butyl-3-methylimi- dazolium chloride [C4mim]Cl. The biphasic system is, therefore, formed by combin- ing water=[C4mim]Cl and inorganic salt above a certain critical concentration (Safavi et al., 2008). He et al. (2005) used [C4mim]Cl to separate testosterone and epitestosterone from an aqueous solution. Other works based on ionic liquids and water-structuring salts have been reported (e.g., protein extraction with a series of ionic liquids, by Pei et al. (2009)). Vijayaraghavan et al. (2006) used N-butyl, N-methyl pyrrolidinium bis (trifluoromethanesulfonyl) amide to extract azo dye from water. The initial extraction efficiency was about 50%, while, with two or three extraction stages, it easily reached 95%. Li et al. (2007) investigated acid dye extrac- tions from aqueous solutions using 1-butyl-3-methylimidazolium hexafluoropho- sphate ([C4mim]PF6); the ion exchange process was predominant for extraction of dyes and obviously responsible for the high distribution constant.
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Cationic Dye Removal from Aqueous Solutions Using Ionic Liquid and Nonionic Surfactant-Ionic Liquid Systems: A Comparative Study Based upon Experimental Design

Cationic Dye Removal from Aqueous Solutions Using Ionic Liquid and Nonionic Surfactant-Ionic Liquid Systems: A Comparative Study Based upon Experimental Design

used in separation processes (Poole and Poole, 2010). On the other hand, their miscibility with water can be complete (hydrophilic IL) or partial (hydrophobic IL). This behavior is mainly due to the nature of the anion (Shvedene et al., 2005), which forms hydrogen bonds, for instance, in the case of 1-butyl-3-methylimi- dazolium chloride [C4mim]Cl. The biphasic system is, therefore, formed by combin- ing water=[C4mim]Cl and inorganic salt above a certain critical concentration (Safavi et al., 2008). He et al. (2005) used [C4mim]Cl to separate testosterone and epitestosterone from an aqueous solution. Other works based on ionic liquids and water-structuring salts have been reported (e.g., protein extraction with a series of ionic liquids, by Pei et al. (2009)). Vijayaraghavan et al. (2006) used N-butyl, N-methyl pyrrolidinium bis (trifluoromethanesulfonyl) amide to extract azo dye from water. The initial extraction efficiency was about 50%, while, with two or three extraction stages, it easily reached 95%. Li et al. (2007) investigated acid dye extrac- tions from aqueous solutions using 1-butyl-3-methylimidazolium hexafluoropho- sphate ([C4mim]PF6); the ion exchange process was predominant for extraction of dyes and obviously responsible for the high distribution constant.
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Tuning the colloidal stability in ionic liquids by controlling the nanoparticles/liquid interface

Tuning the colloidal stability in ionic liquids by controlling the nanoparticles/liquid interface

Ionic liquids (ILs) are a novel class of solvents constituted solely of ions, with melting points below 100 °C. Although known for a long time, ILs have been attracting a great deal of interest in recent years due to some specific properties, such as non- flammability, negligible vapor tension and high thermal stability, to name a few. ILs are then promising “green” candidates that could replace classical and more dangerous organic solvents as reaction media in many fields, such as chemical organic and inorganic synthesis, enzyme-catalyzed reactions, or for the preparation of magneto-rheological fluids, lubricants and electrochemical devices. 1
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Correlation between thermostability and stability of glycosidases in ionic liquid

Correlation between thermostability and stability of glycosidases in ionic liquid

Kaftzik N, Wasserscheid P, Kragl U (2002) Use of Ionic Liquids to Increase the Yield and Enzyme Stability in the -Galactosidase Catalyzed Synthesis of N-Acetyllactosamine. Org Process Res Dev 6:553-557 Kamiya N, Matsushita Y, Hanaki M, Nakashima K, Narita M, Goto M, Takahashi H (2008) Enzymatic in situ saccharification of cellulose in aqueous-ionic liquid media. Biotechnol Lett 30:1037-1040

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Capacitance of Ti3C2Tx MXene in ionic liquid electrolyte

Capacitance of Ti3C2Tx MXene in ionic liquid electrolyte

[5e10] and supercapacitors [1,11e13] where high volumetric capacitance up to 900 F cm "3 was reported in aqueous electrolyte for the latter [1] . However, when a colloidal solution of MXene flakes is filtered for MXene paper electrode preparation, they restack and once the film was completely dried, the c-lattice parameter dropped dramatically. In other words, their interlayer spacing becomes smaller and this process was irreversible [14] . MXene flakes' restacking during filtration and their small interlayer spacing limit the accessibility to electrolyte ions, especially the large ions of ionic liquids, hindering the full utilization of the sur- face area thus leading to poor electrochemical behavior [15] . Improvement has been made by adding carbon nanotubes or gra- phene materials to MXene [15,16] and making composite materials, which also enhanced the capacitance of MXene-based super- capacitors in organic electrolytes [17] . However, the use of pure MXenes in ionic liquid electrolytes has not been reported yet. Ionic liquids (ILs) are solvent-free salts that are liquid at room temper- ature. They are promising for energy storage devices due to their
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TTA solvation kinetics in the ionic liquid Bumim$Tf_2N$

TTA solvation kinetics in the ionic liquid Bumim$Tf_2N$

Ionic liquids (ILs), although known for a long time, have appeared only recently as potential “green” solvents in all fields of chemistry, in replacement of those traditional organic phases for which generation of volatile organic compounds is nowadays considered as a critical issue [1]. They display tunable properties, as a consequence of their variable chemical structure and some ILs properties can be very different from those of usual organic solvents. In particular, ILs possess the almost unique advantage to dissolve both neutral and charged entities, allowing rather uncommon chemistry to occur. So far, the understanding of solvation mechanism in ILs is still in its infancy, which in turn limits their use. In the field of radiochemistry, ILs have already demonstrated their potential as An/Ln organic extracting phases [2-5] and as practical electrodeposition media [6-8]. Many papers have highlighted some of the very specific properties of ILs, that may open new routes for separation/partitioning of An/Ln but very few works have focussed yet on the problems that can arise from the relatively high viscosity most of them display. Actually, large viscosity is usually associated with slow kinetics, that would hamper the development of ILs as solvents. In the present work, we take advantage of the keto-hydrate/enol equilibrium kinetics of thenoyltrifluoroacetone (TTA) dissolved in 1-butyl-3-methyl-imidazolium bistriflimide (BumimTf 2 N), to demonstrate that although viscous, BumimTf 2 N displays kinetics that is
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Capacitance of Ti3C2Tx MXene in ionic liquid electrolyte

Capacitance of Ti3C2Tx MXene in ionic liquid electrolyte

[5e10] and supercapacitors [1,11e13] where high volumetric capacitance up to 900 F cm "3 was reported in aqueous electrolyte for the latter [1] . However, when a colloidal solution of MXene flakes is filtered for MXene paper electrode preparation, they restack and once the film was completely dried, the c-lattice parameter dropped dramatically. In other words, their interlayer spacing becomes smaller and this process was irreversible [14] . MXene flakes' restacking during filtration and their small interlayer spacing limit the accessibility to electrolyte ions, especially the large ions of ionic liquids, hindering the full utilization of the sur- face area thus leading to poor electrochemical behavior [15] . Improvement has been made by adding carbon nanotubes or gra- phene materials to MXene [15,16] and making composite materials, which also enhanced the capacitance of MXene-based super- capacitors in organic electrolytes [17] . However, the use of pure MXenes in ionic liquid electrolytes has not been reported yet. Ionic liquids (ILs) are solvent-free salts that are liquid at room temper- ature. They are promising for energy storage devices due to their * Corresponding author. CIRIMAT, Universit!e de Toulouse, CNRS, INPT, UPS, 118,
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Experimental characterization of single droplets size and composition in liquid- liquid extraction systems with rainbow diffractometry

Experimental characterization of single droplets size and composition in liquid- liquid extraction systems with rainbow diffractometry

0.8% in mass fraction of Marcol in hydrogenated tetrapropylene) can be achieved. These results open up perspectives for liquidliquid extraction studies and more generally, mixing studies in two-phase flows. 1. Introduction Liquidliquid extraction, designed for selective separation of products in a mixture by solvent extraction, is a key process in chemical engineering. When applied in nuclear fuel reprocessing, two immiscible liquids are contacted: an aqueous phase and an organic phase. Only one phase, the continuous or the dispersed one, contains an extractant molecule capable of transferring the desired radioactive element from one phase to the other. After the transfer in a contactor such as a mixer–settler, an agitated or a pulsed column, both phases are separated by settling. To better understand the key factors and thus enhance the efficiency of the whole process, the experimental analysis of the kinetics of extraction and the interfacial area is a major issue, e.g. Lamadie et al. (2012). This requires in particular the determination of the size distribution and composition of the dispersed phase (i.e. in the present study, droplets with a low relative refractive index m≈1.06-1.23, the latter being used to infer the droplet composition).
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NMR Study of Ion Dynamics and Charge Storage in Ionic Liquid Supercapacitors

NMR Study of Ion Dynamics and Charge Storage in Ionic Liquid Supercapacitors

In principle, the observed line width changes can be directly correlated with the rate of motion. Extraction of accurate exchange rates, however, requires (i) an estimate of the line shape in the absence of ionic motion and (ii) a model for ionic motion in the highly heterogeneous carbon pore structure. While NICS calculations on model carbon fragments 38 can be used to estimate the range of possible shifts for adsorbed ions, the treatment of (ii) is not trivial since we do not know the distances and pathways between sites with di fferent chemical shifts. We explored this issue in our recent lattice model calculations, which highlight the sensitivity of the observed line shapes to the spatial distribution of adsorption sites within a carbon particle. 65 In the absence of an accurate model for the micro- and macroscopic structure of this activated carbon, we developed a simple multisite exchange model to investigate the time scales required to reproduce the experimental line widths (see Supporting Information) and obtain order-of-magnitude estimates for the motion. In this approach we use the distribution of chemical shifts calculated in our prior NICS calculations 38 on model carbon fragments to provide an estimate for the range of possible shifts and compute the e ffect of random jumps between the various sites on the NMR line shapes. Our simulations suggest that the di ffusive motion of in- pore TFSI − between di fferent adsorption sites in the carbon pores is thermally activated, with an activation barrier on the order of 10 kJ·mol −1 . Our calculated time scales for this motion
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Probing the local structure of pure ionic liquid salts with solid- and liquid-state NMR

Probing the local structure of pure ionic liquid salts with solid- and liquid-state NMR

Ionic liquids (ILs) have been known for nearly a century [1] but initially there was little interest in investigating their use as sol- vents. The term “room-temperature ionic liquids” (RTILs) is often used interchangeably with “ionic liquidsand is loosely defined as those ILs that have melting points at around or below 100 8C. Their low volatility has made them attractive tar- gets as substitutes for volatile organic solvents. A broad spec- trum of tunable properties arises from the customizability of the organic cation and the variety of cation–anion pairings and so ILs are often denoted as “designer solvents”. Ionic liquids are finding uses as solvents and reaction media in a large number of diverse applications such as carbon dioxide sen- sors, [2] catalysis, [3, 4] energy storage, [5] nanostructure synthesis, [6, 7]
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Structural Transitions at Ionic Liquid Interfaces

Structural Transitions at Ionic Liquid Interfaces

The variety of systems in which transitions are observed clearly show that it is a common feature of metal −ionic liquids interfaces. However, the few works reported so far raise very interesting questions. In particular, all the ordered structures proposed to interpret the STM data are composed of a single species only. Nevertheless, the relatively small applied potentials which are used ( ∼ ± 1 V) may not be sufficient to fully separate cations from anions. In the case of the AFM study, the anion −cation−cation−anion rows result in an overall neutral layer, but there is a strong charge imbalance on the nanometer scale. A few hypotheses can thus be proposed to explain the observations: (i) there may be a speci fic adsorption of the ions on gold with the formation of partially covalent bonds; 33 (ii) on top of the observed layer, there could be an oppositely charged layer of ions which is not observed by the experiment; and (iii) it remains possible that the proposed structures, which are based on only the relative size of the ions (keeping the possibility of some kind of conformational ordering, for example only the imidazolium rings of the cations would lie parallel to the surface), are not the correct ones. Using additional techniques such as SFG, which is sensitive to the orientation of the ions, 4 could possibly shed a complementary light on this issue. Another open question is whether commensurability between the adsorbed layer and the metal substrate is necessary to observe a transition. Here also, the recent study performed with HOPG electrodes 32 suggests that it is not the case, and that the electric fluctuations at a homogeneous and flat metallic surface are sufficient to trigger ordering transitions in the interfacial layer of RTIL. In addition, the use of carbon electrodes in this study demonstrates that a perfect metallic behavior is not necessary to induce such transitions.
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NMR Study of Ion Dynamics and Charge Storage in Ionic Liquid Supercapacitors

NMR Study of Ion Dynamics and Charge Storage in Ionic Liquid Supercapacitors

In principle, the observed line width changes can be directly correlated with the rate of motion. Extraction of accurate exchange rates, however, requires (i) an estimate of the line shape in the absence of ionic motion and (ii) a model for ionic motion in the highly heterogeneous carbon pore structure. While NICS calculations on model carbon fragments 38 can be used to estimate the range of possible shifts for adsorbed ions, the treatment of (ii) is not trivial since we do not know the distances and pathways between sites with different chemical shifts. We explored this issue in our recent lattice model calculations, which highlight the sensitivity of the observed line shapes to the spatial distribution of adsorption sites within a carbon particle. 65 In the absence of an accurate model for the micro- and macroscopic structure of this activated carbon, we developed a simple multisite exchange model to investigate the time scales required to reproduce the experimental line widths (see Supporting Information) and obtain order-of-magnitude estimates for the motion. In this approach we use the distribution of chemical shifts calculated in our prior NICS calculations 38 on model carbon fragments to provide an estimate for the range of possible shifts and compute the effect of random jumps between the various sites on the NMR line shapes. Our simulations suggest that the diffusive motion of in- pore TFSI − between different adsorption sites in the carbon pores is thermally activated, with an activation barrier on the order of 10 kJ·mol −1 . Our calculated time scales for this motion (i.e., for random hops between the sites that give rise to the broadened line shape) vary on the order of ∼20−130 μs depending on the temperature (344−252 K) and the ionic liquid studied. At all temperatures studied, the time scale for in- pore TFSI − motion is faster for EMITFSI than for Pyr
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Design, Development and Testing of Miniature Liquid-liquid Extraction Contactors for R&D Studies in Nuclear Environment

Design, Development and Testing of Miniature Liquid-liquid Extraction Contactors for R&D Studies in Nuclear Environment

HAL Id: cea-02197141 https://hal-cea.archives-ouvertes.fr/cea-02197141 Submitted on 30 Jul 2019 HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

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Development and validation of a multi-residue method for pesticide determination in honey using on-column liquid-liquid extraction and liquid chromatography-tandem mass spectrometry

Development and validation of a multi-residue method for pesticide determination in honey using on-column liquid-liquid extraction and liquid chromatography-tandem mass spectrometry

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran, Methiocarb, Pirimicarb, Dimethoate, Fipronil, Imidacloprid; herbicides: Amidosulfuron, Rimsulfuron, Atrazine, Simazine, Chloroturon, Linuron, Isoxaflutole, Metosulam; fungicides: Diethofencarb) and 2 metabolites (Methiocarb sulfoxide and 2-Hydroxytertbutylazine) in honey. This method is based on an on-column liquid-liquid extraction (OCLLE) using diatomaceous earth as inert solid support and liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS). Method specificity is ensured by checking retention time and theoretical ratio between two transitions from a single precursor ion. Linearity is demonstrated all along the range of concentration that was investigated, from 0.1 to 20 ngg -1 raw honey, with correlation coefficients ranging from 0.921 to 0.999, depending on chemicals. Recovery rates obtained on home-made quality control samples are between 71 and 90%, well above the range defined by the EC/657/2002 document, but in the range we had fixed to ensure proper quantification, as levels found in real samples could not be corrected for recovery rates. Reproducibility is found to be between 8 and 27%. Calculated CCα and CCβ (0.0002-0.943 ngg -1 for CCα, and 0.0002-1.232 ngg -1 for CCβ) show the good sensitivity attained by this multi-residue analytical method. The robustness of the method has been tested in analyzing more than 100 raw honey samples collected from different areas in Belgium, as well as some wax and bee samples, with a slightly adapted procedure.
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Graphene-Based Supercapacitors Using Eutectic Ionic Liquid Mixture Electrolyte

Graphene-Based Supercapacitors Using Eutectic Ionic Liquid Mixture Electrolyte

within a large working temperature window. Conductivity values of 28.9 mS/cm and 4.9 mS/cm were measured at 100 and 20 ! C, respectively, as reported earlier [23] . In this paper, we propose to use a densified graphene electrode such as proposed by Li’s group [7] . in combination with an ionic liquid eutectic mixture as electrolyte to improve both the voltage

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