Ionic Liquid Media Research Articles

Active γ –Alumina -Supported Ru Nanoparticles for CO2 Hydrogenation Reaction

A series of alumina supported Ru nanoparticles (Ru γ -Al2O3-x (x=2-10 Ru wt%) was synthesized using the ethylene glycol reduction method. XRD, TEM, EDX, H2-chemisorption, XPS and H2-TPD analytical techniques were used to understand the physiochemical nature of alumina supported Ru nanoparticles. All the well-characterized Ru#Al2O3-x (x=2-10 Ru wt%) catalysts were used for high-pressure CO2 hydrogenation to formic acid synthesis. A clear correlation was recorded between the physiochemical properties of developed catalysts and the molar quantity of formic acid. Among all the developed catalysts, Ru#Al2O3-2 catalyst with or without ionic liquid reaction medium gave a good molar quantity of formic acid. Application of ionic liquid was also expanded, and ionic liquid medium appeared as a good solvent system as compared to the amine solvent system, which not only provides better solubility of reactants and catalysts but also found useful in the easy recovery of formic acid after the completion of the reaction. The catalyst recycled seven times with easy product isolation stem to make this system very useful and fulfill the requirement of sustainable chemistry.

Selective and sensitive determination of dihydroxybenzene isomers in water samples using functionalized copper nanoparticles modified graphite electrode

A highly selective and sensitive electrochemical sensor for the determination of environmentally hazardous dihydroxybenzene isomers such as hydroquinone (HQ), catechol (CC) and resorcinol (RS) was fabricated by electrodeposition of Cu nanoparticles on polycysteine film deposited graphite electrode in room temperature ionic liquid medium as electrolyte. The electrochemical characteristics of the polycysteine functionalized copper nanoparticles (PCFCuNP) modified electrode was studied using cyclic voltammetry. The voltammetric response of dihydroxybenzene isomers at the modified electrode showed the current densities remarkably higher than the bare graphite electrode and occurred at a reduced overvoltage. For HQ, CC, RS the oxidation peak currents are linear to the concentrations at the range of 3.3 × 10-6 − 1.3 × 10-3 M, 1.6 × 10-6 −1.3 × 10-3 M and 3.3 × 10-6 − 9.0 × 10-3 M with the detection limits of 1.1 × 10-6 M, 5.3 × 10-7 M and 1.1 × 10-6 M, respectively (S/N = 3). The stable and fast response during amperometric method shows the potential application of the PCFCuNP modified electrode for flow system analysis. The method was successfully examined for two different water samples with high selectivity and sensitivity.

Experimental and theoretical insight into the extraction mechanism, kinetics, thermodynamics, complexation and radiolytic stability of novel calix crown ether in ionic liquid with Sr2+

A comparative evaluation was carried out for the extraction of Sr2+ using novel calix crown ether in molecular diluent and in ionic liquid. Though the trend in extraction profiles was found to be similar for both the systems, still, almost 5 times higher distribution ratio (D) values were observed in ionic liquid. The speciation studies revealed that; neutral Sr (NO3)2. DHCC species was formed in dodecane and the extraction followed through ‘solvation’ mechanism. However, ionic liquid medium (IL), anionic species, [Sr(NO3)3. DHCC]− was found to be predominating indicating ‘anion exchange’ mechanism. The slower kinetics of extraction in IL was attributed to the high viscosity of IL. The extraction process was found to be spontaneous, endothermic and entropy driven.IL based system was found to be radiolytically more stable compared to the molecular diluent (Mol dil) based system. The electron paramagnetic resonance (EPR) spectroscopic investigation revealed the formation of oxygen centered radical with orthorhombic symmetry (gx = 2.00105, gy = 2.00475, gz = 2.00835) in irradiated ligand. The density functional theoretical (DFT) calculation was utilized to investigate the complexation and speciation in detail in microscopic level.

Electrodeposition of Stoichiometric CdTe from a Reusable Ionic Liquid Bath

Electrodeposition (ED) from ionic liquid (IL) medium is of much importance due to a variety of architectures can be synthesized by IL assisted growth. However, these liquids are relatively new for the fabrication of compounds and alloys with a great control over the stoichiometry and thickness. In this article, we have discussed the prerequisites and a detailed methodology to develop stoichiometric CdTe thin films from IL medium with required thicknesses in a controlled way. We have found that the required precursor ratio of Te:Cd can be lower down to 1:10 for 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) IL which is usually 1:1000 for the aqueous electrolytes. Moreover, the aspect ratio of nanostructures can be tuned by changing the precursors’ ratio in IL bath. Nevertheless, IL can be reused multiple times to develop identical thin films which guarantee green and low cost pathway.

Synthesis and characterization of nanocellulose using renewable resources through Ionic liquid medium

Wood and agricultural bio-residues are the main natural sources of cellulose available on the earth. Cellulose is the world’s most abundant biopolymer in nature and possesses properties such as low cost, high strength, good biocompatibility and good thermal stability by chemical treatment. In the present work, nanocellulose was obtained from native rubber wood powder, maize husk and sugar cane bagasse. Cellulose was obtained after bleaching with sodium chlorite and alkali treatment by NaOH to remove lignin and hemicellulose. Obtained cellulose is treated with ionic liquid (1-butyl-3-methylimidazolium chloride ([Bmim] Cl)) solvent. The chemical functionality and its characterisation were observed by FTIR, XRD, TGA/DTA, SEM and TEM. FTIR spectra reveal the functional groups and significant conversion of cellulose to nanocellulose. XRD exhibits the crystalline or semicrystalline nature. TGA/DTA showed the thermal stability. SEM and TEM monographs depict the surface topology and size of the nanocellulose.

Facile production of cellulosic organic solutions and organogels from ionic liquid media

In this study, we investigate what types of cellulosic materials are formed by soaking the cellulose/ionic liquid (1-butyl-3-methylimidazolium chloride, BMIMCl) solutions in various organic liquids. When the 5-wt% cellulose/BMIMCl solutions were soaked in organic liquids with high and moderate polarities (relative permittivities), the corresponding cellulosic solutions and gels were produced, respectively. On the other hand, soaking the cellulose/BMIMCl solutions in lower polar liquids resulted in aggregation of cellulose in the mixtures. As the gels with high boiling point media were stable, they were characterized by viscoelastic and compression measurements. Contents of organic media and BMIMCl in the gels were changed depending on the polarities, which affected the mechanical properties under compression mode. Furthermore, processes for production of the solution, gel, and aggregate were proposed.

Catalyst-free Synthesis of Mono and Bis Spiro Pyrazolopyridines in DSDABCO as a Novel Media

In this work, multicomponent synthesis of mono and bis spiro-pyrazolopyridines from isatin derivatives, indanedione and 3-methyl-5-aminopyrazole at the presence of 1,4-disulfo-1,4-diazoniabicyclo[2.2.2]octane chloride (DSDABCO) as a novel ionic liquid media is reported. The present methodology offers several advantages such as simple procedure, mild conditions, excellent yields, green media and reduced environmental consequences. The ionic liquid was recovered and reused. The structures of the synthesized spiro-pyrazolopyridine compounds were confirmed by 1H, 13C NMR and FTIR spectral data and elemental analyses.

Growth and cycling of polyaniline electrode in a deep eutectic solvent: A new electrolyte for supercapacitor applications

Polyaniline electrode on a graphite substrate was produced and evaluated for use in an ionic liquid electrolyte for supercapacitor applications. The aniline monomers were added in Ethaline deep eutectic solvent electrolyte. The deep eutectic solvent is a type of ionic liquid consisting of only ions without water. Aniline was polymerized electrochemically onto graphite current collector from a non-aqueous and non-acidic Ethaline electrolyte. Polyaniline film obtained in Ethaline had homogenous agglomerated nanoparticles. Growth of polyaniline was not autocatalytic reaction in ionic liquid media and the rate of its growth slowed down upon increasing time. Electropolymerized polyaniline was transferred in two different electrolytes (acetonitrile containing LiCIO4 solution and monomer-free Ethaline) to determine the electrochemical properties of the polyaniline coated graphite electrodes by cyclic voltammetry and galvanostatic charge-discharge techniques. The capacitance of the modified electrode retains 87% of its initial value after 10,000 cycles in Ethaline electrolyte because the polyaniline electrode was probably not effected from swelling and shrinking in an anhydrous ionic liquid for long cycles. The electrode deposited from Ethaline ionic liquid medium and cycled in pure Ethaline electrolyte had a specific capacitance of 833 F g−1 at 20 mV s−1 scan rate. The polyaniline coated graphite electrode electrodeposited using one-step polymerization in Ethaline media is a promising electrode for high-performance supercapacitors that can be used in non-aqueous electrolytes.

Synergic extraction of europium(III) in hydrophobic ammonium ionic liquid containing neutral and acidic extractants

The extraction behavior of europium(III) in a binary solution containing octylphenyl(N,N-diisobutylcarbamoylmethyl) phosphine oxide (CMPO) and bis-2-(2-ethylhexyl)phosphoric acid (D2EHPA) in ionic liquid medium has been reported in this paper. Methyltrioctylammonium bis(trifluoromethanesulfonyl)imide ([N1888][NTf2]) was used as ionic liquid diluent in the present study. The extraction of europium(III) was investigated as a function of various parameters, such as aqueous phase acidity, extractant concentration, equilibration time and the experimental temperature. The extraction of Eu(III) in CMPO in [N1888][NTf2] and D2EHPA in [N1888][NTf2] was studied to compare the extraction data with those obtained in a binary solution. The stripping behavior of Eu(III) from the loaded ionic liquid phase was also investigated.

An overview of molecular extractants in room temperature ionic liquids and task specific ionic liquids for the partitioning of actinides/lanthanides

Solvent extraction process is applied for the extraction of actinides/lanthanides from waste water produced in nuclear industry. Various extractants have been developed for this purpose. More recently separation scientists have shown extensive interest toward ionic liquids (ILs) due to their unique properties. ILs have extensively been used as extraction medium for the recovery of rare earths and actinides or modified to task specific ionic liquids (TSILs); where ionic liquid part has been covalently attached to the extractants. This article highlights some conventional extractants, the use of these extractants in IL medium and the development of TSILs. The effect of medium on extraction efficiency has also been discussed.

Biogenic approach for the synthesis of Ag-Au doped RuO2 nanoparticles in BMIM-PF6 ionic liquid medium: Structural characterization and its biocidal activity against pathogenic bacteria and HeLa cancerous cells

In the present work, we focused on the eco-friendly and greener approach to the synthesis of silver–gold/ruthenium oxide (Ag-Au/RuO2) nanoparticles (NPs) using ethanolic leaf extracts of Justicia adhatoda with ionic liquid (IL) by the hydrothermal method. The 1-butyl-3-methylimidazolium hexafluorophosphate IL was used to control the particle growth during the synthesis of nanoparticles (NPs). The Justicia adhatoda leaves extracts contains vasicinone and N, N-Dimethylglycine which behaves capping and reducing agent. The synthesized NPs were characterized by different physicochemical analysis to confirm its formation. The average crystallite size of Ag-Au/RuO2 NP is 24 nm, as found from the X-ray diffraction results. Fourier transform infrared spectrum confirmed the RuO peak at the range of 476 cm−1. The optical band gap of Ag-Au/RuO2 NP is 2.98 eV, it is confirmed by ultraviolet- diffuse reflectance spectrum result. SEM analysis of Ag-Au/RuO2 nanoparticle has a spherical like the structure of surface morphology. Energy-dispersive X-ray spectroscopy showed the composition of ruthenium, silver, gold, and oxygen present in the synthesized NPs. Ag–Au/RuO2 NPs revealed outstanding antibacterial activity against Escherichia coli and Staphylococcus aureus microbes. Furthermore, Ag–Au/RuO2 NPs exposed good anticancer properties against HeLa cancerous cell line. From the above results suggested Ag–Au/RuO2 NPs can be used in various applications in the biomedical field.

Electrodeposition of Stoichiometric CdTe from a Reusable Ionic Liquid Bath

Electrodeposition (ED) from ionic liquid (IL) medium is of much importance because a variety of architectures can be synthesized by IL assisted growth. However, these liquids are relatively new for the fabrication of compounds and alloys with a great control over the stoichiometry and thickness. In this regard a well-defined route needs to be established for their wider acceptance as greener alternatives to deposit materials like CdTe, CdS, CdSe, etc. via ED. In this article, we have discussed the prerequisites, tricks and methodology to develop stoichiometric CdTe thin films from IL medium with required thicknesses in a highly controlled way compared to conventional ED techniques. This method provides a greener alternative to aqueous electrolytes which are considered to be hazardous media for the ED of CdTe films. We have found that the required precursor ratio of Te:Cd can be lower down to 1:10 for [Bmim]Cl IL medium which is 1:1000 for the aqueous electrolytes. As-grown nanostructured CdTe films can be directly utilized for the devices like IR sensors, Schottky rectifiers and Solar cells without any post-annealing. Moreover, the aspect ratio of nanostructures can be tuned by changing the precursors’ ratio in IL bath. Nevertheless, IL can be reused multiple times to develop identical thin films which guarantee the low cost pathway.

(Invited) Controlling Free Charge Density Gradients in Ionic Liquid Media

Room Temperature Ionic Liquids (RTILs) have found use in a variety of practical applications, including chemical synthesis and supercapacitor development, but many fundamental issues remain to be resolved in understanding dynamics, organization and the response of these materials to external forces. We have demonstrated that RTILs in contact with a charged surface can exhibit a free charge density gradient (ρf ) that extends over ca. 100 μm. The existence of such a free charge density gradient in a fluid medium is without precedent and needs to be understood. Experimental and theoretical investigations of RTILs have revealed organization of some type over a variety of length scales, ranging from ca. 10 nm to ca. 100 μm. The term “organization” is not well-defined, however. The existence of any type of organization over such a range of length scales is highly unusual for a liquid, particularly so for a macroscopic free charge density gradient in an ionic liquid. Achieving a deeper understanding of this phenomenon is important because of its implications in how we conceptualize and use this class of materials.We report on experiments that have elucidated the spatial extent of the induced gradient, it's magnitude, and the chemical and structural factors that serve to determine these factors. We also present a model for understanding this gradient that draws on known physical properties of materials such as piezoelectrics. The optical and physical behavior of RTILs draw analogy to piezoelectric properties in solids and the demonstration of this correspondence provides a novel framework for the interpretation of the unexpected phenomena we have reported.

Selective separation of zirconium(IV) from uranium(VI) using dioxoamide ligand present in ammonium based ionic liquid: An application towards spent metallic fuel reprocessing

The alloy of an actinide (U or Pu) with zirconium (6%) has been proposed as metallic fuel. The removal of zirconium from the dissolver solution is required prior to the separation of actinides during reprocessing. In this context, the extraction behavior of zirconium was studied in a solution of 2-ethylhexyl- and the decyl-derivative of benzodioxodiamide, abbreviated as BD and BDD, respectively, in ionic liquid medium. Instead of the conventional imidazolium ionic liquid that displayed several drawbacks, strongly hydrophobic ionic liquids such as methyltributylammonium bis(trifluoromethylsulfonyl)imide ([N1444][NTf2]) and methyltrioctylammonium bis(trifluoro-methylsulfonyl)imide ([N1888][NTf2]) have been employed, as a diluent, in conjunction with the BD and BDD ligands for the extraction of Zr(IV). The effect of nitric acid concentration in aqueous phase, duration of equilibration, interference of uranium and the effect of temperature on the extraction of Zr(IV) in BD present in ionic liquid was studied. The number of BD-ligands involved in the extraction of zirconium was determined. The results showed the possibility of removing zirconium from the bulk quantity of uranium present in the dissolver solution.

Electrochemical Fabrication of Copper and Tin Micro‐Crystals from a Protic Ionic Liquid Medium

AbstractNew protic ionic liquid, namely 1‐Methylpiperidinium trifluoromethane sulphonate [HmPip][OTf] was synthesized and employed for the dissolution of Cu and Sn metal precursors followed by the electrodeposition process of the subsequent metals. The cyclic voltammogram of [HmPip][OTf], CuCl2 (80 mM) in [HmPip][OTf] and SnCl2 (65 mM) in [HmPip][OTf] phase recorded at glassy carbon electrode (working electrode), with the glassy carbon as counter and platinum as the reference electrode. The CV indicates that Cu2+ underwent two‐step one‐electron transfer, whereas Sn2+ reduced via one step two‐electron transfer. The diffusion coefficient of Cu1+, Cu2+ and Sn2+ ions in [HmPip][OTf] phase were evaluated by the CV method. The experimental temperature and the scan rate were set at 353 K and 110 mV/s respectively. Electrodeposition of Cu and Sn was done at their corresponding reduction potential determined from cyclic voltammetry. Spectroscopic investigation of the deposits obtained after electrodeposition is done by SEM‐EDX as well as XRD.

Preparation and Characterization of the Sol-Gel Silica Containing Ionic Liquids as a Potential Adsorbent for the Removal of Cr(VI) Ions from Aqueous Solutions

In this study ionic liquid mediated sol-gel silica adsorbents were prepared and characterized to investigate the sorption of Cr (VI) ions from aqueous solutions. For this purpose silica based adsorbents containing ionic liquids (ILs) were synthesized by following the sol-gel method in ionic liquid media. Thus the high extracting ability of ILs were combined with the surface properties of silica substances. Commercial (Aliquat 336® and EMIMTf2N) and synthesized ([A336][NO3]) ionic liquids were incorporated directly by sol-gel process. Silica based adsorbents were being initiated with silica precursor (TEOS), water, alcohol and ionic liquid hydrolysis in the presence of an acid catalyst then completed with a condensation reaction. Chemical and morphological characterization of prepared adsorbents have been investigated by FTIR, SEM and BET analysis. The materials exhibited average pore diameter of 2 nm, pore volume of 0.3 cm3/g and BET surface area of 300–600 m2/g. The sorption behaviors of adsorbents have been investigated by using a series of batch sorption studies. Cr(VI) sorption percentages of the adsorbents were enhanced by containing ILs up to 99% with the adsorption capacity of 31.74 mg/g. It can be concluded that sorption of Cr(VI) ions from aqueous solution by sol-gel silica based adsorbents containing Aliquat 336 takes place favorably and these type of adsorbents are promising agents in the adsorption processes.

Influence of Concentration of Precursors and Solvent on the Size of Zinc Sulfide Nanoparticles Produced in Ionic Liquid Medium

A method was proposed for producing ZnS semiconductor nanoparticles: “quantum dots” in an ionic liquid medium, N-decylpyridinium tetrafluoroborate. The average nanoparticle sizes were determined by UV spectroscopy, dynamic light scattering, and probe microscopy. It is shown that a high threshold concentration of nanoparticles is reached in the ionic liquid medium, an increase in the concentration of precursors in the reaction mixture leads to an increase in the average size of nanoparticles. Ultrasonic treatment helps to reduce the polydispersity of sols and results in the formation of stable sols with a higher concentration of nanoparticles.

Ionic liquids with fluorine-containing anions as a new class of functional materials: features of the synthesis, physicochemical properties, and use

The results obtained by the authors and literature data on the methods of preparation, properties, and the use of ionic liquids with fluorine-containing anions are reviewed. The dependences of the physicochemical and hydrodynamic properties of the ionic liquids on the structure of the anionic fragment, interactions between the cation and anion, and inter molecular interactions in a ionic liquid medium are considered. The effects of the ionic liquid structure on the solubility of gaseous substance in it and on the mutual solubility of the ionic liquid, water, and organic compounds are analyzed.

Transferring photocatalytic CO2 reduction mediated by Cu(N^N)(P^P)+ complexes from organic solvents into ionic liquid media

Photocatalytic carbon dioxide reduction utilizing metal complexes based on the earth-abundant transition metals iron and copper was transferred from organic solvents into ionic liquids with high selectivity and moderate turn-over numbers.

Magnetic Organic-Inorganic Hybrid Nano System Anchored Platinum Nanoparticles for Carbon Sequestration Reaction

new Pt metal based nano-catalytic system was developed using organic-inorganic magnetic framework followed by the user-friendly protocol in good yield. XRD, FTIR, TEM, BET, ICP-OES and solid-state NMR techniques were used to characterize our developed catalytic system. The wellcharacterized ionic liquid bridged-silica supported magnetic Pt nanoparticles were utilized for the selective hydrogenation of carbon dioxide under high-pressure reaction condition (with and without ionic liquid medium). Most promising results were obtained while using the catalytic system (Pt-MagNP@ILSiO2) in 1,3-di (N, N-dimethylaminoethyl)-2-methylimidazolium nonafluorobutanesulfonate ([DAMI] [CF3CF2CF2CF2SO3]) task-specific ionic liquid medium. This TSIL not only provided a high degree of CO2 absorption during the reaction but also enhances the selectivity and the recyclability of the catalytic system up to 8 runs. No sign of Pt metal leaching was recorded during the recyclability test which confirmed the stability of this catalytic system under high-pressure reaction condition.