BMIM BF4 Research Articles

Experimental and theoretical study of optical properties of pyrromethene (PM‐597) laser dye in binary eco‐friendly solvent

AbstractThe interaction of pyrromethene (PM‐597) laser dye with binary mixture of [1‐butyl‐3‐methylimidazolium tetrafluoro‐borate (BMIM BF4)] ionic liquid with water [BMIM BF4: H2O] as binary eco‐friendly solvent, were investigated experimentally and theoretically by means of photophysical properties, amplified spontaneous emission (ASE), photostability, electronic ground state of molecular structures of PM‐597, BMIM BF4 and mixture of (PM‐597/BMIM BF4) using the density functional theory (DFT) technique, molecular orbitals, energy gap (Eg) among HOMO and LUMO, and the maps of molecular electrostatic potential (MESP) for PM‐597 and mixture of (PM‐597/BMIM BF4) in gas phase were calculated using B3LYP/6‐31G(d) level of theory. The refractive index (nD) and density (ρ) values for binary mixes of ionic liquid with water [BMIM BF4: H2O] with different ratios, increases as molecular mass of ionic liquid (BMIM BF4) in water increases. The frequency doubling Nd‐YAG laser of 532 nm was used to investigate amplified spontaneous emission (ASE). Aside from that, the efficiency of energy conversion was explored. Efficiency is relatively high, and 20.6% was achieved, with good photostability in case of 5 × 10−4 mol/L of PM‐597 in binary mixture of [90% BMIM BF4: 10% H2O] that was a decrease to ~48.3% of the initial amplified spontaneous emission, this output energy was observed after pumping by 72,000 shots at relatively high repetition rate (10 Hz) and pumping energy (40 mJ). In this research, we had used the mixture of [(BMIM BF4: H2O] with different ratios, as binary eco‐friendly solvent instead of harmful organic solvents.

Tribological performance of phosphonium-based halogen-free ionic liquids as lubricant additives

In recent years, ionic liquids have shown great potential as an additive in lubricants. However, most of the explored ionic liquids for machining applications contain halogen-based anions, which are sensitive to moisture and have a tendency to produce harmful halogen acids (HX) after reacting with water/moisture. These acids are harmful to the environment and can corrode the working surfaces. This study investigates the effectiveness of halogen-free ionic liquids as potential additives to vegetable oil (canola oil). Two halogen-based ionic liquids (1-methyl 3-butylimidazolium tetrafluoroborate [BMIM BF4] and 1-methyl 3-butylimidazolium hexafluorophosphate [BMIM PF6]) and one halogen-free ionic liquids (trihexyl tetradecyl phosphonium bis (24,4-trimethylpentyl) phosphinate P6,6,6,14 [i(C8)2PO2]) were blended individually with canola oil. The percentage ratio of ionic liquid to canola oil is 1:99. Dynamic viscosity and contact angles of different lubricants were measured. Sliding tests were conducted in various conditions; dry, canola oil, and three different blends of ionic liquid with canola oil. Further, to connect tool-chip tribology with machining, turning experiments were carried out under similar lubricating conditions. Results show that the sliding friction, pin surface temperature, and wear were reduced by 48.1%, 44%, and 69.6%, respectively, due to better lubricating ability and spreading tendency of halogen-free ionic liquid blended with canola oil. The microscopic analyses of pin surfaces and the morphology of counter disc surfaces further supported better lubrication between the sliding pair. For P6,6,6,14 [i(C8)2PO2] ionic liquid blended with canola oil, the average cutting temperature and machined workpiece surface roughness reduces by 43.6% and 62.4% compared to dry machining.

Green synthesis of ionic liquid mediated neodymium oxide nanoparticles via Couroupita guianensis abul leaves extract with its biological applications

Bio-nanoparticles have created a new era of rapid, harmless and nontoxic drugs for various biomedical applications. The nanoparticles (NPs) of rare earth metal oxides attract researcher’s attention due to their excellent chemical and physical properties that exhibit potential activity against disease causing pathogens. Couroupita guianensis (C. guianensis) abul is a medicinal plant whose leaves are effectively used for the synthesis of neodymium oxide (Nd2O3) NPs. The 1-butyl 3-methyl imidazolium tetrafluoroborate (BMIM BF4) ionic liquid is used as a stabilizing agent to get better the morphology and biological properties of Nd2O3 NPs. 1-Butene, 4,4-diethoxy-2-methyl is the main compound in C. guianensis abul leaves extract was confirmed by GCMS analysis. The structure of synthesized Nd2O3 (without ionic liquid) and Nd2O3-IL (with ionic liquid) NPs is identified by powder X-ray diffraction (PXRD). The vibrations of the different functional groups were investigated by Fourier-transform infrared (FTIR) and Raman spectroscopy. In UV–Vis spectra, the optical absorption was identified to be 210 and 221nm of Nd2O3 and Nd2O3-IL samples and the PL spectrum provides blue and green emission peaks at 386 and 554 nm. The X-ray photoelectron spectroscopy (XPS) and DLS spectra illustrate the electronic configuration and particle size of the synthesized Nd2O3-IL NPs. The morphology, surface nature and lattice spacing were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The purity and weight percentage of the compound presented can be identified by the energy-dispersive X-ray spectroscopy (EDX). The biomedical properties such as antibacterial, antioxidant, antidiabetic, anti-inflammatory and anticancer activities were investigated. Finally, the overall biocompatible studies reveal that the ionic liquid assisted Nd2O3 NPs can be considered as a potential drug for pharmaceutical and biomedical applications.

Biological applications of green synthesized lanthanum oxide nanoparticles via Couroupita guianensis abul leaves extract

In this work, extract from leaves of Couroupita guianensis (C.guianensis) abul was used as a potential reducing agent for the synthesis of lanthanum oxide (La2O3) nanoparticles (NPs). In addition, the morphology and several physicochemical properties of the La2O3 NPs were improved by introducing the ionic liquid of 1-butyl 3-methyl imidazolium tetra fluoroborate (BMIM BF4) as a stabilizing agent. The structure of the La2O3 (without ionic liquid) and IL-La2O3 (with ionic liquid) NPs were analyzed by X-ray diffraction (XRD). The chemical composition of the synthesized NPs was analyzed using the energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) studies. Optical and morphological studies were also performed. The antibacterial, antioxidant, anti-inflammatory, anti-diabetic and anticancer properties of the La2O3 and IL-La2O3 NPs were evaluated.

Enhanced recovery of astaxanthin from recombinant Kluyveromyces marxianus with ultrasonication-assisted alcohol/salt aqueous biphasic system

Microbial astaxanthin with strong antioxidant activity is greatly demanded for diverse applications. Extractive disruption in aqueous biphasic system (ABS) integrates the cells disruption and biomolecules recovery processes in one-step operation, allowing the direct recovery of intracellular biomolecules with biphasic system upon released from cells. In this study, astaxanthin was recovered from recombinant Kluyveromyces marxianus yeast cells via extractive disruption using alcohol/salt ABS. Recombinant K.marxianus yeast is engineered to produce high concentration of free form astaxanthin. Highest partition coefficient (K= 90.02 ± 2.25) and yield (Y= 96.80% ± 0.05) of astaxanthin were obtained with ABS composed of 20% (w/w) 1-propanol and 20% (w/w) sodium citrate of pH 5, 0.5% (w/w) yeast cells loading and additional of 1% (w/w) 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim)BF4 to improve the migration of astaxanthin to alcohol-rich top phase. The incorporation of 2.5h of ultrasonication to the biphasic system further enhanced the astaxanthin recovery in ABS. The direct recovery of astaxanthin from recombinant K.marxianus cells was demonstrated with the ultrasonication-assisted alcohol/salt ABS which integrates the extraction and concentration of astaxanthin in a single-step operation.

Incorporation of electric fields to ionic liquids-based aqueous biphasic system for enhanced recovery of extracellular Kytococcus sedentarius TWHKC01 keratinase

BackgroundThe purification of keratinase is essential to enhance the catalytic efficiency of keratinase enzyme for industrial applications. Biphasic system incorporated with electric fields is an effective purification tool for the recovery of biomolecules. Ionic liquids (IL) with good conductivity are ideal phase-forming components for biphasic system which promotes the separation of charged biomolecules via electromigration. MethodsThis study aimed to evaluate the effect of electric fields on enhanced recovery of Kytococcus sedentarius TWHKC01 keratinase using IL-based biphasic system. FindingsKeratinase was recovered with biphasic system incorporated with anode in salt-rich bottom phase and cathode in IL-rich top phase operated at 5 V for 5 min. A total of 95.82% ± 0.17 of keratinase was attained with the biphasic system at pH 9 comprising of 20% (w/w) 1‑butyl‑3-methylimidazolium tetrafluoroborate ((Bmim)BF4) and 25% (w/w) ammonium sulphate loaded with 15% (w/w) K. sedentarius TWHKC01 crude feedstock. The selectivity (S) and purification fold (PFT) of keratinase were increased from 7.25 ± 1.50 to 10.87 ± 0.61 and 5.94 ± 0.22 to 8.22 ± 0.44, respectively with the incorporation of electrodes, demonstrating the efficiency of electric fields in enhancing the purity of recovered keratinase.

Synthesis of Silver Nanocatalysts Using Microwave Irradiation in Ionic Liquid for Reduction of Carbon Dioxide to CO By Solar-Driven Electrochemical

Over the last few decades electrochemical CO2 reduction has attracted attention as a promising technology for greenhouse gas reduction. The Carbon monoxide product from CO2 reduction is of interest as a component of syngas for methanol synthesis. Silver is a reactive electrocatalyst toward carbon dioxide reduction to Carbon monoxide among single metals (Au, Zn etc.). In order to carry out CO2 reduction reaction effectively, it is require to nano-sized electro catalyst for wide active area. However, there is aggregation issue of nano-sized particle in liquid phase reduction method from metal precursor. It can be solved simply using of ionic liquid as a solvent and capping agent to suppress aggregation of nano-particle. In addition, Microwave-assisted fabrication has much potential due to their distinctive characteristics such as rapid heating ability, efficient and uniform internal heating, and relatively short process time.Here we describe its use as a single electrocatalyst made in Microwave method with Ionic liquid for reduction of CO2 to CO. We have simply synthesized Ag nanoparticles with an ultra-fine size (~20nm) by microwave irradiation process using Ag precursors dissolve in Ionic liquid. Silver carbonate (Ag2CO3, purchased from Sigma Aldrich) as a precursor was dissolved in Ionic liquid, Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4-, purchased from C-TRI). The 5mL mixture solutions with a concentration of 10, 20 and 30mM were prepared by stirring under atmosphere at room temperature. Each mixture solution was heated by microwave irradiation system (CEM Co.,Ltd Discover) at the power of 10~30W within just 10min.Characterization of synthesized silver nanoparticles was analyzed by Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) to confirm the morphology, chemical state, and crystal structure of the samples. XRD analysis showed (111), (200), (220), (311), and (222) diffractions of Ag metal with a face-centered cubic structure, confirming that the silver nanoparticles could be synthesized. TEM images showed that the nanoparticles have ultra-fine sized silver, less than 20nm without aggregation. Based on CO2 reduction reaction (CO2RR) response, the elctrocatalystic performance of synthesized silver was evaluated. In order to compare the performance, the same mass of commercial Ag and carbon black were used in three electrode system with 0.5M KHCO3 aqueous solution saturated with CO2. The catalytic potential reduced 0.374eV compared to carbon black.In order to confirm the efficiency of Solar-driven electrochemical carbon dioxide reduction, synthsized silver nano catalyst of 9mg/cm2 was loaded at the cathode(6.25cm2) in electrochemical reactor which is a closed two-component separated by anion exchange membrane (Sustainion® X37-50, Dioxide Materials). The anode was IrOx (purchased from Dioxide materials) sprayed on Carbon paper (9cm2). A Si solar cell of series connection solar panels supplied electric power to electrochemical reactor. We achieved the Faradaic Efficiency of 92% to Carbon monoxide conversion by synthesized silver catalyst. We obtained 8.81% to Power conversion efficiency employing series connected Si photovoltaics for CO2 conversion to CO.

Spectroscopic and Photo-Physical Properties of Near-IR Laser Dye in Novel Benign Green Solvents.

IR-792 as near IR (NIR) laser dye was dissolved with different concentrations in two types of ionic liquids (ILs) of different anion and cation, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIM TFSI) & 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4), as the benign green solvent and in methanol (MeOH) as a standard solvent. The behavior of fluorescence of IR-792 dye was studied. The fluorescence of IR-792 dissolved in the ILs was heavily compared to organic solvent. Some photo-physical parameters of IR-792 were calculated. Mainly, IR-792 had a very low quantum yield of fluorescence with high intersystem crossing rate & fluorescence lifetime in picosecond range. Optical absorption and behavior of fluorescence for the rigorously the purified imidazolium ILs in the neat condition and effect of IR-792 on their fluorescence have been examined. The emission behavior of IR-792 in green solvents was independent upon the wavelength of excitation, while the emission behavior of green solvents dependent upon the wavelength of excitation whether in pure state or with NIR laser dye. At most, the intensity of fluorescence of ILs is dependent upon dye concentration.

Primary purification of intracellular Halomonas salina ectoine using ionic liquids-based aqueous biphasic system

Ectoine is a zwitterionic amino acid derivative that can be naturally sourced from halophilic microorganisms. The increasing demands of ectoine in various industries have urged the researches on the cost-effective approaches on production of ectoine. Ionic liquids-based aqueous biphasic system (ILABS) was applied to recover Halomonas salina ectoine from cells hydrolysate. The 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim)BF4 was used in the ILABS and the recovery efficiency of ILABS to recover ectoine from H.salina cells lysate was evaluated by determining the effects of phase composition; pHs; crude loading and additional neutral salt (NaCl). The hydrophilic ectoine was targeted to partition to the hydrophilic salt-rich phase. A total yield (YB) of 96.32% ± 1.08 of ectoine was obtained with ILABS of phase composition of 20% (w/w) (Bmim)BF4 and 30% (w/w) sulfate salts; system pH of 5.5 when the 20% (w/w) of crude feedstock was applied to the ILABS. There was no significant enhancement on the ectoine recovery efficiency using the ILABS when NaCl was added, therefore the ILABS composition without the additional neutral salt was recommended for the primary purification of ectoine. Partition coefficient (KE) of 30.80 ± 0.42, purity (PE) of 95.82% and enrichment factor (Ef) of 1.92 were recorded with the optimum (Bmim)BF4/sulfate ILABS. These findings have provided an insight on the feasibility of recovery of intracellular biomolecules using the green solvent-based aqueous system in one single-step operation.

Synthesis of silver nanoparticles in green binary solvent for degradation of 2,4-D herbicide: Optimization and kinetic studies

In this study, well-dispersed and diminutive Ag nanoparticles have been successfully synthesized in binary solvent of Orthosiphon stamineus (OS) leaves extract and ionic liquids (ILs) via electrochemical method. ILs namely [BMIM Tf2N], [BMIM BF4] and [EMIM EtSO4] were used as solvent in the synthesis process to produce AgTf2N, AgBF4, and AgEtSO4. The characterization of Ag nanoparticles revealed that the particle size of the silver nanoparticles can be easily altered depending on the size of IL alkyl chain and anion, to produce ultrafine particles ranging from 8 to 25nm. Meanwhile, the photocatalytic activity of AgTf2N nanoparticles effectively degraded the highest amount of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide at 65.61%. The optimized model gave high removal percentage of 2,4-D at 97.80% (pH=3.24; catalyst dosage=0.009g/L; 2,4-D concentration=8.15mgL−1) with validation experiments of 1.28% error. Investigation of kinetic reaction showed the applicability of pseudo-first order kinetic to the process of 2,4-D degradation (R2>0.98) which positively predicted the constant elimination amount of 2,4-D throughout the photocatalytic process. Overall, the studies construed the crucial role of binary solvent in synthesizing and controlling the size of Ag nanoparticles for pollutant degradation.

Green Synthetic Protocol for (E)-1-Aryl-3-(2-morpholinoquinolin- 3-yl)prop-2-en-1-ones and Their Antimicrobial Activity

We report here an easy, efficient and green synthetic protocol for the (E)-1-aryl-3-(2-morpholinoquinolin-3-yl)prop-2-en-1-ones by the Claisen-Schmidt condensation of 2-morpholinoquinoline-3-carbaldehyde and different substituted acetophenones by using 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim)BF4. The compounds were characterized by using 1H NMR, 13C NMR and mass spectral data and screened there in vitro antimicrobial activity against different bacterial and fungal organisms.

Ornamental morphology of ionic liquid functionalized ternary doped N, P, F and N, B, F-reduced graphene oxide and their prevention activities of bacterial biofilm-associated with orthopedic implantation

The multifunctional biological active material design for bone tissue engineering is essential to induce osteoblast cell proliferation and attachment. Adhesion of bacteria on biomaterials to produce biofilms can be major contributors to the pathogenesis of implant material associated infections. This research work focuses on NPF& NBF elemental doping and functionalization of reduced graphene oxide using an imidazolium-based ionic liquid such as BMIM PF6 and BMIM BF4 by hydrothermal method. The resulting tri doped reduced graphene oxide (NPF-rGO and NBF-rGO) composite was further used as a scaffold for bone tissue engineering and anti-biofilm activities. The observation of the effect of NPF-rGO and NBF-rGO on the morphology, adhesion and cell proliferation of HOS cell was investigated. Moreover, the tri doped composite tested its antibiofilm properties against B. subtilis, E. coli, K. pneumoniae, and P. aeruginosa pathogenic bacteria. In-vitro studies clearly show the effectiveness of N, P, B, and F doping promoting the rGO mineralization, biocompatibility, and destruction of bacterial biofilm formation. The result of this study suggests that NPF-rGO and NBF-rGO hybrid material will be a promising scaffold for bone reaeration and implantation with a minimal bacterial infection.

Effect of the BMIM BF4 immobilization on oxidized activated carbon in fuel desulfurization

Environmental consequences of high consumption of fossil fuels containing sulfur compounds have promoted research in technologies for their removal. Catalytic hydrodesulphurization currently used requires high temperature and pressure. Alternative technologies based on ionic liquids pure and anchored to matrices have shown good desulfurization properties. Composites offer advantages of reuse, less time consuming and costs, using lower IL amount. In this work, we obtained a solid composite containing [BMIM][BF4] supported on oxidized active carbon and characterized by FTIR, BET, TGA-DSC, and SEM. We evaluated the extraction capacity of benzothiophene, thiophene, dibenzothiophene, and diphenyl sulphide from a model fuel with both pure [BMIM][BF4] as well as the same IL on oxidized activated carbon. In the extraction process using pure IL were achieved removal percentages of up to 69.8% whereas with the composite it was possible to reduce 80 % of the sulfur content.

Pluronic L121, BMIM BF4 and PEG-400 comparison to identify the best solvent for CO2 sorption

The triblock copolymer L121 [poly(ethylene glycol)5-block-poly(propylene glycol)68-block-poly(ethylene glycol)5], the room temperature ionic liquid BMIM BF4 (1-butyl-3-methylimidazolium tetrafluoroborate) and the polymer PEG-400 (polyethylene glycol-400) have been compared in their liquid state to test their sorption capability of CO2 by exposure to high-pressure gas for 3h in a controlled system. The presence of the gas in the studied systems has been determined at atmospheric pressure in the temperature range 288.15–313.15K by using near-infrared (NIR) spectroscopy. The CO2 sorption in BMIM BF4 and PEG-400 was very small and detectable up to 293.15K, only L121 showed the CO2 typical bands in the NIR region of the spectra up to 313.15K, thus a linear correlation can be obtained by plotting the CO2 absorbance of those bands as a function of temperature. The effect induced by temperature on the swelling degree of L121 copolymer has also been investigated.

Do ionic liquids replace water or nanofluids to enhance heat transfer in micro-channel systems?

This study explores the influence of different fluids in a uniform micro-channel geometry on conjugate heat transfer. Nanofluids used here, are SiO2 and Al2O3 nanoparticles with various concentrations up to 4% in water as a base fluid under laminar flow. Nanofluids are compared to an ionic liquid called Butyl Methyl Imidazolium Tetrafluroborate (BMIM BF4) to examine the influence of heat transfer and fluid flow characteristics. Good agreement was found against previous micro-channel studies, numerical simulations with COMSOL Multiphysics® V5.2a are used at Reynolds number ranging from 50 to1000 with a uniform heat flux of 100 W/cm2 relevent to cooling systems. Advanced fluids might offer significant potential in combatting the challenges of heat transfer in the technological drive toward lower weight/smaller volume electrical and electronic devices. The results show that the lowest thermal resistance is for nanofluids followed by water, then the ionic liquid. Moreover, Al2O3-water offers lower thermal resistance than the SiO2-water for all given nanoparticle concentrations. It is also found that there is no beneficial using ionic liquids in forced convection systems which work below boiling temperature conditions.

Large-Amplitude Fourier-Transformed AC Voltammetric Study of the Capacitive Electrochemical Behavior of the 1-Butyl-3-methylimidazolium Tetrafluoroborate–Polycrystalline Gold Electrode Interface

In this paper, the capacitive electrochemical behavior of the 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim BF4)–polycrystalline gold electrode interface is reported over the potential range from −0.37 to 0.53 V vs Fc/Fc+ (Fc = ferrocene). Experimental results are generated by analysis of data (RC model) obtained from large-amplitude Fourier-transformed alternating current voltammetry (FT-ACV) over the frequency range of 10 Hz to 1 kHz. Results suggest a parabolic, U-shaped capacitance versus potential relationship, in stark contrast to present ionic liquid (IL) electrochemical double-layer (EDL) theory. The potential range analyzed was carefully selected to be free of Faradaic current and displays minimal hysteresis with respect to the potential scan direction. Over the selected potential window spanning 0.9 V, the capacitance versus potential curve at 9 Hz exhibits a U-shape, with a capacitance minimum of 19.9 ± 1.3 μF cm–2 at 0.13 ± 0.04 V, flanked by maximum values of 21.2 ± 1.3 and 20.8 ± 1.4 μ...

Imidazolium based ionic liquids as novel benign media for liquid-dye laser systems

Abstract Room temperature ionic liquids (RTILs) have emerged as nature-friendly media suitable for various applications. In this work, Optical absorption, fluorescence behavior and fluorescence lifetime of three rigorously purified imidazolium ionic liquids, 1-butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl4), 1-Butyl-3-methylimidazolium tetrafluoro-borate (BMIM BF4) are studied in the neat condition and with two types of laser dyes (PM-597, Fluorescein). The absorption spectra for this dyes in all the ionic liquid solvents investigated looked very similar while the PL emission spectra differed markedly depending on the type of ionic liquid. In pure imidazolium ionic liquids, non-negligible absorption in the UV region with a long tail extending into the visible region is the main feature of the absorption. The emission behavior of neat ionic liquids is found to be strongly dependent on the excitation wavelength. That ion association gives rise to the long absorption tail and shifting fluorescence maximum. While the emission behavior of dye dissolved in ionic liquids independent on the excitation wavelength. Finally, we discuss the suitability of the imidazolium ionic liquids in optical studies taking into consideration their absorption and fluorescence behavior.

Charge-Induced Long-Range Order in a Room-Temperature Ionic Liquid.

We report direct evidence for charge-induced long-range (ca. 100 μm) order in the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(+)BF4(-)), supported on a silica surface. We have measured the rotational diffusion dynamics of anionic, cationic, and neutral chromophores as a function of distance from a silica surface. The results reflect the excess charge density gradient induced in the IL by the (negative) charge present on the silica surface. Identical measurements in ethylene glycol reveal spatially invariant reorientation dynamics for all chromophores. Capping the silica support with Me2SiCl2 results in spatially invariant reorientation dynamics in the IL. We understand these data in the context of the IL exhibiting a spatially damped piezoelectric response mediated by IL fluidity and disorder.

Nanoparticle Dynamics in Room Temperature Ionic Liquids

Nanoparticle dynamics in Room Temperature Ionic Liquids (RTILs) is an underexplored field, despite high interest in RTILs in nanoparticle synthesis, the modification of electrodes and as catalysts. The solvent environment of a RTIL provides a high ionic strength medium in which to understand nanoparticle dynamics and the role of the capping agent in electron transfer to the nanoparticle. Oxidation of silver nanoparticles capped with poly(ethylene) glycol in 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim BF4) is reported for the first time (J. Phys. Chem. C, 2015, 119 (32), 18808-18815). The oxidation of the nanoparticles shows a time dependency, suggesting that the nanoparticles assemble at the electrode surface and time allows the polymer coating to undergo an unwrapping process before the silver core is accessible for electron transfer with the electrode (‘polymer-gated’). The addition of chloride, commonly present as an impurity in RTILs, allows 'nano-impacts', where by the nanoparticle travels to the electrode surface via Brownian motion before undergoing electron transfer as it makes contact with the electrode, to be observed novelly in a RTIL. (J. Phys. Chem. C, 2016, 120 (3), pp 1959–1965). The presence of the chloride allows the nanoparticles to undergo oxidation to silver chloride, which does not require rearrangement of the polymer. Finally, the importance of the capping agent, and its control over the mechanism of oxidation, has been established (Chem. Eur. J, 2016, doi:10.1002/chem.201505117). Examining nanoparticles capped with 2000, 6000, and 10,000 MW poly(ethylene) glycol reveals a shift in the mechanism of silver oxidation (from nano-impact to polymer gated).

Role of LiBF4 in Ionic Liquid Membranes for Facilitated CO2 Transport.

The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4)/LiBF4 electrolyte was prepared for highly selective facilitated CO2 transport membranes. When LiBF4 was incorporated into BMIM BF4, synergy effects by free Li+ ion and imidazolium cations is expected to enhance the separation performance for CO2/N2 and CO2/CH4. The free state of BF4- ions in BMIM BF4/LiBF4 solutions was investigated by FT-Raman spectroscopy. For the coordination of LiBF4 with BMIMBF4, thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) was utilized. Electrolyte membranes consisting of BMIM BF4 and LiBF4 showed selectivities of 8.40 and 8.25 for CO2/N2 and CO2/CH4, respectively. Neat BMIM BF4 membrane showed selectivities of 5.0 and 4.8, respectively. Enhanced separation performance was attributed to increased free Li+ and abundant free imidazolium cations.