Electrodeposition of Ni–Fe alloy from a choline chloride-containing ionic liquid

Journal of Solid State Electrochemistry - The electrochemical deposition of a nickel–iron alloy from a plating solution based on a deep eutectic solvent (a eutectic mixture of ethylene glycol...     

Structural-dynamic properties of infinitely dilute ionic liquid–nonpolar compound systems

The effect of nonpolar solvents (argon, methane, and benzene) on the structural-dynamic properties of an ionic liquid (IL), dimethylimidazolium chloride, is studied at 400 K by the method of molecular dynamics using DL_POLY _4.05 software package. The energy and structural-dynamic parameters of infinitely dilute liquid ternary systems are calculated and analyzed. The pattern of motion of the molecules of dilute compound in the IL is described. It is demonstrated that increased size of a solvent molecule enhances the effect on the ionic liquid structure, which also influences the solubility of nonpolar compounds and IL.     

Dispersive liquid–liquid microextraction based on ionic liquid in combination with high-performance liquid chromatography for the determination of bisphenol A in water

A method termed dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography-variable wavelength detection (HPLC-VWD) was developed. DLLME-HPLC-VWD is a method for determination of bisphenol A (BPA) in water samples. In this microextraction method, several parameters such as extraction solvent volume, sample volume, disperser solvent, ionic strength, pH, and disperser volume were optimised with the aid of interactive orthogonal array and a mixed level experiment design. First, an orthogonal array design was used to screen the significant variables for the optimisation. Second, the significant factors were optimised by using a mixed level experiment. Under the optimised extraction conditions (extraction solvent: ionic liquid [C₆MIM][PF₆], 60 µL; dispersive solvent: methanol, 0.4 mL; and pH = 4.0), the performance of the established method was evaluated. The response linearity of the method was observed in a range of 0.002–1.0 mg L^?1 (three orders of magnitude) with correlation coefficient (R ²) of 0.9999. The repeatability of this method was 4.2–5.3% for three different BPA levels and the enrichment factors were above 180. The extraction recovery was about 50% for the three different concentrations with 3.4–6.4% of RSD. Limit of detection of the method was 0.40 µg L^?1 at a signal-to-noise ratio of 3. In addition, the relative recovery of sample of Songhua River, tap water and barrel-drain water at different spiked concentration levels was ranged 95.8–103.0%, 92.6–98.6% and 87.2–95.3%, respectively. Compared with other extraction technologies, there have been the following advantages of quick, easy operation, and time-saving for the present method.     

Nanostructuring of 1-butyl-4-methylpyridinium chloride in ionic liquid–iron oxide nanofluids

Journal of Thermal Analysis and Calorimetry - Understanding the behavior of ionic liquids (ILs) in ionic liquid-based nanofluids has great significance for its proper application. The phase changes...     

An inorganic nano-sorbent based on nickel–aluminum–zirconium ternary-layered double hydroxide for solid-phase extraction of chloride ions

A well crystalline nickel?Caluminum?Czirconium ternary-layered double hydroxide was firstly synthesized and applied as a solid-phase extraction sorbent for the separation of trace levels of chloride ions from aqueous solutions. An indirect method was used for monitoring of the extracted chloride ions. For this purpose, the extracted chloride ions were passed through a reaction column containing silver chloranilate powder and the analyte was precipitated as silver chloride. The concentration of chloranilate ions released from the reaction column, which corresponds to the chloride ions concentration, was then determined spectrophotometrically at 530?nm. The effect of several parameters, such as pH, sample loading flow rate, elution conditions, amount of nano-sorbent, sample volume and effect of potential interfering ions on the recovery was investigated. In the optimum experimental conditions, the limit of detection (3?s) and enrichment factor were 0.12 and 40???g?mL^?1, respectively. The calibration graph using the pre-concentration system was linear in the range of 0.25?C3.00???g?mL^?1 with a correlation coefficient of 0.997. The validation of the presented method was checked by the analysis of two certified reference materials. The optimized method was successfully applied to the determination of chloride ions in waters, food and biological samples.     

A dispersive liquid–liquid microextraction based on a task-specific ionic liquid for enrichment of trace quantity of cadmium in water and food samples

In this work, a hydrophilic task-specific ionic liquid (TSIL) of 1-chloroethyl-3-methylimidazolium chloride functionalized with 8-hydroxyquinoline was used in a dispersive liquid–liquid microextraction method followed by flame atomic absorption spectrometry for the enrichment and determination of trace amounts of cadmium (Cd²⁺) ions. The simultaneous chelation and extraction of Cd²⁺ ions was carried out by the TSIL. Fine droplets of the water-immiscible TSIL containing target analyte were generated in situ by addition of an anion exchanger potassium hexafluorophosphate (KPF₆) salt to the sample tube. After phase separation by centrifugation for 4 min, the sedimented TSIL was diluted with acidified ethanol for measurement of Cd²⁺ content. Some significant parameters influence the preconcentration of Cd²⁺ ions such as sample pH, TSIL volume, amount of KPF₆, non-ionic surfactant and salt concentration were investigated. Under the optimal conditions, calibration curve was linear in the range of 5–250 µg L^?1 Cd²⁺ with correlation coefficient of 0.9975 and a detection limit of 0.55 µg L^?1. The relative standard deviation for six replicate measurements of 50 µg L^?1 Cd²⁺ was 1.5%. The method was successfully applied for the extraction and determination of Cd²⁺ ions in water and food samples.     

Study of the surface properties and surface concentration of ionic liquid–alcohol mixtures

Surface properties for three binary mixtures containing a 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and a long-chain alcohol (1-butanol, 1-pentanol and 1-hexanol) were determined by surface tension data at the following temperatures: (298.15, 308.15, 318.15, 328.15 and 338.15) K. The surface tension data over the entire mole fraction range are correlated by the Fu et al.(FLW) and Myers-Scott (MS) models. There is good agreement between the experimental data and the results of correlations for 15 binary systems (the three systems at five temperatures) with an average relative error below 1.5%. In addition, the UNIFAC group contribution method is applied for calculation of activity coefficients of components in solution. Moreover, the relative adsorptions of alcohol at the air/liquid interface are determined using Gibbs adsorption isotherm. The obtained results show that the values of adsorption for mixtures of alcohols/[BMIM][SCN] increase with increasing the alkyl chain length of alcohol and decreasing temperature.     

Study on chemical constituents and fingerprints of Phellodendron amurense Rupr. based on ultra-performance liquid chromatography–quadrupole–time-of-flight–mass spectrometry

The chemical constituents from Phellodendron amurense Rupr. were characterized systematically by ultra-performance liquid chromatography—quadrupole–time-of-flight–mass spectrometry method for collecting mass spectrometry data, and the fingerprints method was established, providing reference for its quality control. The chromatographic column was ACQUITY UPLC BEH-C₁₈ (100 mm×2.1 mm, 1.7 μm). The mobile phase was acetonitrile-0.1% formic acid aqueous solution and the compounds from P. amurense Rupr. were identified by Qualitative Analysis 10.0 software, reference substance, retention time, mass spectrometry fragmentation pattern and database retrieval. Meanwhile, liquid chromatography–mass spectrometry fingerprint methods of P. amurense Rupr. and Phellodendron chinense Schneid. were established by using the similarity evaluation system of chromatographic fingerprint of traditional Chinese medicine (2012 edition), and the differences were analyzed by multivariate statistical analysis methods. A total of 105 compounds were identified, including 102 alkaloids, two phenolic acids, and one lactone compound. Liquid chromatography–mass spectrometry fingerprint method was established with ideal precision, stability and repeatability, and 12 quality differential markers were recognized between the above two herbs. Liquid chromatography–mass spectrometry method can be used for qualitative analysis of the constituents of Phellodendron amurense Rupr., providing reference for clarifying the material basis and promoting the clinical precision medication and quality evaluation of P. amurense Rupr.     

Pesticide extraction from table grapes and plums using ionic liquid based dispersive liquid–liquid microextraction

Room temperature ionic liquids (RTILs) have been used as extraction solvents in dispersive liquid–liquid microextraction (DLLME) for the determination of eight multi-class pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox, and fenazaquin) in table grapes and plums. The developed method involves the combination of DLLME and high-performance liquid chromatography with diode array detection. Samples were first homogenized and extracted with acetonitrile. After evaporation and reconstitution of the extract in water containing sodium chloride, a quick DLLME procedure that used the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]) and methanol was developed. The RTIL dissolved in a very small volume of acetonitrile was directed injected in the chromatographic system. The comparison between the calibration curves obtained from standards and from spiked sample extracts (matrix-matched calibration) showed the existence of a strong matrix effect for most of the analyzed pesticides. A recovery study was also developed with five consecutive extractions of the two types of fruits spiked at three concentration levels. Mean recovery values were in the range of 72–100% for table grapes and 66–105% for plum samples (except for thiophanate-methyl and carbofuran, which were 64–75% and 58–66%, respectively). Limits of detection (LODs) were in the range 0.651–5.44 μg/kg for table grapes and 0.902–6.33 μg/kg for plums, representing LODs below the maximum residue limits (MRLs) established by the European Union in these fruits. The potential of the method was demonstrated by analyzing 12 commercial fruit samples (six of each type).     

Synergistic effect of a hypophosphorous acid-based ionic liquid and expandable graphite on the flame-retardant properties of wood–plastic composites

Journal of Thermal Analysis and Calorimetry - A hypophosphorous acid-based ionic liquid [Bmim]H2PO2 (BMP) was synthesized and characterized by FTIR, 1HNMR, 13CNMR and 31PNMR. Moreover, a new...     

Development of an ionic liquid based dispersive liquid–liquid microextraction method for the analysis of polycyclic aromatic hydrocarbons in water samples

A simple, rapid and efficient method, ionic liquid based dispersive liquid–liquid microextraction (IL-DLLME), has been developed for the first time for the determination of 18 polycyclic aromatic hydrocarbons (PAHs) in water samples. The chemical affinity between the ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate) and the analytes permits the extraction of the PAHs from the sample matrix also allowing their preconcentration. Thus, this technique combines extraction and concentration of the analytes into one step and avoids using toxic chlorinated solvents. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, type and volume of disperser solvent, extraction time, dispersion stage, centrifuging time and ionic strength, were optimised. Analysis of extracts was performed by high performance liquid chromatography (HPLC) coupled with fluorescence detection (Flu). The optimised method exhibited a good precision level with relative standard deviation values between 1.2% and 5.7%. Quantification limits obtained for all of these considered compounds (between 0.1 and 7 ng L⁻¹) were well below the limits recommended in the EU. The extraction yields for the different compounds obtained by IL-DLLME, ranged from 90.3% to 103.8%. Furthermore, high enrichment factors (301–346) were also achieved. The extraction efficiency of the optimised method is compared with that achieved by liquid–liquid extraction. Finally, the proposed method was successfully applied to the analysis of PAHs in real water samples (tap, bottled, fountain, well, river, rainwater, treated and raw wastewater).     

New innovations in ionic liquid–based miniaturised amperometric gas sensors

Gas detection is an essential part of everyday life; for some applications, using sensors for toxic and hazardous gases can literally mean the difference between life and death. In this minireview, recent progress in amperometric gas sensing using miniaturised electrodes and devices is described. The focus is on the use of nonvolatile room-temperature ionic liquids (RTILs) as electrolytes, which possess inherent advantages such as wide electrochemical windows, high thermal and chemical stability, intrinsic conductivity and good solvating properties. Various different gases, electrodes and RTILs have been investigated in the strive towards new materials for improved gas sensors. The most recent developments using porous membrane electrodes, planar devices (e.g. screen-printed, thin-film, microarray and interdigitated electrodes) and the modification of these surfaces for improved sensitivity are described. RTILs have great potential to be used as electrolytes in amperometric gas sensors, with improved lifespan of the sensor in hot/dry environments and allowing miniaturisation of devices. However, it is clear that more understanding of their long-term operation and utility in real environments (e.g. background air, varying temperatures and humidity levels) is needed before their realisation in successful commercial devices.     

Influence of temperature on thermodynamic properties of acid–base liquid mixtures

Ultrasonic velocity, u density, ?? and viscosity, ?? of mixtures of N,N-dimethyl acetamide with equimolar mixture of ethanol?+?isopropyl alcohol/isobutyl alcohol/isoamyl alcohol, including those of pure liquids over the entire composition have been measured at T?=?308.15, 313.15, and 318.15?K. Using this data, various thermo-acoustic parameters such as deviations in ultrasonic velocity, ?u, isentropic compressibility, ?k _s , viscosity, ????, excess molar volume, $ V_{\text{m}}^{\text{E}} $ and excess Gibb??s free energy of activation for viscous flow, ??G ^*E have been calculated at different temperatures. The calculated deviation and excess functions have been fitted to the Redlich?CKister type polynomial equation. The influence of temperature on the observed negative and positive values of deviation and excess thermodynamic properties has been explained in terms of molecular interactions present in the investigated acid?Cbase liquid mixtures. The experimental data of ultrasonic velocity have been used to check the applicability of velocity models of Nomoto, Van Dael and Vangeel and Junjie and viscosity data have also been availed to test the applicability of standard viscosity models of Grunberg-Nissan, Hind-Mc Laughlin, and Katti-Chaudhary for all the systems investigated at various temperatures.     

A polymer inclusion membrane based on the ionic liquid trihexyl(tetradecyl)phosphonium chloride and PVC for solid–liquid extraction of Zn(II) from hydrochloric acid solution

Abstract  

Extraction of Zn(II) from aqueous solution using polymer inclusion membranes based on poly(vinyl chloride) containing the phosphonium-based ionic liquid trihexyl(tetradecyl)phosphonium chloride (Cyphos^? IL 101) is described. Zn(II) could efficiently be extracted from 5 M hydrochloric acid solution with membranes containing 30 wt% Cyphos IL 101, whereas back-extraction was successfully achieved with 1 M sulfuric acid. Prepared membranes were evaluated in terms of stability in air as well as in terms of leaching of the ionic liquid from the membranes in aqueous solution.     

Development of deep eutectic solvent–based microwave-assisted extraction combined with temperature controlled ionic liquid–based liquid phase microextraction for extraction of aflatoxins from cheese samples

In this study, for the first time, a deep eutectic solvent-based microwave-assisted extraction was combined with ionic liquid–based temperature controlled liquid phase microextraction for the extraction of several aflatoxins from cheese samples. Briefly, the analytes are extracted from cheese sample (3 g) into a mixture of 1.5 mL choline chloride:ethylene glycol deep eutectic solvent and 3.5 mL deionized water by exposing to microwave irradiations for 60 s at 180 W. The liquid phase was taken and mixed with 55 μL 1-hexyl-3-methylimidazolium hexafluorophosphate. By cooling the solution in the refrigerator centrifuge, a turbid state was obtained and the analytes were extracted into the ionic liquid droplets. The analytes were determined by high-performance liquid chromatography equipped with fluorescence detector. Low limits of detection (9–23 ng kg^–1) and quantification (30–77 ng kg^–1), high extraction recovery (66%–83%), acceptable enrichment factor (40–50), and good precision (relative standard deviations ≤ 5.2%) were obtained using the offered approach. These results reveal the high extraction capability of the method for determination of aflatoxins in the cheese samples. In this method, there was no need for organic solvents and it can be considered as green extraction method.     

Friedel–Crafts alkylation of 4-hydroxycoumarin catalyzed by sulfonic-acid-functionalized pyridinium chloride as a new ionic liquid

A green, simple and efficient synthesis of bis-coumarin derivatives via the condensation of 4-hydroxycoumarin with arylaldehydes using sulfonic-acid-functionalized pyridinium chloride {[Pyridine–SO₃H]Cl} as a new, homogeneous and reusable catalyst and ionic liquid is reported.     

Impact of glycosylation on physico–chemical and biological properties of nitrification inhibitors

The lipophilic 2-mercaptobenzothiazole (MBT), known for its nitrification inhibition properties, was derivatized thanks to direct glycosylation reactions. Similar transformations were also performed starting from 2-mercaptobenzimidazole (MBI), structurally close to MBT. The resulting S-linked mono- or disaccharides derived from d-glucose or l-arabinose, and cellobiose, gentiobiose or lactose, respectively, were subsequently studied as novel nitrification inhibitors without any further formulation or physical processes, except dilution in water. Along with ecotoxicity measurements, inhibition properties of the synthesized water soluble glycoconjugates were studied in a model reactor containing nitrification bacteria. The best results were obtained for the gentiobiosyl derivatives simply dissolved in water.     

Local structure of ionic liquid–monohydric alcohol solutions

The method of molecular dynamics is used to investigate the effect of monohydric alcohols on the formation of the local structure of ionic liquids based on the dimethylimidazolium cation at T = 400 K. The intermolecular interaction energies are analyzed to find that the increase in the length of the alkyl chain in the alcohol molecule reduces the influence of the solute molecule on the formation of the local structure of the dmim⁺/Cl^––solute molecule systems. An analysis of the radial distribution function shows that the change in the structure and physical characteristics of the solute molecule does not affect the interaction between the hydroxyl group proton of the alcohol molecule and the ionic liquid anions, whose interactions form the hydrogen bond H^alcohol…Cl^– with a length of 2.3 Å.     

Alkylsulfate-based ionic liquids in the liquid–liquid extraction of aromatic hydrocarbons

The (liquid + liquid) equilibrium data (LLE) for the extraction of toluene from heptane with different ionic liquids (ILs) based on the alkylsulfate anion (R-SO₄) was determined at T = 313.2 K and atmospheric pressure. The effect of more complex R-SO₄ anions on capacity of extraction and selectivity in the liquid–liquid extraction of toluene from heptane was studied. The ternary systems were formed by {heptane + toluene + 1,3-dimethylimidazolium methylsulfate ([mmim][CH₃SO₄]), 1-ethyl-3-methylimidazolium hydrogensulfate ([emim][HSO₄]), 1-ethyl-3-methylimidazolium methylsulfate ([emim][CH₃SO₄]), or 1-ethyl-3-methylimidazolium ethylsulfate ([emim][C₂H₅SO₄])}. The degree of quality of the experimental LLE data was ascertained by applying the Othmer–Tobias correlation. The phase diagrams for the ternary systems were plotted, and the tie lines correlated with the NRTL model compare satisfactorily with the experimental data.     

Bubble points of hydrogen chloride–water–isopropanol and hydrogen chloride–water–isopropanol–benzene systems and liquid–liquid equilibria of hydrogen chloride–water–benzene and hydrogen chloride–water–isopropanol–benzene systems

Bubble points of the HCl–water–isopropanol and the HCl–water–isopropanol–benzene systems and liquid–liquid equilibria (LLE) of the HCl–water–benzene and the HCl–water– isopropanol–benzene systems were measured at 25–85°C and 30–70°C, respectively. The electrolyte nonrandom two-liquid model proposed by Chen et al. [C.-C. Chen, H.I. Britt, J.F. Boston, L.B. Evans, AIChE J. 28 (1982) 588–596] can satisfactorily correlate bubble points and liquid–liquid equilibria of the present mixed-solvent electrolyte systems over the entire range of temperature and concentrations using only binary adjustable parameters.