Hydrophobicity Of Ionic Liquids Research Articles

Synthesis of Surface-Active Heteropolyacid-Based Ionic Liquids and Their Catalytic Performance for Desulfurization of Fuel Oils.

Surface-active heteropolyacid-based ionic liquids with varying alkyl carbon chains were synthesized, which were subsequently analyzed. The desulfurization of fuels was investigated utilizing various surface-active heteropolyacid-based ionic liquids, and acetonitrile was used as the extractant for the coupling of ODS and EDS. The influences of the alkyl group, surface activity, and hydrophobicity of ionic liquids on sulfur removal were studied. The results suggested that the ionic liquids were stable. Among these ionic liquids, [C4ImBS]3[PW12O40] exhibited the best catalytic performance. Using [C4ImBS]3[PW12O40] as the catalyst, the influences of the catalyst amount, aqueous hydrogen peroxide amount, and reaction temperature on the sulfur removal were explored. Under the optimum conditions, the sulfur removal could achieve 100% efficiency. The recycle experiments also proved that the ionic liquid could be reused.

Extraction of phenolic pollutants from industrial wastewater using a bulk ionic liquid membrane technique

ABSTRACT The academia and chemical industry are actively searching for alternative solvents to meet technology requirements since the most widely used solvents are harmful and volatile. For ionic liquids, there are several advantages over conventionally using organic membrane solvents, including high thermal stability, negligible vapour pressure, low volatility, etc. Here in this study, we have analyzed the abilities of ionic liquids as pure solvents as well as their binary mixtures, to recover phenolic compounds from the industrial wastewater. The field of phenol extraction from wastewater using ionic liquids remains less exposed, and we presume that the work of this kind would open up more and more opportunities for the scientific community as well as industrial people. Based on all these assumptions, the present work includes experimental data of a work which explains the possibilities of room temperature ionic liquids (RTILs) as potential bulk liquid membranes (BLM) for extracting phenol and other phenolic compounds from the industrial affluents. Four high hydrophobicity ionic liquids namely: 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [Bmim][NTf2], 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim] [PF6] and 1-ethyl-3-methyimidazolium bis(trifluoromethanesulfonyl) imide [Emim][NTf2] were used for investigating the Phenol extraction efficiency and stripping efficiency. To provide a best comprehension of the influence of the phenolic structure as well as the nature of cation on the extraction ability of the ILs, we tried to understand the molecular interactions between the phenolic compounds and the solvents. The influence of hydrophobicity of ionic liquids and different kinds of anions on the extraction of phenol and efficiencies of stripping were investigated. All the experimental investigations performed here indicated that the only cation part of the ionic liquid is not an important aspect directly in this extraction, but the hydrogen bonding and the solute-solvent interactions play a significant role in the phenol removal process from aqueous phase to IL phase. First, the optimal conditions of operating (settling time and stirring) were analyzed for the clarity of the experiments performed. Concentration of NaOH in enhancing the performance of ionic liquids was also inspected here in this study. A binary mixture of ionic liquids (BMILs) membrane was examined for the optimized parameters, and the efficiency of phenol extraction was analyzed with the efficiency obtained for the single ionic liquid (SIL) membranes. The phenol concentration was determined by UV/visible spectrophotometer absorbance measurements. The highest phenol extraction efficiencies of 91% and 98.5%, were achieved by using [Bmim][NTf2] and [Bmim][NTf2+PF6] respectively, and the higher stripping efficiencies came up with 79% and 84% respectively, for [Emim][NTf2] and [Bmim + Emim][NTf2]. The results show that the binary mixture ionic liquid (BMIL) membrane is a better choice than single ionic liquid (SIL) membrane solvents. Hence, [Bmim] [(NTf2+PF6)] is an excellent selection as it provides high phenol stripping and extraction efficiencies with a minimal solvent loss and better stability in transport process.

Apparent molar properties of trioctylmethylammonium based ionic liquids in toluene and dodecane at T = (293.15 to 328.15) K

The structural variance ability of ionic liquids (ILs) provides an opportunity to fine tune the thermophysical properties for given application. For effective extraction of metal ion from water, the applied ILs should be hydrophobic and preferably containing non fluorinated anions. The hydrophobicity of ILs can be further manipulated by the addition of diluents. To understand extraction of metal ion using binary mixtures of ILs + diluent, it is utmost important to explore different types of interactions exist in the binary mixtures using thermophysical properties. For this purpose, we present experimentally measured data of densities, ρ and speeds of sound, u for binary solutions of aprotic ionic liquids (APILs) namely trioctylmethylammonioum bis-(2-ethylhexyl) phosphate [TOMA][DEHP], trioctylmethylammonioum bis-(2-ethylhexyl) diglycolamate [TOMA][DGA], trioctylmethylammonioum bis-(2-ethyhexyl)sulfosuccinate [TOMA][DEHS] in toluene and dodecane (diluents) at T = 293.15 K to 328.15 K. The apparent molar properties like volume Vϕ, isentropic compressibility Ks,ϕ and limiting expansivity Eϕ∞ were calculated and explained in terms of temperature, size of anion, and nature of solvent. The both Vϕ and Ks,ϕ were increased with rise in temperature and replacing toluene with dodecane whereas decreased with increase in concentration of APIL. The Redlich-Mayer type equation was used to correlate apparent molar volume, Vϕ∞ and apparent molar isentropic compressibility, Kϕ∞ at infinite dilution. The influence of interactions (IL-IL or IL-solvent) in studied binary mixtures was elucidated by Sv and Sk parameters. It was observed that ion-solvent interactions are dominating in APILs + toluene than in APILs + dodecane.

Ionic Liquid Composite Electrocatalysts for the Oxygen Reduction Reaction

Recent advancements in electrocatalysts for oxygen reduction reaction (ORR) involve changes in electrochemical composition, nanostructure and support mechanism of catalyst layers. Some of the methods described above show significant potential for improving the catalytic performance. But, degradation of the catalyst, due to dissolution, detachment, agglomeration and carbon corrosion, remains the major challenge in utilizing them in actual fuel cell applications. Apart from the catalyst, catalyst-electrolyte interface plays a major role in cathodic ORR. Therefore, modification of this interface presents an alternative method to enhance ORR performance. Here, we present our work to incorporate protic ionic liquids into the catalyst-electrolyte interface in nanostructured as well as single crystal electrocatalysts. These ionic liquid modified electrocatalysts show improved activity and stability in ORR performance because of oxygen solubility and hydrophobicity of ionic liquids. We will present our understanding of the mechanism of activity and stability enhancement due ionic liquid interlayers as well as their integration into membrane electrode assemblies (MEA).

Solubility-switchable Ionic Liquids: A Control of Hydrophilicity and Hydrophobicity Using a Protective Group

Hydrophilicity and hydrophobicity of ionic liquids are readily controlled by attaching or removing a protective group of a diol unit in their cationic part.

Ionic liquid-based microwave-assisted extraction of verbascoside from Rehmannia root

Rehmannia root is widely used as drug and functional food in East Asia and verbascoside content is the main quality control index of Rehmannia root because of its pharmacological activities; thus a fast, and environmentally-benign extraction method of verbascoside from Rehmannia root is a much-needed project. In this work, an ionic liquid (IL)-based microwave-assisted method for the extraction of verbascoside from Rehmannia root was proposed and the driving forces underlying the extraction processes were also explored. Several ILs with different cations and anions and the parameters of microwave-assisted extraction (MAE), including extraction time, the IL concentration, liquid-solid ratio, and microwave irradiation power, were investigated. Experimental results indicated that hydrogen bonding and hydrophobicity of ILs, π–π stacking between ILs and verbascoside, and steric hindrance effect were the fundamental parameters affecting the extraction efficiency. The IL, 1-benzyl-3-methylimidazolium chloride ([Bemim]Cl) showed the highest extraction ability, thus it was selected as the optimal solvent. Meanwhile the optimized extraction conditions were 30 g g–1 of liquid-solid ratio, 0.3 mol L–1 of [Bemim]Cl, 210 W of microwave irradiation power, and 10 s of extraction time. Under the optimal extraction conditions, the extraction yields of verbascoside from fresh, dried, and processed Rehmannia roots were 0.92, 0.34, and 0.22 mg g–1, respectively. Compared with conventional heating reflux extraction and Soxhlet extraction, the IL-based MAE was an efficient and rapid method (extraction time was only 10 s) with simple sample preparation.

Study on the Structure of the Electrical Double Layer Formed in Ionic Liquids Using Neutron Reflectivity

In recent times, ionic liquids (IL) have been studied as a new solvent because of their unique features, in particular, tunability and designability. The electrochemical window, viscosity, conductivity, and hydrophobicity of ILs can be tuned by altering their molecular structures. One of the applications of ILs is an electrolyte solution for electrochemical devices. In the last two decades, many researchers have investigated the IL/electrode interfaces, where the electrochemical reactions exactly occur. It has been well known that both the electrode surface and the electrical double layer (EDL) structure affect the kinetics of electrochemical reactions. However, the IL/electrode interface, especially, the EDL structure has not been well understood. The EDL formed in ILs is assumed to have different structure from that formed in aqueous electrolytes due to IL's high ionic strength. In this study, the EDL structure formed in the deuterated 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM-d15]TFSA) was elucidated using neutron reflectivity (NR) technique. To analyze the EDL structure, it is important that the technique must not the disturb the EDL structure during measurements and the measurement should be carried out under the ideal electrochemical condition. The NR technique satisfies the both conditions. Further, neutron does not decompose organic compounds, including ILs. Therefore, the NR is suitable for the analysis of EDL structure. [BMIM-d15]TFSA was synthesized at the National Deuteration Facility (NDF), Australian Nuclear Science and Technology Organization (ANSTO). Before use, [BMIM-d15]TFSA was dehydrated at 80°C under vacuum for 24 h. Si(100) electrode was used as the working electrode. The working electrode was cleaned with acetone, ethanol, and Milli-Q. Pt wires were used as the reference and counter electrodes. The electrode potential was controlled by IviumStat. The specially designed electrochemical cell for NR measurements made from Kel-F was used and it was assembled in a glove box filled with Ar gas. NR measurements were carried out at BL-17 SHARAKU, Materials and Life Science Experimental Facility (MLF), Japan Proton Accelerator Research Complex (J-PARC). NR profiles were analyzed using Motofit. Firstly, an impedance measurement was carried out to elucidate the flat band potential of Si electrode in [BMIM]TFSA. The flat band potential was estimated at –0.88 V vs Pt. In NR measurements, NR profiles were taken at open circuit voltage (OCV), –1.1 V (negative than the flat band potential) and +0.5 V (positive than the flat band potential). The analysis reveal that at any electrode potential, where we measured in this study, the EDL consists of IL molecule layers and a bulk IL layer. At the electrode potential, E = –1.1 V, [BMIM]+ molecules adsorb on the electrode surface and a TFSA– molecules adsorb on the [BMIM]+ layer. On the other hand, at E = +0.5 V, the stacking order was opposite, i.e., the first and second layer consist of TFSA– and [BMIM]+ molecules, respectively. The electrode surface is negatively charged when the electrode potential is negative than the flat band potential and vice versa. Therefore, these results show that the EDL structure reflects the charge of electrode surface. The detail measurements and analysis are under way.

Distribution Equilibria of Amphoteric 8-Quinolinol between 1-Alkyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide and Aqueous Phases and Their Effect on Ionic Liquid Chelate Extraction Behavior of Iron(III).

The distribution behavior of amphoteric 8-quinolinol (HQ) between ionic liquid (IL) phase and aqueous phase and ionic liquid chelate extraction behavior of iron(III) with HQ were investigated using four 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (CnmimTf2N, n = 2, 4, 6 and 8) ILs. Not only neutral HQ but also cationic H2Q+ were distributed into the IL phase, and the latter distribution based on cation-exchange with Cnmim+ was pronounced in the use of IL having a less-hydrophobic cation, such as C2mim+. In the IL chelate extraction of iron(III), the extractability increased with the increase in the hydrophobicity of IL as the extraction phase. Nevertheless, the determined equilibrium constants for the extraction as the neutral complex FeQ3 were similar to one another. The difference in the extractability among the ILs was due to the difference in the distribution of H2Q+ into the extraction phase. In addition, the cationic coordinatively-unsaturated complex FeQ2+ was also extracted in use of less-hydrophobic C2mimTf2N.

Spectacular Rate Enhancement of the Diels-Alder Reaction at the Ionic Liquid/n-Hexane Interface.

The use of the ionic liquid/n-hexane interface as a new class of reaction medium for the Diels-Alder reaction gives large rate enhancements of the order of 10(6) to 10(8) times and high stereoselectivity, as compared to homogeneous media. The rate enhancement is attributed to the H-bonding abilities and polarities of the ionic liquids, whereas the hydrophobicity of ionic liquids was considered to be the factor in controlling stereoselectivity.

Study on the Behavior of Halide Ions Contained in Ionic Liquids on Au(111) Electrode Surface

In recent times, ionic liquids (IL) have been studied as alternatives to water and organic solvents because of their unique features, in particular, tunability and designability. The electrochemical window, viscosity, conductivity, and hydrophobicity of ILs can be tuned by altering their molecular structures. One of the applications of ILs is as an electrolyte solution for electrochemical devices. In the last decade, many researchers have investigated the electrochemical characteristics of ILs and the behavior of IL/electrode interfaces. On the other hand, the effect of impurity contained in ILs on electrode surface structure has not been well uncovered. Typical impurities are halide ions, alkaline metal ions, and water. It has been well known that the halide ions are adsorbed on metal electrode surface and affect electrochemical processes. Especially, chemically adsorbed halide ions are called “specific adsorption anions”. To understand the effect and the behavior of halide ions exist at electrode/ILs interfaces is important from both scientific and industrial point of views. In this study, the behavior of halide ions on the Au(111) electrode surface in two ionic liquids (IL), 1-buthyl-1-methylpyrrolidiniun bis(trifluoromethylsulfonyl)amide ([BMP]TFSA) and 1-buthyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM]TFSA), was investigated by monitoring the electrode surface structure. Potential dependences of the X-ray diffraction intensity, which originate from the Au(111)-(1 × 1) structure and the surface normal structure, were simultaneously measured with cyclic voltammograms. We considered the dependence of ion concentration and ion species. The electrolytes were prepared using [BMP]Cl, [BMP]Br, [BMP]I, [BMIM]Br, [BMP]TFSA, and [BMIM]TFSA. The electrolytes were dehydrated at 80 °C under vacuum for 24 h before use. A “drop cell” was used as the electrochemical cell. A working electrode was a Au(111) single crystal disk (Φ ≈ 5 mm). Surface X-ray scattering (SXS) experiments were conducted at BL14B1, SPring-8 using a κ-type diffractometer. A 30 keV X-ray was used to obtain a sufficient attenuation length in the drop cell arrangement. In [BMP]TFSA, cyclic voltammograms (CV) showed both halide ion species and their concentration dependence. In the ion species dependence, current values increased in the order of Cl-, Br-, and I-. The cathodic current peak position also shifted to negative potential in the same order. Further, the kinetics of surface reconstruction became faster as the concentration increased. On the other hand, the potential dependence of the surface (1 × 1) structure showed no common behavior. In [BMIM]TFSA, small dependence was observed in both CVs and surface structure. The results revealed that halide ions are co-adsorbed with ionic liquid molecules on electrode surfaces and they increase the mobility of surface atoms. In contrast, the Au(111) surface does not reconstruct to the (p × √3) structure even in the IL containing 200 mM Br−, suggesting that the interaction between halide ions and surface Au atoms is weaker than that between IL molecules and surface Au atoms, that is, the surface property is mainly governed by adsorbed IL molecules. Furthermore, compared with results measured in the two ILs, it was revealed that the effect of halide ions on the Au(111) electrode surface structure depends on the strength of the interaction between IL molecules and surface Au atoms.

Evaluation of the toxicity of ionic liquids on trypsin: A mechanism study

The toxicity of ionic liquids (ILs) was evaluated by using trypsin as biomarker. Experimental results indicated that the trypsin activity was inhibited by ILs and the degree of inhibition highly depended on the chemical structures of ILs. Primary analysis illustrated that hydrophobicity of ILs was one of the driven forces ruling the ILs-trypsin interaction. Thermodynamic parameters, Gibbs free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were obtained by analyzing the fluorescence behavior of trypsin in the presence of ILs. Both negative ΔH and ΔS suggested hydrogen bonding was the major driven force underlying the IL-trypsin interaction. To assess the toxicity of ILs, it should be considered the combination of the hydrogen bonding ability and hydrophobicity of ILs. A regression based model was established to correlate the relationship of the inhibitory ability, hydrophobicity and hydrogen bonding ability of ILs.

New hydrophobic ionic liquids with perfluoroalkyl phosphate and cyanofluoroborate anions

Novel hydrophobic ionic liquids (ILs) with tris(perfluoroalkyl)trifluorophosphate anions (e.g. [(C2F5)3PF3]−; FAP anion), the bis[bis(pentafluoroethyl)phosphinyl]imide (FPI) anion, the tetracyanoborate (TCB) anion, the tricyanofluoroborate (MFB) anion and the dicyanodifluoroborate (DDB) anion have been developed. The properties of these ionic liquids, i.e. their thermal and electrochemical stabilities as well as their viscosities, densities and refractive indices were studied and will be discussed. FAP ionic liquids are more hydrolytically stable and less viscous compared to ionic liquids with the hexafluorophosphate ([PF6]−) anion. The hydrophobicity of ionic liquids with the cyano- and fluoroborate anions [BFx(CN)4−x]− (x = 0–4) strongly decrease in the order: EMIM[B(CN)4] > EMIM[BF(CN)3] > EMIM[BF2(CN)2] > EMIM[BF3(CN)] ∼ EMIM[BF4]; EMIM[BF3(CN)] as well as EMIM[BF4] are miscible with water. The lowest viscosity for all ionic liquids composed of the EMIM cation and weakly coordinating anions as the ones presented herein was observed for EMIM[BF2(CN)2] (11.1 mPa·s at 20 °C).

Swelling and Stability of Polyelectrolyte Multilayers in Ionic Liquid Solutions

Swelling of polyelectrolyte multilayers with aqueous solution of ionic liquid (IL) is examined with a dissipative quartz crystal microbalance. Multilayers are prepared with different combinations of polyelectrolyte, employing PEI(PSS/PAH)4PSS and PEI(PSS/PDADMAC)4PSS. An enhancement of mass coverage and dissipation is found for films in contact with aqueous solution of IL, i.e., 1-hexyl-3-methylimidazolium chloride and 1-methyl-3-methylimidazolium chloride, suggesting incorporation of IL, accompanied by film swelling. Swelling increases with increasing IL concentration. It is strictly reversible up to a stability limit of IL concentration, above which irreversible layer decomposition starts. Each swelling step can be divided into a fast and a slow process, resulting from IL uptake and chain reorganization or layer decomposition, respectively. While absolute IL uptake and swelling limits differ, the concentration dependence is similar in all systems investigated. The swelling is attributed to hydrophobic interactions, since we find a correlation of the swelling with hydrophobicity of IL.

Thermodynamic Studies of Ionic Hydration and Interactions for Amino Acid Ionic Liquids in Aqueous Solutions at 298.15 K

Amino acid ionic liquids are a special class of ionic liquids due to their unique acid-base behavior, biological significance, and applications in different fields such as templates in synthetic chemistry, stabilizers for biological macromolecules, etc. The physicochemical properties of these ionic liquids can easily be altered by making the different combinations of amino acids as anion along with possible cation modification which makes amino acid ionic liquids more suitable to understand the different kinds of molecular and ionic interactions with sufficient depth so that they can provide fruitful information for a molecular level understanding of more complicated biological processes. In this context, volumetric and osmotic coefficient measurements for aqueous solutions containing 1-ethyl-3-methylimidazolium ([Emim]) based amino acid ionic liquids of glycine, alanine, valine, leucine, and isoleucine are reported at 298.15 K. From experimental osmotic coefficient data, mean molal activity coefficients of ionic liquids were estimated and analyzed using the Debye-Hückel and Pitzer models. The hydration numbers of ionic liquids in aqueous solutions were obtained using activity data. Pitzer ion interaction parameters are estimated and compared with other electrolytes reported in the literature. The nonelectrolyte contribution to the aqueous solutions containing ionic liquids was studied by calculating the osmotic second virial coefficient through an application of the McMillan-Mayer theory of solution. It has been found that the second osmotic virial coefficient which includes volume effects correlates linearly with the Pitzer ion interaction parameter estimated independently from osmotic data as well as the hydrophobicity of ionic liquids. The enthalpy-entropy compensation effect, explained using the Starikov-Nordén model of enthalpy-entropy compensation, and partial molar entropy analysis for aqueous [Emim][Gly] solutions are made by using experimental Gibb's free energy data and literature enthalpy data. This study highlights that the hydrophobic interaction persists even in the limit of infinite dilution where the hydration effects are usually dominant, implying importance of hydrophobic hydration. Analysis of the results further shows that the hydration of amino acid ionic liquids occurs through the cooperative H-bond formation with the kosmotropic effect in contrast to the usual inorganic salts or hydrophobic salts like tetraalkylammonium halides.

Nano-silica sorbents immobilized hydrophobic ionic liquids for enhanced adsorptive extraction of cadmium from acidic aqueous solutions

Abstract A method is described for adsorptive removal of cadmium from acidic solutions (pH 1.0) via implementation of nano-silica particles physically impregnated hydrophobic ionic liquids (ILs). Two hydrophobic ILs, [Emim+Tf2N−] and [Omim+Tf2N−], were used to modify the surface of nano-silica amine sorbent [Nano-Si-NH2] for the formation of [Nano-Si-NH2-Emim+Tf2N−] and [Nano-Si-NH2-Omim+Tf2N−], respectively. The highest cadmium adsorption capacity values (1.100–1.200 mmol g−1) were identified in acidic solutions with pH 1.0, while the lowest mmol g−1 values (0.200–0.350) were characterized in solutions with pH 6.0–7.0. Adsorption of cadmium was monitored and optimized under the influence of several operational controlling conditions and factors such as reaction pH, reaction time, sorbent dose, initial cadmium concentration, interfering ions, and hydrophobicity of ILs. [Nano-Si-NH2-Omim+Tf2N−] sorbent was characterized by higher capacity values compared to [Nano-Si-NH2-Emim+Tf2N−] sorbent and this behavior was correlated to the more incorporated hydrophobic character in [Omim+Tf2N−] than [Emim+Tf2N−]. The two modified nano-silica sorbents were successfully implemented for removal of cadmium from acidic (pH 1.0) drinking tap and industrial wastewater with percentage extraction values of 97.78–99.00 ± 2.65. The determined percentage extraction values (93.44–96.87 ± 2.84) were also identified from water samples adjusted to pH 7.0 after three stages of elution in microcolumn approach.

Extraction of zinc(II) from ammoniacal solution into hydrophobic ionic liquids

AbstractBACKGROUND: Separation and recovery of zinc from ammoniacal solutions with solvent extraction is very important in the hydrometallurgical industry. Ionic liquids (ILs) have considerable potential for the separation of metal ions. The extraction behaviour of zinc from ammoniacal solution into three hydrophobic ILs was investigated using β‐diketone as the extractant.RESULTS: The extraction efficiency of zinc for three ILs reached a maximum at pH 7.5 and subsequently decreased with increase of pH and it also decreases with increase of the total ammonia concentration. The overall extraction process is exothermic. The extractability decreases in the IL order: [BMIM]NTf2 > [OMIM]PF6 > [OMIM]NTf2. The results of X‐ray absorption spectra indicate that the coordination number of the extracted zinc complexes decreases with increase in the hydrophobicity of the ILs. The results of five recycling experiments indicate that the three hydrophobic ILs are more stable than [BMIM]PF6 for the extraction of zinc in ammoniacal solutions.CONCLUSION: Hydrophobic ILs combined with β‐diketone can be used to extract zinc from ammoniacal solutions. The extraction of zinc is dependent on the zinc species in ammoniacal solutions and the hydrophobicity of ILs. Moreover, the latter affects both the extractability of extraction systems and the structure of the extracted complexes. © 2012 Society of Chemical Industry

Probing the DNA–ionic liquid interaction using an ultrafast molecular rotor

The interaction of imidazolium based ionic liquids with calf thymus DNA has been investigated using a benzothiazole based ultrafast molecular rotor, Thioflavin-T, as a local reporter. It has been found that the addition of ionic liquid causes large reduction in the emission yield of the DNA bound probe indicating a strong interaction between the ionic liquids and DNA. Detailed studies show that the interaction between ionic liquids and DNA is sufficiently strong to remove the bound probe from the DNA. The excited state lifetime of the DNA bound probe measured by femtosecond fluorescence upconversion technique also corroborate with the above proposition. To understand the nature of the interaction between ionic liquids and DNA, photophysical properties of Thioflavin-T in DNA was investigated in the presence of imidazolium based ionic liquids having alkyl side chain of different lengths in the cationic moiety and the results indicate that apart from electrostatic interaction, the hydrophobicity of ionic liquid also plays a significant role in the ionic liquid–DNA interaction.

Removal of Thiophenic Sulfurs Using an Extractive Oxidative Desulfurization Process with Three New Phosphotungstate Catalysts

Three Keggin-type phosphotungstates, i.e. [C5H5NH]3PW12O40, [C4H6N2H]3PW12O40·3C4H6N2 and [(C4H9)4N]3PW12O40, were synthesized and characterized by elemental analysis, X-ray diffraction, and infrared spectra, meanwhile their catalysis in an extractive catalytic oxidative desulfurization process was studied with ionic liquid (IL) as extractant and H2O2 as oxidant. The main factors affecting the desulfurization process were investigated, including temperature, hydrophobicity of IL, and variety of S-compounds, as well as the amount of catalyst, IL, and H2O2. Under the optimal conditions, the S-content of DBT oil can be decreased from 1000 to 2 ppm. A new interpretation is proposed for the current process, in which IL is assumed as a reaction phase, and the amount of the extracted S-compound and the peroxidized catalyst wherein greatly affect the desulfurization rate. Besides, the IL with the dissolved catalyst can be reused many times and regenerated easily.

Enhanced Adsorptive Removal of Cadmium from Water by Immobilized Hydrophobic Ionic Liquids on Nano-Silica Sorbents

AbstractExcellent adsorptive removal of cadmium was accomplished from a pH 1.0 adjusted acidic aqueous solution by using two physically loaded ionic liquids with various hydrophobicity, [Emim+Tf2N−] and [Omim+Tf2N−], on nano-silica sorbents, [Nano-Si-OH-Emim+Tf2N−] and [Nano-Si-OH-Omim+Tf2N−], respectively. Adjusted solutions to a pH 1.0 were found to produce the highest cadmium adsorption capacity values (1.200–1.300 mmol g−1). An anion exchange mechanism was proposed for such high adsorption of cadmium via the exchange of anionic cadmium species by [Tf2N−] anion. Several operational controlling factors were monitored and optimized, including the reaction pH, reaction time, sorbent dose, initial cadmium concentration, interfering ions, and hydrophobicity of ionic liquids. The more hydrophobic ionic liquid, [Omim+Tf2N−], was found to enhance the adsorption efficiency of the modified sorbent in all evaluated controlling factors. Adsorption equilibrium modeling data were fitted to Brauner-Emmet-Teller and ...

Study of toxicity of imidazolium ionic liquids to watercress (Lepidium sativum L.)

The sensitivity of Lepidium sativum L. germination to three imidazolium ionic liquids was investigated in solutions and soils artificially contaminated with mixtures of those compounds. In case of aquatic solutions, the toxic character of analyzed compounds is connected with their hydrophobicity. The seedling growth is increasing with the decrease in ionic liquid hydrophobicity. The novelty of those studies is the application of high-performance liquid chromatography, which was used for the determination of ionic liquid quantity absorbed by cress. There was almost linear relationship between decrease in root germination and amount of ionic liquid uptaken by cress. Furthermore, the systematic studies on the influence of total organic carbon content in soil on the toxicity of ionic liquids to cress were performed for the first time. Hazardous effects appeared to be closely connected with organic matter: with the decrease of total organic carbon quantity, the inhibition of plant growth was more significant. Visual effects of ionic liquid toxic activity to garden cress are similar as in the case of nutrient deficit in plants.