Thermal conductivities of ionic liquids over the temperature range from 293 K to 353 K

The thermal conductivities of 11 ionic liquids were determined, over the temperature range from 293 K to 353 K, at atmospheric pressure, using an apparatus based on the transient hot-wire method. For each of the ionic liquids studied, the thermal conductivities were found to be between (0.1 and 0.2) W.m(-1).K-1, with a slight decrease observed on increasing temperature. The uncertainty is estimated to be less than +/- 0.002 W.m(-1).K-1. In all cases, a linear equation was found to give a good fit to the data. The effects of water content and chloride content on the thermal conductivities of some of the ionic liquids were investigated. In each case, the thermal conductivities of the water + ionic liquid and chloride + ionic liquid binary mixtures were found to be less than the weighted average of the pure component thermal conductivities. This effect was adequately modeled using the Jamieson correlation. Chloride contamination at typical postsynthesis levels was found to have no significant effect on the thermal conductivities of the ionic liquid studied.

Oxygen solubility in ionic liquids based on 1-alkyl-3-methylimidazolium cations

This work presents the results of oxygen solubility in ionic liquids based on 1-alkyl-3-methylimidazolium cations. Solubility measurements have been carried out in gasometric apparatus at 22, 50 and 90 degrees C under atmospheric pressure. We report the Henry's constants. In general the occurrence of carbon-fluorine bonds and carbon-hydrogen bonds in ionic liquids (ILs) which can create hydrogen bonds with dissolved oxygen, significantly affects the growth of value of solubility constant K-H. Additionally, the stability of ILs towards molecular oxygen was tested. All ILs used in this study were stable in the presence of oxygen and free-radical initiator.

Physical and electrochemical evaluation of ATO supported IrO2 catalyst for proton exchange membrane water electrolyser

Antimony doped tin oxide (ATO) was studied as a support material for IrO₂ in proton exchange membrane water electrolyser (PEMWE). Adams fusion method was used to prepare the IrO₂-ATO catalysts. The physical and electrochemical characterisation of the catalysts were carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder conductivity, cyclic voltammetry (CV) and membrane electrode assembly (MEA) polarisation. The BET surface area and electronic conductivity of the supported catalysts were found to be predominantly arisen from the IrO₂. Supported catalyst showed higher active surface area than the pristine IrO₂ in CV analysis with 85% H₃PO₄ as electrolyte. The MEA performance using Nafion®−115 membrane at 80 °C and atmospheric pressure showed a better performance for IrO₂ loading ≥60 wt.% than the pristine IrO₂ with a normalised current density of 1625 mA cm⁻² @1.8 V for the 60% IrO₂-ATO compared to 1341 mA cm⁻² for the pristine IrO₂ under the same condition. The higher performance of the supported catalysts was mainly attributed to better dispersion of active IrO₂ on electrochemically inactive ATO support material, forming smaller IrO₂ crystallites. A 40 wt.% reduction in the IrO₂ was achieved by utilising the support material.

On sea level change in the North Sea influenced by the North Atlantic Oscillation: local and remote steric effects

In this study, contributions of both local steric and remote baroclinic effects (i.e., steric variations external to the region of interest) to the inter-annual variability of winter sea level in the North Sea, with respect to the North Atlantic Oscillation (NAO), for the period of 1953–2010 are investigated. On inter-annual time scales in this period, the NAO is significantly correlated to sea level variations in the North Sea only in the winter months (December–March), while its correlation to sea temperature over much of the North Sea is only significant in January and February. The discrepancy in sea level between observations and barotropic tide and surge models forced by tides and local atmospheric forcing, i.e., local atmospheric pressure effects and winds, in the present study are found to be consistent with previous studies. In the North Sea, local thermosteric effects caused by thermal expansion play a minor role on winter-mean NAO related sea level variability compared with atmospheric forcing. This is particularly true in the southeastern North Sea where water depths are mostly less than 25 m. Our calculations demonstrate that the discrepancy can be mostly explained by remote baroclinic effects, which appear as water mass exchanges on the continental shelf and are therefore only apparent in ocean bottom pressure. In the North Sea, NAO related sea level variations seem to be a hybrid of barotropic and baroclinic processes. Hence, they can only be adequately modelled with three-dimensional baroclinic ocean models that include contributions of baroclinic effects and large-scale atmospheric forcing external to the region of interest.

Polarisabilities of alkylimidazolium ionic liquids

The molar polarisability and molar volume for 71 ionic liquids were extracted from 157 measurements of their refractive index and density, which were then further deconstructed into atomic contributions by means of a Designed Regression analysis. Using this approach, the density and refractive index for any chosen ionic liquid with alkyl-substituted imidazolium cations can be predicted in good agreement with experimental data.

CO2 Capture in Wet and Dry Superbase Ionic Liquids

The solubility of carbon dioxide in five tetraalkylphosphonium superbase ionic liquids, namely the trihexyltetradecylphoshonium phenoxide, trihexyltetradecylphoshonium benzotriazolide, trihexyltetradecylphoshonium benzimidazolide, trihexyltetradecylphoshonium 1,2,3-triazolide, and trihexyltetradecylphoshonium 1,2,4-triazolide was studied experimentally under dry and wet conditions at 22 A degrees C and at atmospheric pressure, using a gravimetric saturation technique. The effects of anion structure and of the presence or absence of water in the solution on the carbon dioxide solubility were then deduced from the data. H-1 and C-13-NMR spectroscopy and ab initio calculations were also conducted to probe the interactions in these solutions, as carbon dioxide and water can compete in the ionic liquid structure during the absorption process. Additionally, the viscosity of selected superbase ionic liquids was measured under dry and wet conditions, in the presence or absence of CO2, to evaluate their practical application in carbon dioxide capture processes. Finally, the recyclability of the trihexyltetradecylphoshonium 1,2,4-triazolide under dry and wet conditions was determined to probe the ability of selected solvents to solubilize chemically a high concentration of carbon dioxide and then release it in a low energy demand process.

A facile method for synthesizing PVA/Au, PVA/Ag and PVA/AuAg nanocomposites

In this paper, we presented a facile way of preparing PVA/Au, PVA/Ag and PVA/AuAg nanocomposites through in situ synthesis of metal nanoparticles in PVA hydrogel network using a room temperature atmospheric pressure microplasma. This is the first time microplasma technology is used for the fabrication of hydrogel based nanocomposites. The materials synthesized have been characterized for their microstructure and antibacterial properties. The nanoparticles synthesized within the PVA hydrogel network are found to be better dispersed than those synthesized in water, and their size and shape are more uniform. The new approach has opened a new avenue towards multi-scale synthesis of green and multi-functional nanocomposites, which may find wide range of potential applications in biomedical field.

Increasing Fruit and Vegetable Intake Has No Dose-Response Effect on Conventional Cardiovascular Risk Factors in Overweight Adults at High Risk of Developing Cardiovascular Disease

BACKGROUND: Improving diet and lifestyle is important for prevention of cardiovascular disease (CVD). Observational evidence suggests that increasing fruit and vegetable (FV) consumption may lower CVD risk, largely through modulation of established risk factors, but intervention data are required to fully elucidate the mechanisms by which FVs exert benefits on vascular health.

OBJECTIVE: The aim of this study was to examine the dose-response effect of FV intake on cardiovascular risk factors in adults at high CVD risk.

METHODS: This was a randomized controlled parallel group study involving overweight adults (BMI: >27 and ≤35 kg/m(2)) with a habitually low FV intake (≤160 g/d) and a high total risk of developing CVD (estimated ≥20% over 10 y). After a 4-wk run-in period where FV intake was limited to <2 portions/d (<160 g/d), 92 eligible participants were randomly assigned to 1 of 3 groups: to consume either 2, 4, or 7 portions (equivalent to 160 g, 320 g, or 560 g, respectively) of FVs daily for 12 consecutive weeks. Fasting venous blood samples were collected at baseline (week 4) and post-intervention (week 16) for analysis of lipid fractions and high-sensitivity C-reactive protein (hsCRP) concentrations. Compliance with the FV intervention was determined with use of self-reported FV intake and biomarkers of micronutrient status. Ambulatory blood pressure and body composition were also measured pre- and post-intervention.

RESULTS: A total of 89 participants completed the study and body composition remained stable throughout the intervention period. Despite good compliance with the intervention, no significant difference was found between the FV groups for change in measures of ambulatory blood pressure, plasma lipids, or hsCRP concentrations.

CONCLUSIONS: There was no evidence of a dose-response effect of FV intake on conventional CVD risk factors measured in overweight adults at high CVD risk. This trial was registered at clinicaltrials.gov as NCT00874341.

Evaluation of the ionic liquids 1-alkyl-3-methylimidazolium hexafluorophosphate as a solvent for the extraction of benzene from cyclohexane : ( Liquid + liquid ) equilibria

In the catalytic hydrogenation of benzene to cyclohexane, the separation of unreacted benzene from the product stream is inevitable and essential for an economically viable process. In order to evaluate the separation efficiency of ionic liquids (ILs) as a solvent in this extraction processes, the ternary (liquid + liquid) equilibrium of 1-alkyl-3-methylimidazolium hexafluorophosphate, [Cnmim][PF6] (n = 4, 5, 6), with benzene and cyclohexane was studied at T = 298.15 K and atmospheric pressure. The reliability of the experimentally determined tie-line data was confirmed by applying the Othmer–Tobias equation. The solute distribution coefficient and solvent selectivity for the systems studied were calculated and compared with literature data for other ILs and sulfolane. It turns out that the benzene distribution coefficient increases and solvent selectivity decreases as the length of the cation alkyl chain grows, and the ionic liquids [Cnmim][PF6] proved to be promising solvents for benzene–cyclohexane extractive separation. Finally, an NRTL model was applied to correlate and fit the experimental LLE data for the ternary systems studied.

Deep separation of benzene from cyclohexane by liquid extraction using ionic liquids as the solvent

Separation of benzene and cyclohexane is one of the most important and difficult processes in the petrochemical industry, especially for low benzene concentration. In this work, three ionic liquids (ILs), [Bmim][BF ₄], [Bpy][BF ₄], and [Bmim][SCN], were investigated as the solvent in the extraction of benzene from cyclohexane. The corresponding ternary liquid-liquid equilibria (LLE) were experimentally determined at T = 298.15 K and atmospheric pressure. The LLE data were correlated with the nonrandom two-liquid model, and the parameters were fitted. The separation capabilities of the ILs were evaluated in terms of the benzene distribution coefficient and solvent selectivity. The effect of the IL structure on the separation was explained based on a well-founded physical model, COSMO-RS. Finally, the extraction processes were defined, and the operation parameters were analyzed. It shows that the ILs studied are suitable solvents for the extractive separation of benzene and cyclohexane, and their separation efficiency can be generally ranked as [Bmim][BF ₄] > [Bpy][BF ₄] > [Bmim][SCN]. The extraction process for a feed with 15 mol % benzene was optimized. High product purity (cyclohexane 0.997) and high recovery efficiency (cyclohexane 96.9% and benzene 98.1%) can be reached. © 2012 American Chemical Society.