Physical and electrochemical properties of thioether-functionalized ionic liquids

The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 °C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry. Potential windows of the ionic liquids have been obtained at glassy carbon, platinum, and gold electrodes and found to be the largest at glassy carbon, but are limited by oxidation of the thioether-functionalized cation. The voltammetry of IUPAC reference potential scale systems, ferrocene/ferrocenium, cobaltocenium/cobaltocene, and decamethylferrocene/decamethylferrocenium have been evaluated, with the last being most widely applicable. Nonadditivity of Faradaic current is found in the voltammograms of decamethylferrocene in the presence of ferrocene and cobaltocenium. Diffusion coefficient, viscosity, ionic conductivity, double layer capacitance, and other physical properties have also been measured. The dependence of the diffusion coefficient vs viscosity follows the Stokes−Einstein relationship. The properties of the ionic liquids are compared with the related imidazolium family of ionic liquids.

Thermal and chemical properties of wool powders

Wool powders with different particle sizes were examined in terms of their crystal structures, thermal properties, surface chemical compositions and moisture regains. It was found that the crystallinity of wool powders was increased, and the moisture regains were decreased as the particle sizes of wool powders were reduced. For comparison, the properties of activated charcoal were also investigated. The higher dye uptake of activated charcoal at pH 10. compared to that of wool powder, could be due to its greater surface area and porous structure.

Direct synthesis, growth mechanism, and optical properties of 3D AlN nanostructures with urchin shapes

Aluminum nitride (AƖN) nanostructures have shown novel physical and chemical properties that are essential for technological applications. We report a vapor-solid growth of novel three-dimensional (3D) A1N urchin-like nanostmcture in DC arc plasma via the direct reaction between Al vapor and N₂ gas without any catalyst or template. The as-prepared 3D A1N nanostructures which have urchin-like shapes consist of numerous microdaggers with sharp tips and lengths of up to several micrometers and widths of 0.5-2 µm. A growth mechanism of A1N nanostructures with urchin shapes was suggested and explained in detail. The optical properties of the AƖN nanostructures with urchin shapes were also studied with photoluminescence spectrum, which reveals a broad emission, suggesting potential applications in electronic and optoelectronic nanodevices.

Utilizing polypropylene fibers to improve physical and mechanical properties of concrete

The influence of polypropylene fibers has been studied in different proportioning and fiber aspect ratios to improve physical and mechanical properties of fiber-reinforced concretes. Fibers are used in two different lengths (12 mm and 19 mm) and proportions (0.1% and 0.3%) in concrete mixture design. Hardened concrete properties, such as 7- and 28-day compressive strength, splitting tensile strength, flexural strength, water and air absorption, and restrained shrinkage cracking were evaluated.

No statistically significant effects were observed for polypropylene fibers on the compressive strength of concrete, while toughness indexes, splitting tensile and flexural strength and durability parameters showed an increase in the presence of polypropylene fibers. Increased fiber availability (fiber aspect ratio) in the concrete matrix, in addition to the ability of longer polypropylene fibers to bridge on the micro cracks, are suggested as the reasons for the enhancement in mechanical properties. Finally, crack width in fiber-reinforced concrete is calculated analytically with fiber property variables (fiber type, length, diameter and proportion). Results are compared with experimental values and concluded that with an increase in fiber length and/or decrease in fiber diameter crack width, decrease significantly.

Surface modification and properties analysis of shell powder with sodium stearate surface modifier

In this study, shell powder was modified by sodium stearate surface modifier for improving the compatibility of SP with polymer materials. The surface modifiers influence on the physical and chemical properties of SP were studied by scanning electron microscope(SEM), fourier infrared spectrum(FT-IR), surface contact angle meter, XRD diffraction analysis meter and other modern instruments and analysis method. The results showed that the surface modifier was successfully coupled to the shell powder surface. After surface modifier modification, the interfacial compatibility of the shell powder with polymer materials was effectively improved. The contact angle of shell powder surface increased from 73.5 ° to 110.8 °, along with the dosage of sodium stearate surface modifier was 4.0%. All results suggested that modified shell powder is promising for using as a reinforcement filler in polymer materials. © (2014) Trans Tech Publications, Switzerland.

Processing and mechanical properties of hollow sphere aluminum foams

Hollow sphere metallic foams are a new class of cellular material that possesses the attractive advantages of uniform cell size distribution and regular cell shape. These result in more predictable physical and mechanical properties than those of cellular materials with a random cell size distribution and irregular cell shapes. In the present study, single aluminum hollow spheres with three kinds of sphere wall thickness as 0.1 mm, 0.3 mm and 0.5 mm were processed by a new pressing method. Hollow sphere aluminum foam samples were prepared by bonding together single hollow spheres with simple cubic packing (SC) and body-centered cubic packing (BCC). Compressive tests were carried out to evaluate the deformation behaviors and mechanical properties of the hollow sphere aluminum foams. Effects of the sphere wall thickness and packing style on the mechanical properties were investigated.

Novel halogen-free chelated orthoborate-phosphonium ionic liquids : synthesis and tribophysical properties

We report on the synthesis, characterisation, and physical and tribological properties of halogen-free ionic liquids based on various chelated orthoborate anions with different phosphonium cations, both without halogen atoms in their structure. Important physical properties of the ILs including glass transition temperatures, density, viscosity and ionic conductivity were measured and are reported here. All of these new halogen-free orthoborate ionic liquids (hf-BILs) are hydrophobic and hydrolytically stable liquids at room temperature. As lubricants, these hf-BILs exhibit considerably better antiwear and friction reducing properties under boundary lubrication conditions for steel–aluminium contacts as compared with fully formulated (15W-50 grade) engine oil. Being halogen free these hf-BILs offer a more environmentally benign alternative to ILs being currently developed for lubricant applications.

Phenyl-type and C1 stationary phases for environmentally friendlier chromatography

C1 and phenyl-type stationary phases were assessed in terms of their environmental impact on separations using as test solutes polycyclic aromatic hydrocarbons. Methanol (MeOH) and acetonitrile (ACN) mobile-phase gradients were employed. These stationary phases were examined to determine if different physical and chemical properties possessed by these surfaces decreased the organic solvent consumption, and yet maintained peak capacity. The cumulative energy demand (CED) was used to gauge the environmental impact of the separations. The separation of the polycyclic aromatic hydrocarbon test mixture using current methodologies (i.e. a C18/ACN combination) had a CED of 1.13 MJ-eq, and a peak capacity of 27 peaks (resolving 7 of 12 peak pairs with R_s>1). In comparison, a butyl phenyl stationary phase with a methanol mobile phase had a peak capacity of 26, but with a CED of 0.670 MJ-eq. Monolithic columns containing C18 and C1 phases were also tested. A monolithic C18 column with MeOH had the lowest CED at 0.675 MJ-eq, a peak capacity of 28 peaks and good resolving power (resolving ten peak pairs with R_s>1), suggesting that this is a viable option with respect to reducing environmental impact for these types of analyses.

In-situ and tunable nitrogen-doping of MoS2 nanosheets.

Molybdenum disulfide (MoS2) nanosheets have unique physical and chemical properties, which make it a perfect candidate for next generation electronic and energy storage applications. Herein, we show the successful synthesis of nitrogen-doped MoS2 nanosheets by a simple, effective and large-scale approach. MoS2 nanosheets synthesised by this method show a porous structure formed by curled and overlapped nanosheets with well-defined edges. Analysis of the nanosheets shows that they have an enlarged interlayer distance and high specific surface area. X-ray photoelectron spectroscopy analysis shows the nanosheets have Mo-N bond indicating successful nitrogen doping. The nitrogen content of the product can be modulated by adjusting the ratio of starting materials easily within the range from ca. 5.8 to 7.6 at%.

The effect of triacetin as a fuel additive to waste cooking biodiesel on engine performance and exhaust emissions

This study investigates the effect of oxygenated fuels on engine performance and exhaust emission under a custom cycle using a fully instrumented 6-cylinder turbocharged diesel engine with a common railinjection system. A range of oxygenated fuels based on waste cooking biodiesel with triacetin as an oxygenated additive were studied. The oxygen ratio was used instead of the equivalence ratio, or air to fuelratio, to better explain the phenomena observed during combustion. It was found that the increased oxygen ratio was associated with an increase in the friction mean effective pressure, brake specific fuel consumption, CO, HC and PN. On the other hand, mechanical efficiency, brake thermal efficiency, CO2, NOx and PM decreased with oxygen ratio. Increasing the oxygen content of the fuel was associated with a decrease in indicated power, brake power, indicated mean effective pressure, brake mean effective pressure, friction power, blow-by, CO2, CO (at higher loads), HC, PM and PN. On the other hand, the brakespecific fuel consumption, brake thermal efficiency and NOx increased by using the oxygenated fuels. Also, by increasing the oxygen content, the accumulation mode count median diameter moved toward the smaller particle sizes. In addition to the oxygen content of fuel, the other physical and chemical properties of the fuels were used to interpret the behavior of the engine.

The effect of concentrations and properties of phenanthrene, pyrene, and benzo(a)pyrene on desorption in contaminated soil aged for 1 year

Purpose : The choice and timing of microorganisms added to soils for bioremediation is affected by the dominant bioavailable contaminants in the soil. However, changes to the concentration of bioavailable PAHs in soil are not clear, especially when several PAHs coexist. This study investigated the effects of PAH concentration and chemical properties on desorption in meadow brown soil after a 1-year aging period, which could reflect changes of PAH bioavailability during bioremediation. Materials and methods : Based on the percentage of different molecular weights in a field investigation, high-level contaminated soil (HCS) and low-level contaminated soil (LCS) were prepared by adding phenanthrene (PHE), pyrene (PYR) and benzo(a)pyrene (BaP) to uncontaminated meadow brown soil. The concentrations of HCS and LCS were 250 mg kg−1 (PHE, PYR, and BaP: 100, 100, and 50 mg kg−1) and 50 mg kg−1 (PHE, PYR, and BaP: 20, 20, and 10 mg kg−1) respectively. The soils were aged for 1 year, after which desorption was induced by means of a XAD-2 adsorption technique over a 96-h period. Results and discussion : The range of the rapidly desorbing fraction (F rap) for PHE, PYR, and BaP in HCS and LCS was from 1.9 to 27.8 %. In HCS, desorption of PYR was most difficult, and the rate constant of very slow desorption (K vs) of PYR was 8 orders of magnitude lower than that of BaP, which had similar very slow desorbing fractions (49.8 and 50.5 %, respectively). However, in LCS, desorption of PYR was the easiest; the Kvs of PYR was 8–10 orders of magnitude higher than those of PHE and BaP. In HCS, the time scale for release of 50 % of the PAHs was ranked as BaP > PYR > PHE, while in LCS this was BaP > PHE > PYR. Conclusions : The combined effect of PAH concentrations and properties should be taken into account during desorption. The desorption of PAH did not always decrease with increasing molecular weight, and the desorption of four-ring PAHs might be special. These results are useful for screening biodegrading microbes and determining when they should be added to soils based on the dominant contaminants present during different periods, thus improving the efficiency of soil bioremediation.

Extruded products with Fenugreek (Trigonella foenum-graecium) chickpea and rice: Physical properties, sensory acceptability and glycaemic index

The present study investigated the effects of fenugreek flour (Trigonella foenum-graecum) and debittered fenugreek polysaccharide (FenuLife^®) inclusion on the physical and sensory quality characteristics, and glycaemic index (GI) of chickpea–rice based extruded products. Based on preliminary evaluation with different proportions of chick pea and rice, a blend of 70:30 chickpea and rice was chosen as the control for further studies. The control blend, replaced with fenugreek flour at 2%, 5% and 10%, or fenugreek polysaccharide at 5%, 10%, 15% and 20%, was extruded at the optimum processing conditions as specified in the detailed study. The extruded products were evaluated for their physical (moisture retention, expansion, hardness, water solubility index (WSI) and water absorption index (WAI)), sensory (flavor, texture, color and overall acceptability) characteristics and in vitro GI to evaluate their suitability as extruded snack products.

Due to the distinct bitter taste, inclusion of fenugreek flour was not acceptable at levels more than 2% in extruded chickpea based products. Addition of fenugreek polysaccharide resulted in slight reduction in radial expansion (P < 0.05), while longitudinal expansion increased. WAI increased while WSI decreased compared to the control (P < 0.05). The mean scores of sensory evaluation indicated that all products containing fenugreek polysaccharide up to 15% were within the acceptable range. There were no significant differences (P > 0.05) between products containing 5–15% fenugreek polysaccharide in their color, flavor, texture and overall quality.

Fenugreek, in the form of debittered polysaccharide (FenuLife^®) could be incorporated up to a level of 15% in a chickpea–rice blend to develop snack products of acceptable physical and sensory properties with low GI Index.

Optical and photocatalytic properties of nanocrystalline TiO2 synthesised by solid-state chemical reaction

Nanoparticulate TiO₂ is of interest for a variety of technological applications, including optically transparent UV-filters and photocatalysts for the destruction of chemical waste. The successful use of nanoparticulate TiO₂ in such applications requires an understanding of how the synthesis conditions effect the optical and photocatalytic properties. In this study, we have investigated the effect of heat treatment temperature on the properties of nanoparticulate TiO₂ powders that were synthesised by solid-state chemical reaction of anhydrous TiOSO₄ with Na₂CO₃. It was found that the photocatalytic activity increased with the heat treatment temperature up to a maximum at 600 °C and thereafter declined. In contrast, the optical transparency decreased monotonically with the heat treatment temperature. These results indicate that solid-state chemical reaction can be used to prepare powders of nanoparticulate TiO₂ with properties that are optimised for use as either optically transparent UV-filters or photocatalysts.