Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 8 Articles
Various quaternary CuInxGa1-xS2 (0 = x = 1) chalcopyrite nanoparticles have been prepared from molecular single-source\r\nprecursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility.\r\nDepending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This\r\nmethod has been used to generate up to 5 g of nanoparticles and up to 150 g from multiple batch reactions with excellent\r\nreproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown\r\nhigh reproducibility in nanoparticle size, composition, and bandgap....
The leaching of copper using thiosulfate reagent as an alternative reagent to cyanide has been investigated\r\nsince it is almost presented in gold thiosulfate leaching. This paper addressed the investigation of adsorption of\r\ncopper complexes on anion exchange resin in non-ammoniacal and ammoniacal thiosulfate leaching systems.The\r\nwork provided the experimental procedures for the adsorption of copper complexes on strong based anion exchange\r\nresin in non-ammoniacal and ammoniacal resin-solution systems. The result showed that increasing ammonia in the\r\nsolution resulted in the diminishing total copper complexes on the resin. As the solution pH of resin-solution systems\r\nwas maintained by the ammonia solution added in the system, the same effect of ammonia on the total copper\r\ncomplexes on resin was also shown. Overall, non-ammoniacal resin-solution system gave much better adsorption\r\nisotherm of copper complexes on resin, and the dominant species copper complexes on the strong based anion\r\nexchange resin was expected to be Cu(S2O3)3\r\n based on leaching modelling....
In the present work porous poly (vinylidene fluoride) (PVDF) hollow fiber membranes were fabricated via thermally induced phase separation (TIPS) method for the application in gas-liquid membrane contactor. For this purpose long air gap distance was used (90 mm). Scanning electron microscopy (SEM) was used for membrane characterization. Gas permeation test was performed using carbon dioxide as test gas. It was observed that the effective surface porosity and membrane pore size increased with increased glycerol concentration. CO2 absorption using the fabricated hollow fiber membranes were measured in a gas-liquid hollow fiber membrane contactor. The results of the CO2 absorption rate of the tested fibers revealed that complete removal of CO2 was achieved using 7% glycerol added to the casted solution at normal operating conditions for equal gas to liquid volumetric flow rates using sodium hydroxide as absorbent liquid....
In this paper, Nano-sized copper-cobalt compound oxide powders have been prepared by sol-gel technique with\r\ndifferent mole ratios of Cu/Co (from 0.00 to 0.15); Detection of the methane gas, the most chemically stable hydrocar-\r\nbon, is done. The structural properties and morphology of powders were studied by X-ray diffraction (XRD), Fourier\r\ntransform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). XRD analysis confirms that\r\nCo3O4 and (CuO0.3CO0.7) Co2O4 phases have been formed and mean grain size were decreased with increasing dop-\r\nant (from 28 to 24nm). According to TEM images it was found that the particles have cubic morphologies with nearly\r\nuniform distribution. Then an adaptive neuro-fuzzy inference system (ANFIS) models have been utilized for prediction\r\nof sensitivity values of the corresponded sensor. The results of ANFIS model show that the independent predicted\r\nSensitivity values (S) compared to the measured target values have a good agreement. And also, high coefficient\r\nwere found (R2 > 0.98) for the response....
The phase behavior of methyl substituted esters monolayers of n-HFA (n-higher fatty acids) at the air−water interfaces are studied at 200C. The measurement of surface pressure has been invariably done in all these systems, by using modified Wilhelmy,s slide method. The collected π-A data provided isotherms for each of the compounds. The observed shapes of ‘π-A’ curves provided much similarly with some of those are available in the literature. The surface pressure values for various monolayers arising from these methyl substituted esters have been found to lie in the range: 1.86-22.84 dynes/cm, with some small deviation for the individual members. The π-A data presented in tables clearly reveal that the limiting area per molecule values for various esters lie well within the range: 18.91– 45.93 (A02) on air-water interface at 200C. While optimum surface pressure values lie in the range: 9.47-22.84 dynes/cm. The esters of certain long-chain acids are reported to form monolayers involving highly imperfect gaseous phases. Even at low pressures such as 0.2 - 0.4 dynes/cm. these are shown to have molecular areas very much below that for a perfect gas. Further it has been concluded that these films may: either undergo transition to the intermediate phase, which upon reduction of area may change to an L2 phase, and if the pressure of collapse is not too low, into a solid phase, or collapse to provide liquid lenses. The solid phase of the monolayer ultimately collapsed at 20.8 A02 and 19.5 dynes/cm....
Bimetallic Pd-Pt catalyst was successfully prepared via conventional heating (CH), microwave (MW), and\r\nultrasonic irradiation (US) methods. Bimetallic Pd-Pt nanoparticles stabilized with polyvinylpyrrolidone (PVP) were\r\nprepared with molar ratio of PVP to metal, 40:1. Smaller particles sizes with narrow distribution obtained after 30min\r\nand 10min with US and MW methods respectively. All the particles are spherical or near spherical in shape.\r\nThe average particles size and size distribution for Pd-Pt (US) nanoparticles was 1.28 �± 0.29 nm, while for Pd-Pt\r\n(MW) nanoparticles was 1.05 �± 0.21 nm. The average particles sizes of these bimetallic nanoparticles are comparable\r\nwith the classical CH method, which was 1.23 �± 0.25 nm. Based from the XPS analysis, surface compositions of Pd\r\nand Pt show that PdPt(CH) and PdPt(MW) catalyst were enriched with Pd, meanwhile PdPt (US) composition was\r\ncomparable and it might be in alloy structure formation. The activity of these three catalysts for the hydrogenation\r\nreaction of palm olein was studied. The reaction conducted under ambient temperature and atmospheric pressure.\r\nA molar ratio of palm olein to catalyst of 25000:1 has been used in the hydrogenation reaction to determine the\r\nconversion of linoleate, selectivity of trans-isomer and iodine value (IV) in the hydrogenated palm\r\nolein. After 180 min of reaction, full conversion achieved with Pd-Pt (MW) catalyst, while only 91.4% and 80.6%\r\nconversion achieved with Pd-Pt (US) and Pd-Pt (CH) respectively. However, the Pd-Pt (MW) catalyst shows the\r\nhighest elaidate selectivity after 180 min, which was up to 13.1%, meanwhile the elaidate selectivity of 11.82% and\r\n8.1% for both Pd-Pt (US) and Pd-Pt (CH) respectively. Even though higher conversion of linoleate achieved in\r\nshort time and lower trans selectivity produced with Pd-Pt bimetallic catalyst. The IV calculated shows that Pd-Pt\r\n(MW) catalyst has the lowest IV then followed by Pd-Pt (US) and Pd-Pt (CH) catalysts....
The generation of test gas from pure liquids has a wide variety of applications in laboratory and field experiments, for which the\r\nquality of the test gas is of significance. Therefore, various methods for test gas generation have been designed. Each method has\r\nunique advantages and disadvantages. Thus, a short overview is presented within the scope of this paper. Furthermore, a common\r\nbubbler system is presented, which was built to generate test gas from volatile organic compounds for experimental usage in\r\nlaboratory applications. An analysis is conducted with respect to the generated concentrations at different temperatures and flow\r\nrates of the diluting gas. Accuracy and stability of this method are investigated....
Dehydration of sugars to 5-hydroxymethylfurfural (HMF) has recently been under intensive study by a multitude of research\r\ngroups. On the other hand, when lignocellulosic biomass is applied as the starting material, very few studies can be found in the\r\nopen literature. The direct synthesis of HMF, in line with the idea of ââ?¬Å?one-potââ?¬Â synthesis strategy from lignocellulose, is demanding\r\nsince the overall process should encompass dissolution, hydrolysis, and dehydration steps in a single processing unit. Ionic liquidassisted\r\nmethods to produce hydroxymethyl-furfural directly from lignocellulosic biomass are reported here together with a short\r\noverview of the most important biofuels. In reality, HMF is not suitable to be used as a single-component fuel as such, and,\r\nconsequently, methods to produce HMF derivatives suitable as liquid fuels are reported....
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