6H2O Solution Research Articles

Carbon Nanotubes Cathode of Field Emission Lamp Prepared by Electrophoretic Deposition

Field emission lamp is a kind of green and low energy loss light source. Carbon nanotube cathode of field emission lamp was prepared by electrophoretic deposition. Two types of solute salt were added in electrophoretic solution separately, which were used to prepare two types of carbon nanotubes films on identical aluminum sheets by electrophoretic deposition method. Scanning electron microscopy(SEM) were used to observe the surface morphology of the films. The field emission properties of the films were tested by using a diode structure. The turn-on field of the film deposited with CsNO3 / Ca(NO3)2 4H2O solution was 0.7V/μm. The current density of the film was about 4000mA/cm2 at an electric field of 1.8V/μm. While corresponding data by using Mg(NO3)2 6H2O solution was 0.8V/μm and 3800mA/cm2. It is concluded that the field emission properties of the deposited film cathode by using CsNO3/ Ca(NO3)2 4H2O solution better than that using Mg(NO3)2 6H2O solution.

Effect of the Preparation Method on Co/Al<sub>2</sub>O<sub>3</sub> Catalyst Applied to Ethanol Steam Reforming Reaction Production of Hydrogen

Alumina supported cobalt catalysts were prepared, characterized and applied in ethanol steam reforming for hydrogen production. The support and the supported catalysts were prepared, respectively, by the solvothermal and precipitation, impregnation and deposition-precipitation methods. The cobalt was added by impregnation and deposition-precipitation in the Al2O3 supports using a Co(NO3)2·6H2O solution. The solids were characterized, Temperature-Programmed Re-duction with H2 (RTP-H2), X-Ray Diffraction (DRX), BET Nitrogen Adsorption and Temperature Programmed Oxida-tion (TPO). The results indicated that the preparation method and the treatment conditions of samples were appropriate for obtaining the wanted compounds. Co3O4 phase was verified for all catalysts through analyses of DRX and RTP-H2 results. Catalytic tests were performed by varying the temperature from 450?C to 600?C, with water: ethanol molar ratio of 3:1. The ethanol conversion was superior of 99%, with greater hydrogen yield at 600℃. The lower carbon deposition was observed in catalysts prepared with solvothermal/deposition-precipitation methods at 450℃.

Effect of Na Salt on the Formation of MgO Obtained from Mg(OH)2 by Precipitation Method

The particle size of MgO was examined as a function of the Na content in Mg(OH)2 powders and the calcination temperature. Mg(OH)2 suspension was obtained by dropwise precipitation of Mg(NO3)2·6H2O and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to Mg(OH)2 suspension to change the Na salt concentration in the suspension. Mg(OH)2 slurry was filtered and dried at 60˚C under vacuum, and then its Mg(OH)2 powder was calcined to produce MgO with different amount of Na content at 500~900˚C under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the Mg(OH)2 suspension. The particle size of the MgO depends on the Na content remaining in the Mg(OH)2 powder, which powder was prepared by changing the dilution ratio of the Mg(OH)2 suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of Mg(OH)2 to MgO took place, thereby promoting the crystal growth of MgO.

Quantum confinement effect of CdSe induced by nanoscale solvothermal reaction

We report a novel method, nanoscale solvothermal reaction (NSR), to induce the quantum confinement effect of CdSe on nanostructured TiO(2) by solvothermal route. The time-dependent growth of CdSe is observed in solution at room temperature, which is found to be accomplished instantly by heat-treatment in the presence of solvent at 1 atm. However, no crystal growth occurs upon heat-treatment in the absence of solvent. The nanoscale solvothermal growth of CdSe quantum dot is realized on the nanocrystalline oxide surface, where Cd(NO(3))(2)·4H(2)O and Na(2)SeSO(3) solutions are sequentially spun on nanostructured TiO(2), followed by heat-treatment at temperatures ranging from 100 °C to 250 °C. Size of CdSe increases from 4.4 nm to 5.3 nm, 8.7 nm and 14.8 nm, which results in decrease in optical band gap from 2.19 eV to, 1.95 eV, 1.74 eV and 1.75 eV with increasing the NSR temperature from 100 °C to 150 °C, 200 °C and 250 °C, respectively, which is indicative of the quantum confinement effect. Thermodynamic studies reveal that increase in the size of CdSe is related to increase in enthalpy, for instance, from 3.77 J mg(-1) for 100 °C to 8.66 J mg(-1) for 200 °C. Quantum confinement effect is further confirmed from the CdSe-sensitized solar cell, where onset wavelength in external quantum efficiency spectra is progressively shifted from 600 nm to 800 nm as the NSR temperature increases, which leads to a significant improvement of power conversion efficiency by a factor of more than four. A high photocurrent density of 13.7 mA cm(-2) is obtained based on CdSe quantum dot grown by NSR at 200 °C.

Surface properties of the Ni-silica gel catalyst precursors for the vegetable oil hydrogenation process: N2 sorption and XPS studies

The effect of the type of the silica gel pore structure on the surface properties of the Ni-silica gel catalyst precursors for the vegetable oil hydrogenation process has been examined applying N2 sorption and X-ray photoelectron spectroscopy techniques. The nickel catalyst precursors with identical composition (SiO2/Ni = 1.0) has been synthesized by precipitation of Ni(NO3)2 · 6H2O solution with Na2CO3 solution on the three types of silica gel with different pore structures. It is shown that the usage of the silica gel supports with different texture as source of SiO2 causes different location of Ni-species into the support pores and on the external surface area. The XPS data confirm the formation of surface species with different strength of interaction and different dispersion. These surface characteristics of the precursors will predetermine the formation of the active nickel metallic phase as well as the mass transfer of the reactants and products to and from the catalytic sites.

Effect of the support and the reduction temperature on the formation of metallic nickel phase in Ni/silica gel precursors of vegetable oil hydrogenation catalysts

Ni/SiO2 materials with identical composition (SiO2/Ni = 1.0) have been synthesized by precipitation of Ni(NO3)2 · 6H2O solution with Na2CO3 solution on the silica gel, obtained at three different pH values. The present investigation was undertaken in an endeavor to study the effects of the silica gel support type and the reduction temperature on the formation and dispersion of the metallic nickel phase in the reduced Ni/SiO2 precursors of the vegetable oil hydrogenation catalyst. The physicochemical characterization of the unreduced and reduced precursors has been accomplished appropriately by powder X-ray diffraction, infrared spectroscopy, temperature programmed reduction and H2-chemisorption techniques. It can be stated that the texture peculiarities of the silica gels used as supports influence on the crystalline state and distribution of the deposited Ni-containing phases during the preparation of the precursors, on the reduction temperature of the investigated solids as well as on the bulk size and surface dispersion of the arising metallic nickel particles. It was shown that two types of Ni2+-species are formed during the synthesis procedure, namely basic nickel carbonate-like and Ni-phyllosilicate with different extent of presence, location and strength of interaction. The different location of these species is supposed to result in various strength of Ni-O and Ni-O-Si interaction, thus determining the overall reducibility of the precursors. It was specified that the Ni2+-species are strongly bonded to the surface of the silica gel obtained at neutral pH value and weakly bonded to the surface of those prepared in acidic and alkaline conditions. It was established that the precursor, derivates from the silica gel obtained at alkaline conditions, demonstrates both significant reduction of the Ni2+ ions at 430°C and finely dispersed metallic nickel particles on its surface. High dispersion of the metallic nickel might be the crucial reason for achieving of high activity in the vegetable oil hydrogenation.

Electroless Ni-P plating on Mg-Li alloy by two-step method

Pretreated Mg-Li alloy sheets were pre-plated in a NiCO 3·2Ni(OH) 2·4H 2O solution to form a thin Ni-P alloy film and then plating in a NiSO 4·6H 2O solution was carried out to obtain a protective coating. The surface morphology, structure and corrosion resistance of the coating were studied. The results showed that a flat, bright and compact plating layer, which was integrated into the matrix metal, was obtained. The P content of the Ni-P coating reached 13.56% (mass fraction). The hardness value of the Ni-P coating was about HV 549. The polarization curve showed that the corrosion potential of the Ni-P coating reached −0.249 V (vs SCE). A long passivation region was found on the polarization curve, and this phenomenon indicated that the coating has an excellent anti-corrosion property.

Influence of Synthesis Technics and Additives on Cerium Ion Compound Valence

In the system of Ce(NO3)3·6H2O and urea solution during homogeneous precipitation method, hydrothermal homogeneous precipitation coupling method and homogeneous precipitation method with additive, X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to study and characterize the product structures and morphologies. The outer electron configurations and the energy conservation theory were used to analyze the reasons for stability of products and valence state change of cerium ions. The results showed that synthesis technics and additives had a great effect on the cerium ion compound valence. The products were orthorhombic Ce2O(CO3)2·H2O with Valence Ш and orthorhombic CeO(CO3)2·H2O with valence Ⅵ by using homogeneous precipitation method and hydrothermal homogeneous precipitation coupling method, respectively. If an additive (triethanolamine or triethylamine) was added into the homogeneous precipitation system, the products changed into a mixture of orthorhombic CeO(CO3)2·H2O with Valence Ⅵ and cubic CeO2 with valence Ⅳ. It showed that triethanolamine or triethylamine had strong oxidizing properties and played a catalyst role in the reaction.

Conducting Polymer Functionalized Single-Walled Carbon Nanotubes: Synthesis, Morphological Characteristics and Thermal Stability

Nanocomposites of single-walled carbon nanotubes modified polypyrrole (PPy/SWNTs) were synthesized successfully by in situ oxidative polymerization method in the FeCl3·6H2O solution. The morphological structure, electrical conductivity and thermal stability of the nanocomposites were characterized by TEM, SEM, FTIR and TGA. The PPy/SWNTs were 50-100 nm in diameter of PPy coating uniformly on the surface of the SWNTs. FTIR spectra revealed the presence of covalently interaction between the PPy and the carbon nanotubes. The electrical conductivity of PPy/SWNTs composite and pure PPy were 93 and 8.0×10-3 S/cm, respectively. Meanwhile, the PPy/SWNTs composites possessed higher thermal stability (65.9 wt. % weight loss at 600 °C) compared to pure PPy (81.2 wt. % weight loss at 600°C), the content of SWNTs was 15.3 wt. %.

The experiment research of corrosion behaviour about Ni-based alloys in simulant solution containing H 2S/CO 2

Aimed at the problem of tubing corrosion in environment that containing hydrogen sulfide (H 2S), carbon dioxide (CO 2), and chlorides (Cl −), the corrosion behaviour of two nickel based alloys (UNS 06985 and UNS 08825) in 15 wt%NaCl solution containing H 2S/CO 2 in high temperature and high pressure environment was investigated. The pitting corrosion behaviour of Ni-based alloys was studied in FeCl 3·6H 2O solution by means of polarisation curve and immersion tests. The scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) was applied to analyse the microstructure and corrosion performance of the samples. The results showed that the pitting-resistant of nickel alloy UNS 06985 was superior to UNS 08825. With the rising of experimental temperature, the corrosion increased and some slight pitting attacks appeared on the surface of UNS 08825. The test temperature was the crucial factor that influenced not only the compactness and the growing rate of corrosion product scale, but also the corrosion rate of the alloys. Elemental sulfur is a strong oxidant, the presence of S0 leads to a serious localized corrosion. XRD showed that the corrosion films formed on nickel base alloys consisted of NiS, CrO 3, and the oxides of Ni and Fe. The polarisation curves showed a different corrosion behaviour of two alloys, anodic curve of UNS 06985 has a wider passivation area, and there has higher transpassive potential.

Study on the Process Optimization of Synthesizing Co<sub>3</sub>O<sub>4</sub> Nanoparticles by Homogeneous Precipitation Based on Support Vector Regression

The Co3O4 is the major raw material for fabricating lithium cobalt oxide electrode of lithium ion battery. According to the experimental dataset on grain diameter of Co3O4 nanoparticles synthesized by homogeneous precipitation under four main process parameters including the concentration of Co(NO3)2•6H2O solution, mole ratio of reactants, reaction temperature and reaction time, support vector regression (SVR) combined with particle swarm optimization (PSO) for its parameter optimization, is introduced to establish a model for estimating grain diameter of Co3O4 nanoparticles. The comparison of prediction results strongly support the prediction and generalization abilities of SVR are superior to those of multivariable gradual regression (MGR). Meanwhile, the index of grain diameter of Co3O4 nanoparticles under an independent combination of process parameters predicted by SVR model is more accurate than that by MGR model. The multi-factors analysis results based on SVR model are consistent with that of the literatures. This study suggests that SVR is a theoretical significance and potential practical value in development of smaller grain diameter of Co3O4 nanoparticles via guiding experiment.

The effect of seed layer thickness on alignment and morphology of ZnO nanorods

Thin films of ZnO of 20, 40,160 and 320 nm thickness were deposited on Si (100) substrates by rf-magnetron sputtering and then nanorods were grown on the seed layer at 95 °C for 2 h. The ZnO nanorods were synthesized in C 6H 12N 4 and Zn (NO 3) 2·6H 2O solution by a hydrothermal method and the effect of seed layer thickness on the alignment, diameter, density and growth rate of nanorods was studied. The results revealed that the alignment of nanorods depended on crystallinity, grain size and roughness frequency of the sputtered seed layer, so that, with increase of seed layer thickness, crystallinity improved. In addition the grain size increased and the roughness frequency decreased and hence alignment and diameter of nanorods increased. Finally, we present a model for the effect of seed layer thickness on the alignment and diameter of the nanorods.

Synthesis of Nanocrystalline Hydroxyapatite Nanorods via Hydrothermal Conditions

AbstractThe effect of Ca(NO3)2·4H2O and (NH4)2HPO4 primary solutions as the starting materials in the synthesis of a calcium phosphate phase was examined. Therefore, wet chemical reactions were investigated in solution at different temperatures by hydrothermal conditions aimed at hydroxyapatite (Ca10(PO4)6(OH)2, HAp) synthesis. The powders were investigated by XRD, SEM, FE‐TEM, HRTEM, EDAX, SAED, and FTIR. It is found that the HAp have diameters of 25–50 nm and lengths of 120�30 nm with different morphologies. As a matter of fact, the hydrothermal method guarantees the production of HAp for different applications.

Electrochemical synthesis of nanocrystalline SrNb2O6 powders and characterization of their photocatalytic property

Abstract Nanocrystalline SrNb2O6 powders were successfully prepared by a simple electrochemical method for the first time, and the influences of electrolytic solution ingredients, electrolyte concentration, and applied electric current intensity on electrochemical process and products were systemically studied. It was found that the formation of strontium niobates strongly relied on the basic or acidic condition of electrolytic solution. When Sr(OH)2·8H2O or mixed Sr(OH)2·8H2O with SrCl2·6H2O was used as electrolyte, Sr5Nb4O15 and SrNb2O6 phases could simultaneously form, and the relative ratio of Sr5Nb4O15 phase to SrNb2O6 declined with the increase of SrCl2·6H2O content in electrolytic solution. The higher the basicity of electrolytic solution, the more favored the crystallization and development of Sr5Nb4O15 phase. Only monoclinic phase SrNb2O6 was obtained in neutral SrCl2·6H2O solution or acidic solution of SrCl2·6H2O with adding hydrochloric acid solution, and a lower concentration of SrCl2·6H2O (≤0.50 M) was beneficial to the formation of SrNb2O6 phase and stable anodic sparks could be observed. Moreover, the crystallization and development of the nanocrystalline SrNb2O6 powders seem to be not sensitive to the applied electric current intensity, their similar particle size and morphology ultimately result in the resemblance in UV–vis absorption and photodegradation. They show a slight red shift of light absorption onset and better photocatalytic performance compared with that prepared by the solid-state reaction.

Magnesium-Molybate Compounds as Matrix for 99Mo/99mTc Generators

This work reports the preparation of a 99mTc generator based on conversion of 99Mo produced by neutron irradiation, into insoluble magnesium 99Mo-molybdates compounds as matrix. The effect of magnesium salt types and concentration, Mg:Mo molar ratios, pH of molybdate solutions, eluate volume as well as the addition order of molybdate and magnesium solutions' influences on the final 99mTc were evaluated. Polymetalates and polymolybdates salts either crystallized or amorphous were obtained depending on the magnesium salt and Mg:Mo molar ratio used in matrix preparation. 99Mo/99mTc generator production based on magnesium-99Mo molybdate compounds allow reduction of preparation time and eliminates the use of specialized installations. The best generator performances were attained using matrices prepared from 0.1 mol/L MgCl2·6H2O solutions, ammonium molybdate solutions at pH 7 and at a Mg:Mo molar ratio of 1:1.

Realizing NiO nanocrystals from a simple chemical method

Nanocrystalline NiO has been prepared successfully by a simple chemical route using NiCl2·6H2O and NaOH aqueous solution at a temperature of 70°C. The prepared material has been characterized from XRD, SEM, and M–H characteristics. It has been found that NiO nanocrystals have been formed which shows a superparamagnetic/superantiferromagnetic behaviour.

Pressure dependence of structural relaxation time in LiCl + 6H 2O solutions: A preliminary study

In this manuscript we report on the first results of a study performed on LiCl + 6H 2O solutions by inelastic ultraviolet scattering spectroscopy. We estimated the pressure dependence of the structural relaxation time at three different temperatures (297, 255 and 207 K). The comparison of these results with the ones obtained in water could open up the way for further investigations aimed to ascertain the physical origin of water anomalies.

Preparation and measurement of the half-life of 101Tc

101Tc is a very important nuclide as fuel burn up monitor, and its half-life value has been measured many times, however, they were so different from each other. In this work, 101Tc liquid samples were prepared by irradiating analytical pure (NH4)6Mo7O24·4H2O solution in Miniature Neutron Source Reactor (MNSR) of China. A rapid procedure which takes only 5 min was developed to separate 101Tc samples. The final samples were analyzed by γ-ray spectrum using high purity Germanium (HPGe) multi-channel analysis system. The results showed that there were no peaks of other nuclides except 101Tc. The half-life of 101Tc was accurately measured with HPGe γ-detector following 306.8 keV γ-ray for about 140 min, and three methods R-value method, iterative method and translation method were adopted to process the data. Finally, a more precise and accurate value 14.02 ± 0.01 min was given and compared with former measured data.

Unique properties of polyaniline in the presence of applied magnetic field and ferric chloride

Fe-contained polyaniline (abbreviated as PANI–Fe) was prepared by chemical oxidation of aniline with ammonium peroxydisulfate oxidant in 0.5 mol dm −3 HCl and an adequate content of FeCl 3·6H 2O solution in the presence of an applied magnetic field at room temperature. The X-ray photoelectron spectroscopy (XPS) and UV–vis and FTIR spectra suggest that there is an interaction between FeCl 3 and PANI chains, but PANI–Fe backbone is essentially identical with that of parent polyaniline. The electron paramagnetic resonance (EPR) spectrum shows that there were unpaired electrons in PANI–Fe synthesized in the presence of an applied magnetic field, the spin density and the conductivity of which are 7.308 × 10 20 spins g −1 and 0.891 S cm −1, respectively. The plot of magnetization ( M) vs. the applied magnetic field ( H) displays that the PANI–Fe possesses soft ferromagnetic behavior at room temperature. The results of cyclic voltammogram show that the PANI–Fe film is of excellent electrochemical activity.

Removal and adsorption of diuron through nanofiltration membrane: The effects of ionic environment and operating pressures

A study was conducted on the removal and adsorption of diuron through a 200 Da nanofiltration (NF) membrane. The effects of ionic environment (0.002, 0.02 and 0.2 M of NaCl, CaCl 2·2H 2O and MgCl 2·6H 2O solutions), and operating pressure (5 and 25 bar), on the removal and adsorption of diuron, were investigated. There was a gradual increase in the removal efficiency with an increase in ionic strength. However, a better removal performance of NF membrane was achieved with the presence of intermediate ionic strength (0.02 M of NaCl). The presence of the highest ionic strength did not exhibit the highest removal efficiency for diuron. Moreover, ionic strength had a much more significant influence on the removal of diuron at a lower operating pressure (5 bar). The adsorption results indicated that there was a shielding effect of ionic strength on the adsorption of diuron, which was stronger at 5 bar. In contrast, the removal of diuron decreased significantly as the concentration of divalent cations increased at 25 bar. The experimental results also showed that the size exclusion mechanism seemed to be significant with the presence of electrolyte for the removal of diuron through the NF membrane.