Advanced Materials Research Vols. 391-392

Abstract: Utilization of solid-phase extraction (SPE) to remove aqueous strontium ions by adsorption onto activated sodium trititanate whisker (STW) was investigated in this work under the conditions of various pH value, STW amount, shaken time and contact time by flame atomic absorption spectrometry (FAAS). The optimum conditions obtained were: pH value = 5.0, STW amount = 0.2 g, shaken time = 5 min and contact time of 3 h on the remove of 2 mg·L^-1 strontium(II). The adsorption of Sr(II) on activated STW follows pseudo-second order kinetics and the maximum adsorption capacity Q being 8.37 mg·g^-1 at 25°C. Finally, the detection limit (3σ) of 0.030 μg·mL^-1 with the relative standard deviation (RSD) for 1.0 μg·mL^-1 Sr(II) of 0.93 % (n=10) were obtained. Results showed that activated STW was a solid-phase extraction sorbent of efficient, low-cost, convenient adsorption of Sr(II) from aqueous solution and could be reused for five times with about 8.0%-9.0% regeneration loss.

Abstract: A series of liquid crystalline (LC) oligomer films (IP-VP) were prepared by use of cyclo(tetramethylhydrogeno)siloxane (CTMHS), and two different cholesteric monomers that possess ortho- or para-substituted benzene. The chemical structures, liquid-crystalline properties and optical properties of the synthesized materials were characterized by various experimental techniques. All the samples showed cholesteric phase with very wide mesophase temperature ranges. From IP to VP, the glass transition temperature and the isotropic temperature decreased slightly with increase of C2PB component in the polymer systems. The maximum reflection bands shift to long wavelength from IP to VP, suggesting the helical pitch become longer with more ortho-substituted benzene in the polymer systems

Abstract: The microstructure of the galvanized coating was investigated using scanning electron microscope equipped with energy dispersive X-ray spectroscope. The immersing and electrochemical corrosion tests were carried out to study the corrosion resistance of the galvanized coating. The addition of Bi in Zn-bath affects remarkably the morphology of the galvanized coating. The thickness of δ + ζ phase layer in the coating reaches the maximum when the content of Bi in Zn-bath is 0.5 wt.%. The corrosion resistance of the galvanized coating declines with the increase of the content of Bi.

Abstract: Basing on the basic preparation principle of reactive powder concrete, through mixing the new active component of slag, this thesis aims to confect new-type cement-based material with super high performance. As illustrated from the experiments of resistance to chlorine ion permeability, this type of concrete is with extremely compact structure and higher resistance to chlorine ion permeability compared with other cement-based materials. Silica fume presents the most important promotion effect on its resistance to chlorine ion permeability. Steel fiber and standard sand also help to enhance its impermeability. Through the analysis and the research on microstructure realized by X-ray Diffraction, mercury penetration experiment and SEM, all these views have been proved.

Abstract: Conducting polyaniline (PANI) nanofibers were synthesized by interfacial polymerization with ethanol/water, n-butyl alcohol/water and n-hexyl alcohol/water as reaction media, respectively. It was characterized by four-probe method, FTIR, UV-Vis, XRD, SEM techniques etc. The results showed that the n-butyl alcohol/water system provided a better reaction environment for the preparation of PANI nanofibers. The optimal conductivity value of PANI nanofibers was 3.55 S/cm; the diameter was between 60 and 100nm and the length was from 600nm to several microns. The electromagnetic shielding effectiveness of the PANI nanofibers was from 38dB to 79dB, which was measured by coaxial method from 10KHz to 4GHz. According to the results, the PANI nanofibers could be used as electromagnetic shielding materials.

Abstract: For the purpose of obtaining the high-efficiency TiO₂ photocatalyst carrier, the mechanism and influences of different substrates on photocatalytic activities of TiO₂ membranes were investigated. Three kinds of membranes TiO₂/Al₂O₃/Al, TiO₂/Al and TiO₂/glass were prepared using the dip-coating method. Methyl orange solution with pH=3 and initial concentration 20 mg/L was degraded under the UV irradiated for 2 h with three membranes. The discoloring ratios are 74.7%, 59.1%, 52.6% respectively after 1h, and become above 96% after 2 h. It indicates that Al and Al₂O₃/Al as carriers are able to enhance photocatalytic activities to some extent, while glass just as carrier that have no influence.

Abstract: Mixed conducting oxides SrFeCo_0.5O_y was synthesized by citrates sol-gel method. The effect of calcining atmosphere on synthesis process of samples was studied. The crystal structure and morphology of calcined powders were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM) and the bulk density of sintered samples was determined by Archimedes method. The experimental results showed that the dominant phase perovskite Sr-Fe-Co-O oxides was prepared by calcining in oxygen. The powder obtained had flake shape and the particle was smaller. The dominant phase orthorhombic Sr-Fe-Co-O oxides was prepared by calcining in argon. The powder obtained had sphere shape and the particle was bigger. The bulk density of samples sintered at low temperature in oxygen was smaller than that of in argon. The reaction mechanism of samples calcined in different atmosphere was also discussed.

Abstract: The isothermal section of the Fe-Zn-Nb ternary system at 600 oC was determined using the equilibrated alloys with the aid of diffusion couple approach. The specimens were investigated by means of SEM-EDS analysis, SEM-WDS analysis and X-ray diffraction. A true ternary phase T was identified, this phase is in equilibrium with ε, NbZn3, Γ, δ, and η - Zn phases respectively in the system. The solubility of Nb in η - Zn and δ phase is limited and that of Zn in ε is up to 10.0%.

Abstract: Supported Co–Mo nitride catalysts have been synthesized by incipient-wetness impregnation method and temperature-programmed reaction in N2-H2 mixed gases. The effect of support types, namely carbon nanotubes(CNTs), active carbon(AC), 5A zeolite and Al2O3 on the properties of the prepared catalysts for ammonia decomposition has been investigated by XRD, H2–TPR and SEM techniques. The results showed that CNTs was the optimum support for Co–Mo nitride catalyst. At 550 , NH3 conversions over CoMoNx/AC, CoMoNx/Al₂O₃ and CoMoNx/5A Zeolite catalysts were only 14.7%, 65.4% and 68.7%, respectively, while NH3 conversion over CoMoNx/CNTs catalyst was up to 84.4%. XRD and H2–TPR results indicated that the active species consist of CoMoO₄, MoO₃, γ-Mo2N and Co3Mo3N crystallites, which can be reduced at elevated temperatures at H2 atmosphere. The SEM characterization demonstrated that Co-Mo nitrides particles disperse uniformly on the CNTs.

Abstract: In order to analyze the antioxidant conversion rate of hydrogen peroxide as oxidant to make oxidation starch, and the change of starch crystallinity when mixing different amount of antioxidant, the determination of carboxyl content and X-ray diffraction analysis map have been analyzed by adding 5ml, 10ml, 15ml, 20ml, 25ml mix amount of oxidation starch respectively to starch and oxidizer. We can get the conclusion that the conversion rate of hydrogen peroxide is 0.062%.We know that crystallinity of 6 different oxidation starches reduced with the increase of oxidant amount. Confirm that the hydrogen peroxide have a weak influence on the crystallinity of starch.