Browsing by Subject "Co"

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    Free-standing ZnO-CuO composite nanowire array films and their gas sensing properties
    (IOP Publishing, 2011-07-19) Wang, J. X.; Sun, X. W.; Yang, Y.; Kyaw, A. K. K.; Huang, X. Y.; Yin, J. Z.; Wei, J.; Demir, Hilmi Volkan
    A modified hydrothermal method was developed to synthesize ZnO-CuO composite nanostructures. A free-standing film made of ZnO-CuO nanostructures was assembled on the surface of the hydrothermal solution with a smooth surface on one side and a spherical surface on the other side. The structure, growth mechanism and the optical properties of the composite nanostructures were studied. Structural characterizations indicate that the composite nanostructure mainly consisted of two single-crystal phases of CuO and ZnO. The sensitivity for CO gas detection was significantly improved for the composite CuO-ZnO nanostructure film. This method offers a possible route for the fabrication of free-standing nanostructure films of different functional composite oxides.
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    Sorption studies of Cs+, Ba2+, and Co2+ ions on bentonite using radiotracer, ToF-SIMS, and XRD techniques
    (De Gruyter Oldenbourg, 2001) Shahwan, T.; Erten H. N.
    The sorption behaviour of Cs+, Ba2+, and Co2+ ions on bentonite were investigated using the radiotracer method, Time of Flight-Secondary Ion Mass Spectroscopy (ToF-SIMS), and X-Ray Diffraction (XRD). The sorption of Cs+ and Ba2+ were exothermic while sorption of Co2+ was endothermic. The sorption data were well described by Freundlich and Dubinin-Radushkevich isotherms. According to ToF-SIMS results Na+ and Mg2+ were the primary exchanging ions in bentonite. The XRD spectra showed that no structural changes were associated with the sorption of Cs+ and Co2+, and BaCO3 precipitate was formed upon the sorption of Ba2+ on bentonite.
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    ToF-SIMS depth profiling analysis of the uptake of Ba2+ and Co2+ ions by natural kaolinite clay
    (Academic Press, 2004) Shahwan, T.; Erten, H. N.; Black, L.; Allen, G. C.
    The sorption behavior of Ba2+ and Co2+ ions on a natural clay sample rich in kaolinite was studied using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling at 10-Å steps was performed up to a 70-Å matrix depth of the clay prior to and following sorption. The results showed that Co2+ is sorbed in slightly larger quantities than Ba2+, with significant numbers of ions fixed on the outermost surface of the clay. Depletion of the ions K+, Mg 2+, and Ca2+ from the clay lattice was observed to accompany enrichment with Co2+ and Ba2+ ions. The data obtained using X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) indicated insignificant structural and morphological changes in the lattice of the clay upon sorption of both Ba2+ and Co2+ ions. Analysis using energy dispersive X-ray spectroscopy (EDS) showed that the average atomic percentage (±S.D.) of Ba and Co on kaolinite surface were 0.49±0.11 and 0.61±0.19, respectively, indicating a limited uptake capacity of natural kaolinite for both ions. © 2004 Elsevier Inc. All rights reserved.