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Abstract: In this paper, we report on the absorption and photoluminescence properties of Tm3+/Dy3+ ions co-doped oxyfluoride germanate glasses for white light emission. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of the host glass have been carried out to confirm its structure and thermal stability. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been evaluated for Tm3+ and Dy3+ ions. A combination of blue, yellow and red emissions has emerged in these glasses, which allows the observation of bright white light when the glasses are excited by the ultraviolet light. The white light luminescence colour could be changed by varying the excitation wavelength. Also, various colours of luminescence, including white light, can be easily tuned by adjusting the concentrations of Tm3+ or Dy3+ ions in the co-doped glasses. Concentration quenching effect was also investigated and possible energy transfer mechanism from Dy3+→Tm3+ ions was explained which is also confirmed by the decay lifetime measurements. [Copyright &y& Elsevier]

Although China has been regarded as one of the largest anthropogenic mercury emission source with coal combustion, so far the actual measurements of Hg species and Hg emissions from the combustion and the capture of Hg in Chinese emission control devices were very limited. Aiming at Hg mercury species measurements in Guiyang, the capital city of Guizhou province in Southwest China, we studied flue gases of medium-to-small-sized industrial steam coal-firing boiler (10–30t/h) with no control devices, medium-to-small-sized industrial steam coal-firing boiler with WFGD and large-scale coal combustion with ESPs using Ontario Hytro method. We obtained mercury emission factors of the three representative coal combustion and estimated mercury emissions in Guiyang in 2003, as well as the whole province from 1986 to 2002. Coal combustion in Guiyang emitted 1898kg mercury to the atmosphere, of which 36% Hg is released from power plants, 41% from industrial coal combustion, and 23% from domestic users, and 267kg is Hgp>>, 813kg is Hg2+>> and 817kg is Hg0>>. Mercury emission in Guizhou province increased sharply from 5.8t in 1986 to 16.4t in 2002. With the implementation of national economic strategy of China''s Western Development, the annual mercury emission from coal combustion in the province is estimated to be about 32t in 2015. [Copyright &y& Elsevier]

Abstract: In this paper, we report on a novel design strategy of an efficient sorbent for removal of trace contaminants from water. This kind of sorbent is composed of a nonporous core of SiO2 nanofiber and a mesoporous shell (denoted as nSiO2@mSiO2 (“n” means “nonporous” and “m” means “mesoporous”)). The nSiO2@mSiO2 fiber possesses a continuously long fibrous shape and mesoporous micromorphology, thus, showing both high sorption capacity and separability. The flexible nonporous SiO2 nanofiber was prepared with electrospinning first, followed by covering a mesoporous SiO2 shell based on a modified Stöber method using CTAB (cetyltrimethylammonium bromide) as the directing agent for formation of the mesopores. Also, functional thiol groups were grafted on the nSiO2@mSiO2 to enhance its performance. With a large specific surface area and long fibrous morphology, the nSiO2@mSiO2 fiber and its thiol-functionalized counterpart exhibit impressive performance on removal of Pb2+ and Cd2+ from water. Furthermore, the flexible texture and fibrous morphology of the nSiO2@mSiO2 fiber also made the removal of metal ions and the separation process more convenient and efficient, implying that the nSiO2@mSiO2 fiber could have great potential for industrial applications. [Copyright &y& Elsevier]