RESUMEN
The nitrogen and fluorine co-doped TiO2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetrabutyl titanate with ammonium fluoride. Nitrogen and fluorine co-doping causes the absorption edge of TiO2 to shift to a lower energy region. The photocatalytic activity of co-doped TiO2 with anatase phases was found to be 2.4 times higher than that of the commercial TiO2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co-doped TiO2 powders only contain anatase phases even at 1000 degrees C. Apparently, ammonium fluoride added retarded phase transformation of the TiO2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co-doped TiO2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO2 to shift to a lower energy region.
Asunto(s)
Contaminantes Ambientales , Luz , Compuestos Orgánicos/química , Fotoquímica/métodos , Titanio/química , Absorción , Compuestos de Amonio , Catálisis , Fluoruros/química , Flúor/química , Nitrógeno/química , Compuestos de Amonio Cuaternario , Temperatura , Difracción de Rayos XRESUMEN
Aerobic heterotrophic granular sludge was cultivated in a sequencing batch shaking reactor (SBSR) in which a synthetic wastewater containing glucose as carbon source was fed. The characteristics of the aerobic granules were investigated. Compared with the conventional activated sludge flocs, the aerobic granules exhibit excellent physical characteristics in terms of settleability, size, shape, biomass density, and physical strength. Scanning electron micrographs revealed that in mature granules little filamentous bacteria could be found, rod-shaped and coccoid bacteria were the dominant microorganisms.