scholarly journals Adsorption and Impregnation of Alumina with Molybdenum or Tungsten Solutions

1996 ◽  
Vol 13 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Luis R. Pizzio ◽  
Patricia G. Vázquez ◽  
Carmen V. Cáceres ◽  
Mirta N. Blanco
Keyword(s):  
Aqueous Solutions ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Sphere Surface ◽  
Pore Filling ◽  
Tetrahedral Symmetry ◽  
All Solutions ◽  
Sphere Radius ◽  
Tungsten Concentration

The equilibrium parameters of molybdenum and tungsten adsorption on alumina were compared. Adsorptions were performed from aqueous solutions of monomeric or polymeric ions of these elements. For all solutions tested, molybdenum showed a greater affinity for alumina than tungsten. Assuming a pore-filling impregnation of alumina spheres, a model that interprets this process was used for the calculation of theoretical profiles which showed a smooth decrease in concentration along the sphere radius. In turn, the experimental profiles were similar to those predicted for impregnations with solutions of heptameric molybdate, monomeric molybdate and monomeric tungstate. For polymeric tungstate, however, the experimental tungsten concentration rapidly fell to zero near the sphere surface. Using diffuse reflectance spectroscopy, it was observed that the molybdenum was in tetrahedral and octahedral coordination in spheres impregnated with polymeric or monomeric molybdenum solutions; in addition, the ratio of the concentrations of these species was approximately the same. The species observed in spheres impregnated with tungsten solutions was monomeric tungstate, indicating a distortion in tetrahedral symmetry as a consequence of interaction with the alumina.

Photocatalytic Decolorization of Methylene Blue by Ferric Stearate, Ferrocene and NiDBC under Sunlight Irradiation

2011 ◽  
Vol 695 ◽  
pp. 133-136
Author(s):  
Zhao Zhao ◽  
Xue Gang Luo ◽  
Xiao Yan Lin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Methylene Blue ◽  
Aqueous Solutions ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Sunlight Irradiation ◽  
Photocatalytic Decolorization ◽  
Scanning Electron

In this work, ferric stearate, ferrocene and nickel N,N-dibuty dithiocarbamate (NiDBC) were utilized as photocatalyst for the decolorization of methylene blue (MB) aqueous solutions under sunlight irradiation. Pure MB solution was used as reference. Absorption intensities and surface morphology of these photocatalyst were investigated by Diffuse Reflectance Spectroscopy (DRS) and Scanning Electron Microscopy (SEM).The study indicated that ferric stearate had minimal promotion to the decolorization of MB aqueous solutions; and ferrocene exhibited better photocatalysis ability after had been irradiated 60 hours. In this study, NiDBC showed the best photocatalysis ability from the beginning. Furthermore, NiDBC enhanced the decolorization of MB after been irradiated for 31 hours. And after being irradiated 270 hours, the MB aqueous was completely decolorized by NiDBC.

DIFFUSE REFLECTANCE SPECTROSCOPY MONTE-CARLO MODELING: ELONGATED ARTERIAL TISSUES OPTICAL PROPERTIES

2006 ◽  
Vol 39 (18) ◽  
pp. 41-46
Author(s):  
Emilie Péry ◽  
Walter C.P.M. Blondel ◽  
Cédric Thomas ◽  
Jacques Didelon ◽  
François Guillemin
Keyword(s):  
Monte Carlo ◽  
Optical Properties ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Monte Carlo Modeling

Visible-Light-Induced Photocatalytic Activity of Boron-Doped BiVO4

2014 ◽  
Vol 809-810 ◽  
pp. 890-894
Author(s):  
Dan Li ◽  
Lian Wei Shan ◽  
Gui Lin Wang ◽  
Li Min Dong ◽  
Wei Li ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Reflectance Spectroscopy ◽  
Scheelite Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Boron Doped

Boron-BiVO4 samples were synthesized by sol-gel method. They were characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction. Photocatalytic activity of the obtained BiVO4 samples was investigated through degrading methylene blue (MB). The results reveal that boron-BiVO4 catalysts have monoclinic scheelite structure. The BiVO4 and Co-BiVO4 photocatalysts were responsive to visible light. Co-BiVO4 photocatalyst showed higher photocatalytic activity than pure BiVO4, resulting in the significantly improved efficiency of degradation of MB.

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