The Experts below are selected from a list of 10695 Experts worldwide ranked by ideXlab platform
Joaquim L Faria - One of the best experts on this subject based on the ideXlab platform.
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photocatalytic degradation of chromotrope 2r using nanocrystalline tio2 activated carbon composite catalysts
Applied Catalysis B-environmental, 2007Co-Authors: Wendong Wang, Claudia G Silva, Joaquim L FariaAbstract:Composite catalysts made of nanocrystalline TiO2 and carbon were prepared by a modified sol–gel method over activated carbon (AC). The composite catalysts were characterized by N2 adsorption–Desorption Isotherm, TG, diffuse reflectance UV–vis spectroscopy, XRD and SEM. The photocatalytic activity was tested on the degradation of Chromotrope 2R (C2R) in aqueous medium under UV radiation. The composite catalysts exhibited higher activities than commercial Degussa P25 alone and the photocatalytic process was more efficient than the pure photolytic degradation. A modified Langmuir–Hinshelwood approach was used to study the kinetics and to determine the adsorption equilibrium constant and the reaction rate constant. Two different mechanisms are proposed and discussed in order to explain the observed synergy. # 2006 Published by Elsevier B.V.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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photocatalytic degradation of phenol on mwnt and titania composite catalysts prepared by a modified sol gel method
Applied Catalysis B-environmental, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and nanocrystalline titania composite catalysts were prepared by a modified sol–gel method. Thermogravimetric analysis, N 2 adsorption–Desorption Isotherm measurements, powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and UV–vis spectra were carried out to characterize the composite catalysts with different MWNT contents. The results suggest that the presence of MWNT embedding in the composite catalysts matrix prevents TiO 2 particle agglomeration. Additionally, a correlation exists between the MWNT content and the changes in the UV–vis absorption properties. The photocatalytic degradation of phenol was chosen as a model reaction to evaluate the photocatalytic activities of the composite catalysts. An optimum of the synergetic effect was found for a weight ratio MWNT/TiO 2 equal to 20%. The effects induced by MWNT on the composite catalysts may be explained in terms of a strong interphase interaction between MWNT and TiO 2 in the composite catalysts.
Wendong Wang - One of the best experts on this subject based on the ideXlab platform.
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photocatalytic degradation of chromotrope 2r using nanocrystalline tio2 activated carbon composite catalysts
Applied Catalysis B-environmental, 2007Co-Authors: Wendong Wang, Claudia G Silva, Joaquim L FariaAbstract:Composite catalysts made of nanocrystalline TiO2 and carbon were prepared by a modified sol–gel method over activated carbon (AC). The composite catalysts were characterized by N2 adsorption–Desorption Isotherm, TG, diffuse reflectance UV–vis spectroscopy, XRD and SEM. The photocatalytic activity was tested on the degradation of Chromotrope 2R (C2R) in aqueous medium under UV radiation. The composite catalysts exhibited higher activities than commercial Degussa P25 alone and the photocatalytic process was more efficient than the pure photolytic degradation. A modified Langmuir–Hinshelwood approach was used to study the kinetics and to determine the adsorption equilibrium constant and the reaction rate constant. Two different mechanisms are proposed and discussed in order to explain the observed synergy. # 2006 Published by Elsevier B.V.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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photocatalytic degradation of phenol on mwnt and titania composite catalysts prepared by a modified sol gel method
Applied Catalysis B-environmental, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and nanocrystalline titania composite catalysts were prepared by a modified sol–gel method. Thermogravimetric analysis, N 2 adsorption–Desorption Isotherm measurements, powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and UV–vis spectra were carried out to characterize the composite catalysts with different MWNT contents. The results suggest that the presence of MWNT embedding in the composite catalysts matrix prevents TiO 2 particle agglomeration. Additionally, a correlation exists between the MWNT content and the changes in the UV–vis absorption properties. The photocatalytic degradation of phenol was chosen as a model reaction to evaluate the photocatalytic activities of the composite catalysts. An optimum of the synergetic effect was found for a weight ratio MWNT/TiO 2 equal to 20%. The effects induced by MWNT on the composite catalysts may be explained in terms of a strong interphase interaction between MWNT and TiO 2 in the composite catalysts.
P J Mcdonald - One of the best experts on this subject based on the ideXlab platform.
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use of bench top nmr to measure the density composition and Desorption Isotherm of c s h in cement paste
Microporous and Mesoporous Materials, 2013Co-Authors: Aca Muller, Karen Scrivener, A M Gajewicz, P J McdonaldAbstract:H nuclear magnetic resonance (NMR), supported by a measurement of the degree of hydration using X-ray diffraction, has been used to fully characterise the nano-scale porosity and composition of calcium-silicate-hydrate (C-S-H), the active component of cement. The resultant "solid" density and composition are ρ = 2.68 g/cm; (Ca). (Si,Al)O. (HO) for an underwater cured, never-dried cement paste with an initial mix water-to-cement ratio of 0.4 after 28 days of hydration. In addition, the first pore-type resolved Desorption Isotherm of cement that shows the location of water as a function of relative humidity has been measured. Critical to our results is verification of the assignment of the different NMR spin-spin relaxation time components. These have been corroborated with conventional analyses. The new methodology is key to enabling design of cement pastes with lower environmental impact.
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use of bench top nmr to measure the density composition and Desorption Isotherm of c s h in cement paste
Microporous and Mesoporous Materials, 2013Co-Authors: Aca Muller, Karen Scrivener, A M Gajewicz, P J McdonaldAbstract:H-1 nuclear magnetic resonance (NMR), supported by a measurement of the degree of hydration using X-ray diffraction, has been used to fully characterise the nano-scale porosity and composition of calcium-silicate-hydrate (C-S-H), the active component of cement. The resultant "solid" density and composition are rho = 2.68 g/cm(3); (Ca)(1.53)center dot(Si-0.96,Al-0.04)O-3.51 center dot(H2O)(1.92) for an underwater cured, never-dried cement paste with an initial mix water-to-cement ratio of 0.4 after 28 days of hydration. In addition, the first pore-type resolved Desorption Isotherm of cement that shows the location of water as a function of relative humidity has been measured. Critical to our results is verification of the assignment of the different NMR spin-spin relaxation time components. These have been corroborated with conventional analyses. The new methodology is key to enabling design of cement pastes with lower environmental impact. (C) 2013 Elsevier Inc. All rights reserved.
Philippe Serp - One of the best experts on this subject based on the ideXlab platform.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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photocatalytic degradation of phenol on mwnt and titania composite catalysts prepared by a modified sol gel method
Applied Catalysis B-environmental, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and nanocrystalline titania composite catalysts were prepared by a modified sol–gel method. Thermogravimetric analysis, N 2 adsorption–Desorption Isotherm measurements, powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and UV–vis spectra were carried out to characterize the composite catalysts with different MWNT contents. The results suggest that the presence of MWNT embedding in the composite catalysts matrix prevents TiO 2 particle agglomeration. Additionally, a correlation exists between the MWNT content and the changes in the UV–vis absorption properties. The photocatalytic degradation of phenol was chosen as a model reaction to evaluate the photocatalytic activities of the composite catalysts. An optimum of the synergetic effect was found for a weight ratio MWNT/TiO 2 equal to 20%. The effects induced by MWNT on the composite catalysts may be explained in terms of a strong interphase interaction between MWNT and TiO 2 in the composite catalysts.
Philippe Kalck - One of the best experts on this subject based on the ideXlab platform.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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visible light photodegradation of phenol on mwnt tio2 composite catalysts prepared by a modified sol gel method
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-Desorption Isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.
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photocatalytic degradation of phenol on mwnt and titania composite catalysts prepared by a modified sol gel method
Applied Catalysis B-environmental, 2005Co-Authors: Wendong Wang, Philippe Serp, Philippe Kalck, Joaquim L FariaAbstract:Abstract Multi-walled carbon nanotubes (MWNT) and nanocrystalline titania composite catalysts were prepared by a modified sol–gel method. Thermogravimetric analysis, N 2 adsorption–Desorption Isotherm measurements, powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and UV–vis spectra were carried out to characterize the composite catalysts with different MWNT contents. The results suggest that the presence of MWNT embedding in the composite catalysts matrix prevents TiO 2 particle agglomeration. Additionally, a correlation exists between the MWNT content and the changes in the UV–vis absorption properties. The photocatalytic degradation of phenol was chosen as a model reaction to evaluate the photocatalytic activities of the composite catalysts. An optimum of the synergetic effect was found for a weight ratio MWNT/TiO 2 equal to 20%. The effects induced by MWNT on the composite catalysts may be explained in terms of a strong interphase interaction between MWNT and TiO 2 in the composite catalysts.