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Photocatalytic Reaction (photocatalytic + reaction)
Selected AbstractsGraphite Oxide as a Photocatalyst for Hydrogen Production from WaterADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Te-Fu Yeh Abstract A graphite oxide (GO) semiconductor photocatalyst with an apparent bandgap of 2.4,4.3,eV is synthesized by a modified Hummers' procedure. The as-synthesized GO photocatalyst has an interlayer spacing of 0.42,nm because of its moderate oxidation level. Under irradiation with UV or visible light, this GO photocatalyst steadily catalyzes H2 generation from a 20,vol % aqueous methanol solution and pure water. As the GO sheets extensively disperse in water, a cocatalyst is not required for H2 generation over the GO photocatalyst. During photocatalytic reaction, the GO loses some oxygen functional groups, leading to bandgap reduction and increased conductivity. This structural variation does not affect the stable H2 generation over the GO. The encouraging results presented in this study demonstrate the potential of graphitic materials as a medium for water splitting under solar illumination. [source] Oxidative polymerization of pyrrole photocatalyzed by TiO2 nanoparticles and interactions in the compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Zhen Weng Abstract Oxidative polymerization of pyrrole is initiated by photoexcited TiO2 nanoparticles. Pyrrole oligomers and polypyrrole (PPy) are continuously produced with reaction time. The conversion of pyrrole monomer changes as a function of the concentration of TiO2 nanoparticles. It is found that PPy in the composite has the conjugated structure and is partially oxidized with a formation of positively charged N+. Results from X-ray photoelectron spectroscopy and Raman analysis consistently indicate that a strong interaction is established between the TiO2 and PPy. According to the results of UV,vis spectroscopy, a mechanism of photocatalytic oxidation is proposed for this polymerization. The interaction between TiO2 and PPy is found to arise from the photocatalytic reaction and discussed in terms of photoinduced Ti3+. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Characterization of a photocatalytic reaction in a continuous-flow recirculation reactor systemJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2006Fumihide Shiraishi Abstract A continuous-flow recirculation mode, generally called a recycle mode, is known to be practically meaningless except when the reactant is separated from the product at the reactor exit or when the reaction is autocatalytic, because when simply circulating a small amount of the fluid containing a reactant, the reactant concentration in this mode is lowered due to mixing of the fluid at the reactor entrance, leading to a decrease in the conversion at the reactor exit. This mode may, however, be meaningful in photocatalytic reactions with very large film-diffusional resistance. To indicate the validity of this estimation, therefore, characteristics of a continuous-flow recirculation reactor have been investigated both theoretically and experimentally. As a result, it is found that by increasing the circulation flow rate the conversion and productivity in this reactor is higher than that in a continuous-flow reactor because the film-diffusional resistance is remarkably reduced. Copyright © 2006 Society of Chemical Industry [source] Enhanced Ability of Nanostructured Titania Film to Assist Photodegradation of Rhodamine B in Water Through Natural AgingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2007Jin-Ming Wu Gradually but significantly improved abilities of titania films with various nanofeatures and crystal structures to assist photodegradation of trace rhodamine B in water were observed when the films were subjected to natural aging. The so-called natural aging behavior can be attributed to the gradual increase in the surface hydroxyl groups that are beneficial to the photocatalytic reaction. [source] Degradation of phenylarsonic acid and its derivatives into arsenate by hydrothermal treatment and photocatalytic reactionAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2005Tsunenori Nakajima Abstract The degradation of phenylarsonic acid (PA) and its derivatives by hydrothermal treatment (HTT) was examined, especially focusing on the effect of adding H2O2 upon the degradation efficiency. The degradation was assessed by the generation of arsenate resulting from the cleavage of AsC bonds in the PA derivatives. When PA (without substituents) was subjected to an HTT with H2O2 (H2O2 -HTT; 0.5,1% H2O2) at 175,200 °C, PA was almost completely degraded into arsenate, whereas an HTT with NaOH (NaOH-HTT; 3 M NaOH) at the temperatures provided almost no degradation. The H2O2 -HTT also worked well for the degradation of PA derivatives with hydroxy and/or nitro groups on the phenyl ring. However, the degradation of aminophenylarsonic acids was not favorably performed by the H2O2 -HTT. The effect of the structure of PA derivatives upon the degradation susceptibility was discussed. A photocatalytic reaction using TiO2 was also attempted for the degradation of PA derivatives. Copyright © 2005 John Wiley & Sons, Ltd. [source] Removal of organic dyes in the hybrid photocatalysis/nanofiltration systemASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Joanna Grzechulska-Damszel Abstract The removal of azo dyes acid red 18 (AR18), direct green 99 (DG99) and acid yellow 36 (AY36) in hybrid photocatalysis/nanofiltration (NF) system was investigated. The photocatalytic reactions were conducted in the flow reactor with immobilized photocatalyst bed. A commercially available titanium dioxide (Aeroxide® P25, Degussa, Germany) was used as a photocatalyst. The solution after the photocatalytic reaction was applied as feed for NF process. The changes of various parameters, including concentration of dyes, pH and conductivity of the solution, total organic carbon (TOC) and total dissolved solids (TDS) content were analyzed during the process. It was found that azo dyes AR18, DG99 and AY36 solutions could be successfully decolorized in the quartz labyrinth flow reactor with immobilized photocatalyst bed. The rate of color removal can range as follows: AR18 > DG99 > AY36. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Photocatalytic Carbon-Nanotube,TiO2 CompositesADVANCED MATERIALS, Issue 21 2009Karran Woan Abstract The literature and advances in photocatalysis based on the combination of titania (TiO2) and carbon nanotubes is presented. The semiconductor basis for photocatalysis is introduced for anatase and rutile. Furthermore, the proposed mechanisms of catalytic enhancement resulting from the pairing of the titania semiconductor with either metallic, semiconducting, or defect-rich carbon nanotubes (CNT) is discussed. Differences are apparent for the mixtures and chemically bonded CNT,TiO2 composites. The article then highlights the recent advances in the synthesis techniques for these composites and their photocatalytic reactions with organic, inorganic, and biological agents. Finally, various applications and challenges for these composite materials are reported. [source] Characterization of a photocatalytic reaction in a continuous-flow recirculation reactor systemJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2006Fumihide Shiraishi Abstract A continuous-flow recirculation mode, generally called a recycle mode, is known to be practically meaningless except when the reactant is separated from the product at the reactor exit or when the reaction is autocatalytic, because when simply circulating a small amount of the fluid containing a reactant, the reactant concentration in this mode is lowered due to mixing of the fluid at the reactor entrance, leading to a decrease in the conversion at the reactor exit. This mode may, however, be meaningful in photocatalytic reactions with very large film-diffusional resistance. To indicate the validity of this estimation, therefore, characteristics of a continuous-flow recirculation reactor have been investigated both theoretically and experimentally. As a result, it is found that by increasing the circulation flow rate the conversion and productivity in this reactor is higher than that in a continuous-flow reactor because the film-diffusional resistance is remarkably reduced. Copyright © 2006 Society of Chemical Industry [source] Heterometal Alkoxides as Precursors for the Preparation of Porous Fe, and Mn,TiO2 Photocatalysts with High EfficienciesCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2008Xiao-Xin Zou Abstract Transition-metal-doped titanium glycolates (M,TG, with M=Fe, Mn), which are the first non-stoichiometric heterometal alkoxides, have been synthesised through a solvothermal doping approach. X-ray diffraction, UV/Vis diffuse reflectance and ESR spectroscopy revealed that the dopant ion (Fe3+ or Mn2+) is substituted for Ti4+ in the TG lattice. Fe3+ prolongs the crystallisation time of Fe,TG, whereas Mn2+ has a smaller effect on the crystallisation time in comparison with Fe3+. The as-synthesised M,TG materials were used directly as single-source precursors for the preparation of metal-doped titania (M,TiO2) through a simple thermal treatment process. The as-prepared M,TiO2 materials maintain the rod-like morphology of the precursors and possess a mesoporous structure with high crystallinity. It has been proved that the dopant ions are incorporated into the TiO2 lattice at the Ti4+ positions. The photocatalytic activities of the M,TiO2 materials obtained were evaluated by testing the degradation of phenol under UV irradiation. From the photocatalytic results, it was concluded that high crystallinity, a large surface area and appropriate transition-metal-doping are all beneficial to the enhancement of the photocatalytic performance of the doped TiO2 material. In addition, it was noted that in comparison with Mn,TiO2, Fe,TiO2 shows higher photocatalytic activity due to the better inhibition effect of Fe3+ on recombination of photogenerated electron,hole pairs. In contrast to the conventional nanosized TiO2 photocatalyst, the micrometre-sized M,TiO2 particles we obtained can be easily separated and recovered after the photocatalytic reactions. [source] | |||||||||||||