0000000000147272

AUTHOR

José C. Conesa

Photoreactivity of Iron-Doped Titanium Dioxide Powders for Dinitrogen Reduction to Ammonia

The production of NH3 from N2 and H2O on Fe/TiO2 has been studied in a continuous photoreactor under UV radiation. An ESR study of the catalysts shows that Fe3+ ions are better electron traps than Ti4+ ions. This trapping can be irreversible if the corresponding holes originate stable species adsorbed on the catalyst surface. The charge separation, thus favoured by the Fe3+ ions, helps the N2 adsorption by its reaction with surface species activated by holes. The best activity is found when no excess Fe is segregated at the surface; overall turnover for N2 reduction as high as 6 e−/Fe atom can be reached before catalyst deactivation.

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Photocatalytic inactivation of Legionella Pneumophila and aerobic bacteria consortium in water over TiO2/SiO2 fibres in a continuous reactor

A continuous photoreactor, working in a total recycle mode and irradiated by a low-pressure Hg lamp, has been used to study the bactericidal effect of a photocatalyst, formed by TiO2 embedded in SiO2 fibres, on Legionella pneumophila and a consortium of common gram-negative aerobic bacteria: (Escherichia coli, Klebsiella sp., Pseudomona sp. and Proteus sp.) in water. The kinetic modeling of the inactivation process, carried out with the measured values of viable bacteria concentration at the outlet of photoreactor, evidenced that for each pass inside the photoreactor the ratio between the outlet and inlet cell concentrations was of order of 0.01 for the inactivation of L. pneumophila. For t…

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ESR study of photo-oxidation of phenol at low temperature on polycrystalline titanium dioxide

The formation of oxygen radicals on hydrated TiO 2 (anatase) samples irradiated at 77 K in the near-UV region and their interaction with adsorbed phenol molecules have been studied by electron spin resonance. The results indicate that the irradiation determines the generation of O 2 H · and O − radicals which react with adsorbed phenol molecules. Phenol-derived radicals are generated after warming the sample at room temperature. A reaction mechanism is proposed on the basis of the observed species.

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Fourier Transform Infrared Study of the Performance of Nanostructured TiO2 Particles for the Photocatalytic Oxidation of Gaseous Toluene

Thermal and hydrothermal treatments have been applied to an amorphous TiO2 precursor for obtaining nanosized TiO2 particles (P11t and P11h, respectively) of different photocatalytic properties. The activity of these catalysts has been tested by performing the toluene oxidation in gas phase in a continuous photoreactor. A Fourier transform infrared (FTIR) investigation of the catalysts under conditions prevailing during the test photoreaction has also been carried out. The photoreactivity results showed that CO2 was the main oxidation product and benzaldehyde a stable intermediate. Anatase P11t photoactivity was similar to that observed for commercial photocatalysts, while anatase P11h prese…

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