10 research outputs found

    TiO2 photocatalysis of the organophosphorus Fenamiphos : insight into the degradation mechanism.

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    International audienceThe photocatalytic degradation of the organophosphorus fenamiphos (FN) was studied using titanium dioxide as a photocatalyst and 365 nm as an excitation wavelength. Under our experimental conditions and in aerated solutions, the irradiation in the presence of TiO2 P25 (1.0 g L−1) permitted the evaluation of the half lifetime to 9.5 minutes. Laser flash photolysis experiments showed the formation of an initial species owing to the attack of the hydroxyl radical on FN. It was identified as the adduct -FN. The second order rate constant for its formation was evaluated to moL−1 L s−1. All the products are formed via the formation of such transient intermediate. They were identified by means of HPLC/MS using electrospray in positive mode ( ). Two main processes are responsible for FN photocatalytic transformation: (i) hydroxylation on the aromatic structure and (ii) the scission of the C-O bond. A mechanistic scheme was proposed for the photocatalytic process of FN using titanium dioxide. An efficient mineralization was observed within 24 hours by using a suntest setup

    Fabrication of TiO2 Nanotube by Electrochemical Anodization: Toward Photocatalytic Application

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    In this study, a self-organized nanotubular titanium dioxide (TiO2) array was successfully produced by anodizing pure titanium in a mixture of glycerol, distilled water (8% vol.), and ammonium fluoride using a dual electrode system. The size control and distribution of the nanopores were performed in a DC voltage range varying from 30 V to 60 V. The diameter of TiO2 nanopores varies from 59 to 128 nm depending on the anodizing voltage. Energy-dispersive X-ray spectroscopy (EDX) analysis reveals that the as-prepared films are essentially composed of TiO2. According to the X-ray diffraction (XRD) and Raman spectroscopy analysis, the nanotubular arrays of TiO2 annealed at 600°C for 2 hours are composed of a phase mixture of anatase and rutile. Mott-Schottky analysis showed that the TiO2 nanotubes are consistent with an n-type semiconductor with a donor density of about 1017 cm-3. Preliminary results on the photocatalytic degradation of a pharmaceutical pollutant showed that the TiO2 nanotubes can be used as a promising material for application in wastewater treatment
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