Photodegradation kinetics of stearic acid on UV-irradiated titania thin film separately followed by optical microscopy and Fourier transform infrared spectroscopy

M.N. Ghazzal, N. Barthen, N. Chaoui

    Résultats de recherche: Contribution à un journal/une revueArticleRevue par des pairs

    Résumé

    We use optical microscopy for observing the photocatalytical decomposition of SA on titania film during exposure to a simulated solar illumination. The titania films were prepared via sol-gel and deposited on a borosilicate glass substrate by dip-coating. A low amount of SA was deposited by dipping the titania film in a methanolic SA solution. Optical micrographs showed that the deposited SA forms islands with variable heights and sizes and that upon UV-irradiation, these latter decomposed gradually from the edges towards the center. The SA photodecomposition as evaluated by measuring the integrated IR absorbance of SA in the 2700-3000cm region, proceeded according to a pseudo first-order kinetics with respect to SA. By contrast, it was of the zero-order type when monitoring the decomposition of an individual SA island by microscopy. From these results, we showed that the pseudo first-order kinetics is the result of a collective effect of many independent and parallel zero-order reactions with variable durations. This scenario describes well both the experimental data and those reported in literature.
    langue originaleAnglais
    Pages (de - à)85-90
    Nombre de pages6
    journalApplied Catalysis B: Environmental
    Volume103
    Numéro de publication1-2
    Les DOIs
    Etat de la publicationPublié - 14 mars 2011

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