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Influence of paint components on photoactivity of P25 titania toward NO abatement

2011; Elsevier BV; Volume: 96; Issue: 5 Linguagem: Inglês

10.1016/j.polymdegradstab.2011.01.032

1873-2321

C. Águia, Joana Ângelo, Luı́s M. Madeira, Adélio Mendes,

Advanced Photocatalysis Techniques

The present work studies the interference of paint components on the photoactivity of P25 photocatalyst toward NO abatement. Paint components are divided in two major groups: powder inorganic components and organic components. Two types of films were prepared, powder pressed films and films made of pseudo-paints, and their photoactivity assessed following approximately standard ISO 22197-1:2007(E). Powder pressed films were obtained by stepwise mixing powder components of the base paint; pseudo-paint films involved mixing the powder components stepwise with families of organic components present in the original photocatalytic paint formulation. It was concluded that the morphology of powder pressed films influences the photoactivity while CaCO3 and silicates, which are extenders, have a smaller impact on P25 photoactivity compared to pigmentary TiO2. Pseudo-paint films containing the same proportion of powder components as powder pressed films displayed different transient behaviors but similar steady-state photo-activities, regardless the presence of organic components such as the binder. This was assigned to the photo-erosion of a significant fraction of the organic paint components during the transient period. Therefore, after reaching steady-state, NO photooxidation could proceed freely as if only inorganic paint components were present. An average of ca. 25 wt.% of organic phase erosion was observed but more severe erosion should occur closer to the top of the paint film.