Lifecycle of commercial photocatalytic nanocoatings : nanoparticles aerosol emission during mechanical and environmental stresses application
Résumé
In the present work, we investigate the effect of the mechanical stresses and weathering duration on two commercial photocatalytic nanocoatings for their nanoparticle emission tendency into ecosystem. The emission is studied in terms of number concentration, size distribution, shape and chemical composition of the nanoparticles. It is found that depending upon the type of product design, the two nanocoatings appear to exhibit contrastingly opposite behavior in terms of the nanoparticles emission. Increase in weathering duration results in stepwise structural deterioration of the nanocoating, which in turn decreases the nanocoating life, changes the nanocoating removal mechanism, and increases the nanoparticles emission concentration. Emission of free TiO2 nanoparticles is found to be weathering duration dependent. Three quantities are introduced too: emission transition pace (ETP), stable emission level (SEL), and stable emission duration (SED). By linear extrapolation of these quantities from short weathering durations, complete failure of the nanocoatings can be predicted and, moreover, the potential increase of nanoparticles release into the air.