Photocatalysis: from fundamentals to self-cleaning glass applications

Autores: Herrmann, J.M.|Péruchon, L.|Puzenat, E.|Guillard, C.
Fuente: BAGLIONI, P.; CASSAR, L. (EDS.) International RILEM symposium on photocatalysis, environment and construction. Bagneux: RILEM, 2007.
p. 41-48

Photocatalysis only requires photonic energy activate th esolid (TiO2) by contrast with conventional catalysis which requires heat for thermo-activation. This is the basical advatage of photocatalysis for a large variety of environmental applications. Self-cleaning glass technology consists in depositibg sub-micronic (i.e. invisible) thin layers of titania at the surface glass, without decreasing sub-micronic (i.e. invisible) thin layers of titania at the surface of glass, without decreasing light tramittance. The photocatalytic activities of these titania layers can be carefully determined «in vitro!», using calibrated test-reactions such as the total degradation of malic acid in water or that of palmitic and stearic acids in the adsorbed phase. Test based on dyes decolorization can be misleading.
In the real world, dirty glasses to be «self-cleaned» are soiled by greasy and sticky deposits, which, in addition, induce a string adherence of ambient dusts. To mimic that, self-cleaning glasse were covered with palmitic and stearic acids. The linear aliphatic hydrophobic chains are progressively «peeled off», carbon atom after carbon atom, via successive by by-passing many intermediates via the release of several volatile ones.
The efficiency of titania photocatalyst demands two requirements: a good cristallinity (anatase phase) and a high (cationic) purity.