Preparation of Photocatalytic Coatings Adapted to the Elimination of Airborne Pollutants: Influence of the Substrate on the Degradation Efficiency

摘要

Immobilized TiO2 is required for most photocatalytic applications, but obtaining the adequate mechanical and chemical resistance without compromising activity can be very challenging. In order to gain further information about the effect of the substrate on photoactivity, the influence of their physicochemical properties on the efficiency of TiO2 coating for photocatalytic air purification has been studied in this work. With this aim, two different chemicals, hydrogen sulfide (H2S) and trichloroethylene (TCE), were selected as model pollutants to determine the behavior of photoactive layers under diverse experimental conditions. Hydrogen sulfide is a widespread compound, which not only causes nuisance due to its unpleasant odor, perceptible at very low concentrations (>0.5 ppb_v), but is also responsible for corrosion in devices and materials. In this work, the efficiency for H2S photocatalytic degradation was compared for TiO2 coatings deposited on different UV-transparent substrates: borosilicate glass and two organic polymers, polyethylene terephthalate (PET) and cellulose acetate (CA). In addition, TiO2 was deposited on plates made of either borosilicate glass, or natural magnesium silicates, and the performance of these immobilized photocatalysts was determined for the elimination of trichloroethylene (TCE), as a model pollutant. Comparison of the activity of TiO2 deposited on this ceramic support, with that of TiO2 deposited on glass can provide valuable information about the influence of the substrate porosity on the photocatalytic efficiency. Results presented indicate that TiO2 on sepiolite can be regarded as a hybrid photocatalyst, which combines adsorptive and photocatalytic properties.