Suchergebnisse

This work is aimed to select the best synthetic polymers available in the market with high transmittance in the TiO2 activation range that can be coated with the semiconductor and withstand the photocatalytic oxidation conditions. Among eleven commercial organic polymers with different additives and processing techniques, only polypropylene, polystyrene, sheet moulding processed poly (methyl methacrylate) and rigid polyvinyl chloride presented transmittances higher than 80% at 360 nm , which allows irradiation there through. The selected polymers were coated without a calcination step with anatase-TiO2 obtained by sol-gel. Their weathering was studied during 150 days of exposure to solar radiation, with and without the TiO2 layer. It was observed that only poly (methyl methacrylate) retains the titania and the good optical and mechanical properties after the natural weathering, and thus is the best candidate for immobilization of TiO2 for air photocatalytic treatment applications. ; The authors are gratefully acknowledged to the Spanish Government for the financial support (CMT2011-25093 and Juan de la Cierva postdoctoral contract of R.P.), to E. Espí for the polyolefin samples, to F. Fernández for the XRD analysis and to A. Ochoa for the strength tests. ; Peer reviewed

The photocatalytic elimination of microorganisms from indoor air in realistic conditions and the feasibility of simultaneous elimination of chemical contaminants have been studied at laboratory scale. Transparent polymeric monoliths have been coated with sol-gel TiO 2 films and used as photocatalyst to treat real indoor air in a laboratory-scale single-step annular photocatalytic reactor. The analytical techniques used to characterize the air quality and analyze the results of the photocatalytic tests were: colony counting, microscopy and PCR with subsequent sequencing for microbial quantification and identification; automated thermal desorption coupled to gas chromatography with mass spectrometry detection for chemical analysis. The first experiments performed proved that photocatalysis based on UVA-irradiated TiO 2 for the reduction of the concentration of bacteria in the air could compete with the conventional photolytic treatment with UVC radiation, more expensive and hazardous. Simultaneously to the disinfection, the concentration of volatile organic compounds was greatly reduced, which adds value to this technology for real applications. The fungal colony number was not apparently modified. © 2012 Elsevier Ltd. ; Spanish Government for financial support (TRA2009_0262_01 (TRACE) and CTM2008-06876-CO2-01/TECNO (IndoorAir)) ; Peer Reviewed