Preparation of TiO2 coatings on PET monoliths for the photocatalytic elimination of trichloroethylene in the gas phase

This paper presents the first data on the performance of polyethylene terephthalate (PET) monoliths as photocatalytic support. For this purpose, first a protective layer of SiO₂ was applied to the polymer to prevent oxidation of the substrate, and subsequently the photoactive layer of TiO₂ was deposited on PET monoliths using the dip-coating technique. In order to increase the adherence of inorganic coatings, two different synthesis procedures were evaluated. One approach was based on reducing the surface tension of the SiO₂ sol using a fluorinated surfactant to increment the PET wettability. The second approach consisted in modifying the PET surface with a layer of the polymer poly(diallyldimethylammonium) chloride (PDDA), which provides a positively charged surface for the fixation of the alkaline SiO₂ sol. Both TiO₂/SiO₂ coated PET monoliths were assayed in a single-pass annular reactor for the destruction of trichloroethylene (TCE). The two coating procedures were compared in terms of homogeneity, durability and photocatalytic activity.