THE EFFECT OF NANOSIZED TITANIA-SILICA FILM COMPOSITION ON THE PHOTOSTABILITY OF ADSORBED METHYLENE BLUE DYE

The effect of nanosized porous films (average density 10 g/m2) of TiO2. TiO2/SiO2, and SiO2 on the photostability of adsorbed methylene blue (MB) dye during UV irradiation in air was investigated by optical spectroscopy and laser-induced mass spectrometry. The effectiveness of the photodecomposition of MB decreases in the order TiO2 > TiO2/SiO2 > SiO2 with rate constants 1E-2, 0.6E-2, and 0.3E-2 min–1 respectively. A mechanism including the participation of both excited states of the dye molecules and photoexcited titanium dioxide is proposed for the photodecolorization of MB adsorbed on the surface of the investigated films.