Photocatalysis Of Rhodamine 6g Degradation In Aqueous Media By Tio2/sio2 Nanocomposites
PHOTOCATALYSIS OF RHODAMINE 6G DEGRADATION IN AQUEOUS MEDIA BY TiO2/SiO2 NANOCOMPOSITES
N. Smirnova, A. Eremenko, E. Migunova, O. Linnik,
O. Yakimenko, V. Ogenko
Institute of Surface Chemistry of National Ukrainian Academy of Sciences, Kiev, Ukraine, e-mail: annerem@mail.kar.net
The utilization of semiconductor particulate systems as a reactive heterogeneous media have been and remains very popular in carrying out photochemical transformations of organic and inorganic compounds. Nanosized titania catalysts exhibit unique and efficient reactivity for various photocatalytic reactions in which many organic substrates have been shown to be oxidatively (in some cases reductively) degrade and ultimately mineralize completely under UV irradiation. In the focus of our investigation is the self-photosensitized pathway, when colored substrate itself acts as a sentizer and initiates its own degradation. The advantage of this process is the utilisation of visible light for degrading colored pollutants. Mixed oxide composite materials can often be more efficient photocatalysts than pure substances.
In this study, we deal with the preparation of porous TiO2 /SiO2 (10 - 30 wt% of titania) films and powders using the sol-gel method. Cetiltrimetilammoniumbromide (CTAB) was used as template, TEOS - as framework source, TTIP (TS-1) or concentrated TiO2 colloid contained anatase nanoparticles (TS-2) were used as titania sources.
The photocatalytic properties of sol-gel derived films were assessed by measuring the photodegradative oxidation of Rod 6G in water solutions under UV and visible light and compared with Degussa P-25 coated films.
TiO2 /SiO2 films, contained matrix-isolated anatase nanoparticles (TS-2) showed the improved photocatalytic activity toward Rod 6G decomposition relative to TS-1 and P-25 films under UV as well as visible irradiation. Liquid-phase reaction is very effective in contrast to gas-phase oxidation, where mobility of photogenerated intermediates is limited. Effect of synthesis conditions of titania-silica binaries – their chemical composition, homogeneity and texture, crystal structure of TiO2 particles on the photocatalytical activity will be discussed.
Related articles::