Preparation of TiO 2 ‐ SiO 2 composite photocatalysts for environmental applications

BACKGROUND The objective of this work is to prepare various TiO 2 / SiO 2 composites, determine their photocatalytic activity and suggest the most promising materials for further application. RESULTS TiO 2 / SiO 2 composites were successfully prepared as a powder, obtained by the heterocoagulation of mixed TiO 2 and SiO 2 aqueous colloidal suspensions. The heterocoagulation of prepared amorphous TiO 2 in the presence of SiO 2 led to the crystallization of TiO 2 with anatase structure. Photocatalytic activity was tested in the liquid phase by dye degradation and in the gas phase by hexane degradation. In aqueous phase the presence of SiO 2 increased the rate of degradation of Methylene Blue in comparison with pure TiO 2 in acidic conditions, whereas Acid Orange 7 photodegradation was faster in basic solution in the presence of TiO 2 / SiO 2 1:1 composite. In gaseous phase, composites prepared by heterocoagulation showed improved photoactivity (conversion around 35%). CONCLUSION Composites prepared by heterocoagulation with ratio TiO 2 / SiO 2 1:10 can be used as photocatalyst in self‐cleaning paints. SiO 2 partly covers the TiO 2 surface and acts as a barrier which separates the active surface of TiO 2 from contact with the binder or polymeric substrate. © 2014 Society of Chemical Industry