Preparation Of TiO2-SiO2 composite photocatalysts for environmental applications.

International audienceBACKGROUNDThe objective of this work is to prepare various TiO2/SiO2 composites, determine their photocatalytic activity and suggest the most promising materials for further application.RESULTSTiO2/SiO2 composites were successfully prepared as a powder, obtained by the heterocoagulation of mixed TiO2 and SiO2 aqueous colloidal suspensions. The heterocoagulation of prepared amorphous TiO2 in the presence of SiO2 led to the crystallization of TiO2 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 SiO2 increased the rate of degradation of Methylene Blue in comparison with pure TiO2 in acidic conditions, whereas Acid Orange 7 photodegradation was faster in basic solution in the presence of TiO2/SiO2 1:1 composite. In gaseous phase, composites prepared by heterocoagulation showed improved photoactivity (conversion around 35%).CONCLUSIONComposites prepared by heterocoagulation with ratio TiO2/SiO2 1:10 can be used as photocatalyst in self-cleaning paints. SiO2 partly covers the TiO2 surface and acts as a barrier which separates the active surface of TiO2 from contact with the binder or polymeric substrate