Preparation and characterization of TiO2 aerogels for use as photocatalysts

Abstract The preparation and morphological properties of TiO2 aerogels and cryogels prepared by the sol-gel method are described. Materials were prepared by acid catalyzed sol-gel technique, using different reactant compositions and drying procedures. The morphological effects of preparation conditions such as reactant composition, gel wash, drying and air-annealing are described. It was found that gels prepared by using a ratio of 1:20:3:0.08 between Ti:Ethanol:H2O:nitric acid are the clearest and the most stable. These TiO2 aerogels have a porosity of 90%, BET surface areas of 600 m2/g and total pore volume of 1.8 cm3/g. Adsorption and photodecomposition profiles of salicylic acid, which was used as a model reaction, are described. It is shown that at equilibrium, aerogels adsorb about ten times more salicylic acid than the Degussa commercial powder does (350 vs. 40 μmol/g TiO2). It is shown that photo-degradation of salicylic acid on TiO2 aerogels, after 1 h of near UV illumination, is about 10 times faster than on the Degussa TiO2 powder.

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