Impact of rutile and anatase phase on the photocatalytic decomposition of lactic acid

Rutile TiO2 photocatalysts with high surface area were synthesized by hydrolysis of TiCl4 in aqueous solution during 2 h and 48 h and either treated at 300 degrees C or not. These samples of home-made rutile TiO2 were characterized by X-ray diffraction (XRD), electron microscopy (ESEM and TEM), BET surface area analysis, TG-DTA-MS and UV-vis diffuse reflectance spectroscopy. All four home-made (HM) TiO2 photocatalysts are nanorods of pure rutile TiO2 with surface areas between 92 and 173 m(2)/g. The photocatalytic efficiencies of HM rutile samples were compared with those of commercial rutile, anatase and mixed anatase/rutile towards the degradation of lactic acid (LA), and discussed in regards to the adsorption sites. Our results showed (i) it is possible to obtain a rutile TiO2 more efficient than TiO2 P25 and (ii) the time of hydrolysis and calcination have an important impact on photocatalytic efficiency. The analysis of organic intermediates present in aqueous and gaseous was also performed. At similar LA conversion, high pyruvic acid selectivity was observed only in the case of the two commercial rutile TiO2 samples.