Photodecomposition of Methylene Blue by TiO_2-mounted Diatomite

TiO_2-mounted diatomite photocatalysts were prepared by a sol-gel method with diatomite support,a kind of natural biological diatomaceous silica earth.SEM observation shows that TiO2 is well mounted on the surface of diatomite as films and some particles. TiO2-mounted diatomite decomposes efficiently methylene blue (MB) under UV irradiation.Within 36h irradiation,about 90% MB is decomposed by TiO_2/diatomite photocatalyst.After 48h irradiation,MB is decomposed ahnost completely (about 98%).However only 35% MB is decomposed by pure diatomite after 48h irradiation. With the increasing heat-treatment temperatures,the photocatalytic activity of the TiO_2/diatomite is increased with the formed anatase type of TiO_2 increasing,but decreased with rutile type of TiO_2 formed at 700℃C and 900℃.Adding H_2O_2 in MB solution can improve the efficiency of the TiO_2- mounted diatomite photocatalysts greatly.