Effects of hydrothermal temperature and acid concentration on the transition from titanate to titania

Nanostructured titanates were prepared by alkaline hydrothermal processing. The titanates were transformed to the anatase particles at low concentrations of acid, whereas the rutile rods were produced from the titanates at high concentrations of acid. These changes were more retarded in the titanate nanofiber product than in titanate nanotubes product, which could be attributed to the stability and high crystallinity of the titanate nanofiber product prepared at a high hydrothermal temperature. The photocatalytic activities of the acid treated nanostructured titanates for MB degradation and gaseous CH3CHO oxidation were strongly dependent on the presence of the anatase crystalline phase.