Doped Nano Tio <sub> 2 </ Sub> Photocatalytic Degradation Of Formaldehyde

The formaldehyde is one of organic contamination that disserves severely daily lives and health.It's important to degrade formaldehyde with a effective photocatalyst.The nano-TiO₂ semicondutor is of excellent properties such as security,un-poisonous,high activity,chemical stability and low cost et al,so it was selected as photocatalyst to degrade formaldehyde.The photocatalyst were prepared by a Sol-Gel method.The microstructure of nano-TiO₂ is characterized by XRD,SEM,TEM,Uv-vis et al.Many aspects including the synthetic technology parameters and the relations of the effection factors with catalyst activity were investigated in this research.In order to expand the spectrum response range of nano- TiO₂ ,La³⁺ and Ce³⁺ were doped in the preparation of the specimens which both were selected as photocatalyst to degrade formaldehyde.Via the study of the preparation process and the photocatalytic experiment,the results were obtained as follows:(1) The crystal structure of Anatase is transformed to that of Rutile with the incresse of the clacining temperature.The phase compositions of nano- TiO₂ photocatalyst are Anatase at 400℃,Anatase + Rutile at 450℃and Rutile at 700℃holding 2h.(2) The experiment shows that the specimen of Anatase + Rutile prepared at 450℃holding 2h has higher photocatalytic activity to formaldehyde.(3) The phase transformation can be controlled by the dopations of La³⁺and Ce³⁺ in the nano- TiO₂. The photocatalysts of nano- TiO₂ doped 2% La³⁺ and 3% Ce³⁺ have better photocatalytic activity respectively when the doped ions concentration from 0.5%wt to 4%wt.(4) The nano- TiO₂ doped with Ag⁺ has effective action against colon bacillus and staphylococcus aureus.