Study on the Photocatalytic Degradation of Bisphenol a by La3+ Doping TiO2 under Sunshine Irradiation

Lanthanum doping TiO2 powders were prepared using sol-gel method, and characterized by XRD. The doping quantity, time of solar irradiation and the added quantity of catalyst were investigated for the influence on the photocatalytic degradation of bisphenol A. The results show the structure of La3+ doped TiO2 powders were anatase, particle size were 16 nm. For the initial concentration of bisphenol A solution were 50 mg/L , when the doping quantity of La were 1.0 wt %, the dosing quantity of TiO2 were3.6 g/L, PH value were acid, irradiation time were 2 h, the photocatalytic activity of TiO2 was the best.

HRTEM Study of Phase Transformation from Anatase to Rutile in Nanocrystalline TiO2 Particles

The spherical anatase TiO2 nanoparticle of 50 nm in diameter was manufactured by flame method and was subsequently heat-treated to investigate the transformation behavior from anatase to rutile using TEM observation. The anatase particle was facetted at the free surface and a neck formed between the anatase particles prior to the phase transformation. This resulted in the severe lattice distortion at the region of the interface. Unfortunately, we could not find the rutile grain nucleated in the anatase particle due to very fast grain growth. All the phase boundaries observed in HRTEM images existed in the contact between anatase and rutile particles. The nucleation of rutile phase in anatase particle was suppressed at the low heat-treated temperature but the grain growth of rutile particles after the phase transformation grew very fast by the sweeping phenomena of grain boundary. It leaded to the microstructure without the rutile phase traped in anatase particle.