Hydrothermal And Microwave Hydrothermal Synthesis Ultrafine Nano Tio <sub> 2 </ Sub>

A series of ultrafine nano TiO₂ catalysts have been synthesized by hydrothermal or microwave-hydrothermal method based on traditional peptization process, using titanium tetrachloride as material, polyacrylic acid(PAA) as modifying agents. The obtained samples were characterized via XRD, BET, TEM and XPS methods in detail.The effects of the hydrothermal conditions and the PAA content on the structure of TiO₂ were investigated. The photocatalytic activity of ultrafine nano TiO₂ was studied by degradation of the Rhodamine B(RhB) , toluene and acetaldehyde, respectively. The optimum preparation conditions were determined as hydrothermal treatment at 180℃for 8h, the PAA content of 12%, and microwave-hydrothermal treatment at 180℃for 30min, the PAA content of 15%.The characterization results suggested that both hydrothermal treatment and microwave-hydrothermal treatment can improve the crystallization of TiO₂, and PAA can effectively control the growth and agglomeration of TiO₂ particles. XRD and TEM results indicated that the average diameter of TiO₂ particles were 9¹3nm, the main phase was anatase with highly crystallinity, and ultrafine nano TiO₂ had good dispersity. XPS results showed that the content of surface hydroxyl, adsorption oxygen and oxygen vacancies on the surface of the treated TiO₂ was increased remarkably, which would lead to better photocatalytic activity.The TiO₂ samples, by which were prepared under the two optimized conditions, could photocatalytic degrade RhB efficiently, and the degradation rate reached 85% and 89% respectively, much higher than P25. Furthermore, it also exhibited high photocatalytic activity to toluene and acetaldehyde.