Preparation of Nano-TiO₂ by Stripping Precipitation Method and Photocatalytic Performance

Precursor of nano-TiO₂ was prepared through stripping precipitation method with D2EHPA diluted by tetrachloride carbon as an extractant,and ammonia and ammonia-alcohol aqueous solution as a re-ex- tractant and precipitator.This process was optimized by controlling mass transport process on the interfaces of microemulsions.Nano-TiO₂ obtained was characterized by SEM、XRD、Zeta potential devices.The result showed that catalytic performance was distinctly influenced by lowering temperature and concentration of ammo- nia aqueous,increasing concentration of ethanol auxiliary agent and varying calcinating temperature of TiO₂ sample.By stripping precipitation with ammonia and ammonia-alcohol,the optimum caleinating temperatures of TiO₂ were adjusted at 350℃and at 450℃respectively.The temperature and the optimum concentration of ammonia aqueous were 17.5℃and 1:5 respectively.The higher concentration of auxiliary agent was more beneficial to forming smaller and more uniform TiO₂ particles.Compared with sol-gel method,directing pre- cipitation method and stripping precipitation method with ammonia,this study showed that nano-TiO₂ pre- pared by stripping precipitation with ammonia-alcohol had not only a small and uniform grain,but also a high efficient photocatalytic activity,and the removal efficiency of methylene blue illuminated for 60 min with TiO₂ by stripping precipitation with ammonia-alcohol was above 85 %.