Crystal size control of TiO2 using experimental strategies in sol-gel process

Titania photocatalysts were prepared in a sol-gel process by using tetraisopropyl orthotitanate and nitric acid as precursor and catalyst. Effects of the preparation variables on the crystal size and photocatalytic activity of TiO₂ were systematically examined using the fractional factorial design (FFD). The following preparation parameters were investigated in the present FFD analysis: amount of water, amount of nitric acid, amount of tetraisopropyl orthotitanate and calcination temperature. The polynomial models were developed from analysis of variance tables to connect the preparation conditions, crystal size and photocatalytic activity. Results indicated that the effect of calcination temperature and amount of nitric acid are the key factors influencing the crystal size and activity of TiO₂ particle. Based on the models, the anatase crystal size of TiO₂ from 6.7 to 29 nm can be controlled precisely by this process.