Hydrothermal preparation of high purity TiO₂ from industrial metatitanic acid by response surface methodology

The response surface methodology of Box Behnken design was used to investigate the effects of hydrothermal conditions on the high purity TiO₂ preparation from industrial metatitanic acid. The method had a good fitting result in the prediction model, and the effects could be calculated from a second-order polynomial equation. The hydrothermal conditions greatly affected the structure and purity for the metatitanic acid and rutile TiO₂, influenced the process of nucleation and crystallization, grain growth, polymerization, agglomeration and aggregation, further improved the particle size distribution, structure and surface adsorption capacity of metatitanic acid, reduced the adsorption of impurity ions, and finally improved the purity of TiO₂. The variables such as hydrothermal temperature, slurry concentration and hydrothermal time had synergistic effects, and the effects of hydrothermal time were larger than the other two. The verification experiments confirmed that the predicted values could be achieved at 99.99% under the optimal hydrothermal conditions.