Effects and optimization of hydrolysis conditions on the diameter distance ratio for metatitanic acid

Controlling and predicting the narrow particle size distribution of metatitanic acid could help to improve pigment and application performances of TiO₂. To prepare metatitanic acid with narrow particle size distribution, the hydrolysis conditions of industrial TiOSO₄ solution were optimized by using the response surface methodology of Box-Behnken design method. The effects of hydrolysis conditions such as TiO₂ concentration, aging time and hydrolysis time on the diameter distance ratio and structure of metatitanic acid were investigated. The prediction model including the hydrolysis variables with good fitting result was established to predict the diameter distance ratio or optimize the hydrolysis variable values. The regression equation model was significant and reliable with actual correlation coefficient R² of 0.9989. The hydrolysis conditions greatly influenced the quality and quantity of hydrolysis induced crystal nucleus, hydrolysis rate, completeness degree of hydrolysis, crystallization growth and aggregation rate, and eventually affected the particle size distribution of metatitanic acid. The synergistic interaction for TiO₂ concentration and hydrolysis time was very significant. The verification experiments confirmed that the diameter distance ratio could reach the average value of 1.100 under the optimal conditions. The prepared metatitanic acid had anatase TiO₂ phase structure, with average particle size of 1.621-1.819 µm. And this helped to improve the high quality and green development of the titanium dioxide industry.