Preparation And Characterization Of Monodisperse Spherical TiO₂ By Hydrolysis

Spherical TiO2 is a kind of functional material with excellent performance.It has good fluidity,good mutual solubility and large specific surface area.It also has the characteristics of optimum whiteness,strong achromatism and excellent anti-ultraviolet light ability.Therefore,titanium dioxide with different particle sizes can be widely used in pigments,ink,papermaking,cosmetics,chemical fibers,metallurgy,photocatalysis,electronic and other fields.At present,the preparation methods of spherical TiO2 are mainly based on high cost methods such as sol-gel method and hydrothermal method.Although the cost of hydrolysis is low,there are still some problems such as poor particle dispersion and difficult particle size control.In this paper,Low-cost TiOSO4 solution was used as raw material to optimize the hydrolysis conditions of titanium solution at atmospheric pressure,and the hydrolysis process and particle formation process were studied in detail.The relevant parameters of the preparation of monodisperse spherical TiO2 and its particle size controllable process were determined.In addition,the preparation of monodisperse spherical TiO2 by hydrolysis of high concentration titanium solution was studied,which provided reference for the industrial production of monodisperse spherical TiO2 by hydrolysis.Firstly,the optimum technological parameters for hydrolysis of TiOSO4 were obtained as follows:acidity coefficient F value 1.7-1.8,volume ratio of titanium solution to bottom water 5:1,maturation time 20 min and hydrolysis time 3 h.The hydrolysates was secondary aggregates consisting of spherical primary particles.The size of secondary aggregates can be adjusted by controlling hydrolysis conditions.F value and bottom water amount are the main influencing factors in the induction stage and the whole precipitation process.The influencing factor in the pre-hydrolysis stage is aging time,and the influencing factor in the mature stage of hydrolysis is the hydrolysis time.In isopropanol dispersion solvent system,spherical titanium dioxide with uniform particle size distribution and good dispersion was obtained by hydrolysis of low concentration titanium solution using PVP as surfactant.The optimal volume ratio of isopropanol to titanium solution was 1:1,and the optimal volume of PVP was 5-10 g/L.The effects of titanium concentration,hydrolysis temperature,hydrolysis time,stirring rate and heating rate on the particle size of monodisperse spherical TiO2 were investigated.The results showed that titanium concentration and hydrolysis temperature had the greatest influence on the particle size.Spherical TiO2 particles with good dispersion and small particle size were easily obtained at lower titanium concentration and hydrolysis temperature.The optimum hydrolysis time was conducive to the uniformity of particle size.The optimum hydrolysis time was 2 h.The stirring rate has no obvious effect on the particle size of monodisperse system.The optimum stirring rate was 200 r/min.The products with small particle size and narrow particle size distribution could be obtained more easily with faster heating rate.Monodispersed spherical TiO2 with controllable particle size ranging from 0.1 to 1 micron could be prepared by changing hydrolysis conditions.In the study of preparation of spherical TiO2 by hydrolysis of high concentration titanium solution,it was found that the optimum amount of surfactant and hydrolysis temperature changed with the increase of titanium concentration.But when the titanium concentration exceeded a certain value,spherical TiO2 with regular morphology and good dispersion could not be obtained.Monodisperse spherical TiO2 particles were obtained by hydrolysis of 60 g/L high concentration titanium solution,and the optimum concentration of PVP was 25 g/L,hydrolysis temperature was 70℃.