硫酸溶液中钛水解物晶型的控制

Phase Controlling of Hydrated TiO_2 Formed under Low Titanium Concentration in Sulfuric Acid Solution

对硫酸溶液中低钛浓度下钛水解产物晶型与水解条件的关系进行了研究.结果表明,通过调节硫酸钛溶液的加入速度和硫酸浓度,可控制水解物晶型.在100℃的2.5%(ω)硫酸溶液中,当硫酸钛溶液加入速度不高于2mL/h,主要生成金红石型TiO2;而当加入速度增至8mL/h或硫酸浓度增至不低于10%(ω)时,则主要形成锐钛矿型TiO2.水解速度较快的均相成核阶段较易生成锐钛型TiO2,而在晶核长大阶段,缓慢水解有助于形成酸性溶液中热力学上更稳定的金红石型TiO2.

The relationship between hydrolysis condition and phase of hydrated TiO2 formed at low titanium concentration in sulfuric acid solution was investigated. The results showed that the polymorphic phase of titanium hydrolysate could be controlled by adjusting the feeding rate of titanium sulfate stock solution and concentration of sulfuric acid. When the feeding rate of stock solution was below 2 mL/h in 2.5%（ω） sulfuric acid solution at 100 ℃, the hydrated titania was rutile, however, with that increasing to 8 mL/h, or the sulfuric acid concentration increasing to above 10%（℃）, the predominant phase switched to be anatase. The phase strongly depended on the rate and stage of hydrolysis. A rapid hydrolysis during homogeneous nucleation period generally led to the formation of an anatase hydrolysate. And in the nuclei growth stage slow hydrolysis process was beneficial to the formation of rutile, which was thermodynamically stable phase in acidic solution.