Effects of pH Value on Composite Structure of Poly-titanium-ion/Montmorillonite and Its TiO₂ Nano-particle

The montmorillonite composite structure samples were prepared using a hydrolysation-intercalation composite method with TiOSO4·2H2O as a precursor of TiO2 nano-particles and montmorillonite as substrate by controlling the pH value of the montmorillonite suspension. The changes of the structure, phase and crystal size of the samples were characterized by X-ray diffraction method. The results show that the pH value of montmorillonite suspension has a significant influence on the hydrolyzation of TiOSO4·2H2O, so the composite structure of hydratedtitanium-oxide/montmorillonite is affected. When the pH value of montmorillonite suspension is 0.5, the poly-titanium-ions are with the lower electrovalence and extent of polymerization and easily intercalate the interlayer space of montmorillonite, moreover, the structural layers of montmorillonite are separated best. The crystal size of anatase in the TiO2/montmorillonite composite samples calcinated at 700°C is smallest and reaches 13.4 nm. After calcination at 1100°C, the relative content of anatase in the composite structure reaches 35%. Compared with pure TiO2 nano-particle sample, TiO2/Montmorillonite composite sample has a higher phase transition temperature 第 12期 吕 霞, 等: pH值对聚合钛离子/蒙脱石复合结构及其 TiO2纳米粒子属性的影响研究 1295 from anatase phase to rutile phase and smaller crystal size of TiO2. Montmorillonite structure layer has a significant blocking effect on the TiO2 phase transformation and grain growth.