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 center dot 2H(2)O 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 center dot 2H(2)O, so the composite structure of hydrated-titanium-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 inter-layer 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 degrees C is smallest and reaches 13.4 nm. After calcination at 1100 degrees 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 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.