Nano Tio <sub> 2 </ Sub> Synthesis, Surface Treatment And Its Anti-reunification Research

Nanosized TiO₂ is a new type of functional material, is widely used in many industrial fields, such as metallic automotive coating, sunscreen cosmetics, dye sensitized solar cell, photocatalyst and so on. The application of nanosized TiO₂ is depended upon its microstructure, surface polarity and agglomeration. In this thesis, the research results was reported, including the synthesis of nano-titania with different phases, particle sizes and morphologies, surface modification of nanosized TiO₂ in rutile phase, anti-agglomeration of nano-particles TiO₂ in the wet process of its preparation. The main content was concluded as follows:1 On the basis of LTDRP, the nano-titania in rutile phase was obtained at low temperature using a improved method, and the traditional process to prepare rutile by calcining anatase at high tempreture was changed. Taking advantage of the hydrolysis of excessive TiCl₄, the process of washing and adding acid (hydrochloric acid or nitric acid) was left out, and the production cost of nanosized TiO₂ was saved. The effect of neutralization method, neutralization temperature, crystallization temperature, crystallization time, heating rate, the concentration of NaOH, n(NaOH):n(TiCl₄),and additive on crystal phase of TiO₂ powder was investigated. The formation mechanism of nanosized TiO₂ was discussed.2 The TiO₂ with different phases, morphologies and sizes was prepared by hydrothermal method. The results showed that the microstructure of nanosized TiO₂ was depended on not only hydrothermal conditions but also formed factors of precursor. When precursor was amorphous, pH_initial value was the key factor in determining the crystal phase, particle size and morphology of TiO₂ powder. When the range of pH_initial value was 9.00-12.00, the brookite TiO₂ with single phase was obtained at 200℃ for 24h. XRD and TEM revealed that brookite TiO₂ were composite particles assembled or combined by nanocrystalline. The hydrothermal temperature and time increased with pH_initial value in the transformation of amorphous TiO₂ to brookite phase. The higher pH_initial value was, the larger the crystallite size and particle size were. It was firstly found that the phase and morphology of TiO₂ powder was changed in presence of glycol or propanetriol. When V_glycol :Vwater =≤1:1 or V_propanetriol :Vwater≤1:3,the phase of TiO₂...