Titanium dioxide (TiO2) occurs in nature in many polymorphic forms. The best known are anatase and rutile. Crystals of these phases can be prepared by environmentally friendly hydrothermal synthesis of the titanium complex solution. The solution was hydrothermally treated in a batch reactor and industrial autoclaves. This was followed by the characterization and analysis of the obtained products. During the master's thesis, we studied the impact of mixing on our solution and system. Through Kolmogorov theory, we proved that mixing has no effect on our system. We also investigated the influence of different holding times and heating rates on the crystallization process at a temperature of 200 °C. We tried to find out at what temperature the crystallization process starts for our solution. We heated the solutions to different final temperatures and evaluated how this parameter affects the "efficiency" of the crystallization. With the experiments listed above, we wanted to better understand crystallization process of Ti-complex solution under hydrothermal conditions and explain, what effect do certain parameter changes have on the proportion of obtained phases, the size and shape of the crystals, the specific surface area and photoactivity. We used X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectrophotometry to analyze our products.
|
