Příprava nanostrukturovaného TiO2 využitelného pro snižování znečištění životního prostředí

Abstract

This bachelor thesis deals with preparation of nanostructured TiO2 from titanyl sulphate and by subcritical water processing, characterization of TiO2 structural and textural properties and investigation of photocatalytic activity in photo-oxidation of azo-dye Acid Orange 7. TiO2 was prepared from colloid solution of titanyl sulphate by using two methods, hydrothermal and nuclei method, and by subcritical water processing at different temperatures (25-200°C) and pressures (10-30 MPa). The effect of different particle-size of precursor, temperature and pressure of subcritical water on TiO2 crystallization was studied. TiO2 structural properties were characterized by Raman spectroscopy, textural properties such as the specific surface area and the pore volume were determined by nitrogen physisorption. UV-vis spectrometry was used for evaluation of photodegradation tests. It was revealed that different particle-size of precursor processed by subcritical water does not affect TiO2 crystal structure and crystallite-size. Contrary to pressure, the temperature of subcritical water plays the key role in TiO2 crystallization. While TiO2 anatase crystallizes by subcritical water processing of hydrothermally-prepared precursor, by processing of nuclei-prepared precursor Na/H titanate is formed up to 100°C at 10 MPa and TiO2 anatase crystallizes at higher temperature of 200°C at 10 a 30 MPa. TiO2 anatase from hydrothermally-prepared precursor shows significantly higher specific surface area and photocatalytic activity than TiO2 anatase from nuclei-prepared precursor. Na/H titanate does not show any photocatalytic activity.