A Study On Doping Nanometer Titania And Its Degradation Performance

For several decades, titanium dioxide has been studied as a hopeful photocatalyst among various semiconductors because of the application of solar energy conversion, air purification, and organic contaminant photodegradation. Unfortunately, because of its large band gap of3.2eV, it can be activated only under UV light irradiation of wavelength<387nm. UV light constitutes only a small fraction (5%) of the solar spectrum, so any improvement of the photocatalytic efficiency of TiO2by changing its optical response to the visible range will have a long-term positive effect.The thesis was focused on the compounding of doped and co-doped titanium dioxide and their photocatalytic performance. New photocatalytic materials were prepared by doping nonmetallic elements and metal elements and the photocatalytic performance was studied by decomposite simulated dye wastewater of Methyl orange and Rhodamine B in sun light.Catalyst such as visible-light response of C-doped titanium dioxide, Zn,C-co-doped titanium dioxide, Sulfur-doped titanium dioxide and Zr,S-co-doped titanium dioxide were all compounded by Sol-Gel method and Mechanochemical method,and we try to study the influences of calcine temperature and doping amounts. The results showed that calcine temperature and doping amounts have a significant effect on the degradation rate. TiO2doping with different substance has different optimal calcine temperature, for example, optimal calcine temperature of AC-doped titanium dioxide is300℃, while optimal calcine temperature of C3H6N6-doped titanium dioxide is700℃; Too much or less doping amounts is unfavorable of photo degradation, for example, the optimal doping amounts of AC is6wt.%with calcine temperature of500℃,on which the decomposition rate of methyl orange is69%with the reaction time of5h in sun light.the result is higher than AC-doping amounts of4wt.%and8wt.%.The effect of pH, initial concentration and TiO2dosage were also studied in this paper. The results showed that photo decomposition rate of methyl orange reduce gradually with the increase of initial concentration; Methyl orange is more likely to decomposite in acidic conditions, and the optimal pH is3. TiO2dosage has a optimal value,and it’s not the more the better. When the dosage of Zn-C-TiO2was2.0g/L, the initial concentration of methyl orange was10mg/L and pH=3, the decomposition rate of5h was nearly100%in sun light.Muti-factor photocatalytic kinetic model was established under the conditions of different initial concentration, pH and TiO2dosage.