Synergistic Effect In TiO₂ Photocatalytic Degradation

Photocatalytic degradation of organic contaminant is a promising technology of wastewater treatment. In this field, nano-sized TiO2 is used as photocatalyst extensively for its high photoactivity and good stability. When the TiO2-water system is irradiated under UV-light, it will produce ·OH radicals and super-oxide ions O2-.The application of this property to treat organic pollutants in water was noticed by many researchers in this field.However, many problems such as the recombination of electron-hole consist in the course of degradation leading to low quantum efficiencies of titanium dioxide. In recent years, much work in relation to the promotion of photoactivity has been done. And synergistic effect of titanium dioxide has attracted much attention because it can restrain the recombination of electron-hole and improved quantum efficiencies.This dissertation mainly concerns to the synergistic effect of titanium dioxide and other material. Various samples were studied such as model wastewater (phenol solution, gentian violet), real wastewater (low-concentration wastewater, high-concentration wastewater). The main works and achievements are described as follows:As a model wastewater, phenol solution was photodegraded on condition that inorganic oxidizing species H2O2 and K2S2O8 were added. The change of apparent rate constant, phenol concentration and TOC value proved the presence and function of synergistic effect.The mixture of titanium dioxide and diatomite or activated carbon had synergistic effect in suspend systems. In this experiment, gentian violet was targeted and the difference of systems was discussed.In photocatalytic reactor equipped with TiO2 fixed film, the feasibility and synergism of the addition of different oxidants ClO2 and H2O2 were studied in course of photocatalytic degradation of pharmaceutical wastewater.The effective degradation of mixed pesticides wastewater was achieved by the synergism of UV/TiO2 and Fenton agent. This advanced oxidation process was studied in a photo-catalytic reactor (v=6L).