Effect of crystalline structure on terbuthylazine degradation by H2O2-assisted TiO2 photocatalysis under visible irradiation

Various methods for shifting the optical response of TiO_2 into the visible(Vis) range have been reported. Herein, we reported the application of a TiO_2/H_2O_2/Vis process and the effects of TiO_2 crystalline structure on the degradation of terbuthylazine. The results indicated that TiO_2 crystalline structure and H_2O_2 addition had significant effects on terbuthylazine degradation: its degradation rate could be increased from 7% to 70% with H_2O_2 addition after 180 min of reaction, the synergistic degradation of terbuthylazine by TiO_(2-)Fe~(3+) was substantially accelerated, with the degradation rate reaching up to 100% after20 min of reaction, and rutile TiO_2 showed better photocatalytic activity and a more obvious synergistic effect than anatase TiO_2. The addition of free-radical scavengers(tert-butyl alcohol or methanol) inhibited the degradation efficiency of rutile TiO_2, but had a relatively minor effect on anatase TiO_2. Fluorescence spectrophotometry analysis indicated that hydroxyl free radicals could be continuously produced when using rutile TiO_2 as the photocatalyst. Degradation of terbuthylazine catalyzed by rutile TiO_2 occurred mainly in solution, but occurred on the particle surface of the photocatalyst when catalyzed by anatase TiO_2. This study provides new insight into the role of TiO_2 crystalline structure on the degradation of terbuthylazine and its photocatalytic degradation mechanism.