Visible light-activated N-doped TiO<sub>2</sub> nanoparticles for the photocatalytic degradation of microcystin-LR

Abstract

N-Doped nano-crystalline TiO2 powder have been by the sol-gel method. The characteristics of TiO2 were carried out using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-visible reflection spectrum. The result showed that the band gap was narrower, and there are obviously absorption in visible light region. Under the visble light (λ > 420 nm), this catalyst has been used to degrade MC-LR. The concentration of MC-LR was detected by high performance liquid chromatography, the structure elucidation of reactionin termediates was accomplished by LC-MS/MS. At last, the mineralization effect was detected by total organic carbon (TOC) tester. Simultaneously, photocatalytic oxidation species was tracked by electron spin resonance (ESR) and Peroxidase method. Fourteen hours later, the degradation rate reached 100% and the mineralized rate of MC-LR was 78% after 20 h. And the major oxidation species in the system was hydroxyl radical (·OH) and H2O2. We found 13 reactionin termediates in the system. Four parts MC-LR are easy to be attacked and oxidized. Some peptide bonds break down too with longer reaction time.