Photodegradation of phenol by UV/TiO2 and Vis/N,C-TiO2 processes: Comparative mechanistic and kinetic studies

摘要

Photodegradation pathway was compared for two systems: N,C-doped TiO2 under visible light and P-25 under UV irradiation. Degradation efficiency of phenol, phenol intermediates and ~·OH radicals formation was investigated for both systems. The obtained results showed similar efficiency of phenol degradation for doped TiO2 excited by visible light to P-25 irradiated by UV light. 60 min irradiation in the Vis/N,C-TiO2 and UV/P-25 systems resulted in 69 and 76% of phenol degradation, respectively. However, photoactivity under visible light (λ>400nm) of N,C-TiO2 was four times higher than photoactivity of P-25 TiO2. Presented data indicated different degradation pathways of pollutants in the presence of nonmetal-doped TiO2 and visible light than in UV/TiO2 system. The HPLC-MS analysis revealed the lack of hydroxyl-by-products after irradiation of phenol in the presence of N,C-TiO2 and visible light, whilst they were found in P-25/UV system. Although the degradation of organic contaminants was efficient, no generation of hydroxyl radical in the N,C-doped TiO2/Vis system was observed.