Photocatalytic degradation of quinoline in aqueous TiO2 suspension

Anatase TiO2 nanoparticles with an average size of 16 nm were synthesized via a modified sol-gel method and were employed to degrade quinoline under UV irradiation (lambda = 365 nm). The influence of reaction parameters such as TiO2 dosage, initial quinoline concentration and pH was investigated. Under the optimized reaction condition, 91.5% photodegradation efficiency of quinoline was achieved. When the TiO2 nanoparticles were reused for four times, the photodegradation efficiency was still as high as 90.6%. The analysis of the organic intermediates suggested that superoxide radical (O-center dot(2)) predominantly attacked the pyridine ring of quinoline leading to the formation of 2-aminobenzaldehyde, 2-quinolinone, 4-quinolinone: while the hydroxyl radical ((OH)-O-center dot) contributed much less by attacking benzene rings resulting in the formation of 5-hydroxyquinoline. The photocatalytic performance of the as-synthesized TiO2 nanoparticles was comparable to the commercial P25. A tentative mechanism was postulated for the photodegradation of quinoline over TiO2 nanoparticles. 2012 Elsevier B.V. All rights reserved.