Photocatalytic degradation of quinoline in aqueous TiO2 suspension

Anatase TiO(2) 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 (λ=365 nm). The influence of reaction parameters such as TiO(2) dosage, initial quinoline concentration and pH was investigated. Under the optimized reaction condition, 91.5% photodegradation efficiency of quinoline was achieved. When the TiO(2) 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(2)) predominantly attacked the pyridine ring of quinoline leading to the formation of 2-aminobenzaldehyde, 2-quinolinone, 4-quinolinone; while the hydroxyl radical (OH) contributed much less by attacking benzene rings resulting in the formation of 5-hydroxyquinoline. The photocatalytic performance of the as-synthesized TiO(2) nanoparticles was comparable to the commercial P25. A tentative mechanism was postulated for the photodegradation of quinoline over TiO(2) nanoparticles.