Enhanced photocatalytic degradation of phenol by immobilized TiO2/dye-loaded chitosan

In this study, an immobilized TiO2/dye-loaded chitosan was designed in a layer-by-layer arrangement for the enhanced photocatalytic degradation of phenol under a 45-W compact household fluorescent light irradiation. The immobilized photocatalyst was supported on glass plates and consists of a porous top layer of TiO2 and sub-layer of chitosan (CS) with chemisorbed Reactive Red 4 (RR4) dye (TiO2/RR4-CS/glass). Results from the optical studies demonstrated that the absorption threshold of the immobilized photocatalyst was shifted to the visible light region with lower recombination of electron-hole pairs. The TiO2/RR4-CS/glass exhibits improved photocatalytic degradation and mineralization of phenol as compared with the TiO2/glass and TiO2/CS/glass photocatalysts, with a degradation rate of 0.030 min(-1) and total mineralization of 76.7%. The immobilized photocatalyst also exhibited excellent photocatalytic stability and could be reused for up to five cycles of phenol treatment. The enhanced photocatalytic performance of the TiO2/RR4-CS/glass can be ascribed to the synergistic photocatalytic and sensitization effects that run concurrently under light irradiation.