A Study on RR4 Dye as a Sensitizer in Enhancing Photoactivity of Immobilized Photocatalysts

Abstract

In this work, anionic RR4 dye was used to sensitize TiO2/PVA and TiO2/PEG immobilized system in enhancing photocatalytic degradation of cationic methylene blue (MB) dye. 0.3g of TiO2 and polymer binder was coated onto a clean glass plate by using brush technique to develop optimum immobilize TiO2 system. A comparison study between immobilized TiO2/PVA (Im/TiO2/PVA) and Immobilized TiO2/PEG (Im/TiO2/PEG) system with and without RR4 sensitizer were carried out under 45 W fluorescent lamp and visible light irradiation. The photocatalytic degradation of MB was significantly enhanced for both RR4 dye sensitized Im/TiO2/PVA and Im/TiO2/PEG with 1st order rate constant was ca. 0.035 and 0.030 min-1 respectively under 45-W fluorescent lamp. Same observation as well under visible light irradiation whereby enhanced of those RR4 sensitized immobilized photocatalysts were recorded as compared with immobilized photocatalysts without RR4 as sensitizer. The photocatalytic enhancement under Im/TiO2/PVA/RR4 and Im/TiO2/PEG/RR4 are due to the ability of RR4 dye to become electron (e-) donor for conduction band (CB) of TiO2, thus making TiO2 CB riches with electron, eventually this e- is used to remove MB by producing hydroxyl radical.