The Effect of Reactive Red 4 Dye as a Sensitizer in Enhancing Photocatalytic Activity of TiO<sub>2 </sub>for Degradation of Methyl Orange

Abstract

In this work, anionic RR4 dye was used to sensitize TiO2/PVA and TiO2/PEG immobilized system in enhancing photocatalytic degradation of anionic methyl orange (MO) 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 55-W fluorescent lamp and visible light irradiation. The photocatalytic degradation of MO was significantly enhanced for both RR4 dye sensitized Im/TiO2/PVA and Im/TiO2/PEG with first order rate constant was ca. 0.080 min-1 and 0.071 min-1 respectively under 55-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 MO dye by producing hydroxyl radical.