Photocatalytic activities of TiO2 layers immobilized on glass substrates by dip-coating technique toward the decolorization of methyl orange as a model organic pollutant

The aim of this article is to evaluate the photocatalytic activities of the immobilized catalyst layers of titanium dioxide for the decolorization of methyl orange aqueous solution (MO) as a model organic contaminant under UV irradiation. Three stable layers of TiO2 powder were coated on glass substrate by facile dip-coating technique. XRD analysis showed anatase crystalline structure of catalyst films. The films crystallinity increased with the layers number. SEM analysis showed porous TiO2 films. The multi-coating increased the coverage surface of glass support. The catalyst films showed well reproducibility and good adhesion to the support after tests. The effects of operating parameters and the number of catalyst layers on the MO decolorization were investigated. The kinetic study of the MO photodecolorization showed a pseudo-first-order reaction. The MO color removal by the use of three coated layers of catalyst in the optimum reactor was more effective and 5 times faster than that with the use of one coated layer of catalyst at normal conditions. The immobilized layers of TiO2 powder was found photocatalytic active for complete MO decolorization in the optimum reactor. The immobilized system may replace suspension mode and eliminate the costly separation process.