Photocatalytic Degradation of Textile Dye Effluent Using Catalyst TiO2/Doped TiO2

Abstract

Textile dyes (reactive black 5) are examples of water contaminants that are difficult to degrade by physicochemical and/or biological methods in water. Photocatalytic oxidation process has been examined to degrade reactive black 5 dye, in this work. Undoped and Fe3+ doped TiO2 have been examined for such purposes. UV light with undoped TiO2 and visible light with doped TiO2 can be used for degradation of reactive black 5 dye, giving CO2 and H2O as final products. Visible light was successfully used to degrade reactive black 5 using Fe-TiO2. It was noticed that the degradation was also depend on catalyst dose, initial concentration of contaminants and pH of dye solution. Recovered and reused TiO2 catalyst showed lower activity than fresh ones. The activity loss is due to adsorption of dye on catalyst surface.

TiO2 doped with Fe3+, designated as Fe-TiO2 was prepared via wetness impregnation method. The resulting products were characterized by X-ray diffraction, scanning electron microscopy, and UV-vis absorption. Experimental results revealed that when dye degraded uder UV light using undoped TiO2, the optimum parameters were pH = 6, TiO2 = 1 gl-1 and initial dye concentration = 100 ppm. Reaction rate constant was found to be 0.0127 min-1, for the first order reaction kinetics. Results were showed that the catalyst was active 95% of the dye after the first cycle degraded and it is reduces to 63 % after sixth cycle of dye degradation.

The results from this work showed that doping with metal ions could turn the inert amorphous TiO2 to become photocatalytically active under visible light. The doping was done for three concentrations of Fe3+ (2 %, 4% and 6% by weight). Results showed that the degradation increase as the amount of Fe3+ increase in dopant. This indicates the importance of doped and undoped TiO2 catalyst in dye degradation processes.