Solar photocatalytic decolorization of two azo dye derivatives, acid red 17 and reactive red 241 in aqueous suspension

The photocatalytic decolorization approach using sunlight has potential applications in the treatment of effluents from textile dye industries. With this aim, the decolorization of two representative commercially used textile azo dye derivatives such as AR17 and RR241 have been investigated under sunlight and atmospheric oxygen in aqueous suspension of titanium dioxide by monitoring the change in concentration using UV-Vis. Spectrophotometry. A detailed decolorization kinetics of both dye derivatives have been investigated under variety of conditions such as type of TiO₂ powders (Anatase/Anatase-rutile mixture), catalyst dose, substrate concentration, pH and electron acceptors (H₂O₂ and KBrO₃). The highest decolorization rate for dye derivative AR17 and RR241 were observed at pH 7.5 and 6.0, respectively. The photocatalyst Degussa P25 having 80:20 anatase:rutile mixture was found to be better for the decolorization of both the dyes as compared to two other hotocatalysts tested. The decolorization rate was enhanced in the presence of electron acceptors such as H₂O₂ and KBrO₃. Results demonstrated that the decolorization of dyes under sunlight is strongly influenced by different parameters investigated in this paper.