In this study, photocatalytic degradation of azo dye Direct Red 23(DR23) in aqueous solution using TiO2/Ag2O nano particles was employed to the degradation rate of dye enhances. Using of sol-gel method for synthesis nano particles TiO2/Ag2O. Nano particles have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area analysis and Fourier transform infrared spectroscopy (FT-IR). A circulating fludized bed photo reactor (CFBR) with capacity 3 L, and equipped with a lamp UV-C (15 W) was used. The effect of operational parameters such as: pH, catalyst amount, dye concentration and H2O2 concentration were studied. The results showed that pH= 6, catalyst amount = 25 (mg/lit), dye concentration= 30 ppm and H2O2 concentration = 30 ppm was optimum conditions for this reaction. A first order reaction with k= 0.0678 min−1 was observed for the photocatalytic degradation reaction. The COD measurement results indicated that all organic substances were completely mineralized.
