Water pollution caused by synthetic dyes such as orange G or orange gelb has been increasing during the past few years due to their extensive use in the industrial fields including textile, histology, paper and dye stuff. Hence, their releasing imposes serious dangers to the environment due to theirs toxicity, persistence in the environment, and low biodegradability [1]. One of the most important methods for their efficient degradation is the use of photocatalysts like modified titanium dioxide nanoparticles [2]. In this study, modification of titanium dioxide by carbon was done in the presence of ultrasound and by classical method. Then, their effects was compared in degradation of orang G. The size, structure and band gap of the photocatalyst was determined by XRD, TEM and UV-vis spectrum (with drawing Tauc plot). The results have shown that the sonochemical synthesized photocatalyst had a better effect on the orange G degradation under solar light, in comparison with the conventional method and also unmodified catalyst. The effects of various parameters such as pH and dose of photocatalyst were investigated on the degradation of orange G. Achieving to the maximum optical absorption in the visible range and the increase of the photocatalytic efficiency for the complete removal and mineralization of the orange G under sunlight irradiation are the interesting points of this work.

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