In this study, a new method has developed for the synthesis of TiO2–Cu2O nano-composite with high optical absorption in the visible range and high photocatalytic activity in mineralization of sodium dodecyl- benzenesulfonate (SDBS) in an ultrasonic bath with low intensity at 40 kHz. The results of EDAX, TEM and XRD confirmed the purity, crystallinity and the structure of the nanocomposite particles with the size less than 10 nm. Ultrasound played a key role in the formation of nanocomposite with highest photocatalytic activity in mineralization of SDBS under sunlight. The degradation of SDBS by sunlight irradiation showed that the extent of mineralization depends on the operating conditions. In addition, the TiO2–Cu2O that contained 5% (mole ratio) TiO2 exhibited better photocatalytic activity than either Cu2O or TiO2 alone or other composites with different mole ratios. So that, the mineralization percentage of SDBS in the solution reached to 100% after 90 min and the mineralization on the surface of the catalyst was completed after 240 min. The data obtained from the degradation experiments fit the first-order kinetics and the adsorption obeyed the Langmuir model.

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