Sonochemical degradation of methyl orange in the presence of Bi2WO6: Effect of operating parameters and the generated reactive oxygen species.

The Bi 2 WO 6 was prepared by the hydrothermal method and its sonocatalytic activity was studied in the degradation of methyl orange (MO) solutions. The effects of catalytic activity of Bi 2 WO 6 on dye were inspected by the change in absorbance of dye with UV–vis spectrometer. The influences of operational parameters such as the addition amount of Bi 2 WO 6 , pH, the initial concentration of dyes, ultrasonic power and irradiation time on the degradation ratio were investigated. In addition, the obtained results indicated that the kinetics of sonochemical reactions of MO were consistent with the pseudo first-order kinetics and Bi 2 WO 6 had excellent reusability and stability during the sonochemical degradation processes. The generation and kinds of reactive oxygen species (ROS) and their influence on the sonochemical degradation of MO were determined by the methods of oxidation–extraction spectrophotometry and ROS scavengers. The results indicate that the degradation of MO in the presence of Bi 2 WO 6 under ultrasonic irradiation is related to the generation of ROS, in which both singlet molecular oxygen ( 1 O 2 ) and hydroxyl radical ( OH) play important roles in the sonochemical degradation of MO. These experimental results provide a sound foundation for the further development of Bi 2 WO 6 as a sonocatalyst in wastewater treatment. [ABSTRACT FROM AUTHOR]