Degradation of phenol in water by the combination of sonolysis and photocatalysis

Abstract

The combination of sonolysis and photocatalysis has been used to degrade an aqueous solution of phenol. The synergistic index for sonophotocatalysis was 1.06, indicating that there was a slightly synergistic effect between sonolysis and photocatalysis, and that the degradation by sonolysis, photocatalysis, and sonophotocatalysis presented a good fit to the pseudo-first-order kinetic model. Additionally, the effects of parameters such as the initial pH value of the solution, dissolved gases, salt addition, Fe³⁺ ions, and metaloxide (CuO and MnO₂) on the sonophotocatalytic degradation were studied. The results shown that acidic/weakly acidic condition is superior to alkaline condition, and higher concentration of dissolved oxygen and the presence of Fe³⁺ favored the phenol degradation, CuO and MnO₂ had no significant effect on the degradation, while NaHCO₃ restrained the degradation rate.

Keywords:

• Sonolysis
• Sonophotocatalysis
• Photocatalysis
• Phenol

Acknowledgement

This study was financially supported by the National Nature Science Foundation of China (Nos. 51078148 and 20277011).