Degradation of metronidazole in aqueous solution by nano-ZnO/UV photocatalytic process

Abstract

In this study, the effects of some operational factors, such as pH value, nano-ZnO loading, UV-A irradiation time, and power of radiation on the degradation efficiency of metronidazole (MNZ) in aqueous solution were discussed through photocatalytic experiments using nano-ZnO as the photocatalyst. Results show that removal of metronidazole (MNZ) and COD has a direct correlation with power of UV-A lamp and irradiation time. MNZ solution (80 mg L⁻¹) was rapidly removed by the irradiation of UV lamp OSRAM 125 W high pressure within 180 min. In nano-ZnO/UV photocatalysis reactor, irradiation time and power of UV lamp have a great effect on metronidazole degradation. Statistical analysis (One-way ANOVA) has shown that the pH (in acedic and basic condition) and variation of nano-ZnO concentration has no significant effects on MNZ removal, COD, and BOD₅/COD ratio. But the maximum degradation of MNZ occurred at pH 10 and 1.5 gL⁻¹ nano-ZnO. Maximum degradation of MNZ and COD was 96.55 and 95.42%, respectively. In addition, biodegradability improved from ∼0 to 0.091 within 180 min.

Keywords:

• Photocatalysis
• Metronidazole
• Nano-ZnO/UV

Acknowledgment

The authors would like to thank Mr. Bonyani for working with an HPLC instrument in the laboratory of nutrition group.