Degradation of acid green B by low-frequency ultrasoundsynergized with Fe-Ni-Mn/Al2O3

Key words: 
• low-frequency ultrasound /
• degradation /
• acid green B /
• catalyst

Abstract: The degradation of azo dye acid green B in aqueous solution was studied by low-frequency ultrasound in the presence of catalyst Fe-Ni-Mn/Al2O3. The effects of initial concentration and pH value of dyestuff solution, catalyst, saturated gas and H2O2 on degradation of acid green B were investigated. The results show that catalyst Fe-Ni-Mn/Al2O3 is favorable for degradation of acid green B and there exist synergetic effects in Fe-Ni-Mn/Al2O3 catalyst combined with lowfrequency ultrasonic irradiation. The optimal dosage of catalyst Fe-Ni-Mn/Al2O3 is 6 g/L. The degradation rate of acid green B is highly dependent on pH value and acidic condition helps to promote the degradation of acid green B. The optimum degradation rate of acid green B can be achieved when pH value is 3.8. However, the degradation rate decreases with the increase of dye initial concentration and optimal concentration is 100 mg/L. Moreover, degradation rate of acid green B is enhanced significantly in the presence of saturated gases used in this study. The favorable effects on degradation of acid green are listed in the following decreasing order: mixed gas (air+argon)＞oxygen＞argon. Dosage of H2O2 to the reaction system is proved to be beneficial to the degradation of acid green B. 91.4% of colourity removal rate of acid green B can be achieved under the optimal experimental conditions.