Ultrasound enhanced heterogeneous activation of peroxydisulfate by magnetite catalyst for the degradation of tetracycline in water

The removal of tetracycline by magnetite (Fe3O4) activated peroxydisulfate (Na2S2O8) in the presence of ultrasound irradiation has been performed in this study. The effects of Na2S2O8 concentration, Fe3O4 addition, ultrasonic power, initial concentration and initial pH on the degradation of tetracycline were investigated. The results showed that tetracycline removal rate increased with the increase of Fe3O4 dosage, but decreased with the increase of initial pH and initial tetracycline concentration. With the optimum values of Na2S2O8 concentration and ultrasound power, the highest degradation rate can be achieved. The scavenging effect was examined by using ethanol, tert-butyl alcohol and 1,4-benzoquinone to evaluate the roles of sulfate radicals, hydroxyl radicals and superoxide radicals. The results indicated that sulfate radicals and the hydroxyl radicals played important roles in the degradation of tetracycline by Fe3O4/Na2S2O8/US process. (C) 2011 Published by Elsevier B.V.