Sono-enhanced degradation of dye pollutants with the use of H2O2 activated by Fe3O4 magnetic nanoparticles as peroxidase mimetic

Sono-enhanced degradation of a dye pollutant Rhodamine B (RhB) was investigated by using H2O2 as a green oxidant and Fe3O4 magnetic nanoparticles (MNPs) as a peroxidase mimetic. It was found that Fe3O4 MNPs could catalyze the break of H2O2 to remove RhB in a wide pH range from 3.0 to 9.0 and its peroxidase-like activity was significantly enhanced by the ultrasound irradiation. At pH 5.0 and temperature 55 °C, the ultrasound-assisted H2O2–Fe3O4 catalysis removed about 95% of RhB (0.02 mmol L−1) in 15 min with a apparent rate constant of 0.15 min−1 for the degradation of RhB, being 6.5 and 37.6 folds of that in the simple catalytic H2O2–Fe3O4 system, and the simple ultrasonic US-H2O2 systems, respectively. The beneficial synergistic behavior between Fe3O4 catalysis and ultrasonic was demonstrated to be dependent on Fe3O4 dosage, H2O2 concentration, pH value and temperature. As a tentative explanation, the observed significant synergistic effects was attributed to the positive interaction between cavitation effect accelerating the catalytic breakdown of H2O2 over Fe3O4 nanoparticles, and the function of Fe3O4 MNPs providing more nucleation sites for the cavitation inception.