Enhanced humic acid degradation by Fe3O4/ultrasound-activated peroxymonosulfate : Synergy index, non-radical effect and mechanism

In this study, Fe3O4/ultrasound (US) activated-peroxymonosulfate (PMS) was employed to degrade humic acid (HA). Magnetic nano-scale Fe3O4 particles were prepared via a co-precipitation method. The physical and chemical properties of Fe3O4 were characterized explicitly by a variety of methods, including scanning electron microscope-energy dispersive spectrometer (SEM-EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), Zeta potential, Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), and vibrating-sample-magnetometer (VSM). The synergy index of US and Fe3O4 activated PMS for humic acid degradation was calculated. After 20 min of reaction under the Fe3O4/Ultrasound/PMS system, 10 mg/L of HA solution was completely degraded. Batch experiments were conducted to determine the effect of PMS concentration, HA concentration, dosage of Fe3O4, and pH value on the degradation of HA in the absence and presence of US. The thermal and non-thermal effects of US on HA degradation were studied. Electron paramagnetic resonance (EPR) and quenching tests indicated that non-radical singlet oxygen (O-1(2)) is the dominant contributor for HA degradation. This study provides a fast and cost-effective method for HA removal.

Automated summary

Fe3O4/ultrasound activated-peroxymonosulfate was used to degrade humic acid, with batch experiments revealing the effects of PMS concentration, HA concentration, Fe3O4 dosage, and pH value on HA degradation; the study found that non-radical singlet oxygen is the dominant contributor to HA degradation.