Magnetic manganese ferrite spinel decorated with CeO₂ （MnFe₂O₄@CeO₂） for activation of peracetic acid to degrade tetracycline in water

Heterogeneous catalysts have shown great potential in the activation of peracetic acid （PAA） for the degradation of antibiotics in water. Taking tetracycline in water as the object， this study prepared magnetic MnFe2O4@CeO2 composite materials via a one-step low-temperature co-precipitation method， and characterized them using SEM， BET， VSM， FT-IR， and XPS. The effects of Mn/Ce molar ratio， PAA concentration， catalyst dosage， initial pH， co-existing anions， and humic acid concentration on catalytic degradation efficiency of tetracycline （TC） by the MnFe2O4@CeO2/PAA system were investigated. The results indicated that at an initial TC concentration of 10 mg/L， a Ce/Mn molar ratio of 1∶3， pH of 7， and PAA concentration of 200 μmol/L， with a MnFe2O4@CeO2 dosage of 0.1 g/L， the system could degrade 97.3% of TC within 30 minutes. MnFe2O4@CeO2 exhibited a good degradation effect on TC within a pH range of 3 to 9. Anions and humic acid had varying degrees of inhibitory effects on the degradation efficiency of the MnFe2O4@CeO2/PAA system. Electron paramagnetic resonance （EPR）， quenching experiments， and XPS analysis collectively revealed the degradation mechanism of TC by the MnFe2O4@CeO2/PAA system， where Mn and Ce are the key elements to activating PAA. CH3C（O）OO•， •OH， and 1O2 were the main reactive species involved in TC degradation， with CH3C（O）OO• playing a primary role. Additionally， the MnFe2O4@CeO2/PAA system was tested for its broad applicability in different real water bodies and against other refractory organic pollutants. Finally， the stability and reusability of the MnFe2O4@CeO2 composite materials were assessed. The magnetic MnFe2O4 loaded with CeO2 reduced the leaching of metal ions and exhibited good stability. After five cycles of reuse， the TC removal rate of the MnFe2O4@CeO2/PAA system remained at 86.9%.