Efficient degradation of paracetamol with nanoscaled magnetic CoFe2O4 and MnFe2O4 as a heterogeneous catalyst of peroxymonosulfate

Typical spinel ferrites of CoFe2O4 and MnFe2O4 were studied as heterogeneous catalysts of peroxymonosulfate (PMS) for the degradation of paracetamol (APAP) in water. The APAP degradation followed a pseudo-first-order kinetics pattern (R2 > 0.95) under conditions tested. In the presence of 0.2 g/L catalyst, APAP with initial concentration of 10 mg/L would be 90.5% and 100% removed in CoFe2O4/PMS and MnFe2O4/PMS system, respectively. Higher catalyst dosage, higher PMS dosage, neutral pH and lower concentration of HA favored APAP degradation in each system. After being recycled for three times, MnFe2O4 and CoFe2O4 could still effectively catalyze PMS to react with APAP, with the removal efficiencies of 100% and 76.1%, respectively. The production of sulfate radical and hydroxyl radical was validated from the scavenging tests, results showed that sulfate radical was the main reactive species responsible for APAP degradation. Plausible mechanisms on the activation processes were proposed based on the radical identification tests and XPS analysis, showing that Mn2+-Mn3+/Fe3+-Fe2+ recycle and Co2+-Co3+/Fe3+-Fe2+ recycle on catalyst were responsible for the radical generation. The results demonstrated that both CoFe2O4 and MnFe2O4 MNPs activated PMS were promising technologies for water pollution caused by pharmaceuticals.