The promoted Fenton degradation of norfloxacin by a S-ZnO modified MnFe2O4 with micro-acidic environment

This study synthesized MnFe 2 O 4 @S-ZnO with varying S-ZnO loading and investigated their catalytic activity towards Fenton degradation of norfloxacin (NOF). The MnFe 2 O 4 @S-ZnO/H 2 O 2 system achieved 98.3 % of NOF removal within 60 min, with the catalytic activity enhanced by 1.8 times compared to MnFe 2 O 4 . XPS results indicated that Mn and Fe are the active catalytic sites. The doping of S elements accelerated the reduction rates of Fe 3+ and Mn 3+ , thereby improving the utilization efficiency of H 2 O 2 and generating more •OH radicals. The Lewis acidic sites on the surface of MnFe 2 O 4 @S-ZnO coordinated with and reduced the concentration of OH − in the suspension, thereby increasing the acidity of theMnFe 2 O 4 catalyst surface, expanding the pH range of the Fenton reaction to alkaline conditions, allowing the composite material to maintain a NOF removal efficiency of over 90.0 % at even high pH (9.0–10.0). The presence of inorganic anions and humic acid (HA) played negative roles on the NOF degradation, but the MnFe 2 O 4 @S-ZnO/H 2 O 2 system can still achieve a minimum NOF degradation of 62.8 % within 60 min. Moreover, the MnFe 2 O 4 @S-ZnO catalyst exhibited relatively high stability and possessed easy recoverability. Furthermore, this catalyst overcomes the pH limitations of the traditional Fenton reaction, demonstrating significant advantages and promising application prospects.