Hollow Meso-crystalline Mn-doped Fe3O4 Fenton-like catalysis for ciprofloxacin degradation: Applications in water purification on wide pH range

Herein, an unprecedented heterogeneous Fenton-like catalyst with a hollow meso-crystalline Fe3O4 catalyst doped with Mn was prepared for the first time through a one-pot method, which can effectively activate H2O2 in a wide pH range and has good stability. The results show the catalyst can achieve rapid degradation of ciprofloxacin (CIP) under the conditions of pH = 4.5 to pH = 9.5, which greatly expands the application conditions of Fenton. Sufficient experimental exploration clearly demonstrated that the uniform doping of Mn in Fe3O4 crystal lattice, and the formation process of Mn-doped Fe3O4 hollow meso-crystalline microspheres was reasonably analyzed based on Ostwald curing theory and bubble theory. The dual reaction center theory reasonably explains the reaction mechanism of the catalyst. The H2O2 adsorbed on the electron-rich Fe center is reduced to •OH, while the H2O2 adsorbed on the electron-deficient Mn center is oxidized to •O2–/HO2•, •OH and •O2–/HO2• are further converted to 1O2, which participates in involved in the degradation process of CIP. This research provides new ideas for the rational design of catalysts that can apply the heterogeneous Fenton reaction to actual water purification in a wide pH range.