Enhanced catalytic performance of Cu-doped MnFe2O4 magnetic ferrites: Tetracycline hydrochloride attacked by superoxide radicals efficiently in a strong alkaline environment

It is important to develop a catalyst that can maintain good activity in alkaline environment for Fenton or Fenton-like reactions. In order to achieve stable Fenton catalytic degradation in a wide pH range, this study reports Cu-doped MnFe 2 O 4 heterogeneous catalysts still has excellent effect when the pH is extended to 11 for removing organic pollutants, such as tetracycline hydrochloride (TC-HCl). The synergistic effect among Fe, Mn and Cu ions has been proved to enhanced the catalytic activity in this work. When the molar ratio of Cu/Mn = 4:1, the porous Cu 0·8 Mn 0·2 Fe 2 O 4 materials had the highest photo-Fenton catalytic activity compared with pure MnFe 2 O 4 , CuFe 2 O 4 and other Cu x Mn 1-x Fe 2 O 4 . The XPS showed that Cu 0·8 Mn 0·2 Fe 2 O 4 formed oxygen vacancies, which exposed more active sites to attract more H 2 O 2 for TC-HCl degradation. Results indicated 94.3% of TC-HCl was efficiently degraded by 0.1 g/L Cu 0·8 Mn 0·2 Fe 2 O 4 with 50 mM H 2 O 2 at pH = 11 under 30 min visible light irradiation, and the corresponding apparent rate constant was 0.08286 min −1 . With free radicals quenching experiment, O 2 − was responsible for the high catalytic degradation and OH was participated in the photo-Fenton reaction. To sum up, Cu 0·8 Mn 0·2 Fe 2 O 4 exhibited high activity, great stability and easily recyclable, which eliminated the pH limitation of the Fenton reaction and provided practical application performance for water purification .