Kinetics and mechanism of enhanced norfloxacin degradation by Fe3O4@La-BiFeO3 based on weak magnetization and efficient charge separation

Improving the yield of reactive oxygen species and inhibiting the recombination of photogenerated e - and h + have been reliable strategies to accelerate the rate-limiting step for nano photocatalytic materials. A novel magnetic Fe 3 O 4 @La-BiFeO 3 composite with variable molar ratios was successfully synthesized via a facile hydrothermal method for the photo-Fenton-like degradation of norfloxacin (NOR) under visible light irradiation. The comprehensive characterization of the crystal phase purity, morphological structure and elemental composition of the catalyst confirmed the formation of a heterojunction structure between Fe 3 O 4 and La-BiFeO 3 . The effects of the composite molar ratio, initial pH, catalyst addition, and H 2 O 2 concentration on the degradation efficiency were investigated. 20% Fe 3 O 4 @La-BiFeO 3 showed the best catalytic activity with 93.8% removal of NOR after 60 min of reaction and the pseudo-first-order rate constant was 0.05952 min −1 , attributed to the synergistic interaction of the photocatalytic and Fenton-like processes. The excellent stability and recyclability of the catalyst ensured the catalytic reactions continued to occur efficiently. The appropriate amount of Fe 3 O 4 reduced the band gap of the catalyst, and the introduction of a weak magnetic field accelerated the transfer of electrons between interfaces, effectively restrained the recombination of photogenerated e - /h + and directly enhanced the yield of ·OH and O 2 · - . This work not only realized the preparation of a heterogeneous photo-Fenton-like catalyst with high application potential for the degradation of antibiotics, but also provided new prospects for designing efficient catalysts on the basis of theoretical guidance.