| The degradation of norfloxacin in aquatic environment was studied in the presence of Fe3O4 nanoparticles and H2O2.The effects of solution pH, temperature, dose of catalysts and concentration of H2O2 on norfloxacin degradation were surveyed. The degradation behaviors of different substrates by nano-Fe3O4/H2O2 were investigated and the reaction mechanism of norfloxacin was discussed. The results showed that the reaction was strongly pH-dependent and favored in acidic solution (pH=3.5). The removal efficiency of norfloxacin was enhanced with the increase of temperature, catalysts dosage and H2O2 concentration. The degradation efficiency of norfloxacin by nano-Fe3O4/H2O2 was significantly higher than those of sulfathiazole, phenolic and aniline compounds. In the presence of 4.4 mmol·L-1 of H2O2, 0.80 g·L-1 of Fe3O4 and T=303 K, norfloxacin was degraded completely in 5 min. The F element in norfloxacin molecule existed totally as F- in solution within 5 min, and the removal efficiency of total organic carbon was 57% in 1 h. In the ESR spectrum of nano-Fe3O4/H2O2 system, the characteristic peaks of BMPO-·OH adduct was detected, however, the intensity of the peaks was reduced to 5% with the addition of tert-butanol, a strong ·OH scavenger, and the degradation efficiency of norfloxacin was correspondingly decreased to 10% in 1 h. These results indicated that ·OH played an important role on norfloxacin degradation, and the reaction proceeded based on a heterogeneous Fenton-like system. |
