Enhancement of Fenton processes at initial circumneutral pH for the degradation of norfloxacin with Fe@FeS core–shell nanowires

The disadvantages of narrow working pH range (2.5-4.0), accumulation of iron sludge and incomplete degradation have hindered the practical application of the traditional homogeneous Fenton technique. In this research, Fe@FeS core-shell nanowires were synthesised and the innovative Fe@FeS/Fe²⁺/H₂O₂ system was adopted for norfloxacin (NOR) degradation at an initial circumneutral pH. More than 95% NOR has been removed in the Fe@FeS/Fe²⁺/H₂O₂ system within 30 min at pH 7. After investigating the concentration change of total iron, Fe²⁺ and H₂O₂ during the degradation process, NOR degradation in the Fe@FeS/Fe²⁺/H₂O₂ system might be attributed to the combined effect of homogeneous Fenton reaction and heterogeneous Fenton process. Besides that, the added Fe@FeS has accelerated Fe³⁺/Fe²⁺ redox cycle with extremely high degree. The generated reactive ^●OH has been identified by electron paramagnetic resonance spectrometer results, possible degradation intermediates have also been proposed according to Gas chromatography-mass spectrometry analysis results. Moreover, Fe@FeS core-shell nanowires showed excellent reusability, it is a promising heterogeneous Fenton catalyst that is applicable for practical application.