Enhancement of Fenton processes at initial circumneutral pH for the degradation of norfloxacin with Fe@Fe2O3 core-shell nanomaterials

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.

Insights into the role of nanoscale zero-valent iron in Fenton oxidation and its application in naphthalene degradation from water and slurry systems

Few researches have focused on the role of nanoscale zero-valent iron (nZVI) in Fenton-like process for polycyclic aromatic hydrocarbons (PAHs) removal. In this study, the naphthalene (NAP) degradation tests in ultrapure water showed that nZVI addition could enhance NAP degradation from 79.7% to 99.0% in hydrogen peroxide (H2O2)/Fe (II)/nZVI/NAP system at the molar ratio of 10/5/3/1, showing the excellent role of nZVI in promoting NAP removal. Multiple linear regression analysis found that the correlation coefficient between H2O2 consumption and NAP degradation was converted from -9.17 to 0.48 with nZVI and 1-mM H2O2, indicating that nZVI could decompose H2O2 more beneficially for NAP degradation. Multiple Fe (II)-dosing and iron leaching tests revealed that nZVI could gently liberate Fe (II) and promote Fe (II)/Fe (III) redox cycle to enhance the NAP degradation. When the H2O2/Fe (II)/nZVI/NAP molar ratios of 10/5/3/1 and 50/25/15/1 were applied in the simulated NAP contaminated actual groundwater and soil slurry, respectively, 75.0% and 82.9% of NAP removals were achieved. Based on the major degradation intermediates detected by GC/MS, such as 1,4-naphthalenedione, cinnamaldehyde, and o-phthalaldehyde, three possible NAP degradation pathways were proposed. This study provided the applicable potential of nZVI in Fenton process for PAHs contaminated groundwater and soil remediation. PRACTITIONER POINTS: nZVI enhanced the NAP degradation in Fenton-like process. Three schemes of NAP degradation pathway were proposed. nZVI performed well in the remediation of the simulated NAP contamination.

UV-assisted nitrogen-doped reduced graphene oxide/Fe3O4 composite activated peroxodisulfate degradation of norfloxacin

We reported the preparation of NGO-Fe₃O₄ by simple hydrothermal-co-precipitation. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). It was demonstrated that norfloxacin (NOR) could be effectively degraded by the UV/NGO-Fe₃O₄/PDS system. The degradation efficiency reached 100% within 13 min (the concentration of NOR and S2O82- were 100 mg L^-1 and 1 mM, respectively; m(NGO-Fe₃O₄): m(PDS) = 4: 1; pH: 3.0). In addition, NGO-Fe₃O₄ showed stable catalytic activity in recycling. The analysis found that the in-situ generated ·OH was the main active free radicals but SO4-⋅ also participated in the NOR degradation. Based on the identified intermediates, the NOR degradation pathways were proposed with UV/NGO-Fe₃O₄/PDS system.

Activation of Na2S2O8 by α-Fe2O3/CuS composite oxides for the degradation of Orange II under visible light irradiation

Layered α-Fe2O3/CuS nanoflowers with abundant active sites were synthesized by a hydrothermal method.

Degradation of orange II by Fe@Fe2O3 core shell nanomaterials assisted by NaHSO3

Fe@Fe₂O₃ core shell nanomaterials with different Fe₂O₃ shell thickness were synthesized and the Fe@Fe₂O₃/NaHSO₃ Fenton-like system was used for the decomposition of Orange II. The consequences are compared with traditional Fenton Fe@Fe₂O₃/H₂O₂ system. The Fe@Fe₂O₃/NaHSO₃ system showed extremely good applicability under both strongly acidic and alkaline conditions. The new Fe@Fe₂O₃-(2)/NaHSO₃ system led to more than 99% degradation in 30 s when the pH was 3, which indicated that the Fe@Fe₂O₃ material was not corroded during the process even under strongly acidic condition. The above Fe@Fe₂O₃-(2) material was prepared from nano-zero-valent iron aged in solution for 2 h to synthesize the Fe₂O₃ shell. The reaction mechanism of Fe@Fe₂O₃/NaHSO₃ Fenton-like system was also concluded. The oxidation efficiency was highly improved due to rapid electron transfer between Fe core and Fe₂O₃ shell, which promoted the direct recycling of ≡Fe³⁺ and ≡Fe²⁺ and thus accelerated the generation of SO₄^- and OH radicals.