Effects of oxygen and weak magnetic field on Fe^sup 0^/bisulfite system: performance and mechanisms

The performance and mechanisms of 4-nitrophenol (4-NP) degradation by the Fe0/bisulfite system were systematically investigated for the first time. The evidences presented in this study verified that O2 was a crucial factor that affected the mechanism of Fe0/bisulfite-driven 4-NP degradation. In the...

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Bibliographic Details
Published in:Environmental science and pollution research international 2016-08, Vol.23 (16), p.16761
Main Authors: Xiong, Xinmei, Gan, Jinhong, Zhan, Wei, Sun, Bo
Format: Article
Language:English
Subjects:
Acids
Anoxic conditions
Bisulfite
Degradation
Environmental science
Experiments
Free radicals
Iron
Laboratories
Magnetic fields
Mineralization
Oxidants
Oxidation
Oxidizing agents
p-Nitrophenol
Particle size
Pollutants
Radicals
Studies
Sulfur
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Summary:The performance and mechanisms of 4-nitrophenol (4-NP) degradation by the Fe0/bisulfite system were systematically investigated for the first time. The evidences presented in this study verified that O2 was a crucial factor that affected the mechanism of Fe0/bisulfite-driven 4-NP degradation. In the Fe0/bisulfite/O2 system, Fe0 acted as a supplier of Fe2+ to catalyze bisulfite oxidation that induced a chain reaction to produce reactive radicals for 4-NP degradation. While under N2 purging condition, bisulfite worked as a specified reductant that facilitated the transformation of Fe3+ to nascent Fe2+ ions, which principally accounted for the reductive removal of 4-NP. The application of a weak magnetic field (WMF) efficiently improved the removal rate of 4-NP and did not alter the mechanisms in both Fe0/bisulfite/O2 and Fe0/bisulfite/N2 processes. The secondary radicals, HO·, SO4 ·-, and SO5 ·-, were considered as the most possible active oxidants contributing to the oxidative removal of 4-NP and even partial mineralization under an oxic condition. Compared with anoxic conditions, the performance removal of 4-NP by the WMF-Fe0/bisulfite/O2 system showed less pHini dependence. To facilitate the application of WMF-Fe0/bisulfite/O2 technology in real practice, premagnetization of Fe0 was employed to combine with bisulfite/O2 and proved to be an effective and applicable method for 4-NP removal.
ISSN:0944-1344
1614-7499
DOI:10.1007/s11356-016-6672-7