title: Effects of oxygen and weak magnetic field on Fe(0)/bisulfite system: performance and mechanisms.
abstract: The performance and mechanisms of 4-nitrophenol (4-NP) degradation by the Fe(0)/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 Fe(0)/bisulfite-driven 4-NP degradation. In the Fe(0)/bisulfite/O2 system, Fe(0) acted as a supplier of Fe(2+) 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 Fe(3+) to nascent Fe(2+) 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 Fe(0)/bisulfite/O2 and Fe(0)/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-Fe(0)/bisulfite/O2 system showed less pHini dependence. To facilitate the application of WMF-Fe(0)/bisulfite/O2 technology in real practice, premagnetization of Fe(0) was employed to combine with bisulfite/O2 and proved to be an effective and applicable method for 4-NP removal.
authors.affiliation: Department of Civil Engineering and Urban Construction, Jiujiang University, Jiujiang, 332005, Jiangxi, People's Republic of China. xiongxinmei1981@163.com.
authors.forename: Xinmei
authors.initials: X
authors.lastname: Xiong
authors.affiliation: Department of Civil Engineering and Urban Construction, Jiujiang University, Jiujiang, 332005, Jiangxi, People's Republic of China.
authors.forename: Jinhong
authors.initials: J
authors.lastname: Gan
authors.affiliation: Department of Civil Engineering and Urban Construction, Jiujiang University, Jiujiang, 332005, Jiangxi, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhan
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Sun
mesh_terms: D004785:Environmental Pollutants / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D060526:Magnetic Fields; D008956:Models, Chemical; D009596:Nitrophenols / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D013447:Sulfites / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D009596:Nitrophenols; D013447:Sulfites; D007501:Iron; C042345:hydrogen sulfite; D010100:Oxygen; C024836:4-nitrophenol
keywords: Bisulfite; Free radical; Oxidation; Premagnetization; Reduction; Weak magnetic field