Molecular Oxygen Activation with Nano Zero-valent Iron for Aerobic Degradation of Organic Contaminants and the Performance Enhancement

作者：Mu Yi; Jia Falong; Ai Zhihui^*; Zhang Lizhi^*

来源：Acta Chimica Sinica, 2017, 75(6): 538-543.

DOI：10.6023/A17020047

• nano zero-valent iron
• molecular oxygen activation
• reactive oxygen species
• advanced oxidation technology

Nano zero-valent iron (nZVI) is a special kind of iron with large specific surface area, strong reduction activity, and the environmental friendliness. nZVI was usually used to reductively degrade organic pollutants, but its long-term performance was poor and the organic pollutants could not be mineralized. Nano zero-valent iron can reductively activate molecular oxygen to generate reactive oxygen species for oxidation or even mineralization of organic pollutants. Recently, we found the core-shell structure dependent aerobic degradation of organic pollutants by nZVI and proposed a new physical insight into the molecular oxygen activation mechanism of the aerobic nZVI process, where the outward electrons transfer from the iron core initiate the two-electron molecular oxygen activation and surface bound ferrous ions on iron oxide shell favor the single-electron molecular oxygen activation. Several strategies have also been proposed to enhance the production of reactive oxidants by nZVI-induced oxygen activation. We confirmed that addition of extra ferrous ions into the nZVI/O-2 system could generate more surface bound ferrous ions for significantly enhancing the generation of reactive oxygen species. Meanwhile, the introduction of some inorganic or organic ligands in the aerobic nZVI system could also improve the active oxygen species generation efficiency. Finally main typical environmental factors including of the pH value, coexisting ions, natural organic matter on the organic pollutants degradation with the aerobic nZVI were discussed. By the way, we also investigated the anoxic Cr(VI) removal with nZVI. It was found the Cr(VI) removal rate constant was mainly attributed to the reduction of Cr(VI) by the surface bound Fe(II) besides the reduction of Cr(VI) adsorbed on the iron oxide shell via the electrons transferred from the iron core. We also demonstrated that the presence of oxygen molecule can inhibit Cr(VI) removal with nZVI, which was attributed to that the oxygen molecular activation could compete with Cr(VI) for the consumption of surface bond Fe(II) and donor electrons transferred from Fe-0 core.

• 出版日期2017-6-15
• 单位华中师范大学