期刊
CHEMOSPHERE
卷 168, 期 -, 页码 1457-1466出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2016.11.138
关键词
MnO2; Active phase; 4-Nitrophenol; Catalytic ozonation; Average oxidation state
资金
- National Science Fund for Distinguished Young Scholars [51425405]
- National Natural Science Foundation of China [21207133]
- Major Science and Technology Program for Water Pollution Control and Treatment [2015ZX07202-013]
Catalytic ozonation is a highly effective method in wastewater treatment, and MnO2 materials are widely recognized as active heterogeneous catalysts in this process. Many works reported the progress in active MnO2 synthesis, but the active phase is rarely systematically studied. In this paper, all six phases of MnO2 (alpha-, beta-, delta-, gamma-, lambda- and epsilon-) were synthesized by facile methods. Their catalytic activities in ozonation of 4-nitrophenol (4-NP) were evaluated and correlated with the physicochemical properties obtained from Xray Diffraction (XRD), transmission electron microscopy (TEM), physical adsorption and cyclic voltam-metry (CV) analysis. alpha-MnO2 was found to be the most active catalyst in 4-NP degradation at neutral pH. MnO2 with low average oxidation state (AOS) showed stronger oxidation/reduction peaks in CV characterization, which benefited catalytic decomposition of ozone to generate active species. Superoxide radical was confirmed as the main oxidizing species, along with singlet oxygen and ozone molecule oxidation in bulk solution and little contribution of oxidation on the MnO2 surface. Mn2+ leaching happened during catalytic ozonation, but its catalytic role is negligible. This result may give rise to the preparation of new active MnO2 catalysts. (C) 2016 Elsevier Ltd. All rights reserved.
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