| Abstrakt: |
Degradation of a dye by 1-D nano-sized β-MnO2 particles was investigated to understand the mechanisms involved. Batch experiments were performed in a system of β-MnO2, hydrogen peroxide (H2O2), methylene blue (MB), and radical scavengers. The prepared β-MnO2 had a 1-dimensional nano-sized structure and showed a negative zeta potential at pH higher than 3.7. In the presence of H2O2, MB was rapidly degraded by β-MnO2. The rate of MB degradation was not significantly inhibited by the initial pH values from 6.05 to 10.02, but notably decreased at pH 3.04, at which point the β-MnO2 particles dissolved. The effect mechanisms of operational parameters (i.e., H2O2, catalyst dose) in β-MnO2/MB/H2O2 system were investigated. The removal rate of MB was remarkably reduced in the existence of p-quinone and was even more affected when sodium azide was added, indicating that the singlet oxygen radical (1O2) plays an important role. The obtained results point out that MB degradation by nano-sized β-MnO2 is due to the catalytic oxidation of H2O2 on β-MnO2surface reactive sites, rather than surface oxidation or adsorption. The reusability of nano-sized β-MnO2 was also examined after five times of recycling to evaluate the applicability of β-MnO2 for wastewater treatment. [ABSTRACT FROM AUTHOR] |
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