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KMID : 1024520140230050903
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Journal of the Environmental Sciences
2014 Volume.23 No. 5 p.903 ~ p.910
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Treatment Characteristics of Trichloroethylene(TCE) by Oxidation and Reduction with Nanoscale Zero-valent Iron
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Park Young-Bae
Jung Yong-Jun
Choi Jeong-Hak
Moon Byung-Hyun
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Abstract
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This study examined the treatment characteristics of hard-to-degrade pollutants such as TCE which are found in organic
solvent and cleaning wastewater by nZVI that have excellent oxidation and reduction characteristics. In addition, this study
tried to find out the degradation characteristics of TCE by Fenton-like process, in which H2O2 is dosed additionally.
In this study, different ratios of nZVI and H2O2, such as 1.0 mM : 0.5 mM, 1.0 mM : 1.0 mM, and 1.0 mM : 2.0 mM were
used. When 1.0 mM of nZVI was dosed with 1.0 mM of H2O2, the removal efficiency of TOC was the highest and the first
order rate constant was also the highest. When 1mM of nZVI was dosed with 0.5 mM of H2O2, the first order rate constant
and removal efficiency were the lowest. The size of first order rate constant and removal efficiency was in the order of nZVI1.0 mM : H2O2 1.0 mM ＞ nZVI 1.0 mM : H2O2 2.0 mM ＞ nZVI 1.0 mM : H2O2 0.5 mM ＞ H2O2 1.0 mM ＞ nZVI 1.0 mM. It is estimated that when 1.0 mM of nZVI is dosed with 1.0 mM of H2O2, Fe2+ ion generated by nZVI and H2O2 react in the stoichiometric molar ratio of 1:1, thus the first order rate constant and removal efficiency are the highest. And when 1.0 mM ofnZVI is dosed with 2.0 mM of H2O2, excessive H2O2 work as a scavenger of OH radicals and excessive H2O2 reduce Fe3+ into Fe2+.As for the removal efficiency of TOC in TCE by simultaneous dose and sequential dose of nZVI and H2O2, sequential dose showed higher first order reaction rate and removal efficiency than simultaneous dose. It is estimated that when nZVI is dosed 30 minutes in advance, pre-treatment occurs and nanoscale Fe0 is oxidized to Fe2+ and TCE is pre-reduced and becomes easier to degrade. When H2O2 is dosed at this time, OH radicals are generated and degrade TCE actively.
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KEYWORD
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nZVI(Nano-sized zero-valent iron), TCE, Fenton oxidation
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