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KMID : 1024520170260070859
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Journal of the Environmental Sciences
2017 Volume.26 No. 7 p.859 ~ p.868
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Reduction Characteristics of Triclosan using Zero-valent Iron and Modified Zero-valent Iron
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Choi Jeong-Hak
Kim Young-Hun
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Abstract
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In this study, the reductive dechlorination of triclosan using zero-valent iron (ZVI, Fe0) and modified zero-valent iron (i.e.,
acid-washed iron (Aw/Fe) and palladium-coated iron (Pd/Fe)) was experimentally investigated, and the reduction characteristics were evaluated by analyzing the reaction kinetics. Triclosan could be reductively decomposed using zero-valent iron. The degradation rates of triclosan were about 50% and 67% when Fe0 and Aw/Fe were used as reductants, respectively, after 8 h of reaction. For the Pd/Fe system, the degradation rate was about 57% after 1 h of reaction. Thus, Pd/Fe exhibited remarkable performance in the reductive degradation of triclosan. Several dechlorinated intermediates were predicted by GC-MS spectrum, and 2-phenoxyphenol was detected as the by-product of the decomposition reaction of triclosan, indicating that reductive dechlorination occurred continuously. As the reaction proceeded, the pH of the solution increased steadily; the pH increase for the Pd/Fe system was smaller than that for the Fe0 and Aw/Fe system. Further, zero-order, first-order, and second-order kinetic models were used to analyze the reaction kinetics. The first-order kinetic model was found to be the best with good correlation for the Fe0 and Aw/Fe system. However, for the Pd/Fe system, the experimental data were evaluated to be well fitted to the second-order kinetic model. The reaction rate constants (k) were in the order of Pd/Fe > Aw/Fe > Fe0, with the rate constant of Pd/Fe being much higher than that of the other two reductants.
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KEYWORD
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Triclosan, Zero-valent iron (ZVI), Modified ZVI, Reductive dechlorination, Reaction rate constant
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