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.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 실험 재료
  2.2. 실험 방법
 3. 결과 및 고찰
  3.1. Fe0, Aw/Fe 및 Pd/Fe를 이용한 triclosan의 제거
  3.2. Triclosan 제거반응에 따른 pH 변화
  3.3. Triclosan 분해반응 중간생성물
  3.4. Triclosan 제거반응의 반응속도 모델 및 속도상수
 4. 결 론
 REFERENCES

• 최정학(부산가톨릭대학교 환경공학과) | Jeong-Hak Choi (Department of Environmental Engineering, Catholic University of Pusan)
• 김영훈(안동대학교 환경공학과) | Young-Hun Kim (Department of Environmental Engineering, Andong National University) Corresponding author