Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-Dong, Yuseong-Gu, Daejeon 305-701, Republic of Korea.
Chemosphere. 2011 Feb;82(8):1103-8. doi: 10.1016/j.chemosphere.2010.12.002. Epub 2010 Dec 24.
Selective redox degradation of chlorinated aliphatics by Fenton reaction in pyrite suspension was investigated in a closed system. Carbon tetrachloride (CT) was used as a representative target of perchlorinated alkanes and trichloroethylene (TCE) was used as one of highly chlorinated alkenes. Degradation of CT in Fenton reaction was significantly enhanced by pyrite used as an iron source instead of soluble Fe. Pyrite Fenton showed 93% of CT removal in 140 min, while Fenton reaction with soluble Fe(II) showed 52% and that with Fe(III) 15%. Addition of 2-propanol to the pyrite Fenton system significantly inhibited degradation of TCE (99% to 44% of TCE removal), while degradation of CT was slightly improved by the 2-propanol addition (80-91% of CT removal). The result suggests that, unlike oxidative degradation of TCE by hydroxyl radical in pyrite Fenton system, an oxidation by the hydroxyl radical is not a main degradation mechanism for the degradation of CT in pyrite Fenton system but a reductive dechlorination by superoxide can rather be the one for the CT degradation. The degradation kinetics of CT in the pyrite Fenton system was decelerated (0.13-0.03 min(-1)), as initial suspension pH decreased from 3 to 2. The formation of superoxide during the CT degradation in the pyrite Fenton system was observed by electron spin resonance spectroscopy. The formation at initial pH 3 was greater than that at initial pH 2, which supported that superoxide was a main reductant for degradation of CT in the pyrite Fenton system.
在封闭体系中，研究了黄铁矿悬浮液中芬顿反应对氯化脂肪族化合物的选择性氧化还原降解。四氯化碳（CT）被用作全氯烷烃的代表性目标，三氯乙烯（TCE）被用作高氯烯烃的代表之一。与使用可溶性 Fe 相比，使用黄铁矿作为铁源可显著增强芬顿反应中 CT 的降解。黄铁矿芬顿反应在 140 分钟内可去除 93%的 CT，而使用可溶性 Fe(II)的芬顿反应去除率为 52%，使用 Fe(III)的芬顿反应去除率为 15%。向黄铁矿芬顿体系中添加 2-丙醇可显著抑制 TCE 的降解（TCE 的去除率从 99%降至 44%），而 2-丙醇的添加略微改善了 CT 的降解（CT 的去除率为 80-91%）。结果表明，与黄铁矿芬顿体系中羟基自由基对 TCE 的氧化降解不同，羟基自由基不是 CT 在黄铁矿芬顿体系中降解的主要氧化机制，而是超氧自由基的还原脱氯可能是 CT 降解的主要机制。在黄铁矿芬顿体系中，随着初始悬浮液 pH 值从 3 降至 2，CT 的降解动力学减慢（0.13-0.03 min(-1)）。通过电子顺磁共振波谱观察到 CT 在黄铁矿芬顿体系中的降解过程中超氧自由基的形成。在初始 pH 3 时的形成量大于在初始 pH 2 时的形成量，这支持了超氧自由基是黄铁矿芬顿体系中 CT 降解的主要还原剂。
