Quinone類化合物是一種普遍存在自然環境中的電子傳遞物質，有助於電子從還原劑上轉移至諸如四氯化碳等氯化碳氫化合物以加速其在還原態環境中的降解。在本研究中，針對五種quinone類化合物於硫環境下對四氯化碳的還原脫氯反應進行探討，結果顯示添加quinone類化合物能加速還原脫氯的反應速率達2至40倍，且反應速率的增加與使用的quinone類化合物具有相當的依存性，由快至慢依次為NQ > BQ >> AQDS > MQ ~ LQ。進一步分析各quinone化合物於硫化氫環境中的光譜變化，可推論quinone類化合物會因化學結構的不同而產生不同的活性物質以利電子的傳遞；對BQ及NQ而言，在與硫化氫共存時會因加成反應而生成反應性強的硫化quinone化合物。而AQDS則具有極低的氧化還原電位，會在硫化氫環境中生成quinone自由基型態而加速氯化有機物的還原降解反應。LQ及MQ則會在相同環境下生成還原態quinone化合物。另外，研究也發現pH值會大幅影響quinone類化合物對於還原脫氯反應的速率。有鑑於自然環境中腐植質含有許多的quinone官能基，因此本研究中亦選用兩種腐植酸探討其quinone官能基與還原脫氯反應的關聯性，在添加腐植酸的實驗中，四氯化碳的分解效率可提升1.6至2.4倍，配合光譜分析的結果，推論這兩種腐植酸皆是以還原態quinone化合物作為活性電子傳遞物質。

The dechlorination of carbon tetrachloride (CT) in homogeneous aqueous solutions containing quinone compounds as electron mediators and thiol compounds as bulk reductants was investigated. The use of thiol compounds including sodium hydrosulfide and cysteine as bulk reductant can effectively dechlorinate CT. The dechlorination of CT followed pseudo first-order kinetics and the pseudo first-order rate constant (kobs) was 0.051 d-1 with 5 mM NaHs and 0.009 d-1 with cysteine. Addition of quinone compounds including AQDS, benzoquinone (BQ), naphthoquinone (NQ), lawsone (LQ) and menadione (MQ) could significantly increase the rate and efficiency of CT dechlorination. The enhanced effect followed the order of NQ > BQ >> AQDS > MQ~LQ. A 2- to 40-fold increase in kobs relative to the solutions in the absence of quinone compounds was observed. Spectroscopic results including EPR, FTIR, UV-Vis and LC-MS showed that the selected quinone compounds can form various active electron mediators for electron transfer and can be categorized into three groups. The first group included BQ and NQ that could produce mercaptoquinone as active redox mediators. The second one included AQDS and the quinone moiety can be reduced to semiquinones. Moreover, lawsone and menadione can be reduced to hydroquinone by thiol compound to slightly enhance the dechlorination efficiency of CT. Environmental factors such as pH value, concentrations of thiol and quinone compounds can significantly influence the dechlorination efficiency and the rate of CT and exhibited positive correlations between the kobs for CT dechlorination and environmental factors. Moreover, two humic acids, Aldrich and Yang-ming mountain humic acid were shown to be reduced to hydroquinone moieties as active electron mediators by hydrosulfide ion and the kobs for CT dechlorination were 1.6 – 2.4 times higher than that without humic acid. Since humic substances contain large quinone moiety and sulfur compounds and are abundant under anaerobic conditions, results obtained in this study indicate the potentials of utilizing humic substances for effective electron mediators.

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