Corrinoid-Mediated Reduction of Tetrachloroethene, Trichloroethene, and Trichlorofluoroethene in Homogeneous Aqueous Solution: Reaction Kinetics and Reaction Mechanisms

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• 作者：Guy Glod ; Werner Angst ; Christof Holliger ; and René ; P. Schwarzenbach
• 刊名：Environmental Science & Technology
• 出版年：1997
• 出版时间：January 1997
• 年：1997
• 卷：31
• 期：1
• 页码：253 - 260
• 全文大小：368K
• 年卷期：v.31,no.1(January 1997)
• ISSN：1520-5851

文摘

It is shown that in homogeneous aqueous solution containingtitanium(III) citrate or titanium(III)-NTA as bulkelectrondonor, cobalamin, cobinamide, and cobamide are effectiveelectron transfer mediators for the reduction of tetrachloroethene (PCE), trichloroethene (TCE), andtrichlorofluoroethene (TCFE). For a given chlorinatedethene,the reaction rate varied only slightly with pH and typeof corrinoid present and was about 5 and 50 times fasterfor PCE as compared to TCFE and TCE, respectively.Evidence is presented that the first and rate-limitingstepof the reduction of PCE, TCE, and TCFE by super-reducedcorrinoids is a dissociative one-electron transfer yieldingthecorresponding vinyl radicals. Furthermore, theeliminationof a chloride radical from the 1,1-dichlorovinyl radicalyielding chloroacetylene and subsequently acetylene isproposed to account for the direct formation of acetyleneout of TCE. Finally, it is demonstrated that athigherreduction potentials the corrinoid mediators may beblockedby the formation of additionproducts.