Iron dependent oxidative remediation of chloethylenes

氯代乙烯是超级基金所在地地下水中的一类常见环境污染物，已成为清理技术应用的目标。在不同的治疗方法中，依赖于氧化还原过程的原位抗生素修复有望成为“泵和治疗”策略或微生物依赖修复的一种有效和经济的替代方法。从原理上讲，氯化乙烯可以有效地脱氯成无毒的碳化物和无机氯化物，依次应用红外还原和氧化脱氯化学。随着渗透性反应处理墙的引入，氯有机物的原位还原处理已经有了相当大的进步，处理壁由特别的零价铁填充。还原处理最适合氯乙烯类中氯化程度较高的成员，目前需要通过氧化处理(空气喷射)来支持，以降解较少的氯化有机化合物和非氯化石油碳氢化合物。本提案研究了一种新的氧化方法，该方法依赖于氯乙烯的催化氧化/脱氯，在牺牲了一定量的氧气和还原剂(通常是金属铁或锌)或单独存在过氧化氢的情况下，由特定的铁试剂介导。这项工作的具体目标是：(I)开发基于铁的氧化系统，以执行水介质中的氧化脱氯或氯乙烯，通过研究在激活氧气或过氧化氢的过程中相关铁络合物和中间体的基本化学，以分解攻击氯乙烯的活性氧化剂；(Ii)通过对中间体的光谱研究和动力学分析，通过检查所涉及的活性氧化剂的性质，并通过探索这种氧化剂加入氯乙烯的方式(协调的，逐步的(自由基，碳阳离子))，提供对脱氯过程的机械理解；以及(3)探索将在柱脱氯研究中与零价铁一起测试的铁试剂的异质性版本。

Chlorinated ethylenes constitute a class of common environmental contaminants of groundwater at superfund sites that have been targeted fro application of cleanup technologies. Among different treatment methodologies, in situ antibiotic remediation that relies upon redox processes holds promise as an effective and economical alterative to "pump-and-treat" strategies or microbial-dependent remediation. In principle, chlorinated ethylenes can be efficiently dechlorinated to innocuous carbonaceous products and inorganic chloride, ir reductive and oxidative dechlorination chemistry is applied in sequence. In situ reductive treatment of chloroorganics has been considerably advanced with the introduction of permeable reactive treatment walls filled by particular zero-valiant iron. The reductive treatment is best suited for the highly-chlorinated members of the chloroethylene class and currently requires support by oxidative treatment (air sparging) to degrade less chlorinated chloroorganics and non-chlorinated petroleum hydrocarbons. The present proposal investigates a novel oxidative approach that relies upon catalytic oxygenation/dechlorination of chloroethylenes, mediated by specific iron regents in the presence of sacrificial amounts of dioxygen and a reducing agent (usually metallic Fe or Zn) or hydrogen peroxide alone. The specific targets of this work are to (i) develop iron-based oxidizing systems to perform oxidative dechlorination or chloroethylenes in aqueous media, by examining the fundamental chemistry of relevant iron complexes and intermediates in the course of activating dioxygen or hydrogen peroxide to unravel an active oxidant that attacks chloroethylenes; (ii) provide mechanistic understanding of the dechlorination process, by examining the nature of the active oxidant involved, via spectroscopic investigation of intermediates and kinetic analysis, and by exploring the manner by which this oxidant adds to chloroethylenes (concerted, step-wise (radical, carbocationic)); and (iii) explore heterogenized versions of the iron reagents to be tested in column dechlorination studies in conjunction with zero-valent iron.