Iron dependent oxidative remediation of chloethylenes

氯化乙烯是超级基金场地地下水中一类常见的环境污染物，已成为清洁技术应用的目标。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“泵送治疗”策略或微生物依赖性修复的有效且经济的替代方案。原则上，氯化乙烯可以有效地脱氯为无毒的碳质产物和无机氯化物，依次应用还原和氧化脱氯化学。随着由特定零价铁填充的可渗透反应处理壁的引入，含氯有机物的原位还原处理已取得相当大的进展。还原处理最适合氯乙烯类的高度氯化成员，目前需要氧化处理（空气喷射）的支持来降解氯化程度较低的氯有机物和非氯化石油烃。本提案研究了一种新颖的氧化方法，该方法依赖于氯乙烯的催化氧化/脱氯，由特定的铁试剂在牺牲量的双氧和还原剂（通常是金属铁或锌）或单独的过氧化氢存在下介导。这项工作的具体目标是（i）开发铁基氧化系统，通过在活化双氧或过氧化氢过程中检查相关铁配合物和中间体的基本化学，以在水介质中进行氧化脱氯或氯乙烯，以解开攻击氯乙烯的活性氧化剂； (ii) 通过检查所涉及的活性氧化剂的性质，通过中间体的光谱研究和动力学分析，并探索该氧化剂添加到氯乙烯的方式（协同、逐步（自由基、碳阳离子）），提供对脱氯过程的机械理解； (iii) 探索铁试剂的异质化形式，与零价铁一起在柱脱氯研究中进行测试。

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.