Abiotic transformation of chlorinated aliphatic ground water contaminants: characterization of mineral reaction products

PI：Elizabeth Butler Proposal编号：CBET-1033836机构：俄克拉荷马大学题目：氯化脂肪族地下水污染物的非生物转化：矿物反应产物的表征环境水污染物，如四氯乙烯(PCE)、三氯乙烯(TCE)和四氯化碳(CT)，由于广泛存在于受污染地点，可能会对美国公民的健康造成不利影响。大量研究表明，含有亚铁和/或硫化物的非生物矿物可以转化这些化合物，有时生成完全无毒的反应产物。矿物介导的非生物转化可用于修复技术，如原位反应区和监测的自然衰减。虽然矿物转化PCE、TCE和CT的有机产物已经得到了很好的表征，但PCE、TCE和CT等污染物氧化矿物时形成的产物还没有得到很好的研究，这是本研究的重点。这项研究的总体目标是确定氯化脂肪族污染物氧化矿物时形成的固相产物的特征，并评估在自然或工程条件下再生活性矿物的潜力。将研究两种矿物(硫化铁(FeS))和氯化物绿锈(GR-Cl，一种混价氧化铁)和三种模型污染物(PCE、TCE和CT)。这项研究的具体目标是：(1)表征PCE、TCE和CT氧化FeS和GR-Cl的速率；(2)确定这些污染物氧化FeS和GR-Cl的矿物相关产物；以及(3)评估在非生物还原剂(对于FeS)和/或细菌(对于FeS和GR-Cl)存在的情况下，是否可以批量和流经系统再生FeS和GR-Cl。批量实验将在火焰密封玻璃瓶中进行，其中含有缺氧的矿物质和污染物。矿物转变的固相产物将通过X射线衍射、X射线光电子能谱和带有X射线分析的扫描电子显微镜进行监测。矿物转化的溶解产物将通过Fe(II)、S(-II)和可还原或可提取的铬(II)的分析来监测。硫磺(Cres)，包括元素硫和多硫化物。批量实验完成后，他们将制备邮票大小的聚甲基丙烯酸甲酯(有机玻璃)包裹矿粉的芯片，并将其放置在流经条件下的土柱中。然后，他们将监测PCE、TCE和CT氧化矿物的固相和溶解产物，以及在细菌存在下活性矿物物种的再生，所有这些都是在流动条件下进行的。有机玻璃载体将使它们能够将活性矿物直接与土壤和细菌接触，以便我们随后提取它们，并监测PCE、TCE和CT氧化后发生的矿物学变化。这里提出的研究将使涉及非生物矿物的修复技术更准确地长期应用，如原位反应区。这将使居住在人口中心的许多美国人受益，这些中心也包含高度集中的地下水污染地点。除了这些直接影响外，还将根据研究结果开发适合本科生和研究生课程的地下水污染物非生物修复教育材料，并提交给NSF K-Gray Engineering Path数字图书馆。这些材料将通过专业组织广泛推广，并将有助于填补当前大学教科书的空白。本科生和研究生将参与这项研究，从而为环境工程教育和实践的职业生涯做准备。研究成果将在研究人员和从业人员参加的科学会议上传播，并将在该领域广泛阅读的期刊上发表。

PI: Elizabeth ButlerProposal Number: CBET-1033836Institution: University of OklahomaTitle: Abiotic transformation of chlorinated aliphatic ground water contaminants: characterization of mineral reaction productsGround water contaminants such as tetrachloroethylene (PCE), trichloroethylene (TCE), and carbon tetrachloride (CT) have the potential to adversely impact the health of U.S. citizens due to their widespread occurrence at contaminated sites. Numerous studies have shown that abiotic minerals containing ferrous iron and/or sulfide can transform these compounds, sometimes to reaction products that are completely nontoxic. Mineral mediated abiotic transformations can be used in remediation technologies such as in situ reactive zones and monitored natural attenuation. While the organic products of PCE, TCE, and CT transformation by minerals have been well characterized, the products that form when the minerals are oxidized by contaminants such as PCE, TCE, and CT have not been well studied and are the focus of this research. The overall objective of the research is to characterize the solid phase products that form upon mineral oxidation by chlorinated aliphatic contaminants, and to assess the potential for regeneration of reactive minerals under natural or engineered conditions. Two minerals (iron sulfide (FeS)) and chloride green rust (GR-Cl, a mixed valence iron oxide) and three model contaminants (PCE, TCE, and CT) will be studied. The specific objectives of the research are to: (1) characterize the rates of FeS and GR-Cl oxidation by PCE, TCE, and CT; (2) identify the mineral-associated products of FeS and GR-Cl oxidation by these contaminants; and (3) assess whether FeS and GR-Cl can be regenerated in the presence of abiotic reductants (for FeS) and/or bacteria (for FeS and GR-Cl) in batch and flow through systems. Batch experiments will be carried out in flame sealed glass ampules containing anoxic slurries of minerals and contaminants. Solid phase products of mineral transformation will be monitored by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy with X-ray analysis. Dissolved products of mineral transformation will be monitored by analysis of Fe(II), S(-II), and chromium (II) reducible or ?extractable? sulfur (CrES), which includes elemental sulfur and polysulfides. After batch experiments are complete, they will prepare postage-stamp-sized chips of poly(methyl methacrylate) (Plexiglass) coated with mineral powders and place them in soil columns under flow through conditions. Then, they will monitor the solid phase and dissolved products of mineral oxidation by PCE, TCE, and CT, and the regeneration of reactive mineral species in the presence of bacteria, all under flow through conditions. The Plexiglass supports will allow them to place the reactive minerals in direct contact with soil and bacteria in such a way that we can subsequently extract them and monitor mineralogical changes that occur upon oxidation by PCE, TCE and CT.The research proposed here will enable more accurate long term application of remediation technologies involving abiotic minerals such as in situ reactive zones. This will benefit the many Americans who live in population centers that also contain high concentrations of sites with ground water contamination. In addition to these direct impacts, educational materials on abiotic remediation of ground water contaminants, suitable for undergraduate and graduate classes, will be developed based on the research results and submitted to the NSF K-Gray Engineering Pathway Digital Library. These materials will be widely promoted through professional organizations, and will help to fill a gap in current college textbooks. Undergraduate and graduate students will participate in this research, thereby preparing for careers in environmental engineering education and practice. Research results will be disseminated at scientific meetings attended by both researchers and practitioners, and will be published in widely read journals in the field.