CAREER: Formation and Reactivity of Nanoscale Corrosion Products - An Integrated Research and Education Plan

职业：纳米级腐蚀产物的形成和反应性 - 综合研究和教育计划

• 批准号: 0348125
• 负责人: Peter Vikesland
• 金额: $ 40万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0348125&HistoricalAwards=false
• 关键词: CAREER; Formation; Reactivity; Nanoscale; Corrosion

0348125VikeslandThe career development plan has been broken down into two primary components: a research plan describing experiments to examine the formation and reactivity of nanoscale corrosion products and a teaching plan that is designed to reinvigorate the pedagogical environment of the Introduction to Environmental Engineering class at Virginia Tech.The objective of this project is to evaluate the role that nanoscale corrosion products play in determining the reactivity of the granular iron based treatment schemes used for the remediation of organohalide contaminated subsurface environments. The results from the proposed studies will be used in the development of an improved conceptual model of the phenomena responsible for contaminant remediation within granular iron systems. Using Iron Corrosion to Remediate Contaminated GroundwaterThe discovery that chlorinated solvents readily react with reduced iron has led to rapid acceptance of in situ iron Permeable Reactive Barriers (PRBs) as the cleanup method of choice for many contaminated sites. Although the exact mechanisms involved have not been fully elucidated, field demonstrations indicate that the reactions can be rapid under environmentally relevant conditions. At the current time, over eighty field-scale PRBs employing iron as a reactive material for treatment of contaminated groundwater have been installed. Questions remain, however, concerning the relative reactivities of the numerous types of iron used in these walls. A key variable that dictates the applicability of iron PRBs as a remediation technique is the organohalide degradation rate. These rates are a function not only of the identity and concentration of the organohalide undergoing remediation (i.e., chlorinated alkanes vs. chlorinated alkenes, but also of the groundwater composition (i.e., pH, ionic content), the quantity of iron present, and its structural makeup. The quantity, or concentration, of iron is important because contaminant reduction requires either direct electron-transfer between the contaminant and the iron surface or indirect electron-transfer via surface evolved reactive intermediates (e.g., H2). Observed reaction rates, as evinced by pseudo-first-order rate coefficients (kobs values), typically scale linearly with iron concentration, a result indicative of surface mediated reactions. The type or composition of the iron metal used for organohalide remediation also significantly affects iron reactivity. Observed differences in the reactivity of various types of iron were historically attributed primarily to variability in their surface areas. Recent reports have suggested, but never experimentally documented, that this additional variability results from fundamental differences in the composition of the iron substrates.

0348125Vikesland职业发展计划分为两个主要组成部分：一个研究计划描述了检查纳米级腐蚀产物的形成和反应性的实验，另一个教学计划旨在重振弗吉尼亚理工大学环境工程概论课程的教学环境。该项目的目的是评估纳米级腐蚀产物在确定颗粒铁基处理的反应性中所起的作用 用于修复有机卤化物污染的地下环境的计划。拟议研究的结果将用于开发改进的概念模型，该模型负责颗粒铁系统内污染物修复的现象。利用铁腐蚀来修复受污染的地下水氯化溶剂很容易与还原铁发生反应，这使得人们迅速接受原位铁渗透性反应屏障（PRB）作为许多污染场地的首选清理方法。 尽管所涉及的确切机制尚未完全阐明，但现场演示表明，在环境相关条件下，反应可以快速进行。 目前，已经安装了 80 多个现场规模的 PRB，使用铁作为反应材料来处理受污染的地下水。 然而，关于这些墙壁中使用的多种铁的相对反应性的问题仍然存在。 决定铁 PRB 作为修复技术的适用性的一个关键变量是有机卤化物降解率。 这些速率不仅取决于正在修复的有机卤化物的特性和浓度（即氯化烷烃与氯化烯烃），还取决于地下水组成（即 pH、离子含量）、存在的铁量及其结构组成。铁的数量或浓度很重要，因为污染物减少需要污染物之间的直接电子转移 以及铁表面或通过表面演化的反应中间体（例如H2）进行间接电子转移。 观察到的反应速率，如伪一级速率系数（kobs 值）所示，通常与铁浓度成线性比例，这一结果表明表面介导的反应。用于有机卤化物修复的铁金属的类型或组成也显着影响铁的反应性。观察到的差异 历史上，各种铁的反应性主要归因于其表面积的变化。最近的报告表明，但从未经过实验记录，这种额外的变异性是由铁底物成分的根本差异造成的。