Institute of Environmental Health, Oregon Health & Science University, 20000 NW Walker Road, Beaverton, Oregon 97006, United States.
Environ Sci Technol. 2013 Feb 5;47(3):1573-80. doi: 10.1021/es304564q. Epub 2013 Jan 23.
The fate of nano zerovalent iron (nZVI) during subsurface injection was examined using carboxymethylcellulose (CMC) stabilized nZVI in a very large three-dimensional physical model aquifer with detailed monitoring using multiple, complementary detection methods. A fluorescein tracer test in the aquifer plus laboratory column data suggested that the very-aggressive flow conditions necessary to achieve 2.5 m of nZVI transport could be obtained using a hydraulically constrained flow path between injection and extraction wells. However, total unoxidized nZVI was transported only about 1 m and <2% of the injected nZVI concentration reached that distance. The experimental data also indicated that groundwater flow changed during injection, likely due to hydrogen bubble formation, which diverted the nZVI away from the targeted flow path. The leading edge of the iron plume became fully oxidized during transport. However, within the plume, oxidation of nZVI decreased in a fashion consistent with progressive depletion of aquifer "reductant demand". To directly quantify the extent of nZVI transport, a spectrophotometric method was developed, and the results indicated that deployment of unoxidized nZVI for groundwater remediation will likely be difficult.
采用羧甲基纤维素（CMC）稳定的纳米零价铁（nZVI），在一个具有详细监测的非常大的三维物理模型含水层中，考察了 nZVI 在地下注入过程中的命运，使用了多种互补的检测方法。在含水层中的荧光素示踪剂测试以及实验室柱数据表明，可以通过在注入井和提取井之间采用水力约束流道来获得实现 2.5 m nZVI 运移所需的非常剧烈的流动条件。然而，只有约 1 m 的总未氧化 nZVI 被运输，并且<2%的注入 nZVI 浓度达到了该距离。实验数据还表明，在注入过程中地下水流动发生了变化，可能是由于氢气泡的形成，导致 nZVI 偏离了目标流道。铁羽流的前缘在运输过程中完全被氧化。然而，在羽流内，nZVI 的氧化程度呈下降趋势，与含水层“还原剂需求”的逐渐耗尽一致。为了直接定量 nZVI 的运移程度，开发了一种分光光度法，结果表明，将未氧化的 nZVI 用于地下水修复可能会很困难。
