Development of a Copolymer-Based System for Targeted Delivery of Nanoparticulate Iron to Environmental Non-Aqueous Phase Liquids

摘要- 0521721卡耐基梅隆大学。地下土壤和地下水的有机污染是一个广泛而令人烦恼的环境问题，它将从纳米技术中受益。环境保护署报告说，有机污染物的污染，特别是氯化挥发性有机化合物，是超过一半的超级基金国家优先列表站点的主要问题[超级基金站点发现的常见化学品，美国环保局，2003年]。过去30年来，与这些化合物相关的健康风险导致了广泛但相对不成功的补救努力。过去修复工作的有限成功主要是因为大多数有机污染物在水中的溶解度有限，并且倾向于在地下保持独立的非水相液体（NAPL）。残留的NAPL池作为污染物浸出到地下水的长期来源，导致大量溶解的污染物和非常长的修复时间。先前的研究表明，悬浮铁纳米颗粒与NAPLs反应，将其转化为无毒产物。本研究的主要目标是开发和优化聚合物组件，使含铁纳米颗粒优先靶向NAPL-水界面，从而将修复活性集中在NAPL源上。研究的重点是成功开发靶向纳米颗粒递送系统所需的界面行为。这些聚合物被设计成多功能的——它们将铁纳米粒子分散到水中，通过多孔介质具有良好的水运输性，最大限度地减少对矿物和天然有机物质（NOM）表面的不良吸附，并优先锚定纳米粒子在NAPL/水界面积聚。实验指标包括聚合物对胶体稳定性的影响、通过多孔砂柱的输送、对模拟矿物和NOM表面的吸附以及对NAPL/水界面的分配。嵌段共聚物的组成和结构将系统地变化。使用可控自由基聚合方案将提供对链段长度的严格控制。最后，将比较聚合物与纳米颗粒的两种附着模式——可溶性嵌段共聚物的物理吸附和嵌段共聚物从纳米颗粒表面接枝。更广泛的影响。使用目前流行的“泵送处理”技术，通常需要几十年的时间才能达到NAPL的清理目标，因为它们主要针对的是NAPL羽流，而不是源头。因此，能源部目前提倡开发新的原位技术来修复其受污染的场地[优化能源部场地地下水响应行动指南，美国能源部环境管理办公室，2002年]。所提出的纳米颗粒系统被设想为一种新的原位修复技术的基础，它有可能通过直接针对源头而不是羽流的修复行动来加速清理。一名博士生将通过该资助接受研究培训。通过本科生参与研究，特别是利用卡内基梅隆大学的少数民族本科生暑期学院，进一步的教育效益将会增加。参与的学生和教师将为卡内基梅隆大学的“工程你的未来”项目准备动手操作的“智能聚合物”和“环境中的纳米技术”模块，该项目旨在提高匹兹堡地区女高中生的科技意识。

ABSTTACT - 0521721Carnegie Mellon UniversityIntellectual Merit. Organic contamination of subsurface soil and groundwater is an extensive and vexing environmental problem that stands to benefit from nanotechnology. The Environmental Protection Agency reports that contamination by organic pollutants, especially chlorinated volatile organic compounds, are primary concerns at over half of the Superfund National Priorities List sites [Common Chemicals Found at Superfund Sites, U.S. E.P.A., 2003]. Health risks associated with these compounds have led to an extensive, but relatively unsuccessful, remediation effort for the past 30 years. The limited success of past remediation efforts is primarily because most organic pollutants have limited solubility in water and tend to remain as a separate non-aqueous phase liquid (NAPL) in the subsurface. Residual NAPL pools act as long-term sources for contaminant leaching to the groundwater, resulting in large plumes of dissolved contaminants and very long remediation times.Prior research indicates that suspended iron nanoparticles react with NAPLs to convert them to non-toxic products. The major goal of this proposal is to develop and optimize polymer assemblies that preferentially target iron-containing nanoparticles to the NAPL-water interface, so the remediation activity can be concentrated at the NAPL source. The research focuses on the interfacial behaviors that are required to successfully develop a targeted nanoparticle delivery system. The polymers are designed to be multifunctional - they disperse the iron nanoparticles into water for good aqueous transportability through porous media, minimize undesirable adsorption to mineral and natural organic matter (NOM) surfaces, and preferentially anchor nanoparticles to accumulate at the NAPL/water interface. Experimental metrics include the polymers' effects on colloidal stability, transport through porous sand columns, adsorption to model mineral and NOM surfaces, and partitioning to the NAPL/water interface. The composition and architecture of the block copolymers will be systematically varied. Use of controlled radical polymerization schemes will provide tight control over block lengths. Finally, two modes of polymer attachment to the nanoparticle will be compared - physisorption of soluble block copolymers and block copolymer grafting from nanoparticle surfaces.Broader Impact. Several decades are typically required to reach NAPL cleanup targets using the prevailing "pump-and-treat" technologies, because they address primarily the NAPL plume, not the source. Accordingly, the Department of Energy currently advocates the development of novel in situ technologies to remediate its contaminated sites [Guidance for Optimizing Ground Water Response Actions at Department of Energy Sites, U.S. D.O.E. Office of Environmental Management, 2002]. The proposed nanoparticle system is envisioned as the basis for a new in situ remediation technology with the potential to accelerate cleanup by directly targeting remediation action to the source, rather than the plume.One Ph.D. student will receive research training through this grant. Further educationalbenefits will accrue through the involvement of undergraduate students in the conduct of the research, especially by leveraging Carnegie Mellon's Summer Institute for MinorityUndergraduate Students. Participating students and faculty will prepare hands-on "smartpolymer" and "nanotechnology in the environment" modules for Carnegie Mellon's Engineering Your Future program that increases technology awareness among female high school students in the Pittsburgh area.