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

卡内基梅隆大学的学术功绩。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，将受益于纳米技术。环境保护局报告说，有机污染物的污染，特别是氯化挥发性有机化合物，是超级基金国家优先名单中超过一半的地点的主要担忧[在超级基金地点发现常见化学品，美国环保局，2003年]。与这些化合物相关的健康风险导致了过去30年来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，往往以单独的非水相液体(NAPL)形式留在地下。残留的NAPL水池作为污染物淋溶到地下水的长期来源，导致大量溶解污染物的羽流和非常长的修复时间。先前的研究表明，悬浮的纳米铁与NAPL反应，将它们转化为无毒产品。这项建议的主要目标是开发和优化聚合物组件，优先将含铁纳米颗粒定向到NAPL-水界面，以便修复活动可以集中在NAPL源。这项研究的重点是成功开发靶向纳米颗粒传递系统所需的界面行为。这些聚合物的设计具有多功能-它们将纳米铁分散到水中，以实现良好的水在多孔介质中的传输，最大限度地减少对矿物和天然有机物(NOM)表面的不良吸附，并优先锚定纳米颗粒，使其积聚在NAPL/水界面。实验指标包括聚合物对胶体稳定性的影响，通过多孔砂柱的传输，对矿物和NOM表面的模拟吸附，以及对NAPL/水界面的分配。嵌段共聚物的组成和结构将发生系统的变化。使用受控自由基聚合方案将提供对嵌段长度的严格控制。最后，将比较两种聚合物附着在纳米颗粒上的方式--可溶嵌段共聚物的物理吸附和从纳米颗粒表面接枝的嵌段共聚聚合物。使用流行的“泵和处理”技术达到NAPL清理目标通常需要几十年的时间，因为它们主要解决NAPL羽流，而不是污染源。因此，能源部目前倡导开发新的就地技术来修复其受污染的场地[能源部场地地下水响应行动优化指南》，美国能源部环境管理办公室，2002年。拟议的纳米颗粒系统被设想为一种新的原位修复技术的基础，该技术有可能通过直接针对源头而不是管道的修复行动来加快清理速度。一名博士生将通过这项拨款接受研究培训。通过本科生参与这项研究，特别是通过利用卡内基梅隆大学的少数民族本科生暑期学院，进一步的教育收益将会增加。参与活动的学生和教职员工将为卡内基梅隆大学的工程你的未来计划准备动手的“智能聚合物”和“环境中的纳米技术”模块，该计划旨在提高匹兹堡地区女高中生的技术意识。

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.