Fate and Transport of Metal-Based Nanoparticles in the Subsurface

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。0854136 Pennell尽管在过去十年中纳米技术的快速发展，我们目前对纳米材料的命运和环境中的运输的理解仍然相当有限。 例如，目前还不知道大多数工程纳米材料将如何与土壤基质相互作用，它们的运输是否可以使用经典的颗粒过滤理论建模为胶体颗粒，或者不饱和条件如何影响纳米颗粒在天然土壤中的运输，保留和持久性。 虽然已经有一些努力致力于研究碳纳米材料在环境中的行为，但非常有限数量的研究集中在金属基纳米颗粒的运输上，这是一类特别重要的纳米材料，因为它们具有潜在的毒性并广泛用于个人护理产品。 出于这个原因，拟议的研究将集中在三个代表性的金属基纳米材料;纳米银（Ag），纳米二氧化钛（TiO 2）和纳米氧化锰（S）（MnOx）。 该研究计划旨在将详细的实验室实验与数学建模相结合，以阐明石英砂和天然土壤中金属基纳米颗粒的命运和运输机制。为了实现这一目标，该研究围绕四个具体任务进行，（1）金属基纳米颗粒悬浮液和土壤性质的表征，（2）测量水饱和条件下金属基纳米颗粒的传输和保留，（3）测量不饱和条件下金属基纳米颗粒的传输，以及（4）开发和验证用于预测基于金属的纳米颗粒在地下系统中的传输和持久性的数学模型。 特别是新的方面的研究计划包括考虑表面涂层和乳化剂中常用的防晒霜和化妆品含有二氧化钛和使用力体积显微镜图像沉积在沙粒表面的纳米粒子。从每个任务中收集的信息将被整合，以促进我们对多孔介质中金属基纳米颗粒传输机制的基本理解，最终目标是开发一个数值模拟器，可用于预测基于已知输入参数的工程纳米颗粒在地下的传输行为。 拟议的研究的智力价值在于两个领域的安全和可持续发展的纳米技术的关键;（1）我们的基本理解的进步金属基纳米材料的命运和运输多孔介质和（B）的发展和验证的数学模型，可用于模拟纳米粒子在地下运输。在这项工作中提出的实验研究和数学建模的独特耦合提供了严格验证的概念模型的纳米材料行为在不饱和和饱和多孔介质中，并最终在数值模拟器的发展能够预测纳米材料的命运和运输在一系列的条件下，可能会遇到在自然系统。我们预计，在这项工作中开发的实验参数和数学模型可以适用于预测其他纳米材料的命运和运输（例如，铁氧烷）。纳米颗粒在多孔介质中滞留的基本知识也可用于模拟含有纳米颗粒的饮用水或废水处理的过滤技术的性能。该项目的一个重要组成部分将是将教育倡议纳入研究人员的研究和教学活动，其目标是扩大所获知识的影响，使之超越期刊出版物和会议报告的传统框架。 这一目标将通过以下举措来实现：（a）吸收本科生进行综合实验和数学建模研究;（B）开发互动式多媒体教学工具;（c）招收女生和人数不足的少数民族学生。 教学材料，包括教程，说明性的案例研究和建模工具，将在一个专门的网站上发布，使学生和教师都可以探索过程中，管理的命运和运输的金属基纳米粒子在陆地环境中。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).0854136Pennell Despite the rapid development of nanotechnologies over the past decade, our current understanding of nanomaterial fate and transport in the environment remains quite limited. For example, it is not known how most engineered nanomaterials will interact with soil matrices, whether or not their transport can be modeled as colloidal particles using classic particle filtration theory, or how unsaturated conditions impact nanoparticle transport, retention and persistence in natural soils. Although some effort has been devoted to investigate the behavior of carbonaceous nanomaterials in the environment, a very limited number of studies have focused on the transport of metal-based nanoparticles, a particularly important class of nanomaterials because of their potential toxicity and widespread use in personal care products. For this reason, the proposed research will focus on three representative metal-based nanomaterials; nano-silver (Ag), nano-titanium dioxide (TiO2), and nano-manganese oxide(s) (MnOx). The research program is designed to couple detailed laboratory experimentation with mathematical modeling to elucidate mechanisms governing the fate and transport of metal-based nanoparticles in quartz sands and natural soils. To achieve this goal, the research is structured around four specific tasks, (1) characterization of metal-based nanoparticle suspensions and soil properties, (2) measure the transport and retention of metal-based nanoparticle under water saturated conditions, (3) measure the transport of metal-based nanoparticle under unsaturated conditions, and (4) develop and validate mathematical models for the prediction of metal-based nanoparticle transport and persistence in subsurface systems. Particularly novel aspects of the research plan include the consideration of surface coatings and emulsifying agents commonly used in sunscreens and cosmetic products containing TiO2 and the use of force-volume microscopy to image nanoparticles deposited on sand grain surfaces. Information gathered from each task will be integrated to advance our fundamental understanding of the mechanisms governing metal-based nanoparticle transport in porous media, with the ultimate goal of developing a numerical simulator that can be used to predict the transport behavior of engineered nanoparticles in the subsurface based on known input parameters. The intellectual merit of the proposed research lies in two areas critical to the safe and sustainable development of nanotechnologies; (1) advancement of our fundamental understanding of metal-based nanomaterial fate and transport in porous media and (b) development and validation of mathematical models that can be used to simulate nanoparticle transport in the subsurface. The unique coupling of experimental studies and mathematical modeling proposed in this work provides for rigorous validation of conceptual models of nanomaterial behavior in unsaturated and saturated porous media, and will culminate in the development of numerical simulator capable of predicting nanomaterial fate and transport over a range of conditions that might be encountered in natural systems. We anticipate that the experimental parameters and mathematical models developed in this work can be adapted to predict the fate and transport of other nanomaterials (e.g., ferroxane) in subsurface systems. The fundamental knowledge of nanoparticle retention in porous media can also be used to model the performance of filtration technologies for treatment of drinking or waste water containing nanoparticles.An essential component of the project will be the incorporation of education initiatives into the research and instructional activities of the investigators, with the goal of extending the impact of acquired knowledge beyond the traditional framework of journal publications and conference presentations. This goal will be achieved through the following initiatives: (a) the inclusion of undergraduate students conducting integrated experimental and mathematical modeling research, (b) the development of interactive, multi-media instructional tools, and (c) recruitment of female and underrepresented minority students. The instructional materials, consisting of tutorials, illustrative case studies and modeling tools, will be released on a dedicated web site so that students and instructors alike can explore processes that govern the fate and transport of metal-based nanoparticles in terrestrial environments.