NIRT: Experimental and Theoretical Investigations of Aqueous Geochemical Interfaces - The Role of Nanoscale and Molecular Structures in Dictating Environmental Reactivity

培训本提案的重点是对氧化铁表面结构和反应性进行分子和纳米尺度研究的跨学科方法。拟议活动的智力价值：这里提出的研究将利用最先进的实验和理论方法，提供关于铁氧化物反应性的基本控制的独特信息。使用单晶衬底和赤铁矿纳米颗粒复合材料的实验将被用来确定与污染物金属离子的吸附有关的反应性趋势，以及这些趋势如何随表面取向、表面质量以及与“表面修饰物种”的反应而变化。拟议技术的互补性将允许在协调一致和协同的努力中寻求多种调查途径，并将导致与分离的独立研究相比，更好地了解正在调查的系统。该方法还充分利用了同步加速器表面结构技术和周期性从头计算方法的最新进展，克服了目前纳米粒子原位表面结构研究的局限性。这项工作的主要贡献之一将是解释分子规模、表面结构和纳米级表面形貌/缺陷密度方面的反应趋势。这将使重要的结垢问题得以解决，因为随着颗粒尺寸减小到纳米级，表面缺陷对反应活性的影响预计会急剧增加。这个研究小组特别适合于跨学科合作，旨在获得与环境界面化学有关的矿物表面结构和反应性的基本信息。拟议活动的广泛影响：纳米级固体/水溶液界面上的化学过程对环境化学和地球化学以及依赖于表面反应的各种技术领域，如多相催化和腐蚀控制，具有深远的影响。这里提出的工作将改善对金属离子在矿物表面(和从矿物表面释放)的预测，这最终将导致用于评估污染物风险和设计污染物修复策略的定量模型的改进。在追求该项目的技术目标的同时，将把重点放在为本科生、研究生和博士后提供教育机会上。学生参与者将参与这个项目的所有方面，从而提供基于同步加速器的实验、从头算电子结构计算和分析实验室实践的研究经验。因此，该项目的主要影响之一将是培养下一代科学家，包括妇女和少数群体，他们在分子环境科学的理论和技术方面接受过良好的培训，分子环境科学是高度跨学科的，由于环境系统的复杂性，在理解基本化学过程方面面临重大挑战。这项工作的其他教育影响将体现在成员机构设施和专门知识的发展以及通过同行评议的出版物和专题介绍向更广泛的科学界和普通社会传播成果。

0404400TrainorThe focus of this proposal is an interdisciplinary approach to molecular and nanoscale investigations of iron-oxide surface structure and reactivity. Intellectual merit of the proposed activity: The research proposed here will utilize state-of-the-art experimental and theoretical methods to provide unique information about the fundamental controls on reactivity of iron-oxides. Experiments using both single crystal substrates and nanoparticle composites of hematite will be used to determine reactivity trends with respect to adsorption of contaminant metal ions, and how these vary with surface orientation, surface quality, and reaction with "surface modifying species". The complementary nature of the proposed techniques will allow multiple avenues of investigation to be pursued in a coherent and synergistic effort and will result in a better understanding of the systems under investigation as compared with decoupled, independent studies. The proposed methodology also overcomes current limitations on in-situ surface structural studies of nanoscale particles by taking full advantage of recent advances in synchrotron-based surface structural techniques and periodic ab-initio methods. One of the main contributions of this work will be to explain reactivity trends in terms of molecular scale surface structure and nanoscale surface topography/defect density. This will allow the important question of scaling to be addressed since the effects of surface defects on reactivity are anticipated to increase dramatically as particle size decreases to the nanometer scale. This research team is particularly well qualified for an interdisciplinary collaboration aimed at obtaining fundamental information on mineral surface structure and reactivity relevant to the environmental interface chemistry.Broader impacts of the proposed activity: Chemical processes at nanoscale solid/aqueous solution interfaces have far-reaching impacts in environmental chemistry and geochemistry, as well as in various areas of technology that depend on surface reactions, such as heterogeneous catalysis and corrosion control. The work proposed here will lead to improved predictions about metal ion sequestration on (and release from) mineral surfaces, which will ultimately lead to improvements in quantitative models used for assessment of contaminant risk and the design of contaminant remediation strategies. While pursing the technical goals of this project, a major emphasis will be placed on providing educational opportunities to undergraduate, graduate, and post-doctoral students. Student participants will be involved in all aspects of this project, thereby providing research experience in synchrotron-based experimentation, ab-initio electronic structure calculations, and analytical laboratory practices. Thus one of the main impacts of this project will be to produce the next generation of scientists, including women and minorities, who are well trained in the theory and techniques of molecular environmental science, which is highly interdisciplinary and presents major challenges in terms of understanding fundamental chemical processes due to the complexity of environmental systems. Additional educational impact of this work will be reflected in the development of facilities and expertise at the member institutions and by dissemination of results to the broader scientific and general community through peer reviewed publications and presentations.