Collaborative Research: Ion Adsorption on Nanocrystalline Mineral Surfaces: Towards a Fundamental Understanding of Nanoparticles in the Environment

合作研究：纳米晶体矿物表面的离子吸附：对环境中纳米颗粒的基本了解

• 批准号: 0842526
• 负责人: Moira Ridley
• 金额: $ 36.63万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0842526&HistoricalAwards=false
• 关键词: Collaborative; Research; Ion; Adsorption; Nanocrystalline

The chemical and electrostatic interactions occurring at interfaces of crystalline metal-oxides and aqueous solutions are of fundamental importance in myriad geochemical, materials sciences and technological processes. Reactions of particular importance to geochemists that take place between minerals and fluids include, soil formation and weathering; uptake, transport and release of inorganic and organic contaminants; biomineralization; dissolution, aggregation and precipitation; and numerous other natural processes. A comparable broad list of interface reactions of relevance to the materials sciences and industry could also be presented. Intellectual Merit: The goal of this proposal is to investigate the effect of particle size on the chemical and electrostatic interactions between nanocrystalline metal-oxides and aqueous solutions. Nanosized particles are ubiquitous at the Earth?s surface, and may play a considerable role in biogeochemical and environmental processes. Furthermore engineered metal-oxide nanomaterials are used extensively in a variety of industrial applications and commercial products. The growing use of manufactured nanomaterials raises concern for the potential release of these particles into the environment. The role of nanoparticles (natural and manufactured) at the Earth?s surface is of importance because of the variation in the chemical and physical properties of these particles as a function of particle size. Equally, the large surface area of nanoparticles and variations in atomic structure possibly will change the surface reactivity of nanoparticles towards aqueous solutions as a function of particle size. No single experimental or theoretical technique will provide a coherent and comprehensive view of the properties of nanoparticle-solution interfacial reactions in the environment. Accordingly, the proposed research will integrate macroscopic experimental studies, molecular-scale computational studies, and surface complexation models. All three focus areas of this proposal will primarily investigate the interfacial behavior of anatase (TiO2) powders of discrete nanosize; additionally, the surface properties of MnO2 nanophases will be explored. The experiments will for the first time, provide a systematic, coherent and extensive experimental data set that will document fundamental differences in surface reactivity between nanoparticles and macroscopic particles of the same bulk material. The experiments will be performed over a range of temperatures (5 ? 75 °C) and solution compositions representative of those encountered at the Earth?s surface. The variable temperature studies will be the first to document the effect of temperature on nanoparticle surface reactivity. The experimental studies will be strongly coupled with theoretical studies. The molecular simulation studies will probe the atomic-scale properties of hydrated anatase nanoparticles, and will provide detailed information on surface bonding structures, H-bonding distributions, surface relaxation, and adsorption geometries. The ultimate goal of the proposed research is to merge the experimental and theoretical results into surface complexation models that can describe and predict interfacial properties that govern particle-size effects. Such an integrated approach is the state-of-the-art for interface science. Broader Impacts: The proposed studies will considerably advance fundamental understanding of the behavior of nanoparticles interacting with aqueous solutions at the Earth?s surface. Furthermore, the anticipated results will have wide-ranging application and relevance that extends well beyond the earth and environmental sciences; for instance, to materials sciences, chemistry, industry, and medical fields. For example, the controlled growth of nanoparticles and larger crystals from nanoparticles depends on aggregation, which in turn is influenced directly by particle-water interface chemistry. The students and post-doctoral associates involved in the project will receive training in both experimental and theoretical methods, learn how to integrate results from these approaches, and develop a more comprehensive understanding of nanoparticle interfaces. Moreover, the proposed studies are well suited to the involvement of both graduate and undergraduate students. All research results will be disseminated via publications in peer reviewed journals, and presented at national and international meetings.

结晶金属氧化物与水溶液界面的化学和静电相互作用在地球化学、材料科学和工艺过程中具有重要意义。对地球化学家来说，矿物和流体之间发生的特别重要的反应包括土壤形成和风化;无机和有机污染物的吸收、运输和释放;生物矿化;溶解、聚集和沉淀;以及许多其他自然过程。还可以提出与材料科学和工业有关的界面反应的一个相当广泛的清单。智力优势：本论文的目的是研究纳米晶金属氧化物与水溶液之间的化学和静电相互作用对颗粒尺寸的影响。纳米颗粒在地球上无处不在？的表面，并可能发挥相当大的作用，在地球化学和环境过程。此外，工程金属氧化物纳米材料广泛用于各种工业应用和商业产品。人造纳米材料的使用越来越多，引起了人们对这些颗粒可能释放到环境中的担忧。纳米粒子（天然的和人造的）在地球上的作用？由于这些颗粒的化学和物理性质随颗粒尺寸的变化而变化，因此颗粒的表面是重要的。同样，纳米颗粒的大表面积和原子结构的变化可能会改变纳米颗粒对水溶液的表面反应性，作为粒径的函数。没有一个单一的实验或理论技术将提供一个连贯的和全面的观点的纳米颗粒在环境中的溶液界面反应的性质。因此，拟议的研究将整合宏观实验研究，分子尺度的计算研究和表面络合模型。该提案的所有三个重点领域将主要研究离散纳米尺寸的MnO 2（TiO 2）粉末的界面行为;此外，还将探索MnO 2纳米相的表面性质。这些实验将首次提供一个系统的，连贯的和广泛的实验数据集，将记录纳米颗粒和相同散装材料的宏观颗粒之间的表面反应性的根本差异。实验将在一定的温度范围内进行（5？75 °C）和溶液组成的代表，在地球上遇到的？s表面。变温研究将首次记录温度对纳米颗粒表面反应性的影响。实验研究将与理论研究紧密结合。分子模拟研究将探测水合纳米粒子的原子尺度性质，并将提供有关表面键合结构，氢键分布，表面弛豫和吸附几何形状的详细信息。所提出的研究的最终目标是将实验和理论结果合并到表面络合模型中，该模型可以描述和预测控制颗粒尺寸效应的界面性质。这种综合方法是界面科学的最新发展。更广泛的影响：拟议中的研究将大大推进基本的理解纳米粒子与水溶液相互作用的行为在地球上？s表面。此外，预期结果将具有广泛的应用和相关性，远远超出地球和环境科学;例如，材料科学，化学，工业和医学领域。例如，纳米颗粒和来自纳米颗粒的较大晶体的受控生长取决于聚集，而聚集又直接受到颗粒-水界面化学的影响。参与该项目的学生和博士后将接受实验和理论方法的培训，学习如何整合这些方法的结果，并对纳米颗粒界面有更全面的了解。此外，拟议的研究非常适合研究生和本科生的参与。所有研究成果将通过在同行评审期刊上发表的出版物传播，并在国家和国际会议上发表。