Investigating the Surface Structure and Reactivity of Bulk and Nanosized Manganese Oxides

研究块状和纳米氧化锰的表面结构和反应性

• 批准号: 0544246
• 负责人: Donald Sparks
• 金额: --
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0544246&HistoricalAwards=false
• 关键词: Investigating; Surface; Structure; Reactivity; Bulk

EAR-0544246SPARKSResearch is proposed that investigates the chemical and physical properties of the environmentally important oxides of manganese (Mn) that play a central role in soil redox chemistry. It is well accepted in the geoscience community that Mn-oxides exist as coatings and as discrete particles in soils, in part with nano-dimensions. Their rich redox chemistry affects the mobility and bioavailability of environmental toxins including many metals and metalloids. Research will be focused primarily on the surface structure and chemical reactivity of both the bulk birnessite (MnO2) phase of Mn-oxide and also a nano-MnOOH phase under a variety of environmentally relevant conditions. In particular, a selection of advanced surface spectroscopic techniques, including attenuated total reflection infrared (ATR-FTIR) spectroscopy and synchrotron-based photoelectron spectroscopy (PES) will be used to develop a picture of the reacting Mn-oxide surface, such as determining the relative surface concentration of different Mn oxidation states, over a range of established soil pH values. These Mn-oxide surfaces will then be probed via reaction with aqueous arsenic oxyanions to establish the control that differences in Mn-oxide structure and reactivity exert on redox reactions in the environment.While birnessite, found in a wide range of soil environments, is a primary target of the proposed research, nano-sized Mn-oxides also exist in the environment and are of interest in the current research. Toward developing an understanding of the role that nano-Mn-oxides might play in low temperature geochemistry, research will investigate the reactivity and electronic structure of MnOOH nano-particles as a function of size. Nano-MnOOH with homogeneous size distributions from 20 to 80 A will be prepared and studied in solutions with varying pH and the As oxidation reaction will again be used as a probe for reactivity. This particular phase of the research project will not only develop an understanding of the size-reactivity relationship for Mn-oxide, but will in general contribute to the broader effort in the geochemical community to evaluate the importance of nano-chemistry in the environment.The proposed study has a significant educational and outreach component. First, NSF funds will be used to support and train a postdoctoral researcher at the University of Delaware and a graduate student at Temple University. Additionally, an undergraduate honors student at the University of Delaware will conduct research dealing with the project. The members of the research team will participate in a bi-annual meeting held alternatively at each participating institution in order to evaluate the progress of the research program and to disseminate new ideas and information. By virtue of this study being strongly interdisciplinary in nature, the scientific breadth of researchers in this project will benefit from the constant exchange of ideas and concepts between groups having expertise in diverse areas of soil and surface chemistry. This collaboration fits into the broader need for interdisciplinary studies to understand complex environmental chemistry.Since there is great concern on the part of citizens and policymakers in the State of Delaware and elsewhere on building housing developments on soils impacted by industrial and agricultural inputs of As, town hall meetings will be held in collaboration with personnel from the Delaware Department of Resources and Environmental Control, to inform the citizenry of our research. This form of outreach, along with direct contact with interested citizens at the University of Delaware College of Agriculture and Natural Resources yearly open-house (Ag Day), will be crucial to introducing Delawareans to the type, and significance, of environmental science and issues that are being addressed at academic institutions.

提议EAR-0544246SparkSresearch研究，研究在土壤氧化还原化学中起着核心作用的锰（MN）的化学和物理性质。在地球科学界，Mn-氧化物作为涂料和土壤中的离散颗粒的存在，部分是由纳米二维存在的。它们丰富的氧化还原化学会影响环境毒素的迁移率和生物利用度，包括许多金属和金属。研究将主要集中在MN-氧化物的大量Birnessite（MNO2）相的表面结构和化学反应性以及在各种与环境相关的条件下的纳米MNOOH相。特别是，包括减毒的总反射红外（ATR-FTIR）光谱和基于同步加速器的光电光谱（PES）的选择，包括减弱的表面光谱技术（PES），将用于开发反应MN-氧化物表面的图像，例如确定不同MN氧化状态的相对表面浓度，而不是Nation Sanditative convections conters condys ph。然后，将通过与砷氧水性反应来探测这些MN氧化物表面，以确定控制的控制，即Mn-氧化物结构和对环境中的氧化还原反应的反应性差异。在广泛的土壤环境中发现的Birnessite是众多的MN-N-氧化物的主要目标，但在环境中也存在于环境中，并且在环境中也存在于当前的研究中，并且在当前的研究中也存在。当前的研究和现有的研究。为了发展对纳米-MN氧化物在低温地球化学中可能起的作用的理解，研究将研究MNOOH纳米粒子的反应性和电子结构，这是大小的函数。将在具有不同pH的溶液中制备并研究具有均匀尺寸分布的纳米-MNOOH，AS氧化反应将再次用作反应性的探针。研究项目的这个特殊阶段不仅将对MN氧化物的尺寸反应关系有所了解，而且总体上将为地球化学社区的更广泛努力做出评估纳米化学在环境中的重要性。拟议的研究具有重要的教育和外展成分。首先，NSF资金将用于支持和培训特拉华大学的博士后研究员和Temple University的研究生。此外，特拉华大学的一名本科荣誉学生将进行与该项目有关的研究。研究小组的成员将参加在每个参与机构举行的两年一次的会议，以评估研究计划的进度并传播新的想法和信息。由于这项研究本质上是强烈的跨学科，因此该项目中研究人员的科学广度将受益于在土壤和表面化学领域具有专业知识之间的思想和概念之间的不断交流。这种合作符合对跨学科研究的更广泛的需求，以了解复杂的环境化学。由于特拉华州和其他地方的公民和政策制定者非常关注，这些公民和在其他地方建立住房发展，这些土壤受到工业和农业投入的影响，市政厅会议将与我们的公民部门合作，从而向我们的市政府提供了众多的委员会。这种宣传形式以及与特拉华大学农业与自然资源学院的感兴趣的公民年度开放式（AG Day）的直接联系将对于将特拉华州人引入到学术机构正在解决的环境科学和问题的类型和意义至关重要。