NIRT: Nanoparticle Fe as a Reactive Constituent in Air, Water, and Soil

NIRT：纳米颗粒铁作为空气、水和土壤中的活性成分

• 批准号: 0506679
• 负责人: Michelle Scherer
• 金额: $ 140万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0506679&HistoricalAwards=false
• 关键词: NIRT; Nanoparticle; Fe; Reactive; Constituent

The goal of the proposed work is to understand the reactivity of iron (Fe) oxide nanoparticles inair, water, and soil environments. Fe oxide particles in the nanometer size range ( 100 nm) areubiquitous in nature and their occurrence ranges from ultra-fine mineral dust in the atmosphere tonanocrystalline precipitates in the hydrosphere. Research into the reactivity of nanoparticle Fe oxides hasbeen primarily aimed at understanding the bonding characteristics of atoms adsorbed at the surface. It isnow recognized, however, that the behavior of Fe in the environment is strongly influenced by bacteriallydriven redox reactions, as well as the local chemistry and nature of mineral surfaces in rocks and soils,and by the presence of water. Therefore, detailed investigations of the redox chemistry of Fe oxidenanoparticles under conditions analogous to nature are critical to understanding the role of these tinyparticles in the cycling of Fe in the environment.The proposed research will use advanced spectroscopic and analytical techniques, in conjunctionwith selective isotope labeling, to investigate redox processes occurring at the surface of Fe oxidenanoparticles in the presence of water. Of particular interest is the bacterially driven interaction betweenaqueous Fe, and mineral and cell surfaces, as well as redox reactions occurring during (i) Fe isotopeexchange, (ii) transport of atmospheric Fe mineral dust, (iii) pollutant reduction, and (iv) microbial Feoxidation. The experiments will use well characterized Fe oxide nanoparticles in batch and columnreactors designed to mimic natural conditions by varying biogeochemical conditions, including microbe,mineral, and water composition, as well as flow conditions.Intellectual Merit. Despite the key role of Fe(III)-Fe(II) reactions in environmental and industrialapplications, heterogeneous redox reactions occurring on nanoscale Fe oxides have been largely unexplored.This is due, in large part, to the analytical and spatial complexities of studying heterogeneous reactions of Fein the presence of water. The proposed methodology overcomes this obstacle by using an innovativecombination of 57Fe Mossbauer spectroscopy and high precision aqueous isotope ratio measurements tosimultaneously measure isotope specific oxidation states and concentrations of Fe at the Fe oxide-waterinterface. This approach, in tandem with X-Ray photoelectron spectroscopy (XPS) and transmission electronmicroscopy (TEM), will provide new information on how and where redox reactions occur on Fe oxidenanoparticles. The synergistic blend of expertise in Fe geochemistry, microbial Fe respiration, andatmospheric Fe mineral dust brought together with the proposed NIRT provides an unparalleled opportunityto study redox reactions involving Fe oxide nanoparticles during multiple components of the Febiogeochemical cycle. Observing reactivity . particle size trends for four diverse, but related reactionsprovide a powerful mechanism to identify new phenomena that are unique to oxide particles within thenanometer size range.Broader Impacts. An innovative combination of spectroscopic and isotopic techniques, in additionto comprehensive mineral characterization methods, will result in an improved understanding of the behaviorof Fe oxide nanoparticles in air, water, and soil. Our findings will directly impact newly developing theorieson global carbon cycling (via microbial Fe respiration and atmospheric deposition of Fe in the ocean), as wellas challenge our current understanding of important environmental and industrial processes includingdegradation of soil, sediment, and water quality, the evolution of earth.s geologic/magnetic record (via Feisotope biosignatures), accelerated rates of corrosion, and condensation processes (which may have led to theorigin of life on earth and biological activity on Mars). The exploratory, interdisciplinary nature of theproposed activity will provide excellent training for graduate, undergraduate, and high school students.Students, as well as participating scientists, will gain expertise in a variety of spectroscopic and microscopictools through three hands-on Nanoscale Processes in the Environment Summer Workshops. During theworkshop, students will collect, analyze, and interpret data from their own samples. Bimonthly .Fe Oxides inthe Environment. student forums will also be established at each university. The overall goal is to exposestudents to new ideas and to provide a forum for the interdisciplinary discussion of students. ideas throughoutthe year. Finally, a new initiative, .Geology and Art., will be launched through the Geology Museum atU.W. Madison to educate the public about Fe nanoparticles. This NIRT addresses the NSE research andeducation theme .Nanoscale Processes in the Environment..

这项工作的目标是了解氧化铁纳米颗粒在空气、水和土壤环境中的反应性。纳米级（100nm）的氧化铁颗粒在自然界中普遍存在，其存在范围从大气中的超细矿物粉尘到水圈中的纳米晶沉淀物。研究纳米铁氧化物的反应性主要是为了了解表面吸附原子的键合特性。然而，现在人们认识到，铁在环境中的行为受到细菌驱动的氧化还原反应、岩石和土壤中矿物表面的局部化学和性质以及水的存在的强烈影响。因此，在类似于自然的条件下，对铁氧化物颗粒的氧化还原化学的详细研究对于理解这些微小颗粒在环境中铁循环中的作用至关重要。拟议的研究将使用先进的光谱和分析技术，结合选择性同位素标记，研究在存在水的情况下铁氧化物颗粒表面发生的氧化还原过程。特别令人感兴趣的是细菌驱动的水中铁与矿物和细胞表面之间的相互作用，以及在以下过程中发生的氧化还原反应：(i)铁同位素交换，（ii）大气中铁矿物粉尘的运输，（iii）污染物减少，以及（iv）微生物氧化。实验将在间歇式和柱状反应器中使用表征良好的氧化铁纳米颗粒，通过改变生物地球化学条件（包括微生物、矿物和水成分）以及流动条件来模拟自然条件。知识价值。尽管Fe(III)-Fe（II）反应在环境和工业应用中发挥了关键作用，但在纳米级Fe氧化物上发生的非均相氧化还原反应在很大程度上尚未被探索。这在很大程度上是由于在水的存在下研究费恩的非均相反应的分析和空间复杂性。所提出的方法克服了这一障碍，通过使用57Fe穆斯堡尔光谱和高精度水同位素比值测量的创新组合，同时测量铁氧化物-水界面处的同位素特定氧化态和铁浓度。这种方法与x射线光电子能谱（XPS）和透射电子显微镜（TEM）相结合，将提供关于铁氧化物颗粒氧化还原反应如何以及在何处发生的新信息。在铁地球化学、微生物铁呼吸和大气铁矿物粉尘方面的专业知识的协同融合，以及拟议的NIRT，为研究铁生物地球化学循环的多个组成部分中涉及铁氧化物纳米颗粒的氧化还原反应提供了无与伦比的机会。观察反应性。粒径趋势的四种不同的，但相关的反应提供了一个强大的机制，以确定新的现象是独特的氧化颗粒在纳米尺寸范围内。更广泛的影响。除了全面的矿物表征方法外，光谱和同位素技术的创新组合将使人们更好地了解氧化铁纳米颗粒在空气、水和土壤中的行为。我们的发现将直接影响最新发展的全球碳循环理论（通过微生物铁呼吸和海洋中铁的大气沉积），并挑战我们目前对重要环境和工业过程的理解，包括土壤，沉积物和水质的退化，地球的进化。地球的地质/磁记录（通过铁同位素生物特征），加速的腐蚀和冷凝过程（这可能导致了地球上生命的起源和火星上的生物活动）。该活动的探索性、跨学科性质将为研究生、本科生和高中生提供极好的训练。学生，以及参与科学家，将获得专业知识，在各种光谱和显微镜工具通过三个动手纳米尺度过程在环境夏季研讨会。在研讨会期间，学生将从他们自己的样本中收集、分析和解释数据。两月一次的。环境中的铁氧化物。每所大学也将建立学生论坛。总体目标是让学生接触到新的思想，并为学生提供一个跨学科讨论的论坛。创意贯穿全年。最后，一项新的倡议。地质与艺术。，将通过华盛顿大学的地质博物馆发射。让公众了解铁纳米粒子。这个NIRT解决了NSE的研究和教育主题。环境中的纳米尺度过程…