Time-Resolved Structural Analysis of Heavy Metal Cation Exchange Reactions in Anionic Clay and Manganese Oxide Nanoparticles

阴离子粘土和氧化锰纳米颗粒中重金属阳离子交换反应的时间分辨结构分析

• 批准号: 0125908
• 负责人: Peter Heaney
• 金额: $ 22.6万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125908&HistoricalAwards=false
• 关键词: Time; Resolved; Structural; Analysis; Heavy

HeaneyEAR-0125908Anionic clays and manganese oxides occur abundantly as nanocrystalline coatings on soil and sediment particles in surficial environments. They exhibit a remarkable facility for exchanging ions dissolved in aqueous fluids and act as major traps for anions and cations. The investigators of this proposal will apply a novel crystallographic approach to resolve mechanisms of cation exchange in layered double hydroxide and Mn oxide materials. Powdered samples will be monitored by synchrotron X-ray diffraction during the process of cation exchange. These experiments will yield the first time-resolved analyses of the structural distortions that occur to accommodate substitutions by transition metals in low-temperature minerals. Additionally, in concert with high-temperature infrared spectroscopy, synchrotron XRD analyses will be performed as samples are heated, allowing the structural manifestations of thermal decomposition to be correlated with cation exchange capacity.These studies will allow the investigators to capture intermediate transition steps that are overlooked by a more conventional static analysis of final run products. As the structural perturbations that are associated with chemical substitutions tend to stabilize the exchanged phases, these studies will indicate which factors limit the degree of exchange for selected cations. Consequently, these experiments will suggest approaches to the design of new remediation materials with amplified exchange characteristics.

Heaneyear-0125908植物粘土和锰氧化物在表面环境中的土壤和沉积物颗粒上大量出现，作为纳米晶涂层。 它们表现出非凡的设施，用于交换溶于水性液体的离子并充当阴离子和阳离子的主要陷阱。 该提案的研究者将采用一种新型的晶体学方法来解决分层双氢氧化物和MN氧化物材料中的阳离子交换机制。 在阳离子交换过程中，将通过同步加速器X射线衍射监测粉末状样品。 这些实验将对通过低温矿物质中的过渡金属适应替代的结构扭曲进行首次分解分析。 此外，在与高温红外光谱仪的一致过程中，同步子XRD分析将作为样品进行加热进行，从而使热分解的结构表现与阳离子交换能力相关。这些研究将使研究人员可以捕获更常规的统计分析的中间过渡步骤，这些中间过渡步骤被捕获了最终的最终统计分析。由于与化学取代相关的结构扰动倾向于稳定交换阶段，因此这些研究将表明哪些因素限制了所选阳离子的交换程度。 因此，这些实验将提出设计具有扩增交换特征的新补救材料的方法。