Characterization of Adsorption Complexes at Water/Solid Interfaces

离子在水/固体氧化物和水/粘土中的分配 在分子水平上对界面的了解还很有限，但 关于表面复合物的详细结构信息是 对于许多界面的定量描述是必要的 流程. 这些过程在许多领域发挥着重要作用， 包括地球化学、海洋学和环境 工程. 拟议的工作将利用高强度， 波长可调谐同步辐射与X射线吸收 光谱学（XAS），特别是扩展X射线吸收精细 结构（EXAFS）和X射线吸收近边结构 （XANES），以获得最近的直接，现场测量- 邻居，以及在可能的情况下，下一个邻居距离， 身份，协调数，在有利的系统中， 固体表面吸附质离子和阳离子之间的距离。 这些信息将用于帮助定义 表面复合物的组成和结构，并区分 在吸附、吸收、沉淀和共沉淀中。 研究了Pb ~（2+）、Sr ~（2+）、CO ~（2+）、Cu ~（2+）、 SeO_4/2-和SeO_3/2-作为吸附质，以及Geothite，γ-Al_2 O_3， 金红石和高岭石作为吸附剂。 拟定的研究将 提供详细的成分和结构信息， 吸附复合物，并有机会比较结果 通过几种方法获得。 这也将提供一个机会， 测试和完善现有的吸附理论模型 流程.

The partitioning of ions at water/solid oxide and water/clay interfaces is poorly understood at the molecular level, yet detailed structural information about surface complexes is essential for quantitative description of many interfacial processes. These processes play fundamental roles in many fields, including geochemistry, oceanography, and environmental engineering. The proposed work will utilize high-intensity, wavelength-tunable synchrotran radiation and X-ray Absorption Spectroscopy (XAS), specifically Extended X-Ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES), to obtain direct, in-situ measurements of nearest- neighbor, and where possible, next-neighbor distances and identities, coordination numbers, and in favorable systems, distances between adsorbate ions and cations in the solid surface. This information will be used to assist in the definition of composition and structure of surface complexes and to distinguish among adsorption, absorption, precipitation, and coprecipitation. Ten systems will be studied: involving Pb2+, Sr2+, CO2+, Cu2+, SeO4/2-, and SeO3/2- as adsorbates, and geothite, gamma-Al2O3, rutile, and kaolinite as adsorbents. The proposed study will provide detailed compositional and structural information about adsorption complexes, and an opportunity to compare results obtained by several methods. It will also provide an opportunity to test and refine current theoretical models for adsorption processes.