Energetics and Stability of Geologically-Confined Water

地质封闭水的能量学和稳定性

• 批准号: 0819769
• 负责人: John Jaeger
• 金额: $ 27.38万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0819769&HistoricalAwards=false
• 关键词: Energetics; Stability; Geologically; Confined; Water

Water confined in Å- to nm-scale pores is volumetrically and chemically important in surficial and near surface geological environments. Partitioning of water between bulk liquid and vapor phases and water confined in spaces within and between minerals plays a critical role in determining the fate of geochemical and geobiological processes. Despite considerable effort over the past several decades focused on the properties of confined water, rigorous thermodynamic models permitting simultaneous consideration of confined water stability relative to bulk water that are consistent with widely employed geochemical models are generally not available. In part, this is due to a paucity of physical chemical models permitting quantitative description of the hysteresis that is commonly observed between sorption and desorption of confined water. The present study addresses these needs through a combination of equilibrium observations, calorimetric measurements, and thermodynamic modeling of a selected suite of systems containing confined water. Model zeolite and nanoporous systems exhibiting hysteretic sorption/desorption behavior will be studied in order to test a newly developed thermodynamic model that shows promise in predicting hysteretic behavior. In addition, two other types of systems will be studied to fill in gaps currently present in the understanding of the factors controlling the stability of confined water: a) pure silica zeolites in which water molecules do not solvate ions; and c) zeolite systems containing confined water that is only bonded to ions. Water in these systems exhibits ?endmember? structural states, that when combined form the environments found in most previously studied microporous confined water systems (that is, those containing water molecules that both solvate ions and interact with the confining medium). Scientific outcomes: The results of this study will be synthesized through thermodynamic modeling to describe the stability of confined water molecules as a function of temperature, pressure, and the chemical potential of water. The resulting thermodynamic data and models will significantly expand capabilities for assessing the relative stability and behavior of confined water molecules in a thermodynamic framework that is congruent with standard practices in geochemical thermodynamics. Models describing hysteretic behavior in the systems studied will provide a heuristic basis for macroscopic thermodynamic description of other systems exhibiting this behavior. Broader impacts: The proposed study will provide enhanced educational opportunities for students at the University of Florida and will lead to widespread availability of the data and thermodynamic models. Graduate and undergraduate student involvement in the project is integral for its success. Students participating in this project will receive training and experience in modern experimental methods and thermodynamic analysis. In addition, the methods of the proposed study will be used to develop innovative classroom exercises to give students hands-on experience in thermochemical methods in the P.I.?s physical geochemistry course. Data generated in the study will be disseminated not only as publications in international scholarly journals, but will also be available for free download on the internet.

在Å-至NM尺寸的孔中，水在表面和近地面地质环境中具有体积和化学重要性。在矿物质和矿物质之间限制的散装液体和蒸气相以及水之间的水分配在确定地球化学和地球学过程的脂肪中起着至关重要的作用。尽管在过去的几十年中，大量努力集中在受限水的特性上，但严格的热力学模型允许简单地考虑相对于散装水的密闭水稳定性，这些稳定性与广泛使用的地球化学模型一致。在某种程度上，这是由于缺乏物理化学模型允许对滞后的定量描述，而滞后通常观察到滞后和解吸受限水之间。本研究通过均衡观测，Calolimetric测量以及所选系统套件的热力学建模的结合来解决这些需求。为了测试新开发的热力学模型，表现出滞后吸附/解吸行为的模型沸石和纳米多孔系统将进行研究，该模型显示出预测滞后行为的希望。此外，将研究其他两种类型的系统，以填补当前在理解控制限水稳定性的因素时存在的空白：a）水分子无法解决离子的纯硅沸石； c）含有仅与离子粘合的封闭水的沸石系统。这些系统中的水显示？结构状态，当组合形式时，在大多数先前研究的微孔约束水系统中发现的环境（即，那些含有溶解离子并与隔离培养基相互作用的水分子的环境）。科学结果：这项研究的结果将通过热力学建模合成，以描述限制水分子的稳定性，这是温度，压力和水的化学潜力的函数。所得的热力学数据和模型将显着扩大在热力学框架中评估受限水分子的相对稳定性和行为的能力，该框架与地球化学热力学的标准实践一致。在研究系统中描述滞后行为的模型将为宏观的热力学描述提供此行为的宏观热力学描述。更广泛的影响：拟议的研究将为佛罗里达大学的学生提供增强的教育机会，并将导致数据和热力学模型的广泛供应。研究生和本科生参与该项目的成功是其成功的组成部分。参加该项目的学生将获得现代实验方法和热力学分析的培训和经验。此外，拟议的研究的方法将用于开发创新的课堂练习，以在P.I.s的物理地球化学课程中为学生提供热化学方法的动手体验。研究中生成的数据不仅将作为国际科学期刊的出版物传播，而且还可以在互联网上免费下载。