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.

在地表和近地表地质环境中，限制在微米至纳米尺度孔隙中的水在体积和化学上是重要的。水在液相和气相之间的分配以及矿物内部和矿物之间的空间中的水在决定地球化学和地球生物学过程的命运方面起着关键作用。尽管在过去的几十年里，相当大的努力集中在承压水的属性，严格的热力学模型，允许同时考虑承压水相对于散装水的稳定性，是一致的广泛采用的地球化学模型一般是不可用的。在某种程度上，这是由于缺乏物理化学模型，允许定量描述的滞后现象，通常观察到的吸附和解吸承压水之间。本研究解决了这些需求，通过一个组合的平衡观测，量热测量，和热力学建模的一套选定的系统包含承压水。模型沸石和纳米多孔系统表现出滞后的吸附/解吸行为将进行研究，以测试一个新开发的热力学模型，显示在预测滞后行为的承诺。此外，两个其他类型的系统将被研究，以填补目前存在的差距，在了解的因素控制的封闭水的稳定性：a）纯硅沸石，其中水分子不溶剂化离子;和c）沸石系统包含封闭的水，仅结合到离子。在这些系统中的水展品？端元？结构状态，当结合时形成在大多数先前研究的微孔封闭水系统中发现的环境（即，含有溶剂化离子并与封闭介质相互作用的水分子的那些）。科学成果：本研究的结果将通过热力学建模来合成，以描述作为温度，压力和水的化学势的函数的承压水分子的稳定性。由此产生的热力学数据和模型将显着扩大能力，以评估相对稳定性和行为的承压水分子的热力学框架，是一致的地球化学热力学的标准做法。模型描述滞后行为的系统研究将提供一个启发式的基础，表现出这种行为的其他系统的宏观热力学描述。更广泛的影响：拟议的研究将为佛罗里达大学的学生提供更好的教育机会，并将导致数据和热力学模型的广泛可用性。研究生和本科生参与该项目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方面的培训和经验。此外，拟议的研究方法将被用来开发创新的课堂练习，让学生动手的热化学方法在PI？物理地球化学课程。研究中生成的数据不仅将作为国际学术期刊上的出版物传播，还将在互联网上免费下载。