Thermodynamics and Redox Reactivity of Birnessite

水钠锰矿的热力学和氧化还原反应性

• 批准号: 2304711
• 负责人: Christopher Gorski
• 金额: $ 42.53万
• 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: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2304711&HistoricalAwards=false
• 关键词: Thermodynamics; Redox; Reactivity; Birnessite

With support from the Environmental Chemical Sciences Program in the Division of Chemistry, Christopher Gorski and Peter Heaney and their graduate students at Pennsylvania State University will study chemical reactions that occur at the interface between minerals and water. These reactions are important because they play a significant role in determining how environmental contaminants, such as toxic metals and hazardous organic compounds, behave in the environment and in water treatment systems. The project focuses on birnessite, which is a highly reactive manganese oxide commonly found in the environment. The rate at which birnessite transforms environmental contaminants present in water can depend on the properties of the birnessite and the water chemistry, but there is currently no quantitative method for determining why. To address this gap, the project will characterize the elemental composition, oxidation state, crystal structure, aggregation state, and surface charge of birnessite in various types of water and determine how quickly different environmental contaminants react with birnessite under the same conditions. To broaden the societal and scientific impact of the project, the researchers will also develop a workshop to teach other scientists and engineers how to use electrochemical methods to study minerals, and organize a demonstration called “Mysterious Manganese Minerals” at an outreach event for grade 6-12 young women interested in STEM (science, technology, engineering and mathematics) fields.This project will use a combination of mediated electrochemical techniques, spectroscopic analyses, and contaminant fate studies to thoroughly characterize birnessite and its reactivity. The project has three objectives with sequentially increasing complexities: (1) to determine how and why the oxidation state of Mn in sodium birnessite influences its thermodynamic properties and reactivity at pH 5.0; (2) to determine how and why the type and concentration of cations in solution and the pH influence birnessite’s thermodynamic properties and reactivity and (3) to determine if the relationships developed in first two objectives can predict contaminant oxidation rates in complex waters containing multiple cations and/or natural organic matter. If successful, this work will provide the environmental chemistry and geochemistry communities with a method for estimating the thermodynamic properties of birnessite under a range of solution chemistries. The work will also create a framework for characterizing the thermodynamic properties of other complex environmentally relevant minerals in the future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在化学系环境化学科学项目的支持下，宾夕法尼亚州立大学的克里斯托弗·戈尔斯基（Christopher Gorski）和彼得·希尼（Peter Heaney）以及他们的研究生将研究矿物和水之间发生的化学反应。这些反应很重要，因为它们发挥着重要作用。在确定有毒金属和有害有机化合物等环境污染物在环境和水处理系统中的作用方面，该项目重点关注水钠锰矿，这是一种在环境中常见的高活性锰氧化物。水钠锰矿对水中存在的环境污染物的转化取决于水钠锰矿的性质和水的化学性质，但目前没有定量方法来确定原因。为了解决这一差距，该项目将表征元素组成、氧化态、晶体结构、研究人员将研究不同类型水中水钠锰矿的聚集状态和表面电荷，并确定不同环境污染物在相同条件下与水钠锰矿反应的速度。还举办了一个讲习班，教其他科学家和工程师如何使用电化学方法来研究矿物，并在针对 STEM（科学、技术、工程和该项目将结合使用介导电化学技术、光谱分析和污染物归宿研究来彻底表征水钠锰矿及其反应性。该项目具有三个复杂性依次增加的目标：(1)确定钠水钠锰矿中 Mn 的氧化态如何以及为何在 pH 5.0 下影响其热力学性质和反应性；(2) 确定溶液中阳离子的类型和浓度以及 pH 值如何以及为何影响水钠锰矿的热力学性质和反应性以及 (3 ）以确定前两个目标中建立的关系是否可以预测含有多种阳离子和/或天然有机物的复杂水中的污染物氧化率。如果成功，这项工作将提供环境化学。这项工作还将创建一个框架，用于表征未来其他复杂环境相关矿物的热力学性质。该奖项反映了 NSF 的法定使命，并具有在一系列溶液化学条件下估计水钠锰矿热力学性质的方法。通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。