Trace Metal Interactions with Fly Ash in Combustion Flue Gas

砷、汞和硒作为微量金属（TMs）存在于煤的矿物质和有机物中，并可能在煤转化过程中排放到环境中。拟议研究工作的最终目标是了解与烟气接触的矿物表面上的异质TM形态与飞灰颗粒的大小和化学相的关系，这对了解其在整个环境中的生命周期以及潜在毒性具有更广泛的影响。从催化，地球化学，表面化学和燃料燃烧科学的基础知识将汇编，应用，并在拟议的工作中推进。通过考虑与地下水和燃料排气系统相关的tms -界面系统的共性和差异，可以突出地质和燃料化学观点的协同耦合。金属氧化物单晶表面的地球化学研究将为理解燃料燃烧颗粒束缚的TM排放提供必要的框架。此外，在广泛的相关条件下，将实验和理论方法结合起来研究TMs与粉煤灰颗粒的相互作用，将为反应产物的封存机理和稳定性提供新的信息。由于拟议的研究将首次集中于高水平飞灰的表征和测试，并与理论模型紧密结合，以确定模拟燃烧烟气中的多相TM反应性，因此将获得知识价值。此外，这些项目正在使用一种基于质谱法的自主设计的新型实验技术，直接确定烟气中各种形式的TM。这样就可以测定粉煤灰颗粒的氧化还原活性和吸附活性。通过使用基于这项工作结果的软件包，世界各地的主要公用事业公司和技术开发人员确定了最大限度地减少有毒TMs释放到大气中的最有效策略，所提出的努力的更广泛影响是显而易见的。此外，pi通过合作与行业直接联系，这将为参与研究的学生提供暑期实习机会。拟议工作的结果还将提供这些物种进入环境后TM生命周期的指示。

Arsenic, mercury, and selenium exist as trace metals (TMs) in minerals and organic matter in coal and may be emitted to the environment during coal conversion processes. The ultimate goals of the proposed research efforts are to understand heterogeneous TM speciation on mineral surfaces in contact with flue gases as a function of the size and chemical phase of the fly ash particles, with broader impacts toward understanding their life cycle throughout the environment in addition to their potential toxicity. Foundational knowledge from catalysis, geochemistry, surface chemistry, and fuel combustion science will be compiled, applied, and advanced in the proposed work. The synergistic coupling of geological and fuel chemistry perspectives can be highlighted by considering the commonalities and differences of the TMs-interface systems relevant to both ground water and fuel exhaust systems. Geochemical studies of well-characterized single crystal surfaces of metal oxides will provide the required framework for understanding fuel combustion particle-bound TM emissions. In addition, the integration of experimental and theoretical approaches to the interaction of TMs with fly ash particles under a broad range of relevant conditions will result in new information on sequestration mechanisms and stability of reaction products.Intellectual Merit will be achieved since the proposed investigations will be the first of their kind focusing on high-level fly ash characterization and testing closely coupled with theoretical models to determine heterogeneous TM reactivity in simulated combustion flue gas. Additionally, the PIs are using a novel self-designed experimental technique based on mass spectrometry to directly speciate the various forms of TM in flue gas. In this way, both redox and sorption activity of the fly ash particles will be determined. The Broader Impacts of the proposed efforts are evident through the use of software packages based upon results of this work by major utility companies and technology developers worldwide to determine the most effective strategies of minimizing the release of toxic TMs into the atmosphere. Additionally, the PIs have direct links to industry through collaborations, which will facilitate summer internships for students involved in the research. Results of the proposed work will also provide indication of the TM life cycle once these species enter the environment.