Improving Permanganate Oxidations: Speciation, Pathways, Rates, and Products

改善高锰酸盐氧化：形态、途径、速率和产物

• 批准号: 1067075
• 负责人: Alan Stone
• 金额: $ 30.35万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1067075&HistoricalAwards=false
• 关键词: Improving; Permanganate; Oxidations; Speciation; Pathways

1067075StonePermanganate is widely employed in water supply plants to remove iron and manganese, taste and odor compounds, endocrine disruptors, and cyanobacterial toxins. It is employed in aquaculture as a fungicide. Permanganate reportedly dehalogenates some organic substrates, but this capability is not yet utilized in practice. Permanganate oxidations can involve six manganese oxidation states: +II, +III, +IV, +V, +VI, +VII. Manganese speciation and reactivity in response to ambient chemistry govern rates of substrate consumption and the identities of oxidation products. Many permanganate oxidations are autocatalytic; an intermediate or product catalyzes forward reaction. Better understanding of the effects of ambient chemistry on the speciation, pathways, rates, and products of permanganate oxidations would enable us to (i) accelerate permanganate oxidations, thereby improving effectiveness, and (ii) anticipate and avoid situations where oxidation products might be toxic or otherwise problematic.The objective of this research to provide the scientific/technical basis for improving the performance of permanganate oxidations. Emerging contaminants that possess both classical sites of permanganate oxidation (e.g. alkene groups) and nonclassical sites (oxygen and nitrogen heterocycles) will be included as representative substrates. Small changes in functional group identity and molecular structure will enable us to probe reaction mechanisms and develop structure-reactivity relationships. Capillary electrophoresis with UV detection, and HPLC with both UV and ESI-MS/MS detection, will be used to identify and quantify reaction intermediates and products. Autocatalysis may arise from (i) heightened substrate reactivity upon adsorption to hydrous manganese oxides (HMOs), (ii) disproportionation reactions between permanganate and lower Mn oxidation states (+II, +III, +IV) that boost Mn(V) and Mn(VI) concentrations, (iii) permanganate-substrate reactions that generate novel oxidants on surfaces or in solution. Reagent probes, as well as exploration of pH and major ion composition effects will help resolve among possible mechanisms. High resolution transmission electron microscopy (HRTEM), combined with selective area electron diffraction (SAED) and electron energy loss spectroscopy (EELS), will be used to characterize manganese (hydr)oxide solids generated by permanganate oxidations. They will explore the intermediate oxidation state manganese species identified and quantified using capillary electrophoresis.The unique combination of expertise in the PI's lab, i.e. inorganic reaction mechanisms, organic reaction mechanisms, and heterogeneous speciation determination, is needed to address the scientific/technical issues posed. By improving the efficiency of permanganate oxidations, and by shedding light on permanganate oxidation product identity and yields, the proposed work will make a significant contribution to the field of water quality.The PI's laboratory has developed several key concepts and tools in the area of metal-organic interactions in water. Nine women and five men have completed their Ph.D. training in the PI's laboratory, including eight currently holding tenure track appointments. The PI has helped organize outreach activities at the Rawlings Conservatory in Baltimore, and leads monthly "Science Demonstrations" at the Conservatory.

1067075 StonePercent广泛用于供水厂去除铁和锰、味道和气味化合物、内分泌干扰物和蓝藻毒素。 它在水产养殖中用作杀真菌剂。 据报道过氧化氢可使某些有机底物脱卤，但这种能力尚未在实践中得到利用。 过氧化氢氧化可涉及六种锰氧化态：+II、+III、+IV、+V、+VI、+VII。 锰的形态和反应性，以响应环境化学支配率的底物消耗和氧化产物的身份。 许多高锰酸盐氧化反应是自催化的;一个中间体或产物催化正反应。 更好地了解环境化学对高锰酸盐氧化的形态、途径、速率和产物的影响，将使我们能够（i）加速高锰酸盐氧化，从而提高效率，（ii）预测和避免氧化产物可能有毒或有其他问题的情况。 具有高锰酸盐氧化经典位点（例如烯烃基团）和非经典位点（氧和氮杂环）的新兴污染物将作为代表性底物。 官能团身份和分子结构的微小变化将使我们能够探测反应机理并发展结构-反应性关系。 将使用毛细管电泳（UV检测）和HPLC（UV和ESI-MS/MS检测）鉴别和定量反应中间体和产物。 自催化作用可能源于（i）吸附到含水锰氧化物（HMO）时提高的底物反应性，（ii）高锰酸盐和较低Mn氧化态（+II、+III、+IV）之间的缩合反应，其提高Mn（V）和Mn（VI）浓度，（iii）高锰酸盐-底物反应，其在表面或溶液中产生新的氧化剂。 试剂探针，以及pH值和主要离子组成的影响的探索将有助于解决可能的机制。 高分辨率透射电子显微镜（HRTEM），结合选择性区域电子衍射（SAED）和电子能量损失谱（EELS），将用于表征锰（氢）氧化物固体高锰酸盐氧化。他们将探索使用毛细管电泳鉴定和定量的中间氧化态锰物种。PI实验室的独特专业知识组合，即无机反应机制，有机反应机制和非均相形态测定，需要解决所提出的科学/技术问题。 通过提高高锰酸盐氧化的效率，并通过阐明高锰酸盐氧化产物的身份和产量，拟议的工作将作出重大贡献的水质领域。PI的实验室已经开发了几个关键的概念和工具，在该地区的金属有机相互作用在水中。 9名女性和5名男性完成了博士学位。在PI实验室的培训，包括8个目前持有终身职位的任命。 PI帮助组织了巴尔的摩罗林斯音乐学院的外展活动，并在音乐学院领导每月的“科学演示”。