Impact of dissolved organic matter on phenolic contaminant oxidation by manganese oxides

锰（Mn）氧化物是在土壤中发现的天然矿物质，在将有毒的水生污染物转化为不那么危险的副产品方面显示出很大的希望。然而，天然溶解有机物（DOM）可能会极大地限制这种转化能力。鉴于天然水体中存在DOM，必须了解DOM的影响，才能进一步开发锰氧化物作为一种处理技术。这个研究项目将通过使用最先进的化学分析技术详细分析DOM存在下的污染物转化来解决这个问题。这项研究的成功完成将有助于评估基于氧化锰的污染水修复的可行性，并指导提高该过程效率的努力。在研究中支持女性和未被充分代表的少数民族，从而扩大美国STEM劳动力的多样性，这将给社会带来额外的好处。对K-12学生的额外教育推广将增加对环境污染的了解，并提高国家的科学素养。锰（Mn）氧化物是普遍存在的强氧化剂，能够与无机和有机污染物发生反应。目前正在探索在工程系统和污染水的原位处理中使用天然或合成锰氧化物。然而，对有机污染物如何与锰氧化物相互作用的基本理解还处于起步阶段。溶解有机物（DOM）在自然环境中的普遍存在增加了确定锰氧化物降解有机污染物的速率和机制的复杂性。DOM不仅可以吸附锰氧化物并与之反应，还可以稳定溶解的有机和无机反应产物。先前的研究表明，DOM可能因此增加、减少或不影响锰氧化物对酚类污染物的降解。需要更好地了解这些相互作用才能将锰氧化物用于水处理。因此，拟议项目的总体目标是确定在设计用于氧化污染物的工程系统中控制DOM， Mn氧化物和酚醛污染物相互作用的关键机制。这一目标将通过以下研究目标来实现：1)使用六个模型DOM分离物和三个完整的水来表征DOM与Mn氧化物的相互作用，这些水覆盖了广泛的DOM组成；2)采用6种不同限速步骤的酚类污染物，评估DOM对锰氧化物转化有机污染物的影响。总之，这种结合表面和水化学的新方法将有助于理解DOM改变污染物转化速率的机制以及DOM、锰氧化物和酚类污染物之间的相互作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Manganese (Mn) oxides are naturally occurring minerals found in soil that have shown great promise to transform toxic waterborne contaminants less hazardous byproducts. However, natural dissolved organic matter (DOM) may dramatically limit this transformation capacity. Given that DOM is present in natural waters, the impacts of DOM must be understood to further develop Mn oxides as a treatment technology. This research project will address this issue through detailed analysis of contaminant transformation in the presence of DOM using state-of-the-science chemical analysis. Successful completion of this research will allow assessing the feasibility of Mn oxide-based remediation of contaminated water and guide efforts to increase the efficiency of the process. Additional benefits to society will come from supporting women and underrepresented minorities in the research, thus broadening the diversity of the Nation’s STEM workforce. Additional educational outreach to K-12 students will increase understanding of environmental pollution and increase the Nation’s scientific literacy. Manganese (Mn) oxides are ubiquitous, strong oxidants capable of reacting with inorganic and organic contaminants. The use of natural or synthetic Mn oxides in engineered systems and for in situ treatment of contaminated waters is currently being explored. However, a fundamental understanding of how organic contaminants interact with Mn oxides is in its infancy. The ubiquitous nature of dissolved organic matter (DOM) in natural environments adds to the complexity of determining the rates and mechanisms of organic contaminant degradation by Mn oxides. Not only does DOM sorb and react with Mn oxides, it also may stabilize dissolved organic and inorganic reaction products. Previous work indicates that DOM may therefore increase, decrease, or have no effect on phenolic contaminant degradation by Mn oxides. A better understanding of these interactions is needed to apply Mn oxides for water treatment. Thus, the overall goal of the proposed project is to identify the key mechanisms that govern the interactions of DOM, Mn oxides, and phenolic contaminants in engineered systems designed to oxidize contaminants. This goal will be achieved through the following research objectives to: 1) characterize the interactions of DOM with Mn oxides using six model DOM isolates and three whole waters that cover a wide range of DOM composition; and 2) assess the impact of DOM on organic contaminant transformation by Mn oxides using six phenolic contaminants that have different rate-limiting steps. Together, this novel approach combining surface and aqueous chemistry will facilitate understanding the mechanisms by which DOM alters contaminant transformation rates and the interactions between DOM, Mn oxides, and phenolic contaminants.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.