CAREER: Transforming the synergistic interactions between pyrogenic carbonaceous matter and sulfur species into solutions for contaminant detoxification

许多卤化污染物以杀虫剂、表面活性剂和工业化学品的形式进入环境。这些有毒污染物通常最终进入湖泊、河流、河口和海洋的沉积物中，以及燃烧产生的空气污染物，如烟尘和称为热源碳质(PCM)的焦炭。PCM可以与一种被称为硫化物的化学物质混合并发生反应，这种化学物质天然存在于许多沉积物中。本项目旨在了解PCM和硫化物之间的相互作用如何自然降解卤化污染物。最终目标是利用这项研究产生的对这些反应的新理解来生产廉价的工程解决方案，这些解决方案将为沉积物中的污染物解毒，并改善人类和生态健康。与这项研究计划相结合的是一个针对服务不足的高中生的教育推广计划，该计划将使用3D虚拟现实模块和动手实验室体验来帮助学生了解污染物是如何进入环境的，以及自然过程如何促进他们的清理。还将编写一本技术丰富和以探究为基础的教学手册，并通过培训讲习班和在线场所分发给教师，以更有效地接触公众。迫切需要制定对生态无害和经济可行的解决方案，以降解环境中的有毒卤化污染物。这些污染物是在现有的受污染场地中发现的，新的卤化污染物继续进入环境。PI最近发表的一项研究表明，PCM和硫化物共同促进了DDT的非生物降解，DDT是一种卤化污染物，释放出毒性较低的产品。这种脱卤化反应代表着一个巨大的未开发的污染物解毒资源，因为PCM和硫化物都天然存在于沉积物中。然而，由于PCM系统在环境中的异质性引起的复杂性，人们不了解脱卤化所需的条件。该项目旨在定义这些条件。该项目的具体目标是：1)通过合成PCM类聚合物作为模型系统，将表面官能度、导电性和孔隙率从PCM的复杂性质中分离出来；2)利用X射线吸收近边结构光谱(XANES)表征依赖PCM形成表面结合硫物种的机制；3)了解表面如何参与脱卤化污染物；以及4)研究环境基质中PCM促进的脱卤化的长期有效性。该项目的结果将改变我们目前对卤化污染物如何在环境中降解的理解，认识到天然丰富的环境试剂的非生物脱卤化能力。使用XANES对相变材料表面形成的硫物种的形态和分布进行深入研究，将有助于发现一种可用于污染物解毒的新的反应途径。此外，通过确定导致其反应性的重要相变材料特性，可以定制新一代碳基材料，以实现对污染物的同时吸附和销毁。这将通过利用这些碳基材料来彻底改变目前的补救做法。最后，该项目将确定容易被相变材料自然分解的化学结构，并向工业提供可持续的化学设计，将对环境的影响降至最低。该项目的教育部分旨在通过纳入创新的教学策略，如开发3D虚拟现实学习模块和采用探究式教学，让具有不同学习风格的学生参与进来。PI每年将提供一个为期四周的项目，名为？水和污染物？让来自费城市中心的高中生参与当前的环境问题和工程解决方案。此外，将在第五年组织教师培训讲习班，以促进更广泛的参与，并帮助将所开发的活动落实到高中课堂。该项目将通过教师培训工作室直接影响大约300名本科生、800名高中生和38名高中教师。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Many halogenated pollutants enter the environment as pesticides, surfactants, and industrial chemicals. These toxic pollutants often end up in the sediment of lakes, rivers, estuaries and the ocean, along with combustion-derived air pollutants like soot and char called pyrogenic carbonaceous matter (PCM). PCM can mix and react with a chemical known as sulfide that naturally exists in many sediments. This project aims to understand how the interaction between PCM and sulfide can degrade halogenated pollutants naturally. The ultimate goal is to use the new understanding of these reactions generated from this research to produce inexpensive engineering solutions that will detoxify pollutants in the sediment and improve human and ecological health. In conjunction with this research initiative will be an educational outreach program targeted at underserved high-school students that will use 3D virtual reality modules and hands-on lab experiences to help students understand how pollutants enter the environment and how natural processes can promote their clean up. A technology-rich and inquiry-based instruction manual will also be developed and distributed to teachers through training workshops and online venues to more efficiently reach the public.There is a pressing need to develop ecologically sound and economically feasible solutions to degrade toxic halogenated pollutants in the environment. These pollutants are found in existing contaminated sites and new halogenated pollutants continue to enter the environment. A recently published study by the PI demonstrates that PCM and sulfide together promote the abiotic degradation of DDT, a halogenated pollutant, which released lower toxicity products. This dehalogenation reaction represents a vast untapped resource for detoxifying pollutants as both PCM and sulfide are naturally occurring in sediment. Yet, due to the complexity that arises from the heterogeneity of the PCM system in the environment, the required conditions for dehalogenation are not understood. This project aims to define these conditions. The specific goals of this project are to: 1) isolate surface functionality, conductivity, and porosity from the complex properties of PCM by synthesizing PCM-like polymers as a model system; 2) characterize the mechanism for the PCM-dependent formation of surface-bound sulfur species using X-ray absorption near-edge structure spectroscopy (XANES); 3) understand how surfaces are involved in dehalogenating contaminants; and 4) investigate the long-term effectiveness of PCM-facilitated dehalogenation in environmental matrices. The results from this project will transform our current understanding of how halogenated pollutants are degraded in the environment by recognizing the abiotic dehalogenation capacities of naturally abundant environmental reagents. An in depth investigation of the speciation and distribution of sulfur species formed on PCM surfaces using XANES will allow for the discovery of a novel reaction pathway that can be harnessed to detoxify pollutants. Moreover, by identifying important PCM properties that are responsible for its reactivity, a new generation of carbon-based materials can be tailored to achieve simultaneous sorption and destruction of pollutants. This will revolutionize current remediation practices by utilizing these carbon-based materials. Lastly, this project will identify the chemical structures that are susceptible to natural breakdown by PCM and inform industry on sustainable chemical designs that minimize environmental impacts. The educational component of this project aims to engage students with diverse learning styles by incorporating innovative instructional strategies, such as developing 3D virtual reality learning modules and employing inquiry-based teaching. The PI will offer a four-week long program each year, entitled ?Water and Pollutants,? to engage high school students from inner city Philadelphia on current environmental issues and engineering solutions. In addition, teacher-training workshops will be organized in the 5th year to promote broader participation and help implement the developed activities into high school classrooms. This project will directly impact approximately 300 undergraduate students, 800 high school students, and 38 high school teachers through the teacher-training workshop.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.