Collaborative Research: ECO-CBET: Plasma-Assisted Dehalogenation of Persistent Halogen-Containing Waste Streams

利用含卤化合物的“取-制-弃”模式已经污染了地球的水、土壤和空气资源。由于卤素是强氧化剂而产生的强碳卤素键导致了一个令人生畏的污染挑战。30年前为封堵南极臭氧洞而在全球范围内禁用的氯氟烃（CFCs）仍在大气中存在。此外，目前有超过9000种聚氟烷基和全氟烷基物质（PFAS）污染世界各地的雨水，聚氯乙烯（PVC）塑料占城市垃圾中氯含量的50%以上。今天，外来有机卤素化合物无处不在：2亿美国人饮用受pfas污染的水，聚氯乙烯是美国每年二恶英负担的主要来源，超过了任何其他工业产品。为了解决这一遗留污染挑战，需要一种超越当前热化学技术有限范围的阶跃变化解决方案。在这个项目中，等离子体辅助脱卤被提出作为解决这一挑战的破坏性解决方案。该项目侧重于利用非平衡等离子体降解和回收含卤废物，在改善人类健康和保护环境方面具有巨大潜力。这一融合研究项目将为跨学科STEM教育和培训提供独特的机会，并为学生和研究人员成为下一代跨学科科学家和工程师做好准备。计划中的拓展活动包括为K-12课程开发实践活动，重点关注处于危险中的、经常被低估的学生。这项工作涉及与工业界建立伙伴关系，以进一步发展技术，并开展活动，提高当地社区对普遍存在的含卤化合物及其带来的相关健康和安全挑战的认识。该研究的目标是在机制水平上探索等离子体辅助脱卤反应化学，并利用这些见解开发创新工艺，使反应产物的回收或卤化成分的完全矿化成为可能。非平衡等离子体是指在接近环境温度下工作的部分电离气体，其中只有电子具有足够高的动能，能够产生短寿命的反应物质，这些反应物质作为各种底物链式反应的引发剂。这一融合研究项目利用了PIs在化学反应工程、等离子体科学、化学建模和理论以及环境工程方面的专业知识，建立了一个等离子体脱卤模型，该模型将用于设计一个等离子体辅助废物流脱卤的反应器，重点是PFAS和PVC作为两个测试平台案例。这项研究的成功完成将带来新的基础科学见解和工程解决方案，有助于为各种废物流的脱卤提供更广泛的框架。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。

The “take-make-dispose” model for the utilization of halogen-containing compounds has polluted the planet’s water, soil, and air resources. The strong carbon-halogen bonds resulting from halogens being potent oxidants have resulted in a contamination challenge with a daunting legacy. Chlorofluorocarbons (CFCs), which were globally banned 30 years ago to close the Antarctic ozone hole, persist in the atmosphere. Additionally, there are over 9000 poly- and perfluoroalkyl substances (PFAS) currently contaminating rainwater worldwide, and polyvinylchloride (PVC) plastics account for more than 50% of chlorine found in municipal waste. Today, xenobiotic organohalogen compounds are pervasive: PFAS-contaminated water is consumed by 200 million Americans and PVC is the primary contributor to the nation’s annual dioxin burden, surpassing that of any other industrial product. To address this legacy contamination challenge, a step change solution is required, one that surpasses the limited scope of current thermochemical technologies. In this project, plasma-assisted dehalogenation is proposed as a disruptive solution to this challenge. The project focuses on the use of non-equilibrium plasmas for the degradation and recycling of halogen-containing waste and holds enormous potential for improving human health and preserving the environment. This convergent research project will provide unique opportunities for interdisciplinary STEM education and training and prepare a diverse pipeline of students and researchers to become the next generation of interdisciplinary scientists and engineers. Planned outreach activities involve the development of hands-on activities for K-12 programs, with a focus on at-risk and often underrepresented students. The effort involves partnerships with industry to further technological development and activities that raise awareness among local communities about the pervasive presence of halogen-containing compounds and the associated health and safety challenges they pose.The goal of the research is to probe at a mechanistic level plasma-assisted dehalogenation reaction chemistry and to use these insights to develop innovative processes that make possible recycling of reaction products or the full mineralization of haloginated components. Non-equilibrium plasma refers to a partially ionized gas operating at near ambient temperatures, where only the electrons possess kinetic energies high enough to enable the production of short-lived reactive species which act as initiators for chain reactions of various substrates. This convergent research program leverages the PIs’ expertise in chemical reaction engineering, plasma science, chemical modeling and theory, and environmental engineering to establish a plasma dehalogenation model that will be used to design a reactor for plasma-assisted dehalogenation of waste streams with a focus on PFAS and PVC as two testbed cases. The successful completion of this research will lead to new fundamental scientific insights and engineering solutions contributing to a broader framework for dehalogenating a wide range of waste streams.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.