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

利用含卤素化合物的“采取-制造-处置”模式已经污染了地球上的水、土壤和空气资源。由于卤素是强有力的氧化剂，产生了强烈的碳-卤键，导致了一项令人望而生畏的污染挑战。氯氟烃(CFCs)30年前在全球范围内被禁止，目的是关闭南极的臭氧层空洞，但这种物质仍然存在于大气中。此外，目前全球有9000多种聚氟烷基物质(PFA)污染雨水，聚氯乙烯(PVC)塑料占城市垃圾中发现的氯的50%以上。今天，异类有机卤化物无处不在：2亿美国人使用被全氟辛烷磺酸污染的水，聚氯乙烯是美国每年二恶英负担的主要贡献者，超过任何其他工业产品。为了解决这一遗留的污染挑战，需要一种超越当前热化学技术有限范围的阶段性改变解决方案。在这个项目中，等离子体辅助脱卤化被提出作为对这一挑战的破坏性解决方案。该项目的重点是利用非平衡等离子体降解和回收含卤素废物，在改善人类健康和保护环境方面具有巨大潜力。这一融合的研究项目将为跨学科STEM教育和培训提供独特的机会，并为成为下一代跨学科科学家和工程师培养多样化的学生和研究人员。计划的外展活动包括为K-12课程开发实践活动，重点是高危和经常代表不足的学生。这项工作涉及与工业界的伙伴关系，以促进技术开发和活动，以提高当地社区对普遍存在的含卤素化合物及其带来的健康和安全挑战的认识。研究的目标是在机械水平上探索等离子体辅助脱卤化反应化学，并利用这些见解开发创新的工艺，使反应产物的回收或卤化组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，只有电子具有足够高的动能，才能产生短暂的反应物种，作为各种底物连锁反应的引发剂。这一融合研究计划利用PI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化模型，该模型将用于设计一个用于废气等离子体辅助脱卤化的反应器，重点是PFAS和PVC作为两个试验台案例。这项研究的成功完成将带来新的基础性科学见解和工程解决方案，有助于建立一个更广泛的框架来脱卤化广泛的废流。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。

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.