ERASE-PFAS: Tunable Vacuum-Ultraviolet Irradiation Systems with Highly Polarized Redox Environment for Treatment of Per- and Polyfluoroalkyl Substances

全氟烷基和多氟烷基物质（PFASs）是用于各种工业的人造化学品。全氟辛烷磺酸具有优异的稳定性、拒油拒水能力，以及其他有价值的特性，这些特性使其在全球消费品、电子制造和消防应用中得到广泛应用。然而，排放和处置不当，加上环境的持久性，导致饮用水源普遍受到全氟辛烷磺酸污染。目前，吸附法、离子交换法和膜过滤法是大规模处理水中全氟辛烷磺酸最常用的技术。然而，这些处理方法不会破坏PFAS化合物，由于需要经常再生耗尽的介质和处理高浓度废物流的昂贵费用，因此阻碍了它们更广泛的采用。该项目的目标是通过开发先进的紫外线（UV）光驱动反应工艺来解决这些限制，从而有效地将PFASs降解为环保产品。这一目标将通过一系列的实验和动力学建模的产生和控制的反应物种及其PFAS反应机制来实现。成功完成这一项目将产生知识，为自来水公司和工业排放者开发高效、具有成本效益和可持续的全氟化砷处理技术，以保护公众健康。研究结果将通过学术出版物传播，以促进知识的发展。其他社会效益包括通过拓展、招聘和培训代表性不足的K-12、本科生和研究生，加强和多样化美国的STEM劳动力。该项目的目标是开发一种潜在高效但鲜为人知的真空紫外光（VUV）驱动的光化学过程的基础知识，用于处理全氟烷烃。VUV光是一种清洁和节能的介质，它直接光分解水，产生HO·、H·和eaq-等高能自由基。VUV系统在PFAS处理中的应用目前受到低极化氧化还原环境和所需自由基的低量子产率的限制。为了克服这些不足，研究将重点开发具有可调氧化还原环境的VUV系统，以增强全氟磺酸的降解和矿化。为实现这一目标而设计的具体研究目标将包括：1)表征VUV照射下的自由基光化学特征，并检测初级自由基与PFASs的反应性；ii)研究供电子溶质和接受电子溶质在调节PFAS处理反应体系的瞬态反应物质形态和氧化还原极性方面的作用；iii)建立基于完整的基本反应和相关速率常数的综合动力学模型，以确定优势反应并预测PFAS在环境相关条件下的降解。研究将采用先进的高分辨率质谱分析工具来评估PFASs的转化产物，并推断其在调制水光解过程中的反应途径。这项研究的成功完成将为解决国家对有效、低成本的PFAS处理技术的迫切需求奠定必要的科学基础。额外的社会效益来自多方面的教育和推广工作：i)通过研讨会，实验室参观和培训，使K-12学生和教师参与环境化学和工程；Ii)让来自弱势群体的社区大学生参与研究；iii)招募本科生参加研究和指导计划。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。

Per- and polyfluoroalkyl substances (PFASs) are manufactured chemicals that have been used in a variety of industries. PFASs possess exceptional stability, oil- and water-repelling capabilities, and other valuable properties that have resulted in their global distribution in consumer products, electronic manufacturing, and firefighting applications. However, emissions and improper disposal, coupled with environmental persistence, have resulted in widespread PFAS contamination of drinking water sources. Currently, adsorption, ion exchange, and membrane filtration are among the most used technologies for large scale treatment of PFASs in water. However, these treatment approaches do not destroy the PFAS compounds, preventing their more widespread adoption due to the need for frequent regeneration of exhausted media and costly disposal of concentrated waste streams. The goal of this project is to address these limitations through the development of advanced ultraviolet (UV) light-driven reaction processes to effectively degrade PFASs into environmentally benign products. This goal will be achieved through a series of experiments and kinetic modelling of the generation and control of reactive species and their PFAS reaction mechanisms. Successful completion of this project will generate knowledge to develop efficient, cost-effective, and sustainable PFAS treatment technologies for water utilities and industry dischargers to protect public health. Results will be disseminated through scholarly publication to advance knowledge. Additional societal benefits include strengthening and diversifying the Nation’s STEM workforce through outreach, recruitment, and training of underrepresented K-12, undergraduate, and graduate students.The goal of this project is to develop fundamental knowledge of a potentially highly effective but poorly understood vacuum UV light (VUV)-driven photochemical process for the treatment of PFASs. VUV light is a clean and energy-efficient medium that directly photolyzes water to create energetic radicals such as HO·, H· and eaq-. Application of VUV systems for PFAS treatment is currently limited by the low polarized redox environment and low quantum yield of desired radicals. To overcome these deficiencies, research will focus on developing a VUV system with a modulable redox environment to enhance degradation and mineralization of PFASs. Specific research objectives designed to achieve this goal will: i) characterize radical photochemistry under VUV irradiation and examine the reactivity of primary radicals with PFASs; ii) investigate the roles of electron-donating and -accepting solutes on tuning the speciation of transient reactive species and redox polarity of reaction systems for PFAS treatment; and iii) develop a comprehensive kinetic model based on a complete set of elementary reactions and associated rate constants to identify the dominant reactions and predict PFAS degradation under environmentally-relevant conditions. Research will employ advanced state-of-the-science high resolution mass spectrometric analytical tools to assess transformation products of PFASs and infer their reaction pathways during modulated water photolysis. Successful completion of this research will build the science necessary to address the urgent national need for effective, low cost PFAS treatment technologies. Additional societal benefits result from a multi-component educational and outreach effort to: i) engage K-12 students and teachers in environmental chemistry and engineering through seminars, lab visits, and training; ii) involve community college students from underrepresented groups in research; and iii) recruit undergraduate students to participate in a research and mentoring program.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.