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(PFAS)是已在各种工业中使用的人造化学品。PFAS具有出众的稳定性、拒油和拒水能力，以及其他宝贵的特性，使其在消费产品、电子制造和消防应用中得到全球分布。然而，排放和处置不当，再加上环境的持续性，导致饮用水水源普遍受到全氟化肥的污染。目前，吸附、离子交换和膜过滤是大规模处理水中PFASs最常用的技术。然而，这些处理方法不会破坏全氟辛烷磺酸化合物，由于需要频繁地再生耗尽的介质和昂贵的浓缩废流处理，因此阻止了它们的更广泛采用。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，以有效地将全氟辛烷磺酸降解为环境友好的产品。这一目标将通过对活性物种的产生和控制及其PFAS反应机理进行一系列实验和动力学模拟来实现。该项目的成功完成将产生知识，为自来水公司和工业排放者开发高效、成本效益高和可持续的PFAS处理技术，以保护公众健康。结果将通过学术出版物传播，以增进知识。其他社会利益包括通过外展、招聘和培训代表不足的K-12、本科生和研究生来加强和多样化国家的STEM劳动力。该项目的目标是发展潜在高效但知之甚少的真空紫外光(VUV)驱动的光化学过程的基础知识，用于治疗PFASs。真空紫外光是一种清洁和节能的介质，可以直接光解水生成HO·、H·和EAQ-等高能自由基。目前，真空紫外光系统用于PFAS处理的应用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，研究将集中于开发一种具有可调节氧化还原环境的VUV系统，以促进全氟辛烷磺酸的降解和矿化。为实现这一目标而设计的具体研究目标将：i)表征真空紫外光照射下的自由基光化学，并检查初级自由基与PFAS的反应性；ii)调查电子供体和接受电子的溶质在调节PFAS处理过程中瞬时反应物种的形态和反应体系的氧化还原极性方面的作用；iii)开发基于一整套基本反应和相关速率常数的综合动力学模型，以确定主导反应并预测环境相关条件下PFAS的降解。研究将使用先进的科学状态高分辨率质谱分析工具来评估全氟辛烷磺酸的转化产物，并推断其在调制水光解过程中的反应路径。这项研究的成功完成将建立必要的科学，以满足国家对有效、低成本的PFAS处理技术的迫切需求。更多的社会效益来自于多个组成部分的教育和外展努力：i)通过研讨会、实验室访问和培训，让K-12学生和教师参与环境化学和工程；ii)让来自代表性不足群体的社区大学生参与研究；以及iii)招募本科生参加研究和指导计划。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。

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.