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

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.