While non-destructive technologies (e.g., adsorption, ion exchange, and membrane filtration) have been employed in pilot-scale and/or field applications assuming facile utility including technical simplicity and relatively low cost, these separation processes can generate concentrate streams or spent materials enriched with per-and polyfluoroalkyl substances (PFAS) that need further treatment. In contrast, destructive technologies can permanently destroy these compounds and thus support the long-term sustainability of Department of Defense (DoD) installations and reduce current and future environmental liabilities. However, the highly stable C-F bonds render PFAS destruction very challenging for many treatment processes. The objective of this proof-of-concept project is to demonstrate that efficient destruction of PFAS can be achieved using plasmonic catalysts, thus addressing the research need of developing novel energy-efficient destructive technologies for the treatment of PFAS-impacted aqueous matrices.

In this initial project, the project team will investigate reduction of PFAS by hydrated electrons generated via excitation of localized surface plasmon resonance (LSPR) of catalysts containing plasmonic nanostructures and to evaluate PFAS degradation in a novel plasmon-enhanced catalytic ozonation process. The underlying hypothesis is that energy-efficient destruction of PFAS can be achieved utilizing reactive redox species (e.g., hydrated electrons, holes, radicals) that are produced through excitation of LSPR of rationally-designed plasmonic catalysts. To test this hypothesis, the project team will undertake three research tasks:

1. Develop plasmonic photocatalysts for PFAS destruction
2. Obtain data on PFAS degradation kinetics and impacts of operational conditions and water constituents
3. Estimate energy consumption

This interdisciplinary research effort represents a first attempt to develop an innovative plasmon-enhanced catalytic process for cost-effective treatment of PFAS-impacted aqueous matrices. Research results obtained from this project will verify the feasibility of utilizing LSPR of plasmonic nanostructures to generate reactive redox species for efficient PFAS destruction and lay a solid groundwork for further development of integrated oxidation-reduction PFAS treatment processes. If successful, these new catalysts and treatment processes can be employed at DoD remediation sites and/or treatment plants where PFAS impact is a concern. They can also be used for the treatment of concentrate streams generated from other processes. This research effort will also contribute to scientific understanding of how plasmonic catalysts can be designed and applied to address environmental issues. (Anticipated Project Completion - 2023)