This proof-of-concept project is focused on developing a direct electrochemical reduction approach to destroy adsorbed per- and polyfluoroalkyl substances (PFAS) within granular activated carbon (GAC), enabling in situ regeneration of the spent GAC materials. This one-year project has three specific objectives, including (1) direct electrochemical reduction of adsorbed-PFAS in polar aprotic organic solvents, (2) quantitative PFAS analysis to characterize end products and electrochemical degradation pathways, and (3) preliminary techno-economic assessment to evaluate the viability of the electrochemical approach against existing thermal-based GAC management.

This aim of this project is to develop a direct electrochemical reduction (DER) technique to destroy adsorbed PFAS using polar aprotic organic (PAO) solvent matrices, promoting in situ regeneration of spent GAC at room temperature. The fundamental principles of DER in organic solvents have demonstrated successful transformation of less refractory organic pollutants. Building upon this foundation, organic reductive electrochemistry will be tailored specifically for PFAS destruction. 

The overarching hypotheses driving this project are as follows: 

• The use of electrochemically stable PAO solvents, as opposed to water, can sustain a more negative reduction potential on GAC.
• A much lower reduction potential can facilitate direct electron transfer to break the C-F bonds and effectively destroy adsorbed PFAS within the GAC.
• The relative volatile nature of organic solvents ensures easy separation after DER, facilitating on-site GAC reuse in field operations. 

The technical approach involves screening electrochemically stable PAO solvents such as acetonitrile and methanol, exploring reductive PFAS thermodynamics, tailoring transformation kinetics, and performing a technoeconomic assessment.

This project aims to provide fundamental insights into the PFAS degradation mechanisms in non-thermal physicochemical treatment processes. The proof-of-concept findings will serve as a foundation for developing an electrochemical PFAS destruction technique, offering benefits such as efficient handling of PFAS-impacted matrices, including reduced dependence on transportation and ex situ waste disposal. Results from the research may ultimately lead to expedited cleanup and closure of PFAS-impacted sites, thereby directly fortifying the Department of Defense's operational capabilities and securing warfighter preparedness. (Anticipated Project Completion - 2026)