Mineralization of Captured Per- and Polyfluoroalkyl Substances (PFAS) at Zero Net Cost Using Flash Joule Heating

Per- and polyfluorinated alkyl substances (PFAS) are persistent and widespread environmental contaminants that have infiltrated freshwater systems. Granular activated carbon (GAC), the most widely used sorbent for PFAS removal from water, becomes a secondary waste when PFAS is sorbed upon it (PFAS-GAC). Current methods for treatment of this contaminated spent carbon, such as incineration, release large amounts of hazardous gaseous fluorocarbons. To address these challenges, here we demonstrate the disposal of PFAS-GAC using an electrothermal mineralization process. Flash Joule heating (FJH) of PFAS-GAC in the presence of sodium or calcium salts yields inert, non-toxic fluoride salts with >96% fluorine conversion efficiency. Simultaneously, the spent carbon is upcycled into high-value flash graphene, offsetting the cost of treatment by $1900 US per tonne. The entire process operates without the need for solvents or expensive catalysts. The life cycle assessment (LCA) shows a reduction in cumulative energy consumption, greenhouse gas emissions, and water usage. The ease of scalability and the production of valuable co-products, as highlighted in the technoeconomic assessment (TEA), showcases this method as an attractive route to mineralize PFAS in ~1 s.