Enzymatic PFAS destruction coupled with lanthanum fluoride recovery

Per- and polyfluoroalkyl substances (PFAS) must be treated in large volumes to reach nanogram-per-litre regulatory limits, yet destructive technologies remain confined to the laboratory, while separation methods only concentrate the problem into hazardous waste. This study integrates three functions, enzymatic C-F bond cleavage, fluoride capture by Lewis-acidic metal-organic frameworks, and capacitive electro-swing regeneration, into a single hierarchical architecture that acts as a continuous PFAS-to-fluoride converter. Trametes versicolor laccase and its ABTS mediator are co-immobilised within mesoporous PCN-333(Al) nanocrystals grown on carbon nanotube scaffolds; sub-6 nm confinement drives substantial electric double-layer overlap, unifying biocatalysis and selective ion capture in one electrostatic field. A mild capacitive swing potential (-1.0 V) gates the capture and release of fluoride while sustaining oxidative cleavage of perfluorooctanoic acid (PFOA). The system removes more than 95% of PFOA from contaminated groundwater at a fluoride-to-chloride selectivity above 140:1, sustains this across 2500 cumulative hours with 89 ± 3% of enzyme activity retained, and mineralises 98.7% of the fluorine, recovering 94 to 97% as high-purity lanthanum fluoride (LaF₃). Treatment costs approximately $1.18 m^-3 at 1.17 kWh m^-3, about 7 to 15 times lower than those of oxidative and thermal destruction methods, establishing a resource-valorising route that converts a persistent pollutant into a critical-mineral precursor.