(Invited) Electrocatalysis for Complete Aqueous Defluorination of Perfluorooctane Sulfonate
Authors: Mueller Astrid M 
Published: December 2024

Per- and polyfluoroalkyl substances (PFAS), a group of durable synthetic chemicals widely used in consumer, commercial, and industrial products, have caused global contamination of water, soil, and organisms. Concerns about their persistence and toxicity necessitate advanced remediation strategies. We assessed existing PFAS destruction techniques, emphasizing their limitations such as high costs and energy consumption, and highlighting the need for globally scalable, viable technologies that use nonprecious materials, operate in aqueous media with low energy consumption, and ensure complete PFAS destruction.1

We developed a scalable and economically viable solution using electrocatalysis and ultraviolet light illumination for the mineralization of perfluorooctane sulfonate (PFOS) in aqueous electrolytes with PFOS concentrations as low as 27 ppm, which are environmentally relevant.2 In our approach, we employed pulsed laser in liquids synthesis for the development of nanocatalysts with controlled surface chemistries,3 to facilitate a quantitative mechanistic understanding of electrocatalytic processes, particularly within the electrode microenvironment. Nanosheets of [NiFe]-layered double hydroxide made by pulsed laser in liquid synthesis3,4 were immobilized on hydrophilic carbon fiber paper5 anodes, allowing us to achieve complete defluorination of PFOS in aqueous alkali hydroxide electrolyte.2 Defluorination occurred within the anode microenvironment, as evidenced by pulsed electrolysis vs continuous chronoamperometry data, electrolyte agitation experiments, and XPS data. Importantly, our novel approach uses solely nonprecious materials, and we filed a worldwide patent application for our innovation. Systematic variation of electrocatalysis process parameters provided mechanistic insights into the aqueous defluorination of PFOS.

PFAS contamination poses serious threats to humans, ecosystems, water sources, and wildlife. Our newly developed efficient defluorination method is nearly one hundred times cheaper than using boron-doped diamond electrodes and will aid in the remediation of contaminated environments, poised to mitigate the long-term impact of PFAS on aquatic ecosystems, soil quality, and biodiversity. Additionally, lower-income regions globally typically face increased pollution, making electrocatalytic PFAS remediation ideal for decentralized implementation with solar panel-generated electricity, restoring social justice worldwide.2

References:

(1) Wilsey, M. K.; Taseska, T.; Meng, Z.; Yu, W.; Müller, A. M. Advanced Electrocatalytic Redox Processes for Environmental Remediation of Halogenated Organic Water Pollutants. Chem. Commun.
2023,
59, 11895-11922.

(2) Meng, Z.; Wilsey, M. K.; Cox, C. P.; Müller, A. M. Complete electrocatalytic defluorination of perfluorooctane sulfonate in aqueous solution with nonprecious materials. J. Catal.
2024,
431, DOI: 10.1016/j.jcat.2024.115403.

(3) Forsythe, R. C.; Cox, C. P.; Wilsey, M. K.; Müller, A. M. Pulsed Laser in Liquids Made Nanomaterials for Catalysis. Chem. Rev.
2021,
121, 7568-7637.

(4) Hunter, B. M.; Blakemore, J. D.; Deimund, M.; Gray, H. B.; Winkler, J. R.; Müller, A. M. Highly Active Mixed-Metal Nanosheet Water Oxidation Catalysts Made by Pulsed-Laser Ablation in Liquids. J. Am. Chem. Soc.
2014,
136, 13118-13121.

(5) Wilsey, M. K.; Watson, K. R.; Fasusi, O. C.; Yegela, B. P.; Cox, C. P.; Raffaelle, P. R.; Cai, L.; Müller, A. M. Selective Hydroxylation of Carbon Fiber Paper for Long-Lasting Hydrophilicity by a Green Chemistry Process. Adv. Mater. Interfaces
2023,
10, 2201684.