(186g) Complete Electrocatalytic Aqueous Defluorination of Perfluorooctane Sulfonate with Nonprecious Materials

Per- and polyfluoroalkyl substances (PFAS), a category of robust synthetic chemicals extensively utilized in various consumer, commercial, and industrial products, have led to widespread contamination of water, soil, and living organisms on a global scale. Due to concerns regarding their persistence and toxicity, the urgency for advanced remediation strategies has become evident. Our assessment of existing PFAS destruction techniques highlighted their high costs and energy consumption, emphasizing the necessity for globally scalable technologies. These technologies must utilize nonprecious materials, operate efficiently in aqueous media with low energy consumption, and ensure complete PFAS destruction.¹

We have devised a scalable and economically viable solution employing electrocatalysis and ultraviolet light for the complete mineralization of perfluorooctane sulfonate (PFOS) in aqueous electrolytes, even at environmentally relevant low concentrations of 27 ppm.² Our approach utilizes nonprecious nanocatalysts prepared by pulsed laser in liquids synthesis,³ allowing for controlled surface chemistries and a quantitative understanding of electrocatalytic processes, particularly within the electrode microenvironment. Laser-made nanosheets of [NiFe]-layered double hydroxide were immobilized on hydrophilic carbon fiber paper anodes,⁴ enabling complete defluorination of PFOS in aqueous alkali hydroxide electrolyte. The defluorination process occurred within the anode microenvironment, as evidenced by electrolyte agitation experiments, pulsed electrolysis vs continuous chronoamperometry data, and XPS data. Importantly, our method relies solely on nonprecious materials, being nearly a hundred times cheaper than using boron-doped diamond electrodes, which enables addressing environmental issues and promoting social justice on a global scale. Through systematic variation of electrocatalysis process parameters, we gained mechanistic insights into the aqueous defluorination of PFOS.²

References:

(1) Wilsey, Taseska, Meng, Yu, Müller, Chem. Commun. 2023, 59, 11895-11922.

(2) Meng, Wilsey, Cox, Müller, J. Catal. 2024, 431, DOI: 10.1016/j.jcat.2024.115403.

(3) Forsythe, Cox, Wilsey, Müller, Chem. Rev. 2021, 121, 7568-7637.

(4) Wilsey, Watson, Fasusi, Yegela, Cox, Raffaelle, Cai, Müller, Adv. Mater. Interfaces 2023, 10, 2201684.