Simple, Green Pathway to Precipitate Perfluorooctanoate (PFOA) via Transformation to an Insoluble Ester

Perfluorooctanoic acid (PFOA) is a PFAS compound of significant concern due to its persistence and adverse health effects. Effective treatment techniques for highly concentrated PFOA solutions are needed to curb elevated emissions from industrial fluorochemical manufacturing sites among other treatment/waste streams. Herein, we report that in the presence of decanol alone, PFOA readily transforms into a stable fluorinated ester (decylpentadecafluorooctanoate), which precipitates out of solution due to a significant decrease in solubility. The mixture of PFOA and decanol, without additional surfactant, is sufficient for formation of nonaqueous phase emulsions wherein esterification proceeds at 90% yield near room temperature. Reaction kinetics, mass balance, and products are detailed, via FTIR and ¹⁹F qNMR, for a range of conditions. Taken together, this reaction opens a potential new treatment paradigm for concentrated, carboxylic-based PFAS, via a low-energy, green chemistry-based approach.