Fluorine-free cationic pillar[5]arene polymers for efficient PFAS capture

Due to their extensive use and widespread distribution, per - and polyfluoroalkyl substances (PFAS) pose significant risks human health and the environment. Development of efficient and environmentally benign adsorbents is urgently needed. In this study, three fluorine-free polymers (labeled QA2P-P , QA4P-P , and QA6P-P ) with cationic binding sites were constructed from quaternized pillar[5]arenes conveniently. These polymers exhibited excellent removal performance for three representative PFAS (perfluorooctanoic acid [PFOA], perfluoropentanoic acid [PFPeA], and ammonium perfluoro-2-propoxypropionate [GenX]). Notably, QA2P-P exhibited >99% removal efficiency for PFOA and GenX. Furthermore, QA2P-P reduced PFOA and GenX from 1 μg L −1 to <4 and < 10 ng L −1 , respectively. The maximum adsorption capacity of QA2P-P was 868.9 mg g −1 for PFOA, 399.6 mg g −1 for GenX, and 452.1 mg g −1 for PFPeA. These results positioned QA2P-P ahead of all previously reported fluorine-free materials and make it comparable to outstanding fluorinated adsorbents. Electrostatic and hydrophobic interactions worked together to enhance the removal capacity. All the polymers were easily synthesized, stable, and readily regenerated. The present research provided valuable guidance for the design of fluorine-free and efficient adsorbents for PFAS.