Highly efficient removal of per- and polyfluoroalkyl substances by extrusion-regenerated aminated polyurethane sponges

Per- and polyfluoroalkyl substances (PFAS) are a class of persistent organic compounds widely detected in the environments. Due to their chemical stability, physical adsorption has emerged as one of the most promising techniques for remediating PFAS-containing wastewater, while some newly synthesized functional absorbents in powder form suffer from separation issues. Inspired by mussel biology, we have successfully synthesized a porous spongy absorbent termed aminated polyurethane (PU-PDA-PANI) with over 99.5% removal efficiency for initial 10 mg L-1 perfluorooctanoic acid (PFOA), corresponding to the maximum adsorption capacity of 1.42 g g-1, which was superior to the ion exchange resin (Purolite® PFA694E, 0.764 g g-1). In addition to PFOA, PU-PDA-PANI also showed excellent removal efficiencies for other typical PFAS (i.e. perfluorooctane sulfonates, perfluorobutyric acid, perfluorooctane-1,8-dioic acid, hexafluoropropylene oxide trimer acid, etc), and the adsorption processes resistant to pH changes and co-existing environmental matrixes. Furthermore, PU-PDA-PANI can be readily reused and regenerated by coupling extrusion and elution procedures. The adsorption mechanism of electrostatic, hydrogen bond and hydrophobic synergistic interaction was further proposed with the support of theoretical calculation. In conclusion, this study develops an efficient and recyclable PFAS adsorbent and proposes some new insights for the design of PFAS-selective adsorbents.