Synthesis of furan-based cationic biopolyamides and their removal abilities for perfluoroalkyl and polyfluoroalkyl substances

Functional polyamides have attracted much attention among researchers owing to the amide structure is widely found among naturally occurring peptides and proteins. In this study, the novel cationic biopolyamides (C-bioPAs) with excellent biocompatibility are prepared and proposed as removal agents for perfluoroalkyl and polyfluoroalkyl substances (PFAS) from water. Renewable bisfuran-based functional diacid/diamine monomers were employed to prepare a reactive polyamide with tertiary amine pendant groups through polycondensation. Subsequently, the precursor underwent quaternization modification with different alkyl bromides to obtain a series of C-bioPAs. The chemical structure of all newly prepared C-bioPAs was characterized using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The thermal stability of C-bioPAs was assessed by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The C-bioPAs effectively remove PFAS from water, achieving a maximum removal efficiency of 99.8 %, rapid initial sorption rates (>2.964 mmol g -1 h −1 ), and short equilibrium times (<12 h). Attractively, the cationic bioPAs could be recycled and reused over 5 times without significant loss of removal efficiency, suggesting that they have the potential to be a sustainable and effective alternative to traditional cationic PFAS adsorbents.