Fig. 4: Mechanistic insights into selective PFAS removal.
a Molecular structures for PFOS and PFOA (the colored dots represent the fluorocarbon units at different sites on PFAS). b Representative fluoroamine chain-type structures in QFgel (the colored dots represent the fluorinated sites on the QFgel). High-resolution XPS (c) N 1 s and (d) F 1 s spectra of QFgel and PFAS-preloaded QFgel. e 19F magic-angle spinning (MAS) spectra of QFgel and PFAS-preloaded QFgel (the blue and red shaded peaks are respectively attributed to i-fluorine and (ii–vi)-fluorine, and the color dots in Fig. 4e–g match the ones shown in Fig. 4a, b). 2D 19F-19F nuclear Overhauser effect spectroscopy (NOESY) NMR spectra of (f) PFOS-preloaded QFgel and (g) PFOA-preloaded QFgel at a mixing time of 0.5 s. h Schematic illustration of F···F contacts between F atoms from PFAS and QFgel’s fluorinated interfaces. i Mean square displacement (MSD) curves of PFAS sorption on quaternary ammonium, fluorous, and fluoroamine chains. j Radial distribution function (RDF) of PFAS molecules with quaternary ammonium and fluoroamine chains. k Sorption energies (Ead) for PFAS sorption onto quaternary ammonium, fluorous, and fluoroamine chains. l Independent gradient model based on Hirshfeld partition (IGMH) isosurface maps for PFAS sorption on fluoroamine chains. IGMH scattering plot analysis of δg (reduced density gradient based on Hirshfeld partition) vs Sign(λ2)ρ (product of the sign of the second largest eigenvalue of the electron density Hessian matrix (λ2) and electron density (ρ)) for (m) PFOS, and (n) PFOA sorption on fluoroamine chains. Source data are provided as a Source Data file.
