Fig. 4: Nanofiltration performance and separation mechanism.

a Water permeance and PFAS rejections of TbBa-azo and TbPa membranes. b Separation selectivity of TbBa-azo membrane for binary mixtures of pharmaceuticals and inorganic salts. c ermselectivity comparison of TbBa-azo membrane with state-of-the-art membranes for pharmaceutical/NaCl separation. Data for reference membranes are taken from previously reported studies (detailed information is provided in Supplementary Table 1). d Electron density difference map on X–Y plane between the CRO molecule and heteroatoms in TbBa-azo. Red and blue regions represent the increased and decreased electron density, respectively. e IGM scatter plot of CRO interactions with heteroatoms in TbBa-azo and TbPa, and visualization of the interactions (bottom inset: green isosurface denotes regions of intermolecular interaction). f Schematic diagram of the pharmaceutical/salt separation mechanism governed by the coupling of electrostatic repulsion and size exclusion effects in TbBa-azo membrane. g MD simulation box used to simulate the transport of CRO and NaCl through TbBa-azo membrane. h Visualization of the transport trajectories of Na⁺, Cl⁻, and CRO during the MD simulations. i PMF profiles of Na⁺, Cl⁻, and CRO transported through the TbBa-azo membrane. All data in (a, b) represent two independent measurements (n = 2) and error bars indicate variability between measurements. For ball-and-stick model colors in (d, e, and g): C (grey), S (yellow), N (blue), H (white), Na (brown), Cl (green), and O (red).