Alicyclic polyamide nanofilms with an asymmetric structure for Cl<sup>−</sup>/<scp>SO<sub>4</sub><sup>2</sup></scp><sup>−</sup> separation
Bingbing Yuan, Shanshan Zhang, Chi Jiang, Ping Hu, Jiabao Cui, Siheng Zhao, Ning Wang, Q. Jason Niu
Abstract
Abstract Herein, we report an asymmetric alicyclic polyamide nanofilm with an enhanced pore interconnectivity established by manipulating the molecular geometric structure, composed of a porous aromatic polyamide dendrimer layer and a dense alicyclic polyamide layer with hollow stripes. The experimental and simulated data demonstrate that the alicyclic polyamide nanofilm with an asymmetric structure exhibits a negative surface charge and contains more interconnected voids ranging from 1.95 to 3.0 Å, which facilitates the rejection of SO 4 2− with a higher charge density and the passage of Cl − with a smaller hydrated radius, resulting in a good Cl − /SO 4 2− separation selectivity. The resulting membrane attains a 197.11 separation selectivity for Cl − and SO 4 2− and a water flux (for Na 2 SO 4 ) ~2.2 times that of the pristine polyamide membrane. This fine‐tuning pore approach resulting from the considered alicyclic structure can also be employed in other separation membranes, such as membranes for gas, solvent, or neutral molecular separation.