Synergistic effect of POSS and chitosan on highly enhancing the separation selectivity and antifouling capacity of polyamide membranes

The trade-off limit between permeability and selectivity , along with membrane fouling , has consistently posed significant challenges impeding the practical implementation of water purification membranes. In this paper, a combination of polyhedral oligomeric silsesquioxanes (POSS) and chitosan is introduced into the polyamide layer through interfacial polymerization and crosslinking to optimize the physical, chemical structure of membrane simultaneously. The resulting P/CS-2-POSS-2 membrane exhibits a notable water flux of 221.3 L m −2  h −1  MPa −1 and a substantial Na 2 SO 4 rejection of 97.1 %. The selectivity of water molecules over sulfates in the optimized hybrid membrane is approximately 4 times greater than that observed in the pristine polyamide membrane. This finding underscores the success of the developed method in mitigating the trade-off between permeability and selectivity. Furthermore, the hybrid membranes exhibit superior antifouling properties, as evidenced by an impressive flux recovery ratio of 95.8 % for bovine serum albumin. Additionally, the mass transport properties of the prepared membranes are explored via molecular dynamics (MD) simulations. The results highlight that chitosan primarily enhances the membrane's hydrophilicity , whereas POSS predominantly regulates the membrane's pore size. Both fillers synergistically enhance the comprehensive performance of the membrane by effectively utilizing steric hindrance and the Donnan effect .