Synergistic interaction of sulfonated poly(ether ether ketone) and carboxylated graphene oxide to enhance PMIA nanofiltration membrane performance for desalination

In this research, we prepared PMIA/GO-COOH/SPEEK composite nanofiltration membranes using a one-step phase inversion method. Firstly, carboxylated graphene oxide (GO-COOH) and sulfonated poly(ether ether ketone) (SPEEK) were prepared, and their synergistic interaction was used to modify PMIA nanofiltration membranes. Through cooperative interaction, the pore structure, surface hydrophilicity, and surface negative charge density of the PMIA/GO-COOH/SPEEK composite membrane were all enhanced. It is noteworthy that the membrane's water flux and desalination performance were enhanced significantly, thereby surmounting the trade-off between flux and rejection. The PMIA/GO-COOH/SPEEK (0.3 wt% GO-COOH, 1 wt% SPEEK) composite membrane exhibited a pure water flux of 154.3 (L/m 2 /h) at 0.8 MPa. Furthermore, it achieved a Na 2 SO 4 retention rate of 92.6%, marking a 20% enhancement compared to the retention rate of pure PMIA nanofiltration membranes, which was 75.2%. Moreover, the PMIA/GO-COOH/SPEEK composite membrane displays exceptional long-term stability, attributable to the covalent bond connection between the polymer and the modified materials.