Effect of poly(2-(dimethylamino)ethyl methacrylate) brush-grafted graphene oxide on polyamide layer formation and nanofiltration performance

Thin film composite (TFC) membrane performance is often restricted by permeability and selectivity trade-off effect, even with the modification of nanoparticles. Graphene oxide-poly(2-(dimethylamino)ethyl methacrylate) (GO-PDMAEMA) with brush structure has abundant hydrophilic oxygen-containing functional groups and amine groups. It was synthesized via the atom transfer radical polymerization method and incorporated into TFC polyamide layer using interfacial polymerization. The GO-PDMAEMA-modified thin film nanocomposite membranes (TFNG-P) with Turing structure and higher surface hydrophilicity enhanced water permeability by 40.7-55%, with relatively low nanoparticle loading (0.005-0.02 wt%). Besides, TFNG-P2 (0.01 wt% GOPDMAEMA) has the highest Na2SO4 rejection (97.8%), 4.4% higher than TFC. The PDMAEMA brushes on GO with additional amine groups promoted the amide linkage and increased the PA layer cross-linking by 16.2%. The higher cross-linking did not negatively affect the membrane flux, as the better hydrophilicity offset this effect. The utilization of the modified membranes in the treatment of palm oil mill effluent demonstrated enhanced resistance to fouling with TFNG-P2, which exhibited the highest flux recovery rate, reaching 89.4%. Thus, this study showed GO modification by grafting PDMAEMA brushes had enhanced the membrane properties, resulting in TFNG-P with higher permeability, promising separation and antifouling performance.