Facile fabrication of high-performance membrane with 2D GO nanosheet in membrane skin by PIC-assisted NIPS method for dye/salt separation

The trade-off between membrane permeance and solute rejection is a persistent challenge in membrane filtration, where higher permeance typically compromises rejection performance. To overcome this limitation, we developed a one-step fabrication method for an integrally skinned asymmetric tight ultrafiltration membrane via a polyion complex reaction-assisted non-solvent induced phase separation process (PIC-assisted NIPS). A reactive hydrolyzed polyacrylonitrile (H-PAN) matrix was used to prepare the dope solution, while an aqueous solution of polyethyleneimine (PEI)/graphene oxide (GO) soluble complexes served as the coagulation bath. During phase separation, the PEI/GO complex further participates in polyelectrolyte complexation with H-PAN, resulting in the formation of a dense selective layer composed of HPAN/PEI/GO on membrane surface, enabling simultaneous high permeance and rejection. Subsequent crosslinking with glutaraldehyde further stabilized the membrane structure. The PEI content and molecular weight in the complexes critically influenced the skin layer thickness and separation performance. The optimal membrane, fabricated with 0.4 wt% PEI-10000 in the coagulation bath, exhibited exceptional performance: a water permeance of 226.1 ± 0.4 L·m −2 ·h −1 ·bar −1 , 99.8 ± 0.1 % rejection of Congo Red, and 3.2 ± 0.3 % NaCl rejection. This study presents a facile and efficient strategy for fabricating high-performance tight ultrafiltration membranes for dye removal from wastewater.