A novel polysulfone ultrafiltration membrane constructed with the sandwich-like structure SGO-ZnO for ultra-easy water transport and enhanced anti-fouling

•The increased anti-fouling due to the negative charge of the -SO3H group in SGO improves the service life.•Rigid ZnO inhibits stacking and wrinkling of SGO, prolonging the vertical and lateral bending channel between layers.•Sandwich-structured SGO-ZnO nanofillers provide good humic acid separation performance. Fouling formation on membrane surfaces limits membrane-based separation performance in industrial activities such as wastewater recycling and desalination. Designing and preparing emerging materials capable of improving the balance between permeability and rejection remains a great challenge. A sandwich-like composite with loose and flat interlayers was produced by combining rigid zinc oxide (ZnO) nanoparticles with easily stackable, folded sulfonated graphene (SGO) and subsequently non-solvent-induced phase separation (NIPs) was employed to produce novel PSF ultrafiltration (UF) membranes with varying amounts of nanofiller of SGO-ZnO. The successful anchoring of ZnO on SGO was confirmed by FTIR, XRD, Raman spectroscopy and TGA. The produced membranes have been investigated using contact angle (CA), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The incorporation of ZnO suppressed the stacking and wrinkling of SGO, which increased the vertical interlayer paths and lateral bending paths. As a result, water molecules could freely pass through the extended channels of SGO, and with only 0.2 wt% of nanoparticles doped, the pure water flux was increased f from 229.2 L m−2h−1 to 601 L m−2h−1. Negatively charged impurities were selectively repelled due to electrostatic interactions with −SO3H, which resulted in the removal of BSA remaining above 98 %. In addition, the separation performance of the humic acid (HA)-simulated water sample, a common contaminant, was investigated using the designed modified membranes. The greatest HA rejection (98.33 %) was shown by the UF membrane. All these findings suggest that the addition of sandwich-like SGO-ZnO successfully overcomes the “trade-off effect” between permeability and selectivity in PSF membranes.