Spin-spray assisted layer-by-layer assembly of polyelectrolyte multilayer nanofiltration membranes with competitive organic fouling resistance

Spin-assisted Layer-by-Layer (LbL) assembly is a fast method for constructing multilayered membranes, but it faces challenges when applied to larger polymeric support surfaces due to inconsistent layering quality. To address these limitations, a combined spin-spray assisted LbL technique was utilized for membrane fabrication. In this study, nanofiltration thin-film composite membranes were produced by alternately depositing branched-polyethyleneimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) onto polyethersulfone (PES) ultrafiltration membrane supports. These membranes were tested for their ability to separate NaCl from water. One of the membranes, with a (PEI/PSS) 10 structure, demonstrated a rejection rate of 76.2 % and a permeability of 2.79 L/h·m²·bar under testing conditions of 10 bar pressure, a temperature of 24.58 ± 0.51 °C, and a NaCl feed concentration of 2076.75 ± 40.51 ppm. The fouling resistance of the membrane was also evaluated over a 5-day period, showing stable performance with only a 30 % flux reduction due to fouling, which is comparable to commercial nanofiltration membranes such as NF90. This work highlights the potential of the spin-spray assisted LbL technique as a promising and flexible method for membrane fabrication, suitable for a wide range of materials and scalable for industrial applications.