Thin-film composite membranes with aqueous template-induced surface nanostructures for enhanced nanofiltration

Surface morphology has been proven to significantly affect nanofiltration (NF) membrane performance. However, the morphology control in membrane fabrication remains a great challenge. Herein, based on interfacial manipulation, a new strategy was developed to fabricate NF membranes with tunable 3D surface nanostructures. The manipulation was achieved by forming aqueous template on the substrate surface during the membrane fabrication, which directly influenced the consequent membrane surface morphology. Based on this, a systematic transition of surface morphology from leaf-like shapes to ridges was achieved in a facile way. The representative NF membrane with ridged nanostructures exhibited water permeance of 21.3 Lm-2h-1bar-1 and Na2SO4 rejection of 99.4 % due to increased permeable area, reduced membrane thickness and low-resistance flow channel within the ridged nanostructures. The mechanism and detailed process of forming these 3D surface nanostructures were demonstrated by combining dissipative particle dynamics (DPD) simulations and experiments. In consideration of the simplicity, generality and controllability, this aqueous template-based interfacial manipulation strategy would be of importance to the fabrication of thin-film composite membranes.