Hydrogel-regulated interfacial polymerization: A gateway to effective nanostructure tuning of polyamide nanofiltration membranes

Controllable interfacial polymerization (IP) is eminently desirable for the preparation of high-performance nanofiltration (NF) membranes to address the worldwide water scarcity. Herein, we report a facile and versatile approach to prepare novel polyamide (PA) NF membranes via a hydrogel-assisted IP process. The piperazine (PIP) diffusion was precisely controlled by tailoring the viscosity of the introduced chitosan/polyvinyl alcohol (CS/PVA) hydrogel via adjusting the hydrogel composition and crosslinking degree. Due to the synergistic effect of the decreased thickness and improved surface hydrophilicity of the PA layer formed atop hydrogel, the hydrogel-regulated thin film composite (TFC-hg) membrane exhibited a high water permeance of 15.5 L m−2 h−1 bar−1, which was 2.5 times of that of the control membrane. Meanwhile, the TFC-hg membrane achieved a Na2SO4 rejection of 99.1 % due to the highly cross-linked PA separation film. This work offers a simple and highly effective strategy for constructing high-performance TFC NF membranes toward efficient water treatment.