Thin film composite polyesteramide membrane with the incorporation of rigidly-contorted binaphthol-based monomer for enhanced nanofiltration separation performance

Abstract

High-performance nanofiltration (NF) membranes prepared by interfacial polymerization (IP) are ideal choice for solving water scarcity. In this study, 7,7′-dihydroxy-2,2′-binaphthol (7,7′–OH-BINOL) with rigidly-contorted structure was used as a co-monomer with piperazine (PIP), leading to NF membranes with lower selective layer thickness and enhanced microporosity, thus facilitated the water molecules transportation. The incorporation of 7,7′–OH-BINOL could regulate the interface diffusion rate of PIP and afforded the polyesteramide selective layer with a special bowl-shaped crater surface morphology. The PIP/BINOL-TMC nanofiltration membrane with the optimal phenol/amine ratio presented water permeability of up to 17.01 L m-2 h−1 bar−1, which was more than two times that of the pristine NF membrane (i.e. PIP-TMC). Meanwhile, it displayed comparable Na2SO4 rejection (∼98%) and excellent mono-/divalent salt selectivity (SNaCl/Na2SO4 = 44). In addition, long-term operation and pressure resistance test results demonstrated that the tailored membrane had good operational stability. In conclusion, this work provides a feasible way to overcome the perm-selectivity trade-off effect of NF membrane and potentially could be used to solve the water scarcity problem.