Nanorod-interlayered thin film composite membranes for ultrafast nanofiltration

Customizing high-performance nanofiltration membranes that can break the trade-off effect is critical to the development of membrane separation. Building an intermediate layer between the support and the selective layer to accelerate water transport is considered to be an effective solution to this issue. However, the synthesis of interlayered thin-film composite membranes (i-TFCs) on non-polar substrates with large pores and high porosity remains challenging. Here, we report a high-performance i-TFC membrane with FeOOH nanorods as interlayers. The porous and robust nanorods greatly increased the water transport paths and the mechanical strength of the membrane. Under the high pressure of 20 bar, the i-TFC membrane still remained a high salt rejection above 96 % while showing a high pure water permeance up to 48.9 L·m−2·h−1·bar−1. Furthermore, the presence of nanorods enhanced the hydrophilicity and compactness of the substrate, leading to the formation of a 23-nm thick polyamide layer without nanorod structures. The versatility of the strategy was also demonstrated with three different hydrophobic substrates. This work will thus provide further insights into the development of high-performance membranes for molecular separations.