Highly permeable polyamide nanofiltration membranes with crumpled structures regulated by polydopamine-piperazine-halloysite interlayer

Highly selective and permeable nanofiltration (NF) membranes are desirable for energy-efficient desalination and water treatment. However, the preparation of NF membranes with thinner defect-free selective layers and high separation performance remains challenging. Here a new strategy is reported for designing an NF membrane with a crumpled selective layer using polydopamine-piperazine-halloysite nanotubes (PDP-HNTs) as an interlayer and fabricated through vacuum filtration assisted interfacial polymerization (VFIP) method. Specifically, the PDP-HNTs/piperazine (PIP) dispersion was loaded onto the substrate surface through vacuum filtration, achieving construction of the interlayer and loading of the aqueous phase in one step. The PDP-HNTs interlayer served as a regulator to control the selective layer morphologies by retarding the polymerization reaction, forming an NF membrane with loose and crumpled structures. The resulting membranes display a high performance with the water permeance of 45.3 L m−2 h−1 bar−1, while maintaining a Na2SO4 rejection of 97.1 %. Because of the versatility and simplicity of this strategy, our work provides a new approach for fabricating NF membranes with outstanding separation performance.