Preparation of poly(piperazine-amide) nanofilms with micro-wrinkled surface via nanoparticle-templated interfacial polymerization: Performance and mechanism

Incorporation of nanoparticles (NPs) into the polyamide (PA) selective layer is an effective way to improve the separation performance of nanofiltration (NF) membranes. However, the mechanism of permeability enhancement and the effect on membrane properties remain unclear. Here, different NPs-incorporated NF membranes were made through several nanoparticle addition strategies and used as an alternative approach for water desalination. NPs dispersed using pressure-deposition in amine-aqueous solution before the interfacial polymerization reaction exhibited a uniform micro-wrinkled morphology with increases in effective filtration area and thus a high water flux without the sacrifice of their selectivity. The loading density, shape, and size of NPs are the most important influential factors for the distribution and pattern of micro-wrinkled structures. Three NPs representatives, including MoS 2 nanosheets , UiO-66 octahedrons, and Au nanorods were used to tailor the morphology and their effect on the membrane performance was systematically investigated. The three TFN membranes under the optimal preparation conditions showed a high permeability without a sacrifice of salt rejections (Na 2 SO 4 >95%, and MgSO 4 >93%): 18.0, 16.8, and 16.0 L m -2  h -2 bar -1 for MoS 2 -TFN, UiO-66-TFN, and Au-TFN, respectively. Notably, all the membranes exhibited long-term structural stability. The NPs predeposition-induced micro-wrinkled method is a facile and viable strategy to enhance the performance of NF membranes, indicating their great potential in actual water desalination.