Dendritic Mesoporous Silica Nanosphere-Embedded Polyacrylonitrile Electrospun Composite Nanofiltration Membrane with Crumpled Structure and High Water Permeance

An electrospun membrane with a highly interconnected pore network and low tortuosity is considered as a promising porous support substrate to prepare a nanofiltration (NF) membrane, while it still remains a great challenge to improve the water permeability of the electrospun NF membrane. Therefore, in this study, flower-like dendritic mesoporous silica nanospheres (DMSNs) were embedded into a polyacrylonitrile (PAN) electrospun membrane to regulate the surface structure and interfacial polymerization process, fabricating DMSNs embedded in a PAN electrospun composite NF membrane (PAN–DMSNs–PA). It is found that the embedded DMSNs could reduce the thickness of the polyamide (PA) layer and form a crumpled surface morphology. Moreover, DMSN embedment could lower the negative zeta potential, molecular cutoff, and pore size distribution of the composite NF membrane. The NF performance data show that though PAN–DMSNs–PA composite membranes have similar Evans blue and MgSO4 rejection rates with PAN–PA membrane, they have higher water permeance values. The optimized PAN–DMSNs100–PA membrane has a pure water permeance value of 26.42 L m–2 h–1 bar–1, which is about 1.3 times the pure water permeance value of the PAN–PA membrane, and its rejection order follows the sequence of MgSO4 (96.4%) > Na2SO4 (82.5%) > MgCl (41.0%) > NaCl (32.2%). This study provides an effective way to synthesize high-quality NF membranes.