Diatom-Mimicking Ultrahigh-Flux Mesoporous Silica Thin Membrane with Straight-Through Channels for Selective Protein and Nanoparticle Separations

A nature-inspired mesoporous ultrafiltration membrane with unprecedented permeability and high selectivity for selective protein and nanoparticle separations is reported herein. We describe a diatom-mimicking hierarchically porous membrane that consists of a single-layer mesoporous silica thin film (MSTF) with perpendicular pores supported on top of a macroporous anodic aluminum oxide (AAO) membrane (MSTF⊥AAO) for ultrafiltration. The MSTF, with a thickness of ca. 30 nm, uniform vertical straight-through mesoporous channels (pore diameter of 5.9 ± 0.4 nm), superhydrophilicity, and continuous nonbreaking to centimeter range (area of 17.3 cm2), is overlaid on the AAO straight-through membrane, which counterintuitively exhibits both ultrahigh water permeability (1027 ± 20 L m–2 h–1 bar–1) and an excellent rejection rate (>99%) for molecules larger than 7 nm. The water permeability result is significantly higher than that of the reported nanosized channeled membranes. A model equation for calculating the theoretical permeability flux of the vertically nanochanneled membrane is established and compared with experimental results.