Bioinspired: A 3D vertical silicon sponge-inspired construction of organic-inorganic loose mass transfer nanochannels for enhancing properties of polyimide nanofiltration membranes

Abstract

Nowadays, the separation efficiency and stability of nanofiltration (NF) membrane are of widespread concern. Inspired by the biomineralization phenomenon and its unique structure with siliceous framework, a polyimide (PI) NF membrane decorated with “silica hard phase-polymer soft phase” 3D interwoven sponge bionic structure was fabricated via a simple and effective one-step phase inversion strategy. The obtained membranes demonstrated high pure water permeability of 65 L/(m2·h) and rejections of Na2SO4 (91.55%) and NaCl (30.21%) at 0.4 MPa, respectively. Moreover, siliceous sponge-like structures were determined by SEM analysis, with the degree of cross-linking after membrane pore regulated as high as 88.89%. The integrity and long-term stability of the membrane in different organic solvents, including methanol, cyclohexane, acetone, ethyl acetate, n-heptane, absolute ethanol and toluene were maintained for 72 h at 0.8 MPa. Furthermore, the PI/SiO2 membrane with siliceous sponge biologically unique structure gives rise to a scope of bioinspired membranes and shows promising prospect for the treatment of solutions in extreme environments.