Dual-layer membrane with hierarchical hydrophobicity and transport channels for nonpolar organic solvent nanofiltration

Nonpolar solvent separation is widely used in petroleum, chemical, food industries, but traditional separation methods consume intensive energy. State-of-art organic solvent nanofiltration membranes require complex modifications for nonpolar solvent transport. For the first time, we propose the concurrent modification of the surface, interface and support layer of dual-layer membranes with three additives (perfluorodecylamine, fluoro substituted aromatic amine, silica nanoparticles) in a one-step cocasting process. A delamination-free dual-layer membrane was obtained with a hierarchical hydrophobicity and transport channels. The novel designed structure elevated the pure n-hexane permeance (28.75 L m⁻² hr⁻¹ bar⁻¹) by 3 orders of magnitude with a high lecithin rejection (98.7%). This method of synergistically controlling the hierarchical structures and properties of dual-layer membranes can significantly shorten the preparation process of high-performance nonpolar solvent nanofiltration membranes.