A vertically channeled lamellar membrane for molecular sieving of water from organic solvents

Abstract

Molecular sieve-based membranes are considered to be promising for achieving both high selectivity and permeability. Layered double hydroxides (LDHs) are typical two-dimensional crystalline compounds with highly uniform interlayer galleries that can be used to construct efficient molecular transport pathways. Herein, vertically channeled laminates are constructed on a tubular alumina substrate using CoAl–LDH as building blocks. Good-quality laminates are crystallized by direct nucleation and growth onto the alumina, in which alumina substrates act as both reactants and supports. Vertically aligned interlayer galleries are formed as sieving and transport channels for water molecules with the oriented nucleation effect of NH₄F. Compared with the zigzag pathways formed by two dimensional materials parallel to the substrate, the straight vertical channels have higher molecular transfer efficiency. As a result, the robust CoAl–LDH membranes show much higher and more stable organic solvent dehydration performance than most membranes under a wide range of feed conditions. This work thus demonstrates that LDH-based composite membranes are highly promising as the next generation of membranes for molecular sieving.