COF membranes with fast and selective of water‐transport channels for efficient ethanol dehydration

Abstract Laminar‐structured covalent organic framework (COF) membranes hold great promise in molecular separation. Precise nanochannel manipulation of laminar‐structured COF membranes is of critical significance. In this study, COF membranes are engineered by assembling COF‐TbTG nanosheets and sulfobutylether‐ β ‐cyclodextrin (SCD) into laminar structures. The interlamellar spaces of COFs are regulated to achieve molecular sieving for precise separation; the intrinsic pores of COFs are utilized as fast molecule‐transport channels. The obtained COF membranes exhibit a superior ethanol dehydration performance with a permeation flux of 5.2 kg m −2 h −1 and a separation factor of 1072, which exceeds the performances of state‐of‐the‐art membranes for water/ethanol separation. Moreover, the optimal membranes show a steady permeation flux maintaining around 5.0 kg m −2 h −1 during a 72‐h operation test. This work may provide a new approach to the design of molecular‐sieving COF membranes for precise separation.