2D COFs interlayer manipulated interfacial polymerization for fabricating high performance reverse osmosis membrane

Abstract

Covalent organic frameworks (COFs) have been widely used to prepare separation membranes due to their high porosity. In this work, a kind of thin-film nanocomposite (TFN) reverse osmosis (RO) membrane was fabricated by forming a polyamide (PA) selective layer on an in-situ constructed two-dimensional COFs intermediate layer. The TFN RO membrane has a much smooth (∼48 nm) and defect-free PA layer due to the regulated interfacial polymerization (IP) process with the assistance of the conterminous COFs interlayer, thereby achieving synchronously improved water permeance of 29.8 L m−2 h−1 MPa−1 and salt rejection of 99.4 %, as well as excellent chemical stability, including acid / alkali, fouling and chlorine resistance. Moreover, the COFs-interlayered TFN RO membrane exhibited promising separation performance after 80 h long-term filtration test. The current work offers fundamental insights into the critical roles of COFs interlayer in tailoring the IP process and the physicochemical properties of the PA layer, providing a novel strategy for enhancing the separation performance of RO membranes towards efficient desalination and sustainable water purification.