Emerging sandwich-like reverse osmosis membrane with interfacial assembled covalent organic frameworks interlayer for highly-efficient desalination

Covalent organic frameworks (COFs) have emerged as promising candidate for the construction of advanced separation membranes due to their well-defined pore structure and highly ordered porous channels. Nevertheless, the implementation of high-efficient COFs-incorporated membranes still suffers from harsh synthetic conditions and possible agglomeration of COFs. Herein, a kind of sandwich-like thin film composite reverse osmosis (RO) membranes was fabricated to overcome such challenges via interfacial assembly of a COFs interlayer on polysulfone substrate, then followed by the formation of a polyamide skin layer via traditional interfacial polymerization (IP) process. The COFs interlayer not only tailored the pore structure and interfacial properties of the substrate, but also manipulated the uptake and release of the amine monomer during the IP process, which would contribute to forming a more ordered polyamide separation layer. The resultant COFs-interlayered RO membrane exhibited a nearly 33.8% higher water permeance (16.78 L m−2 h−1 MPa−1) along with a slightly increased NaCl rejection (99.2%) compared with the pristine RO membrane. More importantly, the emerging RO membrane presented a superior chemical (critic acid and NaOH) resistance and desirable long-term filtration stability, which paved a new pathway to construct high-performance RO membranes for desalination. [Display omitted] •The RO membranes were prepared on interfacial assembled COFs interlayer.•COFs interlayer optimized physicochemical and interfacial properties of substrate.•The COFs-modulated IP procedure enabled a thinner, denser and smoother PA layer.•The PA/COFs/PSf membrane enhanced the optimal water permeance by up to 33.8%.•The COFs-interlayered RO membrane exhibited a satisfying long-term stability.