Abstract
Fabrication of high-rejection covalent organic framework (COF) membranes for desalination remains a significant challenge, due to processing limitations and substrate mismatches. Herein, we report an ethanol-assisted self-assembly strategy for preparing high-rejection COF membranes from anionic TpPa-SO3Na COF (SCOF) nanosheets. This method promotes SCOF dispersion in ethanol with high aspect-ratio structures and elimination of interlayer charge, thus facilitating the formation of defect-free SCOF membranes (COFMs). Furthermore, polyvinyl alcohol (PVA) was used to modify commercial polyethylene (PE) supports ensuring compatibility with the high-rejection SCOF layers. The hydrophilic PVA@PE support with appropriate surface pore induces the SCOF nanosheets to form a complete stacking structure. The resultant COFM (MEtOH) exhibit an impressive Na2SO4 rejection rate of 98.83 % and a pure water flux of 4.35 L m−2 h−1, demonstrate exceptional rejection stability under elevated pressure, acidic or alkaline conditions, and high salt concentrations. The superior desalination performance of the COFMs surpasses the most reported 2D desalination membranes.
Published Version
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