Abstract
Porous organic frameworks (POFs) based membranes have potential applications in molecular filtration, despite the lack of a corresponding study. This study reports an interesting strategy to get processable POFs dispersion and a novel ultrathin sandwich-like membrane design. It was accidentally found that the hydrophobic N-rich Schiff based POFs agglomerates could react with lithium-ethylamine and formed stable dispersion in water. By successively filtrating the obtained POFs dispersion and graphene oxide (GO), we successfully prepared ultrathin sandwich-like hybrid membranes with layered structure, which showed significantly improved separation efficiency in molecular filtration of organic dyes. This study may provide a universal way to the preparation of processable POFs and their hybrid membranes with GO.
Highlights
Combining adsorption and filtration is an efficient way to realize molecular separation for various applications with benefits of low energy consumption and easy operation[1,2,3]
Inspired by the graphene oxide (GO) membranes[11,12,13,14,15], we propose hereby an ultrathin sandwich-like membrane design (Fig. 1a), which can simultaneously increase the separation efficiency and the utilization
Our proof-of-concept demonstration is based on the use of processable N-rich Schiff based Porous organic frameworks (POFs) (SWN) (Fig. 1b) as the sorbent, and the GO nanosheets as two-dimensional (2D) interval layers
Summary
This study was started by an accidental finding during the interaction of SWN and lithium-ethylamine (Li-EDA). To explore the potential of porous organic frameworks in molecular filtration, ultrathin sandwich-like membranes with intercalated layers of GO and P-SWN were prepared by the successive filtration of GO and P-SWN dispersion through a PTFE support. Control experiments with a pure P-SWN membrane show the concentration of the effluent quickly reaches the feed concentration These results indicate that the sandwich-like hybrid membrane has higher stability than the membrane without GO, especially for the filtration process under a higher pressure. We demonstrated that the successively filtrating the obtained P-SWN and GO could be used to prepare a unique sandwich-like membrane with significantly improved separation efficiency in molecular filtration This novel membrane structure with horizontal fluidic channels can significantly increase the effective path length and increases the utilization of adsorption sites. The strategy and methods used here may be readily changed to prepare other processable POFs and hybrid membranes for applications in molecular filtration
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