Fabrication of Porous Organic Framework/Graphene Oxide Hybrid Membrane with Sandwich-like Structure for Molecular Separation
Yuanzhi Zhu, Yang Li, Wenchao Peng, Guoliang Zhang, Fengbao Zhang and Xiaobin Fan*
School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072, China. E-mail: firstname.lastname@example.org Fax: +86-22-27890090
Combining adsorption and filtration is an efficient way to realize molecular separation with low energy consumption and easy operation benefits. Porous organic frameworks (POFs), which are formed by covalent cross-linking of diverse organic moieties, can be good candidates for molecular separation due to its large surface area, rigid porous skeleton and high chemical stability. Inspired by the graphene oxide (GO) membranes, we present hereby a novel sandwich-like membrane design, which is based on the use of dispersible N-rich Schiff based POFs (SWN) as the sorbent, and the GO sheets as two-dimensional (2D) open interval layers. By alternately filtrating the SWN and GO dispersion, the sandwich-like hybrid membranes with different layered structures can be easily fabricated. Methyl orange (MO) was used as the probe to study the filtration performances of the as-prepared hybrid membranes. The breakthrough curves fit by Boltzmann model shows that the breakthrough volume (VB) and adsorption capacity (Q) of the membranes with SWN loading of ~0.67mg quickly increases when the layer numbers increased from 1 to 4, but it becomes gradually stagnant when more GO layers are introduced. Based on the Werkhoven-Goëwie model, the theoretical plates (N) of the sandwich-like membrane with an optimized layers number can be calculated to 21.83, which is about 4.5-fold of the pure SWN membrane. The improvements of separation efficiency should be attributed to the increased effective path length and higher utilization ratios of the adsorption sites. The VB and Qof the membranes can be easily scaled up by increasing the loading of SWN. Besides, the membrane can be repeatedly used for at least 7 times without decline of its performance. The strategy and methods used here may be readily changed to prepare other processable POFs and hybrid membranes with potential applications in molecular filtration.
Porous organic frameworks; Graphene oxide; Sandwich-Like membrane; Molecular Separation
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