Zhang Wen-Hai, Yin Ming-Jie, Zhao Qiang, Jin Cheng-Gang, Wang Naixin, Ji Shulan, Ritt Cody L, Elimelech Menachem, An Quan-Fu
Beijing Key Laboratory for Green Catalysis and Separation, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing, China.
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, China.
Nat Nanotechnol. 2021 Mar;16(3):337-343. doi: 10.1038/s41565-020-00833-9. Epub 2021 Jan 21.
The robustness of carbon nanomaterials and their potential for ultrahigh permeability has drawn substantial interest for separation processes. However, graphene oxide membranes (GOms) have demonstrated limited viability due to instabilities in their microstructure that lead to failure under cross-flow conditions and applied hydraulic pressure. Here we present a highly stable and ultrapermeable zeolitic imidazolate framework-8 (ZIF-8)-nanocrystal-hybridized GOm that is prepared by ice templating and subsequent in situ crystallization of ZIF-8 at the nanosheet edges. The selective growth of ZIF-8 in the microporous defects enlarges the interlayer spacings while also imparting mechanical integrity to the laminate framework, thus producing a stable microstructure capable of maintaining a water permeability of 60 l m h bar (30-fold higher than GOm) for 180 h. Furthermore, the mitigation of microporous defects via ZIF-8 growth increased the permselectivity of methyl blue molecules sixfold. Low-field nuclear magnetic resonance was employed to characterize the porous structure of our membranes and confirm the tailored growth of ZIF-8. Our technique for tuning the membrane microstructure opens opportunities for developing next-generation nanofiltration membranes.
碳纳米材料的稳健性及其超高渗透性的潜力在分离过程中引起了广泛关注。然而，氧化石墨烯膜（GOm）由于其微观结构的不稳定性，在错流条件和施加的液压下会导致失效，其可行性有限。在此，我们展示了一种高度稳定且超渗透的沸石咪唑酯骨架-8（ZIF-8）-纳米晶体杂化的GOm，它是通过冰模板法以及随后在纳米片边缘原位结晶ZIF-8制备而成。ZIF-8在微孔缺陷中的选择性生长扩大了层间距，同时也赋予了层状骨架机械完整性，从而产生了一种稳定的微观结构，能够在180小时内保持60 l m h bar的水渗透率（比GOm高30倍）。此外，通过ZIF-8生长减轻微孔缺陷使甲基蓝分子的渗透选择性提高了六倍。采用低场核磁共振来表征我们膜的多孔结构，并确认ZIF-8的定制生长。我们调节膜微观结构的技术为开发下一代纳滤膜开辟了机会。
