State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing, 210023, China; State Environmental Protection Engineering Center for Organic Chemical Wastewater Treatment and Resource Reuse, Nanjing, 210046, China.
Chemosphere. 2020 Dec;261:127717. doi: 10.1016/j.chemosphere.2020.127717. Epub 2020 Jul 20.
Polymer membranes for water treatment are constrained by the permeability-separation trade-off. Herein, two-dimensional (2D) zeolitic imidazolate frameworks (ZIFs) made of benzimidazole interconnected with Zn ions are used to create 2D Zn(Bim) molecular sieve nanosheets, which is explored as an asymmetric, thin-film composite (TFC) nanofiltration (NF) membrane for removing organic dyes and salts from water with a high water permeability under a low operating pressure (1 bar). The 2D Zn(Bim) TFC NF membrane is synthesized via ionic bonds between polycations and the peripheral hydroxy groups of 2D Zn(Bim) nanosheets, regulating the assembly of 2D Zn(Bim) to create a novel crack-free functional layer on top of a polyvinylidene fluoride (PVDF) ultrafiltration membrane. FESEM and XPS confirmed the presence of a polycations-regulated ultrathin functional layer with a thickness of ∼37 nm on the PVDF support. Benefiting from its structural feature, our 2D Zn(Bim) TFC NF membrane could achieve an ultra-high flux of ∼290 L/(m·h·bar) (5-10-fold higher than that of graphene-based membranes), good anti-fouling properties and high rejection rates (above 98%) for organic dyes. Moreover, the desalinization rate is 50-75%. That is, our membrane is endowed with NF capability, and its intrinsic ultrafiltration features (high water permeance, ultrafast, and energy-saving) are also well maintained.
用于水处理的聚合物膜受到渗透性-分离权衡的限制。在此，使用由苯并咪唑连接的锌离子构成的二维（2D）沸石咪唑酯骨架（ZIF）来制造 2D Zn（Bim）分子筛纳米片，将其作为不对称的、薄膜复合（TFC）纳滤（NF）膜来探索，用于在低操作压力（1 巴）下从水中去除有机染料和盐，同时具有高水透过率。2D Zn（Bim）TFC NF 膜是通过聚阳离子与 2D Zn（Bim）纳米片的外围羟基之间的离子键合成的，调节 2D Zn（Bim）的组装，在聚偏二氟乙烯（PVDF）超滤膜上形成新型无裂纹的功能层。FESEM 和 XPS 证实了在 PVDF 支撑体上存在聚阳离子调节的超薄功能层，其厚度约为 37nm。得益于其结构特点，我们的 2D Zn（Bim）TFC NF 膜可以实现超高通量约 290 L/（m·h·bar）（比基于石墨烯的膜高 5-10 倍），对有机染料具有良好的抗污染性能和高截留率（超过 98%）。此外，脱盐率为 50-75%。也就是说，我们的膜具有 NF 能力，并且其固有的超滤特性（高通量、超快、节能）也得到了很好的保持。
