High-flux and selective membranes are key components to improving the energy efficiency of nanofiltration processes for water purification. Herein, we report high-flux polyamide thin-film composite (TFC) membranes consisting of Tröger's base for nanofiltration. Tröger's base diamine (TBD) was synthesized as an aqueous phase monomer for interfacial polymerization. Detailed characterization of TBD-based polyamides was performed using thermal, spectroscopic, and microscopic analyses. Notably, the V-shaped and rigid Tröger's base motif rendered TBD-based polyamide (named TBD-TMC) features with enhanced microporosity as well as an enlarged pore size compared to conventional polyamide chemistry (i.e., MPD-TMC). As a result, the TBD-TMC membrane exhibited a 570 % improvement in water permeance compared to MPD-TMC membranes while exhibiting moderate salt rejection up to 91 %, outperforming most reported nanofiltration membranes. Also, the TBD-TMC membrane exhibited high monovalent/divalent ion selectivity (∼7.0 for NaCl/Na2SO4 separation), which may have resulted from the combined effects of size exclusion and charge repulsion. This work highlights the potential of Tröger's base motif as a new diamine monomer for interfacially polymerized membranes to tune their microporous structures.

中文翻译：

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高通量聚酰胺薄膜复合膜，由 Tröger 的基序组成，具有增强的微孔性，适用于纳滤


高通量和选择性膜是提高水净化纳滤工艺能源效率的关键组件。在本文中，我们报道了由 Tröger 基座组成的高通量聚酰胺薄膜复合 （TFC） 膜，用于纳滤。Tröger 的碱二胺 （TBD） 被合成为用于界面聚合的水相单体。使用热、光谱和微观分析对基于 TBD 的聚酰胺进行了详细表征。值得注意的是，与传统的聚酰胺化学（即 MPD-TMC）相比，V 形和刚性 Tröger 的基序使基于 TBD 的聚酰胺（称为 TBD-TMC）具有增强的微孔性以及更大的孔径。因此，与 MPD-TMC 膜相比，TBD-TMC 膜的透水率提高了 570%，同时表现出高达 91% 的适度脱盐率，优于大多数报道的纳滤膜。此外，TBD-TMC 膜表现出高一价/二价离子选择性（NaCl/Na2SO4 分离为 ∼7.0），这可能是尺寸排斥和电荷排斥的综合效应造成的。这项工作突出了 Tröger 碱基序作为新型二胺单体的潜力，用于界面聚合膜以调整其微孔结构。