Abstract Synthesis of a continuous and intergrown metal-organic framework (MOF) membrane remains a challenging issue due to the grain boundary defects and intercrystalline cracks in MOF thin film. In this study, a ZIF-8 membrane was fabricated by using a plant polyphenol tannic acid (TA) layer as an intermediate layer to overcome this issue. Specifically, a TA layer was constructed on a polyethersulfone substrate via a facile and environmentally friendly aqueous coating process. Thereafter, the above modified membrane was immersed into a Zn(Ac)2 and Hmim mixture solution for in-situ growing a ZIF-8 thin film on membrane surface. It was found that the abundant pyrogallol groups in TA layer could coordinate with Zn2+ ions, promote heterogeneous nucleation and contribute to a continuous and intergrown ZIF-8 thin film. The as-prepared ZIF-8 membrane showed a pure water permeance of 3.6 L m−2 h−1 bar−1 with NaCl and Na2SO4 rejections of 64.7% and 92.2% respectively, overwhelming the controlled ZIF-8 membrane without TA as intermediate layer in both permeability and selectivity. This membrane is one of few MOF membranes that have a divalent salt rejection higher than 90%, demonstrating its great potential application in efficient desalination.

中文翻译：

---

用于高效脱盐的植物多酚中间金属有机骨架 (MOF) 膜

摘要 由于 MOF 薄膜中的晶界缺陷和晶间裂纹，连续共生金属有机骨架 (MOF) 膜的合成仍然是一个具有挑战性的问题。在这项研究中，通过使用植物多酚单宁酸 (TA) 层作为中间层来制造 ZIF-8 膜来克服这个问题。具体来说，TA 层是通过一种简便且环保的水性涂层工艺在聚醚砜基材上构建的。之后，将上述改性膜浸入Zn(Ac)2和Hmim混合溶液中，在膜表面原位生长ZIF-8薄膜。发现 TA 层中丰富的连苯三酚基团可以与 Zn2+ 离子配位，促进异相成核并有助于形成连续和共生的 ZIF-8 薄膜。所制备的 ZIF-8 膜的纯水渗透率为 3.6 L m-2 h-1 bar-1，NaCl 和 Na2SO4 截留率分别为 64.7% 和 92.2%，压倒了不含 TA 作为中间层的受控 ZIF-8 膜在渗透性和选择性方面。该膜是为数不多的二价盐截留率高于 90% 的 MOF 膜之一，表明其在高效脱盐方面具有巨大的应用潜力。