A continuous and ultra-thin metal-phenolic network top layer on a polyethersulfone substrate surface was used as metal precursor for a metal-organic framework (MOF) membrane synthesis. A plant polyphenol tannic acid (TA) and Zn²⁺ based network top layer prepared by a layer-by-layer (LBL) self-assembly process was immersed into a 2-methylimidazole aqueous solution, and then a ZIF-8 top layer was facilely formed due to the partial self-conversion of TA-Zn²⁺ network to ZIF-8. The LBL process provides sufficient controllability of preparing a continuous and ultra-thin ZIF-8 top layer, which are crucial factors for nanofiltration membrane separation performance. The optimized ZIF-8 membrane exhibited a pure water permeance (PWP) of 5.1 L m⁻² h⁻¹ bar⁻¹, a 55.2% NaCl rejection and a 93.6% Na₂SO₄ rejection. This is one of the few MOF membranes that possesses a divalent inorganic salt rejection higher than 90%. The novel zinc source of ZIF-8 synthesis disclosed in this study can provide a new incentive to not only MOF membrane preparation but also engineering MOFs towards a wide energy and environmental applications.

聚醚砜基质表面上的连续且超薄的金属-酚醛网络顶层用作金属-有机骨架（MOF）膜合成的金属前体。将通过逐层（LBL）自组装工艺制备的植物多酚单宁酸（TA）和Zn ²⁺基网络顶层浸入2-甲基咪唑水溶液中，然后将ZIF-8顶层由于TA-Zn ²⁺网络部分自转化为ZIF-8 ，因此易于形成。LBL工艺为制备连续且超薄的ZIF-8顶层提供了足够的可控性，这是纳滤膜分离性能的关键因素。优化的ZIF-8膜的纯水渗透率（PWP）为5.1 L m ^-2  h ^-1bar ^-1，NaCl排斥率为55.2％，Na ₂ SO ₄排斥率为93.6％。这是少数具有高于90％的二价无机盐截留率的MOF膜之一。这项研究中公开的ZIF-8合成的新型锌源不仅可以为MOF膜的制备提供新动力，而且还可以将MOF工程化以实现广泛的能源和环境应用。