Abstract:

Zeolitic imidazolate frameworks (ZIFs) are considered to be one of the best materials for breaking through the upper limit of membrane materials due to their structure being adjustable, easy preparation and excellent stability. In this study, a high-performance dye desalination mixed matrix loose nanofiltration membrane was obtained by the in-situ growth of ZIF-L particles on a polyethyleneimine (PEI) based coating and followed by interfacial polymerization with trimesoyl chloride (TMC). Using the coordination action between PEI and Zn²⁺, the uniform distribution of Zn(Ⅱ) ions was ensured and also established an in-situ generation of ZIF-L nanoparticles with the polyamide interface, avoiding the formation of interface defects. The in-situ generation of ZIF-L particles increased the roughness of the membrane surface and improved the surface hydrophilicity, providing a water channel for the separation layer and shortening the water transport path. For the Congo red/salt mixed solution, compared with the PEI/TMC membrane without ZIF particle loading, the PEI(ZIF)/TMC membrane maintained the rejection rate unchanged, while the permeability was increased by nearly 17 times, reaching 68.1—71.7L/(m²·h·bar). The Congo red (CR) rejection rate was 98%. The Na₂SO₄ and NaCl rejection rates were 12.4% and 2.7%, and the separation selectivity coefficients were 7.8 and 36.1, respectively.

Key words: in-situ growth, dye/salt separation, ZIF-L, mixed matrix nanofiltration membrane, interfacial polymerization

摘要：

沸石咪唑酯骨架（ZIF）因其结构可调、制备简单以及稳定性优异，被认为是突破膜材料上限的最佳材料之一。本文通过在聚乙烯亚胺（PEI）基涂层原位生长ZIF-L粒子，然后与均苯三甲酰氯（TMC）界面聚合，得到了性能良好的染料脱盐混合基质疏松纳滤膜。利用PEI与Zn²⁺的配位作用，保证Zn(Ⅱ)离子的均匀分布，还建立了原位生成ZIF-L纳米粒子与聚酰胺之间的界面连接，避免了界面缺陷的形成。ZIF-L粒子的原位生成增加了膜表面粗糙度，改善了膜表面亲水性能，提供了分离层的水通道，缩短了水运输路径。对于刚果红（CR）/盐混合溶液，与未负载ZIF粒子的PEI/TMC膜相比，PEI(ZIF)/TMC膜在截留率维持不变的情况下，渗透系数提高近17倍，达到68.1~71.7L/(m²·h·bar)，其刚果红染料截留率达到98%，Na₂SO₄和NaCl截留率分别为12.4%和2.7%，截留分离选择系数分别为7.8和36.1。

关键词: 原位生长, 染料/盐分离, ZIF-L, 混合基质纳滤膜, 界面聚合