Zhao Yang-Ying, Liu Yan-Ling, Wang Xiao-Mao, Huang Xia, Xie Yuefeng F
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment , Tsinghua University , Beijing 100084 , China.
Environmental Engineering Programs , The Pennsylvania State University , Middletown , Pennsylvania 17057 , United States.
ACS Appl Mater Interfaces. 2019 Apr 10;11(14):13724-13734. doi: 10.1021/acsami.9b01923. Epub 2019 Mar 26.
Metal-organic frameworks (MOFs), a class of hybrid organic-inorganic materials, have recently attracted tremendous interests in the fabrication of thin-film nanocomposite (TFN) membranes with exceptional permselectivity. However, the structure-performance relationship of such membranes, which is a function of both MOF type and membrane fabrication procedure, has not been elucidated in the literature. In this study, three types of hydro-stable MOFs, namely, MIL-53(Al), NH-UiO-66, and ZIF-8, were used to fabricate TFN nanofiltration membranes via both blending (BL) and preloading interfacial polymerization methods. Results show that the incorporation of MOFs could enhance water permeability of TFN membranes to 7.2 L/(m·h·bar) at most ( TFN-BL-0.10%), about 1.3 times of the corresponding thin-film composite membranes, without sacrificing their selectivity to reject NaCl (>40%) and xylose (>65%). Membrane characterization revealed that MOFs decreased the cross-linking degree while increasing the membrane thickness, surface negative charge, and roughness of the polyamide active layer. MIL-53(Al) were found to bind with polyamide via reacting with piperazine, whereas weaker polyamide-MOF interactions were observed for NH-UiO-66 and ZIF-8. This difference, along with the hydrophilicity of MOF particles, explained the varied permselectivity of different TFN membranes. Compared to pristine polyamide membranes, the TFN membranes demonstrated higher or comparable efficiencies in removing a set of six pharmaceuticals (PhACs), which were determined by the molecular properties of PhACs and membrane structure. The findings of this study deepen our understanding of the roles that MOFs play in regulating membrane performance, promoting molecular design of MOF-incorporated TFN membranes via precise control of MOF-polymer interactions.
金属有机框架材料（MOFs）是一类有机-无机杂化材料，最近在制备具有卓越渗透选择性的薄膜纳米复合（TFN）膜方面引起了极大的关注。然而，这类膜的结构-性能关系，它是MOF类型和膜制备工艺两者的函数，在文献中尚未得到阐明。在本研究中，三种水稳定的MOFs，即MIL-53(Al)、NH-UiO-66和ZIF-8，通过共混（BL）和预负载界面聚合方法用于制备TFN纳滤膜。结果表明，MOFs的掺入最多可将TFN膜的水渗透率提高到7.2 L/(m·h·bar)（TFN-BL-0.10%），约为相应的薄膜复合膜的1.3倍，同时不牺牲其对NaCl（>40%）和木糖（>65%）的截留选择性。膜表征显示，MOFs降低了交联度，同时增加了聚酰胺活性层的膜厚度、表面负电荷和粗糙度。发现MIL-53(Al)通过与哌嗪反应与聚酰胺结合，而对于NH-UiO-66和ZIF-8观察到较弱的聚酰胺-MOF相互作用。这种差异，连同MOF颗粒的亲水性，解释了不同TFN膜的不同渗透选择性。与原始聚酰胺膜相比，TFN膜在去除一组六种药物（PhACs）方面表现出更高或相当的效率，这取决于PhACs的分子性质和膜结构。本研究的结果加深了我们对MOFs在调节膜性能中所起作用的理解，通过精确控制MOF-聚合物相互作用促进了含MOF的TFN膜的分子设计。
