College of Architecture and Environment, Sichuan University, Chengdu, 610065, China.
College of Architecture and Environment, Sichuan University, Chengdu, 610065, China; State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China.
Environ Res. 2021 Jul;198:111254. doi: 10.1016/j.envres.2021.111254. Epub 2021 May 7.
Most reported metal organic frameworks (MOFs) have microporous structures and defective active sites, limiting their practical application to macromolecular substances. A hierarchical porous zeolitic imidazolate framework-8 (ZIF-8) was prepared using poly(diallyldimethylammonium chloride) (PDDA) as a structure-directing agent under facile "aqueous room-temperature" conditions to increase the mass transfer and adsorption capacity tetracycline hydrochloride (TCH). The ZIF-8 pore structure and morphology were synchronously tuned by controlling the PDDA molecular weight and dosage. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Bruner-Emmett-Teller (BET), scanning electron microscopy (SEM), NH-temperature-programmed desorption (NH-TPD) and adsorption results revealed abundant pore structures and open metal sites in the prepared materials, along with excellent TCH adsorption performance compared with ZIF-8, despite decreased BET surface areas. Initial screens revealed large adsorption capacities of hierarchical porous ZIF-8P3(4) (976.8 mg g) due to the presence of more abundant unsaturated metal sites than ZIF-8 and novel hierarchical porous structures. Therefore, TCH adsorption on ZIF-8 and ZIF-8P3(4), including the kinetics, isotherms, thermodynamics and pH effect, was studied. The adsorption process follows pseudo-second-order kinetics and the Freundlich models better, indicating multilayer adsorption of TCH on the surface of the two absorbents. Adsorption behavior test, FTIR, XPS, BET and XRD results show that TCH adsorption on ZIF-8 and ZIF-8P3(4) most likely involves coordination bonds, electrostatic and π-π interactions, hydrogen bonds, and pore-filling effects. This study provides new insights into the template preparation of MOFs with high adsorption performance as potentially economical adsorbents to remove organic matter from contaminated water.
大多数报道的金属有机骨架（MOFs）具有微孔结构和有缺陷的活性位，限制了其在大分子物质中的实际应用。通过在简便的“水-室温”条件下使用聚二烯丙基二甲基氯化铵（PDDA）作为结构导向剂，制备了具有分级多孔沸石咪唑酯骨架-8（ZIF-8）的结构，以增加盐酸四环素（TCH）的传质和吸附容量。通过控制 PDDA 的分子量和用量，同步调节 ZIF-8 的孔结构和形貌。傅里叶变换红外光谱（FTIR）、X 射线衍射（XRD）、Brunauer-Emmett-Teller（BET）、扫描电子显微镜（SEM）、NH3-程序升温脱附（NH3-TPD）和吸附结果表明，所制备的材料具有丰富的孔结构和开放的金属位，与 ZIF-8 相比具有优异的 TCH 吸附性能，尽管 BET 比表面积有所降低。初步筛选结果表明，具有更多丰富不饱和金属位和新型分级多孔结构的分级多孔 ZIF-8P3(4)（976.8 mg g-1）具有较大的吸附容量。因此，研究了 ZIF-8 和 ZIF-8P3(4)对 TCH 的吸附，包括动力学、等温线、热力学和 pH 效应。吸附过程遵循准二级动力学和 Freundlich 模型，表明 TCH 在两种吸附剂表面的多层吸附。吸附行为测试、FTIR、XPS、BET 和 XRD 结果表明，TCH 吸附在 ZIF-8 和 ZIF-8P3(4)上可能涉及配位键、静电和π-π相互作用、氢键和孔填充效应。这项研究为具有高吸附性能的 MOFs 模板制备提供了新的见解，作为从受污染水中去除有机物的潜在经济型吸附剂。
