水稳定性金属有机骨架材料对铀吸附研究进展

以水稳定性MOFs为研究对象,综述了国内外吸附处理含铀废水的研究现状,重点阐述了不同类型和结构的水稳定性MOFs有效吸附含铀废水的最新进展,特别是改性、复合MOFs可以提高MOFs的吸附性能。最后,我们提出了对开发水稳定性MOFs的个人见解和未来展望。     

金属有机骨架用于气体存储、吸附分离的研究进展

金属有机骨架(MOFs)由于具有大比表面积、高孔隙率、可调孔径、结构多样、开放的金属位点和化学可修饰性等诸多优点而被广泛用于气体的吸附分离研究。本文对近年来MOFs在气体存储、吸附分离领域的研究进展进行了综述,讨论了不同MOFs对氢气、甲烷的存储性能和存储机理及对二氧化碳、低碳烃等的分离性能和吸附机理,指出MOFs材料的比表面积、孔结构、金属位点、π-π键合作用、可修饰基团等是影响不同MOFs吸附分离过程的重要参数。有目的的功能化改性是提高MOFs材料选择性吸附分离性能的有效方法,但目前仍普遍存在存储吸附性能不够、稳定性不强、成本过高等问题,只有解决这些问题才能使MOFs大量从实验室走向工业化。     

柔性金属有机骨架材料(MOFs)用于气体吸附分离

柔性金属有机骨架材料(MOFs)具有高度有序的网络结构与可变形的骨架,其骨架结构会对外界的温度、压力及客体分子的刺激产生独特的结构响应。近几年来,柔性MOFs在气体吸附、气体分离、传感等领域显示出巨大的应用潜力。截至目前,研究者们对柔性MOFs的研究仅局限于对其结构形变的机理解释,而缺乏对柔性MOFs应用于相关化工过程的性能研究。本文着重对近年来柔性MOFs在气体吸附分离领域的研究进展进行了综述,并详细地分析了柔性MOFs结构与其气体吸附分离性能之间的构效关系。通过分子模拟结合实验,讨论了柔性MOFs结构对气体分子的平衡吸附与动力学扩散的影响。分析表明,设计合成具有良好吸附选择性与扩散性能的柔性MOFs是其应用于绿色、高效气体分离过程的重要发展方向。     

金属有机骨架材料吸附去除环境污染物的进展

金属有机骨架材料(MOFs)具有超高的比表面积、较高且可调的孔隙率、结构组成多样性、开放的金属位点和化学可修饰等优点,近年来在选择性吸附领域中的应用受到人们的广泛关注。本文综述了MOFs在液相吸附去除各种环境污染物方面的应用进展,包括吸附去除水中的有机污染物、重金属离子以及吸附去除燃油中的有机含硫化合物和有机含氮化合物;讨论了不同MOFs及改性MOFs对环境污染物的吸附性能及吸附机理,指出MOFs的孔结构、开放的金属位点、静电吸附作用、π-π键合作用、氢键作用、酸碱吸附作用等是影响MOFs吸附过程的重要参数或机理,而通过对MOFs进行有目的的功能化改性可以提升MOFs对目标污染物的吸附性能;最后展望了MOFs吸附去除环境污染物今后的研究热点。     

金属-有机框架材料的调控策略及其对典型重金属离子的吸附性能

金属-有机框架材料(MOFs)相较于传统吸附材料具有较大的比表面积、可调的孔隙和拓扑结构、丰富的活性官能团等优点，可作为高性能吸附剂去除水体中的重金属污染物。本文介绍了MOFs作为水处理吸附的结构特性，重点分析了基于金属节点掺杂、侧基功能化和合成后修饰的多孔性、表面活性、框架柔性、水稳定性、可扩展性、生物毒性和循环使用性MOFs的调控策略，而后介绍了MOFs在去除重金属离子方面的研究进展，详细介绍了MOFs对水中Pb(Ⅱ)、Hg(Ⅱ)等阳离子型重金属离子和Cr(Ⅵ)、As(Ⅲ)/As(Ⅴ)等阴离子型含氧离子的吸附性能，并阐述MOFs去除水中重金属离子的作用机理。最后，提出了提升MOFs的水稳定性与吸附性能、平衡MOFs结构特性的关系、研究MOFs在自然界的迁移与富集以及MOFs的低成本高效益的可控性制备等研究方向，以期对MOFs在高性能吸附领域提供参考。     

基于海水提铀的多孔芳香框架材料研究进展

多孔芳香框架材料是一类新兴的有机多孔纳米材料，具有稳定性高、比表面积大、易于修饰改性等特点，可以满足多种吸附材料设计的需求。近几年众多学者将修饰改性后的多孔芳香框架材料应用于海水提铀，发现其具有较大的铀吸附量、优异的铀选择性、良好的可循环性等特点。本文综述了近年来基于海水提铀的多孔芳香框架材料的研究进展，首先简要介绍了其合成反应与合成技术，然后分类讨论了与铀的相互作用机理，并评估了多种改性多孔芳香框架材料对铀的吸附性能，分析了其对铀的高选择性和高吸附效率的原因。最后，本文针对目前多孔芳香框架材料在海水提铀中的局限性（多孔芳香框架材料的合成、吸附性能的提高、成本的降低及机理的深层次研究等）为未来设计低成本高性能的多孔芳香框架材料吸附剂提供了几点建议。     

金属有机骨架材料多功能阻燃聚合物应用研究进展

简要介绍了具有高孔隙率、催化吸附等特性的金属有机骨架（MOFs）材料的分类及合成方法,分别从改性以及未改性MOFs材料在聚合物中的阻燃应用及阻燃机理来阐述了近年来MOFs材料在聚合物材料阻燃方面的研究现状。最后,对其MOFs材料的应用前景进行了总结与展望。     

疏水性金属-有机骨架材料的研究进展

金属-有机骨架（metal-organic frameworks, MOFs）材料是一种由金属离子和有机配体通过自组装形成的新型多孔材料，具有优异的物理及化学性能，因而在气体吸附储存、气体分离以及工业催化等方面表现出良好的应用潜力。但在应用的过程中，无处不在的水分子会影响MOFs骨架的稳定性和吸附性能，极大地制约了其实际应用。本文介绍了近年来疏水性MOFs材料的研究进展，重点论述了金属离子和有机配体对调控MOFs亲疏水性的影响以及通过配体后修饰和疏水性物质复合等提高疏水性的方法，分析了MOFs材料的亲疏水性机理，同时提出了实验结合计算机模拟技术筛选疏水性MOFs的手段。最后，指出目前疏水性MOFs材料合成存在的问题及解决方法，期望为今后拓宽MOFs材料在高湿环境中的应用提供一些有用的参考。     

MOFs分离膜在水系分离中的应用

MOFs作为一类具有三维孔结构的新型框架材料,在催化、储能和分离领域均有广泛的应用前景,而MOFs的水稳定性一直是限制其扩大应用的壁垒。随着水稳定性MOFs材料不断涌现以及人们对MOFs水稳定性机理认识的加深,众多的学者开始关注MOFs分离膜在水体系下物质分离的应用研究。综述了围绕MOFs分离膜在水系环境下的分离应用研究展开,概述了MOFs水稳定性的影响因素,MOFs分离膜的制备及其在染料废水处理、脱盐、重金属离子去除和离子选择性分离等领域的应用研究,并对MOFs分离膜未来发展趋势进行了展望。     

MOFs分离膜在水系分离中的应用

MOFs作为一类具有三维孔结构的新型框架材料,在催化、储能和分离领域均有广泛的应用前景,而MOFs的水稳定性一直是限制其扩大应用的壁垒。随着水稳定性MOFs材料不断涌现以及人们对MOFs水稳定性机理认识的加深,众多的学者开始关注MOFs分离膜在水体系下物质分离的应用研究。综述了围绕MOFs分离膜在水系环境下的分离应用研究展开,概述了MOFs水稳定性的影响因素,MOFs分离膜的制备及其在染料废水处理、脱盐、重金属离子去除和离子选择性分离等领域的应用研究,并对MOFs分离膜未来发展趋势进行了展望。     

金属有机框架材料的水稳定性及吸水应用进展

水蒸气广泛存在于空气和工业气体中,收集利用或去除水蒸气都需要利用高吸水储水的吸附剂。金属有机框架材料（metal-organic frameworks,MOFs）作为一种具有高孔隙率、高比表面积的新型多孔材料,同时具备网状结构和孔径可控调节的特性,被广泛应用于吸附、分离、催化、过滤等多个领域。将MOFs应用于水吸附领域不仅要求MOFs具备较高的水稳定性,还需要具备亲水和吸附-脱附循环能力。本文综述了水稳定性MOFs的基本组成,基于皮尔森软硬酸碱理论的设计原则,水吸附行为的影响因素以及空气集水、气体除湿等应用领域的进展,以饱和吸湿量为参考罗列了13种水吸附MOFs及其衍生物的物理参数。最后总结了水吸附MOFs在合成机理、批量制备和应用领域存在的问题,并对应提出了解决思路,期望为MOFs在水吸附应用的研究方向提供有价值的参考。     

沸石材料的改性及其对水体污染物的吸附性能

吸附法以其选择性强、操作简易、二次污染少等优势逐步成为污水处理的重要方法。天然沸石材料具有孔腔结构丰富、吸附成本低廉以及吸附性能高等优势,但存在选择吸附性差、与水相分离困难、再生成本偏高等问题。通过改性,可以为沸石吸附剂对阴离子污染物的吸附提供更多吸附活性位点。本文基于沸石材料改性制备的国内外最新研究进展,总结了不同改性材料制备复合吸附材料的研究工作,重点介绍了沸石材料改性方法及其应用,进一步回顾了改性沸石材料对水中污染物的吸附性能和影响因素。通过改性提高沸石材料的选择吸附性能及吸附后的绿色再生将是推动沸石吸附材料规模化应用发展的核心。     

Moisture stability of ethane-selective Ni(II), Fe(III), Zr(IV)-based metal–organic frameworks

Metal–organic frameworks (MOFs) combined with selective adsorption capacity of ethane over ethylene and good moisture stability are highly urged by adsorption industrial community. Here, the moisture stability mechanism of Zr-bptc, UiO-66, PCN-245, and Ni(bdc)(ted)_0.5 were investigated by moisture stability experiments, and computational simulation of metal node-linker breaking energy caused by water. Results show that the moisture stability follows the order of Zr-bptc > UiO-66 > PCN-245 > Ni(bdc)(ted)_0.5. The different moisture stability for these MOFs is likely attributed to the bond strength between metal center and ligands, the coordination number of metal center, the hydrophobicity of framework, as well as the degree of interpenetrated framework. Additionally, comparing with ethylene-selective MOFs, ethane-selective MOFs have fewer coordinatively unsaturated metal sites. Breakthrough experiments indicated that Zr-bptc is the promising material for ethane/ethylene separation.     

金属有机骨架(MOFs)为壳的核壳结构材料研究进展

MOFs核壳结构材料是近十几年来化工材料领域的研究热点, 其中MOFs可作核, 亦可作壳。本文从不同的核出发综述了以MOFs为壳的核壳结构材料的合成方法, 如外延生长法、后合成修饰法等;概述了其展现出优于核层与壳层的特性(如选择性分离、催化性、磁性等)及以 MOFs为壳的核壳结构材料在气体吸附、催化剂、磁性分离等应用上的研究, 这给MOFs复合材料的产业化带来很大的潜力;而内核主要包括单质金属及非金属类内核、氧化物类内核、MOFs类内核;最后对MOFs为壳的核壳结构复合材料合成方法的改进和拓展、结构均一稳定、多功能化的发展作了展望。     

New and simple synthetic strategy for two-dimensional ultra-microporous aromatic framework for selective uranium capture in liquid

Uranium is a key element to improve nuclear energy demands, and thereby the extraction of uranium from seawater is a strategic way to address uranium sustainability. Herein, a novel two-dimensional porous aromatic framework (AO-PAF), which possesses an ultra-microporous architecture with an ordered structure, excellent stability and selectivity of uranium extraction from a liquid phase. AO-PAF shows excellent uranium adsorption capacities of 637 (mg/g) and 3.22 (mg/g) in simulated and natural seawater attributable to the selective uranium coordinating groups on highly accessible pores on the walls of open channels. In addition, benefiting from the super-hydrophilicity due to the presence of amidoxime groups attributes high selectivity and ultrafast kinetics with an uptake rate of 0.43 ± 0.03 (mg/g·day) and allowing half-saturation within 1.35 ± 0.09 days. This strategy demonstrates the potential of PAF not only recovery of uranium and can be extended for other applications by sensible planning of target ligands.     

Metal-organic frameworks for analytical chemistry: from sample collection to chromatographic separation

In modern analytical chemistry researchers pursue novel materials to meet analytical challenges such as improvements in sensitivity, selectivity, and detection limit. Metal-organic frameworks (MOFs) are an emerging class of microporous materials, and their unusual properties such as high surface area, good thermal stability, uniform structured nanoscale cavities, and the availability of in-pore functionality and outer-surface modification are attractive for diverse analytical applications. This Account summarizes our research on the analytical applications of MOFs ranging from sampling to chromatographic separation. MOFs have been either directly used or engineered to meet the demands of various analytical applications. Bulk MOFs with microsized crystals are convenient sorbents for direct application to in-field sampling and solid-phase extraction. Quartz tubes packed with MOF-5 have shown excellent stability, adsorption efficiency, and reproducibility for in-field sampling and trapping of atmospheric formaldehyde. The 2D copper(II) isonicotinate packed microcolumn has demonstrated large enhancement factors and good shape- and size-selectivity when applied to on-line solid-phase extraction of polycyclic aromatic hydrocarbons in water samples. We have explored the molecular sieving effect of MOFs for the efficient enrichment of peptides with simultaneous exclusion of proteins from biological fluids. These results show promise for the future of MOFs in peptidomics research. Moreover, nanosized MOFs and engineered thin films of MOFs are promising materials as novel coatings for solid-phase microextraction. We have developed an in situ hydrothermal growth approach to fabricate thin films of MOF-199 on etched stainless steel wire for solid-phase microextraction of volatile benzene homologues with large enhancement factors and wide linearity. Their high thermal stability and easy-to-engineer nanocrystals make MOFs attractive as new stationary phases to fabricate MOF-coated capillaries for high-resolution gas chromatography (GC). We have explored a dynamic coating approach to fabricate a MOF-coated capillary for the GC separation of important raw chemicals and persistent organic pollutants with high resolution and excellent selectivity. We have combined a MOF-coated fiber for solid-phase microextraction with a MOF-coated capillary for GC separation, which provides an effective MOF-based tandem molecular sieve platform for selective microextraction and high-resolution GC separation of target analytes in complex samples. Microsized MOFs with good solvent stability are attractive stationary phases for high-performance liquid chromatography (HPLC). These materials have shown high resolution and good selectivity and reproducibility in both the normal-phase HPLC separation of fullerenes and substituted aromatics on MIL-101 packed columns and position isomers on a MIL-53(Al) packed column and the reversed-phase HPLC separation of a wide range of analytes from nonpolar to polar and acidic to basic solutes. Despite the above achievements, further exploration of MOFs in analytical chemistry is needed. Especially, analytical application-oriented engineering of MOFs is imperative for specific applications.     

Molecular simulation studies of separation of CH4/H2 mixture in metal-organic frameworks with interpenetration and mixed-ligand

In our previous work, we have investigated the adsorption selectivity of CH₄/H₂ in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without interpenetration to study the effect of interpenetration on gas mixture separation through Monte Carlo simulation. In addition, the self-diffusivities and the diffusion mechanism of single H₂ and CH₄ in these MOFs were examined by molecular dynamics simulations. In this work, we extend our previous work to mixed-ligand MOFs to investigate the effects of interpenetration as well as mixed-ligand on both equilibrium-based and kinetic-based gas mixture separation. We found that methane adsorption selectivity is much enhanced in the selected mixed-ligand interpenetrated MOFs compared with their non-interpenetrated counterparts, similar to what we found before for IRMOFs with single-ligand. At room temperature and atmospheric pressure, molecular-level segregation was observed in the mixed-ligand MOFs, and the extent of the effects of interpenetration is comparable for single-ligand and mixed-ligand MOFs. In addition, we found that the diffusion selectivity in the interpenetrated MOFs is similar to the one in their non-interpenetrated counterparts, while the permeation selectivity in the former is much higher than that in the latter, which corroborates our expectation that interpenetration is a good strategy to improve the overall performance of a material as a membrane in separation applications based only on the single component diffusion results. Furthermore, the CH₄ permeability of the selected MOF membrane was also evaluated.     

铪金属-有机骨架材料的孔尺寸调控及其吸附性能

利用三种不同长度的有机配体--反丁烯二酸（H₂FUM）、对苯二甲酸（H₂BDC）和联苯二甲酸（H₂BPDC）,合成了一系列具有不同孔尺寸的新型铪（Hf）金属-有机骨架（MOF）材料（Hf-FUM、Hf-BDC和Hf-BPDC）,并考察了CO₂、N₂和CH₄三种气体在这些材料中吸附分离行为。研究结果表明,这三种材料具有和UiO-66（Zr）相同的拓扑结构,且具有很好的热稳定性。Hf-FUM和Hf-BDC的结构在水中能够保持稳定,而Hf-BPDC在水中会发生降解。同时,具有最小孔尺寸的Hf-FUM材料对CO₂/N₂以及CO₂/CH₄体系具有最好的分离性能。这为以后设计用于CO₂分离的新型纳微结构材料提供了参考依据。