MOFs衍生的多孔纳米碳宏观体构建及其水处理性能的影响因素研究

The removal of pollutants from water by metal-organic framework (MOFs) is a promising solution to the problem of increasing water pollution. However, there are two important problems limiting their application. One is that MOFs may collapse in aqueous solution, and the other one is that, as nano powder, MOFs is difficult to recover and reuse. In our previous studies, we prepared a MOF/polymer monolith by the ice-templating method, and the monolith showed high adsorption capability and convenient recovery. Simultaneously, we found that the addition of MOFs to polymer can effectively prevent polymer from obvious shrink during carbonization and can reinforce the formed porous carbon monolith. However, it is still ambiguous that the rules by which MOFs will abide in the process of carbonization, and how the carbonized MOFs reinforce the porous carbon monolith. So, in the project we will carry out: the preparation and carbonization of MOFs and MOFs/polymer monolith, the stability research of as-prepared samples and evaluation of the pollutants adsorption capacity of the samples from waste water. Based on the studies, it is expected to find out the influence of carbonization process on properties of the formed samples and the rules that the carbonized MOFs reinforce porous carbon monolith. In addition, the relationship between adsorption capacity and structures will be concluded. The results of the project will provide a practical technical scheme for sewage treatment.

金属-有机骨架（MOFs）作为极具前景的水处理吸附剂，存在两个问题限制其应用：一、在水中可能出现晶体结构坍塌；二、作为纳米粉体，回收困难。针对一，可将MOFs转化为纳米多孔碳，以提高其化学稳定性；针对二，可将MOFs组装成宏观结构，以实现便捷回收。申请人通过冰模板法制备了MOF/聚合物块体，其碳化得到了具有分级孔结构的三维多孔碳宏观体，实现了稳定、高效的吸附和便捷的回收。同时发现MOFs在聚合物基体中一起碳化，能防止聚合物碳化收缩并增强宏观体的机械强度。然而，不同MOFs的碳化规律及碳化的MOFs增强碳宏观体的机理仍不清晰。为此，拟开展：MOFs及MOFs/聚合物块体制备、碳化，产物稳定性，产物吸附水中污染物等研究。旨在揭示MOFs衍生碳材料结构、性能的调控因素及机理，碳化的MOFs增强碳宏观体的机理和规律，建立结构与吸附性能之间的联系，为制备高效、稳定、易回收的水处理吸附剂提供优选方案。

废水再生是解决全球水资源危机的重要途经之一。吸附法是一种经济、高效、简单的废水处理方法。金属-有机骨架（MOF）材料作为极具前景的水处理吸附剂，在多种废水处理中表现出优异的性能。然而，部分MOF材料在溶液中的化学稳定性差，以及其粉末状态导致的回收困难限制了其规模化应用。为此，本项目合成了多种MOF材料并将其与聚合物复合制备了MOF/聚合物复合块体。进一步在惰性气氛中将MOF及MOF/聚合物转化成了衍生的碳纳米颗粒和多孔碳块体材料。对得到的材料进行了微观结构、表面化学、孔结构特征、染料吸附性能等评价。结果表明通过控制原料中2-甲基咪唑的比例能够调控生成的ZIF-8颗粒的尺寸。将ZIF-8，UiO-66在惰性气氛中碳化能得到与其母体形貌类似的碳颗粒材料。通过冰模板法可以方便地制备出MOF/聚合物复合块体材料，且冰晶在形成的过程中能使MOF颗粒和高分子链重新排布，冰晶冻干后能在材料中形成大孔结构。静电纺丝的方法也易于实现MOF和高聚物的复合。将MOF/聚合物块体在惰性气氛中碳化能得到具有分级孔结构的多孔碳块体材料，且MOF材料的加入能够降低聚合物在碳化过程中体积的收缩。制备的MOF、MOF/聚合物及它们的衍生碳材料对废水中的染料分子能有效吸附去除。ZIF-8衍生的碳材料对亚甲基蓝的吸附能力能达到1461.988 mg g–1，UiO-66/chitosan复合块体对刚果红的吸附容量能达到246.91 mg g–1。MOF/聚合物复合块体及其衍生碳块体材料相比于MOF及其衍生的碳颗粒材料更易于回收，能大大加快水处理的进程。