金属有机骨架离子交换剂富集分离重金属离子研究

The preconcentration and separation of heavy metal ions including mercury (Hg), cadmium (Cd), and arsenic (As) et al. is not only one of the important research topics in environmental protections, but also beneficial to the recycling of heavy metals as industrial resources. Among various technologies developed for heavy metal ions preconcentration and separation, ion exchange approach holds great promise. A variety of porous materials as ion exchangers have been developed and tested for this purpose. However, conventional ion exchangers suffer from some drawbacks, such as difficult modification and low tunability of the cavities, which usually lead to low adsorption capacity and selectivity of them towards heavy metal ions, thereby limiting their applications in this field. Recently, metal-organic frameworks (MOFs), a new family of nanoporous materials, have shown great potential applications in heavy metal ion preconcentration and separation, due to their well-defined porous structures, high surface areas, tunable pore sizes, and easily desired chemical functionalities. Based on our previous works in the related topics, this project will systematically explore the effects of the micro-structures of MOFs on the preconcentration and separation of heavy metal ions including mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), and arsenic (As) ions, through the combination of molecular simulations and experimental techniques. Molecular simulations are firstly employed to screen the effects of various functional groups on the adsorption and separation of these heavy metal ions. Based on the simulation results, a series of MOFs with superior functional groups but different pore properties are designed and synthesized, and their performances on heavy metal ion preconcentration and separation are investigated in detail. Results from this project not only direct the exploration of MOFs as ion exchanger and adsorbent for efficient preconcentration and separation of heavy metal ions, but also benefit the design and synthesis of other porous materials for this application.

重金属离子的富集分离不仅是当今环保领域的重要课题，也对重金属资源循环利用具有重要意义。离子交换法是富集分离重金属离子的重要手段。传统多孔离子交换剂因其结构和性质的可控调节性较低，难以针对目标离子的特性进行有效优化，因而对重金属离子的吸附量和选择性较低，分离效果较差。MOFs作为一类新兴多孔材料，具有比表面积大、结构与孔性质易调等优势，在重金属富集分离上具有极大应用潜力。由于MOFs结构复杂且多样、活性基团种类繁多，纯粹采用实验方法很难对其重金属离子富集分离性能进行系统研究。基于此，本项目拟在申请人近年科研工作的基础上，充分发挥计算模拟和实验结合的优势，利用计算模拟筛选出对某些重金属离子（汞、镉、铅、铬、砷）具有选择性分离功效的活性基团和交换离子，指导实验有目的、有针对性的合成或修饰MOFs，通过调节MOFs的孔结构、表面功能团及活性点等，设计制备对以上离子具有高分离富集性能的新离子交换剂。

重金属离子（如：汞、镉、砷等）的富集分离是当今环保领域的重要研究课题。MOFs作为一类新兴多孔材料，具有比表面积大、结构与孔性易调等优势，在重金属富集分离上具有极大应用潜力。本项目从配体和金属节点设计入手，设计合成了系列具有不同孔腔大小、形状和特定官能团的MOFs，并对其重金属吸附分离性能进行了研究。结果发现由后修饰功能化得到的两例巯基化MOFs，UiO-66-SH和MIL-101-SH均具有较好的吸附水溶液中Hg离子的能力，其中UiO-66-SH对汞离子最大吸附量可达490.98mg/g。通过计算吸附参数，初步判断此吸附过程遵循Langmuir吸附机理。此外，UiO-66-SH和MIL-101-SH均对汞离子表现出良好的吸附选择性和重复利用性。这些材料在工业污水处理领域具有潜在应用前景。在本项目资助下，相关研究结果共发表SCI 收录论文4 篇（全部为一区论文），授权中国发明专利1 项，另有3项处于申请状态。项目执行期内培养硕士研究生5名，1名硕士生的毕业论文获“北京工业大学优秀硕士学位论文”。