基于二维层状过渡金属硫化物的复合体系构筑及其对重金属环境污染物的响应与富集研究

High-efficiency capture and removal of highly toxic heavy metal ions from aquatic system is of great significance for the safeguard of human health and the protection of environment. At present, effective reduction of heavy metal ions down to the acceptable levels of drinking water standard (trace levels, < several ppb) remains a key scientific challenge in wastewater and drinking water treatment. Taking into consideration that two-dimensional (2D) layered transition metal dichalcogenides (TMDs) possess intrinsically sulfur-rich characteristic, unique 2D lamellar structure, higher surface-to-volume ratio, expandable interlayer spacing and the characteristic that various cations could be intercalated into their interlayers, we hypothesize that these compounds should be promising to be applied to the efficient removal of highly toxic heavy metal ions from aquatic system. However, the practical application of 2D layered TMDs in the important field of heavy metal ions removal has been limited by several limitations of these materials, including the lack of sufficient available active sites, narrow interlayer spacing which does not admit heavy metal ions to their interior spaces, and the aggregation of layers in aqueous solutions. With this in mind, this project aims to realize the application of 2D layered TMDs in the important field of heavy metal ions removal, by designing and manipulating the composition and structure of 2D layered TMDs, and constructing functional composite system by using 2D layered TMDs. The interaction mechanism between heavy metal ions and 2D layered TMDs will also be probed and illuminated. This project will not only exploit advanced functional system for remediation of heavy metal ions polluted water, but also promote the applications of 2D layered TMDs in the important field of environmental remediation and provide theoretical foundation for the future development of new adsorbents for the capture and removal of heavy metal ions.

将高毒性的重金属离子从水中分离和去除，对于保护环境、保障人类健康有重要意义。目前，将重金属离子浓度降低到饮用水标准允许的浓度以下仍是一个富有挑战性的科学难题。二维层状过渡金属硫化物富含大量的硫原子、大的表面积-体积比、独特的层状结构、可扩展的层间距、层间可嵌入阳离子等特性，使得其有潜质用于重金属离子的高效富集和分离。但是，其暴露的活性位点数目少、层间距小不利于重金属离子进入、片层在水溶液中易于聚集等缺点限制了其在重金属离子富集和分离方面的应用。基于此，本项目着重于对二维层状过渡金属硫化物的组成和结构进行设计和调控，同时构筑基于二维层状过渡金属硫化物的功能化复合体系，以实现高效的重金属离子富集与分离；并研究二维层状过渡金属硫化物对重金属离子的作用机制。本项目的研究有利于拓展二维层状过渡金属硫化物在环境领域的应用，并为设计新型高效的重金属离子富集和分离体系提供理论依据。

将高毒性的重金属离子从水中分离和去除，对于保护环境、保障人类健康有重要意义。本项目基于二维层状过渡金属硫化物和层状双金属氢氧化物独特的结构和组成特点，针对这些材料在重金属离子去除领域的优势和局限性，对其进行组成与结构的调控和功能化修饰，以实现有效结合位点的最大化暴露，构筑高效的重金属离子富集与分离体系，并阐明重金属离子在其表/界面的作用机制，探索层状过渡金属硫化物等二维材料在重金属离子去除领域的应用前景。.基于项目的实施，共构筑了三种具有重金属离子特异性识别能力和选择性的基于二维层状过渡金属硫族化合物的功能化复合体系：①二硫化钼/天然纤维素复合材料; ②二硫化钼/碳气凝胶复合体系; ③二硒化钼纳米花；这几种体系对铅、汞等重金属离子具有较强的结合作用，有希望用于高毒性的重金属离子的高效去除。两种基于二硫化钼的功能化复合三维体系对汞离子最大吸附容量分别达到1206 mg g-1和1562 mg g-1。另外，这两种体系三维结构的特点有望改善传统的微纳米结构的吸附剂在使用以后分离和回收困难的缺点。二硒化钼纳米花对Hg2+（222-952 mg g-1）和Pb2+（148-218 mg g-1）有高的去除效率(99%以上)。机理研究表明Se原子是Hg2+的结合位点，而Pb2+主要是与Mo（IV）被氧化形成的钼酸根离子形成钼酸铅沉淀。.在项目执行的过程中，对项目的研究内容进行了衍生，构筑了两种功能化的二维层状双金属氢氧化物体系（LDHs）和一种富含氨基和酚羟基的三维多孔气凝胶：④植酸 (PA) 功能化修饰的LDHs材料；⑤硫代钼酸根功能化的LDHs/细菌纤维素复合体系；⑥聚己二胺-单宁酸功能化修饰的细菌纤维素气凝胶。两种功能化的LDHs体系分别实现了对镉离子和汞离子的高效富集和分离；聚己二胺-单宁酸功能化修饰的细菌纤维素气凝胶对六价铬具有高效的固定、还原以及回收作用（最大容量377-535 mg g-1）。

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