“螺吡喃-冠醚”分子探针可视化高效提锂机制研究

Lithium is an important energy strategic metal, which plays an important role in national defense and energy development. The extraction of lithium from salt lake brine is an important supply channel of lithium resources. However, it is difficult to utilize the lithium from the salt lake brine which is a multi-salt coexistence system with high ionic strength. In view of the properties of the complexing ability of spiropyran compounds with metal ions and the properties of light activated open or closed-loop of spiropyran, as well as the visualization advantage of optical probe, the "spiropyran-crown ether" optical probe with specific recognition for lithium ion will be constructed by modifying the spiropyran molecule with 12-crown -4-ether or 14-crown-4. The visible capture and release of lithium ion can be realized by controlling the open-loop or closed-loop of spiropyran. In this project, the relationship between the structures of the "spiropyran-crown ether" functional organic molecule and the complexing abilities with lithium will be studied. The UV-Visible spectroscopy and the fluorescent spectroscopy will be used to study the visual capture and release properties of lithium by regulating the open-loop or closed-loop of spiropyran with light. On the basis of this, a highly stable "spiropyran-crown ether" membrane material will be established, which will be applied to selectively extract trace lithium visually from salt lake brine with high ionic strength. The project attempts to use optical probe to the capture and separation of lithium ion of optical inert, and the separation process is visualized and highly efficient. It also provides insight for the efficient extraction of other rare metal ions.

本项目针对高离子强度卤水体系锂资源分离富集难度大的问题，鉴于螺吡喃分子光致开关的性质和络合金属离子的能力，结合其分子探针可视化的优势，拟通过对螺吡喃功能化修饰构筑能够特异识别锂离子的“螺吡喃-冠醚”有机框架材料，利用光调控“开-闭环”实现对锂离子的可视化俘获和释放。重点研究“螺吡喃-冠醚”功能有机分子的结构和锂离子络合性能之间的关系，提高分子探针对锂离子的特异识别能力；采用紫外、荧光等光谱学手段和体系颜色改变，研究光调控螺吡喃“开-闭”环对锂离子的可视化俘获和释放性能。在此基础上，构建高稳定性“螺吡喃-冠醚”聚合物复合膜材料，完成高离子强度盐湖卤水复杂体系中微量锂离子的可视化高效提取和复合膜材料的循环利用。本项目尝试将分子探针用于光学惰性金属锂离子的捕获和分离，实现提取过程的可视化、高效化。该方法的建立，也为其他稀有金属离子的有效提取提供了可以借鉴的新思路。

针对高离子强度卤水体系锂资源分离富集难度大的问题，本项目设计合成了具有光响应可逆“开-闭”环特性的“螺吡喃-冠醚”新型提锂分子，研究了其光响应特性、循环稳定性、对锂离子的选择性以及可视化提锂性能。在此基础上，通过一步相转化法将“螺吡喃-冠醚”分子与聚偏二氟乙烯（PVDF）共混，制备了具有光响应特性的多级孔复合微球和多孔聚合物复合膜，以复合微球为吸附剂，研究了其对离子的吸附动力学和热力学，揭示吸附提锂机制。通过对聚合物复合膜外加电场，构筑了电吸附强化提锂体系，考察了外界因素的影响规律。此外，项目还扩展研究了内相限域有“螺吡喃-冠醚”分子的O/W型光响应Pickering乳液提锂新体系，优化了乳液制备工艺，以该乳液为介质强化锂离子在油水界面传质，实现了锂离子的高效高选择性提取。.项目实施期间发表论文18篇，其中SCI收录11篇，申请专利6项，授权3项，发布山西省地方标准1项，举办学术会议2次，培养出站博士后1名，博士研究生1名，硕士研究生7名。