多元混合溶液（例如海水、人体血液以及工业废水）中选择性获取特定元素的离子具有非常重要的意义，例如海水中镁元素的提取、盐湖中锂元素的分离。从纳米尺度的角度研究直接物理分离混合溶液中不同离子，是实现离子高选择性分离的一条新的道路。具有纳米受限空间的碳基材料，例如碳纳米管、石墨烯膜，被普遍认为在离子选择性分离上具有潜力。在溶液中，离子与碳基材料表面富含π电子的六元芳环结构之间存在一个非常强的相互作用——水合离子-π相互作用，目前已经在许多方面发挥了至关重要的作用。本项目研究基于溶液中不同离子在纳米受限碳基材料表面的水合离子-π相互作用强度的差异，使用碳纳米管进行混合溶液中不同离子的选择性吸附区分，通过实验直接观测碳纳米管中的离子选择性吸附情况。并尝试将理论研究方法和得到的结果应用到离子选择性分离相关的元素提取、生物仿生、微纳器件制备等一系列研究中。

Selective extraction of specific ion in mixed solutions (e.g. seawater, human blood and industrial wastewater) is of great significance, e.g. the extraction of magnesium from seawater and the separation of lithium from salt lakes. Studying the direct separation of different ions by physical methods from the point of view at nanometer scale pave a new way to the high selective separation of ions from the mixed solution. Nano-confined Carbon-based materials, e.g. carbon nanotubes and graphene membranes, are widely regarded as showing great potential for the selective ionic selectivity. There is a very strong interaction between hydrated ions and the π-electron-rich aromatic rings on the surface of carbon-based materials in aqueous solution, ¬¬hydrated ion-π interaction, which plays a vital role in many aspects. This project study on using carbon nanotubes to selectively adsorb specific ion in mixed solutions, based on the difference in hydrated ion-π interactions of different ions. And the selective adsorption of ions in carbon nanotubes can be directly observed by experiments. The theoretical methods and experimental results are applied to a series of studies related to ion selective separation, e.g. element extraction, biomimetic chemistry and designing micro/nano devices.