电势振荡锂离子筛分膜的有序组装及离子传递双通道耦合传质机制

Because more than 80% of the lithium resources in the world mainly exist in the brine, groundwater and seawater, the key for the development of lithium resources is to develop the appropriate ion separation method having the high selectivity and the anti-interference ability of the coexisting ions. In this research, a potential responsive smart ion sieve membrane with the parallel ion channels for lithium transport will be fabricated by using the vertical nanowire arrays of the conductive polypyrrole as the template. The oxidative polymerization of the pyrrole monomers and the electrostatic self-assembly of the suspended spinel manganese dioxide nanoparticles are carried out alternately under the pulse potential method for the growth of the ordered hybrid membrane. The strength of affinity between the electroactive ion exchange functional elements and the target ions can be adjusted by applying the pulse potential. On this basis, the ion permeability of the membrane can be improved with the help of the external electric field, which induces a potential oscillation ionic sieving effect. Furthermore, the improvement of the ion selectivity of the membrane can also be realized by the use of the different affinity between the functional groups of the dopants and the target ions and the confinement effect of the crystal structure of the manganese dioxide. Such a novel approach will result in the breakthrough of the trade-off effect between permeability and selectivity. The research focuses on the formation mechanism of the organic-inorganic hybrid membranes and the precise regulation mechanism of the micro-structure of the functional elements, and reveals the relationship between the structure of the membrane and its permselectivity for the target ions. A coupling mass transport mechanism for describing the ion transport in the parallel ion channels constructed respectively by the organic and inorganic components and the interface zone of the two phases will be investigated and the related dynamic model of ion transport will be constructed. It is expected that a theoretical basis could be provided for the industrial application of such a novel potential oscillation smart lithium ion sieve membrane based on this research.

全球锂资源80%以上蕴藏于水相体系，克服多离子干扰、实现高选择性分离是锂资源高效开发和回收的关键。本项目以导电聚吡咯纳米线阵列为自模板，通过脉冲电位控制吡咯单体分步氧化聚合，并与尖晶石型二氧化锰悬浮纳米颗粒通过静电自组装逐层有序生长，构建具有离子传递双通道的电位响应型锂离子智能筛分膜。通过施加阶跃电位智能调控膜内电活性离子交换功能基元与目标离子的亲和力强弱，并耦合外加定向电场诱发电势振荡离子筛分效应提高离子渗透通量；依据不同离子与掺杂剂携带官能团的亲和力差异及离子印迹型二氧化锰的晶格限域效应，优化离子传递双通道的选择性，突破trade-off效应。重点研究有机/无机杂化成膜机制及电活性功能基元微结构的精细调控机理、揭示膜结构与离子选择渗透性能的构效关系，阐明离子在有机、无机两组分构筑的双通道及相界面间的耦合传质机理，建立离子传递动力学模型，为新型电势振荡锂离子筛分膜的工业应用提供理论依据。

电势振荡离子筛分膜（POISM）分离作为一种新型的离子分离技术，具有选择性高、分离速率快、可连续运行等诸多优点。将具备电位响应功能的电控离子交换材料制备成膜，通过脉冲电位可控调节膜内电活性离子交换功能基元与目标离子的亲和力强弱，同时耦合外加电场驱动离子定向迁移，实现目标离子的高选择性快速分离。.本项目以水相体系中锂离子的分离为目标，将尖晶石型Li-Mn-O离子筛与高导电性的新型碳材料复合，制备出了具备选择性高、稳定性好、离子传递速率快的新型POISM。掌握了POISM的纳、微结构调控手段及其构效关系，探索出了锂离子在POISM内的传递机理。在此基础上，开发了能够连续运行的POISM分离系统，优化了该系统的操作参数，并构建了离子传递模型，为新型POISM分离技术的工业应用提供了理论依据。.此外，为拓展POISM分离系统的应用领域，针对不同目标离子的结构特性，通过调控POISM的结构和形貌，相继开发出一系列具有高选择性分离功能的新型电活性离子分离膜材料，为该技术在盐湖资源综合开发、重金属污水治理等领域的应用奠定了基础。