碳基电活性离子选择渗透膜制备及其双电层-脉冲电位耦合离子传递机制

China is rich in salt lake brine resources; however, the coexistence of multiple ions seriously affects efficient separation of high-value-added ions. The efficient separation and recovery of rare and precious metal ions from salt lake brine with high selectivity are urgently required for effective utilization of salt lake resources. Taking the selective separation of cesium and lithium ions from salt lake brine as the objective, a novel electroactive ion selective permeation membrane (EIPM) system based on electrical double layer-pulse potential coupling (EDL-PPC) ion transport mechanism is designed to perform selective, continuous and efficient separation of target ion under the multi-ions coexistence condition. Electroactive functional groups with specific recognition ability to the cesium or lithium ion are grafted onto the surface of carbon nanotubes (CNTs) or graphene substrates in order to build an affinity system for target ion, and the carbon-based EIPM electrode is prepared by pressure filtering technique of fractional steps. The EDL will enrich metal ions reversibly on the surface of the three-dimensional porous electrode, and the diffusion selectivity and the adsorptive selectivity of various ions in the membrane can be regulated by pulse potential method. Combining the directed migration of ions caused by external electric field with step potential oscillation with high frequency, the selective separation of the target ions can be realized. The research focus on the interaction between target ions with electroactive group in the EIPM, reversible adsorption/desorption mechanism of target ions, the confined ions transfer mechanism, the relationship between pulse operational parameters and membrane structure, and ion adsorption/diffusion performance. As such, a theoretical basis for the industrial application of multi-target ions separation from salt lake brine with this novel EIPM system is expected to be provided.

盐湖卤水资源丰富，然而多离子共存严重影响其分离效果，特别是稀有贵金属离子的选择性高效分离成为盐湖资源有效利用的关键。本项目以铯、锂离子的选择性分离为目标，设计了一种基于双电层-脉冲电位耦合电控离子传输机制的新型电活性离子选择渗透膜（EIPM）系统，实现多离子共存条件下目标离子的选择性分离。将对铯或锂离子有专一识别能力的电活性功能基元嫁接于碳纳米管或石墨烯基体，构建目标离子的亲和作用体系，并通过分步压滤技术制备碳基EIPM；利用膜电极表面的双电层快速、可逆富集金属离子，并通过脉冲电位调控不同离子在膜中的扩散选择性和吸附选择性，结合外部电场对离子的定向迁移作用和高频阶梯电势振荡技术，实现目标离子的选择性分离。重点研究EIPM中活性基元与目标离子间的相互作用、目标离子可逆吸/脱附及限域离子传递机制、脉冲参数与膜结构以及离子吸附/扩散性能之间关系，为盐湖卤水中多目标离子的高效电控分离提供理论依据。

盐湖卤水资源丰富，然而多离子共存严重影响其分离效果，特别是稀有贵金属离子的选择性高效分离成为盐湖资源有效利用的关键。本项目以盐湖卤水中的Cs、Li离子的同步分离为目标，研发了多种基于双电层-脉冲电位耦合（EDL-PP）离子传输机制的电活性离子选择渗透膜（ESIPM）分离新材料及新工艺。制备出了对Cs或Li离子有专一识别能力的电活性功能膜电极。通过搭建的多套新型的电控离子选择渗透分离膜系统实现了盐湖卤水体系中目标离子连续高效分离回收，掌握了调控ESIPM活性功能基元分布的方法，获得了双电层-脉冲电位耦合耦合条件下目标离子选择性传输及分离的过程机理与强化途径，探明了脉冲电位、槽电压等操作参数对离子传递性能的影响和作用机制。重点研究了EIPM中活性基元与目标离子间的相互作用、目标离子可逆吸/脱附机制、界面电荷传递、脉冲参数与膜结构-离子吸附/扩散性能之间关系，为盐湖卤水中多目标离子的高效电控膜分离提供了理论依据。