面向盐湖卤水锂提取的耐酸、耐溶剂聚醚醚酮膜的结构与性能调控

This proposal aims to explore the control of the structure and performance of the key membrane material for the extraction of lithium-ion from salt-lake brine with high ratio of magnesium/lithium(Mg/Li) in a membrane contactor extraction process. Based on the immersion precipitation method, poly(ether ether ketone) (PEEK) membranes are prepared using methanesulfonic acid/sulphuric acid as the solvent. The thermodynamics and kinetics of the phase separation are systematically investigated. The crystallization behavior of PEEK polymer in the solution as well as in the demixing process is analyzed. To reduce the mass transfer resistance, co-casting technique is used to control the sub-layer morphology. Moreover, SPEEK is introduced into the PEEK solution system to prepare a cationic porous membrane for improvement of the lithium diffusion. The lithium transport model in the diffusion-reaction coupling process in a stable mode is used for comparing the mass transport resistance of the membrane in relation to the extraction or stripping reaction as well as the concentration polarization. The results from this work will provide guidelines for the development of the crucial strong acid/solvent resistant and low mass transfer resistance membrane for the lithium separation. It also provides solid fundamental basis for structure control of semi-crystalline polymer membrane in an immersion precipitation method.

本项目面向高镁低锂盐湖卤水锂离子的提取，研究耐酸、耐溶剂、低传质阻力的膜萃取材料的结构和性能的关系，解决高分子/酸溶剂体系下的相分离机理及面向离子传输的孔结构调控关键问题。项目以聚醚醚酮(PEEK)为核心材料，硫酸/甲磺酸为溶剂，采用浸没沉淀法，通过相分离热力学和动力学的研究，为酸溶剂体系中膜结构调控提供理论依据。研究膜材料的收缩与结晶度的作用关系，阐述膜材料的收缩机理；通过双层刮膜法研究双层铸膜液相互作用规律及其对PEEK膜结构及传质的影响，构建低传质阻力膜结构；通过在PEEK中引入荷电高分子SPEEK优化结构与传质性能，提高离子传质效率。项目还将研究锂离子在扩散-反应耦合过程中传质的特点，建立稳态传质模型，为各工艺段中的传质优化提供量化依据。研究将形成新的耐强酸、耐溶剂、低传质阻力膜材料，为高镁锂比卤水锂离子提取技术的发展提供膜材料及理论基础。

本项目面向高镁低锂盐湖卤水锂离子的提取，研究了耐酸、耐溶剂、低传质阻力的膜萃取材料的结构和性能的关系，解决高分子/酸溶剂体系下的相分离机理及面向离子传输的孔结构调控关键问题。本工作以聚醚醚酮(PEEK)为核心材料，浓硫酸(SA)/甲磺酸(MSA)为溶剂，采用浸没沉淀法制备PEEK膜，进行了相分离热力学和动力学的系统研究，探索了酸溶剂体系下的相分离机理，此外还重点研究了磺化PEEK/PEEK的共混膜的制备，通过引入荷电高分子，优化了膜结构与锂离子传质性能，其结果为酸溶剂体系中膜结构调控提供了理论依据。项目工作还研究了膜材料的收缩与结晶度的作用关系，阐述了膜材料的收缩机理；本项目还研究了膜萃取中锂离子传质的特点，并结合无纺布支撑的复合膜的制备对其传质进行了优化。研究结果形成了新的耐强酸、耐溶剂、低传质阻力膜材料，为高镁锂比卤水锂离子提取技术的发展提供膜材料及理论基础。