具有高效氢离子传递位点的阳离子交换膜构筑及其透酸阻隔重金属性能研究

The low permselectivity of cation exchange membrane for proton and heavy metal ions is the key problem for the application of electrodialysis technology in the recycling of industrial spent acid. To break the trade-off effect between the proton permeability and permselectivity, the structure-function relationship of the separation performance and structures of sulfonated poly(ether ether ketone) with pendant tertiary amine groups or zwitterion will be investigated. The sulfonated poly(ether ether ketone) with pendant tertiary amine groups will be synthesized by a controllable one pot reaction with high efficiency. Phosphate or carboxyl group will be further introduced into polymer based on the quaternization of tertiary amine groups forming zwitterion. The proton permeability are believed to be accelerated by the high-efficiency proton transfer sites based on the tertiary amine groups, phosphate or carboxyl group of the zwitterion. The heavy metal leakage could be reduced by the quaternary ammonium of zwitterion or the protonated tertiary amine groups due to the Donnan repulsion effect. The effect of functional groups on the properties and performance of the membrane will be studied. The relationship between the polymer structure and seperation performance of proton and heavy metal ions will be investigated. We believe that the proposed investigations will give us the insight for cation exchange membranes design and preparation.

阳离子交换膜较低的氢离子/重金属离子选择性成为电渗析法资源化废酸面临的难题，而解决氢离子选择性和渗透性之间此升彼降的矛盾是制备高性能阳离子交换膜的关键。本项目拟通过在阳离子交换膜中引入功能基团(如叔胺、两性离子)，构筑高效氢离子传递位点和道南排斥效应，实现氢离子渗透性和选择性的同时提高。采用高效、可控的羰基二咪唑活化磺酸基转化为磺酰胺的反应，一锅法制备叔胺功能化磺化聚醚醚酮，进而将叔胺季铵化，引入磷酸基或羧基，构成两性离子。叔胺、磷酸基或羧基构成高效氢离子传递位点，促进氢离子的传输；质子化的叔胺或季铵通过道南排斥效应阻隔重金属离子。研究功能基团种类和含量对膜分离性能的影响规律，揭示叔胺和酸性基团对氢离子传输作用机制，阐明道南排斥效应对氢离子/重金属离子选择性的影响规律。因此，本项目的研究为高性能阳离子交换膜的制备提供新的设计思路和理论依据。

选择性电渗析可用于废酸中酸和有价金属的分离回收，高选择性阳膜的制备近年来备受关注。本项目针对阳膜的氢离子渗透性和选择性之间此升彼降的矛盾，研究阳膜中叔胺、季铵、化学交联或刚性链聚合物等结构对膜性能的影响规律及作用机制。本项目以磺化聚醚醚酮为阳膜基材，(1)通过化学改性制备叔胺功能化磺化聚醚醚酮阳膜，研究了叔胺基团的结构和含量对膜性能的影响规律及作用机制。其中，咪唑基团功能化磺化聚醚醚酮阳膜具有与磺化聚醚醚酮阳膜相同的氢离子通量，H+/Fe2+渗透选择性提升至磺化聚醚醚酮阳膜的3倍；进而，添加交联剂构建化学交联膜，其渗透选择性是磺化聚醚醚酮阳膜的10倍。(2)在磺化聚醚醚酮中共混含胺基刚性链聚合物(Troger's base聚合物, TB)，并探究了TB季铵化对膜性能的影响。磺化聚醚醚酮中共混TB和季铵化度为5%的TB，膜的H+/Fe2+渗透选择性分别达285和500，而H+通量均无明显降低；(3)采用“点击化学”反应在聚砜侧链接枝不同含量的季铵基团和羧基，研究离子化聚砜及季铵基团含量对磺化聚醚醚酮阳膜分离性能的影响。基于以上研究，明晰了叔胺、季铵和共价交联等结构对膜性能的影响，探明了含胺基刚性链聚合物对磺酸型阳膜微观结构和性能的影响，可为进一步制备新型膜材料和高性能阳膜提供理论支撑。在本项目的支持下，已在Journal of Membrane Science，Separation and Purification Technology等期刊发表期发表论文6篇，授权发明专利1项，获省级科技进步一等奖1项（排名：4/10），部分研究成果在投稿中。