稀有金属离子印迹复合膜的可控制备及其选择性分离特性与机理

Based on the technologies of metal ion imprinted polymer and free-radical graft polymerization of functional monomer onto a porous ceramic membrane, the novel imprinted ceramic composite membranes with the high selectivity for the target rare metal ions will be prepared in this applied project. The separation characterization and mechanism of the membranes will also be studied. The main contents of the project are as follows: According to the characteristics of the functional monomers complexed with the template ions, the functional monomers are selected. Then, the monomers of rare metal ion imprinted polymers are synthesized controllably. Meanwhile, the complexation characteristics of the functional monomers with rare metal ions, like binding sites, interaction modes and chemical bonds, are studied to obtain the mechanisms of complexation reactions by using a series of spectrographic technologies such as nuclear magnetic resonance, fourier transform infrared spectroscopy and x-ray diffraction. Then, free-radical graft polymerizations of the monomers of rare metal ion imprinted polymers onto the modified ceramic membranes are studied. Effects of various parameters on the structure and performance of the composite membranes are investigated in detail. The binding modes of the membranes are studied by a series of spectrographic technologies. In order to remove efficiently the template ions in the membranes, the washing modes are investigated to obtain the optimum washing parameters. The surface morphology and structure of the membranes are studied by using the electron microscopes. Then, the membranes are used to separate selectively the target rare metal ions. Based on the recognition behaviors of the membranes with rare metal ions, the kinetics and thermodynamics models are built. Further, the recognition mechanisms of the membranes with rare metal ions are obtained by using the molecular modeling and spectrographic technologies. Finally, the regeneration behaviors of the membranes are studied, and the capacities of the recycling membranes are examined. When this project is achieved, the new technology and materials will be put forward to extract rare metal ions simply, economically and efficiently. The work has a very significant role to strengthen the national defense and improve the efficiency of resource utilization.

本项目提出以离子印迹和陶瓷膜接枝为基础，制备一种新型的高度选择目标稀有金属离子的印迹陶瓷复合膜，探索复合膜分离特性和机理，拟研究内容涉及：筛选出功能单体，与模板稀有金属离子配位合成印迹聚合物单体，以核磁共振、傅立叶红外及X射线衍射等谱学技术研究稀有金属离子与功能单体的结合位点、作用模式及成键情况；以印迹聚合物单体在已改性陶瓷膜表面接枝聚合，考察各参数对复合膜结构和性能的影响，利用谱学技术研究接枝及印迹过程的结合模式；探索复合膜模板离子洗脱规律，优化洗脱参数，以电子显微镜研究复合膜形貌和结构；研究复合膜对目标稀有金属离子的识别行为，建立复合膜识别动力学和热力学模型，采用分子模拟和谱学技术等手段，揭示复合膜与稀有金属离子的识别机制；研究复合膜再生行为，评价其循环使用效能。通过本项目研究，为稀有金属的高效富集、分离和回收提供新技术与新材料，对加强国防建设和提高资源利用效率具有重要意义。

基于国内稀有金属的分离水平有待进一步提升，本项目以离子印迹、表面接枝和表面偏析为基础，制备了Pd(II)、Pt(IV)、Ru(III)、W(VI)、Mo(VI)等稀有金属离子印迹膜，探索了印迹膜的分离特性和机理，研究了印迹膜对稀有金属离子的识别行为，建立了印迹膜吸附动力学和热力学模型，研究了印迹膜再生行为，评价了循环使用效能，主要涉及：针对Pd(II)离子体系，制备了新型聚(4-乙烯基吡啶)-b-聚砜-b-聚(4-乙烯基吡啶)/聚砜共混膜，该膜对Pd(II)具有良好截留性能和较高选择性(分离系数Pd/Cu为41.92，Pd/Ni为97.81)；为了选择性分离Pt(IV)，合成了两亲性聚甲基丙烯酸甲酯-b-聚4-乙烯基吡啶（PMMA-b-P4VP），制备了PMMA-b-P4VP/PVDF共混膜，研究了各因素对共混膜结构和性能的影响，以高P4VP含量的共聚物为功能聚合物、N,N-二甲基乙酰胺为溶剂、30wt％PMMA-b-P4VP/PVDF比率制备的共混膜具有优异性能，印迹膜对Pt(IV)具有高吸附容量和选择性，Pt(IV)/Cu(II)和Pt(IV)/Ni(II)选择性系数分别为27.66和77.16，此外，印迹膜具有良好的再生性能；针对Ru(III)离子溶液体系，以聚甲基丙烯酸甲酯-co-聚甲基丙烯酸羟乙酯与PVDF共混，成功地制备了印迹膜（Ru(III)-IIM），P(MMA-HEMA)使得Ru(III)-IIM的亲水性显著提高，pH值为2.0时达到最大吸附量42.31mg g-1，Ru(III)-IIM对Ru(III)具有较高选择性，且重复利用性能良好；为了选择性分离W(VI)、Mo(VI)，以陶瓷膜作为基材，通过原位水解引入活性二氧化硅层，以W(VI)、Mo(VI)离子为模板离子、1-乙烯基咪唑（VI）为功能单体、1,6-二溴己烷为交联剂，采用表面离子印迹和接枝聚合技术制备了W(VI)、Mo(VI)印迹陶瓷膜，该膜具有良好吸附能力，Mo(VI)对W(VI)的选择性系数高达7.48，IIP-PVI/CM对W(VI)和Mo(VI)的吸附饱和时间分别为24和47 min，吸附容量分别为0.163和0.672 mmol/100g，选择性分离效果良好。通过本项目研究，也许可以为稀有金属的分离、回收提供新思路。目前已发表研究论文14篇，申请发明专利4项，毕业研究生6名。