同轴电纺制备增强型芳香聚酰胺超细中空纤维荷电纳滤膜及其分离特性研究

Water pollution is getting worse around the world.Membrane seperation is becoming one of the most important technologies for water recycle applications. In this project, we plan to develop a new type of carbon nanotubes/aromatic polyamide ultrafine hollow fibre composite nanofiltration membrane by synergizing the excellent reinforcement properties and electrical charge effect of carbon nanotubes with the high specific surface area of coaxial electrospun ultrafine hollow fiber membrane. The project will focus on the method to build and manipulate the microporous structure of the membrane, the relationship between the microporous structure, membrane electrical charge and membrane performance and separation property. The membrane service stability will also be investigated. In order to address the above questions, we will discuss the condition of the formation of core-shell bi-component taylor cone and the deformation characteristics and movement rules of spinning jets during steady and unsteady state via high-speed photography technology; we are going to build the double diffusion kinetic model for phase separation description under the consideration of both thermodynamics and dynamics factors regarding inorganic salt and residual solvents in the process of soaking treatment ; we will also attempt to illustrate the microporous structure-performance (separation properties) relationship and the fouling control method for the hollow fiber membrane based on the nanofiltration transport model including extended Nernst-Planck equation, Gouy-Chapman theory and Donnan balance model involving ultrafine hollow fibre nanofiltration membrane structure parameters and electrical characteristics. The MATLAB software will be used to simulate and test the membrane function in the real process. In that case, experimental and theoretical findings of the development of ultrafine hollow fibre nanofiltration membrane can be provided.

全球水污染日趋恶化，膜分离已成为水资源循环应用的重要技术之一。本项目拟利用碳纳米管优良的增强效果和荷电效应，结合同轴电纺超细中空纤维膜高比表面积，开发新型碳纳米管/芳香聚酰胺超细中空纤维纳滤膜。重点围绕同轴电纺超细中空纤维纳滤膜的微孔结构构建和荷电特性、膜孔结构与应用性能间的构效关系及分离特性，纳滤膜的服役稳定性等问题进行研究。利用高速摄影技术研究“皮芯”双组分泰勒锥形成条件及射流在稳态和非稳态下的形变特征和运动规律；综合考虑浸泡过程中无机盐及残余溶剂的热力学和动力学因素，建立双扩散动力学致孔相分离模型；基于扩展的Nernst-Planck方程，Gouy-Chapman理论和Donnan平衡等结构模型，结合超细中空纤维纳滤膜结构参数、荷电特性，借助MATLAB软件模拟及测试平台上的实际运行，阐明超细中空纤维纳滤膜的构效关系、分离特性和污染与控制机理，为发展超细中空纤维纳滤膜提供理论依据。

水污染日趋恶化和能源危机已成为当今社会亟需解决的两大问题。本项目采用低温聚合法制备PMIA纺丝溶液，采用PMIA/DMAc溶液作为皮层溶液，PVP/DMF溶液作为芯层溶液，ZrCl4为致孔剂，通过同轴静电纺丝技术成功制备了皮芯结构的超细纤维，经超声浸泡去除芯层后形成超细中空纤维纳滤膜，结合水流和气流牵伸的文丘里管牵伸技术，成功制备出高取向电纺PMIA超细中空纤维膜，利用高速摄影技术研究“皮芯”双组分泰勒锥形成条件及射流在稳态和非稳态下的形变特征和运动规律，开展了PMIA超细中空纤维膜的水通量和盐分离实验测试，并研究其在不同种类和价态的电解质溶液中的动电现象，结合Nernst-Planck方程和Gouy-Chapmann方程，阐明了PMIA中空纤维纳滤膜组件的分离特性。.采用同轴静电纺丝技术成功制备了以聚偏氟乙烯(PVDF)为皮层，聚乙烯吡咯烷酮(PVP-K90)为芯层的皮芯纳微米纤维，然后经水浴超声去除PVP芯层制得直径范围为500-600nm的PVDF纳微米中空纤维。探讨了纺丝液体系的选择、溶剂体积比、内外液流速对纤维表明形貌和断面形貌的影响。结果表明：较佳的外液参数为DMF/丙酮=3:1、PVDF浓度为19%（wt）,较佳的内液参数为DMF/乙醇=8：2，PVP浓度为14%（wt）, 当外液速度为1ml/h,内液为大气压力时，此条件下纺出的纤维形貌规整，纤维直径分布均匀，壁厚均匀。.采用同轴静电纺丝技术设计并制备出一种具有“刚柔并济”(内刚外柔) 特性的皮芯结构纳米纤维膜，其中以聚酰亚胺(PI)为内芯组分、含氟PMIA为外皮组分。充分结合同轴静电纺丝技术与耐高温高强度聚合物和凝胶化隔膜等优势，所制备的PI@F-PMIA隔膜具有良好的热稳定性、较高的湿态机械强度、较强的电解液亲和力和凝胶化行为，从而能够有效地改善界面相容性、促进锂离子的高效迁移和均匀沉积，并提升隔膜对锂枝晶生长的抑制作用。采用PI@F-PMIA隔膜的锂基二次电池具有良好的离子电导率(1.30 mS cm-1)和电化学稳定窗口(~5.0 V)，其所组装的LCO/Li电池在200圈循环后仍能保持较高的放电容量(117.8 mAh g-1)和库仑效率(99.7%)。