面向染料回收利用的高选择性中空纤维膜制备及选择分离机制研究

The dye wastewater has been becoming a crucial threat for water environmental safety in China. An effective and feasible approach for the treatment of high salts, color and refractory dye wastewater is to develop a high selective hollow fiber membrane for dye recycle. Base on the design and fabrication of hydrophilic/electri-charge block copolymer and the gelation between hydrophilic block copolymer and water, this study proposes to prepare and regulate the pore structure and surface charge of high selective hollow fiber membranes via non-solvent induced gelation phase separation and polymer blend to realize selective separation and recycle of dye by the size and electric-charge of its membrane. This study focuses on materials design and membrane formation mechanism of hydrophilic and electric charge polymers, preparation and optimization of hollow fiber membrane and selective separation mechanism. It will reveal the structure and function relationship between pore structure, surface charge and separating property, ensure the high selective performance, and finally realize the controllable preparation of hollow fiber membranes. The successful implementation of this study will promote the development of a novel hollow fiber membrane materials with independent intellectual property rights, effectively solve the problem of dye wastewater treatment, and provide important technical support and novel ideas for the selective separation of dye and salts. On the other hand, it also has important academic value and broad application prospects in environmental improvement and resource utilization of wastewater.

高盐染料废水已成为威胁我国水环境安全的重要因素之一。发展高选择性中空纤维膜用于染料回收利用是解决目前高盐、高色、难降解染料废水处理的有效途径。本课题从亲水/荷电聚合物膜材料设计与制备出发，结合聚合物上亲水/荷电基团与添加剂水之间凝胶化作用，提出采用凝胶-非溶剂诱导相转化法及共混改性等手段调控中空纤维聚合物膜孔结构及表面荷电性，利用其尺寸和荷电效应协同作用实现染料与盐的高效选择性分离和回用。重点开展亲水/荷电性聚合物膜材料设计及成膜机理研究、中空膜制备与优化调控以及选择分离机制研究，揭示膜孔结构、表面荷电与分离性能间的构效关系，赋予染料与盐分离的高选择性，最终实现中空纤维膜的可控制备。本课题实施将开发出具有我国自主知识产权的高选择性中空纤维膜材料，有效解决染料废水处理所面临难题，为染料与盐选择性分离提供重要技术支撑和新思路，对改善环境、实现污水资源化利用具有重要的学术价值和广泛的应用前景。

本项目采用GNIPS法及共混改性制备三种平板疏松纳滤膜，通过调控铸膜液体系对疏松纳滤膜微观相分离，最终获得完全海绵结构、孔径大小可控、分布均一的PES/SPSf和PES/SPSf/SPES疏松纳滤平板膜。通过依据Flory-Huggins theory、Schneier theory、DSC等测试手段对聚合物体系相容性分析，设计和制备PES/SPSf中空纤维疏松纳滤膜，并探究疏松纳滤膜分离的尺寸筛分/荷电协同效应机制。主要结果如下：（1）采用GNIPS法及共混改性制备PES/SPSf、PES/SPSf/SPES、PES/QAPSf三种平板疏松纳滤膜，聚合物体系的相容性分析显示三种体系为完全相容体系。其中，PES/SPSf膜具有最优异的染料/盐的分离性能，考马斯亮蓝，直接红23和伊文思蓝截留率分别为99.2%，99.9%，98.2%和99.0%，硫酸钠的截留率＜5％。（2）采用GNIPS法制备PES/SPSf中空纤维疏松纳滤膜，其纯水渗透率63.4 LMH bar-1，断裂强度5.3 MPa。中空纤维膜组件对刚果红和硫酸钠的截留率分别为98.6%和4.1%，渗透率为26.8 LMH bar-1。（3）当刚果红浓度为1.0 g/L，仍然具有较高的截留率（94.9%）。染料溶液温度从25℃增加到80℃，PES/SPSf中空纤维疏松纳滤膜渗透率从89.3 LMH bar-1增加到145.2 LMH bar-1，刚果红截留率从99.2%减小到90.3%。当刚果红/硫酸钠溶液中硫酸钠浓度从5 g/L增加到40 g/L，渗透率从76.2 LMH bar-1减小至50.9 LMH bar-1，对硫酸钠的截留率从4.3%减小到0.4%，对刚果红截留率＞98%。（4）PES/SPSf/SPES膜对染料截留率受到尺寸筛分/荷电协同效应的影响。染料模型分子的分子量从269.3 Da增加到800 Da，协同效应贡献率从78.2%降低到50%。分子量达到800 Da时，尺寸效应和协同效应各占约50%。分子量超过800 Da，尺寸效应贡献率增加至60%，占据主导地位；此时染料截留率接近100%。本课题发表高水平学术论文20篇，发表著作或章节2部；国内外学术会议论文24篇；授权和申请中国发明专利3项；培养博士研究生5名（留学生3名）、硕士6名，共11名；相关成果获天津市技术发明二等奖1项。