基于界面聚合与热致相分离法的压力延迟渗透膜的制备及盐差发电性能研究

Pressure retarded osmosis (PRO) is the most promising technology to capture salinity-gradient energy. Its main challenge is to develop novel PRO membranes with stable structure, high strength, adequate flow and solute rejection. In order to breakthrough current limitations of preparation method for support layer, structure stability and membrane strength, we suggest that polyamide/cellulose triacetate/stainless steel mesh composite PRO membranes with excellent resistance to pressure could be fabricated through a new procedure based on interfacial polymerization and thermally induced phase separation (TIPS) method. Various kinds of pores with tubular, polyhedral, sponge or honey-comb like structures could be fabricated in support layers by modulating the thermodynamic and kinetic parameters of TIPS process. Corresponding TIPS mechanism will be elucidated to understand the pore formation. On the other hand, much attention will be focused on the affecting parameters of interfacial polymerization, especially the influence of pore structures of support layers on the surface morphology and permeability of polyamide active layers. Based on these data, we try to significantly improve the stable composite of active layer on the support layer, and finally obtain robust PRO membranes. After that, a series of PRO membranes with different pore structures on the support layers will be detailedly investigated to gain their basic parameters, such as mechanical strength, mass transfer properties and structure parameters. These results will be used to build the relationship between the pore structures of support layers and the performance of PRO membranes, including the salinity-gradient energy generation, resistance to pressure, and permeability. We hope this knowledge will contribute to the development of novel PRO membranes.

压力延迟渗透技术是目前最具潜力的盐差发电方式之一，其核心和关键是设计与制备结构稳定、耐压性强、水通量大、截盐率高的压力延迟渗透膜。本项目旨在突破现有技术在支撑膜的制备方法、结构稳定性和机械强度等方面的局限，组合界面聚合法和热致相分离法的优势，建立新型耐压性的聚酰胺/三醋酸纤维素/不锈钢网复合压力延迟渗透膜的制备新方法；系统调控热致相分离过程的热力学和动力学参数，实现柱状、多面块状、海绵状、蜂窝状等多种支撑层孔结构的构建，阐明其形成与调控机制；详细研究界面聚合各参数，重点讨论支撑层孔结构对聚酰胺超薄活性层的表面结构和渗透性能的影响，优化制备方法以获得活性层与支撑层复合稳定的压力延迟渗透膜；深入探讨一系列支撑层孔结构不同的压力延迟渗透膜的机械强度、传质特性、结构参数，建立支撑层孔结构与压力延迟渗透膜的盐差发电性能、耐压性、水渗透性之间的内在关联，为新型压力延迟渗透膜的设计提供新思路和理论指导。

压力延迟渗透技术是目前最具潜力的盐差发电方式之一，其核心和关键是设计与制备结构稳定、耐压性强、水通量大、截盐率高的压力延迟渗透膜。本项目旨在利用热致相分离法和三醋酸纤维素的优势突破现有技术在支撑膜的制备方法、结构稳定性和机械强度等方面的局限，再结合界面聚合物法构建新型薄膜复合渗透膜。经过三年的系统探索，我们取得的主要亮点包括：1）建立了亲水性三醋酸纤维素多孔膜的热致相分离制备新方法，拓展和丰富了三醋酸纤维素膜的制备方法和应用范围。成功地筛选出以二甲基砜为稀释剂、聚乙二醇400为添加剂的三元成膜体系。该体系动力学上发生固固相分离，可用于构建胞腔状、花边状、片状或椭圆形等孔结构。通过调控聚合物浓度、稀释剂配比和冷却方式等因素可调控三醋酸纤维素多孔膜的孔结构、孔隙率、水通量和机械性能；2）在三醋酸纤维素多孔膜表面实现了界面聚合，完善了界面聚合法制备薄膜复合渗透膜的工艺。通过调控膜厚度、稀释剂配比和聚合物浓度得到不同结构和性质的三醋酸纤维素多孔膜，并以此为基础探究和总结了多孔支撑层结构和性质对薄膜复合渗透膜的结构和性能之间的影响规律。研究表明，利用较低厚度（~50 m）的模具、低聚合物浓度（10 wt%）、合适的稀释剂比例（聚乙烯醇400含量）制得的三醋酸纤维素多孔膜为支撑层，可获得具有较高水渗透通量、截盐率、选择性和较低结构参数的薄膜复合渗透膜；3）通过聚多巴胺/聚乙烯亚胺共沉积改性三醋酸纤维素多孔膜，优化共沉积条件，可极大地提高薄膜复合渗透膜的选择性，拓宽了薄膜复合渗透膜的改性新方法。相关研究成果包括：发表SCI收录论文6篇，其中影响因子3.0以上论文2篇，投稿或即将投稿论文3篇；申请国家发明专利5项，其中授权1项；参加国际学术会议1人次；培养硕士研究生1名。