石墨烯量子点纳滤膜孔结构调控与分离性能强化

Achieving the efficient mono/bivalent ion separation through the construction and manipulation of pore structures of nanofiltration membrane is a hot issue in membrane field. In this project, the graphene quantum dots will be incorporate into polyamide nanofiltration membrane separation layers by interfacial polymerization technology, and the nanofiltration membranes with robust structure, pricise mono/bivalent ion sieving ability and high permeation flux will be fabricated using the appropriate size, surface functional groups and charge of graphene quantum dots. The key scientific problem is: how to realize pore structure building and coordination optimization for the graphene quantum dots of nanofiltration membranes. The chemical method, physical method, film forming dynamics and thermodynamics method, are used to regulate the forming process of the network pores/aggregation pores in the graphene quantum dots of nanofiltration membranes. The polyamide with relatively flexible network pores is proposed to improve the stability of the rigid aggregation pores with graphene quantum dots. Coordination optimization for the size sieve and electrostatic repulsion separation mechanism is carried out. The relationship between the network pores/aggregation pores structure and mono/bivalent ions separation ability will be exploited at the molecular level. The efficent process intensification will be realized. Hopefully, the implementation of this project will present new materials and methods for the rational design and structure manipulation of nanofiltration membrane preparation, and meanwhile to promote the application of nanofiltration technology in wastewater deep treatment and reclamation.

通过纳滤膜孔结构构建与调控，实现一/二价盐离子的高效分离是膜领域的研究热点之一。本项目拟采用界面聚合技术，在聚酰胺纳滤膜分离层引入石墨烯量子点，利用石墨烯量子点的单分子层、小尺寸、高表面活性、荷电性等特征，制备结构稳定、具有一/二价离子精密筛分能力和高通量的石墨烯量子点纳滤膜。拟解决的关键科学问题是：如何实现石墨烯量子点纳滤膜孔结构的可控构建和协调优化。重点研究化学方法、物理方法、成膜动力学和热力学方法，调控石墨烯量子点纳滤膜中网络孔与堆积孔的形成过程，以相对柔性的聚酰胺网络孔来稳定刚性的石墨烯量子点堆积孔结构。协调优化网络孔和堆积孔的尺寸筛分和静电排斥分离机制。在分子水平上揭示石墨烯量子点纳滤膜网络孔和堆积孔的微观结构与传质机制、分离性能之间的构效关系，以实现一/二价盐离子分离过程的高效强化，期望为纳滤膜的设计制备与结构调控提供新材料与新方法，促进纳滤在废水资源化过程中的应用。

柠檬酸热解方法制备的石墨烯量子点，粒径小于5nm,表面有丰富的活性基团，水溶液中易分散。石墨烯量子点表面的羟基、环氧、羧基等基团，可以参与界面聚合，是构筑和调控纳滤膜和反渗透膜的极佳材料。石墨烯量子点可以是致孔剂、交联剂、表面改性剂。.界面聚合过程中，石墨烯量子点与均苯三甲酰氯，通过酯键形成交联结构。酯键提高了纳滤膜的化学稳定性，可以制备高通量、耐酸碱、耐氧化的纳滤膜。发现石墨烯量子点与聚酰胺之间存在界面孔道，构建了新的水通道，提高了纳滤膜的水渗透通量。.石墨烯量子点可以调控界面聚合过程中水相单体的扩散。在无支撑界面聚合过程中，石墨烯量子点减缓哌嗪扩散，水相单体哌嗪和油相单体均苯三甲酰氯的相对可控的界面聚合反应，形成更薄更均匀的聚酰胺分离层，极大提高了纳滤膜的渗透通量。.以石墨烯量子点纳滤膜为组装材料，层层组装制备复合纳滤膜，残留的氨基和酰氯基团发生化学反应，原位形成聚酰胺中间层。聚酰胺中间层为网络孔结构，在保持纳滤膜高通量的前提下，获得了超高的硫酸钠截留率和氯离子硫酸根离子分离因子。.石墨烯量子点纳滤膜孔结构调控与分离性能强化的研究，取得一些原创性研究成果。石墨烯量子点增强的高性能纳滤膜（Na2SO4截留率99.6%，渗透通量32.1 Lm-2h-1bar-1，Cl-/SO42-的选择性达到205.8），突破Trade-off效应; 石墨烯量子点直接参与界面聚合制备纳滤膜（通量244.7  Lm-2h-1bar-1，染料刚果红截留率98.8%），石墨烯量子点制备正电荷膜纳滤膜，石墨烯量子点制备抗氧化纳滤膜，以及石墨烯量子点制备抗污染膜。层层组装的石墨烯量子点复合纳滤膜，获得硫酸钠截留率为99.9%，氯离子硫酸根离子分离因子为637.0的超高的分离性能。.纳滤膜分离广泛用于化工废水零排放、工业废水处理、海水淡化等领域，高性能纳滤膜可以节约成本、降低能耗、减少投资。本研究项目促进了聚酰胺纳滤膜的发展，应用前景广阔。