LBL自组装高水通量氧化石墨烯框架复合膜及资源化处理离子型稀土工业废水的机理研究

Ionic-type rare earth (RE) ore is the specific strategic resources in China, while it produces a large amount of wastewater during smelting processes. However, there are still containing RE ions in the exhausted water after treated with traditional separation technology. Therefore, it is of great significance to develop new technology for RE wastewater treatment and RE ions resource recycling for comprehensive utilization. In this project, the relationship among the membrane preparation conditions, membrane surface microstructure and their separation performance will be investigated in details. The high-flux water-permeable graphene oxide framework (GOF) composite membranes with high RE ions rejection and stability are prepared by the lay-by-lay (LBL) self-assembly technology with precise tunable d-spacing for GOF materials and membrane surface microstructure, which are regulated by covalent cross-linkers and surface modification methods. The influence of membrane preparation conditions and different experimental conditions such as temperature, pressure, pH, RE ion concentration, salt concentration, ionic strength, membrane operation modes, etc. on the membrane separation performance or enrichment of RE ions in wastewater are discussed. Moreover, with the aid of mathematical simulation combined with the experimental data and effective characterization methods, the interaction between RE ions and GOF membranes interface, and mass transfer mechanism of water and RE ions through the membrane layers are studied in high-salt RE wastewater systems. It will be to improve the separation performance, stability and preparation of repeatability for the GOF membranes. It will be to provide scientific support for the development of new membrane materials for application in the RE wastewater treatment, recycling resource and comprehensive utilization in China.

离子型稀土为我国特有的战略性资源，其冶炼过程会产生大量废水，经现有技术处理后排放水中仍含有稀土离子。因此开展稀土废水处理新技术及稀土资源化回收的研究具有十分重要意义。在深入研究膜的“制备条件-表面微结构-分离性能”三者关系的基础上，通过共价交联剂、膜表面修饰手段对膜的d-spacing和微结构的精准调控，利用LBL自组装出高水通量的氧化石墨烯框架（GOF）复合膜。系统考察GOF膜的制备条件、膜操作条件（温度、压力、pH、稀土离子浓度、盐浓度、膜操作方式等）对GOF膜分离/浓缩富集稀土离子性能的影响；结合有效的表征手段和传质数学模型，研究稀土离子在复合膜表界面上的作用机制；探究高盐稀土废水处理过程中水和稀土离子在膜层的传质机理，提高膜的分离性能、稳定性能和制备重复性，为我国新型膜分离材料在稀土工业废水的绿色高效处理及资源化综合利用中提供重要科学依据。

离子型稀土为我国特有的战略性资源，其冶炼过程会产生大量废水，现有技术处理后排放水中仍含有稀土离子。因此开展稀土废水处理新技术及稀土资源化回收的研究具有十分重要意义。基于对膜的d-spacing和微结构的精准调控，分别以碳纳米管、天然凹土纳米棒、乙二胺四乙酸、尿素、聚酰胺基胺、含醚氧基二胺和氨基酸小分子等为交联剂，通过共价交联反应优化制备出了具有三维氧化石墨烯框架结构的高性能GOF复合膜。GOF复合膜片层间形成的共价键，有利于抑制纯GO溶胀从而有利于调控膜的d-spacing、稳定性和膜表面微观结构（亲水性）从而大大提高膜的分离性能。与纯GO膜相比，GOF膜的渗透通量至少提高5倍以上，而截留率近乎100%且具有优异的长时间热稳定性和耐酸碱稳定性。系统考察了GOF膜的制备条件、膜操作条件（温度、压力、pH、稀土离子浓度、盐浓度、膜操作方式等）对GOF膜分离/浓缩富集稀土离子性能的影响，建立了以盐水溶液中的水真实饱和蒸气压P^sat，膜渗透率P与盐种类N、盐浓度C、进料温度T、渗透率活化能Ep之间的关联函数（P^sat=f(N,C,T)，P =f (N,C,T,Ep)）为基础的数学模型，定量揭示出高盐稀土工业废水的GOF复合膜脱盐过程的演化规律与作用机制。通过多种表征手段，建立了GOF膜的“制备条件—微观结构—分离性能”之间的关联，测定膜表面的亲疏水性和干态/湿态d-spacing（水通道大小）等参数，构建了水分子在GOF膜层传递输运行为的动态数学模型和定量描述方法，初步揭示出GOF膜在高盐稀土废水处理过程中水和稀土离子在膜层的传质机理。高性能GOF复合膜将在海水淡化（脱盐）、稀土废水/重金属废水（高盐废水）处理等领域中具有潜在的应用前景。