低温等离子体联合界面聚合制备反渗透复合膜方法及膜分离性能研究

The separation performance of reverse osmosis composite membrane prepared by interfacial polymerization was not only affected by the surface morphology, chemical composition, structure and the charging characteristics of the ultrathin functional layer, but also was strongly dependent on the synergy among the support layer, the support layer / ultrathin functional layer interface and the ultrathin functional layer. This study uses plasma to improve support film etching, crosslinking effect, hydrophilicity and bonding performance, to increase the membrane flux, extend membrane selection range, and enhance the membrane interception efficiency and chlorine resistance..Firstly, the membranes were modified by different processing methods and control parameters of low temperature plasma, then reverse osmosis composite membrane prepared by interfacial polymerization. Secondly, the surface performance of prepared film was tested by ATR-FTIR, XPS, SEM, TEM, AFM and other detection means. The microscopic characteristics of composite membrane were analyzed by these detection means. Then the macro performance of different composite membrane was obtained through separation test. Finally, the relationship between the microscopic properties and macroscopic properties of composite membrane were found by data analysis. Based on the understanding of the influence of plasma treatment on interfacial polymerization and their interaction, explore the change law of membrane separation performance under this influence, guide the prepared method of high performance composite reverse osmosis membrane by low-temperature plasma and interface polymerization.

界面聚合制备的反渗透复合膜分离性能除受超薄功能层表面形态形貌，化学组成、结构及其荷电特性的影响外，还强烈依赖于支撑层、支撑层/超薄功能层界面及超薄功能层之间的协同作用。本研究利用等离子体对支撑基膜的刻蚀、交联效应、亲水化和粘结性能改善作用，以增大膜通量，扩展基膜选择范围，提升膜的截留效率和耐氯性能。.研究首先用不同低温等离子体的处理方法和控制参数对基膜进行改性，再利用界面聚合制备反渗透复合膜。其次，对制备得到的膜采用ATR-FTIR、XPS、SEM、TEM、AFM等检测手段进行表面性能测试，分析复合膜的微观特性；然后通过分离试验比较不同复合膜的宏观性能表现；最后采用数据分析方法研究复合膜微观特性与宏观性能之间的联系。在此基础上认识和理解等离子体处理方法对界面聚合的影响及相互作用关系，探索膜分离性能在该作用关系下的变化规律，以指导低温等离子体与界面聚合联用制备高性能反渗透复合膜的方法。

用空气、氩气和氮气低温等离子体对聚砜（PS）和聚偏氟乙烯（PVDF）基膜进行照射和液相引发接枝丙烯酸（AA）改性处理。以间苯二胺（MPD）和均苯三甲酰氯（TMC）进行界面聚合在改性基膜上制备反渗透复合膜。探究等离子体气体氛围、功率、放电电流和放电时长对基膜表面性质的作用及对反渗透复合膜分离性能的影响。结果表明，PS基膜改性后制备的复合膜功能皮层与基膜粘接性得到很好改善，最大提高58.9%；膜通量和盐截留率分别可有10%和1～3%的小幅提升；PVDF基膜改性后制备的复合膜盐截留率提升明显，最高可达86.32%，较未改性基膜提高32.96%，同时粘接性增加35%以上，为疏水性基膜的界面聚合反渗透膜制备提供方法参考。探究改性对基膜表面主要性质的定性和定量作用影响，认为等离子改性可对基膜表面孔隙、粗糙度、润湿性及表面力产生作用与调控，适合的改性方法有利于改善界面聚合的基膜表面条件。改性的PS基膜接触角及表面张力与制备的复合膜截留率及通量呈现较强的相关性，相关系数分别为-0.797、-0.743，0.779、0.769；通过实验回归方程反演分析获得等离子基膜改性关键参数控制范围。选择烯丙胺、3-丁烯腈、丙烯酸、甲基丙烯酸甲酯、丙烯酸羟乙酯、N-乙烯基吡咯烷酮、4-乙烯基吡啶7种单体用射频和介质阻挡放电等离子体放电直接聚合制备反渗透复合膜，考察了放电时长、单体质量流率、放电功率等参数对复合膜截留率及通量性能作用与影响，初步明确单体流率、放电反应时长和溶胀时长是聚合制备的显著关键因素并获得取值范围。结果表明，各单体制备复合膜都有脱盐性，但截留率不高10～50%，介质阻挡放电较射频等离子体聚合膜性能更好，其放电的均匀性改善和等离子体聚合机理明确是复合膜性能提高的关键问题。研究成果为高性能反渗透复合膜制备、扩展单体选择范围及新型制备方法提供科学支持和技术借鉴。