支撑膜结构对聚酰胺复合膜分离性能的影响

发布时间：2018-03-28 11:18

本文选题：聚酰胺复合膜　切入点：支撑膜　出处：《天津大学》2015年硕士论文

【摘要】：界面聚合法制备的聚酰胺复合膜被广泛应用于反渗透和纳滤过程。聚酰胺复合膜由超薄皮层及多孔支撑层两部分组成,其性能可通过对皮层与支撑层的优化来提升。一般认为,皮层决定膜的透过分离性能,支撑层除了起机械支撑作用外,还对皮层的形成以及复合膜的性能有重要影响。通过调控支撑膜的表面性质、孔结构和机械强度均可进一步提升复合膜性能。本文对调控支撑膜结构和性质来优化聚酰胺复合膜性能,以及支撑膜影响复合膜皮层形成和复合膜性能的机理进行了研究。采用共混法,以聚醚砜(PES)为膜材料,以聚苯胺(PANI)为添加剂,通过浸没沉淀法制备聚醚砜/聚苯胺支撑膜,并在支撑膜上界面聚合制备聚酰胺复合纳滤膜。实验考察了聚醚砜/聚苯胺支撑膜的表面孔径、孔隙率、亲水性和通量变化,并研究了聚醚砜/聚苯胺支撑膜对复合膜皮层结构和分离性能的影响。结果显示,PANI的添加提高了支撑膜的表面孔径、孔隙率,改善了膜面亲水性,优化了支撑膜的结构和性质。支撑膜的性质影响界面聚合过程中单体的扩散及反应的进行,进而改变聚酰胺皮层的厚度及交联度。随着支撑膜中聚苯胺添加量的增加,复合纳滤膜的皮层厚度先降低后增加,皮层的交联度先增加后降低。在0.6MPa下,复合纳滤膜PA/PES/PANI-0.2的通量达到95.3 L·m-2·h-1,MgSO4的截留率达到94.9%。相比于PES支撑膜,PES/PANI-0.2支撑膜制备的纳滤膜通量提高101%,对MgSO4截留率提升了5.1%。采用制膜工艺参数优化法,调节铸膜液中聚砜浓度和非溶剂含量,通过浸没沉淀法制备海绵状结构的聚砜支撑膜,并在支撑膜上界面聚合法制备聚酰胺复合反渗透膜。分别对支撑膜及复合反渗透膜结构和性能进行表征,考察聚砜浓度对支撑膜结构和性能的影响,以及不同结构支撑膜对复合反渗透膜结构和性能的影响。结果显示,随着聚砜浓度的增加,聚砜支撑膜的表面孔径、表面孔隙率以及整体孔隙率下降,断面结构变致密,耐压性增强,纯水通量下降。在不同结构支撑膜上制备的复合反渗透膜具有不同的通量和脱盐率。综合考虑,以聚砜浓度为15%制备的海绵状支撑膜更适于作为制备复合反渗透膜的支撑层。
[Abstract]:The polyamide composite membrane prepared by interfacial polymerization is widely used in reverse osmosis and nanofiltration process. The polyamide composite membrane consists of two parts: ultrathin layer and porous support layer, and its performance can be improved by optimizing the layer and supporting layer. In addition to mechanical support, the supporting layer also has an important influence on the formation of the cortex and the properties of the composite membrane by regulating the surface properties of the supporting membrane. The pore structure and mechanical strength can further improve the performance of the composite membrane. The mechanism of the influence of the supporting membrane on the formation of the composite membrane cortex and the properties of the composite membrane was studied. Polyethersulfone / Polyaniline supported membrane was prepared by immersion precipitation method with polyethersulfone (PES) as the membrane material and Polyaniline (pan) as the additive. The polyamide composite nanofiltration membrane was prepared by interfacial polymerization on the supporting membrane. The surface pore size, porosity, hydrophilicity and flux of polyethersulfone / Polyaniline supported membrane were investigated. The effects of polyether sulfone / Polyaniline support membrane on the structure and separation properties of the composite membrane were studied. The results showed that the addition of pani increased the surface pore size, porosity and hydrophilicity of the membrane. The structure and properties of the supporting membrane were optimized. The properties of the supporting membrane affected the monomer diffusion and reaction during the interfacial polymerization, and then changed the thickness and crosslinking degree of the polyamide layer. With the increase of the amount of Polyaniline in the supporting film, The cortical thickness of composite nanofiltration membrane first decreased and then increased, and the degree of cortical crosslinking increased first and then decreased. The flux of composite nanofiltration membrane PA/PES/PANI-0.2 reached 95.3 L m -2 h-1 h -1 MgSO 4 retention rate of 94.90.Compared with that of PES support membrane PES / PANI-0.2 support membrane, the flux of nanofiltration membrane increased 101%, and the rejection rate of MgSO4 increased 5.1%. The polysulfone supporting membrane with spongy structure was prepared by immersion precipitation method by adjusting the concentration of polysulfone and the content of non-solvent in casting solution. Polyamide composite reverse osmosis membrane was prepared by interfacial polymerization on the supporting membrane. The structure and properties of the supporting membrane and the composite reverse osmosis membrane were characterized, and the effects of the concentration of polysulfone on the structure and properties of the supporting membrane were investigated. The results show that with the increase of the concentration of polysulfone, the surface pore size, surface porosity and overall porosity of the membrane decrease, and the cross section structure becomes denser. The composite reverse osmosis membrane prepared on the membrane with different structure has different flux and desalination rate. The spongy supporting membrane with 15% polysulfone concentration is more suitable for preparing composite reverse osmosis membrane.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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