氧化石墨烯—聚丙烯腈基纳滤膜的制备及性能研究

发布时间：2018-04-17 07:47

本文选题：纳滤膜 + 聚丙烯腈　；参考：《东华大学》2017年硕士论文

【摘要】：膜分离技术具有分离高效、浓缩、提纯和净化等优点。近年来,随着人们对水资源需求和用水标准的日益增长,污水处理的压力日益增加,纳滤膜的研究得到了极大促进。纳滤膜的分离性能介于超滤膜和反渗透膜之间,主要用于分离分子量在200-2000之间的小分子物质,被广泛用于硬水软化、印染废水处理、食品工业和制药工业等领域。传统制备纳滤膜所采用的非溶剂致相分离法和复合法等易导致膜强度低、结构可控性差、复合层易剥离等缺点,进而造成纳滤膜结构和性能稳定性差等问题。聚丙烯腈的玻璃态转变温度较高,具有良好的热稳定性、耐溶剂性、化学稳定性和较好的亲水性,所以常用来制备反渗透的基膜,超滤膜等,但聚丙烯腈结构单元中有强极性的氰基,使分子链旋转困难,造成聚丙烯腈膜材料的机械强度和韧性差,因而限制了其广泛应用。无机/高分子复合膜兼具聚合物优异的加工性能和无机填料的独特性能,是今后分离膜的发展方向。作为一种新型优质聚合物改性材料,氧化石墨烯具有良好的亲水性、较高的比表面能以及机械性能。本文采用热致相分离法和小分子层层自组装法制备了结构稳定、力学性能和分离效果良好的抗污染纳滤膜。首先采用热致相分离法制备氧化石墨烯/聚丙烯腈复合膜,所制备的复合膜表现出优异的力学强度、较高的渗透性能、高染料截留率、低盐截留率以及良好的抗污性能,适用于印染废水的处理和染料的纯化处理。研究发现聚丙烯腈膜的膜孔结构、相分离温度、孔隙率、渗透和机械性能等受添加剂种类、聚合物浓度、冷却浴等因素的影响,结果表明采用与聚丙烯腈相容性较差,极性分数和分子量较小的甘油作为添加剂所制备的膜性能较好。增加聚合物浓度使得膜结构变致密,体系的相分离温度升高,膜的孔隙率和纯水通量下降,拉伸强度和染料的截留率增大。降低冷却速率使得分离膜结构变疏松,孔隙率增大且水通量上升。采用溶剂交换法将制备好的氧化石墨烯均匀分散在膜中制备得到氧化石墨烯/聚丙烯腈共混膜,发现氧化石墨烯的加入使得聚合物晶粒尺寸增大,当氧化石墨烯的添加量0.2wt%,共混膜的水通量比原膜提高了83%,具有高染料截留和低盐截留性能。由于氧化石墨烯的亲水性和增强效果,分离膜的通量恢复率和拉伸强度分别提高到84%和12.46mpa。采用胺化改性的氧化石墨烯/聚丙烯腈共混膜作为基膜,再用界面聚合和小分子层层自组装法制备复合纳滤膜,胺化改性膜表面的胺基能提高基膜与活性层的结合力。与界面聚合法相比,采用小分子层层自组装法制备的纳滤膜结构更稳定,膜的表面电荷可调控;通过改变反应单体种类发现采用刚性结构的间苯二胺制备的膜分离性能比柔性结构的二乙烯三胺更优,随着自组装层数增加,分离膜水通量下降而截留率增加;通过在自组装过程中引入氧化石墨烯能够提高纳滤膜的截留性能,氧化石墨烯溶液的最佳浓度为1mg/ml,调节单体浓度、反应时间和热处理温度探索复合纳滤膜的最佳制备条件,测试发现复合膜性能发现小分子层层自组装复合膜具有较高的无机盐截留率和抗污性能,对硫酸钠的截留率为74.7%,膜表面负载的氧化石墨烯优异的亲水性使分离膜的通量恢复率达到91.3%。
[Abstract]:Membrane separation technology has the advantages of efficient separation, concentration, purification and purification. In recent years, with the increasing demand of water resources and water standards, the pressure of the sewage treatment is increasing, the research of nanofiltration membrane has been greatly promoted. Between the separation performance of nanofiltration membrane between ultrafiltration and reverse osmosis membrane, mainly used for separation the molecular weight of small molecules between the 200-2000, is widely used for water softening, printing and dyeing wastewater treatment, food and pharmaceutical industry and other fields. The traditional non solvent preparation of nanofiltration membrane by induced phase separation method and composite method is easy to cause the membrane structure of low strength, poor controllability, composite layer easy peeling defects then the problems caused by nanofiltration membrane structure and performance stability. The glass transition temperature of polyacrylonitrile high, has good thermal stability, solvent resistance, chemical stability and good hydrophilic, so often Used for preparation of reverse osmosis membrane, ultrafiltration membrane, but the structure of polyacrylonitrile unit has strong polar cyano, the molecular chain rotation caused by the material difficulties, polyacrylonitrile membrane mechanical strength and toughness is poor, which limits its wide application. With the unique properties of polymers with excellent mechanical properties and inorganic fillers inorganic / polymer composite membrane, membrane separation is the future direction of development. As a new high polymer modified materials, graphene oxide has good hydrophilicity, high surface energy and mechanical properties. This method and small molecular self-assembly were prepared by thermally induced phase separation structure stability, mechanical properties and good separation effect the anti pollution nanofiltration membrane. Firstly using heat to prepare graphene oxide / PAN composite membrane induced phase separation, the prepared composite films exhibit excellent mechanical strength, high permeability, high The dye retention rate, low salt rejection and anti fouling performance good, purification and treatment of dyes for dyeing wastewater. The study found that the porous structure of polyacrylonitrile membrane, phase separation temperature, porosity, permeability and mechanical properties by additives, polymer concentration, cooling bath and other factors, the results show that the use of poor compatibility with polyacrylonitrile, polar fraction and low molecular weight glycerol as additive membranes were prepared. The performance is better with increasing the polymer concentration makes the membrane structure compact, phase separation temperature system, decrease the porosity and the pure water flux, retention rate of tensile strength increases and dyes. Lower cooling rate makes the separation membrane the loose structure, porosity and water flux increase. The solvent exchange method for graphene oxide prepared uniformly prepared graphene oxide / Polypropylene Membranes Nitrile blend film, found that adding graphene oxide makes the polymer grain size increases, when the graphene oxide 0.2wt% was added, the water flux was 83% higher than the original film, with high dye retention and low salt rejection performance. Due to the hydrophilicity of graphene oxide and enhance the effect of graphene oxide / separation the membrane flux recovery rate and tensile strength were increased to 84% and 12.46mpa. by amination of modified polyacrylonitrile blend membrane as a basement membrane, and interfacial polymerization and small molecular self-assembly preparation of composite nanofiltration membrane, amino amine modified membrane surface can increase the adhesion between the basement membrane and the active layer. Compared with the method of interfacial polymerization using small molecule layer self nanofiltration membrane structure assembly prepared more stable. The surface charge of the membrane can be controlled by changing the reaction; the monomer species found by membrane separation performance between the two benzene amine preparation rigid structure than The flexible structure two three ethylene amine is better, with self assembled layers increased, membrane water flux decreased and the retention rate increased; through the self-assembly process into graphene oxide can improve the retention performance of nanofiltration membrane, the optimal concentration of graphene oxide solution is 1mg/ml, adjusting the monomer concentration, reaction time and preparation conditions the heat treatment temperature on composite nanofiltration membrane was optimized, the test found that the properties of the composite film found inorganic small molecular self-assembly composite membrane has high retention rate and anti fouling performance of sodium sulfate removal rate is 74.7% and the surface negative hydrophilic graphene oxide carrier excellent separating membrane flux recovery rate reached 91.3%.

【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

【参考文献】