基于纳米材料共混超滤膜亲水改性与特性研究

发布时间：2018-02-03 18:03

本文关键词： 聚偏氟乙烯超滤膜共混纳米氧化铝纳米二氧化钛氧化石墨烯　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：高分子聚合物聚偏氟乙烯(PVDF)由于其良好的热稳定性、机械稳定性能和化学稳定性等特点而得到了广泛的应用,但其固有的表面能低和表面强疏水性较易与截留的污染物质相互作用,导致膜污染的快速发生和膜通量持续衰减,膜使用寿命降低,增加PVDF膜应用过程中的成本。控制膜污染的有效途径之一是对膜材料进行表面亲水改性,本文分别采用纳米氧化铝(Al_2O_3)、纳米二氧化钛(TiO_2)和氧化石墨烯(GO)三种纳米材料,通过共混的方法对PVDF超滤膜进行表面亲水改性,制备抗污染性强和亲水性高的改性超滤膜,为缓解超滤膜的膜污染提供技术支持。采用共混法制备PVDF/TiO_2和PDVF/Al_2O_3超滤膜,并对改性前后的性能特征和表面形貌进行系统比较,研究结果表明:共混纳米无机盐后的改性超滤膜表面亲水性显著提高、纯水通量增大,且未影响对有机物的截留效率。采用扫描电子显微镜(SEM)对超滤膜的形貌进行分析,结果表明,改性膜具有与未改性膜相似的致密结构和指状孔结构,纳米TiO_2和Al_2O_3无机盐颗粒较均匀的分布在膜表面,共混添加纳米颗粒未影响超滤膜的形貌结构。通过共混法制备PVDF/GO超滤膜,通过SEM表征分析显示,改性超滤膜表面微孔数量显著增多,断面中指状孔结构增大,超滤膜的水通量显著提升。共混GO后的超滤膜亲水性提高,但是共混氧化石墨烯的超滤膜对牛血清白蛋白、酪氨酸、色氨酸类蛋白质、可溶性生物代谢产物、富里酸和腐殖酸类物质的截留效果显著下降。优选出综合性能好的超滤膜研究改性亲水超滤膜的抗污染性能和抑菌抗生物型污染能力,在过滤腐殖酸、蛋白质和多糖等不同表面特性大分子有机物时,改性超滤膜的通量衰减速度及其不可逆污染阻力均显著低于未改性超滤膜,表明亲水纳米材料的共混显著提高膜的抗污染性能。将改性超滤膜用于膜生物反应器并处理实际污水,其跨膜压差(TMP)增长速度较未改性膜显著减缓,且膜生物反应器对COD、NH_4~+-N去除率可分别维持在95%、96%。同时,在抑菌抗生物型污染实验过程中也表明改性超滤膜表面的细菌数量和种群多样性均显著降低,表明其突出的抗污染能力。
[Abstract]:Polyvinylidene fluoride polyvinylidene fluoride (PVDF) polymer has been widely used because of its good thermal stability, mechanical stability and chemical stability. However, its inherent low surface energy and strong hydrophobicity easily interact with retained pollutants, which leads to the rapid occurrence of membrane fouling, the continuous decline of membrane flux, and the decrease of membrane service life. One of the effective ways to control membrane fouling is surface hydrophilic modification of membrane material. The surface hydrophilic modification of PVDF ultrafiltration membrane was carried out by blending three kinds of nanomaterials such as TiO-2) and graphene oxide (GOO). PVDF/TiO_2 and PDVF/Al_2O_3 ultrafiltration membranes were prepared by blending method to provide technical support for reducing membrane fouling. The results showed that the surface hydrophilicity and pure water flux of the modified ultrafiltration membrane after blending nano-inorganic salt were improved significantly. Scanning electron microscopy (SEM) was used to analyze the morphology of ultrafiltration membrane. The results showed that the modified membrane had dense structure and finger-like pore structure similar to that of unmodified membrane. Nano TiO_2 and Al_2O_3 inorganic salt particles distributed evenly on the surface of the membrane. The morphology and structure of the ultrafiltration membrane were not affected by adding nano-particles into the blend. PVDF/GO ultrafiltration membrane was prepared by blending method. SEM analysis showed that the number of micropores on the surface of modified UF membrane was significantly increased, the phallic pore structure in the section was increased, the water flux of UF membrane was significantly increased, and the hydrophilicity of UF membrane was increased after blending with go. However, the ultrafiltration membrane of mixed graphene oxide on bovine serum albumin, tyrosine, tryptophan proteins, soluble biological metabolites. The retention effect of fulvic acid and humic acid was significantly decreased. The excellent ultrafiltration membrane with good comprehensive performance was selected to study the antifouling performance and bacteriostatic anti-biological pollution ability of the modified hydrophilic ultrafiltration membrane in the filtration of humic acid. The flux attenuation rate and irreversible fouling resistance of modified ultrafiltration membrane were significantly lower than that of unmodified ultrafiltration membrane when macromolecular organic compounds with different surface characteristics such as protein and polysaccharide. The results showed that the blend of hydrophilic nanomaterials significantly improved the anti-fouling performance of the membrane. The growth rate of the transmembrane pressure difference (TMP) was significantly slower than that of the unmodified membrane when the modified ultrafiltration membrane was used in the membrane bioreactor and treated with actual sewage. The removal rate of COD _ 4 ~ -N in membrane bioreactor can be maintained at 95 ~ 96% respectively. It was also shown that the number of bacteria and the diversity of population on the surface of the modified ultrafiltration membrane were significantly decreased during the experiment of bacteriostatic and biological pollution, which indicated its outstanding anti-fouling ability.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TQ051.893

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