基于两性离子修饰纳滤膜的制备与性能研究

发布时间：2018-05-04 09:53

本文选题：纳滤膜 + 抗污染性能　；参考：《浙江工业大学》2017年硕士论文

【摘要】：纳滤膜因在分离过程中有操作压力低、选择分离性好等优势而被广泛使用,但因其在分离过程中易受蛋白污染而导致其通量下降,截留率降低,使用寿命减短,这大大限制了纳滤膜的使用范围,因此纳滤膜的污染问题亟待解决。两性离子可以通过氢键和库伦力在其周围形成牢固的水层,从而有效地抑制蛋白质吸附,这一特性使其成为制备超低污染膜的有效改性材料之一。本文主要通过两步法将叔铵基和磺酸基接枝到聚哌嗪酰胺纳滤膜表面,重点研究此改性方法中两性离子纳滤膜的抗污染性能及其影响因素。在偶氮二异丁腈(AIBN)的引发作用下,将甲基丙烯酸二甲氨基乙酯(DMAEMA)接枝到聚哌嗪酰胺纳滤膜的表面,随后用1,3-丙磺酸内脂进行季铵化处理,在膜的表面形成磺酸型两性离子。采用FTIR、XPS、AFM、SEM等进行分析,结果表明两性离子已成功接枝到膜表面,且膜表面的粗糙度和亲水性较改性前均有所增加,这使膜表面与水接触面积增大,从而起到提高膜通量的作用。同时膜改性前后内部和表面结构均没有发生明显改变,这说明改性接枝反应并没有对膜的结构造成破坏。此外,采用牛血清蛋白为模型蛋白对改性后的膜进行动态和静态蛋白吸附测试,结果显示随着两性离子接枝密度的增加,膜对蛋白质的吸附量从原始膜120μg/cm2显著下降到1.86μg/cm2,表明经改性后的膜表面对于抑制蛋白质吸附的能力已大大提高。膜的动态过滤实验也表明经改性的纳滤膜,其通量恢复率得到明显提高。当1,3-丙磺酸内脂接枝密度为311μg/cm2时,膜的水通量从68.3L/m2·h提高到了88 L/m2·h,同时经蛋白污染后其通量降低率为37.2%。而原始纳滤膜的通量降低率为57.6%,表明改性后的纳滤膜受到污染后,其通量降低率小于改性前。膜的通量恢复率可达到92.00%,而空白膜的通量恢复率仅为67.20%,这均说明膜的抗生物污染性能已得到了明显提高。最后采用阻力叠加模型分析改性后的纳滤膜在蛋白分离过程中的阻力及阻力分布情况。结果表明:经改性后的纳滤膜在蛋白分离过程中的阻力主要来自膜本身的阻力(Rm),其约占总阻力的75.38%,浓差极化阻力及边界层阻力依次为15.08%、9.53%,低于原始纳滤膜的27.52%、21.96%。这表明经改性后的膜较空白膜的抗生物污染性能已有明显提高,在蛋白分离及生物医药领域有较好的应用前景。
[Abstract]:Nanofiltration membrane is widely used because of its advantages of low operating pressure and good selectivity in the separation process. However, the flux, retention rate and service life of nanofiltration membrane are decreased due to its easy contamination by protein in the separation process. This greatly limits the scope of application of nanofiltration membrane, so the pollution of nanofiltration membrane needs to be solved. Amphoteric ions can form a solid water layer around them by hydrogen bonding and Coulomb force, which effectively inhibits the adsorption of proteins, which makes them one of the effective modified materials for the preparation of ultralow fouling films. In this paper, the tertiary ammonium group and sulfonic acid group were grafted onto the surface of polypiperazinamide nanofiltration membrane by two-step method. The anti-fouling performance of amphoteric nanofiltration membrane and its influencing factors were studied. Under the initiation of azodiisobutyronitrile (AIBN), dimethylaminoethyl methacrylate (DMAEMA) was grafted onto the surface of poly (piperazinamide) nanofiltration membrane. The results show that the amphoteric ions have been grafted onto the membrane surface successfully, and the roughness and hydrophilicity of the membrane surface have been increased compared with those before modification, which increases the water contact area between the membrane surface and the water, thus enhancing the membrane flux. At the same time, there was no obvious change in the internal and surface structure before and after the membrane modification, which indicated that the modified graft reaction did not damage the membrane structure. In addition, bovine serum protein was used as model protein to test the dynamic and static protein adsorption of the modified membrane. The results showed that the grafting density of amphoteric ions increased with the increase of amphoteric ion grafting density. The amount of protein adsorbed by the modified membrane decreased significantly from 120 渭 g/cm2 to 1.86 渭 g / cm ~ (2), which indicated that the ability of the modified membrane surface to inhibit the adsorption of protein was greatly improved. The dynamic filtration experiments also showed that the flux recovery rate of the modified nanofiltration membrane was improved obviously. The water flux of the membrane increased from 68.3L/m2 h to 88 L/m2 h when the grafting density was 311 渭 g/cm2, and the flux decreased by 37.2% after protein contamination. The flux reduction rate of the original nanofiltration membrane was 57.6, which indicated that the flux reduction rate of the modified nanofiltration membrane was lower than that of the modified membrane after fouling. The flux recovery rate of the membrane was 92.00 and that of the blank membrane was only 67.20, which indicated that the anti-fouling performance of the membrane had been improved obviously. Finally, the resistance and resistance distribution of the modified nanofiltration membrane in the process of protein separation were analyzed by resistance superposition model. The results showed that the resistance of the modified nanofiltration membrane in the process of protein separation mainly came from the resistance of the membrane itself, which accounted for about 75.38% of the total resistance. The concentration polarization resistance and the boundary layer resistance were 15.08 and 9.53 respectively, which were lower than that of the original nanofiltration membrane (27.52 ~ 21.96). This shows that the modified membrane has better anti-pollution performance than the blank membrane, and has a good application prospect in the field of protein separation and biomedicine.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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