GO-PEG共混改性PVDF超滤膜制备及抗污染性能研究

发布时间：2018-03-12 12:28

本文选题：PVDF　切入点：GO　出处：《天津工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：PVDF因其优异的化学稳定性、耐热性及其良好的成膜性能而被广泛的应用于超滤膜的制备。然而由于其强疏水性,使其在使用过程中极易发生膜污染从而造成通量的衰减。本文通过化学方法将亲水性无机纳米碳材料氧化石墨烯(GO)和亲水改性剂聚乙二醇(PEG)通过接枝制备了 GO-PEG复合材料(f-GO),并将其作为添加剂共混于PVDF铸膜液中,利用浸没沉淀法制备出拥有较强抗污染性能的PVDF复合超滤膜。本研究利用FTIR、静态接触角、SEM、AFM测试,考察了 GO-PEG对PVDF膜的表面化学组成、亲水性、孔道结构及表面形貌的影响。结果表明,随着GO和f-GO的添加量从Owt%增大到1.Owt%时,PVDF膜表面的亲水性得到了增强,并且添加f-GO的PVDF膜表现了更佳的亲水性,膜表面接触角从基膜的72°降低到59°。另外,添加f-GO,PVDF膜的孔道结构也发生了不同于基膜和GO复合膜的变化,孔径增大,表面孔隙率明显增加。膜表面粗糙度也较基膜有所降低,基膜的Sa为118nm,f-GO复合膜的粗糙度最低达到了 71.1nm。当f-GO添加量从Owt%增加到0.5wt%时,PVDF膜的纯水通量表现出了先增大后减小的趋势,当添加量为0.5wt%时,膜纯水通量达到最大,为93L·m-2·h·1,增加了100%。复合膜的BSA截留率并没有太大变化,都可达到95%以上。当f-GO的添加量从Owt%增加到1.Owt%时,PVDF膜的抗污染性能也受到了不同的影响。对于BSA、HA等有机污染,f-GO复合膜膜总阻力和不可逆阻力均要低于PVDF基膜和GO复合膜。当添加量为0.5wt%时,膜阻力达到最低。对于BSA、HA污染,不可逆阻力相比于基膜降低了 83.7%、84.4%。膜污染后,经过简单的表面清洗,f-GO复合膜仍然可以获得很高的通量恢复率(FRR)。当添加量为0.5wt%时,拥有最高的FRR,BSA污染的FRR为78%,HA污染的FRR为74%,而PVDF基膜却只有50%和47%的FRR。通过复合膜多周期运行,膜通量随着时间的变化结果显示,f-GO复合膜经过三个周期的运行后,无论是BSA通量,还是纯水通量,复合膜仍然保持着很高的渗透性,并且逐渐的膜通量达到稳定,不再衰减,而PVDF基膜的通量衰减严重。以铜绿假单胞菌为目标菌种,研究膜的抑菌性和抗生物污染性能。在复合膜抑菌性方面的研究发现,f-GO和GO复合膜的抑菌性均要好于PVDF基膜,但是f-GO和GO复合膜在抑菌性方面并没有表现出太大的差异。相比于PVDF基膜,当添加量为0.5wt%时,f-GO复合膜的不可逆阻力降低了 87%。并且经菌液污染后,膜表面经过相同的去离子水清洗,f-GO复合膜的通量恢复率即可达到80%,而基膜通量恢复率只有60%。综合以上结果说明,添加f-GO复合材料后,PVDF膜的亲水性和抗有机污染性能得到明显的强化。而尽管f-GO复合膜抑菌性能并没有表现出比GO复合膜更好的效果,但是f-GO复合膜的抗生物污染性能得到了有效的增强。
[Abstract]:PVDF is widely used in the preparation of ultrafiltration membranes because of its excellent chemical stability, heat resistance and good film forming properties. However, because of its strong hydrophobicity, In this paper, the hydrophilic inorganic nano-carbon materials graphene oxide (GOO) and hydrophilic modifier polyethylene glycol (PEG) were grafted to prepare GO-PEG by chemical method. The composite materials were mixed in PVDF casting solution as additives. PVDF composite ultrafiltration membrane was prepared by immersion precipitation method. The surface chemical composition and hydrophilicity of GO-PEG on PVDF membrane were investigated by FTIR and static contact angle test. The results showed that the hydrophilicity of PVDF membrane was enhanced with the increase of go and f-go content from Owt% to 1.Owt%, and the hydrophilicity of PVDF membrane with f-go was better. The surface contact angle of the membrane was reduced from 72 掳to 59 掳. In addition, the pore structure of the PVDF membrane was different from that of the base film and go composite membrane. The pore size increased and the surface porosity increased obviously. The surface roughness of the membrane was also lower than that of the base film. The lowest roughness of the composite membrane was 71.1 nm. When the amount of f-go was increased from Owt% to 0.5wt%, the pure water flux of PVDF membrane increased first and then decreased, and the pure water flux of PVDF membrane reached the maximum when the addition amount was 0.5wt%. 93L 路m -2 路h 路h 路1, increased 100%. The BSA rejection rate of the composite membrane did not change significantly. When the amount of f-go was increased from Owt% to 1.Owt%, the antifouling performance of PVDF membrane was also affected. The total resistance and irreversible resistance of PVDF / go composite membrane were lower than those of PVDF and go membranes. When the addition amount is 0.5 wt%, The membrane resistance reached the lowest. For BSA-HA pollution, the irreversible resistance was 83.7% lower than that of the base membrane. After membrane fouling, a high flux recovery rate of FRRRN could still be obtained after simple surface cleaning. When the amount of BSA-HA was 0.5 wt%, The FRR with the highest FRRN BSA pollution was 78g HA contaminated FRR 74, while the PVDF base membrane had only 50% and 47% FRRs.Through the multiperiod operation of the composite membrane, the change of membrane flux with time showed that the f-go composite membrane had run through three cycles, whether BSA flux or not. The membrane flux is still pure water, and the membrane flux is stable, but the flux of PVDF base membrane decays seriously. Pseudomonas aeruginosa is taken as the target strain. The bacteriostasis and anti-fouling properties of the composite membrane were studied. It was found that the bacteriostasis of the composite membrane was better than that of the PVDF substrate membrane, and the bacteriostasis of the composite membrane was better than that of the PVDF substrate membrane. However, the bacteriostatic properties of f-GO and go composite membranes were not significantly different from those of PVDF. Compared with PVDF substrate, the irreversible resistance of f-go / go composite membranes was reduced by 87wt% when the dosage was 0.5 wt%. After the same deionized water cleaning, the flux recovery rate of the membrane can reach 80%, while the flux recovery rate of the base membrane is only 60%. The hydrophilicity and organic pollution resistance of PVDF membrane were obviously enhanced after adding f-go composite material, but the bacteriostatic property of f-go composite membrane was not better than that of go composite membrane. But the anti-pollution performance of F-go composite membrane was enhanced effectively.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893;X703

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