基于HBPs接枝的PVDF膜亲水改性及抗污染性能
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摘要
在聚偏氟乙烯(PVDF)微滤膜表面接枝超支化聚合物聚乙烯亚胺(HPEI),并通过环氧丙醇与氨基的开环反应在PVDF膜表面形成高密度的多羟基结构,实现PVDF膜的亲水改性.实验对膜的表面亲水性、抗粘附性能和抗污染性能进行表征,并采用原子力显微镜(AFM)测量膜与污染物探针之间的粘附力以进一步探究改性膜的抗污染机理.实验结果显示,改性后,PVDF膜的接触角从85°减小至42°,润湿时间从20s缩短至10s,表面亲水性显著提高;在静态吸附实验中,改性膜表面粘附的蛋白质和多糖数量明显减少;在动态污染实验中,改性膜的水通量恢复率(FRR)较高,不可逆通量下降率(IFR)较低,说明其较强的抗污染性能.AFM界面粘附力的测试结果表明污染物探针与改性膜面的粘附力较弱,进一步证实改性膜表面丰富的亲水基团以及超支化结构的位阻效应可以有效改善PVDF膜的抗污染性能.
Hyperbranched polyethyleneimine(HPEI) was grafted on the surface of polyvinylidene fluoride(PVDF) microfiltration membrane, and a high-density hydroxyl structure was formed on the surface of PVDF membrane by the ring-opening reaction of glycidol and the terminal amino groups. Contact angle tests confirmed the improved hydrophilicity of the modified membrane. After modification, the contact angle of PVDF membrane was decreased to 42° with initial 85° and the wetting time was shortened to 10 s with initial 20 s. Static adsorption tests demonstrated that the modified membrane had much less amount of proteins and polysaccharides on the membrane surface compared to the control. Dynamic fouling experiments showed that the modified membrane had significantly higher water flux recovery ratio and lower relative fouled flux ratio in comparison with the pristine PVDF membrane. AFM(Atomic Forces atomic force microscopy) contact force measurements exhibited weaker foulant-membrane interactions and foulant-foulant interactions for the modified membrane, which can be attributed to the abundant hydrophilic groups on the membrane surface and steric effect of the hyperbranched structure.
Hyperbranched polyethyleneimine(HPEI) was grafted on the surface of polyvinylidene fluoride(PVDF) microfiltration membrane, and a high-density hydroxyl structure was formed on the surface of PVDF membrane by the ring-opening reaction of glycidol and the terminal amino groups. Contact angle tests confirmed the improved hydrophilicity of the modified membrane. After modification, the contact angle of PVDF membrane was decreased to 42° with initial 85° and the wetting time was shortened to 10 s with initial 20 s. Static adsorption tests demonstrated that the modified membrane had much less amount of proteins and polysaccharides on the membrane surface compared to the control. Dynamic fouling experiments showed that the modified membrane had significantly higher water flux recovery ratio and lower relative fouled flux ratio in comparison with the pristine PVDF membrane. AFM(Atomic Forces atomic force microscopy) contact force measurements exhibited weaker foulant-membrane interactions and foulant-foulant interactions for the modified membrane, which can be attributed to the abundant hydrophilic groups on the membrane surface and steric effect of the hyperbranched structure.
引文
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[2] Kang X, Wang X M, Huang X, et al. Combined effect of membrane and foulant hydrophobicity and surface charge on adsorptive fouling during microfiltration[J]. Journal of Membrane Science, 2011,373(1):140-151.
[3] Wang Q Y, Zeng H, Wu Z C, et al. Impact of sodium hypochlorite cleaning on the surface properties and performance of PVDF membranes[J]. Applied Surface Science, 2018:428.
[4] Liu C H, Lee J, Ma J, et al. Antifouling thin-film composite membranes by controlled architecture of zwitterionic polymer brush layer[J]. Environmental Science&Technology, 2017,51(4):2161.
[5] Kobayashi M, Terayama Y, Yamaguchi H, et al. Wettability and antifouling behavior on the surfaces of superhydrophilic polymer brushes[J]. Langmuir, 2012,28(18):7212.
[6] Venault A, Huang W Y, Hsiao S W, et al. Zwitterionic modifications for enhancing the general antifouling properties of polyvinylidene fluoride membranes[J]. Langmuir, 2016,32(16):4113.
[7]潘婷,李方,杜春慧,等.PVDF超滤膜进行聚乙二醇甲基丙烯酸甲酯(PEGMA)紫外光照射接枝的膜面表征与抗污染分析[J].环境科学学报, 2015,35(4):1061-1066.Pan T, Li F, Du C H, et al. Surface characterization and anti-fouling performance analysis of PVDF ultrafiltration membrane modified by UV-photo grafting poly(ethylene glycol)methacrylate(PEGMA)[J].Chinese Journal of Environmental Engineering, 2015,35(4):1061-1066.
[8] Zhang Y, Wang Z, Lin W F, et al. A facile method for polyamide membrane modification by poly(sulfobetaine methacrylate)to improve fouling resistance[J]. Journal of Membrane Science, 2013,446:164-170.
[9] Meng J Q, Cao J J, Xu R S, et al. Hyperbranched grafting enabling simultaneous enhancement of the boric acid uptake and the adsorption rate of a complexing membrane[J]. Journal of Materials Chemistry A,2016,4(30):11656-11665.
[10] Calderón M, Quadir M A, Sharma S K, et al. Dendritic polyglycerols for biomedical applications[J]. Advanced Materials, 2010,22(2):190-218.
[11] Arslan B, Egerton K, Zhang X, et al. The effects of the surface morphology and conformations of lignocellulosic biomass biopolymers on their nanoscale interactions to hydrophobic selfassembled monolayers[J]. Langmuir, 2017,33(27):6857-6868.
[12] Szczerbińska J, Kujawski W, Arszyńska J M, et al. Assessment of air-gap membrane distillation with hydrophobic porous membranes utilized for damaged paintings humidification[J]. Journal of Membrane Science, 2017,538:1-8.
[13] Tiraferri A, Kang Y, P Giannelis E, et al. Superhydrophilic thin-film composite forward osmosis membranes for organic fouling control:fouling behavior and antifouling mechanisms[J]. Environmental Science&Technology, 2012,46(20):11135-11144.
[14]吴公政,王磊,王珮,等.超滤膜材料对SiO2-有机物膜污染行为的影响[J].中国环境科学, 2019,39(4):1511-1515.Wu G Z, Wang L, Wang P, et al. The effect of ultrafiltration membrane materials on the combined fouling behavior of SiO2-organic coexist foulants[J]. China Environmental Science, 2019,39(4):1511-1515.
[15] Meng J Q, Cao J J, Xu R S, et al. Hyperbranched grafting enabling simultaneous enhancement of the boric acid uptake and the adsorption rate of a complexing membrane[J]. Journal of Materials Chemistry A,2016,4(30):11656-11665.
[16] Ma Z, Lu X L, Wu C R, et al. Functional surface modification of PVDF membrane for chemical pulse cleaning[J]. Journal of Membrane Science, 2017,524:389-399.
[17] Vatanpour V, Esmaeili M. Fouling reduction and retention increment of polyethersulfone nanofiltration membranes embedded by amine-functionalized multi-walled carbon nanotubes[J]. Journal of Membrane Science, 2014,466:70-81.
[18] Zhao X Y, Ma J, Wang Z H, et al. Hyperbranched-polymer functionalized multi-walled carbon nanotubes for poly(vinylidene fluoride)membranes:From dispersion to blended fouling-control membrane[J]. Desalination, 2012,303:29-38.
[19] Yang W J, Neoh K G, Kang E T, et al. Stainless steel surfaces with thiol-terminated hyperbranched polymers for functionalization via thiol-based chemistry[J]. Polymer Chemistry, 2013,4(10):3105-3115.
[20] Liu Y, Su Y L, Zhao X T, et al. Improved antifouling properties of polyethersulfone membrane by blending the amphiphilic surface modifier with crosslinked hydrophobic segments[J]. Journal of Membrane Science, 2015,486:195-206.
[21] Castrillón S R V, Lu X L, Shaffer D L, et al. Amine enrichment and poly(ethylene glycol)(PEG)surface modification of thin-film composite forward osmosis membranes for organic fouling control[J].Journal of Membrane Science, 2014,450(2):331-339.
[22] Wang L, Miao R, Wang X D, et al. Fouling behavior of typical organic foulants in polyvinylidene fluoride ultrafiltration membranes:characterization from microforces[J]. Environmental Science&Technology, 2013,47(8):3708-3714.
[23] Conrad S, Markus B, Rainer H. Self-assembled monolayers of dendritic polyglycerol derivatives on gold that resist the adsorption of proteins[J]. Chemistry, 2004,10(11):2831–2838.