【作者】 陈池；

【导师】 吕晓龙；

【作者基本信息】 天津工业大学 ， 材料学， 2004， 硕士

【摘要】 聚偏氟乙烯（PVDF）中空纤维多孔膜具有优良的性能，然而由于其表面的疏水性，在用于水相体系分离时，仍会产生吸附污染，导致膜通量和分离效率下降，应用范围受到限制。本文采用制备中空纤维复合膜的方法，在不改变PVDF基膜材料本体性能的基础上，发挥基膜材料和分离功能层膜材料的优点，得到高分离功能、高透过通量的智能复合膜。 采用表面化学接枝的方法制备PVDF-g-PAMPS中空纤维接枝复合膜。首先对PVDF中空纤维膜进行强碱及强氧化剂处理，使基膜表面活化。处理条件为：KOH浓度2.5mol／L，KMnO₄浓度3wt％，反应温度60℃，反应时间10～30min，溶液中加入500mg／150ml四丁基溴化铵。然后进行接枝聚合反应，接枝单体选用2-丙烯酰胺-2-甲基丙磺酸（AMPS）。接枝聚合反应体系为：AMPS单体溶液浓度1.5mol／L，硫酸亚铁铵浓度4.2×10^-3mol／L，水浴恒温60℃，反应时间3hrs，体系中加入引发剂（CAN）500mg／150ml。通过改变碱处理的时间，可以得到不同接枝率的复合膜。通过红外光谱（FTIR）、光电子能谱（XPS）、扫描电镜（SEM）等分析手段证实了膜表面接枝共聚物的存在。PVDF-g-PAMPS中空纤维复合膜是具有环境响应功能的智能膜。PAMPS分子链的构象随溶液环境（pH值、离子强度等）的变化而变化，从而影响膜的渗透通量和选择透过能力。在低离子强度（高pH值）溶液中，分子链伸展，膜通量较小；而在高离子强度（低pH值）溶液中，分子链收缩，膜通量较大。用接枝复合膜过滤BSA溶液，在等电点（pH=4.8）处的截留率最高，而在等电点两侧，截留率有所下降；在低离子强度溶液中，BSA截留率较高，而在高离子强度溶液中，BSA截留率较低。 采用界面聚合法制备PAMPS／PVDF中空纤维凝胶复合膜。先对PVDF中空纤维膜进行碱处理，使基膜表面生成碳碳双键。碱处理条件为：KOH浓度2.5mol／L，反应温度60℃，反应时间10min，溶液中加入500mg／150ml四丁基溴化铵。将经过碱处理的PVDF中空纤维膜置于浓度为1.5mol／L的AMPS单体溶液中浸泡3hrs，取出并排除过量溶液后，放入含交联剂MBAA（浓度分别为0.03、0.06、0.09 mol／L）和引发剂K₂S₂O₈（0.0075 mol／L）的交联反应体系中，恒温60℃，反应40～60min，得到凝胶复合膜，且基膜表面与凝胶层以化学键结合。通过傅立叶红外光谱（FTIR）分析和扫描电子显微镜（SEM）的观察，证实了PVDF基膜表面PAMPS凝胶层的存在。PAMPS／PVDF中空纤维凝胶复合膜同样具有环境响应的智能性。PAMPS凝胶层在不同的溶液环境中H值、离于强度等)中，表现出可逆的溶胀一收缩变化。在低离子强度（高pH值）溶液中，凝胶层溶胀，膜通量变小：而在高离子强度则pH值)溶液中，凝胶层收缩，膜通量变大。在凝胶复合膜过滤BSA溶液的实验中，离子强度减小，截留率升高；离子强度增大，截留率下降。 PVDF基膜表面引入PAMPS长链分子或者PAMPS凝胶层，亲水性大为改善，抗污染能力明显提高。在蛋白质膜分离过程中，膜表面不易产生吸附污染，膜通量衰减程度较小。更多还原

【Abstract】 Poly(vinylidene fluoride) (PVDF) hollow-fiber porous membranes have excellent performances. But adsorption fouling will still be created on the hydrophobic surface when the membranes are used in aqueous solution separation systems. This can cause the decrease of the permeate flux and separation efficiency, thus the applications of the membranes are limited. The preparation of composite membranes in this dissertation can optimize the separation function and improve the antifouling ability of the membranes while not change the properties of the PVDF radicle membranes.The PVDF-g-PAMPS hollow-fiber grafted composite membrane was prepared through surface chemical grafting. First, the treatment with strong alkali and strong oxidant to PVDF hollow-fiber membrane was carried out to activate the surface. The reaction condition was: [KOH]=2.5mol/L, [KMnO4]=3wt%, [TBAB]= 500mg/150ml, T=60 C, t=10~30min. Second, grafting copolymerization reaction was carried out. AMPS was chosen as hydrophilic monomer. Reaction system was: [AMPS]=1.5mol/L, [FAS]=4.3 10-3mol/L, [CAN]=500mg/150ml, T=60 C, t=3hr. Grafted copolymers on the surface of composite membrane were verified by FTIR, XPS and SEM.The PVDF-g-PAMPS composite membrane is a kind of intelligent membrane with environment responsibilities. The structures of PAMPS molecule chains change along with the changes of solution environments (pH and ionic strength (I)) and thus affect the water flux and selective permeability of the composite membrane. The water flux decreases with increasing pH and increases with 1. The BSA rejection is highest at the isoelectric point (IEP) (4.8), while decreases on both sides of IEP. The BSA rejection increases as I decreases.PAMPS/PVDF hollow-fiber gel composite membrane was prepared through interfacial polymerization. First, the treatment with strong alkali to PVDF hollow-fiber membrane was carried out to create C=C bonds on the membrane surface. The treatment condition was: [KOH]=2.5mol/L, [TBAB]= 500mg/150ml, T=60 C,t=10min. Then the treated membrane was dipped in the AMPS monomer solution([1.5mol/L]) for 3hrs. Crosslinking copolymerization reaction was followed. The crosslinking system was: [MBAA]=0.03,0.06,0.09mol/L, [K2S2O8]=0.0075 mol/L, T=60 C, t=40~60min. The existence of PAMPS gel layer on the surface of composite membrane was confirmed by FTIR and SEM.PAMPS/PVDF hollow-fiber gel composite membrane also has environment responsibilities. The PAMPS gel layer swells-shrinks reversibly as the solution environments (pH and I) change. The water flux increases with decreasing pH and decreases with 7. The BSA rejection increases as /decreases.The hydrophilicity of the surface of PVDF hollow-fiber membranes has been greatly improved and the antifouling ability increased obviously. Adsorption fouling can not be created easily and the permeate flux decreases limitedly.更多还原