【作者】 张倩；

【导师】 孟琴；

【作者基本信息】 浙江大学 ， 生物化工， 2014， 硕士

【摘要】 聚砜(PSU)超滤膜是一种具有选择性分离功能的高分子膜,广泛应用于各领域。然而,聚砜膜较强的疏水性导致其极易被污染,使其在进一步的应用拓展中受到限制。提高聚砜膜抗污染性主要的方法是加强其亲水性。虽然在聚砜超滤膜亲水改性方面已有较多研究,但仍未找到提高其抗污染性能的长期有效途径。本文主要探索了两性离子聚合物(如磺基甜菜碱甲基丙烯酸酯,SBMA)在聚砜分子上进行接枝共聚(graft copolymerization,聚合物名称中简写为g)反应,以及使用该共聚物材料制作平板膜和中空纤维膜的方法,并对两种膜材料进行了亲水性和抗污染性能考评。同时选用上述制备的中空纤维膜分离实验室配置油水乳液和工业含油废水,进一步对其抗污染能力进行评估。首先,本实验筛选出二甲亚砜(DMSO)为反应溶剂,实现了均相反应体系内,SBMA在PSU分子上的接枝反应。通过红外光谱及元素分析考察PSU-g-SBMA共聚产物的官能团和元素含量,调节反应温度和反应物添加比例,确定较优反应条件为:T=65℃,SBMA CMPSU(mol/mol)=4:1,此时 SBMA接枝率达到75.8%。其次,将PSU-g-SBMA与PSU共混制备铸膜液,经相转化法制备超滤共混改性平板膜(下称PSU-g-SBMA平板膜)并对其形貌和抗蛋白污染能力进行表征。扫描电子显微镜(SEM)观测显示该膜呈现典型超滤膜的指状大孔结构;静态水接触角为54°(PSU平板膜为94°)。蛋白质截留和吸附实验表明该膜有效降低了蛋白的吸附。且该膜在1 g/L和10 g/LBSA溶液污染1h后,水通量恢复率(Flux Recovery Ratio,FRR)分别达到100%和61%。由此可见,SBMA共混改性有效提高了 PSU膜的亲水性和抗污染能力。随后,采用湿法纺丝法制备PSU-g-SBMA共混改性超滤中空纤维膜(下文称PSU-g-SBMA中空纤维膜),通过扫描电镜(SEM)、X射线光电子能谱(XPS)、静态蛋白吸附和超滤实验考察其亲水改性情况及抗污染性能,分析结果表明PSU-g-SBMA中空纤维膜同样具有良好的抗污染性。将该中空纤维膜进一步用于分离实验室制备油水乳液,发现该膜在长期和短期超滤过程中均具有较好的抗污染和分离能力。最后,研究了 PSU-g-SBMA中空纤维膜用于处理上海某钢铁厂煤焦油废水的可行性。先通过破乳和芬顿反应对废水进行预处理,将废水COD从18000 mg/L降至11000 mg/L左右。然后采用PSU-g-SBMA中空纤维膜进行超滤分离,使废水的COD下降了 2500 mg/L左右。PSU-g-SBMA中空纤维膜在进行短时间(1 h)和长时间(6h)的超滤后,通过去离子水清洗后的水通量恢复率达到95%以上,并且可反复使用,说明PSU-g-SBMA中空纤维膜对于煤焦油废水具有较高抗污染性能和较好的处理能力。综上所述,本研究实现了 PSU和SBMA的均相接枝反应,并制备得PSU-g-SBMA平板膜和中空纤维膜,显著提高了 PSU膜的抗污染性能,拓展了其在含油废水处理方面的应用,为两性离子改性超滤膜的工业化生产奠定了技术基础。更多还原

【Abstract】 Polysulfone membranewith good thermal and dimensional stability and excellent mechanical property has been widely applied in many fields.However,the hydrophobic property of polysulfone results in membrane fouling and limits its further development.To improve the antifouling property of polysulfone membrane,great efforts have been given.Zwitterionic polymer,being of both super hydrophobicity and unti-fouling ability at surface modification of the material surface,would give a promising feasibility in solving the problem mentioned above.However,the surface modification of materials showed the disadvantages on the low reaction efficiency and the difficult scale-up.In this study,N-Methyl-2-PyrrolidonE(NMP))was carefully selected to be the solvent for both sulfobetaine methacrylate(SBMA)and polysulfone(PSU).A homogeneous grafting reaction of SBMA onto PSU occurred with the presence of the initiator of chloromethyl group.The reaction operation conditions were optimized as followings:temperature of 65℃ and the reactant ratio of SBMA:CMPSU(mol/mol)=4:1,which provided a grafting ratio of 75.8%.The immersion precipitation phase transformation method was used to prepare the flat PSU-g-SBMA ultrafiltration membranes via blending of PSU with the graft product.The hybrid membranes showed finger-like pores in the section surface,a typical structure for ultrafiltration membrane.Most importantly,these hybrid membranes exhibited the BSA(bovine serum albumin)rejection of>90%and fibrinogen rejection of 99%.Additional characterization further confirmed that this membrane was of a greatly improved hydrophilicity and antifouling property by showing the contact angelof around54°,static BSA adsorption ofbelow 10 μg/cm2,and ratio of flux recovery of above 95%and 61%for the contamination by 1 g/L BSA or for 10g/L BSA,respectively.PSU-g-SBMA hybrid hollow fiber membrane was further prepared by wet spinning method.Both the static and ultrafiltration contamination of BSA confirmed the antifouling property of PSU-g-SBMA hybrid hollow fiber membrane in similar to at the antifouling performance on the corresponding hybrid flat membrane.The hollow fiber membrane is further applied in the separation of lab-made oil-water emulsions,and a relatively good performance is seen in its antifouling and separation ability while conducting long term and short term ultrafiltration.Finally,PSU-g-SBMA hybrid hollow fiber membrane was applied in separation of industrial wastewater.After the pretreatment with deemulsification and phenton reaction,the wastewater was ultrafiltrated across this membrane,which caused a reduction of with the COD reduction by 2500mg/L,and FRR of above 95%for water flushing post to whatever short(1 h)or long term(6 h)ultrafiltration.Hence,it could be concluded that PSU-g-SBMA hybrid hollow fiber membrane performed a good separation efficiency in treatmet of real wastewater.In conclusion,this study address the potential application of zwitterions in modification of the industrialized membrane.更多还原