【作者】 韩润林；

【导师】 蹇锡高； 张守海；

【作者基本信息】 大连理工大学 ， 膜科学与技术， 2011， 博士

【摘要】 含二氮杂萘酮联苯结构的聚芳醚系列材料是具有优异耐热性的可溶性热塑性树脂,它们具有高的玻璃化转变温度、成膜性、机械强度和化学稳定性。杂萘联苯共聚醚砜(PPBES)除了具有以上材料的共同优点外,还具有良好的韧性,是潜在的超滤膜材料。而本组开发的季铵化杂萘联苯聚醚砜酮(QAPPESK)纳滤膜对高价金属阳离子具有较高的截留率,且该膜具有较高的通量和热稳定性,在某些废水处理领域中具有非常大的应用潜力。本文以PPBES为膜材料,水为凝胶剂采用相转化法制备超滤膜。首先采用溶解度参数理论选择了PPBES可能的制膜溶剂。然后考察了几种常见的溶剂如N,N-二甲基乙酰胺(DMAc)、N-甲基吡咯烷酮(NMP)、N,N-二甲基甲酰胺(DMF)、吡啶(Pyridine)、二甲基亚砜(DMSO)、四氢呋喃(THF)对膜性能的影响。实验发现仅有DMAc、NMP和Pyridine可以用作制膜溶剂。以DMAc为制膜溶剂所成的膜具有较好的综合性能,因此DMAc被选作超滤膜的制膜溶剂。采用浊点滴定法研究了五种有机小分子添加剂与PPBES/DMAc体系的相容性和沉淀能力,并研究了这五种添加剂对超滤膜性能和形貌的影响。结果发现,添加剂的极性和挥发性对膜的性能和形貌影响较大。添加剂的极性越强,与聚合物的亲和性越差,膜断面越倾向于形成海绵状结构,且使得膜通量较高。而挥发性强的添加剂在停留蒸发阶段更容易从膜中逸出,使得膜孔致密且断面膜孔较小,形成的膜通量较低。为了得到较优性能的PPBES超滤膜,本文详细考察了聚合物浓度、凝胶浴温度、停留蒸发时间等对超滤膜性能的影响。在优化条件下制备了PPBES超滤膜,在0.1 MPa,20℃条件下,所制的超滤膜纯水通量约430 L/m2h,对PEG10000的截留率在93%以上以EGME作为有机添加剂,LiC1作为无机添加剂制备四元体系铸膜液,制备小孔径超滤膜。最终选定聚合物含量20%、EGME含量8%、LiCl含量2%,成功制备纯水通量为122 L/m2h、对PEG1000截留率达到100%的低截留分子量超滤膜。由于PPBES具有良好的机械性能特别是韧性,PPBES超滤膜适合用作复合膜的支撑底膜。本文以PPBES超滤膜为底膜,通过界面聚合的方法在其上表面反应生成超薄的聚哌嗪酰胺功能层来制备纳滤膜。系统地考察了界面聚合的条件,确定了最优的水相单体哌嗪和油相单体均苯三甲酰氯(TMC)浓度、水相浸渍时间、反应时间、烘焙温度和烘焙时间。制备出的纳滤膜具有较高的通量75 L/m2h和对Na2SO4较高的截留率97.5%。其对1g/L的Na2SO4测试结果表明,当操作温度从18℃升至85℃,纳滤膜的通量从61 L/m2h升高至290 L/m2h,而截留率仅下降了3.8%。低截留分子量的PPBES超滤膜的对某些染料分子截留率较高,而对无机盐没有截留,可以大大降低处理废水的渗透压。因此可以用于盐和染料分离,适合用于染料工业废水的处理和印染过程中染料的浓缩。本文采用了对PEG1000的截留率为100%的低截留分子量超滤膜对具有代表性的染料模拟废水进行了处理。实验表明,在室温0.2 MPa下,该膜对直接染料刚果红(Congo Red)、硫化染料硫化黑(Sulfur Black B)和阴离子染料龙胆紫(Gentian Violet)的截留率为100%。该膜对活性染料活性黄(C. I. Reactive Yellow 86)、分散染料分散红(C.I. Disperse Red 73)和阳离子染料酸性铬兰(Acid Chrome Blue K)的截留率分别为79%、54%和43%。除分散染料外,其他处理过程中膜的通量都达到87 L/m2h以上,具有较好处理能力。为了进一步提高膜对活性染料、分散染料和阳离子染料的截留率,采用聚哌嗪酰胺/PPBES复合纳滤膜来处理,取得了较好的效果。对超滤膜和纳滤膜的在高温环境中的使用稳定性也进行了相应的考察。结果表明,自制的超滤膜和纳滤膜都具有良好的耐热性。选择几种实验室自制的纳滤膜对大连某染料厂的硫化黑废水进行了处理。实验发现,荷负电的界面聚合聚哌嗪酰胺复合纳滤膜和涂覆的磺化复合纳滤膜的通量较低。而荷正电的季铵化纳滤膜(QAPPESK)在使用过程中表现出了较高的通量和较高的染料截留率,可以将染料与废水中无机盐进行分离,大大简化了工艺流程且能降低成本。在废水出水温度60℃的条件下对该废水进行处理时,在0.6 MPa下,膜的通量为14.5L/m2h,对硫化黑染料的截留率为92.3%,而对无机盐的截留率为10%。膜在60℃下使用72 h性能没有下降,因此该膜适合用于将染料和无机盐分离,从而达到工厂回收无机盐和降低污染的要求。更多还原

【Abstract】 Recently, a series of novel poly (aryl ether sulfone) materials containing phthalazinone moiety are high-performance engineering thermoplastics with reasonable solubility and excellent thermal property. They possess high glass-transition temperature, membrane forming property, mechanical performance and chemical stability. Copoly (phthalazinone ether sulfone) (PPBES) which has good flexibility is a potential material for ultrafiltration (UF) membrane and support membrane of composite membrane. Positively charged QAPPESK nanofiltration membrane made in our laboratory has low rejection of high-valent cations, high flux and good thermal stability which possesses great potential in some wastewater treatment applications.PPBES UF membrane is prepared with phase inversion method and water is used in coagulation bath. The choice of solvent of the casting solution is based on solubility theory. Several solvents such as DMAc, NMP, DMF, Pyridine, DMSO and THF are tried to prepare casting solution. Only DMAc, NMP and Pyridine can be used according the solubility experiment. DMAc is chosen because the membrane formed has good performance. By using turbidity titration to study the effects of additives for the thermodynamic of the casting solution and the compatibility and precipitation capacity of five non-solvent additives on PPBES/DMAc solution are determined. Effect of different additives on membrane performance and morphology are studied. The polarity and volatility of the additive affect the membrane perfprmance and morphology obviously. Higher polarity causes the worse compatability with membrane material PPBES caused sponge-like structure and high flux. Additive with strong volatility is ready to escape and the membrane formed has dense skin, low flux and small pores.The influences of polymer concentration, coagulation temperature and evaporation time on UF membranes performance are studied. Under optimized condition, the flux of the membrane is 430 L/m2h and rejection of PEG 10000 is about 93% at 0.1 MPa and 20℃. By using EGME as organic additive, LiCl as inorganic additive, a quaternary-system casting solution was prepared to make PPBES UF membrane with low molecular weight cut-off (MWCO). When the polymer content is 20%, EGME content is 8% and the LiCl content is 8% , the PPBES UF membrane with low MWCO is successfully prepared which has high flux of 122 L/m2h and high PEG1000 rejection rate of 100%. Because of the excellent mechanical performance and flexibility of PPBES, PPBES UF membrane is suited to be used as the substrate of PPBES composte NF membrane. In this work, Poly (piperazinamide) NF membrane is prepared on the PPBES UF membrane with interfacial polymerization method. Reaction conditions including monomer concentrations, immersion time in water phase, reaction time, post-treatment temperature and time are optimized. PPBES composite NF membrane prepared has high flux (75 L/m2h) and high rejection of Na2SO4 (97.5%). When tested with 1 g/L Na2SO4 solution, the membrane flux is increased from 61 to 290 L/m2h while the rejection decreases 3.8% only as the operation temperature elevated from 18℃to 85℃。PPBES UF membrane with low MWCO has high rejection of organic material but can not reject inorganic salts, which will greatly decline the osmotic pressure. So it is suitable be ultilized in separation of salt and organic material, especially in treatment of dye production and dyeing wastewater. The simulative dye wastewater treatment is taken with the low MWCO PPBES UF membrane. The rejections of direct dye (Congo Red), anion dye (Gentian Violet) and sulfur dye (Sulfur Black B) are all 100%. The rejections of reactive dye (Reactive Yellow 86), disperse dye (Disperse Red 73) and cationic dye (Acid Chrome Blue K) are 79%, 54% and 43% , respectively. All the membrane fluxes are higher than 87 L/m2h except for disperse dye. In order to improve the rejection of Reactive Yellow 86, Disperse Red 73 and Acid Chrome Blue K, poly (piperzinamide) NF membrane is ultiliezd and shows good performance. The thermal stability of PPBES UF membrane and composite NF membrane is studied and the result demonstrates that they possess excellent themal resistance.Several NF membrane made in our laboratory are tried in the treatment of sulfur black dye wastewater of a Dalian factory. The negatively charged poly (piperzinamide)/PPBES NF membrane and SPPES/PPESK NF membrane show very low flux in operation while the positively charged QAPPESK NF membrane shows high flux and high dye rejection. The QAPPESK membrane has low rejection of divalent ions and can be used to separate and reuse dye and salts. At 60℃and 0.6 MPa, the membrane flux is 14.5 L/m2h, rejection of sulfur black dye is 92.3% while salt rejection is only 10%. The membrane performance does not decline in 72 h operation at 60℃. So the membrane is a suitable choice for this wastewater treatment and can accomplish the claim of separation of dye and inorganic salts.更多还原