【作者】 崔霞；

【导师】 张捍民；

【作者基本信息】 大连理工大学 ， 环境工程， 2008， 硕士

【摘要】 膜生物反应器（membrane bioreactor，MBR）是将膜分离与生物工艺有机结合的一种新型技术，随着研究和开发的深入，该技术已经显示出较好的发展前景。但是，膜污染是MBR技术广泛推广的“瓶颈”。借助膜污染机理发展的预涂动态膜技术是膜表面物理改性的一种方法：将预涂剂吸附在基膜表面或者内部孔道，使基膜与污染物质不直接接触，从而有效延缓膜污染，并保护基膜、延长其使用寿命。因此，具有抗污染特性的新型预涂剂研究值得期待，有望利用预涂动态膜技术在一定程度上解决MBR工艺中的膜污染问题。本试验用乳液聚合法制备交联聚乙烯醇（Polyvinyl alcohol，PVA）微球，通过聚乙烯醇（PVA）与戊二醛（glutaraldehyde，GA）的乳化交联试验制备PVA微球粉末，并考察了W／O型乳状液内相的浓度、内外相体积比、乳化剂的性质和含量对形成稳定乳状液的影响。结果表明：（1）当乳状液内相PVA水溶液浓度为2.7％、内外相体积比为40：60、乳化剂司盘-80的浓度为1.30g／dL时，转速7000r／min，乳化10min条件下，乳状液的稳定性好。经过交联反应后形成的微球单分散性好、亲水性强、电负性高。（2）在乳化剂足量的前提下，提高乳化转速，制备的微球粒径减小；随着理论交联度的增大，微球粒径有变小的趋势，微球与水的接触角变大，而对Zeta电位影响不大。（3）微球表面有大量的羟基基团，由于缩醛反应进行的程度不完全，微球表面有残余醛基。为了进一步提高微球的抗污染特性，用NaBH₄还原残余醛基、将羧基接枝在微球表面。运用此两种方法对微球进行改性，并考察改性后微球的抗污染能力等。结果表明：（1）NaBH₄和PVA微球以无水乙醇溶液为反应介质，冰水浴连续搅拌发生还原反应。改性的PVA微球，其表面羟基数目提高23.2％。（2）丁二酸和PVA微球以乙腈溶液为反应介质，加热回流连续搅拌9h，脂化反应达到平衡。改性的PVA微球，电负性增强，对牛血清蛋白的吸附大大减少。更多还原

【Abstract】 The membrane bioreactor （MBR） is a new technology combined the wastewater biological treatment with the membrane separation technique, it showes great potential application in the wastewater treatment field. However, membrane fouling is a problem restricting the wild application of this process. Precoated dynamic membrane technology is used to modify membrane properties, which based on the membrane fouling mechanism: precoating regents were adsorbed on the surface or inner channels of membrane, so it can not been direct contact with fouling materials and its serving life was prolonged. Thus, it is necessary to prepare a novel precoating regent with anti-fouling characteristics to settle the problem of membrane fouling.In this thesis, cross-linked polyvinyl alcohol microspheres were prepared via an emulsion polymerization that PVA cross linked with glutaraldehyde which was extracted by anhydrous aether. Effects of concentration of PVA solution, the volume ratio of aqueous phase to oil phase, the selection of surface active agent （SAA） and its concentration on the stabilization of emulsion were studied. The results showed that:（1） When the concentration of PVA solution was 2.7%, the volume ratio of PVA solution/n-heptane was 40:60 and the concentration of span-80 was 1.30g/dL, the stirring speed 7000r/min with 10min, the emulsion was stabilized. Glutaraldehyde as a cross linker was dropped into the emulsion. After 3h cross-linked reaction in the condition of 50℃water bath heating and continuous stir, monodisperse PVA microspheres which contented our needs were prepared. The size of microspheres was 1850±100nm. The Zeta potential in the rage of -44mV--41mV , and the contact angle of PVA microspheres with distilled water was 16°-19°.（2） The size of microspheres diminished with the stirring speed increasing under the condition of enough span-80. It became smaller with the accretion of an aimed cross-linking degree which has little affection on surface charge. The contact angle of PVA microspheres with distilled water showed that these microspheres were hydrophilic.（3） The FTIR results suggested that hydroxy groups were great intensity with 100% of aimed cross-linking degrees and aldehyde group were residualed on the PVA microspheres.In order to further promote its anti-fouling characteristic, NaBH₄ was used to deoxidize aldehyde groups and the amber acid was grafted on the surface of PVA microspheres. The test methods and the characteristics of the modified PVA microspheres were investigated. The results showed that:（1） NaBH₄ was dissolved in anhydrous ethanol, and then reacted with PVA microspheres in ice-water bath for 3h. The mole ration of NaBH₄ and aldehyde group was 10:1. After reaction, PVA mirospheres modified by NaBH₄ were prepared. The number of hydroxy groups on the surface is improved from 2.11×10²⁰/g to 2.60×10²⁰/g.（2） Amber acid was dissolved in acetonitrile, and then reacted with PVA microspheres in the condition of heating reflux. The mole ration of Amber acid and hydroxy group was 10:1. The reaction reached equilibrium after 9h. PVA mirospheres modified by amber acid have a good anti-fouling characteristic to BSA.更多还原