【作者】 杨峰；

【导师】 胡小玲；

【作者基本信息】 西北工业大学 ， 应用化学， 2007， 硕士

【摘要】 膜分离技术是一种分离效率高、能耗低、环境友好的新型分离技术，在工业上已得到广泛应用和发展。传统的纳滤膜制备方法中，总是存在小孔难致、溶剂残留、孔隙率低、孔结构不均匀等问题。针对此类问题，本论文采用超临界CO₂流体致孔技术，对聚乙烯醇进行发泡致孔，制备了孔结构优良的聚乙烯醇纳滤膜，并就所制备的纳滤膜在红霉素的分离纯化方面的应用进行了探讨。 研究中以聚乙烯醇为膜材料，戊二醛为交联剂，通过（1）超临界CO₂流体作为非溶剂，采用相分离法使聚乙烯醇溶液成膜；（2）超临界CO₂流体作为物理发泡剂，通过发泡对聚乙烯醇薄膜进行致孔。探讨了超临界CO₂流体压力、温度、聚合物在CO₂流体中的保留时间、PVA浓度、交联剂含量、交联温度及交联时间对膜分离性能的影响。利用PEG标准分子量物质，系统分析了分离膜的孔径及孔径分布情况，并通过扫描电镜对纳滤膜的形貌结构进行表征、通过傅立叶红外光谱和X射线衍射仪对分离膜的内部结构进行了分析。对所制备PVA纳滤膜的热稳定性、耐酸碱性、耐溶剂性、溶胀性能及机械性能进行了研究，并对发酵液中红霉素的分离过程进行了研究，讨论了膜浸泡时间、操作压力、红霉素浓度等因素对分离过程的影响，取得了具有一定科学价值的研究结果。 研究表明，采用超临界CO₂流体作为致孔剂制备的PVA纳滤膜具有孔隙率高、孔径均匀的特点，分离性能优良，选择性好，并且超临界CO₂流体对PVA的塑化作用在一定程度上改善了PVA纳滤膜的耐酸碱性能。超临界CO₂流体作为物理发泡剂制备的PVA纳滤膜对红霉素的三次截留率达到93.4％，红霉素溶液的膜通量稳定在44.3L·h^-1·m^-2左右。 本论文通过超临界CO₂致孔技术，解决了纳滤膜制备中致孔剂残留、孔隙率小及孔结构不均匀等问题，并且通过超临界CO₂流体的增塑作用也大大改善了聚乙烯醇的性能。更多还原

【Abstract】 The technique of separating by membranes is a new effective, forehanded method, which have been widely used and developed. But the traditional method always introduces troubles in preparation. Such as solvent remaining, low rate of pore, et al. To solve these problems, we did some research in preparing membranes using supercritical CO₂ （SC-CO₂） fluid as a pore opener, and discussed the application in separating erythromycin.Using PVA as main materials, glutaraldehyde as a cross-link agent, to prepare PVA nanofiltration（NF） membranes through two kinds of process: （1） Using SC-CO₂ as a non-solvent to induce the phase separating in polymer solution; （2） Using SC-CO₂ as a foamer make pores in the dry polymer. The role played by PVA concentration, cross-linking conditions in the formation of NF membranes is investigated. The structure and separation performance of the NF membranes are researched systematically. Water flux, erythromycin retention and flux are investigated by Qudric Dynamic Instrument. Mesh size is measured by rentention of PEG that has different molecular weights. Microstructure of NF membranes is characterized by FT-IR, DSC, SEM and X ray diffraction. And the heat resistance, acid-base resistance, solvent resistance, swelling and mechanical properties of the NF membranes are investigated. Then the effect on filtration and purification of the erythromycin in different operation conditions is discussed.The result showed that the NF membranes which prepared using SC-CO₂ have a outstanding properties. The ternary cycle erythromycin retention and flux of NF membranes are 93.4% and 44.3 L·h^-1·m^-2 respectively. As a conclusion, the NF membranes have a prospected application in extracting erythromycin.By doing the research, the problems in preparing by traditional method have been solved effectively. And also, the properties of PVA membranes have been improved through plasticized by SC-CO₂.更多还原