【作者】 郑凤；

【导师】 黄征青；

【作者基本信息】 湖北工业大学 ， 化学工艺， 2010， 硕士

【摘要】 聚偏氟乙烯(PVDF)有良好的化学稳定性、耐温性等优势,但强疏水性限制了PVDF超滤膜的应用,因此近年来制备有机-无机杂化膜的研究受到大量关注。目前,以PVDF为基材、采用磁性四氧化三铁(Fe304)作为无机填料制备有机-无机杂化超滤膜的研究较尚未见报道；若在制膜过程中外加磁场将改变磁性Fe304粒子的排列,并可能对膜的结构和性能产生影响,目前相关研究较少。本文首先采用浸没沉淀相转化法制备PVDF-Fe3O4杂化超滤膜(称为未磁化膜),通过超滤实验评价膜的通量、截留率、耐污染性、强度等性能,并用扫描电镜(SEM)观察膜的断面结构,研究Fe304含量和PVDF浓度对未磁化膜的影响。然后在凝胶浴外使用水平磁场,在其他条件完全相同的条件下制备PVDF-Fe3O4杂化超滤膜(称为磁化膜),并研究Fe304含量和PVDF浓度对磁化膜的影响。最后比较磁化膜与未磁化膜性能与结构的差别,并测试磁化膜与未磁化膜的接触角、红外光谱和动态力学实验(DMA),进一步探讨磁场对制备PVDF-Fe3O4杂化超滤膜的影响。研究结果表明,在无磁场条件下制膜,当Fe304含量低于65wt%时,膜通量随Fe304含量缓慢上升,当Fe304含量在65wt%～80wt%之间时,纯水通量迅速上升；随着Fe304含量的增加,截留率表现为先缓慢上升,当填料量为65wt%后基本稳定；填料含量为70wt%～75wt%的未磁化膜强度较好；从未磁化膜的断面SEM照片可知,Fe304粒子对皮层影响不大,但能使支撑层得到更疏松的结构。PVDF浓度为14.6wt%,Fe3O4含量为70wt%时,未磁化膜综合性能较好。磁化膜得到了与未磁化膜相似的规律,但从Fe304含量为60wt%磁化膜断面SEM照片可知,磁场改变了Fe304粒子的排列,增加了支撑层中大孔和微孔的数量,并能大幅加强支撑层在平行于膜表面方向上的贯通性；当PVDF浓度为14.6wt%,Fe3O4含量为70wt%时,磁化膜综合性能较好。比较有／无磁场下制备的磁化膜与未磁化膜结构和性能的差异可知,磁场能增加膜的纯水通量、提高膜的亲水性,但对截留率几乎没有影响。更多还原

【Abstract】 Polyvinylidene fluoride (PVDF) with excellent chemical stability and appropriate temeperature tolerance is one of materials applied to prepare ultrafiltration (UF) membranes, but its hydrophobic property limits the application of PVDF UF membrane due to serious membrane fouling. In order to improve hydropholic property, some inorganic filler can be added into the casting solution to prepare organic-inorganic hybrid PVDF ultrafiltration membranes. Fe3O4 is a kind of hydrophilic filler with magnetic property. An external magnetic field may change the arrangement of Fe3O4 particles in the membranes and influence the structures and the properties of membranes. However, PVDF-Fe3O4 UF hybrid membranes were not reported in the literatures.PVDF-Fe3O4 hybrid membranes with different Fe3O4 content and PVDF concentration were prepared by a wet phase inversion process. The membranes were investigated by ultrafiltration experiments for water flux, rejection, anti-fouling ability and anti-pressure strength. The cross-sectional structures were examined by a scanning electron microscopy (SEM). PVDF-Fe3O4 hybrid membranes with different Fe3O4 content and PVDF concentration were also prepared in an external magnetic field by a wet phase inversion process. In addition, a comparison between membranes prepared in no external magnetic field and membranes prepared in an external magnetic field was given by some further experimental data from contact angle, FTIR and DMA.The results shows that the water fluxes of membranes prepared in no external magnetic field slowly increase with Fe3O4 content (less than 65wt%), and then abruptly increase with Fe3O4 content (changed from 65wt% to 80wt%); The rejection of membranes slowly first rises with Fe3O4 content, and then keep stable when Fe3O4 content reaches 65wt%. Membranes with 70wt%～75wt% Fe3O4 filler have better intensity. The membrane with 70wt% Fe3O4 and 14.6wt% PVDF has a best composite performance.The performances of membranes prepared in an external magnetic field have the same change trends as those of membranes prepared in no external magnetic field. However, the obvious change of micro-structures from the cross sections can be observed in the those membranes with 60wt% Fe3O4 above the macro pores in the sublayer become parellel to the membrane surface along the external magnetic field. The membrane with 70wt% Fe3O4 and 14.6wt% PVDF has also a best composite performance.An external magnetic field can improve the water flux and the hydrophilic property of membranes, but has no obvious effect on the rejection of membranes.更多还原