【作者】 王玥；

【导师】 史宝利；

【作者基本信息】 东北林业大学 ， 高分子化学与物理， 2013， 硕士

【摘要】 高分子膜在使用过程中,由于污水中存在的大量胶体、蛋白质和微生物会污染膜,导致膜的水通量降低和分离性能下降,进而使得膜的总体使用价格升高。在传统的水净化过程中,通常采用臭氧和次氯酸钠等物质为消毒剂,而这些消毒剂残留在水中会造成对水体的二次污染。银作为传统的抗菌材料,对液体中的微生物具有很强的杀菌和抑菌作用。本论文采用原位还原法,以聚乙烯吡咯烷酮(PVP)为分散剂,乙二醇为还原剂,在聚醚砜溶液中原位将硝酸银还原成银颗粒；同时采用浸没-沉淀相转化法,成功制备了纳米银颗粒修饰的聚醚砜平板和中空纤维两种类型的超滤膜。超滤实验结果表明,纳米银颗粒修饰后的聚醚砜平板膜和中空纤维膜的水通量和对牛血清蛋白质溶液的截留率均大于未修饰的聚醚砜膜。修饰后的聚醚砜膜抗牛血清蛋白质污染能力比未修饰的膜要强。并且修饰后的聚醚砜膜对大肠杆菌繁殖有明显的抑制作用,能够提高膜的抗生物污染能力。论文研究了凝固浴温度对平板膜的结构和性能及纳米银颗粒稳定性的影响。研究发现,随着凝固浴温度的升高,纳米银颗粒修饰后的聚醚砜膜结构中的海绵层厚度逐渐减小,指状孔结构逐渐变大。由于水通量和截留率均与膜结构有关,所以随着凝固浴温度的升高,聚醚砜和纳米银颗粒修饰的聚醚砜膜的水通量均升高但截留率下降。纳米银颗粒修饰的聚醚砜平板膜的断裂强度比未修饰的聚醚砜膜高。随着凝固浴温度的升高,膜的断裂强度下降。银流失率实验结果表明,在凝固浴温度为40℃下制备的纳米银颗粒修饰聚醚砜膜的流失率最小为18.5%；此时膜的水通量为393L·m-2·h-1,截留率为95.2%。论文还研究了PVP含量对纳米银颗粒修饰聚醚砜中空纤维膜的结构和性能及纳米银颗粒稳定性的影响。研究发现,随着PVP含量的增加,聚醚砜和纳米银颗粒修饰聚醚砜中空纤维膜的结构由典型非对称结构,即内层为指状孔、外层为海绵层的结构转变为双排指状孔对称结构。随着PVP含量的升高,中空纤维膜的水通量升高,但对牛血清蛋白质的截留率下降。当PVP含量为7.5%时,银颗粒修饰的聚醚砜中空纤维膜的抗污染能力达到最强,膜的综合性能达到最佳。此时膜中银颗粒的含量为加入量的98.7%,膜的初始水通量为183L·m-2·h-1,截留率为94.5%,断裂强度为2.87MPa。更多还原

【Abstract】 During the permeation of polymer membrane, the existence of a large sewage in waste water, such as colloids, proteins and microbes can cause membranes fouling, which lead to reductions of water flux and separation property, thereby increasing the cost of the membrane application. Customary water purification methods usually use ozone and sodium hypochlorite to sterilization. The residual disinfectants in water can cause secondary pollution. Silver as traditional anti-bacterial material, has strong abilities of sterilization and inhibition bacterial growing.In this dissertation, an in situ reduction method was used to prepare nano-silver modified polyethersulfone (PES-Ag) ultrafiltration (UF) membrane casting solution. Under the portaction of polyvinylpyrrolidone (PVP), ethylene glycol was used as reducing agent to reduce AgNO3into nano-silver particles in the PES solution. PES-Ag flat and hollow fiber UF membranes were prepared by immersion-precipitation phase inversion.UF performance experimental data showed that the water flux and bovine serum albumin (BSA) protein rerejection rate of PES-Ag UF membranes were greater than the unmodified PES membranes. Flux recovery rate experiments showed that the against BSA contamination capacity of PES-Ag membranes were stronger than original PES membranes. As the meantime, PES-Ag membrane could inhibit E. coli from growing and improve the ability of anti-biological contamination.In this work, the effect of coagulation bath temperature (CBT) on the nano-silver particles modified PES flat UF membranes structures and separation performances, and the stability of the nano-silver particles were researched. With the increase of CBT, the thickness of sponge-like sublayer of PES-Ag flat membranes decreased and the size of finger-like pores enlarged. The water flux and rejection rate largely depended on the morphology of the membranes. Thus, as the CBT increasing, the water flux of PES-Ag flat membranes increased while the rejection rate decreased. The tensile strength of PES and PES-Ag flat membranes reduced with the increase of CBT. The results of silver stability revealed that PES-Ag flat membrane prepared in40℃coagulation bath showed a low nano-silver loss rate that was only18.5%; the water flux and rejection rate were393L·m-2·h-1and95.2%, respectively.Effect of PVP content on PES-Ag hollow fiber structures and performances, and the stability of nano-silver particles were also researched in this work. With the increase of PVP content, the structures of PES and PES-Ag hollow fiber changed from asymmetric structure with finger-like sublayer and sponge-like support layer into double row finger-like symmetrical structure. With the raise of PVP content, the water flux increased, while the rejection rate decreasd. When the PVP content was7.5%, antifouling ability of PES-Ag hollow fiber achieved the strongest, at this time the overall performances of the PES-Ag hollow fiber were best. The silver content of the PES-Ag hollow fiber was98.7%of added amount; the water flux, rejection rate and breaking strength were183L·m-2·h-1,94.5%and2.87MPa, respectively.更多还原