聚砜反渗透基膜的制备及其性能的研究

发布时间：2018-07-01 11:54

本文选题：聚砜 + 聚乙二醇　；参考：《贵州大学》2015年硕士论文

【摘要】：本文以聚砜(PSF)为原材料,N,N-二甲基乙酰胺(DMAc)为溶剂,不同分子量的聚乙二醇(PEG)、吐温80(Tween80)、磺化聚砜(SPSF)为添加剂,通过浸没沉淀相转化法制备了PSF平板膜和PSF中空纤维膜。研究了PSF含量、PEG分子量及含量对PSF平板膜和PSF中空纤维膜结构与性能的影响;考察了不同种类的亲水性添加剂Tween 80和SPSF对PSF中空纤维膜的结构与性能的影响;同时还探讨了制膜工艺如空气间隙、凝固浴温度及组成以及芯液组成等对PSF中空纤维膜结构和性能的影响。用自制的膜通量测试装置测定了PSF中空纤维膜的纯水通量和截留率,用扫描电境观察了膜的断面结构和表面形态,采用重量法和滤速法测定了PSF中空纤维膜的孔隙率和平均孔径,得到本研究范围内最优制膜工艺。研究结果表明,随着PEG分子量和含量以及PSF含量增加,铸膜液粘度增加,抑制了大孔结构的生成,相应的膜断面结构中指状孔的数量减少,海绵孔的区域增加。当铸膜液粘度高于8.25Pa·s时,制得的PSF膜断面结构基本为海绵状孔。相同实验条件下,PEG分子量增加,PSF中空纤维膜的平均孔径和孔隙率略有降低,纯水通量降低,截留率变化幅度不大,同时膜的拉伸强度降低;随PEG含量增加,PSF膜的纯水通量先降低后增加,BSA截留率表现出相反的趋势。当PEG/DMAc=0.8时,膜结构主要以海绵状孔为主,膜纯水通量最低,但BSA截留率高于90%;PSF含量增加,膜中大孔结构被抑制,膜的纯水通量随PSF含量增加而降低,BSA截留率则相反,当PSF含量达到20%时,膜断面结构主要以海绵状孔为主,但当PSF含量继续增加时,膜的纯水通量反而升高,BSA截留率却大幅降低。PSF含量为20%时,PSF中空纤维膜综合性能最佳。PSF中空纤维膜的纯水通量随空气间隙(即预蒸发时间)增大和凝固浴温度升高而呈上升趋势,BSA截留率则相应降低。为进一步提高PSF中空纤维膜的纯水通量,在膜中添加了亲水的Tween80和SPSF。研究结果显示,将Tween 80加入铸膜液中,PSF膜的表面接触角有所降低,亲水性有所增加,纯水通量随Tween 80的增加呈先增大后减小的趋势,截留率则呈相反的趋势。Tween 80对PSF中空纤维膜亲水性虽有一定的改善作用,但改善的程度有限,实际意义不大。SPSF使得PSF表面接触角的降低程度较高,膜的亲水性显著增加,纯水通量大幅度提高。但由于存在PSF和SPSF的相容性问题,当SPSF的含量较高时,膜的截留率降低幅度增大。综合考虑PSF中空纤维膜的纯水通量和截留率问题,SPSF含量最佳为1.5%。无论是在凝固浴还是在芯液中添加溶剂DMAc,均使得PSF中空纤维膜的平均孔径增大,孔隙率增多,外表面开孔增多,内表面孔径增大,因而PSF中空纤维膜的纯水通量随凝固浴或芯液中的DMAc含量增加而升高,BSA截留率则相应降低。
[Abstract]:In this paper, PSF flat membrane and PSF hollow fiber membrane were prepared by immersion precipitation phase transformation method with polysulfone (PSF) as raw material, N- N- dimethyl acetamide (DMAc) as solvent, polyethylene glycol (PEG) with different molecular weight, Tween80 (Tween80) and sulfonated polysulfone (SPSF) as additives. The effects of PSF content and PEG molecular weight and content on the structure and properties of PSF flat membrane and PSF hollow fiber membrane were studied, and the effects of different hydrophilic additives Tween80 and SPSF on the structure and properties of PSF hollow fiber membrane were investigated. At the same time, the effects of membrane preparation technology such as air gap, coagulation bath temperature and composition and core liquid composition on the structure and properties of PSF hollow fiber membrane were also discussed. The pure water flux and rejection rate of PSF hollow fiber membrane were measured by a self-made membrane flux test device. The cross section structure and surface morphology of PSF hollow fiber membrane were observed by scanning electroporation. The porosity and average pore size of PSF hollow fiber membrane were measured by gravimetric method and filtration rate method. The results show that with the increase of PEG molecular weight and content of PSF, the viscosity of casting solution increases, which inhibits the formation of macroporous structure, decreases the number of finger pores and increases the area of sponge pore in the corresponding membrane cross-section structure. When the viscosity of casting solution is higher than 8.25Pa / s, the section structure of PSF film is basically sponge pore. Under the same experimental conditions, the average pore size and porosity of PSF hollow fiber membrane increased with the increase of PEG molecular weight, the mean pore size and porosity of PSF hollow fiber membrane decreased slightly, the pure water flux decreased, the retention rate changed little, and the tensile strength of the membrane decreased. With the increase of PEG content, the pure water flux of PSF membrane first decreased and then increased the retention rate of BSA showed the opposite trend. When PEG / DMAcO was 0.8, the membrane structure was mainly spongy pore, the membrane pure water flux was the lowest, but the BSA rejection rate was higher than 90% PSF content, and the macropore structure was inhibited. The membrane pure water flux decreased with the increase of PSF content, but the BSA retention rate decreased with the increase of PSF content. When the content of PSF reached 20, the membrane cross-section was mainly composed of spongy pores, but when the content of PSF continued to increase, On the contrary, the pure water flux of the membrane increased, but the rejection rate of BSA decreased significantly. When the content of PSF was 20, the PSF hollow fiber membrane had the best comprehensive performance. The pure water flux of the membrane increased with the air gap (I. e., the pre-evaporation time) and the coagulation bath temperature increased. The rejection rate of BSA decreased with the increase of BSA. In order to further improve the pure water flux of PSF hollow fiber membrane, hydrophilic Tween80 and SPSF were added to the membrane. The results showed that the surface contact angle and hydrophilicity of PSF membrane were decreased, and the pure water flux increased firstly and then decreased with the increase of Tween80. Tween80 can improve the hydrophilicity of PSF hollow fiber membrane, but the degree of improvement is limited, the actual meaning is not significant. SPSF makes the surface contact angle of PSF decrease higher, and the hydrophilicity of membrane increases significantly. The pure water flux has been greatly increased. However, due to the compatibility of PSF and SPSF, when the content of SPSF is high, the decrease of membrane retention increases. Considering the pure water flux and rejection rate of PSF hollow fiber membrane, the best SPSF content is 1.5 kW. Both in coagulation bath and in core solution, the average pore size and porosity of PSF hollow fiber membrane were increased, the opening and internal surface pore size of PSF hollow fiber membrane were increased, respectively. Therefore, the PSF hollow fiber membrane's pure water flux increases with the increase of DMAc content in coagulation bath or core solution, and the increase of BSA retention rate decreases accordingly.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

【参考文献】