聚酰胺正渗透膜的制备及应用研究

发布时间：2018-04-21 05:00

本文选题：正渗透 + 复合支撑层　；参考：《河南师范大学》2017年硕士论文

【摘要】：清洁的水资源短缺已经成为全球最大危机之一,因此洁净水的生产和再生成为主要的关注热点。在众多处理技术当中,正渗透以其低能耗,膜污染较轻和环境友好型等特点,在海水淡化、污水处理、盐差发电等领域受到越来越多的关注。然而,在正渗透运行过程中存在的严重的浓差极化问题,这严重影响了正渗透膜的分离效率。理想正渗透膜应具有高的水通量、低的盐通量和良好的机械强度从而能够保证膜长期稳定的运行。因此,本文从研制新型支撑层和优化支撑层结构入手。通过优化正渗透膜制备工艺,在保证高截盐率和水通量的前提下,提高正渗透膜的机械强度,从而制备出性能优良的两种正渗透膜。并对所制备的正渗透膜进行浓缩丙烯酰胺溶液的应用,重点考察正渗透膜在长期运行条件下浓缩效率和膜性能的变化。众所周知,静电纺丝纳米纤维膜具有特殊的三维连通孔结构、低的膜孔弯曲度和高的孔隙率等优点,为开发高性能的正渗透膜提供了可能。然而,静电纺丝纳米纤维膜作为支撑层仍存在机械性能差等问题,这严重影响了制备的静电纺丝正渗透膜的应用前景。因此,本文以高强度、大孔PET无纺布为底层,采用聚对苯二甲酸乙二醇酯(PET)为材料进行静电纺丝,通过对支撑层进行热压处理,制备静电纺丝复合支撑层。并以间苯二胺(MPD)和均苯三甲酰氯(TMC)为单体,采用界面聚合方法制备了新型高强度PET复合正渗透膜。实验研究了纺丝液浓度、纺丝电压、接收距离和热压处理对复合支撑层结构和机械性能的影响。实验发现,在最佳条件下制备出的复合支撑层的表面的接触角为121°,拉伸强度为11.4 MPa,相比于传统的静电纺丝膜,复合支撑层的拉伸强度得到了大幅的提升。通过对正渗透膜性能的测试发现,采用1mol/L NaCl溶液为汲取液,PRO模式下复合FO膜的水通量达到25.8 LMH,反向盐通量为4.5 gMH。在相转化制膜工艺中,采用聚砜(PSF)为原材料来制备聚砜正渗透膜。通过优化聚砜铸膜液浓度和界面聚合条件来考察对正渗透膜性能的影响。并采用电子扫描显微镜、表面接触角测试仪、XPS测试等技术手段对所制备的聚砜正渗透膜结构和性能进行表征。通过优化实验条件,当聚砜浓度在12 wt%,MPD为3.4 wt%,TMC为0.15wt%时,反应时间为60 S条件下,制备出来的正渗透膜性能最佳。在PRO模式下,1mol/L NaCl溶液为汲取液,正渗透膜的纯水通量高达42.3 LMH,远高于目前HTI商业化的FO膜,为今后正渗透膜的制备提供了研究基础。最后,本文采用聚砜正渗透膜对模拟工业生产的丙烯酰胺溶液进行浓缩实验。并采用NaCl和MgCl_2溶液作为汲取液,通过改变汲取液浓度、错流流速和活性层不同取向等条件来考察对浓缩效率的影响。通过实验发现,当采用5 mol/L的MgCl_2溶液作为汲取液时,实验运行20 h后,丙烯酰胺浓度可以从20%浓缩到40%,达到工业产品的生产要求。介于正渗透技术具有低能耗,低膜污染等特点在工业应用领域展现出巨大的优势。因此本研究为今后开发和优化丙烯酰胺浓缩工艺具有重要意义。
[Abstract]:The shortage of clean water has become one of the biggest crises in the world, so the production and regeneration of clean water has become the main focus of attention. Among the many processing technologies, the positive infiltration has attracted more and more attention in the fields of desalination, sewage treatment and salt difference power generation in the areas of low energy consumption, light membrane pollution and environment-friendly. The serious polarization problem in the positive permeation process, which seriously affects the separation efficiency of the positive permeable membrane, should have high water flux, low salt flux and good mechanical strength, thus ensuring the long-term stability of the membrane. Therefore, the new support layer and the optimal support layer are developed in this paper. By optimizing the preparation process of the positive osmosis membrane, the mechanical strength of the positive osmosis membrane is improved on the premise of high salt cutting rate and water flux, so as to prepare two kinds of positive permeable membranes with excellent performance. It is well known that the electrospun nanofiber membrane has a special three-dimensional connected pore structure, low membrane porosity and high porosity, which provides a possibility for the development of high performance osmosis membrane. However, the mechanical properties of the electrospun nanofibrous membrane still exist as a support layer, which is serious. The application prospect of the prepared electrospun positive permeable membrane was affected. Therefore, in this paper, a high strength, large pore PET non-woven fabric was used as the bottom layer, polybutylene terephthalate (PET) was used as the material to electrospun. The electrospun composite supporting layer was prepared by hot pressing on the supporting layer, and MPD (MPD) and benzyl chloride (TM) were prepared. C) a new type of high strength PET composite positive permeable membrane was prepared by interfacial polymerization. The effects of spinning solution concentration, spinning voltage, receiving distance and hot pressing on the structure and mechanical properties of the composite support layer were investigated experimentally. The experimental results showed that the contact angle of the surface of the composite support layer prepared under the optimum conditions was 121 degrees, and the tensile strength was strong. The tensile strength of the composite support layer is greatly enhanced by the degree of 11.4 MPa, compared with the traditional electrostatic spinning film. Through the test of the performance of the positive permeable membrane, the 1mol/L NaCl solution is used as the drawing fluid. The water flux of the composite FO film under the PRO mode reaches 25.8 LMH, the reverse salt is 4.5 gMH. in the phase conversion process, and the polysulfone is used. (PSF) the polysulfone positive permeation membrane was prepared for the raw materials. The effects of the concentration of polysulfone film liquid and the interfacial polymerization conditions were optimized. The structure and properties of the polysulfone positive permeable membrane were characterized by electron scanning microscope, surface contact angle tester and XPS test. The optimization experiment was carried out through the optimization experiment. Conditions, when the concentration of polysulfone is 12 wt%, MPD is 3.4 wt%, TMC is 0.15wt%, and the reaction time is 60 S, the preparation of the positive osmosis membrane is the best. In PRO mode, 1mol/L NaCl solution is a draw liquid and the pure water flux of the positive osmosis membrane is up to 42.3 LMH, which is far higher than the HTI commercialized FO membrane, which provides the research for the preparation of the positive permeable membrane in the future. In the end, the polysulfone positive permeation membrane was used to concentrate the concentration of acrylamide solution in the simulated industrial production. The effect of the concentration of drawing fluid, the flow velocity of the flow and the different orientation of the active layer on the concentration efficiency were investigated by using NaCl and MgCl_2 solution as the drawing solution. The experiment was found that the 5 mol/L Mg was used. When the Cl_2 solution is used as a drawing liquid, the concentration of acrylamide can be condensed from 20% to 40% after 20 h, which can meet the production requirements of industrial products. The characteristics of low energy consumption and low membrane fouling in the positive permeation technology show great advantages in industrial application. Therefore, this study has the advantages of developing and optimizing the process of acrylamide concentration in the future. Significance.

【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

【参考文献】