基于配位作用的层层自组装正渗透膜制备与应用

发布时间：2018-03-29 15:36

本文选题：层层自组装　切入点：配位作用　出处：《中国海洋大学》2015年硕士论文

【摘要】：与压力驱动的膜分离技术相比,正渗透(FO)技术不需要外加压力作为分离驱动力,并具备能耗低、水回收率高、污染倾向低的特点。FO技术不仅在水处理领域获得了重视与关注,也在其它应用方向上具有很大的发展潜力。层层自组装(LBL)技术是一种自上世纪90年代快速发展起来的表面修饰方法,是利用带电基膜在带相反电荷的聚电解质溶液中交替沉积制备多层膜的制备技术。配位作用是一种相对稳定的LBL技术推动力,常用于纳滤工艺中。然而,即使近年来LBL技术开始用于FO膜的制备,但尚未出现配位作用参与沉积过程制备的LBL-FO膜的相关报道。本文基于金属离子配位作用,采用聚乙烯亚胺(PEI)和聚苯乙烯磺酸钠(PSS)两种聚电解质,以改性的聚丙烯腈(PAN)为基膜制备LBL-FO膜,通过扫描电镜(SEM)、原子力显微镜(AFM)、接触角、X射线光电子能谱(XPS)、红外光谱(FTIR)等表征方法分析自组装机理,观察膜的表面形貌,并对膜的性能进行考察。经过研究,当使用0.50M的MgCl2溶液作为汲取液、去离子水作为进料液时,FO模式下以配位作用作为成膜推动力的LBL(PEI/PSS(Cu)1/2)3FO膜的水通量可以达到约16LMH,反向盐通量低于1.5gMH。得到的LBL (PEI/PSS(Cu)1/2)3FO膜的最佳制备条件为：聚电解质单层沉积时间为10min,支撑电解质NaCl浓度为0.50M,配位剂CuCl2浓度为0.20M,聚电解质PEI和PSS浓度均为1.00g/L,PEI溶液pH值为9。FO模式下LBL (PEI/PSS(Cu)1/2)4 FO膜的水通量可达到约11LMH,反向盐通量低于1.3gMH。经过GA交联,FO模式下LBL(PEI/PSS(Cu)1/2)3x FO膜的水通量可达到约12LMH,反向盐通量仅为1.25gMH, PRO模式下水通量可达到约14LMH,反向盐通量低于6gMH。其中,最佳的GA交联剂浓度与交联时间分别为1.0%和30min。LBL (PEI/PSS(Cu)1/2)3 FO膜与LBL(PEI/PSS(Cu)1/2)3x FO膜对一价离子的截留能力均较差。SEM照片表明,LBL (PEI/PSS(Cu)1/2)3FO膜的表面形貌良好,不存在明显膜孔,致密层的致密性较高。AFM照片表明,相比于改性基膜,LBL(PEI/PSS(Cu)1/2)3 FO膜表面粗糙度提升,比表面积增加,有利于水分子的扩散。LBL(PEI/PSS(Cu)1/2)3 FO膜的表面接触角较小,膜具有较好的亲水性。由FTIR和XPS结果表明,PSS(Cu)1/2与仲胺基团间优先发生了配位作用,推动自组装过程的进行。LBL (PEI/PSS(Cu)1/2)3 FO膜在海水淡化中的应用存在一定限制,但是通过增加自组装膜层数或采用GA交联后处理,可以提高该膜在海水淡化应用中的性能。利用自组装膜的特性,LBL (PEI/PSS(Cu)1/2)3 FO膜在低聚糖溶液浓缩脱盐应用中具有较高的实际应用价值。
[Abstract]:Compared with the membrane separation technology driven by pressure, the forward osmosis FOO technology does not need external pressure as the separation driving force, and has the characteristics of low energy consumption, high water recovery and low pollution tendency. FO technology has not only been paid attention to and paid attention to in the field of water treatment. The layer by layer self-assembly (LBL) technique is a surface modification method developed rapidly since the 1990s. The preparation of multilayer films by alternating deposition of charged base membranes in polyelectrolyte solutions with opposite charges. Coordination is a relatively stable driving force of LBL technology and is often used in nanofiltration. Although LBL technology has been applied to the preparation of FO films in recent years, there have not been reports of coordination roles in the preparation of LBL-FO films, which are involved in the deposition process. This paper is based on the coordination of metal ions in the preparation of FO films. Poly (ethylene imine) (PEI) and polystyrene sulfonate (PSS) polyelectrolyte were used to prepare LBL-FO membrane with modified polyacrylonitrile (pan) as the base membrane. By means of scanning electron microscope (SEM), atomic force microscope (AFM), contact angle X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FTIR) and other characterization methods, the self-assembly mechanism was analyzed, the surface morphology of the film was observed, and the properties of the film were investigated. When a 0.50m MgCl2 solution is used as the extraction solution, When deionized water is used as feed solution, the water flux of LBL(PEI/PSS(Cu)1/2)3FO membrane with coordination as the driving force of film-forming can reach about 16LMH, and the reverse salt flux is lower than 1.5gMH. the optimum preparation conditions of LBL / PEI / PSS / Cu1 / 2FO membrane are as follows: polyelectrolyte monolayer deposition. When the time is 10 min, the concentration of NaCl is 0.50 M, the concentration of coordination agent CuCl2 is 0.20 M, the concentration of polyelectrolyte PEI and PSS is 1.00 g / L PEI solution pH value is 9.FO, the water flux of LBL / PEI / PSS / 2 / 2FO membrane can reach about 11LMHand the reverse salt flux is less than 1.3gMH. after GA crosslinking, the water flux of the membrane is about 11LMHand the reverse salt flux is less than 1.3gMH. the water flux of the membrane is about 11LMHand the reverse salt flux is less than 1.3gMH. The water flux of LBL(PEI/PSS(Cu)1/2)3x FO membrane is about 12 LMH, the reverse salt flux is only 1.25 g MH, the water flux of PRO model is about 14 LMH, and the reverse salt flux is less than 6 g MH. The optimum crosslinking agent concentration and crosslinking time were 1.0% and 1.0%, respectively, and the retention ability of 30min.LBL / PEI / PSS / Cu1 / 2FO and LBL(PEI/PSS(Cu)1/2)3x FO films to monovalent ions were both poor. The results showed that the surface morphology of LBL / PEI / PSS / PSSCu / 2 / 2FO films was good, and there was no obvious pore in the films. Compared with the modified base film, the surface roughness and specific surface area of the modified LBLPEI / PSSI / PSSI / Cu1 / 2FO film increased, which was beneficial to the diffusion of water molecules. The surface contact angle of the film was smaller than that of the modified LBLPEI / PSSPSSCu / 2FO film. The results of FTIR and XPS show that the coordination between the 1 / 2 and secondary amine groups preferentially occurs, which promotes the self-assembly process. The application of the membrane in seawater desalination is limited to a certain extent. But by increasing the number of self-assembled layers or by using GA crosslinking, It can improve the performance of the membrane in seawater desalination application. The LBL / PEI / PSSI / PSSN / Cu1 / 2 / 2FO membrane has high practical value in the application of concentrated desalination of oligosaccharide solution.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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