改性离子交换膜抗污染性能研究进展

介绍了离子交换膜污染的原因和分类,根据对离子交换膜的不同要求,从3个方面详细阐述了提高离子交换膜抗污染性能的改性方向,指出探寻新的改性方法、开发新型亲水性膜材料是将来提高膜抗污染性能的主要途径。     

阴离子交换膜改性及抗污染性能研究进展

电渗析技术应用于工业废水脱盐时,废水中有机物及其它杂质组分等会造成膜污染,进而影响脱盐性能。电渗析膜污染防治对促进电渗析在工业废水处理中的应用有重要意义。相比于阳离子交换膜,阴离子交换膜更易形成有机污染,且更严重。阴离子交换膜污染主要由腐殖酸、牛血清蛋白、阴离子表面活性剂等有机物造成,污染过程主要受静电作用、亲和作用和几何因素的影响。膜改性提高阴离子交换膜的抗污染性能是电渗析膜污染防治的有效方法,目前已有许多有关膜改性提高阴离子交换膜抗污染性能的报道。膜改性方法主要有化学改性法、等离子体改性法、表面涂覆改性法、电沉积改性法、自聚合改性法及改进基膜结构法等。本工作对阴离子交换膜改性及抗污染性能的研究进展进行了综述,对不同改性方法的优缺点进行了分析和评价。这些改性方法能提高阴膜表面的负电荷密度和亲水性、降低膜表面粗糙度和基膜含水率等,因此可以改善阴离子交换膜的抗污染性能。然而,目前研究获得的改性阴离子交换膜仍存在修饰层不稳定、抗污染性能不理想和性能测试不系统等缺点,需进一步优化改性方法、改性工艺、组分修饰及性能测试等,以获得抗污染性能稳定且效果良好的改性阴离子交换膜。     

膜材料与生物分子相互作用的分子模拟

以生物分子的膜过滤过程为应用背景,采用分子模拟方法考察不同结构的单体分子对膜表面电位、膜与生物分子相互作用能的影响,以此为基础选择适宜的单体分子进行膜改性以降低因吸附生物分子而导致的膜污染.以氨基酸和二肽为例,采用Hyperchem软件计算考察了丙烯酸、季铵盐及它们的衍生物分子进行膜改性时的效果及其用于生物分子膜过滤时的适宜操作条件.模拟计算结果与实验结果吻合,有关相互作用能的计算结果也与前期实验结果相符.本研究显示出分子模拟技术在分离材料设计和分离过程优化方面所具有的良好应用前景.     

PVDF膜的亲水改性及其抗污染性能的研究新进展

PVDF膜由于其较强的疏水性能,在水处理应用中需要较强的驱动力,使得运行费用增加;同时膜的疏水性也会导致膜污染、膜堵塞,从而造成膜水通量的降低。因此,针对此问题,提出了PVDF膜的改性,通过对PVDF膜进行改性来提高它的亲水性能从而改善膜的性能。介绍了近年来PVDF膜亲水改性的研究新进展,PVDF膜的改性主要有表面改性和共混改性,表面改性主要有表面接枝与表面涂覆,共混改性主要的共混物质有亲水聚合物、无机纳米粒子以及碳基纳米材料等。研究发现,通过改性后的PVDF膜亲水性能、抗污染性能以及膜的机械性能都有所提高。这为解决PVDF膜的污染问题提供了一种实际可行的方法,并通过提高其亲水性而降低了运行成本。     

PVDF膜的亲水改性及其抗污染性能的研究新进展

PVDF膜由于其较强的疏水性能,在水处理应用中需要较强的驱动力,使得运行费用增加;同时膜的疏水性也会导致膜污染、膜堵塞,从而造成膜水通量的降低。因此,针对此问题,提出了PVDF膜的改性,通过对PVDF膜进行改性来提高它的亲水性能从而改善膜的性能。介绍了近年来PVDF膜亲水改性的研究新进展,PVDF膜的改性主要有表面改性和共混改性,表面改性主要有表面接枝与表面涂覆,共混改性主要的共混物质有亲水聚合物、无机纳米粒子以及碳基纳米材料等。研究发现,通过改性后的PVDF膜亲水性能、抗污染性能以及膜的机械性能都有所提高。这为解决PVDF膜的污染问题提供了一种实际可行的方法,并通过提高其亲水性而降低了运行成本。     

高分子多孔膜的表面改性与抗污染研究

采用羟基化预处理、铈盐引发和碱化预处理、Fe2 /H2O2引发两种引发体系,对聚砜(PS)膜和聚丙烯腈(PAN)膜进行表面接枝丙烯酰胺的改性,研究预处理和表面接枝改性对膜污染的影响。采用红外光谱和X光电子能谱对羟基化和接枝改性的膜表面进行表征。研究表明,表面预处理和接枝后,PS膜和PAN膜的水通量均有所下降,但提高了抗牛血清蛋白膜污染能力。     

溶剂改性聚酰胺膜的研究

实验选用聚酰胺(PA)的良溶剂醋酸作为PA膜的改性剂。改性膜对不同醇的溶胀率是随着醇中碳原子数的增加而增加。溶剂改性条件(改性时间、改性剂浓度)对改性膜的吸着性能有明显影响。随着改性时间的延长,改性膜对水的溶胀率都呈下降趋势,而对异丙醇(IPA的溶胀率基本上是先增大后减小。随着改性剂浓度的增大,改性膜对水和IPA的溶胀率都是先上升后下降,而且当醋酸浓度为6％～8％时,都达到最大值。红外光谱分析表明,醋酸改性对PA的化学结构并没有产生影响,吸着性能的变化主要来自于改性过程PA膜物理结构的变化。     

高分子分离膜材料亲水改性及对膜性能的影响

介绍了高分子分离膜材料的亲水改性中常用的化学改性和物理改性方法。化学改性可以通过膜材料化学改性和膜表面化学改性来实现 ;物理改性即高分子膜材料的物理共混也可以改善膜材料的亲水性能。同时介绍了膜材料共混改性对膜性能的影响。     

两性离子改性膜及其抗污染性能研究进展

膜的蛋白污染限制了膜的应用范围,由于两性离子具有稳定的抗蛋白质污染性能,两性离子材料已被广泛用于提高膜的抗污染性能研究中。"接枝聚合"是一种在膜表面引发接枝单体的技术。它是提高膜抗污染性能的一种简单、有用且通用的改性方法。综述了两性离子改性膜及其抗污染性能的研究进展。     

功能性中间层对聚酰胺膜水处理性能影响

含聚酰胺层（PA）的复合膜自被发明以来,就广泛应用于纳滤（NF）、反渗透（RO）、正渗透（FO）等水处理领域。但是,聚酰胺膜的渗透性和选择性的相互制约使得对其的研究亟待产生新的突破。近年来,一种位于基膜和选择层之间的中间层成为膜制备研究的热点。这种中间层会影响聚酰胺层的形貌以及界面聚合过程,因而较先前的聚酰胺膜及纳米材料复合膜在通量及截留率方面均有一定提高,是解决目前聚酰胺膜渗透性和选择性矛盾的重要途径。综述了近年来有关中间层对聚酰胺膜水处理性能的影响和机理,介绍了基于有机涂层、纳米材料及二者结合的不同类型中间层的结构和性能,以及以此制备的聚酰胺膜的性能变化,为制备高性能的聚酰胺膜提供依据。     

Improving the antifouling properties of ceramic membranes via chemical grafting of organosilanes

For enhanced antifouling surface properties, the alumina membranes were modified through a simple silanization process. Three organosilanes presenting neutral, positive, and negative charges were allowed to graft onto alumina membranes. A small decrease in the pore size and the successful chemical binding of organosilanes were confirmed, respectively. The membrane filtration test using humic acid (HA) was conducted to evaluate the effect of surface charges on fouling resistance. The neutral and negatively charged membranes achieved remarkable flux behaviour due to no charge interaction and electrostatic repulsion force, respectively. Especially, the negatively charged membranes presented the lowest flux decline, the highest flux recovery, and the lowest membrane fouling.     

Preparation and characterization of polyamide nanofiltration composite membranes with TiO2 layers chemically connected to the membrane surface

A polyamide (PA) nanofiltration (NF) composite membrane with TiO₂ layers was designed and prepared, in which the TiO₂ layers were chemically linked to the crosslinked polyamide layers of the membrane. In this study, TiO₂, one of the well known photo‐catalysts effectively degrading organics with UV light, was introduced to the PA NF membrane by using 3‐aminopropyltrimethoxysilane (APTMOS), titanium (IV) isopropoxide (TIP) to improve its antifouling property. In particular, for this membrane, SiO₂ layers were formed between the TiO₂ layer and the crosslinked polyamide layer of the membrane to protect the organic parts of the membrane from the TiO₂ catalyzed UV degradation. The prepared membrane with TiO₂ layers was then characterized using several analytical methods: scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), x‐ray diffraction (XRD) and permeation tests. It was found that the prepared membrane was stable; especially the TiO₂ layer of the membrane was found to be stable after several times of use for permeation test. The membrane showed a typical NF property, despite of the presence of the TiO₂ layer. From long time tests with or without UV light, it was found that there was good antifouling effect on the membrane by the TiO₂ layer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

聚偏氟乙烯超滤膜亲水改性研究进展

膜污染会缩短超滤膜的使用寿命,增加由于水力清洗、化学清洗以及膜组件更换而产生的费用。为减少运行成本,有必要对膜污染加以控制。膜污染与原水中污染物的性质和膜本身的性质密切相关。亲水性膜具有水通量高、抗污染性能好的特点,因而提高超滤膜的亲水性是提高膜的水通量和控制膜污染的重要方法之一。简要介绍了具有良好化学稳定性、耐辐射性、耐热性的聚偏氟乙烯膜的表面亲水改性和共混亲水改性的研究进展,指出通过不同的改性方式,聚偏氟乙烯膜都能够实现亲水性的增强。     

亲水改性PVDF膜材料及其膜生物反应器应用

膜生物反应器（MBR）技术中最常用的膜材料是聚偏氟乙烯（PVDF）,然而由于PVDF膜的疏水性,使其在用于MBR的运行过程中存在易污染、通量低等缺陷,因此对PVDF膜材料进行亲水改性是近年来国内外研究的热点。本文首先介绍了PVDF膜材料典型的表面涂覆改性和表面化学接枝改性这两种亲水改性方法,然后概述了随着纳米科学技术的兴起,采用无机纳米材料如碳材料氧化石墨烯（GO）、无机抑菌材料纳米银粒子及二氧化钛纳米颗粒等进行功能化复合制备PVDF膜材料等亲水改性方法。研究进展表明,新型亲水改性PVDF膜材料不仅在MBR污/废水处理中优势明显,而且在可再生生物能源生产等可持续发展领域极具潜力。     

The chlorination and chlorine resistance modification of composite polyamide membrane

Membrane‐based separation technology is one of the most active separation technologies being employed in water treatment. Polyamides (PA) are widely used membrane materials because they exhibit excellent performance, such as high flux with high salt rejection, and enhanced stability against wide range of pH and temperature. Unfortunately, PA membranes exhibit extremely poor resistance to chlorine leading to increased operation costs and decreased membrane lifetime. In this study, we find new ways for prolonging membrane lifetime and reducing the operating costs by investigating the chlorination and modification of PA membranes. Varying concentrations of hypochlorite were used to chlorinate a commercial reverse osmosis membrane (BW‐30, DOW). The results showed that short‐time exposure to high concentrations of hypochlorite could cause more serious problems to membranes than long‐time exposure to low concentrations under the similar total exposure. The performance of the chlorinated membranes was recovered to some extent after treatment with NaOH solution (pH 10), indicating that the alkali treatment could initiate the reversible regeneration of chlorinated membranes. Furthermore, an industrial grade epoxy resin was used to modify the membranes to enhance the chlorine resistance via the reaction between the amide nitrogen and epoxy bond. The successful modifications were confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. Moreover, the chlorination tests showed that the modifications performed in these experiments enhanced the chlorine resistance of the membranes, especially for the membranes exposed to low concentration of chlorine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41584.     

聚酰胺技术的发展现状及改性的主要方法

简述了改性聚酰胺（PA）的发展历史、研究现状和主要用途，并着重介绍了最近令人关注的非反应性、反应性增容PA合金的方法，研究动态及纳米技术在改性PA中的应用。     

Blends of thermoplastic polyurethanes and polyamide 12: Structure,molecular interactions,relaxation, and mechanical properties

Studies were done to understand the effects of polyamide 12 (PA 12) incorporation on microphase separation (microsegregation) in thermoplastic polyurethanes (TPU) based on oligoether (polytetramethylene oxide, molecular weight, 1000) and oligoester (polyethylene butylene glycol adipate, molecular weight, 2000), and relaxation transitions, compatibility, and molecular interaction energy in polymer blends. It was learned that the addition of PA 12 caused partial degradation of the domain structure in the oligoester‐containing polyurethane, whereas interaction of hard blocks in the oligoether‐containing polyurethane increased. Analyzing compatibility and interphase interactions in blends is possible in the frame of the quantum theory of relaxation processes. Also, interferences of the components on characteristic temperatures of relaxation transitions were studied. Partial compatibility was detected between PA 12 and the soft block of oligoether‐based TPU over the whole range of components concentrations tested. For oligoester‐based TPU, partial compatibility was observed only at low polyamide concentrations (up to 20 wt %). Effects of a polyurethane phase on PA 12 crystallization in the blends along with the pattern of concentration—mechanical properties dependencies are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1054–1070, 1999     

单体对分子印迹聚合物分子识别能力的影响：量子化学计算与实验研究

采用密度泛函方法计算功能单体与印迹分子的结合能,以与目标分子结合能最大的单体分子来合成分子印迹聚合物.为此,以茶碱为印迹分子,氯仿为溶剂,首先计算了茶碱与甲基丙烯酸、丙烯酰胺和三氟甲基丙烯酸的结合能,其强度顺序为：三氟甲基丙烯酸 > 甲基丙烯酸 > 丙烯酰胺.然后以茶碱为印迹分子、氯仿为溶剂、二甲基丙烯酸乙二醇酯为交联剂,分别采用上述3种单体合成分子印迹聚合物并测定了其分子识别能力,实验结果和量子化学计算结果具有一致性.最后,采用1H NMR考察了茶碱和上述3种单体之间的氢键作用,揭示出二者相互作用的内在机制.研究结果表明量子计算方法可以应用于合成分子印迹聚合物时单体的选择.     

Epitaxy of folds in polyethylene crystals: molecular mechanics investigation

In the prevailing thermodynamics associated with Gibbsian surface physics of a century ago, the surface of a crystal has an associated surface energy and surface stress that influences properties and morphology. This work uses molecular mechanics to investigate the surface energy and epitaxial packing of chain folds on the surfaces of adjacent crystals. It is shown that there are lower energy juxtapositions of the crystals resulting from energetically favorable epitaxial arrangements. These lower the excess surface energy with respect to the melt, but do not completely eliminate the discrepancy between the values of the surface energy from computational results and analysis of experimental data. The epitaxial arrangements are consistent with the experimentally observed rotational displacement of successive layers in multi-layer polyethylene crystals. Thus, they might influence the rotation of the successive layers resulting from screw dislocations.