PEI交联的PECH/nylon复合阴离子交换膜的制备及性能研究

聚环氧氯丙烷(PECH)是一种线性高分子聚合物,具有较好的稳定性和成膜性能,且以PECH为基体制备阴离子交换膜,可避免致癌物质如氯甲醚、双氯甲醚的使用,但存在机械强度差与吸水性较大等缺点。本研究采用聚乙烯亚胺(PEI)作为交联剂,通过其与PECH发生交联反应,在其内部形成网状结构限制PECH膜在水中的过度溶胀,从而增强膜的机械强度,同时引入尼龙网布(nylon)作为支撑材料进一步提高膜的力学性能,制备了QCPECH/nylon复合阴离子交换膜。研究结果表明,制备的P1膜在电渗析应用过程中的脱盐效率(94.8%)比商业膜(Neosepta AMX)的脱盐效率(92.4%)更高,由此可见,用PEI交联的PECH/nylon复合阴离子交换膜在电渗析脱盐中具有潜在的发展前景。     

聚苯并咪唑/改性聚环氧氯丙烷阴离子交换膜的性能

通过缩聚法制备了含氟聚苯并咪唑(FPBI),以1–甲基咪唑和聚环氧氯丙烷为原料,制备了咪唑盐修饰的聚环氧氯丙烷(Im PECH),并通过溶液浇铸法制备了FPBI/Im PECH复合膜。系统地研究了复合膜中Im PECH含量的不同对复合膜的力学性能、热稳定性、离子电导率、离子交换容量(IEC)、吸水率、溶胀度等性能的影响。研究结果表明,随着Im PECH含量的增加,复合膜的吸水率、溶胀度、IEC、离子电导率逐渐增加,依然能够保持良好的力学性能和热稳定性。FPBI/Im PECH复合膜在80℃下最高电导率达到55.74 m S/cm,并展示了优异的耐碱性,该复合阴离子交换膜有望在碱性阴离子交换膜燃料电池中得到应用。     

电渗析法处理高盐度高COD废水矿化度的试验研究

运用电渗析技术,采用聚偏氟乙烯（PVDF）阳离子交换膜、纳米二氧化硅（SiO₂）/PVDF阳离子交换膜、改性SiO₂/PVDF阳离子交换膜和商品阳离子膜处理高盐度、高COD废水。研究发现,电压、流量、脱盐时间和聚丙烯酰胺的黏附量对其脱盐效果有一定的影响,并通过比较改性SiO₂/PVDF阳离子交换膜和商品阳离子膜的脱盐实验,证明改性SiO₂/PVDF阳离子交换膜脱盐能力强、抗污染程度高。     

甲基丙烯酸环氧丙脂型均相膜的合成研究

随着离子交换膜电渗析技术的发展,新型离子交换膜不断出现。近年来,国外出现了环氧树脂——多元胺类阴膜,国内最近首次报道了氯乙醇橡胶脂肪族型强碱性阴膜,这些膜均具有优良的机械和电化学性能。以往制备强碱性阴膜多是苯乙烯类型,需用剧毒物质氯甲醚作为氯甲基化试剂,对工人键康带来一定的影响。离子交换的一个重要用     

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。     

焦化生化出水电渗析脱盐研究

采用电渗析技术对焦化生化出水如曝气生物滤池出水及反渗透浓水进行脱盐,考察不同废水中的离子迁移、废水脱盐及离子交换膜污染情况。结果表明:2种焦化废水采用电渗析处理具有较好的脱盐效果,其中不同离子的迁移脱除与其浓度、离子半径等密切相关。膜电阻测试表明,不同焦化废水电渗析体系中不同离子交换膜的污染存在差别。扫描电镜和红外分析表明,曝气生物滤池出水主要由有机物造成阴离子交换膜污染,而反渗透浓水主要在电渗析浓室侧的膜表面形成颗粒状的无机污染,且阳膜浓室侧比阴膜浓室侧更显著。     

聚苯乙烯/聚偏氟乙烯阳离子交换合金膜的研制与性能

以聚偏氟乙烯为离子交换膜基体材料,将它溶解后再与苯乙烯和二乙烯苯混合,随后热引发交联共聚,得到胶状物;再经过挤出、固化、造粒、干燥、粉碎等高分子物理加工处理,得到聚苯乙烯/聚偏氟乙烯合金粉末,磺化后制备出阳离子交换粉;采用类似于异相膜生产的热压成型方法,制得具有半互穿网络结构的聚苯乙烯/聚偏氟乙烯阳离子交换合金膜。性能测试表明,膜面电阻为4.8Ω·cm2,阳离子选择透过率为96.2%,电渗析脱盐综合性能明显优于国产异相膜,与国外均相膜接近。     

光催化膜对水中腐植酸的去除及积垢机理

利用湿式相转化方法制备TiO₂/聚苯砜（polyphenylsulfone,PPSU）/聚醚亚硫胺（polyetherimide,PEI）催化膜应用于水中腐植酸（humic acid,HAs）的去除及积垢机理研究。结果表明,随着亲水性PEI比例增加,光催化膜的纯水通量和HAs的过滤通量越大,去除效率越低;且随着光照时间的延长去除效率越趋于稳定,且有回复的现象。在0.2MPa操作压力下,制备的TiO₂/PPSU/PEI （1%/50%/50%）膜具有最佳的可逆阻抗力比例（R_c/R_t=48.24%）;其渗透通量、HAs去除效率及反洗后通量分别为34.0L/（m²·h）、63.2%及22.5L/（m²·h）,具有较佳的通量及HAs去除效率。     

耐溶剂聚醚酰亚胺复合纳滤膜的制备

研究了聚醚酰亚胺基膜经乙二胺交联处理前后的耐溶剂性,并在PEI基膜上利用间苯二胺和均苯三甲酰氯进行界面聚合制备出聚酰胺/PEI复合纳滤膜。采用红外、扫描电子显微镜、X光电子能谱等对复合膜结构、耐溶剂性、分离性能进行了表征;结果表明经过乙二胺交联的PEI基膜耐溶剂性显著提高,所制备的聚酰胺/PEI复合纳滤膜对葡萄糖的截留率达到98.9%,通量达到7.8 L/(m2·h),在乙醇、丙酮、乙酸乙酯等有机溶剂中分离性能稳定。     

荷正电季铵化壳聚糖/聚醚酰亚胺复合纳滤膜的制备及性能研究

以无纺布增强具有耐溶剂、耐热特性的聚醚酰亚胺(PEI)超滤(UF)膜为支撑层,具有荷正电性和良好成膜性的2-羟丙基三甲基氯化铵壳聚糖(HACC)为功能层,制备了一种荷正电HACC/PEI复合纳滤(NF)膜。考察了聚合物浓度、反应时间、交联剂浓度及交联温度等对所制备的复合纳滤膜性能的影响,并利用扫描电镜(SEM)观察了该复合纳滤膜的表面形貌。结果表明:最佳制备条件下得到的HACC/PEI复合纳滤膜在0.3 MPa、20℃下对MgCl2具有较好的分离效果,其通量和截留率分别为10.9 L/(m2·h)和83.1%;另外,HACC/PEI复合纳滤膜呈现典型的荷正电特征,对二价无机盐具有较高的截留率。     

Anion conductive polymer nanofiber composite membrane: effects of nanofibers on polymer electrolyte characteristics

Polymer composite membranes composed of anion conductive polymer nanofiber mats and the corresponding polymer matrix were prepared and characterized for future alkaline fuel cells. In this paper, electrospinning was attempted to fabricate anion conductive nanofiber mats. The anion conductivity of the composite membrane was higher than the corresponding membrane without nanofibers under all conditions due to outstanding anion conductive characteristics of the nanofibers. In addition, because of the rigid and anisotropic structure of the nanofibers, membrane stabilities such as reductive degradation resistance and mechanical strength were very much improved. The gas permeability and excessive hydration swelling that will degrade fuel cells after long‐term operation were suppressed in the nanofiber composite membrane. These results indicated that excellent properties of the anion conductive nanofibers were demonstrated even in the composite membrane, leading to the potential application of anion conductive nanofibers in future fuel cells. © 2016 Society of Chemical Industry     

工业废水电渗析过程中膜污染研究进展

综述了工业废水电渗析体系膜污染类型、性质、影响因素等的研究进展. 无机污染主要是Ca2+, Mg2+或其他高价离子在离子膜表面或内部形成的结垢现象,原理是极化或溶液过饱和形成沉淀. 有机污染是由蛋白、腐植酸、表面活性剂及大分子有机物在离子膜表面沉积或渗透到膜内部而形成,原因主要是带负电荷的有机物与阴膜荷正电基团的静电作用及带苯环有机物与基膜的亲和作用,其次是有机物分子大小与膜的网络结构的作用. 膜污染形成及其性质与施加电流、共存组分、温度、pH值和运行时间等密切相关,可造成离子膜导电性、离子交换容量、水含量和极限电流密度等减小,且有机污染对电渗析性能的影响比无机污染更严重. 由有机物凝胶层形成的膜污染可用电渗析膜污染指数定量描述.     

Elaboration of ion‐exchange membranes with semi‐interpenetrating polymer networks containing poly(vinyl alcohol) as polymer matrix

Ion‐exchange membranes were prepared with semi‐interpenetrating networks (s‐IPNs) by mixing a film‐forming polymer, poly(vinyl alcohol) (PVA), for the crosslinked matrix and a polyelectrolyte for the specific ion‐exchange property. Poly(sodium styrenesulfonate) (PSSNa), poly(styrenesulfonic acid) (PSSH), and poly(acrylic acid) (PAA) were used as anionic polyelectrolytes. Polyethyleneimine (PEI), poly(1,1‐dimethyl‐3,5‐dimethylenepiperidinium chloride) (PDDPCl), and poly(diallyldimethylammonium chloride) (PDDMACl) were used as cationic polyelectrolytes. Membranes with PVA 60% and polyelectrolyte 40% showed the best compromise among mechanical, homogeneous, and ion‐exchange properties. Gaseous dibromoethane was used as a crosslinking agent to form the PVA network and for efficient entrapment of the polyelectrolyte in the membrane. The crosslinking time (tc) was optimized for each type of membrane and its influence was studied by thermogravimetric analysis of the sample and scanning electron microscopy observations. The best results (large ion‐exchange capacity and small swelling ratio) were obtained for PVA/PAA and PVA/PSSNa/PSSH membranes. Among anion‐exchange membranes, PVA/PEI gave the best permselectivity (low co‐ion leakage) and the highest ion‐exchange capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1572–1580, 2002; DOI 10.1002/app.10420     

氧化石墨烯/磺化聚苯并咪唑高温质子交换膜的制备和表征

通过共混法和原位聚合法成功制备氧化石墨烯（GO）/磺化聚苯并咪唑（SPBI）质子交换复合膜。用FTIR及TEM表征了复合膜的结构,并测试了复合膜的热稳定性、力学性能、尺寸稳定性、含水率、酸掺杂率、氧化稳定性及质子电导率,重点考察不同制备方法、GO的加入对GO/SPBI质子交换复合膜结构和性能的影响。实验结果表明,GO在Y-GO/SPBI-1%复合膜中呈薄片状并良好分散。添加GO后复合膜的力学性能大幅提高,拉伸强度相较于Nafion 117膜（26.65MPa）提高了2.5倍。Y-GO/SPBI-1%复合膜热稳定性稍高于G-GO/SPBI-1%复合膜。Y-GO/SPBI-1%复合膜拥有与SPBI膜相当的含水率,比G-GO/SPBI-1%复合膜的含水率提高了51.36%,表明原位聚合法制备的膜具有良好的保水能力。原位聚合法制备的复合膜具有更高的酸掺杂率和更低的酸溶胀度,提高了膜的尺寸稳定性。Y-GO/SPBI-1%质子交换复合膜在相对湿度40%、160℃下具有最高的质子电导率0.113S/cm。GO上的含氧官能团有助于复合膜中质子的跳跃,原位聚合法使GO更均匀地分散在SPBI基质中,对复合膜质子电导率的提高起到关键作用。     

Developing homogeneous ion exchange membranes derived from sulfonated polyethersulfone/N-phthaloyl-chitosan for improved hydrophilic and controllable porosity

Ion exchange membranes (IEMs) composed of sulfonated poly (ether sulfone) (SPES) and N-phthaloyl chitosan (NPHCs) were synthesized. NPHCs was employed in membrane fabrication to improve the porosity and hydrophilicity of membranes. The effect of blend ratio of sulfonation (DS) and NPHCs content on physico-chemical characteristics of home-made membranes was investigated. The morphology of prepared membranes was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and scanning electron microscopy (SEM). SEM images revealed the formation of a more porous membrane structure and smoother surface. The electrochemical and physical properties of CEMs were characterized comprising water content, contact angle, ion exchange capacity (IEC) and thermal stability. Membrane water content, surface hydrophilicity and IEC were enhanced with increase of DS and NPHCs blend ratios in casting solution. Furthermore, the diffusion coefficient was also improved slightly with increase of DS and NPHCs blend ratios in prepared membranes. Membrane potential, permselectivity, transport number and areal membrane resistance all showed decreasing trends by the increase in NPHCs blend ratio in casting solution. These results indicated that the prepared membrane has good prospective and great potential for desalination in electrodialysis applications.     

Swelling and mechanical properties of superporous hydrogels of poly(acrylamide-co-acrylic acid)/polyethylenimine interpenetrating polymer networks

Swelling and mechanical properties were investigated for superporous hydrogels (SPHs) of poly(acrylamide-co-acrylic acid)/polyethylenimine (P(AM-co-AA)/PEI) interpenetrating polymer networks (IPNs). Gelation kinetics of SPHs changed significantly according to the acidic condition of reactant. The compressive strength of neutralized SPHs decreased monotonically with AA concentration, while the maximum swelling was observed around the AA weight fraction of 0.4 for all PEI concentrations. The SPH samples composed of high concentrations of AA and PEI were easily cracked in water due to the swelling stress developed during water uptake. The swelling kinetics decreased with increasing PEI and PAA concentrations because of the high molecular entanglement and network density associated with ionic interaction between PAA and PEI molecules. For non-neutralized SPHs, the equilibrium water uptake decreased but the compressive strength increased with PEI and PAA concentrations by simple plasticization effect.     

Polyethylenimine–polyepichlorohydrin interpolymer for chelating ion-exchange membrane

Polyethylenimine membranes consisting of linear polyethylenimine (PEI) and polyepichlorohydrin (PECH) were prepared by casting and heating an N,N-dimethylformamide solution of the two polymers under nitrogen at 100°C for 60 min. The membrane was also prepared by a heat-press method in a conventional manner. The cast membrane obtained was transparent. The membrane has a crosslinked structure due to the reaction between the secondary amino groups in PEI and the chloromethyl groups in PECH. Although a larger feed ratio of PEI/PECH gave membranes with a larger adsorption capacity for Cu²⁺ ions, the optimum ratio was 40/100 with respect to mechanical properties. A belt conveyor system using the PEI membrane was able to transport Cu²⁺ ions from one bath to another. In a diffusion dialysis against 1N HCl, the PEI membrane crosslinked rather tightly showed a specific ion-selective transfer character. For example, in Cu²⁺–Ca²⁺ system the permeability ratio P_cu/P_ca was about 3.8. The selectivity arises from the difference between affinities (extractabilities) of PEI toward metal ions. The selectivity was changed depending on the pH value.