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聚环氧乙烷(PEO)/壳聚糖(CS)共混膜的醇—水渗透蒸发性能研究 总被引:1,自引:0,他引:1
研究了EtOH-H2O,n-PrOH-H2O,i-PrOh-H2O体系在CS膜和PEO/CS共混膜中的渗透蒸发性能。讨论了料液温度、料液浓度、共混膜组成对分离性能的影响,结果发现PEO的掺入能大大提高CS膜的渗透通量,而分离因子下降。同时从膜材料的聚集态结构出发对相关的渗透蒸发行为进行了讨论。对于PEO/CS共混膜,膜内自由体积的大小是影响分离性能的主要因素,小分子在膜中的渗透蒸发行全为主要是由扩 相似文献
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研究了EtOH-H2O,n-PrOH-H2O,i-PrOH-H2O体系在CS膜和PEO/CS共混膜中的渗透蒸发性能。讨论了料液温度、料液浓度、共混膜组成对分离性能的影响,结果发现PEO的掺入能大大提高cs膜的渗透通量;而分离因子下降。同时从膜材料的聚集态结构出发对相关的渗透蒸发行为进行了讨论。对于PEO/CS共混膜,膜内自由体积的大小是影响分离性能的主要因素,小分子在膜中的渗透蒸发行为主要是由扩散过程控制的。本文还研究了PEO的掺入对壳聚塘膜强度的影响以及利用DSC谱研究PEO掺入后壳聚糖膜聚集态结构的变化。 相似文献
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酸处理Silicalite—Ⅰ沸石填充硅橡胶渗透蒸发分离膜 总被引:1,自引:1,他引:0
研究酸处理Slilicalite-Ⅰ沸石对有机溶剂、水的吸附、脱附性质,酸处理Silicalite-Ⅰ填充硅橡胶对低浓度有机溶剂水溶液的渗透蒸发分离性能以及填充膜的力学性能。实验结果表明,在硅橡胶胶膜中填充酸处理Silicalite-Ⅰ沸石能改善膜对有机溶剂-水混合物的分离性能,且分离性能的改善与沸石在膜中的填充量以及硅橡胶的品种有关。另外,沸石的填充也有利于改善膜的力学性能。 相似文献
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干/湿相转换法制备聚芳醚砜致密皮层不对称膜 总被引:2,自引:0,他引:2
以聚芳醚砜为膜材料,采用干/湿相转换法.在非挥发性溶剂-挥发性添加剂以及挥发性溶剂/共溶剂-弱挥发性添加剂两种溶剂体系中研究了致密皮层不对称膜的制备和形成条件,并对它们的结构及氮、氢气体透过性能进行了测试。结果表明,采用前一种溶剂体系。虽然可以在一定范围内控制膜平均孔径的变化,却难以得到致密皮层不对称膜。而后一种溶剂体系,在控制铸膜液组成、适当的制膜条件下可以得到具有海绵状支撑结构的不对称气体分离膜。 相似文献
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随着膜分离技术、质子交换膜燃料电池技术和液流电池储能技术等的发展,膜材料的研究开发也越来越受到人们的重视。杂萘联苯聚芳醚是一类性能优良的高分子膜材料,由于分子主链上含有全芳非共平面扭曲链结构,具有较好的耐化学稳定性和耐热性,且可溶解于N-甲基-2-吡咯烷酮、N,N-二甲基乙酰胺等常用制膜溶剂,在耐高温分离膜和离子交换膜... 相似文献
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《Journal of membrane science》1997,127(2):185-202
Three different types of blend membranes based on chitosan and polyacrylic acid were prepared from homogeneous polymer solution and their performance on the pervaporation separation of water-ethanol mixtures was investigated. It was found that all membranes are highly water-selective. The temperature dependence of membrane permselectivity for the feed solutions of higher water content (>30 wt%) was unusual in that both permeability and separation factor increased with increase in temperature. This phenomenon might be explained from the aspect of activation energy and suggested that the sorption contribution to activation energy of permeation should not always be ignored when strong interaction occurs in the pervaporation membrane system.A comparison of pervaporation performance between composite and homogeneous membranes was also studied. Typical pervaporation results at 30°C for a 95 wt% ethanol aqueous solution were: for the homogeneous membrane, permeation flux = 33 g/m2 h, separation factor = 2216; and for the composite membrane, permeation flux = 132 g/m2 h, separation factor = 1008. A transport model consisting of dense layer and porous substrate in series was developed to describe the effect of porous substrate on pervaporation performance. 相似文献
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Selective facilitated transport of benzene across supported and flowing liquid membranes containing silver nitrate as a carrier 总被引:1,自引:0,他引:1
Masaaki Teramoto Hideto Matsuyama Tomokichi Yonehara 《Journal of membrane science》1990,50(3):269-284
Separation of benzene from cyclohexane was performed using two types of liquid membranes, i.e., a supported liquid membrane and a flowing liquid membrane. Silver nitrate was used as the carrier of benzene. The permeation rate of benzene increased with increasing carrier concentration, and the separation factor, which is defined as the ratio of permeability of benzene to that of cyclohexane, was about 630 when the supported liquid membrane prepared by immobilizing 4 mol/L aqueous silver nitrate solution in cellulose filter paper was used. Compared with the supported liquid membrane, the flowing liquid membrane, where a liquid membrane solution was forced to flow in a thin compartment between two microporous membranes, showed one order of magnitude higher permeation rate at high flow rate of the membrane solution. The flowing liquid membrane was very stable and no noticeable decrease in both the flux and the selectivity was observed during 11 days operation. The mechanisms of the facilitated transport of benzene through both types of liquid membrane were proposed. The permeation rate and the selectivity were quantitatively simulated by the proposed model. 相似文献
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Novel nanocomposite pervaporation membranes composed of poly(vinyl alcohol) and chitosan-wrapped carbon nanotube 总被引:1,自引:0,他引:1
Fubing Peng Fusheng Pan Honglei Sun Lianyu Lu Zhongyi Jiang 《Journal of membrane science》2007,300(1-2):13-19
Novel nanocomposite membranes (PVA–CNT(CS)) were prepared by incorporating chitosan-wrapped multiwalled carbon nanotube (MWNT) into poly(vinyl alcohol) (PVA). To further explore the intrinsic correlation between pervaporation performance and free volume characteristics, molecular dynamics simulation was first introduced to qualitatively analyze the contribution of carbon nanotube incorporation on improving free volume characteristics of the nanocomposite membranes. Secondly, the pervaporation performance of PVA–CNT(CS) nanocomposite membranes was investigated using permeation flux and separation factor as evaluating parameters. For benzene/cyclohexane (50/50, w/w) mixtures at 323 K, permeation flux and separation factor of pure PVA membrane are only 20.3 g/(m2 h) and 9.6, respectively, while the corresponding values of PVA–CNT(CS) (CNT content: 1%) nanocomposite membrane are 65.9 g/(m2 h) and 53.4. In order to explain the simultaneous increase of permeation flux and separation factor, as well as to check the calculation reliability of molecular dynamics simulation, positron annihilation lifetime spectroscopy (PALS) analysis was employed. 相似文献
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Cardo polyetherketone (PEK-C) composite membranes were prepared by casting glutaraldehyde (GA) cross-linked sulfonated cardo polyetherketone (SPEK-C) or silicotungstic acid (STA) filled SPEK-C and poly(vinyl alcohol) (PVA) blending onto a PEK-C substrate. The compatibility between the active layer and PEK-C substrate is improved by immersing the PEK-C substrate in a GA cross-linked sodium alginate (NaAlg) solution and using water–dimethyl sulfoxide (DMSO) as a co-solvent for preparing the STA-PVA-SPEK-C/GA active layer. The pervaporation (PV) dehydration of acetic acid shows that permeation flux decreased and separation factor increased with increasing GA content in the homogeneous membranes. The permeation flux achieved a minimum and the separation factor a maximum when the GA content increased to a certain amount. Thereafter the permeation flux increased and the separation factor decreased with further increasing the GA content. The PV performance of the composite membranes is superior to that of the homogeneous membranes when the feed water content is below 25 wt%. The permeation activation energy of the composite membranes is lower than that of the homogeneous membranes in the PV dehydration of 10 wt% water in acetic acid. The STA-PVA-SPEK-C-GA/PEK-C composite membrane using water–DMSO as co-solvent has an excellent separation performance with a flux of 592 g m−2 h−1 and a separation factor of 91.2 at a feed water content of 10 wt% at 50 °C. 相似文献
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具有界面交联结构藻酸钠复合膜的制备与性能 总被引:1,自引:1,他引:0
报道了一种具有界面交联结构的新型藻酸钠复合膜及其对醇水和其它有机物水体系的渗透汽化分离性能.该膜的活性层为藻酸钠,支撑层为氨化聚丙烯腈(PAN)多孔膜,在这两层之间存在着界面交联结构.研究了PAN多孔膜的水解时间、进行氨基化的二元胺种类及浓度对复合膜分离性能的影响,用己二胺进行氨基化所得到的复合膜的分离性能明显优于用乙二胺的结果.扫描电镜照片显示水解及氨基化改变了PAN超滤膜的孔结构,这也是影响新型复合膜性能的一个重要原因. 相似文献
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使用均质和复合壳聚糖膜对二氧六环-水和丙酮-水溶液的渗透汽化分离性能进行了研究。结果显示,该膜对两种混合物的分离有很高的选择性和渗透速率。考察料液组成和温度对均质膜分离的影响,随温度升高,分离系数与通量同时增加。从渗透速率与温度的Arrhenius关系求得总的和各组分的表现渗透活化能,复合膜在保持高选择性的同时,渗透速率大幅度提高。 相似文献
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A novel alcohol dehydration membrane with a three layer structure has been prepared. The top layer is a thin dense film of chitosan (CS), and the support layer is made of microporous polyacrylonitrile (PAN). Between the dense and microporous layer, there is an intermolecular cross-linking layer. This novel composite membrane has a high separation factor of more than 8000 and a good permeation rate of 0.26 kg/m2 h for the pervaporation of 90 wt% ethanol aqueous solution at 60°C, 0.8 kg/m2 h flux for a n-PrOH/water system and around 1 kg/m2 h flux for an i-PrOH/water system using 80 wt% alcohol concentration at 60°C. The separation factor for both cases is more than 105. The separation performance varies with feed composition, operating temperature and conditions of membrane preparation. The results show that the separation factor and flux of this membrane increase with raising the operating temperature. At the same time, the crosslinking layer improves durability of the composite membrane, and the pervaporation performance can be adjusted by changing the structure of the cross-linking layer. The cross section of the composite membrane has been examined by SEM. 相似文献
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A model is developed to explain the behavior of composite gas separation membranes which consist of a porous asymmetric substrate of one polymer, and a coating of a second polymer. An analogy between gas permeation and electrical flow is made, and the various portions of the composite membrane are described in terms of their resistance to gas permeation. It is shown that substrate porosity can vary significantly without altering the separating properties of such a composite, and that substrate and coating properties can be matched to optimize the flux and separation factor. Several major problems previously associated with the development of useful hollow fibers for gas separation are discussed, and it is shown that the use of Resistance Model composites can help to resolve these problems. 相似文献
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《Journal of membrane science》1997,124(1):53-62
Homogeneous and composite chitosan based membranes were prepared by the solution casting technique. The membranes were investigated for the pervaporation dehydration of isopropanol-water systems. The effects of feed concentration and temperature on the separation performance of the membranes were studied. In terms of the pervaporation separation index (PSI), the composite membrane was more productive than the homogeneous membrane for pervaporation of feed with high isopropanol content. It was observed that permeation increased and the separation factor decreased with the temperature. Modification of the homogeneous chitosan membrane by chemical crosslinking with hexamethylene diisocyanate improved the permselectivity but reduced the permeation rate of the membrane. 相似文献
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This study deals with the separation of n-butanol from aqueous solutions by pervaporation. The effects of feed concentration, temperature, and membrane thickness on the separation performance were investigated. Over the low feed butanol concentration range (0.03–0.4 wt%) studied, the butanol flux was shown to increase proportionally with an increase in the feed butanol concentration, whereas the water flux was relatively constant. An increase in temperature increased both the butanol and water fluxes, and the increase in butanol flux was more pronounced than water flux, resulting in an increase in separation factor. While the permeation flux could be enhanced by reducing the membrane thickness as expected for all rate-controlled processes, the separation factor was compromised when the membrane became thinner. The effect of membrane thickness on the separation performance was analyzed taking into account the boundary layer effect. This could not be fully attributed to the concentration polarization, which was found not significant enough to dominate the mass transport. A variation in the membrane thickness would vary the local concentration of permeant inside the membrane, thereby affecting the permeation of butanol and water differently. Thus, caution should be exercised in using permeation flux normalized by a given thickness to predict the separation performance of a membrane with a different thickness because the membrane selectivity can be affected by the membrane thickness even in the absence of boundary layer effect. 相似文献