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As a new kind of 2D nanomaterials, graphene oxide (GO) with 2–4 layers was fabricated via a modified Hummers method and used for the preparation of pervaporation (PV) membranes. Such GO membranes were prepared via a facile vacuum-assisted method on anodic aluminium oxide disks and applied for the dehydration of butanol. To obtain GO membranes with high performance, effects of pre-treatments, including high-speed centrifugal treat-ment of GO dispersion and thermal treatment of GO membranes, were investigated. In addition, effects of oper-ation conditions on the performance of GO membranes in the PV process and the stability of GO membranes were also studied. It is of benefit to improve the selectivity of GO membrane by pre-treatment that centrifuges the GO dispersion with 10000 r·min?1 for 40 min, which could purify the GO dispersion by removing the large size GO sheets. As prepared GO membrane showed high separation performance for the butanol/water system. The separation factor was 230, and the permeability was as high as 3.1 kg·m?2·h?1 when the PV temperature was 50 °C and the water content in feed was 10%(by mass). Meanwhile, the membrane still showed good stabil-ity for the dehydration of butanol after running for 1800 min in the PV process. GO membranes are suitable candidates for butanol dehydration via PV process. 相似文献
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Pervaporation (PV) is an emerging separation technique for liquid mixture. Mixed matrix membranes (MMMs) often demonstrate trade-off relationship between separation factor and flux. In this study, by changing the organic linkers (2-methyl imidazolate, imidazole-2-carboxaldehyde, 2-ethyl imidazolate), ZIF-8, ZIF-90 and MAF-6 were prepared and filled in polydimethylsiloxane (PDMS) membranes for dealcoholization of 5% (mass) n-butanol solution, and the membranes properties and pervaporation performances were adjusted. Compared with the pure PDMS membrane, the addition of ZIF-8 resulted in a 9% increase in flux (1136 g·m-2·h-1) and a 22.5% increase in separation factor (28.3), displaying anti-trade-off effect. For the MAF-6/PDMS MMMs (2.0% mass loading), the pervaporation separation index (PSI) and separation factor were 32347 g·m-2·h-1 and 58.6 respectively (increased by 34% and 154% in contrast with that of the pure PDMS membrane), and the corresponding permeation flux was 552 g·m-2·h-1, presenting great potential in the removal butanol from water. It was deduced that the large aperture size combined with moderate hydrophobicity of metal-organic frameworks (MOFs) favor the concurrent increase in permeability and selectivity. 相似文献
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Five kinds of polyimide membranes have been synthesized from two dianhydrides (including pyromellitic dianhydride (PMDA) and 3, 3′4, 4′-benzophenonetetracarboxylic dianhydride (BTDA)) and three diamines (including 4,4′-diaminodiphenylether (ODA), 4,4′-diaminodiphenylmethane (MDA) and phenylenediamine (PDA)) via a two-step method, and the properties of polyimide membranes have been characterized by experimental techniques. The permeation experiments of water/ethanol mixtures through the polyimide membranes were carried out at 318, 328, 338 and 348 K. All polyimide membranes in this paper are water selectivity, and the flux of mixtures through MDA-based polyimide membranes is higher than that of solvents through PDA-based polyimide membranes with the same diahydrides, while the separation factor exhibits the opposite variation order at the same temperature. The total flux and the partial water flux through all the membranes increase with the operating temperature rising, and the relationships between the flux and temperature can be described by Arrhenius equation. According to the Arrhenius equation, the active energies of water/ethanol in PMDA-ODA, PMDA-MDA, BTDA-PDA, BTDA-ODA and BTDA-MDA membranes are 35.1, 52.6, 16.4, 19.8 and 27.1 kJ/mol, respectively, and those for partial water flux in PMDA-ODA, PMDA-MDA, BTDA-ODA and BTDA-MDA are 36.1, 46.8, 19.9 and 27.9 kJ/mol, respectively. The separation factors of mixtures in the polyimide membranes but no PMDA-MDA show the trend of increase with the operating temperature. The partial flux of ethanol increases while the separation factor of mixtures in PMDA-MDA decreases with the operating temperature, and the activation energy for partial ethanol flux in PMDA-MDA is 75.2 kJ/mol. In addition, pervaporation performances were attempted to correlate independently with the fractional free volume (FFV) and mean interchain distance (d-spacing) of polymers. It is shown that lnJ increases with d-spacing, while there is no clear relationship between the flux and FFV. 相似文献
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In this study, an in situ crosslinked polydimethylsiloxane/brominated polyphenylene oxide (c‐PDMS/BPPO) membrane on ceramic tube has been prepared for the recovery of butanol by pervaporation. A series of BPPO with different bromide‐substituted ratio were firstly synthesized through Wohl–Ziegler reaction. BPPO and PDMS were sequentially assembled and in situ crosslinked to form the final c‐PDMS/BPPO membrane. The results of solid‐state NMR and Differential Scanning Calorimeter demonstrated that the c‐PDMS/BPPO copolymer has a crosslinking structure and the SEM result proved the coverage of ceramic tube by copolymer layer. The effects of preparation conditions including dipping time and bromide‐substituted ratio of BPPO on the membrane performance were studied. The pervaporation experiments of butanol–water mixture indicated that the c‐PDMS/BPPO membrane exhibited an acceptable flux of 220 g·m?2·h?1 and high separation factor of 35 towards butanol, when the bromide‐substituted ratio was 34 wt % and the dipping time was 1.33 h. Moreover, the c‐PDMS/BPPO membrane performed excellent stability in an about 200 h continuous butanol recovery, as compared to the PDMS membrane. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40004. 相似文献
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E. Korin I. Ladizhensky E. Korngold 《Chemical Engineering and Processing: Process Intensification》1996,35(6):451-457
Hydrophilic ion-exchange membranes based on sulfonated polyethylene hollow fibers were manufactured, and their suitability for a water pervaporation process was studied for possible application in water desalination systems. The effects of the following parameters on the average water flux were determined: membrane properties (diameter (0.4–1.8 mm) and wall thickness (0.05–0.18 mm)); charge density (0.6–1.2 meq g−1); and operating conditions (brine inlet temperature (30–68°C), air sweep velocity (0–6 m s−1), and salt concentration in the feed brine (0–3 M)). A water flux of 0.8–3.3 kg m−2 h−1 was obtained using this type of hollow fiber with an inlet brine temperature of 25–65°C. It was found that, for our application, the optimal specifications for the ion-exchange hollow fibers were an outside diameter of 1.2 mm, a wall thickness of 0.1 mm, and an ion-charge density of about 1.0 meq g−1. This information is required as basic data for the design of a prototype water desalination system based on a pervaporation system that uses this type of ion-exchange hollow fiber membrane. 相似文献
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Choong-Kyun Yeom James M. Dickson Michael A. Brook 《Korean Journal of Chemical Engineering》1996,13(5):482-488
A new silicone pervaporation membrane for the removal of one of trace organies, 1,2-dichloroethane from water has been developed
using polydimethylsiloxane (PDMS) and oligomeric silylstyrene as a crosslinking agent of PDMS. Optimal conditions for fabricating
the best membrane were determined from swelling measurements ard pervaporation experiments and then the membrane was characterized
at different membrane thickness and operating conditions. In the pervaporation separation of 55–70 ppm of l,2-dichlorocthanc
aqueous mixtures, the developed membrane has flux of 2.5–330 g/(m2.h) and selectivity of 230–1750 depending on membrane thickness, permeate pressure and operating Temperature. Water permeation
through thin membrane was found to be subjected to significant desorption resistance, while the desorption resistance and
thermodynamic factors as well as the concentration polarization of the organic at the boundary layer in feed can affect the
organic permeation, depending on membrane thickness. Selectivity change with permcaic pressure depends on membrane thickness:
at small membrane thickness range, selectivity increases with permeate pressure and at large thickness region it decreases.
From the Arrhenius plots of each component fluxes, the permeation activation energies were determined. Through an analysis
of the permeation activation energies of each components, the desorption resistance as well as the effects of the thermodynamic
factors on permeation was qualitatively characterized. 相似文献
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Asymmetric bilayer membranes have been regarded as ideal wound dressings for skin regeneration. Our previous work reported the potential advantages of polydimethylsiloxane modified gelatin/silicone rubber (PGE/SR) asymmetric bilayer membrane as a wound dressing. However, it is still unknown whether the proportion of the two components of the bilayer membrane has a prominent influence on its relevant performance. Herein, various PGE/SR membranes with different PGE:SR weight ratios (100:25, 100:50 and 100:100) were fabricated through a self‐stratification method driven by surface tension gradients. Subsequently, the effects of the PGE:SR ratios on the relevant performance (i.e. porous structure, mechanical properties, degradability and biocompatibility) of PGE/SR membranes were systematically investigated. The current results demonstrate that the separating force between the PGE and SR components was reduced significantly on increasing the content of SR, and in particular the PGE/SR1 membrane (100:25) exhibited a well‐defined asymmetric bilayer structure with high porosity, appropriate toughness, water uptake, swelling ratio and water permeability. Concomitantly, the maximum weight loss for the PGE/SR1 membrane was ca 70.65% after 9 days of enzymatic degradation, which met the typical healing period of a normal skin wound. In addition, both the original and degraded PGE/SR1 membrane possessed favorable cytocompatibility in vitro, suggesting its potential application as a wound dressing. © 2019 Society of Chemical Industry 相似文献
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Preparation of zeolite-coated pervaporation membranes for the integration of reaction and separation 总被引:1,自引:0,他引:1
T.A. Peters J. van der Tuin C. Houssin M.A.G. Vorstman N.E. Benes Z.A.E.P. Vroon A. Holmen J.T.F. Keurentjes 《Catalysis Today》2005,104(2-4):288-295
Pervaporation is a promising option to enhance conversion of reversible condensation reactions, generating water as a by-product. In this work, composite catalytic membranes for pervaporation-assisted esterification processes are prepared. Catalytic zeolite H-USY layers have been deposited on silica membranes by dip-coating using TEOS and Ludox AS-40 as binder material. Membrane pre-treatment and the addition of binder to the dip-coat suspension appear to be crucial in the process. Tuning of catalytic layer thickness is possible by varying the number of dip-coat steps. This procedure avoids failure of the coating due to the high stresses, which can occur in thicker coatings during firing. In the pervaporation-assisted esterification reaction the H-USY coated catalytic pervaporation membrane was able to couple catalytic activity and water removal. The catalytic activity is comparable to the activity of the bulk zeolite catalyst. The collected permeate consists mainly of water and the loss of acid, alcohol and ester through the membrane is negligible. The performance of the membrane reactor is mainly limited by reaction kinetics and can be improved by using a more active catalyst. 相似文献
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Yueh-Hua Wang Kueir-Rarn Lee Der-Jang Liaw Juin-Yih Lai 《Journal of Polymer Research》1998,5(1):31-36
The separation of water/alcohol mixtures was carried out using a series of fluorine-containing aromatic polyamide membranes.
Aromatic polyamides were prepared by direct polycondensation of fluorine-containing diamine (2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,
BAPPH) and various aromatic diacids. The separation factor toward water increased when the feed ethanol concentration was
increased. The solubility of ethanol in aromatic polyamide membrane is higher than that of the water, but the diffusivity
of water across the membrane is higher than that of alcohols. A separation factor of 83 and a permeation rate of 262 g/m2h with a 90 wt% feed ethanol concentration at 25 °C was obtained. 相似文献
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NQ硅树脂增强加成型室温硫化硅橡胶 总被引:11,自引:0,他引:11
研究了MQ硅树脂对加成型室温硫化硅橡胶的增强作用。结果表明,含乙烯基的MQ硅树脂对加成型室温硫化硅橡胶的增强作用明显,硅橡胶的透明性很好。硅橡胶的强度随着MQ硅树脂中乙烯基含量的增加先增加而后下降。SiH/SiCH=CH2(摩尔比)为1.2 ̄1.5时,硅橡胶具有较好的力学性能。 相似文献
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以六甲基二硅氧烷、四甲基二硅氧烷、正硅酸乙酯、γ-脲丙基三甲氧基硅烷为主要原料合成脲基含氢硅树脂(UHMQ),并将其加入到乙烯基硅橡胶中作为耐热助剂,考察了UHMQ用量对室温硫化硅橡胶耐热性能及力学性能的影响。结果表明,当UHMQ的用量为8份时,硅橡胶复合材料的初始分解温度最高可达414.79℃。当UHMQ的用量为6份和8份时,在200,300,400℃下热空气老化24 h硅橡胶复合材料的质量损失率明显下降,且热空气老化24 h后仍保持一定弹性。UHMQ的加入可提高硅橡胶复合材料的力学性能,当UHMQ的用量为6份时,硅橡胶复合材料的剪切强度达到最大值。 相似文献
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Separation of acetic acid/water mixtures by pervaporation was attempted by silicone rubbercoated polyetherimide membranes. In particular, the effect of the pore size of the polyetherimide membrane and the condition of silicone rubber coating on the performance of the composite membrane was investigated. It was found that the composite membrane could become either water selective or acetic acid selective, depending on the pore size of the support membrane and the condition of the silicone rubber coating. Thus, the overall performance of the composite membrane can be governed, either by the top coated layer or by the bottom support layer. 相似文献
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Six mixed matrix membranes (MMMs) were prepared using zeolites of 4A and ZSM-5 incorporated in polyimide of Matrimid 5218. Effects of filler type on membrane morphology and pervaporation performance of MMMs were investigated using isopropanol dehydration. In addition, effects of operating temperature (30, 40, 50, and 60 °C), feed water concentration (10, 20, 30, and 40 wt.%) and permeate side pressure (0 and 15 torr) on pervaporation performance were studied. Scanning electron microscopy (SEM) analysis showed there were good adhesion between the fillers and the polymer matrix. Zeolite 4A has a better contact with the polymer phase and thereby nearly no void is formed in the MMM structure. Pervaporation were performed based on L16 array of Taguchi method for design of experiments. The results showed that the best separation condition is achieved at temperature, feed water concentration, and permeate pressure of 30 °C, 10 wt.% water and 0 torr, respectively. Selectivities of zeolites 4A and ZSM-5 filled MMMs were calculated as 8991 and 3904 compared with 1276 measured for the neat Matrimid 5218 membrane. Permeation rates of the zeolite 4A and ZSM-5 filled MMMs and the neat polymeric membrane were found to be 0.018, 0.016, and 0.013 kg/m2 h, respectively. 相似文献
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Kansiri Pakkethati Ardia Boonmalert Thanyalak Chaisuwan Sujitra Wongkasemjit 《Desalination》2011,(1):73
Polybenzoxazine membranes have been successfully synthesized from bisphenol-A, formaldehyde, and three different types of diamines: hexa-methylenediamine (hda), tetraethylenepentamine (tepa), and tetraethylenetriamine (teta) via a facile “quasi-solventless” method. To study the possibility of using polybenzoxazine membranes in a pervaporation system for ethanol–water separation, the sorption and swelling behaviors of these membranes were investigated. When hda was used as a reactant, the resulting polybenzoxazine membranes showed the best service time and interestingly only water permeated the membranes under the studied operation conditions. The total permeation flux was found to be 1.52 kg/m2h and the separation factor was higher than 10,000. Additionally, an increased permeation flux was achieved by raising the temperature of the feed solution and decreasing the membrane thickness. The optimum conditions for this study were 70 °C for the feed mixtures when a 200 μm thick was used. 相似文献
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In this study, poly(dimethyl siloxane) (PDMS)/poly(vinylidene fluoride) (PVDF), poly(phenyl methyl siloxane) (PPMS)/PVDF, poly(ethoxy methyl siloxane) (PEOMS)/PVDF, and poly(trifluropropyl methyl siloxane) (PTFMS)/PVDF composite membranes were prepared. The different functional compositions of these membranes were characterized by Fourier transform infrared spectroscopy. The surfaces and sections of these membranes were investigated by scanning electron microscopy. The hydrophobicity at the membrane surface was assessed with contact angle measurement. Swelling experiments were carried out to investigate the swelling behavior of these membranes. The composite membranes prepared in this study were used in the pervaporation separation of ethanol/water mixtures, and their separation performances were compared. The results show that the separation performances of these membranes were strongly related to the silicone rubber components and composition, the total fluxes decreased in the following order: PDMS > PPMS > PEOMS > PTFMS. The separation factor followed the following order: PPMS > PEOMS > PDMS > PTFMS (5 wt % ethanol at 40°C). In addition, the effects of the feed temperature (40–70°C) and feed composition (5–20 wt %) on the separation efficiency were investigated experimentally. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献