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以聚己二酸1,4-丁二醇酯二醇(PBA-2000)和甲苯二异氰酸酯(TDI)为主要原料合成水性聚氨酯膜,并对苯/环己烷混合液渗透蒸发性能进行测试,讨论了苯/环己烷混合体系的渗透蒸发分离过程特点。结果表明,当膜厚度增大时,分离因子提高而渗透通量随之下降,这个变化趋势在膜较薄时很明显,达到一定厚度后则变化比较平缓;膜下游侧真空度提高会同时提高膜的分离因子和通量;增大料液中苯的浓度,提高料液温度会提高通量并降低分离因子。液体被分离组分在渗透蒸发膜中经历了吸附溶胀-膜内汽化-气体扩散的质量传递过程,“干区”对分离的影响作用更加显著。 相似文献
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二元水溶液在渗透蒸发膜中的传质模型 总被引:1,自引:0,他引:1
对二元水溶液在渗透蒸发膜中的传质过程进行了研究,基于Flory Huggins高分子热力学理论和Fujita自由体积理论建立了改进的溶解 扩散模型。在该模型中考虑了组分间相互作用,组分体积分数、温度、膜材料和渗透物特性对传质过程的影响,考察了组分体积分数对相互作用参数的影响,膜材料对水的溶解选择性的影响,原料液组分体积分数、操作温度以及膜厚对渗透通量和分离因子的影响。 相似文献
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以聚二甲基硅烷为预聚体,正硅酸乙酯为交联剂,二丁基二月桂酸锡为催化剂,三氯甲烷或正庚烷为溶剂,通过相转化法制备得到了空白聚二甲基硅氧烷(PDMS)膜和聚环糊精(CDP)填充PDMS(CDP-f-PDMS)膜.考察了空白PDMS膜和CDP-f-PDMS膜对苯酚水溶液的渗透蒸发分离性能,证明填充膜优于空白膜.还分别考察了溶剂类型、填充剂用量等制膜因素和操作温度、原料液流量、原料液浓度等操作因素对PDMS膜的渗透蒸发分离性能的影响.当温度为60℃,CDP填充量为1%(质量)时,CDP-f-PDMS膜的渗透通量和分离因子分别可达32.0 g8226;m-28226;h-1和7.2. 相似文献
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交联壳聚糖渗透蒸发膜的制备及其在偏二甲肼/水体系分离中的应用 总被引:1,自引:0,他引:1
采用壳聚糖为原料,聚酯无纺布为支撑层,用戊二醛交联制备了高选择性、高通量的交联壳聚糖渗透蒸发复合膜.考察了料液浓度、料液温度、膜厚等对偏二甲肼/水体系分离性能的影响.结果表明:在料液温度为10℃,膜厚度为25 μm,进料液中偏二甲肼的质量分数为50%时,改性复合膜的分离因子最高达到5.25,渗透通量可达167 g/(m... 相似文献
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Pervaporation removal of volatile organic compounds from aqueous solutions using the highly permeable PIM‐1 membrane
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Xin Mei Wu Qiu Gen Zhang Faizal Soyekwo Qing Lin Liu Ai Mei Zhu 《American Institute of Chemical Engineers》2016,62(3):842-851
Wastewater containing volatile organic compounds (VOCs) is generated in various industrial processes and is seriously harmful to the natural environment and human health. Its treatment has become extremely important due to increasing environment concerns. Here, a high permeable membrane for fast and high‐efficient VOCs removal from aqueous solutions by pervaporation is reported. The as‐prepared PIM‐1 membrane allows ultrafast permeation of VOCs and exhibits excellent VOCs selectivity, particularly for ethyl acetate, dimethyl ether, and acetonitrile. Typically, the PIM‐1 membrane exhibits an ultrahigh flux and separation factor of 39.5 kg μm m?2 h?1 and 189, respectively, in the pervaporation of 1.0 mol% aqueous ethyl acetate solution. Furthermore, the solubility‐diffusion mechanism is revealed in the pervaporation of 10 kinds of 1.0 mol% VOCs solutions. It is found that the pervaporation performance is affected directly by physicochemical properties of VOCs. Moreover, effects of feed composition and temperature on the pervaporation are studied in details. © 2015 American Institute of Chemical Engineers AIChE J, 62: 842–851, 2016 相似文献
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《分离科学与技术》2012,47(8):1737-1752
Abstract Removal of volatile organic compounds (VOCs) such as 1,2-dichloroethane, trichloroethylene, chlorobenzene and toluene from water solutions through polyetherimide (PEI)-polyethersulfone (PES) blend hollow fiber membranes was investigated by pervaporation (PV) in this work. The separation performances of the membranes were researched by varying the spinning conditions (such as coagulation temperature and air gap distance) for the preparation of the hollow fibers and the operation conditions (such as velocity, concentration, and temperature of feed liquids). For the PEI-PES blend hollow fiber membrane prepared when the air gap was 7 cm and the temperature of coagulation bath was 45°C, it possessed high selectivity to the aqueous solutions containing 0.04 wt.% of VOCs at 20°C. The separation factors to 1,2-dichloroethane, trichloroethylene, chlorobenzene and toluene were 7069, 5759, 3952, and 3205, respectively. It was found that the pervaporation performance of the blend hollow fiber membrane was strongly related to the molecular size of the VOCs. The order of the selectivities was 1,2-dichloroethane > trichloroethylene > chlorobenzene > toluene. 相似文献
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The membranes were prepared by the incorporation of highly hydrophobic silicalite and carbon molecular sieves (CMS) from different precursors into the PDMS casting solutions. The pervaporative removal of VOCs, such as benzene, from aqueous solutions was carried out using the separation factor and permeation flux as the evaluating parameters. The effects of the CMS types and structures, feed concentrations on the pervaporation performance were preliminarily investigated. 相似文献
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Swatilekha Das 《Chemical engineering science》2006,61(19):6454-6467
Polymer membranes are potentially selective for separation of organic compounds from a mixture by pervaporation. A novel crosslinked hydroxyterminated polybutadiene based (HTPB) polyurethane urea (PUU)-poly (methyl methacrylate) (PMMA) interpenetrating network (IPN) membrane has been developed for the selective removal of chlorinated volatile organic compounds (VOCs) such as 1,1,2,2-tetrachloroethane, chloroform, carbon tetrachloride, trichloroethylene present in water in very low concentration by pervaporation. IPNs of different PMMA content and also different crosslink density were used. Since the selective permeation and diffusion of the VOCs through the membrane are dependent on their interaction with the membrane material, their sorption and diffusion behaviors through the membrane were also investigated by swelling the membrane in pure VOCs. The sorption and diffusion behaviors were explained with the help of their solubility parameter data and calculated interaction parameter data of the membrane polymers with the VOCs. From the swelling kinetics data, diffusion coefficients of the VOCs through the membrane were calculated. Diffusion coefficients increased with the increase in crosslink density and PMMA content in the membrane. In pervaporation experiment, concentrations of chlorinated organic compounds in feed were varied from 100 ppm (0.01%) to 1000 ppm (0.1%). All the three IPN membranes showed excellent separation performances of the chlorinated VOCs from water. One IPN containing 26% PMMA (PUU-PMMA-3) produced 88.7% trichloroethylene in permeate, trichloroethylene flux and a separation factor of 7842 from a 0.1% aqueous feed after a pervaporation run of 3 h at . All the three IPN membranes of different compositions have shown the separation performances, viz., flux and separation factor for all the VOCs in the order . 相似文献
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Denis Roizard François Lapicque Eric Favre Christine Roizard 《Chemical engineering science》2009,64(9):1927-1935
Gas treatment by liquid absorption is a well-known process to remove volatile organic compounds (VOCs) from industrial waste gases. Usually the liquid is an organic solvent of high boiling point; however, after VOCs’ absorption it must be regenerated for the possible reuse and this step is classically achieved by heating the liquid. The paper presents the work directed to investigate an alternative regeneration step based on a liquid-vapour membrane separation, i.e. pervaporation. Because most of the energy required in pervaporation processes is consumed to remove the minor component from the initial mixture by selective permeation through the membrane, one can expect a significant energy cut in the operational costs linked to the regeneration of the liquid if the pervaporation step can substitute the heating one. The results reported here show that the technological possibility to use pervaporation is first governed by the stability of the membrane in the absorption liquid. The viability of the overall process is actually controlled by the mutual affinity between the VOCs, the solvent phase and the polymeric material. As a matter of fact, whereas VOCs have to exhibit strong affinities to both the solvent and the membrane material, the polymer has to be well resistant and even repellent to the solvent to avoid the possible sorption in the membrane that would drastically depress the pervaporation efficiency. In other words the membrane transport properties must be specific for the VOCs. This goal was reached following several experimental approaches, going from membrane modifications to the selection of suitable heavy protic solvents. Hence it has been shown for the case of dichloromethane (DCM) that low molecular weights polyalcohols (e.g. glycols) appeared to be suitable media to allow in particular the specific transport of DCM. On the other hand, polydimethylsiloxane (PDMS) based membranes were selected for their stability in these polyglycols and for their marked affinity for DCM. The simulation of the hybrid gas treatment process at pilot-scale was also achieved by a simple model relying on experimental data for both vapour liquid equilibria and permeation flux. A simple comparison of the energy needed to regenerate the heavy solvent by each possible step has also been made. 相似文献
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A polydimethylsiloxane (PDMS) membrane was improved by graft polymerization of 1H,1H,9H-hexadecafluorononyl methacrylate (HDFNMA) by plasma, which had the effect of increasing the selectivity for volatile organic compounds (VOCs). The use of an easy quantitative analysis for the pervaporation through plasma-grafted PDMS membranes was investigated. The degrees of grafting on the inside and reverse side of the grafted PDMS membranes were lower than on the surface. Only part of the HDFNMA sorbed into the PDMS membrane was grafted onto the PDMS membrane. The relationship between the feed concentration and the permeate concentration was observed to be linear. The pervaporation through the grafted PDMS membrane could be used for easy quantitative analysis. The solubility of VOCs for the grafted PDMS membrane was high when compared with the solubility for the PDMS membrane. The grafted PDMS membrane that had high VOC concentrations of the sorbed solution showed an excellent separation performance. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1835–1844, 1999 相似文献
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For the separation of volatile organic compounds (VOCs) from water by pervaporation, three polysiloxaneimide (PSI) membranes were prepared by polycondensation of three aromatic dianhydrides of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), and pyromellitic dianhydride (PMDA) with a siloxane‐containing diamine. The PSI membranes were characterized using 1H‐NMR, ATR/IR, DSC, XRD, and a Rame‐Hart goniometer for contact angles. The degrees of sorption and sorption selectivity of the PSI membranes for pure organic compounds and organic aqueous solutions were investigated. The pervaporation properties of the PSI membrane were investigated in connection with the nature of organic aqueous solutions. The effects of feed concentration, feed temperature, permeate pressure, and membrane thickness on pervaporation performance were also investigated. The PSI membranes prepared have high pervaporation selectivity and permeation flux towards hydrophobic organic compounds. The PSI membranes with 150‐μm thickness exhibit a high pervaporation selectivity of 6000–9000 and a high permeation flux of 0.031–0.047 kg/m2 h for 0.05 wt % of the toluene/water mixture. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2691–2702, 2000 相似文献
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