共查询到20条相似文献，搜索用时 15 毫秒
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Sabrina Gabardo Rosane Rech Marco Antônio Záchia Ayub 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(8):1194-1201
BACKGROUND: The bioconversion of whey into ethanol by immobilized Kluyveromyces marxianus in packed‐bed and fluidized bioreactors is described. Both batch and continuous cultures were analyzed using three different strains of K. marxianus and the effect of the operating mode, temperature, and dilution rates (D) were investigated. RESULTS: All immobilized strains of K. marxianus (CBS 6556, CCT 4086, and CCT 2653) produced similar high yields of ethanol (0.44 ± 0.01 g EtOH g?1 sugar). Significant variations of conversion efficiencies (66.1 to 83.3%) and ethanol productivities (0.78 to 0.96 g L?1 h?1) were observed in the experiments with strain K. marxianus CBS 6556 at different temperatures. High yields of ethanol were obtained in fluidized and packed‐bed bioreactors continuous cultures at different D (0.1 to 0.3 h?1), with the highest productivity (3.5 g L?1 h?1) observed for D = 0.3 h?1 in the fluidized bioreactor (87% of the maximal theoretical conversion), whereas the highest ethanol concentration in the streaming effluent (28 g L?1) was obtained for D = 0.1 h?1. Electronic micrographs of the gel beads showed efficient cell immobilization. CONCLUSION: Batch and continuous cultivations of immobilized K. marxianus in fluidized and packed‐bed bioreactors enable high yields and productivities of ethanol from whey. Copyright © 2012 Society of Chemical Industry 相似文献
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采用PDMS膜生物反应器和丙酮丁醇梭菌进行了生产ABE的封闭循环连续发酵实验,研究了发酵和渗透汽化分离连续耦合条件下的发酵动力学行为。发酵-分离连续耦合实验运行持续时间长达 192 h。运行过程中,细胞浓度维持在 0.84~4.00 g/L,发酵液中ABE的总浓度为5.14~17.54 g/L,葡萄糖浓度大约为16.08~35.15 g/L,总体积产率为0.36 g/(L?h)。实验结果表明,膜生物反应器系统运行稳定,发酵-渗透汽化分离连续耦合生产ABE的操作模式具有可行性和优越性。 相似文献
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A new blended membrane was prepared and tested by pervaporation of light oil, a mixture of five alcohols plus water. The blended membrane was synthesized by blending poly(vinyl alcohol) and poly(acrylic acid‐co‐maleic acid) sodium salt in the presence of sulfuric acid to dope the reaction. We tested several membranes in order to choose the adequate composition to have the best permselectivity. The PVA(60)–PAA‐co‐maleic acid(40) membrane was selected as it was found to be highly selective. Sorption experiments were performed using binary and ternary water–alcohol solutions. The influence of temperature and feed composition on the selectivity and flux in pervaporation was investigated for two different binary mixtures (water/ethanol, water/isobutanol) and one ternary system (water/ethanol/isobutanol). This membrane presents good permselective properties, high water flux, and good selectivity and can even be used for high‐water activities The performances of this new membrane were compared to those obtained with the PVA(90)–PAA(10) membrane synthesized recently: The fluxes observed for the water–ethanol separation were of the same order of magnitude but the selectivity was found to be much higher. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1709–1716, 2002 相似文献
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采用PDMS膜生物反应器和丙酮丁醇梭菌进行了生产ABE的封闭循环连续发酵实验,研究了发酵和渗透汽化分离连续耦合条件下的发酵动力学行为。发酵-分离连续耦合实验运行持续时间长达192 h。运行过程中,细胞质量浓度维持在0.84～4.00 g/L,发酵液中ABE的总质量浓度为5.14～17.54 g/L,葡萄糖质量浓度大约为16.08～35.15 g/L,总体积产率为0.36 g/(L.h)。结果表明,膜生物反应器系统运行稳定,发酵-渗透汽化分离连续耦合生产ABE的操作模式具有可行性和优越性。 相似文献
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G. A. Polotskaya T. K. Meleshko I. G. Sushchenko A. V. Yakimansky A. Yu. Pulyalina A. M. Toikka Z. Pientka 《应用聚合物科学杂志》2010,117(4):2175-2182
Polyimide–polyaniline nanocomposites were obtained by mixing poly{[4,4′‐bis(4″‐N‐phenoxy)diphenylsulfone]imide‐1,3‐bis(3,4‐dicarboxyphenoxy)benzene} (PI) and polyaniline (PANI) solutions in N‐methylpyrrolidone. These solutions were used for the preparation of homogeneous and composite membranes. Uniform distribution of PANI particles in the membranes, resulted from interactions between macromolecules, was confirmed by transmission electron microscopy. Membranes based on PI and PI–PANI were tested in pervaporation of binary organic mixtures: methanol/toluene and methanol/cyclohexane and showed a remarkable selectivity with respect to methanol. In both pervaporation processes, selectivity was improved in PANI‐containing membranes. Interactions between membrane polymers and liquid penetrants (methanol, toluene, and cyclohexane) were studied by measurements of surface tension, sorption, and pervaporation parameters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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Indah Prihatiningtyas Yusak Hartanto Maria Sandra Reyes Ballesteros Bart Van der Bruggen 《应用聚合物科学杂志》2021,138(11):50000
A series of cellulose triacetate/Ludox-silica nancomposite pervaporation membranes was successfully prepared via solution casting, aiming to improve the performance of cellulose triacetate membranes for desalination. The fabricated nanocomposite membranes were characterized to study the membrane morphology, chemical composition, mechanical properties, and surface hydrophilicity. Furthermore, the desalination performance was investigated as a function of silica (SiO2) loading (ranging from 1 to 4 wt%) and feed concentration at 30 and 60 g/L of sodium chloride (NaCl). Pervaporation experiments showed that incorporating 4 wt% SiO2 into a cellulose triacetate (CTA) membrane increased the water flux by a factor 2.5 compared with pristine CTA (from 2.2 to 6.1 kg m−2 h−1) for a 30 g/L NaCl feed solution at 70°C, while the salt rejection remained above 99%. The CTA/4 wt% SiO2 membrane was found to have only 21% flux reduction when tested with a 60 g/L NaCl feed solution, without changes in membrane selectivity. This suggests that the developed CTA/Ludox-SiO2 nanocomposite pervaporation membrane is suitable for desalination. 相似文献
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Inmaculada Ortiz Daniel Gorri Clara Casado Ane Urtiaga 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(4):397-405
This work presents a simplified model of wide applicability for the determination of the pervaporation flux through hydrophilic membranes, provided that the adsorption isotherm of the permeating species onto the pervaporation membrane has a linear shape. The model predicts the pervaporation flux as a function of the activity of the penetrant in the liquid phase and the operation temperature. Experimental results obtained working with two polymeric membranes (CMC‐CF‐23 and Pervap 2256) applied to the dehydration of tetrahydrofuran (THF) and to the separation of methanol from alcohol–ether mixtures, respectively, have been satisfactorily correlated and the characterising parameters have been obtained. Furthermore, the model has been also tested against results obtained with two ceramic membranes, Pervap SMS and zeolite NaA, applied to the dehydration of ketonic mixtures and of tetrahydrofuran respectively. Copyright © 2005 Society of Chemical Industry 相似文献
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Mass‐transfer rate enhancement for CO2 separation by ionic liquids: Theoretical study on the mechanism 
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下载免费PDF全文 Wenlong Xie Xiaoyan Ji Xin Feng Xiaohua Lu 《American Institute of Chemical Engineers》2015,61(12):4437-4444
To promote the development of ionic liquid (IL) immobilized sorbents and supported IL membranes (SILMs) for CO2 separation, the kinetics of CO2 absorption/desorption in IL immobilized sorbents was studied using a novel method based on nonequilibrium thermodynamics. It shows that the apparent chemical‐potential‐based mass‐transfer coefficients of CO2 were in three regions with three‐order difference in magnitude for the IL‐film thicknesses in microscale, 100 nm‐scale, and 10 nm‐scale. Using a diffusion‐reaction theory, it is found that by tailoring the IL‐film thickness from microscale to nanoscale, the process was altered from diffusion‐control to reaction‐control, revealing the inherent mechanism for the dramatic rate enhancement. The extension to SILMs shows that the significant improvement of CO2 flux can be obtained theoretically for the membranes with nanoscale IL‐films, which makes it feasible to implement CO2 separation by ILs with low investment cost. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4437–4444, 2015 相似文献
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M. C. Burshe S. B. Sawant V. G. Pangarkar 《Journal of the American Oil Chemists' Society》1999,76(2):209-214
Dehydration of glycerine-water mixtures by pervaporation (PV) was studied with Nafion® (NA), cellulose triacetate (CA), polyimide, carboxylated polyvinyl chloride (CPVC), and polyethersulfone (PES) membranes. PES membrane yielded the highest selectivity (6580) and CPVC membrane yielded the lowest selectivity (1552) at 5% by weight of water in the feed and 30°C. The NA membrane yielded the highest permeation flux (0.2–1.45 kg/m2h) of water over the entire water concentration range. Energy of activation of permeation for water was in the range of 7–15 kJ/mol, being highest for CPVC and lowest for CA. Comparison of PV and vapor liquid equilibrium data showed that the former gave better results, particularly for concentrating glycerine above 90 wt%. 相似文献
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聚氨酯／苯乙烯互穿网络膜的实验研究 总被引：4，自引：0，他引：4
以亲水性强的聚乙二醇（PEG）和甲苯二异氰酸酯（TDI）为原料制备聚氨酯预聚体，而由苯乙烯（ST）和二乙烯苯（DVB）制得交联聚苯乙烯（PS），得到的渗透汽化膜可以进行水／乙醇混合液的分离，通过测试膜的性能，结果显示膜的分离效果较好，运用SEM对膜进行了表征。 相似文献
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《分离科学与技术》2012,47(11):2483-2499
Abstract The selective removal of water from ethanol through pervaporation was demonstrated in a microchannel device using a commercial membrane. Photolithography and dry etching techniques were employed for fabrication of the microseparator with hydraulic diameters of 30 µm to 80 µm. Experiments conducted at 90°C and 2–3 Torr, with Reynolds Numbers ranging from 8 to 91, resulted in an average water and ethanol permeance of 1.2×10?3 and 8×10?5 cm3/cm2 · s · cmHg respectively. A mass transfer analysis involving Sherwood correlations was used to calculate the theoretical boundary layer resistance. The comparison of overall mass transfer coefficient with the boundary layer coefficients suggests that the membrane was the dominant resistance for this system. 相似文献