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771.
制备了不同活性炭(AC)填充量的AC-PEG/PVDF杂化膜,并对其形貌与结构进行了相应的表征。以噻吩/正庚烷混合物作为模拟汽油体系,研究了所制备AC-PEG杂化膜的渗透汽化脱硫性能。研究表明,填充活性炭后,膜的脱硫性能明显提高。当活性炭填充量为5%,温度为85℃时,与未填充的PEG膜相比,AC-PEG/PVDF杂化膜的渗透通量由0.43 kg·(m2·h)-1提高至1.14 kg·(m2·h)-1,富硫因子由7.29提高至9.47。 相似文献
772.
采用二次生长法,在α-Al2O3载体上制备丝光(MOR)沸石膜,并通过改变合成液体系以及合成过程,制备出优质MOR沸石膜。通过X射线衍射、扫描电子显微镜和能谱研究了加氟前后制备的沸石膜微观结构及其n(Si)/n(Al)摩尔比的变化,并用异丙醇/水体系评价膜的渗透汽化性能。结果表明:改变合成液中的n(F–)/n(Al2O3)比,对制备的沸石膜表面的沸石晶体粒度、结晶度、膜厚以及膜的n(Si)/n(Al)比有影响。当n(F–)/n(Al2O3)=2.0时制备的沸石膜厚度仅约为8μm,n(Si)/n(Al)为8.5;优化合成过程后,制备的膜厚度进一步降低,约为6μm,且其渗透通量和分离因子也分别由无氟体系的0.122 kg/(m2·h)和884提升到优化后的0.219 kg/(m2·h)和2005。 相似文献
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775.
Polyacrylamide‐grafted sodium alginate (PAAm‐g‐Na‐Alg) copolymeric membranes have been prepared, characterized, and used in the pervaporation separation of 10–80 mass % water‐containing tetrahydrofuran mixtures. Totally three membranes were prepared: (1) neat Na‐Alg with 10 mass % of polyethylene glycol (PEG) and 5 mass % of polyvinyl alcohol (PVA), (2) 46 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA, and (3) 93 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA. Using the transport data, important parameters like permeation flux, selectivity, pervaporation separation index, swelling index, and diffusion coefficient have been calculated at 30°C. Diffusion coefficients were also calculated from sorption gravimetric data of water–tetrahydrofuran mixtures using Fick's equation. Arrhenius activation parameters for the transport processes were calculated for 10 mass % of water in the feed mixture using flux and diffusion data obtained at 30, 35, and 40°C. The separation selectivity of the membranes ranged between 216 and 591. The highest permeation flux of 0.677 kg/m2 h was observed for 93% grafted membrane at 80 mass % of water in the feed mixture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 272–281, 2002 相似文献
776.
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
777.
Pervaporation(PV),as an environmental friendly and energy-saving separation technology,has been received increasing attention in recent years.This article reviews the preparation and application of macroporous ceramic-supported polymer composite pervaporation membranes.The separation materials of polymer/ceramic composite membranes presented here include hydrophobic polydimethylsiloxane(PDMS) and hydrophilic poly(vinyl alcohol)(PVA),chitosan(CS) and polyelectrolytes.The effects of ceramic support treatment,polymer solution properties,interfacial adhesion and incorporating or blending modification on the membrane structure and PV performance are discussed.Two in-situ characterization methods developed for polymer/ceramic composite membranes are also covered in the discussion.The applications of these composite membranes in pervaporation process are summarized as well,which contain the bio-fuels recovery,gasoline desulfuration and PV coupled proc-ess using PDMS/ceramic composite membrane,and dehydration of alcohols and esters using ceramic-supported PVA or PVA-CS composite membrane.Finally,a brief conclusion remark on polymer/ceramic composite mem-branes is given and possible future research is outlined. 相似文献
778.
Toshinori Tsuru Akifumi Sasaki Masakoto Kanezashi Tomohisa Yoshioka 《American Institute of Chemical Engineers》2011,57(8):2079-2089
Porous silica membranes with different pore sizes (average pore size: 0.3–1.2 nm) and surface chemistry were prepared from SiO2, steam‐treated SiO2, SiO2? ZrO2, and SiO2? TiO2 by sol‐gel processing, and were applied to the pervaporation (PV) separation of methanol (MeOH) /dimethyl carbonate (DMC) mixtures at 50°C. Although SiO2? ZrO2 membranes demonstrated a separation factor of <10, the SiO2 porous membranes had an increased separation factor from 10–160. Silica membranes with an average pore size of 0.3 nm showed the highest permselectivity of methanol with a separation factor of 140 and a methanol flux of 180 mol/(m2h) for MeOH 50 mol% at 50°C. To characterize the surface property of SiO2 membranes, SiO2 powdered samples were used for an adsorption experiment of vapor (MeOH, DMC) in single and mixed systems, revealing increased MeOH selective adsorption for SiO2 powders with hydrophilic and small pores, which was consistent with PV performance. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
779.
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
780.
《分离科学与技术》2012,47(5):716-727
In this study, the morphological and separation characteristics of PVA membranes incorporated with functionalized CNTs are reported. CNTs was extensively characterized using TGA, FESEM, and TEM. The physicochemical properties of PVA-CNTs membranes were characterized using FESEM, tensile test, DSC, and XRD. DSC measurements showed an increase in melting and glass transition temperature, implying enhancement of polymer chains compacting. XRD analysis confirmed the results of DSC and showed that CNTs can promote crystallinity of the PVA membranes. In addition, tensile measurements revealed that incorporating CNTs into the PVA membranes improves their mechanical properties. The synthesized nanocomposite membranes were then evaluated in pervaporation (PV) dehydration of isopropanol (IPA). The separation results showed that incorporating CNTs into the PVA membranes significantly increases water selectivity of the PVA membranes. This can be attributed to the fact that incorporating CNTs compacts and rigidifies PVA matrix and decreases its free volume. Furthermore, permeation of water molecules through the nanocomposite membranes decrease as a result of the polymer chains rigidification. Effects of feed composition and temperature on PVA-CNTs nanocomposite membranes were investigated. Besides, effects of CNTs content on permeation properties and activation energies of PVA membranes were evaluated. 相似文献