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81.
采用市售廉价大孔α-Al2O3管作为基质材料,通过热浸渍法在管外表面涂敷晶种,随后在无模板剂体系下,利用新型的间歇式水热合成法制备丝光沸石膜。对比了传统加热和间歇式加热对丝光沸石膜形貌、结构及渗透蒸发异丙醇脱水分离性能的差异。考察了合成液中Na2O/SiO2、SiO2/Al2O3和NaF/SiO2物质的量之比在间歇式水热合成下对丝光沸石膜的影响。研究结果表明,当合成液中Na2O/SiO2、SiO2/Al2O3和NaF/SiO2物质的量之比分别为0.24、16.7和0.25时,制备的丝光沸石膜渗透蒸发异丙醇脱水分离性能最佳,在75℃下,对异丙醇/水(9∶1,w/w)的渗透通量达5.60 kg·m-2·h-1,水对异丙醇的分离因数大于10 000。 相似文献
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M. Eva Moreno Riansares Muñoz Concepción Perez-Conde Carmen Cámara 《International journal of environmental analytical chemistry》2013,93(3-4):413-426
Abstract This paper reports for the first time a suitable way to determine methylated selenium compounds using the new approach of pervaporation coupled to atomic fluorescence spectrcmetry (PV-AFS). The method developed allows direct extraction, separation, preconcentration and determination of dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) from slurry samples. Under the optimum conditions, the detection limits (LODs) were found to be 0.66 ng and 0.39 ng for DMSe and DMDSe, respectively, the precision being about 6–9 % for 10 ng mL as selenium concentration. The linearity ranges were from the LOD to 0.7 μg mL?1 for DMSe and from the LOD to 0.4 μg mL?1 for DMDSe (as Se). The pervaporation efficiencies were 55 ± 1 % and 85 ± 5 % for DMSe and DMDSe, respectively. The proposed method was successfully applied to determine methylated selenium species in sewage sludge, garlic and oyster samples. The concentrations found were from 0.07 to 1.42 μg g?1. As no certified reference materials are available for these analytes, validation was carried out by recovery studies in these matrices, and the results showed that the proposed method performed satisfactorily. 相似文献
85.
在水热晶种法基础上采用两步变温晶化以高水硅比(nH2O/nSiO2)稀溶液配方为合成液,研制用于渗透汽化(PV)乙酸脱水的丝光沸石膜(MOR膜),考察了变温晶化各段时间、水硅比与氟离子对 MOR膜的形貌与分离性能的影响规律。结果表明:高温段晶化时间、水硅比与氟离子对MOR膜的形貌、结晶度和膜层厚度产生显著影响,并影响MOR膜渗透气化分离性能;在高温段(150 ℃)和低温段(120 ℃)的晶化时间分别为 18和 6 h,在水硅比为 60且含氟离子体系中所制备的 MOR膜的性能最佳,其对质量分数50%的乙酸水溶液的渗透通量和分离系数分别为1.45 kg·m-2·h-1和1 008。 相似文献
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Two kinds of polyimides containing fluorine were synthesized based on dianhydride of 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and diamines including 2,2‐bis[4‐(4‐aminophenoxy)phenyl] hexafluoropropane (BDAF) and 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane (BAPP) using solution condensation and following chemical imidization. The structures of 6FDA‐BDAF and 6FDA‐BAPP were characterized by FT‐IR, NMR, and XRD. Their glass transition temperatures characterized by DSC were in the range of 235–251°C, and the initial decomposition temperatures determined by TGA were over 540°C. The membranes of polyimide thus obtained were employed in pervaporation separation of aromatic/aliphatic mixtures. 6FDA‐BDAF membranes obtained better separation performances than 6FDA‐BAPP and had a flux of 0.66 kg · µm/m2 · h and separation factor of 6.49 for toluene/n‐heptane (20/80 wt.%) at 80°C. The effects of the fluorine group on polyimides properties and separation performances were investigated. 相似文献
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分别使用十二烷基三甲氧基硅烷(DMS)和硬脂酸(STA)对α-Al2O3载体上二次生长合成的silicalite-1膜进行修饰,提高其表面疏水性。红外光谱和接触角测试结果表明,改性剂以化学键的形式结合于分子筛膜表面,膜表面由亲水变为疏水。表面改性的最佳预处理温度为150℃,改性剂的最佳质量分数为10%。进一步研究了膜表面润湿特性和热稳定性,其中DMS改性后的分子筛膜在空气中经250℃高温处理后仍保持疏水性不变。在乙醇/水分离应用中,高温脱除模板剂后缺陷的孔径分布在1~5nm,表面改性后乙醇分离因子较改性前提高5倍,最高可达21.6。 相似文献
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A Graphene Oxide Membrane with Highly Selective Molecular Separation of Aqueous Organic Solution 下载免费PDF全文
Kang Huang Dr. Gongping Liu Yueyun Lou Ziye Dong Jie Shen Prof. Wanqin Jin 《Angewandte Chemie (International ed. in English)》2014,53(27):6929-6932
A graphene oxide (GO) membrane is supported on a ceramic hollow fiber prepared by a vacuum suction method. This GO membrane exhibited excellent water permeation for dimethyl carbonate/water mixtures through a pervaporation process. At 25 °C and 2.6 wt % feed water content, the permeate water content reached 95.2 wt % with a high permeation flux (1702 g m?2 h?1). 相似文献