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新型硅-氟渗透汽化膜的制备及醇/水分离性能研究
论文作者:童鞋论文网  论文来源:www.txlunwenw.com  发布时间:2019/10/26 13:38:50  

摘要:近年来,由于化石能源的缺乏和环境污染等问题日益严重,乙醇作为可再生能源得到了越来越多的关注。传统方法分离回收乙醇具有耗能大、操作复杂、污染环境等缺点,而基于膜分离的渗透汽化技术具有环境友好,操作简单、能耗低等优点。因此,采用渗透汽化技术进行醇/水分离受到了广泛的关注。渗透汽化技术的核心是高性能渗透汽化膜。本文通过溶胶-凝胶法制备出一系列具有不同结构的新型硅-氟杂化膜,并应用于渗透汽化醇/水分离,系统考察了膜结构和渗透汽化操作条件对醇/水分离性能的影响。

以氟基三乙氧基硅烷(TEFS)为硅源前驱体,采用多孔α-Al2O3陶瓷膜为支撑体,SiO2-ZrO2为过度层,制备硅-氟杂化膜(TEFS),并将其应用于渗透汽化乙醇/水分离。通过动态光散射(DLS)、傅里叶红外光谱(FT-IR)、热重分析(TGA)、智能重量分析(IGA)和场发射扫描电镜(FE-SEM)对膜结构进行表征。考察了TEFS材料在分离体系中的稳定性,以及进料浓度、渗透侧压力、进料温度等操作条件对膜渗透汽化分离性能的影响。结果表明,随着进料浓度的增加,膜的渗透通量增加,分离因子减小;随着渗透侧压力的增加,膜的渗透通量降低,分离因子增加;随着进料温度的增加,膜的渗透通量增加,分离因子减小。在50 °C,浓度为5 wt%的乙醇-水溶液中,该膜的渗透通量高达17.2 kg m-2 h-1。

以TEFS为硅源前驱体,通过四乙氧基硅烷(TEOS)与TEFS交联共聚调控硅网络结构的孔道大小,制备一系列硅-氟杂化膜(TEOS/TEFS)。通过DLS、FT-IR、TGA、FE-SEM和水吸附对膜结构进行表征。将制备的TEOS/TEFS膜应用于渗透汽化脱醇,考察TEOS含量等因素对TEOS/TEFS膜渗透汽化性能的影响。60 mol% TEOS共聚的TEOS/TEFS-6膜的分离因子相比于TEFS膜提高了约2倍。另外,考察了煅烧温度对膜分离性能的影响,随着煅烧温度升高,膜的致密化程度增加,膜的渗透通量降低,分离因子增加。

用TEFS作为硅源前驱体,通过甲基三乙氧基硅烷(MTES)与TEFS共聚优化硅网络结构和表面性质,制备出的硅-氟杂化膜对小分子醇表现出优异的渗透选择性。通过FT-IR、TGA、智能重量分析仪等,研究膜的化学结构,热稳定性、孔道大小和硅网络表面性质。系统研究了渗透汽化操作条件(进料温度、渗透侧压力和进料浓度)对MTES/TEFS膜醇/水分离性能的影响。此外,在连续工作100 h的渗透汽化测试中,该膜的渗透通量和分离因子基本保持恒定,表明此类硅-氟杂化膜具有良好的结构稳定性。

In recent years, due to the lack of fossilenergy and environmental pollution, ethanol as a renewable energy has attractedmuch attention. The traditional methods for the recovery of ethanol typicallyhas the disadvantages of high energy consumption, complicated operation andenvironmental pollution, while membrane based pervaporation has the advantagesof friendly environmental, simple operation and low energy consumption.Therefore, the application of pervaporation separation of alcohol/water hasattracted extensive attention. The core of pervaporation technology is thehigh-performance pervaporation membrane. In this paper, a series of newsilica-fluorine hybrid membranes with different structures were prepared by thesol-gel method and applied to pervaporation separation of alcohol/water. Theeffects of membrane structure and operating conditions on pervaporationperformance were investigated systematically.

Triethoxyfluorosilane (TEFS) was used as anovel silica precursor. Porous α-Al2O3 ceramic membrane was used as a supportwith SiO2-ZrO2 as an intermediate layer to prepare fluorine-containing silicahybrid membranes. The prepared membranes were applied to pervaporationseparation of alcohol/water mixtures. The membrane structure was characterizedby dynamic light scattering (DLS), fourier infrared spectroscopy (FT-IR),thermogravimetric analysis (TGA), intelligent gravimetric analysis (IGA) andfield emission scanning electron microscopy (FE-SEM). The stability of TEFSmaterials in the system and the influence of operating conditions includingfeed concentration, permeate pressure and feed temperature on the pervaporationperformance for separation of alcohol/water were investigated. The resultsshowed that the permeation flux increasesds and the separation factor decreasedwith an increase in feed concentration. With the increase of the permeationpressure, the permeation flux decreased and the separation factor increased.With the increase of feed temperature, the permeation flux of the membraneincreased and the separation factor decreased. At 50 °C, the permeation flux ofthe membrane reached to 17.2 kg m-2 h-1 in an ethanol/water solution with anethanol concentration of 5 wt%.

The TEFS was used as a silica precursor. Aseries of silica-fluorine hybrid membranes were prepared by cross-linkingcopolymerization of tetraethoxysilane (TEOS) and TEFS to control the pore sizeof network structure. The membrane structure was characterized by DLS, FT-IR,TGA, FE-SEM and water adsorption. The prepared TEOS/TEFS membranes were appliedto pervaporation dealcoholization, and the effects of TEOS content andoperational variables on pervaporation performance of the membrane wereinvestigated. The silica-fluorine hybrid membrane TEOS/TEFS-6 which contained60 mol% TEOS showed approximately 2 times higher separation factor than that ofthe unmodified TEFS membrane. Furthermore, the influence of calcinationtemperature on membrane performance was studied. With an increase in calciningtemperature, the silica networks became denser, leading to a decrease inpermeation flux, and an increase in separation factor.

Alcohol preferentially permeatedsilica-fluorine hybrid membranes were prepared by copolymerization ofmethyltriethoxysilane (MTES) and TEFS to control the network structure andsurface properties. These membranes exhibit excellent permselectivity for smallalcohol molecule. The chemical structure, thermal stability, pore structure andwater/ethanol adsorption properties of the membrane were investigated by FT-IR,TGA, intelligent weight analyzer, etc. The effects of operating conditionsincluding feed temperature, permeate pressure and feed concentration onpervaporation performance of the MTES/TEFS membrane were systematicallyinvestigated.

关键词:硅膜;渗透汽化;醇/水分离;氟基三乙氧基硅烷

silica membrane; pervaporation;alcohol/water separation; triethoxyfluorosilane

上一篇:聚偏氟乙烯/凹凸棒石复合超滤膜结构调控及其性能     下一篇:档案纸张损毁机理探讨
 
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