无机杂化海藻酸钠渗透汽化膜的制备与分离性能对比

为提高海藻酸钠(SA)膜的渗透汽化分离性能,分别采用纳米氧化铝、纳米氧化锆和纳米氧化钛对SA膜进行改性,对比分析了3种不同杂化膜渗透汽化分离性能的差异,并将分离性能较好的杂化膜应用到乙酸与乙醇酯化反应脱水的体系中。系统考察了无机纳米粒子含量对SA膜渗透汽化分离性能的影响,对杂化膜进行了接触角、傅里叶红外(FTIR)、扫描电子显微镜(SEM)、热重/差示扫描量热(TG/DSC)、X射线衍射(XRD)和拉伸强度等表征与分析。结果表明,无机纳米粒子能提高SA膜的热稳定性、机械强度和渗透通量,当无机纳米粒子与SA质量比为0.3时,掺杂TiO_2、ZrO_2和Al_2O_3的杂化膜二碘甲烷的接触角依次升高,同时渗透通量也依次升高。SA-0.3Al_2O_3杂化膜亲水性较好,然而SA-0.3ZrO_2杂化膜分离性能最优,50℃下分离水含量10%的乙醇-水溶液,膜渗透通量达到336 g·m~(-2)·h~(-1),渗透侧水含量99.97%,分离因子29990。酯化反应脱水实验表明,在80℃时,酯化反应脱水实验乙酸转化率均高于无脱水实验乙酸转化率,平衡转化率不断被打破,反应12 h后,转化率由平衡时的79.3%提高到93.9%。     

无机杂化海藻酸钠渗透汽化膜的制备与分离性能对比

为提高海藻酸钠（SA）膜的渗透汽化分离性能,分别采用纳米氧化铝、纳米氧化锆和纳米氧化钛对SA膜进行改性,对比分析了3种不同杂化膜渗透汽化分离性能的差异,并将分离性能较好的杂化膜应用到乙酸与乙醇酯化反应脱水的体系中。系统考察了无机纳米粒子含量对SA膜渗透汽化分离性能的影响,对杂化膜进行了接触角、傅里叶红外（FTIR）、扫描电子显微镜（SEM）、热重/差示扫描量热（TG/DSC）、X射线衍射（XRD）和拉伸强度等表征与分析。结果表明,无机纳米粒子能提高SA膜的热稳定性、机械强度和渗透通量,当无机纳米粒子与SA质量比为0.3时,掺杂TiO₂、ZrO₂和Al₂O₃的杂化膜二碘甲烷的接触角依次升高,同时渗透通量也依次升高。SA-0.3Al₂O₃杂化膜亲水性较好,然而SA-0.3ZrO₂杂化膜分离性能最优,50℃下分离水含量10%的乙醇-水溶液,膜渗透通量达到336 g·m^-2·h^-1,渗透侧水含量99.97%,分离因子29990。酯化反应脱水实验表明,在80℃时,酯化反应脱水实验乙酸转化率均高于无脱水实验乙酸转化率,平衡转化率不断被打破,反应12 h后,转化率由平衡时的79.3%提高到93.9%。     

明胶-聚乙烯醇-硅钨酸渗透蒸发杂化膜分离异丙醇和水

本文通过明胶、聚乙烯醇添加硅钨酸制备成杂化膜分离异丙醇和水混合物,考察了硅钨酸含量、原料液浓度及温度对异丙醇/水分离性能的影响。结果表明硅钨酸的加入能有效提高杂化膜的分离效果,随着硅钨酸含量的增加,杂化膜的对水的选择性先增加后下降,在6wt%时有最好的选择性,同时硅钨酸的增加可提高膜通量。原料液浓度的增大会提高膜的分离因子,降低膜的通量。原料液温度的增加会降低膜的分离因子,提高膜的通量。本研究所制备的杂化膜呈现出良好的渗透蒸发分离性能,当进料异丙醇浓度为90 wt%,温度为30 ℃时,膜的分离因子和通量分别为303和451 g/h·m~2。     

聚二甲基硅氧烷-聚丙烯酸甲酯半互穿聚合物网络结构渗透汽化膜的制备及性能

为了提高聚二甲基硅氧烷(PDMS)膜的渗透汽化性能,采用一锅法制备PDMS-PMA半互穿聚合物网络结构(semi-IPN)渗透汽化膜,通过红外光谱和扫描电镜对其进行表征,并探究其溶胀性能和渗透汽化性能。结果表明,IPN结构的形成明显提高了PDMS膜的渗透汽化性能;在原料液温度为70℃、PMA含量为10%时,semi-IPN渗透汽化膜的分离因子为42.0、总通量为923 g·m~(-2)·h~(-1)。     

聚乙烯醇/超支化聚酯交联渗透汽化膜的制备及其溶解扩散性能分析

将超支化聚酯（HBPE）与聚乙烯醇（PVA）共混交联制备了PVA/HBPE交联渗透汽化膜,研究了PVA/HBPE交联膜内的溶解扩散及渗透汽化性能。结果表明,随着温度的增加,水在交联膜内的渗透系数（Pwater）增加,且变化趋势与纯水通量一致,在55 ℃时达到最大值71.952 g/m2·h;随着HBPE含量的增加,渗透系数Pwater及纯水通量呈现增加的趋势,当HBPE含量为40 %时,纯水通量达到最大值185.726 g/m2·h。     

ZIF-67/PEBA杂化膜分离水中乙酸乙酯

为了提升从水溶液中回收乙酸乙酯的渗透汽化分离效率,将疏水ZIF-67颗粒填充到聚醚共聚酰胺(PEBA)中,制备得到ZIF-67/PEBA杂化膜。通过扫描电镜(SEM)、能谱(EDS)、接触角测量、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、热重(TGA)和溶胀度测试等手段对ZIF-67和杂化膜的物理化学性质进行表征,通过渗透汽化实验考察ZIF-67质量分数、进料质量分数和温度对膜分离性能的影响。结果表明ZIF-67与PEBA基质之间为物理共混,杂化膜疏水性增强。随着ZIF-67质量分数的增加,总渗透通量先降低后升高,分离因子先升高后降低,当ZIF-67质量分数为5%时分离因子最高;随着进料质量分数或温度增加,总渗透通量和分离因子均增加,最大总渗透通量为2299g·m~(-2)·h~(-1),最大分离因子为122。研究为渗透汽化技术工业化应用提供了必要的基础数据和理论依据。     

聚氨酯膜的制备及渗透汽化分离水中苯酚性能研究

研究通过两步反应法制备端羟基聚丁二烯基聚氨酯（HTPB-PU）渗透汽化膜,采用红外、热分析、扫描电镜等手段对其结构与性能进行了表征,研究了该膜从水中分离苯酚的渗透汽化性能。结果发现,该膜表现出良好的优先透过苯酚的分离性能。以0.5%苯酚水溶液作为料液,随着操作温度从60℃增加到80℃,渗透通量增加而分离因子下降,在60℃时,分离因子与渗透通量可分别达到23.80与2.85 kg.μm.m-2.h-1。     

响应面优化法在PDMS/PVDF膜制膜条件优化中的应用

用响应面优化法优化了乙烯基封端PDMS/PVDF渗透汽化透醇膜的制膜条件,研究了硅橡胶浓度、B/A质量比、交联温度和交联时间对膜性能的影响,拟合了分离因子、渗透通量与四因素之间的回归方程,并用方差分析法考察了四因素的主效应、二次效应以及相互作用效应对复合膜的分离因子与渗透通量的影响。研究发现,硅橡胶浓度对膜的分离因子与渗透通量的影响最为显著,交联时间对分离因子几乎没有影响。通过对回归方程的优化分析得知,在料液乙醇浓度为10%(wt),操作温度40℃条件下,当硅橡胶浓度为93%(wt),B/A质量比为0.08,交联温度为100℃,交联时间为13.83 h时,膜的综合分离性能达到最佳,此时分离因子与渗透通量预测值分别为9.47、77.57 g(m2 h)1,渗透侧乙醇浓度达到51.3%(wt)。回归方程的验证实验结果表明,回归方程的估计值与实验值较为吻合,可用于乙烯基封端的PDMS/PVDF复合膜的渗透汽化性能的预测与优化。     

PVA/PEG/TEOS杂化膜制备及性能研究

以聚乙烯醇(PVA)与聚乙二醇(PEG)共混,并与正硅酸乙酯(TEOS)进行交联反应制备杂化膜。FTIR证实杂化溶胶液发生交联反应形成共价键Si—O—C,WXRD观察表明加入TEOS改变了膜结晶度,加入PEG提高了PVA膜对乙醇/水溶液的渗透通量,但分离因子下降,随着TEOS的加入,膜的分离因子提高。在TEOS质量分数为10%时,杂化膜的分离因子达到最大。提高退火温度可以提高膜的分离因子,但通量下降。在100℃下退火12 h的杂化膜对乙醇质量分数为85%的乙醇/水溶液的分离性能最佳。     

渗透汽化-结晶耦合分离稀溶液中的香兰素

以聚醚嵌段共聚酰胺（PEBA2533）为膜材料,采用干法相转化法制备性能优异的高分子膜,用于渗透汽化-结晶耦合（PVCC）分离系统中回收稀水溶液中的香兰素。采用扫描电子显微镜（SEM）对PEBA2533膜的形貌进行表征。考察原料液浓度、温度对膜渗透汽化性能的影响。结果表明：随着溶液浓度的增加,PEBA2533膜溶胀性能增加,说明PEBA2533能够优先吸附香兰素;随原料液浓度增加,香兰素渗透通量增加,分离因子略微下降;原料液温度增加,香兰素渗透通量和分离因子都增加;并通过Arrhenius方程计算得到香兰素比水对温度更加敏感。PVCC系统中控制一级冷凝器温度为2℃时,一级冷凝器中结晶态香兰素通量为39.52 g·m^-2·h^-1,纯度在99%以上。     

Separation of methanol from methanol/water mixtures with pervaporation hybrid membranes

A series of pervaporation (PV) hybrid membranes were prepared via the crosslinking of poly(vinyl alcohol) with formaldehyde solution with N‐3‐(trimethoxysilyl) propyl ethylenediamine (TMSPEDA) as a hybrid precursor of the sol–gel process. Both the thermal stability and separation performances of the prepared hybrid membranes were investigated. Thermogravimetric analysis showed that the thermal degradation temperature of the hybrid membranes was beyond 250°C. Differential scanning calorimetry indicated that both the glass‐transition temperature and the crystallization temperature increased with elevated TMSPEDA contents in the hybrid membranes. PV experiments demonstrated that for membranes A–D, both the permeation flux and separation factor indicated the same trade‐off effect. Moreover, it was found that for individual membranes, the permeation flux increased as the feed temperature was increased. Meanwhile, the separation factor revealed an change trend opposite to that of the permeation flux. Furthermore, proper addition of TMSPEDA in the hybrid membrane was found to reduce the permeation activation energy. On the basis of these findings, we deduced that these hybrid membranes have potential applications in the separation of methanol/water mixtures. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

聚乙烯醇-二氧化硅/聚丙烯腈杂化复合膜渗透蒸发分离己内酰胺/水溶液

制备了以聚乙烯醇(PVA)填充纳米SiO2改性膜为活性层,聚丙烯腈(PAN)超滤膜为底膜的PVA-SiO2/PAN杂化复合膜,并用于己内酰胺(CPL)脱水。用FTIR,SEM,XRD,TGA分别对膜进行了表征,并考察了膜中纳米SiO2粒子的质量分数、进料组分质量分数和温度对复合膜分离性能的影响。结果表明,引入纳米SiO2后,杂化膜的热稳定性明显提高。当膜中纳米SiO2质量分数为1.0%时,复合膜渗透蒸发分离性能最佳。60℃下此复合膜用于分离质量分数为40%的CPL溶液时,其总通量和分离因子分别达到2 177 g/(m2.h)和349。     

新型聚乙烯醇/硅系杂化膜的制备及渗透性能

采用溶胶-凝胶法制备了聚乙烯醇（PVA）/γ-氨丙基三乙氧基硅氧烷（APTEOS）有机/无机杂化膜。用FTIR和XRD对杂化膜进行了表征。测定了膜在乙醇/水溶液中的溶胀行为。考察了杂化膜对85%（质量）的乙醇/水溶液的渗透蒸发分离性能。加入APTEOS降低了PVA的结晶度,有效控制了膜的溶胀,呈现出优良的分离性能。随着APTEOS含量的增加,杂化膜的选择性急剧增加,在5.0%（质量）时达到最大值;同时膜的渗透通量迅速增加。解决了PVA膜trade-off效应。     

来瓦希尔骨架材料MIL-53(Al)填充PEBA膜渗透汽化分离水中苯胺

将来瓦希尔骨架材料MIL-53(Al)引入到聚醚共聚酰胺（PEBA-2533）高分子相中制备了不同填充量的PEBA/MIL-53(Al)杂化膜并用于渗透汽化分离水中微量苯胺。X-射线衍射结果证实MIL-53(Al)被成功合成。扫描电镜和激光粒度分析结果表明所制备MIL-53(Al)颗粒粒径在纳米尺度范围内。采用扫描电镜、红外光谱、X-射线衍射、差示扫描量热和水接触角对杂化膜进行了表征,并考察了杂化膜的溶胀行为和分离性能。结果表明,所得杂化膜的热稳定性较好。当MIL-53(Al)质量分数小于20%时,MIL-53(Al)在高分子相中分散均匀,继续增大填充量出现团聚现象。杂化膜的结晶度随MIL-53(Al)填充量的增加而降低。MIL-53(Al)的引入增强了杂化膜的疏水性和溶胀度。在料液温度为60℃、膜下游压力400Pa、料液苯胺质量分数为3.6%时,MIL-53(Al)质量分数为20%的杂化膜（M-20）综合分离性能最优,渗透通量达到2.15kg/(m²·h),分离因子为264。12天的稳定性测试结果表明所得杂化膜分离性能无显著变化,能够满足渗透汽化应用要求。     

Synthesis and characterization of hybrid membranes using poly(vinyl alcohol) and tetraethylorthosilicate for the pervaporation separation of water–isopropanol mixtures

Hybrid membranes were prepared using poly(vinyl alcohol) (PVA) and tetraethylorthosilicate (TEOS) via hydrolysis and cocondensation reaction for the pervaporation separation of water‐isopropanol mixtures. The resulting membranes were characterized by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and differential scanning calorimetry. The glass transition temperature of these membranes varied from 100 to 120°C with increasing TEOS content. Effects of crosslinking density and feed compositions on the pervaporation performances of the membranes were studied. The membrane containing 1.5:1 mass ratio of TEOS to PVA gave the highest separation selectivity of 900 at 30°C for 10 mass % of water in the feed mixture. It was found that the separation selectivity and permeation flux data are strongly dependent on the water composition of the feed and operating temperature. However, the membrane with the highest crosslinking density showed unusual pervaporation properties. The overall activation energy values were calculated using the Arrhenius‐type equation. The activation energy values for the permeation and diffusion varied from 49.18 to 64.96 and 55.13 to 67.31 kJ/mol, respectively. Pervaporation data have also been explained on the basis of thermodynamic quantities. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1304–1315, 2004     

Pervaporation characteristics and structure of poly(vinyl alcohol)/poly(ethylene glycol)/tetraethoxysilane hybrid membranes

Poly(vinyl alcohol) (PVA) blended with poly(ethylene glycol) (PEG) was crosslinked with tetraethoxysilane (TEOS) to prepare organic–inorganic PVA/PEG/TEOS hybrid membranes. The membranes were then used for the dehydration of ethanol by pervaporation (PV). The physicochemical structure of the hybrid membranes was studied with Fourier transform infrared spectra (FT‐IR), wide‐angle X‐ray diffraction WXRD, and scanning electron microscopy (SEM). PVA and PEG were crosslinked with TEOS, and the crosslinking density increased with increases in the TEOS content, annealing temperature, and time. The water permselectivity of the hybrid membranes increased with increasing annealing temperature or time; however, the permeation fluxes decreased at the same time. SEM pictures showed that phase separation took place in the hybrid membranes when the TEOS content was greater than 15 wt %. The water permselectivity increased with the addition of TEOS and reached the maximum at 10 wt % TEOS. The water permselectivity decreased, whereas the permeation flux increased, with an increase in the feed water content or feed temperature. The hybrid membrane that was annealed at 130°C for 12 h exhibited high permselectivity with a separation factor of 300 and a permeation flux of 0.046 kg m^?2 h^?1 in PV of 15 wt % water in ethanol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Perfluorosulfonic acid—Tetraethoxysilane/polyacrylonitrile (PFSA‐TEOS/PAN) hollow fiber composite membranes prepared for pervaporation dehydration of ethyl acetate–water solutions

Preparation of organic‐inorganic composite membranes and their pervaporation (PV) permeation and separation characteristics for the aqueous solution of ethyl acetate were described. Polyacrylonitrile (PAN) hollow fiber ultrafiltration membrane as support membrane, the mixtures of perfluorosulfonic acid (PFSA) and tetraethoxysilane (TEOS) by the sol‐gel reaction as the coating solution, the PFSA‐TEOS/PAN hollow fiber composite membranes by the different annealing conditions were prepared. The swelling of PFSA in ethyl acetate aqueous solutions was inhibited with addition of TEOS. The PFSA‐TEOS/PAN composite membranes containing up to 30 wt % TEOS in coating solution exhibited high selectivity towards water, then the selectivity decreased and permeation flux increased with increasing the TEOS concentration more than 30 wt %. When the PFSA‐TEOS/PAN composite membranes were annealed, the separation factor increased with increasing annealing temperature and time. Higher annealing temperature and longer annealing time promoted the crosslinking reaction between PFSA and TEOS in PFSA‐TEOS/PAN composite membranes, leading to the enhanced selectivity towards water. For the PFSA/PAN and PFSA‐TEOS/PAN composite membrane with 5 and 30 wt % TEOS annealed at 90°C for 12 h, their PV performance of aqueous solution 98 wt % ethyl acetate were as follows: the separation factors were 30.8, 254 and 496, while their permeation flux were 1430, 513 and 205 g/m² h at 40°C, respectively. In addition, the PV performance of PFSA‐TEOS/PAN composite membranes was investigated at different feed solution temperature and concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of cross‐linking time on the thermal and mechanical properties and pervaporation performance of poly(vinyl alcohol) membrane cross‐linked with fumaric acid used for dehydration of isopropanol

Cross‐linked poly (vinyl alcohol) membranes were prepared using fumaric acid as the cross‐linking agent and were used for the pervaporation separation of water/isopropanol mixtures. Cross‐linking process was carried out at 150°C at three different times of 10, 30, and 60 min. The membranes were characterized by different known methods of FT‐IR, TGA, XRD as well as tensile test. The effects of cross‐linking time on the thermal and mechanical properties of the membranes and also their pervaporation performance were investigated. Formation of more ester groups by increasing the cross‐linking time was confirmed by the FT‐IR results. TGA analyses showed that thermal stability of the membranes is improved by prolonging the duration of cross‐linking process. This was due to the formation of more compact structure in the membranes. The XRD results revealed that the crystalline regions of the membranes were relatively diminished with an increase in the cross‐linking time. No specific trend was observed for the variation of tensile strength at break with the cross‐linking time. The PVA membrane cross‐linked for 60 min showed high selectivity of 1492 for water permeation for the feed mixture containing 10 wt % water. The temperature dependency of the permeation flux was investigated using Arrhenius relationship, and the activation energy values were calculated for total permeation (E_p), water (E_pw), and IPA (E_pIPA) fluxes. Lower value of E_pw in comparison with E_pIPA supported excellent dehydration performance of the cross‐linked membranes. Despite large increase in activation energy of water with prolonged cross‐linking time, the selectivity was improved. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2013     

Pervaporation separation of binary and ternary mixtures with polydimethylsiloxane membranes

This study dealt with the separation of binary water–phenol and water–methanol mixtures and ternary water–phenol–methanol mixtures by pervaporation (PV) with polydimethylsiloxane (PDMS) membranes. The effects of the operating conditions (feed temperature, feed concentration, and feed flow rate) on the separation performance for binary mixtures were investigated. An increase in temperature or concentration increased the total permeation flux and decreased the organic separation factor. In other words, an increase in the temperature or feed organic concentration increased the water flux more significantly than the organic compound flux, which resulted in a separation factor reduction. Also, an increase in the feed flow rate increased the total flux and separation factor because the boundary layer effects diminished. The vapor–liquid equilibrium separation factor (α_VLE) and pervaporation separation factor (α_PV) values for the PDMS membrane were calculated, and this showed that α_PV for the water–phenol mixture was greater than α_VLE. This means that the membrane was highly efficient for the PV separation of phenol from dilute aqueous solutions relative to the separation of methanol. This was due to the fact that phenol has a higher solubility parameter than methanol in silicone membranes. To study the effect of a third component on membrane performance, PV experiments were also carried out with water–phenol–methanol mixtures. The results for total permeation flux and the phenol separation factor for PDMS membranes in contact with water–phenol–methanol ternary mixtures are similar to those in contact with water–phenol binary mixtures. The phenol separation factor of the membrane in contact with the ternary mixture was slightly lower than that in contact with the binary mixture. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008