无机盐对聚二甲基硅氧烷/陶瓷复合膜渗透汽化性能的影响

将渗透汽化应用于醇/水体系的分离,具有诸多显著的优势。然而,目前的研究大都基于二元体系,而实际的应用体系是多元的,还包含少量无机盐和糖类等,它们的存在对膜的性能具有一定的影响。本文研究了NaCl、KCl和MgCl2 3种无机盐的加入对聚二甲基硅氧烷 （PDMS）/陶瓷复合膜渗透汽化性能的影响。结果表明,在313 K,无机盐的加入使复合膜的分离因子和通量均有所提高。其中二价盐MgCl2对渗透汽化性能的影响最为显著,分离因子最大提高到醇/水体系的2.8倍。而一价盐NaCl和KCl的加入,使分离因子分别提高为醇/水体系的2.5倍和2.4倍。同时借助于Setschenow扩展方程计算了乙醇活度,对实验结果进行了初步的解释。     

聚二甲基硅氧烷/聚醚砜复合膜渗透汽化分离水中乙酸的性能研究

制备了聚二甲基硅氧烷/聚醚砜(PDMS/PES)复合膜,用于乙酸/水体系的渗透汽化分离。研究了料液质量浓度、温度、流速及下游侧压力对渗透汽化分离性能的影响。实验结果表明,随着料液中乙酸质量浓度的增大,渗透通量增加,而分离因子呈先增大后减小的趋势;随着料液温度的升高,渗透通量增大而分离因子减小;随着料液流速的增大,渗透通量增大而分离因子减小,当达到湍流状态后,两者的变化趋势不明显;随着下游侧压力的增大,渗透通量和分离因子均减小,为获得较好的分离效果应使透过侧保持尽可能高的真空度。     

聚二甲基硅氧烷的改性技术及其渗透汽化性能的影响因素

介绍了聚二甲基硅氧烷(PDMS)的改性技术,总结了不同改性方法在渗透汽化中的应用,分析了影响PDMs膜渗透汽化性能的影响因素,指出了PDMs膜存在的问题及其发展方向.     

聚二甲基硅氧烷渗透汽化膜改性技术研究进展

聚二甲基硅氧烷膜改性是渗透汽化领域研究的一个热点问题.综述了共聚、填充、交联、共混和表面改性等聚二甲基硅氧烷(PDMS)渗透汽化膜改性方法及其研究进展,并且展望了渗透汽化膜的研究方向.     

蒙脱石-聚二甲基硅氧烷复合膜制备及其乙醇/水分离性能

采用CTAB柱撑蒙脱石通过溶液法制备了有机蒙脱石填充聚二甲基硅氧烷（PDMS）膜,研究了填充量等因素对乙醇/水体系渗透汽化分离的影响,通过XRD、SEM等表征手段证明有机蒙脱石与聚合物形成插层型复合物后,膜的机械强度明显改善,膜的分离因子随填充量增加可提高至最大值10。本文从膜的结构及其与组分的相互作用对填充膜中蒙脱石可能存在的渗透通道作用进行了探讨。     

偶联剂对纳米二氧化硅/PDMS复合膜渗透汽化性能影响的研究

用3种硅烷偶联剂3-氨丙基三乙氧基硅烷(AMES)、γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(MEMS)、十六烷基三甲氧基硅烷(HEMS)分别对纳米二氧化硅粒子进行改性,利用制备的改性粒子与PDMS制备了一系列平板复合渗透汽化分离膜,用于乙醇/水溶液分离.实验结果表明:复合膜的渗透汽化性能得到显著的提高.3种改性粒子在提高渗透通量方面:HEMS＞MEMS＞ AMES;在提高分离因子方面,MEMS与AMES对复合膜的影响十分接近,而HEMS远小于前两者.当MEMS改性二氧化硅的质量分数为4％时,在40℃质量分数为10％的乙醇/水溶液中,复合膜的分离因子达到最高值11.17,渗透通量为216.1g/(m2 ·h).     

PTFE-PDMS/PVDF复合膜制备及其渗透汽化性能

制备了以聚偏氟乙烯PVDF超滤膜为底膜的聚四氟乙烯PTFE超细粉体填充聚二甲基硅氧烷PDMS复合膜,并用于氯仿水溶液体系的渗透汽化。采用SEM和接触角分析研究了膜结构及表面性能。研究了PTFE:PDMS质量比、料液流速、料液浓度对渗透汽化性能的影响;采用串联阻力模型分析了渗透汽化氯仿水溶液的传质过程。研究表明,填充PTFE提高了PDMS膜渗透汽化性能;流量大于200 mL min 1时渗透汽化传质阻力主要由膜阻力控制;在流速低于200 mL min 1时,浓差极化产生的氯仿传质边界层阻力最大可达膜阻力的29倍。     

SiO2填充的聚二甲基硅氧烷膜在渗透汽化透醇领域的应用

制备一系列底膜为聚偏氟乙烯(PVDF)、m(SiO_2)∶m(PPMS)比不同的SiO_2/聚二甲基硅氧烷(PDMS)杂化膜。考察了m(SiO_2)∶m(PPMS)比、操作温度等因素对杂化膜透醇性能的影响,并对其微观形貌(SEM)、溶胀性质以及正电子湮没寿命谱(PALS)进行了表征。结果表明,在室温下,以PDMS为主体的m(SiO2)∶m(PPMS)比杂化膜的自由体积孔穴平均半径(0.39nm)介于水、乙醇的分子动力学半径之间,是造成此类膜材料渗透通量普遍偏小的原因。杂化膜的自由体积孔穴数量随着SiO_2填充的增加而下降。     

有机硅烷交联PDMS/陶瓷复合膜的制备及渗透汽化汽油脱硫性能

采用有机硅烷γ-氨丙基三甲氧基硅氧烷（APTMS）,对聚二甲基硅氧烷（PDMS）进行交联改性,以ZrO₂/Al₂O₃陶瓷复合膜为支撑体,制备了一系列有机硅烷交联的PDMS/陶瓷复合膜。通过扫描电镜（SEM）、傅里叶红外光谱（FTIR）、热重分析（TGA）对改性效果和膜结构进行了表征。将所制备的PDMS/陶瓷复合膜应用于渗透汽化脱除模拟汽油中的有机硫化物（噻吩）,考察了交联剂APTMS含量、操作温度、料液含硫量等因素对复合膜渗透汽化脱硫性能的影响。实验结果表明,有机硅烷交联的PDMS膜相比于传统正硅酸乙酯（TEOS）交联的PDMS膜,通量和硫富集因子均有所提高。随着进料温度和原料液中硫含量的升高,膜的渗透通量均增大,而硫富集因子均减小。当APTMS质量分数为15%、进料温度为25℃、噻吩质量浓度为100mg/kg时,渗透通量为0.46 kg/（m²·h）,硫富集因子达到3.5。     

PSF支撑层结构对PDMS复合膜渗透汽化性能的影响

以4种不同结构的聚砜(PSF)作为支撑层,制备PDMS/PSF渗透汽化复合膜,考察其用于乙醇/水体系的分离性能,以研究支撑层结构对渗透汽化复合膜分离性能的影响。采用SEM和EDX分析复合膜表层结构,结果表明,支撑层结构几乎不影响复合膜的选择性,但对膜通量有较大影响,特别是支撑层的表面结构对复合膜性能的影响比断面结构更明显。     

支撑层对硅橡胶复合膜渗透汽化分离性能的影响

引言 为了扩大渗透汽化技术的应用领域,科研工作者需要进一步增强渗透汽化膜的分离性能.从工业化的观点而言,用于实际应用的渗透汽化膜大多是复合膜,它由选择层(或分离层)和支撑层组成.一般认为,选择层决定着复合膜的选择性和通量,支撑层起支撑和机械稳定作用.Nijhuis[1]在从甲苯-水体系中分离甲苯的过程中对均质膜和以聚砜为支撑层的复合膜的分离性能进行了比较;Sturken[2]分别用聚醚酰亚胺和聚偏氟乙烯为支撑层的硅橡胶膜从二氯乙烷-水体系中提取二氯乙烷,他们得到了相同的结论:支撑层的影响可以忽略.然而Scholz[3],Heinzelmann[4],Rautenbach[5],Borges[6],Vankelecom[7],Farooq[8],Lipnizki[9]等均在各自研究中发现,由于基膜和分离层的物理化学性质以及制膜方法等众多因素的存在使得支撑层在一定程度上影响复合膜的分离性能;Feng[10]对均质硅橡胶膜和有微孔支撑层的硅橡胶复合膜的分离性能进行了比较,发现均质硅橡胶膜优先透过异丙醇,而有微孔亲水性支撑层的硅橡胶复合膜则优先透过水,这表明在一定的情况下,支撑层甚至起主导作用并能够决定复合膜的分离性能.因此,通过系统研究以不同多孔材料为支撑层的复合膜对有机物-水溶液的分离性能的影响,能够找到最优的复合膜支撑层,从而能够提高复合膜的分离性能.然而,至今关于支撑层对渗透汽化膜分离性能影响的系统研究仍相当少.     

Influence of binding interface between active and support layers in composite PDMS membranes on permeation performance

Effect of the binding interfaces of composite polydimethylsiloxane (PDMS) membranes on their pervaporation performance was studied. The membranes were made up of PDMS as active skin layer and polysulfone (PSF) or polyamide (PA) as supporting layer. PDMS‐PSF membrane was numbered 1, and PDMS‐PA membrane numbered 2. The pervaporation experiments were carried out by using the composite membranes and dilute ethanol–water mixture. The experimental measurements for the permeation performance under various operating conditions (e.g., feed concentration and temperature) showed that the specific permeation rate of membrane 2 was over membrane 1 by seven times at least. A resistance‐in‐series model was applied to formularize the transport of the permeants. Influence of the binding interfaces between the active skin layer and support layers in these membranes on pervaporation performance was analyzed. The cross section morphology of the membranes and chemical element distribution along membrane thickness were examined by using SEM and EDS. It was found that, although the PDMS intrusion layer into PSF near the interface was only about 2 μm, it gave significant effect on the permeation performance. It implied that the resistance produced by the intrusion layer into PSF was apparently larger than that of PDMS intruding PA and over intrinsic PDMS resistance. These should be probably attributed to structures and formation of the binding interfaces. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2468–2477, 2007     

PDMS/陶瓷复合膜用于正丁醇-水体系的渗透汽化分离

Pervaporation has attracted considerable interest owing to its potential application in recovering biobutanol from biomass acetone-butanol-ethanol (ABE) fermentation broth. In this study, butanol was recovered from its aqueous solution using a polydimethylsiloxane (PDMS)/ceramic composite pervaporation membrane. The effects of operating temperature, feed concentration, feed flow rate and operating time on the membrane pervaporation per-formance were investigated. It was found that with the increase of temperature or butanol concentration in the feed, the total flux through the membrane increased while the separation factor decreased slightly. As the feed flow rate increased, the total flux increased gradually while the separation factor changed little. At 40 C and 1% (by mass) butanol in the feed, the total flux and separation factor of the membrane reached 457.4 g•m2•h1 and 26.1, respec-tively. The membrane with high flux is suitable for recovering butanol from ABE fermentation broth.     

表面偏析法制备用于乙醇渗透蒸发脱水的整体PVA-PES复合膜(英文)

A facile surface segregation method was utilized to fabricate poly(vinyl alcohol)-polyethersulfone (PVA-PES) composite membranes. PVA and PES were first dissolved in dimethyl sulfoxide (DMSO), then casted on a glass plate and immersed in a coagulation bath. During the phase inversion process in coagulation bath, PVA spontaneously segregated to the polymer solution/coagulation bath interface. The enriched PVA on the surface was further crosslinked by glutaraldehyde. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS) confirmed the integral and asymmetric membrane structure with a dense PVA-enriched surface and a porous PES-enriched support, as well as the surface enrichment of PVA. The coverage fraction of the membrane surface by PVA reached up to 86.8% when the PVA content in the membrane recipe was 16.7% (by mass). The water contact angle decreased with the increase of PVA content. The effect of co-agulation bath type on membrane structure was analyzed. The membrane pervaporation performance was evaluated by varying the PVA content, the annealing temperature, feed concentration and operation temperature. The mem-brane exhibited a fairly good ethanol dehydration capacity and long-term operational stability.     

聚二甲基硅氧烷膜中乙醇-水的吸附和渗透蒸发行为

以乙醇/水体系为研究对象,结合F lory-Huggins理论,讨论溶胀过程的热力学行为,用以分析和考察聚二甲基硅氧烷(PDMS)膜在乙醇/水中的溶胀特性及组分间的耦合效应。结果表明,在乙醇质量分数20%—40%,膜的溶胀程度最大。渗透蒸发实验表明,水的渗透速率在乙醇质量分数不大于30%范围内变化很小,而乙醇的渗透速率基本随溶液中乙醇质量分数增加而增大。     

Simultaneously enhancing interfacial adhesion and pervaporation separation performance of PDMS/ceramic composite membrane via a facile substrate surface grafting approach

A facile substrate surface silane-grafting approach was demonstrated to enhance both interfacial adhesion and pervaporation separation performance of PDMS composite membrane. With C₁₆ grafted ceramic substrate, the PDMS/ceramic composite membrane exhibited up to 1.7 times stronger interfacial adhesion force between separation layer and substrate layer, meanwhile 1.5 times larger butanol/water separation factor that is higher than state-of-the-art membranes. This novel approach paves a new avenue to developing composite membranes with high and stable separation performance.     

PDMS涂覆的Al2O3中空纤维膜在ABE/水体系分离中的应用

通过浸渍-提拉的方法制备了PDMS涂覆的Al2O3中空纤维膜,并系统地研究了其用于ABE/水体系的分离过程。首先对制备出的膜进行了形貌表征,SEM电镜照片表明,所用的Al2O3中空纤维支撑体具有非对称结构,海绵孔位于膜壁的中间而指状孔在其两侧。制备出的PDMS涂覆的Al2O3中空纤维复合膜表面致密完好没有缺陷,其厚度小于10μm,说明PDMS层被均匀地涂在支撑体外表面。然后在不同的模拟体系(丙酮-水、丁醇-水、乙醇-水)中,系统地考察了复合膜的性能。实验表明,复合膜具有优异的渗透汽化性能(通量和分离因子)。最后将该复合膜用于ABE-水体系的分离,考察了膜在操作过程中的渗透汽化性能和稳定性,同时将二元体系与四元体系过程对比,讨论渗透汽化对ABE体系的分离作用。