聚二甲基硅氧烷-陶瓷复合膜的正己烷-N2分离性能
调研报告
聚二甲基硅氧烷（PDMS）（二甲基硅油）特性：聚二甲基硅氧烷是二甲基硅氧烷的聚合物，它的体系里没有可以自由移动的电子，离子等带电组分，不能在电场的作用下产生电荷移动的效果，因此它具有良好的绝缘性。
单体：—[—Si(CH3)2—O—]—黏度：5S-230000S安全性：本品无毒无味，对皮肤和粘膜无刺激性，但对眼睛有刺激性。
耐热性.耐寒性、耐水性，表面张力小（液体表面层由于分子引力不均衡而产生的沿表面作用于任一界线上的张力），抗氧化性、对有机物有优先透过性、何为渗透蒸发?1、渗透物从液相主体到膜上游面的对流传质(两股直接接触的流体之间质量传递)-----在膜表面吸附并溶解进入膜中，在膜内浓度差的推动下由膜的上游向下游扩散膜下游面的解吸汽化从膜下游表面向蒸汽相主体扩散。
即液相、膜相、气相。
影响渗透通量的因素：操作温度、料液浓度、流速液膜阻（在总阻力中占50%以上）液相传质系数（随前三种因素的增大而增大）复合膜的制备方法归类：1、将PDMS预聚体溶剂甲苯交联剂甲苯三乙氧基硅烷催化剂二丁基二月桂酸锡按质量比1:0.7：0.04:0.03的比例用电子天平称取并置于洁净干燥的烧杯中，在磁力搅拌器上搅拌10min，使其充分接触，配置成铸膜液。
配置好的铸膜液室温下静置一段时间，除去因搅拌产生的气泡，然后将铸膜液倾倒在水平防治的基板的一端，用刮刀从一端匀速地刮至基板的另一端，一次成膜。
将刮好的膜放入恒温箱中水平放置，在一定温度下静置48h后，将PDMS 膜从基板上剥离，在真空下干燥24h后，裁成特定形状待用。
2、实验中的PS基膜采用相转化法制备，N,N-二甲基乙酰胺为溶剂，乙二醇独甲醚为添加剂，溶液经过搅拌、过滤、静置脱泡后，在玻璃板上用刮刀刮膜，膜水洗后在空气中晾干，备用。
进行交联制备了疏水性更强的渗透汽化膜。
交联剂：乙烯基三乙氧基硅烷（VTES）。
膜的特性：膜表面的水接触角。
将膜样品放在40度真空干燥箱中干燥约24h，室温下在接触角测量仪上测定膜表面的水接触角，调节每次出水量为1uL，每个样品重复测量10次，取平均值。
PDMS固相微萃取膜的研制及对水样中多环芳烃的分析应用
PDMS固相微萃取膜的研制及对水样中多环芳烃的分析应用黄健祥杨运云李攻科*（中山大学化学与化学工程学院广州510275）摘要本文考察了聚二甲基硅氧烷(PDMS)固相微萃取膜的制备条件，采用扫描电镜、热重分析、红外光谱等手段表征膜的性质。
测试证实膜的表面均匀一致，涂层材料热稳定性好、耐溶剂性能好。
采用自制PDMS固相微萃取膜，建立了SPMEM—GC/MS测定水样中PAHs 的分析方法。
方法的线性范围在0.10～1000.00 μg/L之间，检出限在0.02～0.51 μg/L之间，相对标准偏差(RSD)在5.2 %～15.2 %之间，分析实际江水样品，回收率在75.8 %～101.5 %之间，RSD在5.3 %～23.8 %之间。
关键词固相微萃取膜（SPMEM）；多环芳烃（PAHs）1 前言固相微萃取(Solid Phase Microextraction, SPME)[1~7]是二十世纪九十年代初提出并发展起来的快速、灵敏、方便、无溶剂、易于实现自动化并适用于气体、液体和固体样品分析的新颖的样品前处理技术。
但也存在装置价格昂贵，现涂层种类有限，选择性差，对无机离子的萃取分离技术不成熟，对复杂基体样品的萃取选择性和重现性不理想等不足。
固相微萃取膜(Solid-Phase Microextraction Membrane，SPMEM)是将固相微萃取涂层材料均匀的涂布于膜状基材上，将针状的固相微萃取装置发展制作成膜状的固相微萃取膜。
固相微萃取膜继承了固相微萃取的萃取机理，保留了固相微萃取的优点，具有与固相微萃取纤维相似的萃取性能。
固相微萃取膜集提取与浓缩为一体，采用溶剂洗脱的方法解吸，可以通过改变萃取膜的大小和厚度来提高萃取分析的灵敏度，方便地实现与气相色谱、液相色谱以及其它各种分析仪器的联用，是固相微萃取技术发展的一个重要延伸。
多环芳烃（PAHs）是一大类广泛存在于环境中的有机污染物，也是最早被发现和研究的化学致癌物，它们是指两个以上苯环连在一起的化合物，具有相当强的致癌性。
聚二甲基硅氧烷渗透汽化膜的研究进展
聚二甲基硅氧烷渗透汽化膜的研究进展作者：张芯金华峰赵振志来源：《当代化工》2020年第05期摘要：聚二甲基硅氧烷（PDMS）作为一种疏水的橡胶态聚合物材料，可用于渗透汽化技术领域，其对有机物的脱除具有明显的优势，近年来得到了广泛的关注。
介绍了PDMS膜的特点，总结了国内外运用不同材料作为支撑层制备PDMS渗透汽化复合膜的研究进展以及应用情况，指出了PDMS渗透汽化膜存在的问题及其发展方向。
关键词：聚二甲基硅氧烷;渗透汽化;支撑层;复合膜中图分类号：TQ 028.8 文献标识码： A 文章编号： 1671-0460（2020）05-1001-04Abstract： Polydimethylsiloxane （PDMS） is a kind of hydrophobic rubber polymer material which can be used in the field of pervaporation separation. It has obvious advantages for the removal of organic compounds and has received extensive attention in recent years. In this paper， the characteristic of PDMS membrane was introduced， the research progress and application of PDMS composite pervaporation membrane prepared by different materials as support layer were summarized， the existing problems and developing trends in PDMS pervaporation membrane were pointed out.Key words： PDMS; Pervaporation; Support layer; Composite membrane滲透汽化是膜分离技术的新秀，其工作原理为：利用致密高聚物膜作为分离层，在分离液体混合物时，以组分蒸汽压差为推动力，基于不同的组分在聚合物膜中的透过速率、溶解和扩散能力的差异来实现混合物的分离。
有机液优先透过渗透汽化膜
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研究了沸石种类及物化性质对膜渗透性能的影响。其他研究者还对沸石在复合膜中的一些 %A@) 膜， 〔8;， 8!〕 特殊性能进行了研究， 如离子交换性能， 吸附性能， 分子筛效应及憎水 O 亲水性能。陈新等 将合成 发现能进一步改善分离性能， 且分离性能的改善与沸石 的 ):P:M.P:7- $ !沸石进行了酸处理和水热处理， 的填充量及膜的种类有关。 由于接枝共聚主要发生在聚合物的非晶区， 因此会导致聚合物的自由体积减少，使溶 " J ! J " 接枝 剂在膜中的扩散速率下降，而被分离组分的扩散速率由于其与接枝单体的溶度参数相近而得以提 〔8<〕 〔8>〕 高 。邓建平等 用表面光接枝方法， 将具有化学选择性的膜通过化学键连在多孔载体上， 以制备复 〔8H〕 合分离膜。 ’-00-77 等 通过交联在 %A@) 表面接枝憎水性的柔性长链， 降低了水的吸附溶解， 提高了 分离性能。他们还比较了不同功能基团对渗透性能的影响。并发现对 %A@) 膜， 交联度过大将导致渗 透性能下降。 可以调节聚合物的分子结构， 使聚合物的亲水性 O 憎水性适当平衡， 以适应于不 " J ! J 8 共聚和共混 同的欲分离体系。如丙烯酸酯 $ 丙烯酸共聚物和丁苯， 丁腈橡胶。
〔0〕 等温线符合 -&(. / 模型， 呈线性关系， 被描述为自由体积模型 。一般认为， 弹性体中链段的柔性由主 〔1〕 在料液透过的温度下链段 链结构， 侧基和链间的相互作用决定 。玻璃态聚合物的 ! , 通常高于室温，
运动仍然较弱， 因此膜中不存在直接的自由通道， 这时组分的扩散运动成为影响膜分离性能的决定因
渗透汽化膜分离法脱除汽油中有机硫化物的应用
渗透汽化膜分离法在脱除汽油中有机硫化物的应用王雪1013207077 化学工艺13级博渗透汽化技术又称渗透蒸发（Pervaporation，简称PV）技术作为一项新兴膜分离技术，以其高效、经济、安全、清洁等优点，在石油化工、医药、食品、环保等领域广泛应用，成为目前膜分离研究领域的热点之一。
该技术用于液体混合物的分离，其突出的优点是能够以低的能耗实现蒸馏、萃取、吸附等传统方法难于完成的分离任务。
它特别适用于蒸馏法难以分离或不能分离的近沸点、恒沸点混合物及同分异构体的分离；对有机溶剂及混合溶剂中微量水的脱除及废水中少量有机污染物的分离具有明显的技术和经济优势。
一、基本原理渗透汽化是利用膜对液体混合物中各组分的溶解扩散性能的不同，实现组分分离的一种膜过程，见图1（a）。
在渗透汽化过程中，料液侧（膜上游侧）通过加热提高待分离组分的分压，膜下游侧通常与真空泵相连，维持很低的组分分压，在膜两侧组分分压差的推动下，各组分选择性地通过膜表面进行扩散，并在膜下游侧汽化，最后通过冷凝的方式移出1。
有机溶剂脱水渗透汽化分离的原理见图1（b）。
图1（a）Schematic diagram of pervaporation process2图1 （b）有机溶剂脱水渗透汽化分离的原理二、渗透汽化膜1.有机膜渗透汽化的主要作用元件是渗透汽化膜，膜的性能对渗透汽化过程有决定性的影响。
渗透汽化膜按照功能可分为亲水膜、亲有机物膜和有机物分离膜3种。
亲水膜又称为优先透水膜，其活性分离层又含有一定亲水性基团的高分子材料制成，具有一定的亲水性。
目前应用最广泛的亲水性商品膜是GFT膜，其分离层是聚乙烯醇。
在全球商业化的渗透汽化装置中，约90%的GFT膜都是由德国预案GFT公司及其相关单位开发的。
目前已有相关学者开始研究亲水性膜在火箭燃料肼、不对称二甲肼和甲肼脱水过程中的应用3456。
亲有机物膜又称优先透有机物膜，通常由低极性、地比表面积和溶解度参数小的聚合物（如聚乙烯、聚丙烯、有机硅聚合物、含氟聚合物、纤维素衍生物和聚苯醚等材料）制成。
陶瓷中空纤维内表面制备聚二甲基硅氧烷复合膜——从单通道到多通道
ResearchGreen Chemical Engineering—ArticlePolydimethylsiloxane (PDMS)Composite Membrane Fabricated on the Inner Surface of a Ceramic Hollow Fiber:From Single-Channel toMulti-ChannelZiye Dong #,y ,Haipeng Zhu #,Yingting Hang,Gongping Liu ⇑,Wanqin JinState Key Laboratory of Materials-Oriented Chemical Engineering,College of Chemical Engineering,Nanjing Tech University,Nanjing 211816,Chinaa r t i c l e i n f o Article history:Received 4December 2018Revised 1March 2019Accepted 27June 2019Available online 25October 2019Keywords:Ceramic hollow fiber Inner membrane PervaporationPolydimethylsiloxane Butanola b s t r a c tThe fabrication of a separation layer on the inner surface of a hollow fiber (HF)substrate to form an HF composite membrane offers exciting opportunities for industrial applications,although challenges remain.This work reports on the fabrication of a polydimethylsiloxane (PDMS)composite membrane on the inner surface of a single-channel or multi-channel ceramic HF via a proposed coating/cross-flow approach.The nanostructures and transport properties of the PDMS HF composite membranes were optimized by controlling the polymer concentration and coating time.The morphology,surface chemis-try,interfacial adhesion,and separation performance of the membranes were characterized by field-emission scanning electron microscope (FE-SEM),attenuated total reflection Fourier-transform infrared (ATR-FTIR)spectroscopy,the nano-indentation/scratch technique,and pervaporation (PV)recovery of bio-butanol,respectively.The formation mechanism for the deposition of the PDMS layer onto the inner surface of the ceramic HF was studied in detail.The optimized inner surface of the PDMS/ceramic HF composite membranes with a thin and defect-free separation layer exhibited a high flux of ~1800g Ám À2Áh À1and an excellent separation factor of 35–38for 1wt%n -butanol/water mixtures at 60°C.The facile coating/cross-flow methodology proposed here shows great potential for fabricating inner-surface polymer-coated HFs that have broad applications including membranes,adsorbents,composite materials,and more.Ó2020THE AUTHORS.Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company.This is an open access article under the CC BY-NC-ND license(/licenses/by-nc-nd/4.0/).1.IntroductionPervaporation (PV)is considered to be a promising membrane process due to its advantages of high energy efficiency and flexi-ble operation [1].This versatile process can be used in various liquid separations,especially for solvents dehydration,volatile organic compounds (VOCs)recovery,and separation of organic mixtures [2,3].For practical applications,composite membranes consisting of a thin separation layer on top of a porous support have been widely studied.Most of these composite membranesare supported by porous polymeric substrates [4–7].In recent decades,inorganic-supported composite membranes have been of great interest [8]because of the excellent chemical,mechani-cal,and thermal stability of inorganic substrates.Our group has developed a kind of ceramic-supported polymeric membrane for biofuel recovery [9–12],dehydration of solvents [13],desulfuriza-tion of gasoline [14],and reaction-integrated processes [15,16].It has been demonstrated that this type of PV membrane exhibits a good and stable performance due to the confinement effect of the polymer/ceramic interface [17].The rigid ceramic substrate can decrease the configurational space available for the polymer to perform translational motions.Thus,the polymeric layer and the ceramic layer underneath do not swell in a coordinated man-ner,resulting in asymmetric swelling in the polymer/ceramic composite membrane.The reduced swelling of the polymeric layer can improve the membrane separation performance and stability.⇑Corresponding author.E-mail address:gpliu@ (G.Liu).#These authors contributed equally to this work.yCurrent address:Department of Chemical Engineering,Texas Tech University,Lubbock,TX 79409,USA.In addition to improving the membrane material,many recent works have demonstrated that membrane performance can be enhanced by optimizing the membrane configuration.Hollow fibers(HFs),which feature high-packing density,low transport resistance,and a self-supporting structure,have been widely studied for PV and gas separation[18–20].In our previous work, we constructed a high-performance ceramic HF-supported polymer composite membrane by dip-coating a thin and defect-free polymer layer onto the outer surface of a porous ceramic HF [19,21].Meanwhile,by optimizing the cross-sectional configura-tion and packing density,HF modules were designed in order to apply these composite membranes to the PV process[22].Until now,most efforts have focused on the deposition of a polymeric separation layer on the outer(rather than inner)surface of HF sub-strates[20,21,23].In view of industrial applications,HF composite membranes with an inner separation layer are more attractive because the inner separation layer is protected from physical damage during handling operations.Furthermore,the inner-surface technology can be extended to develop a multi-channel composite membrane,which offers great potential for large-scale implementation,since it provides extra packing density andmechanical strength[24].Along with other researchers,our group reported the prepara-tion of porous crystals including zeolite[25]and metal organic frameworks(MOFs)[26,27]on the inner surface of HFs via various crystal growth approaches.However,coating a polymeric layer on the inner surface of a HF is still a great challenge,despite the few attempts that have been reported[28,29].Wang et al.[28] developed a layer-by-layer self-assembly method that requires oppositely charged polymers to prepare polyelectrolyte HF composite membranes.They also reported the creation of an inner-skin HF polydimethylsiloxane(PDMS)/polysulfone membrane via dynamic coating[29].Unfortunately,the prepared PDMS membranes exhibited relatively lowflux and selectivity. The formation of a thin and defect-free layer might be disturbed by the continuousfluid.It is difficult to process a viscous polymer solution in the lumen of an HF using the conventional dip-coating method that is often used for tubes,because theflow of the viscous fluid can be restricted by the limited space of the HF bore.Mean-while,the formation of a uniform and continuous polymer coating with a controlled thickness on the inner surface of an HF would lead to several challenges.It is essential to tune the rheological properties of the polymer solution,the bore-side nanostructures of the HF,and the interfacial characteristics in order to form integrated HF composite membranes.In this article,we propose a coating/cross-flow method to fabricate a polymeric layer on the inner surface of a ceramic HF. Thefirst coating process provides the polymer solution with a sufficient yet stable contact with the HF substrate in order to form a desirable interface and separation layer.The second cross-flow procedure is used to remove the excess coating in order to produce a uniform and thin layer.We demonstrated this methodology by preparing PDMS,the most representative hydrophobic membrane material for PV,on the lumen of a ceramic HF.The membrane morphology and separation performance were optimized by controlling the PDMS concentration and coating time.The methodology for fabricating a PDMS membrane on the inner surface of an HF was then extended from a single-channel HF to a multi-channel HF(Fig.1).The interfacial adhesion between the PDMS layer and the HF substrate was evaluated by the in situ nano-indentation/scratch technique.The separation performance of the as-prepared inner-surface PDMS/ceramic HF composite membranes was evaluated by means of the PV recovery of n-butanol from a water solution.The effects of feed concentration, operating temperature,and long-term operation on the PV performance were systematically investigated.2.Experiments2.1.Membrane preparationPolyvinyl pyrrolidone(PVP),N-methyl-2-pyrrolidone(NMP), polyethersulfone(PESf),and alumina powders(particle size: 300nm,Alfa-Aesar,USA)were mixed with a weight ratio of 2:28:10:60and degassed to form the spinning dope.30:70w/w NMP/water was used as the borefluid.The dope and borefluid were co-extruded using a syringe pump(KD Scientific,USA) through a single-channel spinneret(orifice diameter of1.2mm) into water with an air gap of2cm.The spunfibers were dried at 100°C for12h and sintered at1200°C for12h to form thefinal single-channel ceramic HF substrate.By using a tetra-bore spin-neret with an orifice diameter of4.8mm(the diameter of the four bores is1.2mm each),a multi-channel ceramic HF was prepared by following the same compositions for the dope and borefluid, as well as the same conditions for the spinning,drying,and sinter-ing process.The details of the dope preparation and spinning can be found in previous work[30,31].PDMS(a,x-dihydroxy polydimethylsiloxane,molar mass: 5600gÁmolÀ1,Sigma-Aldrich,USA)polymer was dissolved in n-heptane;the cross-linker tetraethylorthosilicate(TEOS)and the catalyst dibutyltin dilaurate were then added with a weight ratio of100:10:1for the PDMS/TEOS/catalyst.After pre-polymerization for24h,the PDMS solution was coated on the lumen of the verti-cally placed ceramic HF via a coating/cross-flow method with the following two steps:(1)Static coating:The PDMS solution was injected into the bore side of the ceramic HF and kept stable for the required time.(2)Cross-flow:The PDMS solution in the lumen of the HF sub-strate was simply extracted by a syringe.The injection and extrac-tion rate of the PDMS solution was precisely controlled at 60mLÁminÀ1using a syringe pump.For comparison,another two coating methods were carried out:(1)Static coating:The PDMS solution was injected into the bore side of the ceramic HF.After keeping it stable for the required time,the solution was discharged.(2)Cycledflow coating:The PDMS solution was circulated in the bore side of the ceramic HF by a peristaltic pump with aflow rate of60mLÁminÀ1.The coating time was controlled by the cycled flowing time.The PDMS-coated ceramic HFs were dried at25°C for24h,and then heat treated at120°C for12h to obtain the inner-surface PDMS/ceramic HF compositemembranes.Fig.1.A PDMS composite membrane prepared on the inner surface of a multi-channel ceramic HF and its application for biofuel recovery from water.90Z.Dong et al./Engineering6(2020)89–992.2.CharacterizationsAttenuated total reflection Fourier-transform infrared (ATR-FTIR)spectra(AVATAR360,Thermo Nicolet,USA)were recorded from4000to400cmÀ1with32scans and4cmÀ1 resolution for the PDMS densefilm,ceramic HF,or PDMS/ceramic HF composite membrane.Membrane morphology was examined by afield-emission scanning electron microscope(FE-SEM,Hitachi S-4800,Hitachi,Japan).The interfacial adhesion of the composite membrane was measured by the nano-indentation/scratch tech-nique using a NanoTest system(NanoTest TM,Micro Materials,UK), as reported in our recent work[32].2.3.PV measurementThe separation performance of the composite membrane was evaluated by means of PV process[14].The effective length of the PDMS/ceramic HF composite membrane in the module was 5.8cm,with effective membrane areas of1.82and7.28cm2for the single-channel and multi-channel membranes,respectively. The n-butanol/water mixtures were fed into the membrane bore side using a peristaltic pump,while the membrane shell side was vacuumed below450Pa.A water bath was used to maintain a given feed temperature.Permeate vapor was collected by cold traps using liquid nitrogen(N2).The n-butanol concentration was analyzed by a gas chromatograph(GC-2014,Shimadzu,Japan)with a thermal conductivity detector(TCD).The internal standard method using iso-butanol was employed to quantify the n-butanol concentration.The permeate sample was sometimes diluted with water to produce a homogeneous solution for the gas chromatograph injection.PV separation performance is often expressed in terms of totalflux J and separation factor b,calculated as followsJ¼MAÁtð1Þwhere M is the weight of the permeate,A is the effective membrane area,and t is the permeation time interval.b¼Y i =Y jX i=X jð2Þwhere X and Y are the mass fractions of the component i or j in the feed and permeate,respectively.3.Results and discussion3.1.Membrane preparation3.1.1.Ceramic HF substrateThe nanostructures of the HF play a significant role in determining the formation of the polymeric layer of the porous substrate.The ceramic HF substrates used here were fabricated by means of the phase-inversion and sintering method[31,33]. Fig.2(a)shows a digital picture of the prepared porous single-channel ceramic HFs.The average pore size,porosity,and N2 permeance of the ceramic HF substrate were200nm,43.5%, and 4.2Â105molÁmÀ2ÁPaÀ1,respectively.An asymmetricfiber structure was designed for the purpose of inner-surface polymer coating.As shown in Fig.2(b),afinger-like structure was located at the outer side of thefiber wall,while a sponge-like structure was located at the inner side of the wall,whose total thickness was about300l m.Thefinger-like structure,which has a higher porosity and lower transport resistance,acts as an ideal support for the composite structure[19],while the sponge-like structure (Figs.2(c)and(d))provides a relatively dense and smooth inner surface for the coating of the polymer solution and the formation of a thin layer[20].These featured nanostructures of the inner surface are beneficial for controlling the degree of polymer solu-tion penetration and obtaining a thinly coated layer with mini-mum defects.3.1.2.Formation of PDMS layer on the HF inner surfaceAs reported in our previous work[9,13,19,21],polymeric separa-tion layers can be successfully deposited on the outer surface of a tubular or HF substrate via a conventional dip-coating method. However,it is difficult to use the same method to coat an integrated polymeric layer on the inner surface of an HF,presumably due to the low accessibility of the viscous polymer solution to thefiber’s bore side.Kosaraju and Sirkar[34]proposed an interfacial polymeriza-tion method to prepare a thin separation layer on a porous polypropylene substrate for solvent-resistant nanofiltration,in which monomer solutions were alternatively passed through the lumen side.However,that approach was based on two assumptions regarding the coating solution—namely,reactivity and low viscosity, which cannot be found in most polymer-coated PV membranes.In the present work,a coating/cross-flow method is proposed for polymer coating on the inner surface of an HF.Two typical methods(static coating and cycledflow coating)were also studied for comparison.As shown in Fig.3,the cross-linked PDMS solution wasfilled in the bore side of the HF.The polymer solution was adsorbed on the ceramic surface and then penetrated into the pores of the HF substrate to form a transition layer in the interface. After allowing a certain amount of time for static coating,a gentle cross-flow(controlled by a syringe)was introduced to remove the excess polymer solution within thefiber bores.Due to the strong interaction between the polymer chain and the porous ceramic fiber,a uniform and thin PDMS layer was obtained under the sur-facefluidflow(Fig.3(b)).In comparison,in the absence of the cross-flow,the static coating method produced a very thick PDMS layer(>500l m)(Fig.3(a)).The gravity effect of the polymer solu-tion was insufficient to reduce the layer thickness or maintain an even coating.In contrast,in the cycledflow coating method,the polymer layer deposition was inhibited by the continuous surface cross-flow(generally controlled by a peristaltic pump),which led to the separation layer being too thin to prohibit the generation of defects.As displayed in Fig.3(c),almost no PDMS layer was found on the inner surface of the HF coated by a cycledflow of polymer solution.Moreover,bubbles were generated in the polymer solution during the continuousfluidflow,which were prone to result in nonselective voids in the formed polymeric layer.In all,neither the excessively thick(Fig.3(a))nor thin PDMS (Fig.3(c))coated HFs could be expected to exhibit a good separation performance.During the coating/cross-flow approach,the coating process allowed adequate wetting and adsorption of the polymer solution on the ceramic surface.Meanwhile,a favorable polymer–ceramic interfacial layer was formed as the polymer solution penetrated into the ceramic pores[17].Furthermore,the subsequent gentle cross-flow treatment redistributed the surface coating to result in a homogeneous polymeric layer,and controlled the layer within a desired thickness.By combining the two processes,the HF inner-surface coating technique could result in a thin and defect-free polymeric separation layer.A syringe pump can be applied to realize the coating/cross-flow approach for scalable fabrication.The microstructures of the inner surface of the PDMS HF com-posite membrane prepared by the coating/cross-flow method were further investigated by SEM characterization.As shown in Fig.4,a smooth,defect-free PDMS layer was obtained on the inner surface of the single-channel ceramic HF substrate.There was a clear tran-sition layer between the PDMS and the ceramic substrate,formed by the polymer solution penetrating into the porous HF supportingZ.Dong et al./Engineering6(2020)89–9991Fig.2.Morphologies of the single-channel ceramic HF substrate.(a)Digital photo;(b)SEM images of the cross-section;(c)the inner surface;(d)the enlarged inneredge.parison of different methods for preparing an inner-surface PDMS/ceramic HF composite membrane.(a)Static coating method;(b)coating/cross-flow method;(c)cycled flow coating method.Left:preparation schematic;right:cross-section SEM image(s)of HF;insert in part (c):fiber’s inner surface.Preparation conditions for all three methods:PDMS concentration of 10wt%;coating time of 60s.92Z.Dong et al./Engineering 6(2020)89–99layer.This transition layer provided the composite membrane with sufficient interfacial adhesion,resulting in a PDMS layer that tightly covered the inner surface of the ceramic HF with no delamination [35].Using this coating/cross-flow method,we also successfully pre-pared a PDMS separation layer on the inner surface of a multi-channel ceramic HF.As shown in Fig.5,the HF exhibits a regular structure with a uniform distribution of four channels,providing much stronger mechanical strength,which will be discussed later.Each channel had a diameter of ~1mm,and the surface of each was coated with a PDMS separation layer.The enlarged membrane cross-sectional SEM images showed a fiber wall consisting of macro-voids and sponge-like pores,which respectively offered low transport resistance and an even surface for the polymer coat-ing.Like the single-channel HF composite membrane,an inte-grated and uniform PDMS layer was firmly adhered onto the inner surface of the multi-channel HF substrate.In addition to the morphology observation,ATR-FTIR analysis was used to characterize the surface groups of the PDMS dense membrane,ceramic HF substrate,and PDMS/ceramic HF composite membrane.As shown in Fig.6,the peaks that were observed at 1015,1259,and 2963cm À1were attributed to the stretching vibra-tion of Si–O–Si,the bending vibration of Si–CH 3,and the stretching vibration of –CH 3,respectively.These characteristic peaks of the PDMS material [9]further indicated a successful deposition of the PDMS layer onto the inner surface of the ceramic HF.Interfacial adhesion is a key factor in the structural stability of composite membranes during practical separation application.We used a nano-indentation/scratch technique [32,35]to in situ probe the adhesive force of the PDMS layer to the HF substrate;the result is given in Fig.7.According to our previous study [32],the corresponding critical load can be determined by the one-set of failure from the scratch–displacement curve and friction–displacement curve.The adhesion force of the PDMS layeronto the inner surface of the ceramic HF was 32mN,which is as good as that of outer-surface PDMS/ceramic composite membranes (~35mN)[32].3.1.3.Optimization of the preparation conditionsBy further analyzing the preparation process of the inner-surface PDMS HF composite membranes,two critical parameters were found to determine the final membrane structures and sepa-ration performance:①the concentration of PDMS coating solu-tion;and ②the static coating time.The polymer concentration greatly affects the rheological properties of the coating solution and the formation of the separation layer during the solvent evaporation process.In general,a thin polymer layer can be obtained by using a coating solution with a low polymer concentra-tion [29].However,it may be difficult to completely cover a porous substrate using an excessively dilute polymer solution.A coating solution with a low viscosity is prone to penetrating into the sub-strate pores and thus forming defects in the separation layer.There-fore,we studied the effect of PDMS concentration on the separation performance of our membranes.We took the single-channel HF composite membranes as an example.The membrane separation performance was evaluated by the recovery of n -butanol from its aqueous solution via PV,which is an important application for producing bio-butanol from the biomass fermentation process [12].As shown in Fig.8,the total flux of the composite membrane decreased gradually with an increase in PDMS concentration,which can be related to the reverse relationship between the mem-brane thickness and permeation flux.On the other hand,the sepa-ration factor showed a sharp rise (from 26to 40)as the PDMS concentration increased from 5.0wt%to 10.0wt%,and then remained stable for a PDMS concentration greater than 10wt%.This finding suggests that several nonselective defects—caused by excessive pore penetration of the polymer solution—were present in the separation layer prepared with the low PDMSconcentrationFig.4.Typical morphologies of the inner-surface PDMS/single-channel ceramic HF composite membrane.(a)Overall cross-section;(b)cross-section of membrane wall;(c)inner membrane surface;(d)inner membrane edge.Preparation conditions:PDMS concentration of 10wt%;coating time of 60s.Z.Dong et al./Engineering 6(2020)89–9993of 5.0wt%.This membrane had a similar morphology to what is shown in the SEM images in Fig.3(c),in which almost all of the PDMS solution penetrated into the porous substrate.As a result,a continuous separation layer was difficult to achieve.This prob-lem can be avoided as the PDMS concentration reaches 10wt%.The separation factor of 40suggests the formation of a high-quality separation layer on the HF inner surface.It was difficult to enhance this value by further increasing the PDMS concentra-tion,since the separation performance was already approaching the intrinsic selectivity of the PDMS material [36].Thus,in our case,10wt%was regarded as the optimal PDMS concentration to form a thin and defect-free PDMS separation layer on the inner sur-face of the ceramic HF.According to our previous studies [35],the wettability between the substrate surface and the polymer solution influences poly-meric layer formation:First,the solution disperses on the inner surface of the ceramic HF;next,the solution penetrates into the pores of the support;and finally,the polymer layer is deposited onto the surface with the evaporation of the solvent.In general,complete wetting of the polymer solution on the ceramic surface is necessary in order to prepare a PDMS/ceramic composite mem-brane.The wetting process deserves particular attention for the lumen polymeric coating in HFs.Therefore,it was studied by vary-ing the coating time;the effect of coating time on the separation performance is shown in Fig.9.Interestingly,all of the samples prepared with different coating times exhibited a relatively high separation factor (>35).This finding suggests that the HF inner surface can be fully covered by the PDMS immediately (in only 10s,in our case),which may be due to the good wettability of the PDMS/heptane solution on the ceramic surface.It was also found that a composite membrane with a higher separation factor was formed by increasing the coating time,which relates to the degree of penetration of the polymer solution into the HF pores.As demonstrated in our previous work [17],PDMS penetration into the substrate pores can help in the subsequent formation of a top PDMS layer,improving the integrity of the PDMS layer and thus enhancing the membrane selectivity.However,the penetration-induced higher transport resistance would lead to a loss of mem-brane flux.Furthermore,the uniformity of the inner-surface PDMS/ceramic HFs prepared with different PDMS concentrations or dip-coating times was checked by SEM characterization.Under the optimized preparation conditions,the membrane surface was found to be defect-free,and the cross-sectional PDMS layer was uniformly and firmly adhered onto the ceramic HF substrate.These mor-phologies were very similar to the SEM images shown in Fig.4,and are thus not shown here.Overall,the thickness of the inner PDMS coating could be readily controlled by varying eithertheFig.5.Typical morphologies of the inner-surface PDMS/multi-channel ceramic HF composite membrane.(a)Digital photo;(b)SEM images of the overall cross-section;(c,d)the enlarged cross-sections.Preparation conditions:PDMS concentration of 10wt%;coating time of 60s.Fig. 6.ATR-FTIR spectra of (a)the ceramic HF substrate,(b)the inner-surface PDMS/ceramic HF composite membrane,(c)the PDMS dense membrane.94Z.Dong et al./Engineering 6(2020)89–99polymer concentration or the coating time.It should be noted that the transition layer becomes thicker when the polymer solution concentration is decreased and/or the coating time is increased.This results in additional transport resistance in the composite membranes,which would sacrifice the permeate flux,although itmight be helpful for maintaining high selectivity.For a given separation system,it is possible to control the polymer concentra-tion or/and coating time to obtain the desired membrane thickness corresponding to the required flux and selectivity.In addition,we tried different flow rates for extracting the coating solution,and found that an appropriate flow rate (50–70mL Ámin À1in our case)should be used to achieve a sufficient extraction of the coating solution without excessively removing the coated layer.Otherwise,an excessively low or high flow rate would produce a thick or defective membrane layer.This is our preliminary result;more systematic optimization is still underway and will be reported in the future.3.2.Membrane application for bio-butanol recovery3.2.1.Effect of feed concentrationFig.10illustrates the effect of the n -butanol concentration in the feed on the separation performance of the inner-surface PDMS HF composite membrane.A higher feed n -butanol concentration resulted in a much higher total flux while slightly lowering the separation factor.Due to the strong affinity between n -butanol and PDMS,the n -butanol could easy enter the free volumes (cavi-ties)of the PDMS chains,resulting in swelling of the PDMS mem-brane.This phenomenon has been well demonstrated for PDMS-based membranes [37].In this work,it was difficult to measure the degree of swelling of the PDMS layer on the composite mem-branes due to the significant effect of the support layer.Regardless,it is reasonable to speculate that as the n -butanol concentration increases,more n -butanol molecules are adsorbed within the poly-mer chains,increasing the degree of swelling of the PDMS separa-tion layer.Another possible reason for the flux improvement is the improved driving force from the increased feed concentration [38].Consequently,both the n -butanol and the water molecules perme-ated through the membrane more easily,causing the total flux to increase.Furthermore,the molecular kinetic diameter of water (~0.296nm)is smaller than that of n -butanol (~0.505nm),causing water molecules to diffuse more quickly than n -butanol molecules.Thus,a relatively low separation factor was obtained at a high con-centration of n -butanol in the feed.3.2.2.Effect of feed temperatureAs shown in Fig.11,the total flux increased linearly with the increase of feed temperature.The total flux had a three-fold enhancement at 60°C compared with that at 30°C.This may be partially attributed to the larger free volumes of thePDMSFig.7.Nano-indentation results of the inner-surface PDMS/ceramic HF composite membrane.(a)Scratch–displacement curve;(b)scratch load–displacement and friction–displacementcurves.Fig.8.Separation performance of the inner-surface PDMS/single-channel ceramic HF composite membrane for different PDMS concentrations.Preparation condition:coating time of 60s;feed condition:1wt%n -butanol/water at 40°C.Fig.9.Separation performance of the inner-surface PDMS/single-channel ceramic HF composite membrane for different coating times.Preparation condition:PDMS concentration of 10wt%;feed conditions:1wt%n -butanol/water at 40°C.Z.Dong et al./Engineering 6(2020)89–9995。
提高硅橡胶的粘附性制备多层复合膜
Vol40 No6Dec 2020第40卷第6期2020年12月膜科学与技术MEMBRANE SCIENCE AND TECHNOLOGY提高硅橡胶的粘附性制备多层复合膜张旭，孟令鹏，李培$(北京化工大学材料科学与工程学院，北京100029)摘要：以商业化的硅橡胶(PDMS )和添加剂为原料，通过优化添加剂配比，有效地提高了PDMS 层的粘附力，并制备了 Pebax/PDMS/PAN 三层中空纤维复合膜.当PDMS 与添加剂配比为1 : 3、Pebax 涂覆液的质量分数为3%时，复合膜的CO 2通量为115. 6 GPU ,CO 2/N 2选择性为29. 1.证明经过调控的PDMS 层表面更容易粘附连续的无缺陷Pebax 层.关键词：PDMS ； Pebax ；多层复合膜；CO 2分离中图分类号：TQ31文献标志码：A文章编号：10078924(2020)06003707doi ： 10. 16159/j. cnki. issnl0078924. 2020. 06. 006膜技术是一种节能高效的分离技术，在21世纪得到了飞速发展•中空纤维气体分离膜具有能耗低、 比表面积大、环境友好、容易安装等优点,在石油、冶金、机械、航天、食品保鲜等领域有着极其广阔的应用前景1,如从空气中提纯N 2、从烟道气中捕集CO 」3'、从天然气中分离CO 」4—5'等•已经报道的膜材料很多,但得到商业化应用的不超过10种6•其原因之一是新材料价格昂贵，难于工业推广•而将新材料涂覆在多孔支撑层上形成 复合膜，可以极大地节省材料用量，提高其工业应用 的可行性.但在复合膜的制备过程中，界面相容性差、分层、表面缺陷等问题造成其气体分离性能下降 严重&7'.自Henis 等囚发明了用硅橡胶修复聚合物膜表 面缺陷的方法后，气体分离膜第一次实现了工业化 应用•硅橡胶拥有很低的表面能，很容易覆盖其他材料的表面，但是其他材料很难涂覆到硅橡胶表 面•为了制备多层复合膜，研究者往往通过对硅橡 胶表面改性，以提高其表面能和粘附力.然而改性方法通常比较复杂,很难得到商业化推广•本课题的研究目的是利用商业化材料提高硅橡胶的粘附 性,制备气体分离多层复合膜.以德国瓦克公司的Dehesive ® 944硅橡胶为基材，CRA 为添加剂.通过向Dehesive ® 944中添加CRA 以提高硅橡胶的粘 附性能•为了评价粘附效果，通过拉伸方法测量改性硅橡胶对3M 胶条的粘附力•随后，制备了聚丙 烯猜(PAN )中空纤维支撑层，在中空纤维外表面依次涂覆了硅橡胶层和高气体选择性的Peb-axl657层：9—10'.研究了涂层的配方、涂覆液浓度和涂覆液溶剂对中空纤维复合膜皮层粘附效果和气 体分离性能的影响.1实验部分1.1材料PAN (相对分子质量150 000), BASF ；聚二甲基硅氧烷(PDMS, Dehesive ®944乙烯基PDMS,黏度20 000 mPa • s )、添加剂CRA (主要成分为含氢硅油，黏度500 mPa • s ),德国瓦克(Wacker )公司；Pebaxl657,法国阿科玛公司；正己烷、N -甲基毗 咯烷酮(NMP )、二甘醇(DG )、甲醇(MeOH )、乙醇收稿日期：2020-06-25；修改稿收到日期：2020-07-18基金项目：国家自然科学基金(51773011)第一作者简介：张旭(1995-),男，山东荷泽人，硕士，主要从事气体分离膜的研究，E-mail ： zxl8765039316@163. com.$ 通讯作者，E-mail : lipei@mail. buct. edu. cn引用本文：张 旭,孟令鹏，李 培•提高硅橡胶的粘附性制备多层复合膜膜科学与技术,020,0(6):37 — 43.Citation ： ZhangX ， MengLP ， LiP'Fabricationofmulti-layercompositemembranesbyincreasingtheadhesiveforceofthePDMSgu t erlayer &J ''MembraneScienceandTechnology (Chinese #，2020，40(6#：37—43'・38・膜科学与技术第40卷（EtOH ）,河北化工试剂厂；CO2、N2、O2 （纯度>99.99%）,北京城 公司.1.2 PAN 中空纤维膜的制备1. 2. 1中空纤维纺丝pan 中 维采用 化法制备&1'.将 PAN 在 100 L中12 h ,用分子NMP•然后将PAN/DG/NMP 按照20/5/75的质量膜液，静置脱<=«芯液|o.4| 0.6 |o.4)mm(b)料液凝固浴收丝池=IF喷丝头N2_M 吨1芯液占铸膜液图1中空纤维纺丝装置(a)及纺丝头结构(b)The hollow fiber spinning equipment (a) and the structure of spinneret (b)Fig.11. 2. 2中空纤维的后处理方法将中 维膜放入到自来水中浸泡3 d,每12 h水1次.目的是除去中 维中残留的和非•中维湿膜交换法•首先，将其入甲醇中 ，每30 min醇1次，重复5次;然后用正己烷 4次;最后在 中 .1.3致密平板膜的制备PDMS/CRA 共混膜通过浇铸法制备.将Dehe-sive ®944（30%甲苯溶液）、CRA 、交联剂和催化剂混合均匀后注入聚乙烯培养皿中• 挥发后"室置2d,形成交联膜，厚度为（0.1 + 0.05） mm.致密膜的 和表1所示.为了制备Pebax膜,首先将Pebax 颗粒 在乙醇/水（体积比85/15）的混合中.将Pebax 入聚乙烯培养皿,将培养皿在真中放置18〜24 h 得到厚度为（0. 1 士005） mm 的 膜'表1 PDMS/CRA 平板膜的配比Table1 CompositionsofPDMS /CRAdenseflatmembranes膜PDMS 质量分数/%CRA 质量分数/%M11000M25050M3333667M42575•中空纤维纺丝过程 1所示•选用内外径尺寸为0. 6 mm/1. 4 mm 的中空纤维纺丝头，铸膜液在0. 6 MPa 的压力下由料液泵注入喷丝头料液通道"另一 塞泵注入 的 •芯液和 中分别以3和4 mL/min 的流速同时 ，经过3 cm隙后进入到28 L 的水中固化成中 维" 自由落体（3 m/min ）的方式收集.1.4中空纤维复合膜的制备141 PAN 中维膜 的 备从PAN 中 维膜丝中 取10〜15 cm的膜丝，放入不 中•顶端用和环氧，在另一端（膜）使用化环氧，得到中维 试组器.1. 4 2涂覆液的制备将Dehesive ® 944和不同比例的CRA 溶解在正己烷中，整 含量 在质量分数3%.将Pebax于乙醇/水（85/15）混合 中，得到不同质量度的Pebax 水溶液.将滤后置于 中低温（2 °C ）保存.143 复合膜的 备中 维复合膜的制备流程 2所示•将单膜 于涂覆液中 5 s 后,室 置48h 得到PDMS/PAN 双层复合膜.PDMS/PAN 复合膜在涂覆Pebax 后，" 12 h,得到Pebax/PDMS /PAN 层复合膜'1.5表征1.5 1水接试将PDMS/CRA 致密平板膜裁剪成1 cm 2的正 方形，由3M 双面 定在玻璃板上.将样 在水接 量仪上（R - 82b ，浙江华科数字技术公司）•样品取5处不同位置测量水接触角，取平均值.第6期张旭等：提高硅橡胶的粘附性制备多层复合膜・39・图2复合膜的浸涂过程示意图Fig.2Schematic diagram of dip coating式中：P为气体的渗透系数，Barrer[1Barrer_ 1.5.2表面粘附力测试如图3所示，将致密平板膜裁剪成小样条，样条7.5X10—14cm'(STP)・cm/(cm2*s・Pa)'V为两面由双面胶粘贴在两块横截面长1.0cm、宽低压室的容积"mh A为测试时聚合物膜的有效面0.15cm的玻璃条上用DMA仪器(Q800,TAinstrument)的将薄膜和胶条分开量，用以表征薄膜的表面粘•图3DMA测试薄膜粘附性能的样条Fig3Sampleforadhesiontesting1.5.3SEM表征中空纤维复合膜的多层结构由SEM(S-4700,Hiachi)观察..滑的断面结构，取2〜3mm长的中维在液氮中淬断，样品表面喷金后试'1.5.4气体传质性能测试(1)膜的质性能分离层的传质性能用膜通过恒体积变压法测量&2'将样品封装在膜室中"莫的有效直径为0.5cm.膜上方的法兰腔室及管路空间、储属于高压室"膜的上；膜下方的多孔板、属于低压室，称为膜的匚空间,其体积•测试前需要将装置内各处态,然后向膜的上内通入0.2〜0.3MPa的测试・•膜进入下游空间，下游的表会记内的时间的变化情况•纯气体渗透系数通过式(1)计算.273X1010 P_760VlAJ'~7~7'p2(1#X积"m2；J试温度，K；l为膜的厚度"m；p2试时高压室内的，即上？力，kPad D i/d/为低压室内时化稳定时的化"kPa/s'(2)中维复合膜的性能试将度10〜15cm的中维备器，用图4中装置测试N2、02和C02在膜中的传质'在试程中"膜的膜03MPa"渗透J)式(2)'J_Q/(A・(2)式中：J为气体的渗透速率,GPU&GPU_7.5X10—10cm3(STP)/(cm2・s・Pa)'Q为气体通量"cm3/s；A是膜面积,cm2；"D为中维膜两侧的"Pa'理想气体的选择性a由式(3)计算."a/b_J a/J b(3)2结果与讨论2.1PDMS、Pebax和PDMS/CRA共混膜的气体渗透性能本研究使用硅橡胶(PDMS或PDMS/CRA)和Pebax中维复合膜的分离层'复合膜的性和分离层的内在性.分离层的分离性能量膜，如表2所示•(Ml〜M3)的渗透性能接近"寸3的渗透性和性的区别在10%以内.说明PDMS/CRA共混膜中CRA的含量对质性能影响・Pebax的C02/N2选择性是的3倍"旦C02渗透性降低了24倍.渗透性降低、选择性升高符合分离膜的trade-off规律.此外"Pebax和的分离性能与文献报道的数据类似713，证明测量结果是的.・40・膜科学与技术第40卷图4中空纤维膜气体渗透性能测量系统Fig.4A schematic diagram of hollow fiber gas permeation testing system表2PDMS.Pebax和PDMS/CRA共混膜的气体渗透性能Table2Gas permeation properties of PDMS,Pebax and PDMS/CRA flat membranes 膜丿N2/Barer丿o2/Barrer!co2/Barer o2/n2CO2/N2 M1464.4士201157.6士806177.7士200 2.413.3 M2612.2士251247.3士1006231.0士230 2.210.2 M3602.6士301238.3士905959.6士300 2.19.9 M4639.2士401597.3士1506353.5士400 2.59.9 Pebax7.3士0.332.0士2.0255.8士5.0 4.234.42.2CRA对硅橡胶亲水性的影响聚合物的高表面能有利于提高界面粘附性，而水接数据可以用于判断的表面能大小•如5所示，纯膜的水接触角为126。
吸附剂填充PDMS复合膜的渗透汽化透醇性能
126一、介绍渗透汽化是利用混合物中各组分通过膜时溶解与扩散速率的不同来实现选择性分离的新型膜分离技术。
将其与生物反应器结合对于实现连续发酵具有重大的意义，其不仅对于微生物没有任何不利影响，而且具有能耗低、收益高、绿色无污染等优点。
通常来说，采取抽真空手段，可使液体混合物部分汽化并通过膜的运输，到达下游侧。
然后当温度降低时，蒸气在收集器中冷凝液化。
膜材料的选择是渗透汽化过程的关键。
按膜材料本身性质不同，可分为高分子膜、无机膜和有机/无机复合膜。
其中，有机高分子优先透醇膜材料种类多、韧性好，但在高温高压下及有机溶剂中稳定性较差。
而疏水无机膜具有耐高温、耐腐蚀、易清洗和消毒、使用寿命长等优点，但其高昂的价格及易碎的性质限制了其应用。
为了克服以上二者的缺点，集合二者的优点，研究工作者更青睐于由无机填充剂和聚合物组成的杂化膜。
对于杂化膜的聚合物活性层，PDMS（聚二甲基硅氧烷），俗称“硅橡胶”，具有良好的热稳定性、耐溶剂性和化学稳定性，被认为是该领域最有前途的膜材料之一。
二、无机填充剂目前，常用的无机填充剂有活性炭、炭黑、沸石分子筛、碳分子筛、气相二氧化硅和氧化镁等。
其中，沸石是被研究最多的，它表现出优异的分离性能。
沸石是一种疏水的铝硅酸盐结晶，孔径大小均匀，通常在0.3-1.0nm。
对于较小的孔径，分子根据固有性质如分子大小和吸附强度以不同的速率通过这些孔进行吸附和扩散。
此外，随铝含量的降低，沸石由亲水变为疏水。
由于沸石表面积大（高达1000m2/g）、孔体积大且孔径分布均匀，沸石已被广泛应用于化学和物理研究中，如择形催化和吸附剂。
近年来，为了提高膜的渗透汽化性能，将多晶沸石混入硅橡胶内，制备出了MMMs。
Te Hennepe等在1987年最先报道了沸石填充膜在乙醇分离方面的研究，文章中结果表明当硅沸石质量含量从0增加到70%的时候，乙醇的渗透选择性能显著提高，分离因子从7上升至40，通量从0.02L·m2h1提高到0.045L·m2h1，这意味着乙醇分子较易通过硅沸石。
Cu3BTC2对聚二甲基硅氧烷聚醚酰亚胺复合膜气体分离的改性的研究（可编辑..
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聚二甲基硅氧烷基板
聚二甲基硅氧烷基板全文共四篇示例，供读者参考第一篇示例：聚二甲基硅氧烷基板是一种广泛用于微电子器件制造的基板材料，也被称为PDMS基板。
它具有优异的机械性能、化学稳定性和光学透明性，被广泛应用于生物医学、研究和微加工领域。
本文将介绍聚二甲基硅氧烷基板的特性、制备方法以及应用领域等方面。
一、聚二甲基硅氧烷基板的特性1. 优异的机械性能：聚二甲基硅氧烷基板具有良好的柔性和拉伸性，可以经受多次弯曲而不破裂，适用于柔性电子器件的制备。
2. 化学稳定性：聚二甲基硅氧烷基板具有出色的抗化学腐蚀性能，可以在各种恶劣环境下稳定工作，适用于生物医学器件的制备。
3. 光学透明性：聚二甲基硅氧烷基板透明度高，适用于光学器件的制备，可以作为透明基板来支撑各种材料的薄膜。
4. 表面光滑性：聚二甲基硅氧烷基板表面光滑，有利于薄膜的均匀沉积，使得器件性能更加稳定。
1. 溶液浇铸法：将聚二甲基硅氧烷溶液倒入模具中，放置一段时间后固化成基板形态。
3. 激光切割法：利用激光技术对聚二甲基硅氧烷基板进行切割加工，制备出所需尺寸的基板。
1. 生物医学领域：聚二甲基硅氧烷基板在生物医学传感器、生物芯片等领域被广泛应用，具有良好的生物兼容性和化学稳定性。
4. 柔性电子领域：聚二甲基硅氧烷基板的柔性和拉伸性使其适合制备柔性电子器件，如可穿戴设备、柔性显示屏等。
第二篇示例：聚二甲基硅氧烷基板的优势在于其化学性质稳定，对细胞无毒、无害，能够提供一个优良的生长环境。
聚二甲基硅氧烷基板的表面性质可通过改变制备条件来调控，例如通过调整制备材料的比例、加入表面活性剂或填料等方法，可以改变基板的表面疏水性、亲水性、粗糙度等特性，从而可以实现对细胞黏附、增殖、形态的调控。
在细胞培养方面，聚二甲基硅氧烷基板具有优异的生物相容性，不会对生长在其表面的细胞产生毒性反应。
细胞可以在其表面黏附、增殖，并保持其正常形态和功能。
聚二甲基硅氧烷基板具有较好的柔韧性和可塑性，可以根据实验需要制备成不同形状和尺寸的基板，适应各种实验条件和设备要求。
聚二甲基硅氧烷的作用
聚二甲基硅氧烷的作用聚二甲基硅氧烷的风险级别是2级（1级最安全）。
英文名：Polydimethylsiloxane它又叫硅灵，二甲基硅油成分的主要风险是：硅油。
在产品中主要是起到成膜剂,柔润剂,表面活性剂等目的。
在化妆品和日化产品中的功效主要是肌肤调理。
聚二甲基硅氧烷又称为二甲基硅油，是一种液体混合物，由一系列以三甲基硅氧烷为末端的，含不同单位个数的二甲基硅氧烷单元的聚合物组成，属于有机硅聚合物(这类聚合物常被称为硅酮），是最常用的硅基有机化合物。
聚二甲基硅氧烷，(Polydimethylsiloxane)，是一种疏水类的有机硅物料。
在化妆品中聚二甲基硅氧烷除直接使用外，为了使甲基硅油分散好，便于浸渍，喷涂，提高效率。
也可配成溶液型，脂类，乳液型三种类型使用。
其与衍生物都是化妆品的优质原料，具有良好的护肤功能，属于化妆品原料中的合成油脂。
本品无毒，对皮肤和粘膜无刺激性，但对眼睛有刺激性，一般公认是安全的。
聚硅氧烷又称硅油或硅酮, 它与其衍生物是化妆品的一种优质的原料，具有生理惰性和良好的化学稳定性，无臭、无毒，对皮肤无刺激性，有良好的护肤功能。
具有润滑性能，抗紫外线辐射作用，透气性好，对香精香料有缓释放作用，抗静电好，具有明显的防尘功能；稳定性高，不影响与其它成分匹配。
常用的有聚二甲基硅氧烷、聚甲基苯基硅氧烷、环状聚硅氧烷等。
聚二甲基硅氧烷由于具有较好的柔软性，在化妆品中常取代传统的油性原料，如石蜡、凡士林等来制造化妆品，如膏霜类、乳液、唇膏、眼影膏、睫毛膏、香波等。
聚硅氧烷是这类物质的总称，也称为硅酮或硅油，都是这一类的物质。
在化妆品中，具有润滑性能、抗紫外线的作用，透气性好，具有明显的防尘功能，在化妆品中也用来取代传统的油脂原料，这是根据聚二甲基硅氧烷具有较好柔软性的特性，护肤品中通常都会用于保湿性制品中，一些高档护肤品也都会加以应用。
聚甲基苯基硅氧烷为无色或浅黄色透明液体，对皮肤渗透性好，用后肤感良好，可增加皮肤的柔软性，加深头发的颜色，保持自然光泽，常用在高级护肤制品以及美容化妆品中。
聚硅氧烷聚二甲基硅氧烷
聚硅氧烷相关资讯聚二甲基硅氧烷Dimeth ylsil icone fluid[63148-62-9] 二甲基硅油,分子主链由硅氧原子组成,与硅相连的侧基为甲基,无色透明,无毒无嗅的油状物。
具有优异的电绝缘性能和耐热性,闪点高,凝固点低,可在-50～200℃温度范围内长期使用。
黏温系数小,压缩率大,表面张力小,憎水防潮性好,比热容和导热系数小。
实际上不溶于水。
聚二甲基硅氧烷聚二甲基硅氧烷- 用途1、电器电子工业：电子插接件等。
2、纤维、皮革：憎水剂、柔软剂、手感改进剂、染色工业的消泡剂、缝制线的润滑。
3、医药、食品：酿造、发酵时间的消泡。
4、橡胶、塑胶、胶模、抛光。
5、化妆品添加剂、憎水、耐候性涂料。
--------------------------------------------------聚二甲基硅氧烷微流控芯片的紫外光照射表面处理研究孟斐陈恒武方群朱海霖方肇伦作者单位：浙江大学化学系,微分析系统研究所,杭州,310028高等学校化学学报=========================================================================== ==========聚硅氧烷聚硅氧烷结构式聚有机硅氧烷（简称聚硅氧烷），是一类以重复的Si-O键为主链，硅原子上直接连接有机基团的聚合物，其通式为，其中，R代表有机基团，如甲基，苯基等；n为硅原子上连接的有机基团数目（1~3之间）；m为聚合度（m不小于2）。
其商品化的产品包括：硅油、有机硅环体、硅橡胶、硅树脂等。
隔热效果很好，在航空领域中有很重要的地位。
聚硅氧烷在历史上曾被称为“硅酮”（Silico ne），目前硅酮也会出现在某些场合，如商品目录中。
在中国，习惯将硅烷单体和聚硅氧烷统称为有机硅化合物，并称聚硅氧烷液体为硅油，聚硅氧烷橡胶为硅橡胶，聚硅氧烷树脂为硅树脂。
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第４１卷第５期２０１９年９月南㊀京㊀工㊀业㊀大㊀学㊀学㊀报㊀（自然科学版）ＪＯＵＲＮＡＬＯＦＮＡＮＪＩＮＧＴＥＣＨＵＮＩＶＥＲＳＩＴＹ（ＮａｔｕｒａｌＳｃｉｅｎｃｅＥｄｉｔｉｏｎ）Ｖｏｌ．４１Ｎｏ．５Ｓｅｐ．２０１９ｄｏｉ：１０．３９６９／ｊ．ｉｓｓｎ．１６７１－７６２７．２０１９．０５．０１７聚二甲基硅氧烷陶瓷复合膜的正己烷Ｎ２分离性能宗传欣，杨小泉，周浩力，金万勤（南京工业大学化工学院材料化学工程国家重点实验室，江苏南京２１１８００）收稿日期：２０１９－０７－０７基金项目：国家重点研发计划（２０１７ＹＦＣ０２１０９０１）；江苏省 六大人才 高峰项目（ＪＮＨＢ－０４１）；江苏高校 青蓝工程 ；材料化学工程国家重点实验室自主课题（ＺＫ２０１７１５）作者简介：宗传欣（１９９４ ），男，Ｅ⁃ｍａｉｌ：ｚｏｎｇｃｘ１９９４＠ｎｊｔｅｃｈ．ｅｄｕ．ｃｎ；周浩力（联系人），副教授，ｚｈｏｕｈｌ＠ｎｊｔｅｃｈ．ｅｄｕ．ｃｎ；金万勤（联系人），教授，Ｅ⁃ｍａｉｌ：ｗｑｊｉｎ＠ｎｊｔｅｃｈ．ｅｄｕ．ｃｎ．引用本文：宗传欣，杨小泉，周浩力，等．聚二甲基硅氧烷陶瓷复合膜的正己烷Ｎ２分离性能［Ｊ］．南京工业大学学报（自然科学版），２０１９，４１（５）：６４９－６５５．摘㊀要：挥发性有机物（ＶＯＣｓ）是大气污染物之一，其排放不仅造成资源浪费，还危害环境与人体健康，如何有效回收处理ＶＯＣｓ是当下亟需妥善解决的问题㊂本文采用膜分离技术，考察聚二甲基硅氧烷（ＰＤＭＳ）陶瓷复合膜在不同温度㊁不同浓度㊁不同进料流量㊁不同渗透侧压力的条件下对典型医药行业ＶＯＣｓ废气（正己烷Ｎ２体系）的分离效果㊂结果表明：ＰＤＭＳ陶瓷复合膜可有效分离回收摩尔分数为３％正己烷Ｎ２体系，在进料流速为１ ２ｍ３／ｈ㊁进料温度为３０ħ㊁真空度为２ ５ｋＰａ时，正己烷通量约为１２ｍｏｌ／（ｈ㊃ｍ２），Ｎ２通量约为２６ ５ｍｏｌ／（ｈ㊃ｍ２），选择性约为１７㊂实验进一步研究了复合膜在６５ｄ使用周期内的分离稳定性，结果显示复合膜在正己烷Ｎ２体系中，通量和选择性没有较大的波动，分离性能稳定，说明ＰＤＭＳ陶瓷复合膜在ＶＯＣｓ回收利用方面具有较好的工业前景㊂关键词：挥发性有机物；ＰＤＭＳ陶瓷复合膜；正己烷中图分类号：ＴＱ０２８．８㊀㊀㊀㊀㊀㊀文章编号：１６７１－７６２７（２０１９）０５－０６４９－０７Ｓｅｐａｒａｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｏｆｎ⁃ｈｅｘａｎｅ⁃Ｎ２ｂｙＰＤＭＳ⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅＺＯＮＧＣｈｕａｎｘｉｎ，ＹＡＮＧＸｉａｏｑｕａｎ，ＺＨＯＵＨａｏｌｉ，ＪＩＮＷａｎｑｉｎ（ＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＭａｔｅｒｉａｌｓ⁃ＯｒｉｅｎｔｅｄＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＣｏｌｌｅｇｅｏｆＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＮａｎｊｉｎｇＴｅｃｈＵｎｉｖｅｒｓｉｔｙ，Ｎａｎｊｉｎｇ２１１８００，Ｃｈｉｎａ）Ａｂｓｔｒａｃｔ：Ｖｏｌａｔｉｌｅｏｒｇａｎｉｃｃｏｍｐｏｕｎｄｓ（ＶＯＣｓ）ａｒｅｏｎｅｏｆｔｈｅａｔｍｏｓｐｈｅｒｉｃｐｏｌｌｕｔａｎｔｓ．ＴｈｅｅｍｉｓｓｉｏｎｓｏｆＶＯＣｓｎｏｔｏｎｌｙｌｅａｄｔｏｔｈｅｗａｓｔｅｏｆｒｅｓｏｕｒｃｅｓ，ｂｕｔａｌｓｏｅｎｄａｎｇｅｒｔｈｅｅｎｖｉｒｏｎｍｅｎｔａｎｄｈｕｍａｎｈｅａｌｔｈ．Ｐｏｌｙｄｉｍｅｔｈｙｌｓｉｌｏｘａｎｅ（ＰＤＭＳ）⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｗａｓｓｅｌｅｃｔｅｄｆｏｒｔｈｅｓｅｐａｒａｔｉｏｎｏｆｔｈｅｔｙｐｉｃａｌＶＯＣｓ（ｎ⁃ｈｅｘａｎｅ⁃Ｎ２）ｉｎｐｈａｒｍａｃｅｕｔｉｃａｌｉｎｄｕｓｔｒｙ．Ｔｈｅｅｆｆｅｃｔｓｏｆｏｐｅｒａｔｉｏｎｃｏｎｄｉｔｉｏｎｓｏｎｍｅｍｂｒａｎｅｐｅｒｆｏｒｍａｎｃｅｗｅｒｅｉｎｖｅｓｔｉｇａｔｅｄａｔｄｉｆｆｅｒｅｎｔｆｅｅｄｃｏｎｃｅｎｔｒａｔｉｏｎｓ，ｔｅｍｐｅｒａｔｕｒｅｓ，ｆｅｅｄｖｏｌｕｍｅｓａｎｄｐｅｒｍｅａｔｅｓｉｄｅｐｒｅｓｓｕｒｅｓ．ＲｅｓｕｌｔｓｓｈｏｗｅｄｔｈａｔＰＤＭＳ⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｃｏｕｌｄｅｆｆｅｃｔｉｖｅｌｙｓｅｐａｒａｔｅ３％ｎ⁃ｈｅｘａｎｅ⁃Ｎ２．Ｗｈｅｎｔｈｅｆｅｅｄｖｏｌｕｍｅｗａｓ１ ２ｍ３／ｈ，ｔｈｅｐｅｒｍｅａｔｅｓｉｄｅｐｒｅｓｓｕｒｅｗａｓ２ ５ｋＰａ，ｈｅｘａｎｅｆｌｕｘｗａｓａｂｏｕｔ１２ｍｏｌ／（ｈ㊃ｍ２）ａｎｄＮ２ｆｌｕｘｗａｓａｂｏｕｔ２６ ５ｍｏｌ／（ｈ㊃ｍ２）ａｔ３０ħｃｏｕｌｄｂｅｏｂｔａｉｎｅｄｗｉｔｈｔｈｅｓｅｌｅｃｔｉｖｉｔｙｗａｓａｂｏｕｔ１７．Ｔｈｅｆｕｒｔｈｅｒｓｔｕｄｙｏｆｔｈｅｍｅｍｂｒａｎｅｓｔａｂｉｌｉｔｙｆｏｒ６５ｄｐｒｏｖｅｄｔｈａｔｔｈｅｓｅｐａｒａｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｏｆｔｈｅｍｅｍｂｒａｎｅｗａｓｓｔａｂｌｅｄｕｒｉｎｇｔｈｅｉｎｖｅｓｔｉｇａｔｅｄｔｉｍｅｒａｎｇｅ，ｗｈｉｃｈｉｎｄｉｃａｔｅｄｔｈａｔＰＤＭＳ⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｈａｄｐｏｔｅｎｔｉａｌｓｆｏｒｔｈｅｒｅｃｏｖｅｒｙｏｆＶＯＣｓ．Ｋｅｙｗｏｒｄｓ：ＶＯＣｓ；ＰＤＭＳ⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅ；ｎ⁃ｈｅｘａｎｅ㊀㊀挥发性有机物（ＶＯＣｓ）作为大气污染物的一种，其排放不仅造成资源浪费和经济损失，还会形成ＰＭ２ ５和臭氧，危害人体健康［１］㊂因此，国家已制定了多条法律㊁法规来限制ＶＯＣｓ排放㊂为应对严格的排放标准，研究者已开发了多种技术来实现ＶＯＣｓ减排目标［２］㊂膜分离技术作为末端治理技术的一种，由于具有能耗低㊁安全㊁无需后处理和可集成性强等优点，被认为是最具发展前景的ＶＯＣｓ处理技术之一［３］㊂在膜分离过程中，膜性能的高低影响着膜法ＶＯＣｓ处理的工业化应用成本㊂为此，一部分研究者通过膜材料的优化设计或改性来实现膜分离性能的提升［４］㊂但这一过程开发周期长，对于日益严重的大气污染现状，这一过程实现工业化还需较长的时间［５］㊂另一部分研究者发现，膜分离性能除了受到膜材料性能的影响外，操作条件也是一个重要的影响因素㊂选择不当会极大地影响膜本征分离性能的展现［６］㊂因此，通过对现有的可以商业化生产的膜进行操作条件优化，有助于提升膜分离性能㊂但目前详细研究操作条件对膜分离性能的影响规律的报道还较少㊂为此，笔者以实验室制备的聚二甲基硅氧烷（ＰＤＭＳ）陶瓷复合膜为研究对象，以医药行业典型废气正己烷Ｎ２为代表性分离体系［７］，通过考察不同操作条件，如温度㊁浓度㊁流速㊁真空度等对膜分离性能的影响，研究其变化规律并解释内在机制；同时考察ＰＤＭＳ陶瓷复合膜正己烷Ｎ２分离性能的长期稳定性，以期为膜法工业化应用提供重要的理论指导㊂１㊀实验１．１㊀材料及仪器ＰＤＭＳ陶瓷复合膜，自制［８⁃９］；正庚烷㊁正丙醇，中国医药集团上海化学试剂公司；去离子水，自制；陶瓷支撑体，南京九思高科技有限公司㊂气相色谱仪（ＧＣ，ＧＣ２０１４型，日本Ｓｈｉｍａｄｚｕ公司）；扫描电子显微镜（ＳＥＭ，Ｓ４８００型，日本Ｈｉｔａｃｈｉ公司）；中试实验装置，自制㊂１．２㊀复合膜的表征及其性能测试１．２．１㊀ＳＥＭ表征复合膜表面和断面通过液氮清洗后，在表面均匀喷涂一层导电的金颗粒㊂通过扫描电子显微镜在工作电压５ｋＶ㊁工作电流１０μＡ条件下得到膜表面和断面的微观形貌以及分离层厚度㊂１．２．２㊀膜分离实验膜法正己烷Ｎ２分离装置示意图如图１所示㊂采用质量流量计控制Ｎ２流速，一路气提气进入正己烷料液罐，通过鼓泡的方式带出正己烷蒸气并与另一路稀释气混合；两路气体以特定的比例混合，配成特定浓度的原料气进入膜组件内进行分离㊂ＰＤＭＳ陶瓷复合膜长度为８０ｃｍ，外径为１２ｍｍ，内径为８ｍｍ，膜管环隙直径为１６ｍｍ，６根膜管串联使用，有效膜面积为０ １８ｍ２，膜下游侧通过抽真空的方式，真空度为２ ５ｋＰａ㊂除非特殊说明，否则本文实验均在上述条件下实施㊂考虑到中试装置的数值波动问题，对于单因素变量进行考察时，使用同一批次实验的结果进行说明㊂渗透侧的气体通过液氮冷凝收集㊂进料浓度通过气相色谱仪测定，渗透侧浓度通过定容恒压法测定［１０］㊂每组实验重复３次，取平均值㊂用渗透通量（Ｊ）㊁渗透系数（Ｐ）㊁选择性（α）评价膜分离回收ＶＯＣｓ的性能，定义式见式（１） （３）［１１］㊂１ 气相色谱仪；２ 气体流量计；３ 料液罐；４ 膜组件；５ 冷阱；６ 真空泵㊂图１㊀蒸气渗透实验装置示意图Ｆｉｇ．１㊀ＳｃｈｅｍａｔｉｃｄｉａｇｒａｍｏｆｖａｐｏｒｐｅｒｍｅａｔｉｏｎｅｘｐｅｒｉｍｅｎｔｓＪ＝ｍＡΔｔ（１）Ｐｉｌ＝Ｊｉｐｉ０－ｐｉ１（２）α＝Ｐ（正己烷）Ｐ（Ｎ２)（３）式中：ｍ为渗透过膜后通过冷阱收集到的正己烷的质量，ｋｇ；Ａ为膜的有效膜面积，ｍ２；Δｔ为操作时间，ｈ；Ｊｉ为组分ｉ渗透通量；ｐｉ０和ｐｉ１分别为膜进料侧与膜渗透侧组分ｉ的分压，Ｐａ；ｌ为复合膜的厚度，ｍｍ；Ｐｉ为组分ｉ的渗透系数，下标ｉ分别为正己烷或Ｎ２㊂０５６南㊀京㊀工㊀业㊀大㊀学㊀学㊀报㊀（自然科学版）第４１卷㊀２㊀结果与讨论２．１㊀复合膜ＳＥＭ表征结果ＰＤＭＳ陶瓷复合膜ＳＥＭ分析结果如图２所示㊂由图２可见：ＰＤＭＳ陶瓷复合膜表面光滑致密，无缺陷；ＰＤＭＳ分离层与支撑体结合较紧密，膜厚度约为２μｍ㊂２．２㊀操作参数对膜性能的影响ＰＤＭＳ膜用于正己烷Ｎ２分离过程中，其分离机制遵循溶解扩散机制［１２］㊂其限速步骤通常发生在溶解过程，而溶解过程受到温度㊁浓度等因素的影响［１３］㊂因此，本文首先考察温度㊁浓度等条件对膜分离性能的影响规律㊂同时，在分离过程中，膜分离的驱动力是跨膜势能［１４］，其与真空度及原料侧压力有关，故本文需进一步研究跨膜压力对膜分离性能的影响规律㊂２．２．１㊀浓度的影响在３０ħ㊁进气流量为１ ２ｍ３／ｈ时，进料浓度对单根膜管的正己烷Ｎ２分离性能的影响如图３所示㊂从图３（ａ）中可以看出：随着正己烷摩尔分数（ｘ（正己烷））的升高，正己烷通量（Ｊ（正己烷））逐渐增大，Ｎ２通量（Ｊ（Ｎ２））逐渐减小㊂这是因为随着正己烷摩尔分数的升高，正己烷原料侧分压和与膜接触的机会都增加，增加了正己烷在膜内的溶解量和跨膜驱动力，引起通量的升高㊂Ｎ２通量下降是因为惰性气体与ＰＤＭＳ聚合物亲和性较差，其分离的速率限制步骤是扩散过程［１１］㊂随着正己烷摩尔分数的升高，优先吸附的正己烷会占据膜内传递通道，阻碍Ｎ２扩散［１５］；同时，随着正己烷摩尔分数的升高，Ｎ２原料侧分压随之降低，跨膜驱动力降低，导致Ｎ２通量随正己烷摩尔分数的升高而下降，最终引起分离膜选择性随着正己烷摩尔分数升高而升高（图３（ｂ））㊂这也说明了在ＰＤＭＳ陶瓷复合膜对正己烷Ｎ２的分离过程中，正己烷与Ｎ２之间存在相互竞争性㊂图２㊀ＰＤＭＳ陶瓷复合膜的ＳＥＭ照片Ｆｉｇ．２㊀ＳＥＭｉｍａｇｅｓｏｆＰＤＭＳ⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｓ图３㊀进料浓度对复合膜分离性能的影响Ｆｉｇ．３㊀Ｅｆｆｅｃｔｓｏｆｆｅｅｄｃｏｎｃｅｎｔｒａｔｉｏｎｏｎｔｈｅｓｅｐａｒａｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｏｆｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅ１５６㊀第５期宗传欣等：聚二甲基硅氧烷陶瓷复合膜的正己烷Ｎ２分离性能２．２．２㊀温度的影响图４为在正己烷进料摩尔分数为３％㊁进气流量为１ ２ｍ３／ｈ时，进料温度对复合膜正己烷Ｎ２分离性能的影响曲线㊂由图４（ａ）可见：随着温度的升高，正己烷通量逐渐降低，Ｎ２通量逐渐升高㊂当温度从２０ħ升高到６０ħ，Ｎ２通量升高了约３０％，而环己烷通量降低了约２５％㊂这是因为正己烷分离的速率限制步骤是溶解过程，而吸附溶解过程是放热过程［１６］，温度升高不利于正己烷在膜内的吸附，导致正己烷通量随温度升高而降低㊂而温度的升高会促进ＰＤＭＳ聚合物膜链段运动性，降低Ｎ２传递阻力，促进Ｎ２分子在膜内的传输［１７］，引起Ｎ２通量升高㊂最终导致膜分离选择性随着温度的升高而降低（图４（ｂ））㊂图４㊀进料温度对复合膜分离性能的影响Ｆｉｇ．４㊀Ｅｆｆｅｃｔｓｏｆｆｅｅｄｔｅｍｐｅｒａｔｕｒｅｏｎｔｈｅｍｅｍｂｒａｎｅｐｅｒｆｏｒｍａｎｃｅｏｆｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅ２．２．３㊀进料流量的影响进料流量影响复合膜处理效果和膜使用面积，对工业化应用具有重要的指导意义㊂因此，本文考察了进料流量对复合膜正己烷Ｎ２分离性能的影响，结果如图５所示㊂由图５可见：在３０ħ㊁正己烷进料摩尔分数为３％时，随着进料流量的升高，正己烷通量逐渐升高，而Ｎ２通量略微下降，导致选择性随着进料流量的升高而升高㊂随着进料流量的升高，正己烷Ｎ２混合物在膜组件内的停留时间变短，在进料浓度恒定的情况下，使得截留侧出口摩尔分数（ｘｒ）与进料口摩尔分数差距变小［１８］，渗透侧摩尔分数（ｘｐ）随之升高，如图６所示，选择性也随之升高㊂随着流量进一步升高，选择性趋于稳定，是因为膜分离能力趋于饱和，此时选择性不随进料流量的增加而改变［１８］㊂因此，本实验中１ ２ｍ３／ｈ为最优进料流量㊂图５㊀进料流量对复合膜分离性能的影响Ｆｉｇ．５㊀Ｅｆｆｅｃｔｓｏｆｆｅｅｄｖｏｌｕｍｅｏｎｔｈｅｓｅｐａｒａｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｏｆｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅ２．２．４㊀真空度的影响图７为在进料侧压力为０ １ ０ ４ＭＰａ㊁正己烷进料摩尔分数为３％㊁进气流量为１ ２ｍ３／ｈ时，跨膜驱动力对单根复合膜的正己烷Ｎ２分离性能的影响曲线㊂图８显示了在进料侧压力为０ １ ０ ４ＭＰａ时，环己烷和Ｎ２的跨膜驱动力随着渗透侧压力（ｐｐ）的变化㊂由图７（ａ）和７（ｂ）可以看出：随着下游侧真空压力的提高，正己烷的跨膜驱动力逐渐降２５６南㊀京㊀工㊀业㊀大㊀学㊀学㊀报㊀（自然科学版）第４１卷㊀图６㊀进料流量对渗透侧和截留侧摩尔分数的影响Ｆｉｇ．６㊀Ｅｆｆｅｃｔｓｏｆｆｅｅｄｖｏｌｕｍｅｏｎｔｈｅｒｅｓｉｄｕａｌｓｉｄｅａｎｄｐｅｒｍｅａｔｅｓｉｄｅｍｏｌａｒｆｒａｃｔｉｏｎ低，导致通量随之降低㊂Ｎ２通量下降较少，原因是Ｎ２的跨膜驱动力随下游侧真空压力变化不大（仅１０％），选择性随着渗透侧压力的升高明显降低（图８）㊂图７㊀渗透侧压力对复合膜分离性能的影响Ｆｉｇ．７㊀Ｅｆｆｅｃｔｓｏｆｐｅｒｍｅａｔｅｐｒｅｓｓｕｒｅｏｎｔｈｅｓｅｐａｒａｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｏｆｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅ由图７还可以看出：随着原料侧压力的升高，正己烷与Ｎ２的通量都升高，但是选择性却随着原料侧压力的升高逐渐降低㊂其原因是原料侧压力升高，驱动力增加，更多正己烷与Ｎ２渗透过膜，引起两者通量升高㊂但是由于Ｎ２分子动力学直径小［１９］，其在膜内的扩散阻力远小于正己烷在膜内的扩散阻力㊂因此，随着原料侧压力的升高，Ｎ２通量的增幅要大于正己烷通量的增幅［２０］，从而导致膜选择性随着原料侧压力的升高而降低㊂当真空度超过５ｋＰａ时，其分离因子与正己烷通量基本保持不变㊂由图８可以看出：当真空度超过５ｋＰａ时，正己烷跨膜驱动力变化趋缓，因此，其通量和分离因子变化也趋缓㊂但Ｎ２驱动力线性降低，导致其通量也近乎线性减小㊂选择性随真空度变化的具体原因可能还与膜厚度㊁组分性质等存在一定的内在联系，目前还在进一步研究中㊂２．２．５㊀长期稳定性ＰＤＭＳ陶瓷复合膜在分离正己烷Ｎ２过程中，ＰＤＭＳ分离层易受到正己烷溶胀破坏，浓度越高，影响越大㊂因此，本实验在正己烷摩尔分数为７ ８％㊁真空度为５ｋＰａ条件下，考察聚合物膜在实际工业化过程中膜分离性能的稳定性，结果如图９所示㊂从图９中可以看出：在６５ｄ的测试中，环己烷和Ｎ２的通量均保持稳定，选择性和渗透侧质量分数（ｗｐ）波动不大，膜的稳定性较好㊂说明尽管正己烷对膜具有溶胀性，但由于部分ＰＤＭＳ聚合物被无机陶瓷膜微孔所锚定，其溶胀性受到限制［２１］，一定程度上增强了ＰＤＭＳ聚合物对正己烷的抗溶胀性，提高了复合膜稳定性，具有较好的工业化应用性㊂３㊀结论１）正己烷与Ｎ２在分离膜传递过程中，存在相互竞争性，正己烷通量的提高会阻碍Ｎ２的渗透性；温度越高，正己烷通量越低，Ｎ２通量越大㊂当温度从２０ħ升高到６０ħ，Ｎ２的通量增加了约３０％，而环己烷通量降低了约２５％，最终导致选择性降低㊂２）流速增加，有利于膜分离性能的提高，但存在最优流速，本文以１ ２ｍ３／ｈ为最佳流速；原料侧压力升高可提高通量，但削弱选择性㊂３）真空度越低，通量越高，选择性越大㊂但真空度超过５ｋＰａ左右时，膜分离因子和通量变化幅度减缓㊂４）ＰＤＭＳ陶瓷复合膜分离在６５ｄ内运行稳定，表明复合膜具有优异的分离稳定性，这也为工业化应用提供了保证㊂３５６㊀第５期宗传欣等：聚二甲基硅氧烷陶瓷复合膜的正己烷Ｎ２分离性能图８㊀渗透侧压力对跨膜驱动力及其相对变化率的影响Ｆｉｇ．８㊀Ｅｆｆｅｃｔｓｏｆｐｅｒｍｅａｔｅｐｒｅｓｓｕｒｅｏｎｔｈｅｄｒｉｖｉｎｇｆｏｒｃｅａｎｄｉｔｓｃｈａｎｇｅｒａｔｉｏ图９㊀ＰＤＭＳ陶瓷复合膜的正己烷Ｎ２分离稳定性Ｆｉｇ．９㊀ＳｔａｂｉｌｉｔｙｏｆＰＤＭＳ⁃ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｆｏｒｓｅｐａｒａｔｉｏｎｏｆｎ⁃ｈｅｘａｎｅ⁃Ｎ２参考文献：［１］㊀张宇峰，邵春燕，张雪英，等．挥发性有机化合物的污染控制技术［Ｊ］．南京工业大学学报（自然科学版），２００３，２５（３）：８９．［２］㊀陆思华，白郁华，张广山，等．机动车排放及汽油中ＶＯＣｓ成分谱特征的研究［Ｊ］．北京大学学报（自然科学版），２００３，３９（４）：５０７．［３］㊀王震文．膜生物过滤技术净化工业废气中挥发性有机化合物性能研究［Ｄ］．上海：华东理工大学，２０１４．［４］㊀ＷＩＪＭＡＮＳＪＧ，ＢＡＫＥＲＲＷ．Ｔｈｅｓｏｌｕｔｉｏｎ⁃ｄｉｆｆｕｓｉｏｎｍｏｄｅｌ：ａｒｅｖｉｅｗ［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，１９９５，１０７（１／２）：１．［５］㊀ＢＡＫＥＲＲＷ，ＬＯＷＢＴ．Ｇａｓｓｅｐａｒａｔｉｏｎｍｅｍｂｒａｎｅｍａｔｅｒｉａｌｓ：ａｐｅｒｓｐｅｃｔｉｖｅ［Ｊ］．Ｍａｃｒｏｍｏｌｅｃｕｌｅｓ，２０１４，４７（２０）：６９９９．［６］㊀ＷＩＪＭＡＮＳＪＧ．Ｐｒｏｃｅｓｓｐｅｒｆｏｒｍａｎｃｅ＝ｍｅｍｂｒａｎｅｐｒｏｐｅｒｔｉｅｓ＋ｏｐｅｒａｔｉｎｇｃｏｎｄｉｔｉｏｎｓ［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，２００３，２２０（１／２）：１．［７］㊀吕利平，李航，李兵，等．变压精馏分离乙酸乙酯正己烷共沸物的动态特性［Ｊ］．高校化学工程学报，２０１８，３２（２）：４７８．［８］㊀ＬＩＵＧＰ，ＧＡＮＬ，ＬＩＵＳＮ，ｅｔａｌ．ＰＤＭＳ／ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｆｏｒｐｅｒｖａｐｏｒａｔｉｏｎｓｅｐａｒａｔｉｏｎｏｆａｃｅｔｏｎｅ⁃ｂｕｔａｎｏｌ⁃ｅｔｈａｎｏｌ（ＡＢＥ）ａｑｕｅｏｕｓｓｏｌｕｔｉｏｎｓａｎｄｉｔｓａｐｐｌｉｃａｔｉｏｎｉｎｉｎｔｅｎｓｉｆｉｃａｔｉｏｎｏｆＡＢＥｆｅｒｍｅｎｔａｔｉｏｎｐｒｏｃｅｓｓ［Ｊ］．ＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇａｎｄ４５６南㊀京㊀工㊀业㊀大㊀学㊀学㊀报㊀（自然科学版）第４１卷㊀Ｐｒｏｃｅｓｓｉｎｇ，２０１４，８６：１６２．［９］㊀ＺＨＯＵＨＬ，ＺＨＡＮＧＪＱ，ＷＡＮＹＨ，ｅｔａｌ．Ｆａｂｒｉｃａｔｉｏｎｏｆｈｉｇｈｓｉｌｉｃａｌｉｔｅ⁃１ｃｏｎｔｅｎｔｆｉｌｌｅｄＰＤＭＳｔｈｉｎｃｏｍｐｏｓｉｔｅｐｅｒｖａｐｏｒａｔｉｏｎｍｅｍｂｒａｎｅｆｏｒｔｈｅｓｅｐａｒａｔｉｏｎｏｆｅｔｈａｎｏｌｆｒｏｍａｑｕｅｏｕｓｓｏｌｕｔｉｏｎｓ［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，２０１７，５２４：１．［１０］㊀ＹＡＮＧＷＣ，ＺＨＯＵＨＬ，ＺＯＮＧＣＸ，ｅｔａｌ．ＳｔｕｄｙｏｎｍｅｍｂｒａｎｅｐｅｒｆｏｒｍａｎｃｅｉｎｖａｐｏｒｐｅｒｍｅａｔｉｏｎｏｆＶＯＣ／Ｎ２ｍｉｘｔｕｒｅｓｖｉａｍｏｄｉｆｉｅｄｃｏｎｓｔａｎｔｖｏｌｕｍｅ／ｖａｒｉａｂｌｅｐｒｅｓｓｕｒｅｍｅｔｈｏｄ［Ｊ］．ＳｅｐａｒａｔｉｏｎａｎｄＰｕｒｉｆｉｃａｔｉｏｎＴｅｃｈｎｏｌｏｇｙ，２０１８，２００：２７３．［１１］㊀ＭＵＬＤＥＲＭ．Ｂａｓｉｃｐｒｉｎｃｉｐｌｅｓｏｆｍｅｍｂｒａｎｅｔｅｃｈｎｏｌｏｇｙ［Ｊ］．ＡｎｇｅｗａｎｄｔｅＣｈｅｍｉｅＩｎｔｅｒｎａｔｉｏｎａｌＥｄｉｔｉｏｎ，２０１０，３６（１９）：２１２９．［１２］㊀ＳＯＭＭＥＲＳ，ＭＥＬＩＮＴ，ＦＡＬＣＯＮＥＲＪＬ，ｅｔａｌ．ＴｒａｎｓｐｏｒｔｏｆＣ６ｉｓｏｍｅｒｓｔｈｒｏｕｇｈＺＳＭ⁃５ｚｅｏｌｉｔｅｍｅｍｂｒａｎｅｓ［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，２００３，２２４（１／２）：５１．［１３］㊀董梦袁，申杰，刘公平，等．管式聚二甲基硅氧烷／陶瓷复合内膜的制备及其渗透汽化应用［Ｊ］．南京工业大学学报（自然科学版），２０１７，３９（３）：３４．［１４］㊀ＶＡＮＥＬＭ．Ｐｅｒｖａｐｏｒａｔｉｏｎａｎｄｖａｐｏｒｐｅｒｍｅａｔｉｏｎｔｕｔｏｒｉａｌ：ｍｅｍｂｒａｎｅｐｒｏｃｅｓｓｅｓｆｏｒｔｈｅｓｅｌｅｃｔｉｖｅｓｅｐａｒａｔｉｏｎｏｆｌｉｑｕｉｄａｎｄｖａｐｏｒｍｉｘｔｕｒｅｓ［Ｊ］．ＳｅｐａｒａｔｉｏｎＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ（Ｐｈｉｌａｄｅｌｐｈｉａ），２０１３，４８（３）：４２９．［１５］㊀ＰＩＮＮＡＵＩ，ＴＯＹＬＧ．Ｔｒａｎｓｐｏｒｔｏｆｏｒｇａｎｉｃｖａｐｏｒｓｔｈｒｏｕｇｈｐｏｌｙ（１⁃ｔｒｉｍｅｔｈｙｌｓｉｌｙｌ⁃１⁃ｐｒｏｐｙｎｅ）［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，１９９６，１１６（２）：１９９．［１６］㊀ＬＩＵＳＭ，ＴＥＯＷＫ，ＴＡＮＸＹ，ｅｔａｌ．ＰｒｅｐａｒａｔｉｏｎｏｆＰＤＭＳｖｉ⁃Ａｌ２Ｏ３ｃｏｍｐｏｓｉｔｅｈｏｌｌｏｗｆｉｂｒｅｍｅｍｂｒａｎｅｓｆｏｒＶＯＣｒｅｃｏｖｅｒｙｆｒｏｍｗａｓｔｅｇａｓｓｔｒｅａｍｓ［Ｊ］．ＳｅｐａｒａｔｉｏｎａｎｄＰｕｒｉｆｉｃａｔｉｏｎＴｅｃｈｎｏｌｏｇｙ，２００５，４６（１／２）：１１０．［１７］㊀ＳＵＷＡＮＤＩＭＳ，ＳＴＥＲＮＳＡ．Ｔｒａｎｓｐｏｒｔｏｆｈｅａｖｙｏｒｇａｎｉｃｖａｐｏｒｓｔｈｒｏｕｇｈｓｉｌｉｃｏｎｅｒｕｂｂｅｒ［Ｊ］．ＪｏｕｒｎａｌｏｆＰｏｌｙｍｅｒＳｃｉｅｎｃｅ（ＰｏｌｙｍｅｒＰｈｙｓｉｃｓ），１９７３，１１（４）：６６３．［１８］㊀ＫＵＪＡＷＳＫＡＡ，ＫＮＯＺＯＷＳＫＡＫ，ＫＵＪＡＷＡＪ，ｅｔａｌ．ＩｎｆｌｕｅｎｃｅｏｆｄｏｗｎｓｔｒｅａｍｐｒｅｓｓｕｒｅｏｎｐｅｒｖａｐｏｒａｔｉｏｎｐｒｏｐｅｒｔｉｅｓｏｆＰＤＭＳａｎｄＰＯＭＳｂａｓｅｄｍｅｍｂｒａｎｅｓ［Ｊ］．ＳｅｐａｒａｔｉｏｎａｎｄＰｕｒｉｆｉｃａｔｉｏｎＴｅｃｈｎｏｌｏｇｙ，２０１６，１５９：６８．［１９］㊀ＹＥＯＭＣＫ，ＬＥＥＳＨ，ＳＯＮＧＨＹ，ｅｔａｌ．ＶａｐｏｒｐｅｒｍｅａｔｉｏｎｓｏｆａｓｅｒｉｅｓｏｆＶＯＣｓ／Ｎ２ｍｉｘｔｕｒｅｓｔｈｒｏｕｇｈＰＤＭＳｍｅｍｂｒａｎｅ［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，２００２，１９８（１）：１２９．［２０］㊀ＳＩＮＧＨＡ，ＦＲＥＥＭＡＮＢＤ，ＰＩＮＮＡＵＩ．Ｐｕｒｅａｎｄｍｉｘｅｄｇａｓａｃｅｔｏｎｅ／ｎｉｔｒｏｇｅｎｐｅｒｍｅａｔｉｏｎｐｒｏｐｅｒｔｉｅｓｏｆｐｏｌｙｄｉｍｅｔｈｙｌｓｉｌｏｘａｎｅ（ＰＤＭＳ）［Ｊ］．ＪｏｕｒｎａｌｏｆＰｏｌｙｍｅｒＳｃｉｅｎｃｅ（ＰｏｌｙｍｅｒＰｈｙｓｉｃｓ），１９９８，３６（２）：２８９．［２１］㊀ＷＥＩＷ，ＸＩＡＳＳ，ＬＩＵＧＰ，ｅｔａｌ．Ｅｆｆｅｃｔｓｏｆｐｏｌｙｄｉｍｅｔｈｙｌｓｉｌｏｘａｎｅ（ＰＤＭＳ）ｍｏｌｅｃｕｌａｒｗｅｉｇｈｔｏｎｐｅｒｆｏｒｍａｎｃｅｏｆＰＤＭＳ／ｃｅｒａｍｉｃｃｏｍｐｏｓｉｔｅｍｅｍｂｒａｎｅｓ［Ｊ］．ＪｏｕｒｎａｌｏｆＭｅｍｂｒａｎｅＳｃｉｅｎｃｅ，２０１１，３７５（１／２）：３３４．（责任编辑㊀刘俊英）５５６㊀第５期宗传欣等：聚二甲基硅氧烷陶瓷复合膜的正己烷Ｎ２分离性能。