用于VOC回收的PVDMS-Al2O3中空纤维复合膜

Sorption isotherm of chloroform in polyvinyl dimethylsiloxane （PVDMS） polymer film was measured via the gravimetric method, and this film was confirmed experimentally to be good membrane material to recover chloroform from gas stream with high sorption capacity. A new PVDMS-Al2O3 composite hollow fibre membrane was further prepared by coating a PVDMS film on the outer surface of Al2O3 hollow fibre porpous substrate prepared by a dry/wet phase inversion method. Microstructure of the composite membranes was examined by scanning electron microscopy （SEM）, indicating the PVDMS coating layer was uniform, free of defects, and around 15μm thick. Performance of the PVDMS-Al2O3 composite hollow fibre membranes for chloroform recovery was investigated. By comparing the experimental data that derived from a mathematical model, the permeabilities of chloroform and nitrogen in the PVDMS polymer membrane were obtained. The effects of temperature and feed flow rate on the chloroform recovery and permeate concentration were investigated both experimentally and theoretically.     

用于甲烷偶联的SrCe0.95Yb0.05O3-α中空纤维膜反应器建模

Proton-hole mixed conductor, SrCe0.95Yb0.05O3-α(SCYb), has the potential to be used as a membrane for dehydrogenation reactions such as methane coupling due to its high C2-selectivity and its simplicity for fabricating reactor systems. In addition, the mixed conducting membrane in the hollow fibre geometry is capable of providing high surface area per unit volume. In this study, mechanism of methane coupling reaction on the SCYb membrane was proposed and the kinetic parameters were obtained by regression of experimental data. A mathematical model describing the methane coupling in the SCYb hollow fibre membrane reactor was also developed.With this mathematical model, various operating conditions such as the operation mode, operation pressure and feed concentrations affecting performance of the reactor were investigated. The simulation results show that the cocurrent flow in the reactor exhibits higher conversion of methane and higher yield of ethylene compared to the countercurrent flow. In order to achieve the highest C2 yield, especially of ethylene, pure methane should be used as feed and the operating pressure be 300 kPa. Air can be used as the source of oxygen for the reaction and it soptimum feed velocity is twice of the methane feed velocity. The air pressure in the lumen side should be kept the same as or slightly lower than the vressure of shell side.     

PVDF-TiO2复合中空纤维膜的制备与表征

将纳米二氧化钛(TiO₂)粒子与4类制膜添加剂复配处理,采用相转化法制备聚偏氟乙烯(PVDF)-TiO₂复合中空纤维膜,讨论了纳米TiO₂粒子对复合膜结构和性能的影响。通过扫描电子显微镜、X射线衍射、能谱分析、热重分析、拉伸试验、接触角测定和超滤实验分别表征了复合膜的微观孔结构、晶相结构和复合均匀性、热稳定性、机械性能、亲水性、超滤性能以及抗污染性能。结果表明：通过添加TiO₂粒子复配添加剂,复合膜的性能得到有效改善。复配添加剂中w(TiO₂)为2%(占PVDF固含量的质量分数)时,纯水通量由348 L/(m²·h)提高至377 L/(m²·h),牛血清蛋白截留率由68%提高至90%,断裂强度和抗污染性能提高,复合膜综合性能优异。     

单外皮层PES中空纤维气体分离膜制备的研究

以聚醚砜(PES)作膜材料,N-甲基吡咯烷酮(NMP)为溶剂,乙醇(Ethanol)作非溶剂,NMP-Water为芯液,获得PES/NMP/Ethanol铸膜液[m(PES)∶m(NMP)∶m(Ethanol)=35∶57∶8],采用相转化法制备了PES中空纤维气体分离不对称膜,研究了保存时间、硅橡胶种类、芯液浓度、芯液流量和凝胶温度等对PES中空纤维膜O2/N2渗透性能的影响。同时,分析了单外皮层PES中空纤维气体分离膜的结构,讨论了PES中空纤维气体分离膜的机械性能。当芯液组成的m(NMP)∶m(H2O)=86∶14和凝胶温度17℃时,涂3%硅橡胶A后的PES中空纤维气体分离膜气体分离性能如下:αO2/N2=6.68,JO2=2.26GPU,JN2=0.33GPU。     

硅橡胶膜用于植物油/己烷胶团中溶剂回收的研究

Traditional solvent recovery in the extraction step of edible oil processing is distillation, which consumes large amounts of energy. If the distillation is replaced by membrane process, the energy consumption can be reduced greatly. In this work, two kinds of membrane, PDMS (polydimethylsiloxane) composite membrane and Zeolite filled PDMS membrane were prepared, in which asymmetric microporous PVDF (polyvinylidenefluoride) membrane prepared with phase inversion method was functioned as the microporous supporting layer in the flat-plate composite membrane. The different function compositions of the PDMS/PVDF com-posite membranes were characterized by reflection Fourier transform infrared (FTIR) spectroscopy. The surface and section of PDMS/PVDF composite membranes were investigated by scanning electron microscope (SEM). The PDMS NF (nanofiltration) membranes were then applied in the recovery of hexane from soybean oil/hexane miscellas (1︰3, mass ratio). The effects of pres-sure (0.5-1.5 MPa), cross-linking temperature and PDMS layer thickness on membrane performances were investigated. The results indicated that both two kinds of NF membranes were promising for solvent recovery, and zeolite filled in PDMS NF membrane could enhance the separation performance.     

Separation of Phenol from Aqueous Streams by a Composite Hollow Fiber Based Pervaporation Process Using Polydimethyl siloxane (PDMS)/Polyether-Block-Amide (PEBA) as Two-Layer Membranes

Abstract

In order to simultaneously achieve both high permselectivity and permeability (flux) for the recovery of aromatic compounds such as phenol from aqueous streams, a composite organophilic hollow fiber based pervaporation process using PDMS/PEBA as two-layer membranes has been developed. The process employed a hydrophobic microporous polypropylene hollow fiber, having thin layers of silicones (PDMS) and PEBA polymers coating on the inside diameter. The composite membrane module is used to investigate the pervaporation behavior of phenol in water in a separate study; and that of a mixture of phenol, methanol, and formaldehyde in an aqueous stream (a typical constituent of wastewater stream of phenol-formaldehyde resin manufacturing process) in another study. The fluxes of phenol and water increase relatively linearly with increasing concentration especially at low feed concentration, and exhibit a near plateau with further increase in concentration. As a result, the phenol/water separation factor decreases as the feed concentration increases. Significant improvement in phenol/water separation factor and phenol flux is achieved for this two-layer (PDMS/PEBA) membranes as compared to that achieved using only PDMS membrane. The phenol and water fluxes and the separation factor are highly sensitive to permeate pressure as all decrease sharply with increase in permeate pressure. For this membrane, an increase in temperature increases the separation factor, and also permeation fluxes of phenol and water. An increase in feed-solution velocity does not have a significant effect on phenol and water fluxes, and also on the separation factor at least within the range of the feed-solution velocity considered. In the study of pervaporation behavior of a typical constituent of wastewater stream of phenol-formaldehyde resin manufacturing process, phenol permeation shows a much higher flux and a higher increase in flux with increase in concentration is also exhibited as compared to that exhibited by methanol permeation. This thus indicates that the membrane is more permeable to phenol than to methanol and formaldehyde.     

硅橡胶—玻璃中空纤维富氧膜的制备

以玻璃粉为基膜材料,通过溶液纺丝技术制备了玻璃中空纤维基膜。将其置于一定浓度的硅橡胶(PDMS)溶液中浸渍,得到了硅橡胶-玻璃中空复合膜。利用电子扫描显微镜、红外光谱仪、X-射线光电子能谱仪分析复合膜的微观形态和元素变化。探究了浓度、浸渍次数对硅橡胶-玻璃中空复合膜富氧性能的影响。     

活性炭纤维吸附回收尾气中的环己烷

介绍了利用活性炭纤维的特性，以及用其吸附回收尾气中环己烷的工艺流程，通过与颗粒活性炭吸附工艺比较，指出采用该新工艺吸附回收有机尾气具有投资少、运行费用低、操作安全、设备运行稳定等优越性。     

纳米Al2O3粒子对PVDF中空纤维膜的改性研究

文章介绍了在聚偏氟乙烯铸膜液中添加了无机钠米Al2O3粒子,采用相转化法制备了Al2O3/PVDF复合中空纤维膜。使用电镜对膜的微观结构进行了分析,初步研究了无机粒子在膜孔形成的过程中所起的作用和机理。并且对膜的孔隙率、最大孔径、力学性能和截留率进行了分析。结果表明复合膜的性能与纯PVDF膜的相比有显著提高,最大孔径从0.75μm降至0.39μm,水通量和截留率分别从10.09 L/m2.h和19.12%提高到28.25 L/m2.h和71.00%,断裂应力从3.09 MPa提高到3.41 MPa。     

纳米结构TiO2微孔复合膜的研制

本文用异丙醇钛经溶胶－凝胶过程制得了二氧化钛粒子溶胶，确定成膜时的烧结温度，制得的膜经SEM测试具有典型的不对称结构，用压汞法测量孔径分布在2．7－11nm范围内。     

Ceramic Supported PDMS and PEGDA Composite Membranes for CO2 Separation

Composite membranes have attracted increasing attentions owing to their potential applications for CO2 separation. In this work, ceramic supported polydimethylsiloxane （PDMS） and poly （ethylene glycol） diacrylate （PEGDA） composite membranes were prepared. The microstructure and physicochemical properties of the compos- ite membranes were characterized. Preparation conditions were systematically optimized. The gas separation performance of the as-prepared membranes was studied by pure gas and binary gas permeation measurement of CO〉 N2 and H〉 Experiments showed that PDMS, as silicone rubber, exhibited larger permeance and lower separation factors. Conversely, PEGDA composite membrane presented smaller gas permeance but higher ideal selectivity for CO2/N2. Compared to the performance of those membranes using polymeric supports or freestanding membranes, the two kinds of ceramic supported composite membranes exhibited higher gas permeance and acceptable selectivity. Therefore, the ceramic supported composite membrane can be expected as a candidate for CO2 separation from light gases.     

中空纤维PVA/PAN复合膜填料的乙醇水溶液精馏性能

以乙醇/水溶液为分离对象,中空纤维PVA/PAN复合膜作为精馏填料,考察了不同膜组件的传质分离效率。实验结果表明:各种组件的分离效率均随塔釜加热功率的增加而减小;和大多数中空纤维膜接触器一样,其总传质系数Ky随中空纤维膜组件填充密度φ的增加而减少;相比于传统精馏填料而言,用中空纤维膜做精馏填料分离乙醇水溶液的分离效果更好,可以在常规填料不能操作的液泛线以上进行操作。当塔釜加热功率为120 W,45根中空纤维膜封装在内径为1.6 cm玻璃管中的传质单元高度(HTU)为5.64 cm。     

Optimization of Membrane Process for Methane Recovery from Biogas

Including biogas, methane (CH₄) could be used as one of the important energy sources. In this research, the membrane separation process took place to recover purified CH_4, such as hydrogen sulfide (H₂S). The Polyethersulfone (PES) Hollow Fiber Membranes (HFM) was prepared by the dry-wet phase inversion technique. The simulation program using MATLAB was evaluated by utilizing the information from experimental results of a well-designed process. From the simulation program, the process that meets the specified conditions was designed. The three-stage process that has a membrane area of 454.3 m² recovered 91.3% of CH₄ in the feed of 250 l/min at 5 kg_f/cm² and 30°C. The membrane area and the recovery of CH₄ decreases as the operating process increases.     

Performance Comparison of Different Separation Systems for H2 Recovery from Catalytic Reforming Unit Off‐Gas Streams

The performance of pressure swing adsorption (PSA), membrane separation, and gas absorption systems for H₂ recovery from refinery off‐gas stream was studied by simulation‐based data. The PSA process was simulated using adsorbents of silica gel and activated carbon for removing heavy and light hydrocarbons. The mole fraction profiles of all components and the relationship between hydrogen purity and recovery as a function of feed pressure were examined. The solution‐diffusion model was applied for modeling and simulation of a one‐stage membrane process. The gas absorption process with a tower tray was simulated at sub‐zero temperature and the correlation between hydrogen purity and recovery as a function of tower pressure and temperature was evaluated at different solvent flow rates.     

碳纤维复合材料镜筒研制

本文对一种高比强度、高比刚度、低热膨胀系数的高性能复合材料空间光学结构碳纤维复合材料镜筒的设计、工艺制作、试验等进行了研究,采用缠绕加铺放的组合工艺技术制作了样件,经过对样件的测试和检测,各项性能指标均达到了设计要求,轴向热膨胀系数为0．36×10^-6／℃,较铝合金结构可以减重42．8％。     

Recovery of Copper Ions from Wastewater by Hollow Fiber Supported Emulsion Liquid Membrane

Recovery of copper ions from wastewater using a hollow fiber supported emulsion liquid membrane (HFSELM) was studied with LIX984N as carrier, kerosene as diluents, and sulfuric acid solution as strippi...     

气体分离用聚砜中空纤维膜的活化涂敷技术

主要探讨了一些表面活性剂对气体分离用聚砜中空纤维膜表面涂敷上的作用。结果表明 ,其中TO 80对提高H2 /N2 分离系数的效果最佳。     

中空纤维膜结构对脱除烟气中CO_2影响的数值研究

相对于传统的脱碳方法,中空纤维膜脱除烟气中CO2是一种清洁、高效的技术方法。运用有限单元法建立了一个疏水性中空纤维膜脱除烟气中CO2的二维模型,考察了膜丝直径、壁厚、孔隙率、曲折因子、纤维膜根数、膜柱内径和长度等方面对CO2脱除率的影响,模型结果与实验值相符。结果表明四种吸收剂的脱除率从大到小依次为EDAMEADEAAMP。当液速为0.1 m·s–1、气速0.211 m·s–1、操作压力为0.1 MPa时,减小曲折因子、膜丝壁厚和膜柱内径,增大孔隙率、膜丝内径与膜柱长度都有利于膜吸收CO2。     

陶瓷支撑的有机复合膜及其在渗透汽化中的应用(英文)

Pervaporation(PV),as an environmental friendly and energy-saving separation technology,has been received increasing attention in recent years.This article reviews the preparation and application of macroporous ceramic-supported polymer composite pervaporation membranes.The separation materials of polymer/ceramic composite membranes presented here include hydrophobic polydimethylsiloxane(PDMS) and hydrophilic poly(vinyl alcohol)(PVA),chitosan(CS) and polyelectrolytes.The effects of ceramic support treatment,polymer solution properties,interfacial adhesion and incorporating or blending modification on the membrane structure and PV performance are discussed.Two in-situ characterization methods developed for polymer/ceramic composite membranes are also covered in the discussion.The applications of these composite membranes in pervaporation process are summarized as well,which contain the bio-fuels recovery,gasoline desulfuration and PV coupled proc-ess using PDMS/ceramic composite membrane,and dehydration of alcohols and esters using ceramic-supported PVA or PVA-CS composite membrane.Finally,a brief conclusion remark on polymer/ceramic composite mem-branes is given and possible future research is outlined.