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.

Design and Fabrication of Ceramic Catalytic Membrane Reactors for Green Chemical Engineering Applications

Catalytic membrane reactors(CMRs),which synergistically carry out separations and reactions,are expected to become a green and sustainable technology in chemical engineering.The use of ceramic membranes in CMRs is being widely considered because it permits reactions and separations to be carried out under harsh conditions in terms of both temperature and the chemical environment.This article presents the two most important types of CMRs:those based on dense mixed-conducting membranes for gas separation,and those based on porous ceramic membranes for heterogeneous catalytic processes.New developments in and innovative uses of both types of CMRs over the last decade are presented,along with an overview of our recent work in this field.Membrane reactor design,fabrication,and applications related to energy and environmental areas are highlighted.First,the configuration of membranes and membrane reactors are introduced for each of type of membrane reactor.Next,taking typical catalytic reactions as model systems,the design and optimization of CMRs are illustrated.Finally,challenges and difficulties in the process of industrializing the two types of CMRs are addressed,and a view of the future is outlined.

Easy Fabrication of Dense Ceramic Membrane for Oxygen Separation

A combined EDTA-citrate complexing method was developed for the easy preparation of mixed oxygen-ionic and electronic conducting dense ceramic membrane for oxygen separation. The nea method takes the advantage of lower calcination temperature for phase formation. lower membrane sintering temperature and higher relative density over the standard ceramic method.

Numerical Study of Oil/Water Separation by Ceramic Membranes in the Presence of Turbulent Flow

Disposal of produced water during petroleum extraction causes serious environmental damage, hence the need to complete the water treatment before being disposed to environment within the criteria set established by environmental agencies in the countries. Ceramics membranes have been highlighted as a good device for separating oil/water. These act as a barrier to oil in the aqueous stream, because their essential properties for filtration, such as chemical inertness, biological stability and resistance to high temperatures. The limitation of the separation process is the decay of permeate flux during operation, due to concentration polarization and fouling. In this sense, this paper aims to evaluate numerically the feasibility of the process of separating oil/water by means of ceramic membranes in the presence of a turbulent flow induced by a tangential inlet. The results of the velocity, pressure and volumetric fraction distributions for the simulations different by varying the mass flow rate inlet and different geometric characteristics of the membrane are presented and analyzed.

Sprayed separation membranes: A systematic review and prospective opportunities

Membrane separation technology has been taken up for use in diverse applications such as water treatment,pharmaceutical,petroleum,and energy-related industries.Compared with the design of membrane materials,the innovation of membrane preparation technique is more urgent for the development of membrane separation technology,because it not only affects physicochemical properties and separation performance of the fabricated membranes,but also determines their potential in industrialized application.Among the various membrane preparation methods,spray technique has recently gained increasing attention because of its low cost,rapidity,scalability,minimum of environmental burden,and viability for nearly unlimited range of materials.In this Review article,we summarized and discussed the recent developments in separation membranes using the spray technique,including the fundamentals,important features and applications.The present challenges and future considerations have been touched to provide inspired insights for developing the sprayed separation membranes.

Preparation and Chiral Selectivity of BSA-Modified Ceramic Membrane

An affinity-transport system, containing porous ceramic membranes bound with bovine serum albumin （BSA） was used for chiral separation of racemic tryptophan. The preparation of BSA modified ceramic membrane included three steps. Firstly, the membrane was modified with amino group using silanization with an amino silane. Secondly, the amino group modified membrane was bound with aldehyde group using gluteraldehyde. Finally, BSA was covalently bound on the surface of the ceramic membrane. Efficient separation of racemic tryptophan was carded out by performing permeation cell experiments, with BSA modified, porous ceramic membranes.

Oily Water Treatment by Ceramic Membrane: Modeling and Simulation

The separation process of oily water using membranes has attracted the attention of researchers and engineers. The greater problem in the use of membrane separation process is the reduction in permeate flux due to clogged pores by oil deposition inside the membrane or by the effect of the concentration polarization. For this purpose, a theoretical study of a water/oil separation module was performed. This device consists of a tubular ceramic membrane provided with a rectangular inlet section. Numerical simulations were performed using Ansys CFX software to solve the mass and momentum conservation equations in the fluid and porous domains. Here was adopted the RNG k-ε turbulence model. The effect of the membrane porosity and the inlet velocity of the fluid mixture on the two-phase flow behavior inside the separation module were evaluated. Results of the volumetric fraction, velocity and pressure fields of the oil and water phases are presented and analyzed. The results indicate a higher oil concentration within the membrane for the cases of higher porosity, and that the inlet fluid mixture velocity does not substantially affect the velocity profile within the separation module. It is found that the maximum separation efficiency of the module was obtained with feed velocity of 40 m/s and membrane porosity of 0.44.

Tuning the membrane rejection behavior by surface wettability engineering for an effective water-in-oil emulsion separation

Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in oil.Herein we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil(W/O)emulsion.Silanes with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface wettabilities.While all the modified membranes exhibited excellent separation of the W/O without Span 80(surfactant),the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/O.The presence of Span 80 reduced the interfacial tension of water droplets,making them easier to deform and penetrate the modified membrane with the lowest surface energy.It reveals that engineering proper surface wettability is the key to separating the oil and water phases.Besides,the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.

Mixed-conducting ceramic–carbonate membranes exhibiting high CO2/O2 permeation flux and stability at high temperatures

This investigation demonstrates the feasibility to fabricate high quality ceramic–carbonate membranes based on mixed-conducting ceramics.Specifically,it is reported the simultaneous CO2/O2 permeation and stability properties of membranes constituted by a combination of ceramic and carbonate phases,wherein the microstructure of the ceramic part is composed,in turn,of a mixture of fluorite and perovskite phases.These ceramics showed ionic and electronic conduction,and at the operation temperature,the carbonate phase of the membranes is in liquid state,which allows the transport of CO32-and O2–species via different mechanisms.To fabricate the membranes,the ceramic powders were uniaxially pressed in a disk shape.Then,an incipient sintering treatment was carried out in such a way that a highly porous ceramic was obtained.Afterwards,the piece is densified by the infiltration of molten carbonate.Characterization of the membranes was accomplished by SEM,XRD,and gas permeation techniques among others.Thermal and chemical stability under an atmosphere rich in CO2 was evaluated.CO2/O2 permeation and long-term stability measurements were conducted between 850 and 940℃.The best permeation–separation performance of membranes of about 1 mm thickness,showed a maximum permeance flux of about 4.46×10^–7 mol·m^–2·s^–1·Pa^–1 for CO2 and 2.18×10^–7 mol·m^–2·s^–1·Pa^–1 for O2 at 940℃.Membranes exhibited separation factor values of 150–991 and 49–511 for CO2/N2 and O2/N2 respectively in the studied temperature range.Despite long-term stability test showed certain microstructural changes in the membranes,no significant detriment on the permeation properties was observed along 100 h of continuous operation.

Recent developments in polymeric nano-based separation membranes

Polymeric nanomaterials,which have tuneable chemical structures,versatile functionalities,and good compatibility with polymeric matrices,have attracted increasing interest from researchers for the construction of polymeric nano-based separation membranes.With their distinctive nanofeatures,polymeric nano-based membranes show great promise in overcoming bottlenecks in polymer membranes,namely,the trade-off between permeability and selectivity,low stability,and fouling issues.Accordingly,recent studies have focused on tuning the structures and tailoring the surface properties of polymeric nano-based membranes via exploitation of membrane fabrication techniques and surface modification strategies,with the objective of pushing the performance of polymeric nano-based membranes to a new level.In this review,first,the approaches for fabricating polymeric nano-based mixed matrix membranes and homogeneous membranes are summarized,such as surface coating,phase inversion,interfacial polymerization,and self-assembly methods.Next,the manipulation strategies of membrane surface properties,namely,the hydrophilicity/hydrophobicity,charge characteristics,and surface roughness,and interior microstructural properties,namely,the pore size and content,channel construction and regulation,are comprehensively discussed.Subsequently,the separation performances of liquid ions/molecules and gas molecules through polymeric nano-based membranes are systematically reported.Finally,we conclude this review with an overview of various unsolved scientific and technical challenges that are associated with new opportunities in the development of advanced polymeric nano-based membranes.

Dispersion of Titanium（Ⅳ） Oxide Nanoparticles in Mixed Matrix Membrane Using Octaisobutyl Polyhedral Oligomeric Silsesquioxane for Enhanced CO2/CH4 Separation Performance

Titanium(IV) oxide (TiO2) nanoparticles have been incorporated into mixed matrix membranes (MMMs) to improve gas separation performance. However, TiO2 nanoparticles tend to agglomerate due to high surface energy and van der Waals forces. This leads to precipitation which causes the formation of non-homogeneous MMM morphology. In this study, the effect of octaisobutyl polyhedral oligomeric silsesquioxane (POSS) addition on TiO2/polysulfone MMM was investigated. The aims are to enhance gas separation performance whilst preventing agglomeration of TiO2 nanoparticles. The results demonstrated that inclusion of POSS as dispersant increases MMMs’ CO2/CH4 selectivity and permeance, possibly due to less void formation and more evenly distributed pore structure. For example, synergistic addition of 5 wt% TiO2 and 5 wt% POSS increased the CO2/CH4 selectivity up to 390% compared to MMM without POSS. This is supported by elemental mapping of titanium which revealed that POSS successfully dispersed TiO2 nanoparticles and prevented aggregation. TiO2-POSS/PSf MMMs also retained their favorable thermal stability.

膜分离技术在饮用水处理的应用

随着人们对于饮用水水质要求的不断提高,特别是《生活饮用水卫生标准》(GB5479-2022)新标准的实施,饮用水处理已成为公众越来越关注的问题。膜技术作为一种新型的水处理技术发展迅速,本文综述了膜分离技术原理及分类,介绍了微滤、超滤、纳滤、反渗透膜分离技术的应用。

聚碳硅烷改性碳化硅陶瓷膜的制备及其性能研究

通过包覆法制备了聚碳硅烷包覆的碳化硅粉末,对其制备的生坯进行烧结,得到膜形态良好的碳化硅陶瓷膜。利用扫描电子显微镜、激光共聚焦显微镜、压汞仪和截留测试等手段分析了膜的形貌和截留性能。结果表明,聚碳硅烷在膜层的烧结过程中具有粘结作用,包覆量为5%时,膜层表面平整无裂缝,膜层形态较好。碳化硅初始骨料粒径为0.3μm,聚碳硅烷包覆量为5%,烧结温度为1750℃时,制备的膜层孔径为0.842μm,对100 nm微球截留率高达89%。研究表明,聚碳硅烷在碳化硅膜层形态及孔径控制方面应用优势明显。

耐有机溶剂型分离膜的制备及应用研究进展

有机溶剂的分离与纯化是近年来的研究热点,众多分离与纯化技术应运而生。耐有机溶剂膜分离技术具有高效节能、操作简便的优势,受到研究者们的普遍关注,在化工、环境、医药、纺织等领域具有广阔的应用前景。文中概括了耐有机溶剂型分离膜的分离技术与分类,阐述了耐有机溶剂型分离膜的制备方法,介绍了耐有机溶剂型分离膜的应用进展,并对耐有机溶剂型分离膜的发展趋势进行了展望。综述内容可为耐有机溶剂型分离膜的推广和应用提供策略支撑。

基于CPFD方法的生物质燃气旋风分离陶瓷膜一体化除尘器仿真

为缩短高温燃气除尘工艺,提高除尘效率,提出了一种耦合复合陶瓷膜组的一体化旋风除尘器。在温度为573 K的条件下对陶瓷膜的流动阻力进行了实验研究,考察了流量和压力对单个陶瓷膜过膜压降的影响,得到过膜压降与流速之间的关系式,基于计算颗粒流体力学(CPFD)方法模拟了除尘器内部的气固两相流动特性,探讨了生物质燃气除尘过程中内部颗粒的分布规律、速度和停留时间,探究了复合陶瓷膜组对除尘器压降和效率的影响。结果表明:在入口温度为573 K、压力为111325 Pa、进口气体积流量为7909 m^(3)/h的条件下,较之无陶瓷膜组的除尘器,一体化除尘器内部粉尘颗粒的停留时间更长,其对粉尘颗粒捕集效率更高,颗粒聚集性能更好,除尘效率从91.2%提升至99.7%,然而总体压降增大了78 Pa。

混合导体陶瓷膜及其膜反应器的研究进展

重点介绍了用于氧气、氢气以及二氧化碳分离的混合导体陶瓷膜和对应的典型膜反应器,分别关注了不同致密陶瓷膜的分离机理、材料、结构和膜反应器的应用实例。对混合导体陶瓷膜及膜反应器的应用前景和发展方向进行了展望。

膜分离技术在工业废水零排放工艺中的应用研究

为应对我国工业快速发展带来的水资源短缺问题,废水零排放工艺成为废水处理领域关注的热点,膜分离技术以优越的分离、纯化等性能在诸多领域得到了广泛的应用。介绍并总结了膜分离技术的原理、分类及发展现状,重点探讨其在废水零排放工艺中的研究进展与工程应用实例,最后对膜分离技术在废水零排放工艺中的发展进行了展望。

浅谈膜分离技术在生物化工方面的应用

膜分离技术被称为21世纪最具发展前景的高新技术之一,目前这项技术在许多领域中已有着广泛的应用。介绍膜分离技术的主要类型及优势,综述其在生物化工方面的应用现状,应用实践表明,膜分离技术可有效解决传统分离技术在产品分离过程中存在的工艺条件要求高、过程复杂、周期长、能耗大、易造成二次污染等问题,明显提升生物化工产品的收率和品质。同时,也对膜分离技术在生物化工应用中存在的问题提出了优化建议。

不同孔径陶瓷膜硅烷改性及油水分离性能研究

具有低表面能的疏水陶瓷膜常用于含水油液分离,而渗透通量的提高是提升膜分离过程经济性的关键.本文通过有机硅烷接枝改性制备疏水陶瓷膜,研究硅烷改性对不同孔径陶瓷膜结构及油水分离性能的影响。以孔径为1 000 nm、100 nm、10 nm的3种陶瓷膜为研究对象,考察不同孔径陶瓷膜硅烷化改性前后膜表面微观形貌、润湿性及渗透阻力的变化,评价3种孔径疏水陶瓷膜在溶剂、酸碱等环境下的稳定性,并将3种孔径硅烷改性的陶瓷膜用于油包水乳液分离.结果表明,孔径越小的膜硅烷化改性后渗透阻力增幅越大,尤其是当孔径达到10 nm,改性前后渗透阻力相差近3倍;原膜孔径对改性膜润湿性影响不大,且均表现出良好的耐溶剂性、耐酸碱性.低压高流速的操作方式有利于提高改性膜通量;对于水含量1 000μL/L的W/O乳液,3种改性膜对水的截留率均超过93%,渗透液水含量低于70μL/L,其中1 000 nm改性膜通量最高,达375 L/(m^(2)·h),而10 nm膜更不易被污染;对于水含量10%(体积分数)的W/O乳液,1 000 nm改性膜污染非常严重,通量迅速下降为14.1 L/(m^(2)·h),而100 nm改性膜污染程度较小,通量较高.

M/PDMS复合膜的制备及其CO_(2)/N_(2)分离性能

通过梯度烧结法制备得到莫来石陶瓷膜,将不同相对分子质量的硅橡胶类聚合物聚二甲基硅氧烷(PDMS)按不同比例进行混合,涂覆在莫来石陶瓷膜表面以覆盖陶瓷膜表面孔径,得到M/PDMS复合膜,PDMS提高了M/PDMS复合膜对CO_(2)的吸附性能和CO_(2)/N_(2)的选择性。通过XRD、SEM对莫来石陶瓷膜和M/PDMS复合膜进行结构性能表征,并采用自制气体分离装置测试膜对单一气体的渗透速率并计算CO_(2)/N_(2)的分离性能。结果表明,在室温条件及0.2 MPa的操作压力下,M/PDMS复合膜对CO_(2)的渗透速率高达2300 GPU;CO_(2)/N_(2)选择性为1.52。