多孔陶瓷分离膜

多孔陶瓷膜由于其优良的耐高温、耐腐蚀、耐微生物侵蚀等性质，近年来被快速地应用于分离领域。本文介绍其制备方法、性能测定及应用前景。     

Electrical Properties of Porous Titania Ceramic Humidity Sensors

Ceramic humidity sensors made with pure TiO₂ powder as the starting material are investigated. The sensor can be reversibly operated without repeated high-temperature thermal desorption, and the conductance versus relative humidity (rh) sensitivity of the sensor is more than 4 orders of magnitude in the range ∼15% to 95% rh at 400 Hz and 25°C. The sensor can be polarized similar to electrolytes in the charging process, and the degree of polarization is enhanced with increasing rh. The conduction carriers of the sensor in the humid atmosphere are ions and electrons, and ions are the dominant conduction carrier. The relative dielectric dispersion k'(ω) is almost proportional to ω^−1.84 for rh ∼50% to 95% at low frequencies, where ω is the angular frequency. An inductive effect is also observed in a low-humidity atmosphere, which implies desorption of water vapor with the regeneration of the adsorption sites.     

反胶团法制备氧化钛超滤膜的研究

采用新型的反胶团法制备了氧化钛超滤膜。实验以钛酸丁脂、水、环己烷、异戊醇及表面活性剂Span-80等为原料,通过控制水量制得三种粒径分布的氧化钛反胶团微乳液。TEM照片表明,TiO2反胶团粒子随着[H2O]/[Span-80]由13.9增加到55.5而增大,但当[H2O]/[Span-80]增加到110.9时TiO2反胶团粒子反而减小。BET法结果与TEM照片一致,而且表明[H2O]/[Span-80]为110.9的TiO2反胶团微乳液所制得的无支撑膜孔径分布最窄、最可几孔径约为4.5nm。采用该种微乳液所制得的氧化钛支撑膜的最可几孔径约为16nm, 纯水渗透率为1.57×10-4m3(m2sMPa)-1;常温下N2、H2渗透率分别为4.3mol (m2sMPa)-1和14.1mol(m2sMPa)-1,表明所得TiO2分离层较完整。     

Porous Titania Ceramic Prepared by Mimicking Silicified Wood

A porous titania ceramic with a woodlike microstructure that was analogous to silicified wood was prepared. The production of "titanified wood" was performed using the following process: (i) introduction of titanium tetraisopropoxide into wood materials via vacuum infiltration, (ii) hydrolysis of the titanium tetraisopropoxide in the cell structure to form a titania gel, and (iii) firing at a temperature of 600°–1400°C in air. The resulting titania ceramic had the same external and internal forms of the original wood.     

聚四氟乙烯微孔膜的研究进展

聚四氟乙烯微孔膜具有化学性质稳定、透光率高、透水率高、耐高温、抗腐蚀等优点,应用非常广泛。本文综述了聚四氟乙烯微孔膜的制备方法及在电学、医学、化工、服装等多个领域的最新应用,并指出了其存在的问题及今后的发展方向。     

萃取-膜蒸馏法处理钛白废酸的研究

提出了三异辛胺-仲辛醇-航空煤油体系萃取硫酸与减压膜蒸馏浓缩相结合的钛白废酸治理新方案。对萃取工艺参数、膜蒸馏浓缩稀硫酸的基本规律及萃取回收硫酸的浓缩程度进行了研究。结果表明:1.49mol·L-1的钛白废酸经8级萃取和6级反萃取,酸回收率可达92.15%,稀硫酸浓度为1.21mol·L-1,再经减压膜蒸馏浓缩可得到10.82mol·L-1(质量分数67.3%)的硫酸,达到了返回钛白生产循环使用的要求。     

Ceramic/Polyaniline Composite Porous Membranes

Ceramic/polyaniline composite porous membranes are successfully made by diffusing ammonium peroxydisulfate and aniline into inorganic membrane disks. The ceramic disks are fabricated by mixing CMC, water, kaolin and alumina followed by the processes of drying, milling, sieving, pressing at 4000 pounds, and firing. The pore size of the disk is approximately 1 m.When the concentration of the oxidant is 0.25 M and that of the monomer is 1 M, the incorporation of polyaniline into the ceramic disks levels off after about 40 hours. The maximum incorporation percentage is approximately 4.86 wt% (0.18 g of polymer/3.7 g of disk). Characterizations of the ceramic disk and its composites include N2-flow tests, solubility tests, BET, SEM, OM and acid diffusion studies. Nitrogen-flow tests indicate that the incorporated polyaniline is structurally unstable. However, after applying N2 gas of 23 psig for about 40 min, no further degradation is observed in these composite membranes even under 40 psig of N2 gas. BET shows that the surface area of the composite is greater than that of the ceramic disk. SEM reveals that polyaniline is grown on the surface of the pores of the ceramic disks. Time constants, corresponding to the time when the pH value reaches 36.8% of the initial value, are estimated from the results of acid diffusion studies. The magnitude of the time constant is in the following order: ceramic/Peani base > ceramic/Peani salt > ceramic/Pani base > ceramic/Pani salt > plain ceramic.     

玻璃分离膜的制备,性能与应用

本文综述了近年来玻璃分离膜的制备工艺,性能及应用研究方面的进展,介绍了玻璃分离膜的主要制备方法,影响玻璃膜性能的因素,并对玻璃分离膜的应用及发展前景进行了讨论。append     

聚四氟乙烯拉伸微孔膜的结构与性能

通过挤出、压延和拉伸等工序制备了聚四氟乙烯微孔膜，采用扫描电镜（SEM）分析了微孔膜的微观结构；采用差示扫描量热法（DSC）和广角X衍射（WXRD）表征了拉伸前后聚四氟乙烯结晶度的变化；研究了拉伸温度、拉伸倍率和拉伸速率对微孔膜力学性能的影响。结果表明：聚四氟乙烯微孔膜具有小岛状结点和与拉伸方向平行的微细纤维组成的微观结构；拉伸使PTFE的结晶度显著降低；拉伸工艺是制备微孔膜的关键因素，拉伸温度220～320℃，拉伸倍率为8倍时，微孔膜的最大拉伸强度可达8．5MPa；此外较大的拉伸速率可获得尺寸分布更均匀的微孔。     

浅谈多孔陶瓷材料及其过滤技术

陶瓷过滤器以其独特的功能特性,在分离、净化领域中已成为一种不可替代的产品。本文根据多孔陶瓷过滤技术的发展变迁,对多孔金属滤材与多孔陶瓷滤材的性能进行了比较,阐述了多孔陶瓷滤材过滤元件的性能指标及过滤原理,介绍了多孔陶瓷及过滤器的应用现状,同时指出了多孔陶瓷材料过滤技术的发展前景。     

Synthesis and Characterization of Nano-Composite Alumina–Titania Ceramic Membrane for Gas Separation

A ceramic composite membrane was prepared using a commercial titania ceramic membrane coated by alumina oxide via a sol–gel technique where polyvinyl alcohol (PVA) was used as a binder. The characteristic of the membrane was analyzed in terms of the effect of PVA concentration and sintering temperature on viscosity, pore size, density, porosity and surface area of the membrane. Two vol% of PVA solution containing 4 g of PVA in 100 mL of water was adequate to achieve an appropriate porosity level to avoid cracks on the gel layer. Sol viscosity and pore size of the membrane essentially increased when the PVA concentration was increased. The density of the membrane increased as the sintering temperature increased. The porosity level however, decreased when the temperature was increased. The composite membrane was further characterized in terms of permeability of pure gas at low-temperature region (301 K) where an experimental platform has been developed to perform the permeability studies.     

陶瓷膜技术及应用现状

介绍了国际上陶瓷膜技术的开发和产业化进展情况，总结了陶瓷膜技术的重要应用，最后阐述了我国陶瓷膜的生产情况和标准进展。     

Planar,Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

Porous, silicon carbonitride‐based ceramic support structures for potential membrane and catalysis applications were generated from a preceramic polysilazane precursor in combination with spherical, ultrahigh‐molecular weight polyethylene microparticles through a sacrificial filler approach. A screening evaluation was used for the determination of the impact of both porogen content and porogen size on pore structure, strength, and permeability characteristics of planar specimens. By optimizing both the composition as well as cross‐linking parameters, maximum characteristic biaxial flexural strengths of 65 MPa and porosities of 42% were achieved. The evolution of an interconnected, open‐pore network during thermal porogen removal and conversion of the preceramic polymer led to air permeabilities in the order of 10^?14 m². The materials were further exposed to long‐term heat treatments to demonstrate the stability of properties after 100 h at 800°C in oxidizing, inert, and reducing environments. The determined performance, in combination with the versatile preparation method, illustrates the feasibility of this processing approach for the generation of porous ceramic support structures for applications at elevated temperatures in a variety of fields, including membrane and catalysis science.     

添加剂对多孔陶瓷载体氧化铝涂层的影响

在以SB粉为原料,HNO3为解胶剂制得的稳定AlOOH溶胶中加入添加剂(PEG、PVA),对多孔陶瓷载体进行了表面涂层.考察了添加剂对AlOOH溶胶粘度的影响;BET法测定了AlOOH溶胶中加入添加剂后多孔陶瓷载体氧化铝涂层比表面积的变化;由SEM照片观察多孔陶瓷载体涂层前后表面和断面的形貌;超声波振荡检测了氧化铝涂层的附着牢固度.结果表明,在AlOOH溶胶中加入一定量的添加剂可以使溶胶的粘度增加,提高溶胶在载体表面的附着力;制备的多孔陶瓷载体氧化铝涂层均匀、牢固且比表面积增大.但加入过量的添加剂,会导致AlOOH溶胶胶凝化.     

Diamond Coating of Porous Silicon

Diamond coatings on porous silicon (PS) samples have been obtained by the hot-filament chemical vapor deposition(CVD) technique. We focused our attention on the coating morphology, showing experimentally that high quality diamond coatings may be produced with the PS sample kept at 710°C. The deposited patterns consist of polycrystalline grains with a plane interface with the PS layer.At 790°C, the quality of the coating is improved but the PS layer becomes damaged, and at 650°C the coating consists of diamond-like carbon particles. Besides the temperature, other factors such as the porosity, roughness and chemical activity of the PS layer deserve attention. We observed that one of the limiting factors of the deposition process was the high nucleation time. Two nucleation mechanisms are involved in the growth process. The first nucleation mechanism occurs on the top of the sharp PS features, subsequently to the nucleation a superficial film, and then a second nucleation mechanism occurs over this surface, which allows the growth process to continue. We also observed the presence of ablue-shift in the luminescence spectra following the coating.     

多孔分离膜材料改性研究进展

膜是膜技术的核心.在对废水进行膜分离过程中,对膜材料的性能往往存在着几个截然不同的要求,既要求有高的水通量,又要求有高的选择性,且具备良好的抗污染性能.因此开发具有某些需要的性能的膜分离材料是解决水污染治理中膜分离技术应用问题的关键.本文综述了当前国内外膜分离材料改性研究的主要方法和研究进展,提出通过共混合金的方法对膜材料进行改性是提高膜材料分离性能的捷径.     

ZrO2载体膜的表征

文章采用自行搭建的液-液排除法装置测定了ZrO2载体膜孔径及孔径分布,并考察了不同浸润-渗透体系对孔径测定结果的影响,不同浸润剂的测定结果具有一致性。使用界面张力小的浸润-渗透体系,得到的孔径分布也偏小。液-液排除法的结果与SEM法进行比较,二者具有很好的一致性。     

草酸溶液中多孔氧化铝的制备及机理研究

以草酸溶液为电解质,采用两次电化学阳极氧化法制备氧化铝有序多孔膜,研究了不同阶段孔洞的形态结构以及孔洞的排布,发现自组织过程主要是在第一次阳极氧化的过程中实现的,第二次阳极氧化只是在第一次的基础上实现孔的有序定向生长。     

陶瓷分离膜支撑体制备技术研究进展

介绍了几种无机陶瓷支撑体的制备方法,评述了这些方法的优缺点.探讨了制备过程中的几个主要因素对支撑体的孔径大小及其分布、空隙率、机械强度等重要参数的影响.并指出目前无机陶瓷支撑体的研究过程中存在的主要问题及今后的研究方向.     

Sintering Effects on the Porous Characteristics of Functionally Gradient Ceramic Membrane Structures

A method to drain cast porous ceramics has been conceived and established, where samples were shown to have a functionally gradient cross-section with a continuously increasing mean particle size between the two principal surfaces.Ceramic discs approximately 45 mm in diameter, and 3.3 mm thick were cast by sedimentation. These green bodies were dried prior to sintering. Maximum sintering temperature and the length of the sintering soak time were varied for samples made from suspensions of both 5 and 10 volume percent solids. Mercury porosimetry was used to obtain the porosity and pore size distribution in each sample. Additionally, a number of atomic force microscopy (AFM) measurements were made on some samples in order to correlate bulk porous properties with those on the outside surfaces.The results showed that as the sintering temperature increased, the densification of the bodies proceeded more rapidly. In general, the longer the sintering soak time, the denser the samples became as well. For the samples prepared at the lower temperatures however, the porosity showed less of a soak time dependence. The green body had a clustered and asymmetric microstructure, which contributed to differing degrees of localized densification and coarsening effects depending on the sintering temperature. Densification effects were more pronounced with the samples made from the more concentrated suspenisions.There was an inverse correlation between the bulk and surface pore dimensions, attributable to the different size scales of particles in the two regions. The much finer surface layer particles were able to undergo some amount of densification while surface diffusion sintering mechanisms were primarily at work elsewhere in the structure.