氧化铝蜂窝陶瓷超滤膜的制备及表征

为了提高陶瓷膜的装填密度,简化制备工艺,选择装填密度高且成本低的蜂窝陶瓷为基体,纳米氧化铝分散液为涂膜液,用悬浮粒子浸涂法进行陶瓷超滤膜的制备,对无负载氧化铝膜进行TG-DSC分析显示复合膜的适宜烧结温度为500℃。通过扫描电镜观察复合膜的表面和截面形貌,膜表面基本完整,可以有效去除悬浮液中粒径大于30 nm的粒子。操作压力为0.1 MPa时,膜的纯水通量为200 L/(m~2·h),膜面积/体积比达到1 670.3,是19通道陶瓷膜的4倍多,降低了单位膜面积占用的体积。     

γ-Al2O3中孔陶瓷膜的制备及表征

以粒径为0.3～0.4 μm的α-Al₂O₃为原料,通过悬浮液真空抽吸法,制备出平均孔径约为70 nm的完整无缺陷的片状α-Al₂O₃支撑体;以仲丁醇铝为前驱体,采用颗粒溶胶路线制备出稳定的Boehmite溶胶,以此溶胶采用浸浆法,在制备的α-Al₂O₃支撑体上制备出完整无缺陷的γ-Al₂O₃中孔膜,并考察了烧成温度对γ-Al₂O₃中孔膜性能的影响。结果表明,本文制备出的γ-Al₂ O₃膜的孔径约为3 nm,对PEG的截留分子量为2800～5300,纯水渗透通量为11.5～25.9 L.m^-2.h^-1［7.6×10⁵ Pa,（14±1）℃］。说明在孔径为70 nm左右的载体上直接制备孔径为3 nm的完整的中孔膜是可行的。     

Preparation and characterization of mesoporous γ-Al2O3 membranes

以粒径为0.3～0.4 μm的α-Al₂O₃为原料,通过悬浮液真空抽吸法,制备出平均孔径约为70 nm的完整无缺陷的片状α-Al₂O₃支撑体;以仲丁醇铝为前驱体,采用颗粒溶胶路线制备出稳定的Boehmite溶胶,以此溶胶采用浸浆法,在制备的α-Al₂O₃支撑体上制备出完整无缺陷的γ-Al₂O₃中孔膜,并考察了烧成温度对γ-Al₂O₃中孔膜性能的影响。结果表明,本文制备出的γ-Al₂ O₃膜的孔径约为3 nm,对PEG的截留分子量为2800～5300,纯水渗透通量为11.5～25.9 L.m^-2.h^-1［7.6×10⁵ Pa,（14±1）℃］。说明在孔径为70 nm左右的载体上直接制备孔径为3 nm的完整的中孔膜是可行的。     

陶瓷膜构型对错流微滤酵母悬浮液性能的影响

采用3种构型的陶瓷微滤膜元件对酵母悬浮液进行错流过滤实验,考察陶瓷膜元件的构型对于其错流过滤性能的影响。结果表明:减小陶瓷膜元件的通道直径可以提高料液在膜表面的剪切力,有助于提高过滤稳定通量和临界压力,在3 m/s膜面流速、0.1 MPa跨膜压差条件下,单管、19通道、55通道的稳定通量分别为96、128、196 L/(m2.h);在3 m/s膜面流速条件下,3种陶瓷膜元件的临界压力分别约为0.15、0.2、0.2 MPa。另外,减小通道直径还可以减小滤饼层的比阻,有利于降低过滤阻力;与提高膜面流速来增大过滤通量的方法相比,减小陶瓷膜的通道直径具有能耗较小的优点。     

新型中空纤维陶瓷膜的制备方法

新型中空纤维陶瓷膜由于具有装填密度大、单位体积膜有效分离面积大、膜壁薄、渗透通量高和节省原料等独特优点而受到广泛关注,在用于多孔和致密陶瓷分离膜、固体氧化物燃料电池、微通道反应器、催化剂载体等方面都有着潜在的应用前景。在概括中空纤维陶瓷膜特点的基础上,综述了中空纤维陶瓷膜的制备方法研究进展,着重分析比较了不同制备方法的优缺点。将相转化法应用于中空纤维陶瓷膜的制备,可实现通过一步成型制造具有自支撑非对称结构的复合陶瓷膜,有利于提高膜的渗透通量、简化膜制备工艺和显著降低制造成本。     

新型中空纤维陶瓷膜的制备方法

新型中空纤维陶瓷膜由于具有装填密度大、单位体积膜有效分离面积大、膜壁薄、渗透通量高和节省原料、易于实现分离设备小型化等独特优点而受到广泛关注,在用于多孔和致密陶瓷分离膜、固体氧化物燃料电池、微通道反应器、催化剂载体等方面都有着潜在的应用前景。本文在概括中空纤维陶瓷膜特点的基础上,综述了中空纤维陶瓷膜的制备方法及研究进展,着重分析比较了不同制备方法的优缺点。将相转化法应用于中空纤维陶瓷膜的制备,可实现通过一步成型制造具有自支撑非对称结构的复合陶瓷膜,有利于提高膜的渗透通量,简化膜制备工艺和显著降低制造成本。     

陶瓷膜处理地表水的工艺

采用混凝沉降与陶瓷膜超滤的组合工艺处理地表水,考察操作模式、膜孔径、膜构型以及膜通量等对膜过滤性能的影响。结果表明:在恒压操作下,终端过滤的操作压差应小于0.075 MPa,对于孔径大于50 nm的陶瓷膜而言,膜通量随孔径变化不大;错流过滤的膜通量随孔径增大而增大;错流过滤的渗透通量是终端过滤的1.5～2.2倍。恒通量操作下,蜂窝陶瓷膜过滤性能优于19通道陶瓷膜,并在恒通量150 L/(m2.h)下稳定运行。混凝沉降-陶瓷膜组合工艺对浊度的去除率大于99%,对吸收254 nm波长紫外线有机物(UV254)的去除率大于47.7%,产品水的部分指标优于GB 5749—2006中的指标。     

陶瓷膜分离钛硅分子筛的实验与模型计算

在面向过程的陶瓷膜材料设计理论模型的基础上,以TS-1钛硅分子筛悬浮液固液分离为应用体系,计算了陶瓷膜分离过程的操作条件与渗透性能的关系,与实验结果有良好的一致性.计算表明,对于平均粒径为290 nm的钛硅分子筛体系,陶瓷膜存在最优孔径区间(200~300 nm),使膜保持高渗透通量.孔径小于200 nm时膜通量随孔径增大而增大,孔径大于300 nm时膜通量随孔径增大而减小;采用孔径为200 nm的陶瓷膜过滤钛硅分子筛,渗透通量随时间的变化关系与模型预测结果一致,稳定通量达到800 L/(m2.h).     

浸浆制备过程中陶瓷膜厚度控制及其模型化

在毛细过滤和薄膜形成机理的基础上,采用化学工程实验与模型化方法,对浸浆成型法制备多孔α-Al₂O₃陶瓷膜过程中,膜厚与影响因素之间的关系进行了理论分析和实验研究. 结果表明：膜厚受到制膜液粉体浓度、制膜液黏度、粉体粒径大小、载体纯水渗透性能以及涂膜过程中浸浆时间和载体提升速度等因素的影响. 通过膜厚与影响因素间的数学模拟,建立了膜厚控制模型. 并以ZrO₂粉体为原料,采用相同方法制备ZrO₂陶瓷膜对模型进行了验证,模拟计算值与实测值基本一致.     

聚丙烯中空纤维膜气体除尘性能

以气体除尘为研究背景,采用平均孔径为0.22 μm的聚丙烯（PP）中空纤维膜为过滤介质,考察了粉尘浓度、过滤气体流速、膜组件装填率、膜壁厚对膜组件除尘性能的影响。结果表明,气体通量随粉尘浓度变化较小,除尘率随粉尘浓度增大而提高、随过滤气体流速增加而减小;气体通量和除尘率均随膜壁厚增大有所增加,并随装填率增加而减小。PP中空纤维膜用于气体除尘其除尘率高达99.9%以上,其中对0.3 μm以上粉尘的截留率均可达到100%,对0.3 μm以下粉尘的除尘率可达99%。     

一体式陶瓷外膜直接乳化法制备单分散水包油乳液

膜乳化法是靠膜两侧的压差使分散相通过微孔膜,以小液滴的形式分散在连续相中而形成乳状液的方法．与转一定体系、高压均化等传统制乳方法相比,膜乳化法所制得的乳液具有液滴尺寸均一、节能、剪应力小等特点,可应用于食品、医药、聚合物工业等领域．过去的十几年中,尽管在膜乳化方面进行了大量的工作,过程参数对乳滴尺寸的影响并未完全研究清楚．甚至在一些研究中,仅仅把平均乳滴直径作为分布参数．     

Effect of surface roughness and mass transfer enhancement on the performance characteristics of nickel-hypophosphite electroless plating baths for metal–ceramic composite membrane fabrication

Mass transfer enhanced electroless plating is a relatively new concept in the field of metal–ceramic composite membrane fabrication. In this article, we present the effect of substrate surface roughness along with various mass transfer enhancement techniques such as solution stirring, membrane stirring and sonication on metal conversion, plating efficiency, thickness, and percent pore densification using electroless plating of nickel on a porous disk shaped ceramic support with a nominal pore size of 700 nm. The plating characteristics were investigated for three different roughness values, stirrer speeds (0–300 rpm) and a loading ratio (defined as membrane area per unit volume of plating solution) value of 196 cm²/L. It was evaluated that stirring as well as sonication had a profound effect on sodium hypophosphite based electroless nickel baths. This led to a reduction in average membrane pore size by 100 nm for stirring and 130 nm for sonication when compared to the base case. Surface roughness was observed to influence the metal deposition characteristics for base case without mass transfer enhancement. Sonication, irrespective of surface roughness, provided the maximum values of selective conversion, densification and membrane thickness along with acceptable values of plating efficiency.     

Stability of latex crossflow filtration: cake properties and critical conditions of deposition

The critical permeation flux is the flux at which cake deposition starts to be detectable. The variations of the critical flux (determined simultaneously by a mass balance and successive variations of transmembrane pressures) during sub-micron latex particles filtration were studied under various operating conditions (membrane pore diameter, shear stress at the membrane surface, latex concentration, surfactant content). These variations were explained taking into account the properties of the suspension and of the fouling deposit (reversibility, specific resistance, thickness, porosity) formed beyond the critical threshold. It was shown that the critical parameter, J_crit/τ_w, which defines the conditions required for stable filtration performance was more appropriate than ΔP_crit/τ_w previously suggested in the literature since J_crit was actually independent of the clean hydraulic resistance of the membrane, and consequently of the membrane pore size. This indicates that there is no need to work with the largest pore size membrane: larger pores will not induce higher critical flux and will not improve the area of the stability zone of the filtration. This work also points out the major impact of surfactants on fouling phenomena and J_crit, observations rarely reported in the literature: the higher the surfactant content, the higher the deposited mass and the lower J_crit.     

19通道多孔陶瓷膜渗透过程的CFD模拟

根据Darcy定律,建立了多孔陶瓷膜中渗透流动的CFD计算模型,定量描述了纯水在多孔陶瓷膜中的渗流情况。根据CFD模型,采用有限体积法,模拟计算出四种平均孔径陶瓷膜的纯水通量,并与实验值进行了对比,结果吻合较好。采用该模型,定量计算出19通道陶瓷膜中每个通道对整体陶瓷膜渗透通量的贡献,并分析了其中的变化规律,为多孔陶瓷膜的构型优化奠定了基础。     

陶瓷膜澄清厚朴水提液膜污染机理的研究

采用一个经典模型描述了厚朴水提液过滤过程中的通量衰减,通过模型参数分析了膜的污染机理。分析结果表明孔径为50,200,500 nm的陶瓷膜主要由"完全孔堵塞"机理、"滤饼过滤"机理和"部分孔堵塞"机理控制;通过此污染机理的分析来指导膜清洗,孔径为50,200,500 nm的陶瓷膜清洗后分别恢复了84.5%,89.4%和90.0%左右;实验表明孔径为200 nm的陶瓷膜较适合厚朴水提液体系。     

混凝耦合多孔陶瓷膜净化河水简

Membrane filtration technology combined with coagulation is widely used to purify river water. In this study, micro filtration （MF） and ultrafiltration （UF） ceramic membranes were combined with coagulation to treat local river water located at Xinghua, Jiangsu province, China. The operation parameters, fouling mechanism and pilot-scale tests were investigated. The results show that the pore size of membrane has small effect on the pseudo-steady flux for dead-end filtration, and the increase of flux in MF process is more than that in UF process for cross-flow filtration with the same increase of cross-flow velocity. The membrane pore size has little influence on the water quality. The analysis on membrane fouling mechanism shows that the cake filtrationhas significant in fluence on the pseudo-steady flux and water quality for the membrane with pore size of 50, 200 and 500 nm. For the membrane with pore size of 200 nm and backwashing employed in our pilot study, a constant flux of 150 L-m^-2-h^-1 was reached during stable operation, with the removal efficiency of turbidity, total organic carbon （TOC） and UV254 higher than 99%, 45% and 48%, respectively. The study demonstrates that coagulation-porous ceramic membrane hybrid process is a reliable method for river water purification.     

Modeling of the Relationship Between Pore Size Distribution and Thickness of Ceramic MF Membrane

The pore size distribution(PSD)measured by the gas bubble point(GBP)method ofceramic microfiltration(MF)membranes prepared by suspension technique was found to be signifi-cantly influenced by the membrane thickness.A culm-like model for pore structure was introduced tocharacterize the membrane pores instead of the conventional model which does not reflect the radiusvariation along the pore passages and is unable to explain the thickness effect on the membrane PSD.A laminate structure,taking the culm-like model for pore structure into consideration,was hypoth-esized for ceramic MF membranes.A mathematical model was then established to quantitativelydescribe the relationship between the membrane number PSD and the membrane thickness.Goodresults were obtained for the correlation of mean pore size and simulation of the PSD for ceramicMF membranes.     

Elaboration and characterisation of low cost ceramic support membrane

Abstract

A porous tubular ceramic membrane was prepared from low cost Tunisian clay. The characterisation of the raw material and the effect of the sintering temperature on the morphology, pores size distribution and the mechanical properties of the ceramic membrane were studied. A ceramic membrane fired at 1000°C for 1?h presented a mean pore diameter of ～1·04?μm. The porosity was equal to 38?vol.-%. The filtration of a 0·5?g?L^?1 bovine serum albumin solution indicated that the limiting flux of permeate was 245?L?h^?1?m^?2?bar^?1, which corresponded to a retention rate of about 13%.     

硅橡胶/陶瓷复合膜反应器中CO2合成甲醇(Ⅱ)过程行为分析

以在膜反应器中进行的CO₂ 加氢合成甲醇的复杂反应 (平行反应 )体系为模型反应建立了等温一维拟均相膜反应器并流模型 ,运用Runge -Kutta法对膜反应器中的反应过程行为进行模拟 ,并讨论了Da、α、Φ、p_r、q₁、T、γ和L₁等参数对反应过程行为的影响