氧化铝微滤膜孔径的影响因素及控制

首次发现膜泡压孔径随膜厚增加而减小;随烧结温度升高,膜孔道实际几何孔径基本上不变,泡压孔径增大;膜孔径的控制方法为：根据孔径要求选择适当的微粉,通过控制膜厚准确控制膜孔径。     

炭分子筛的孔径分布研究

采用容积法测定了CO2在两种炭分子筛（CMS-200A、CMS-200B）上的吸附等温线,温度为273K、相对压力为0.000001～0.9。通过HK模型和D-R方程对吸附平衡数据进行分析,计算得到了两种炭分子筛的孔径分布。结果表明：两者的孔径分布主要在0.35～0.8nm之间,CMS-200B的平均孔径略大于CMS-200A。HK模型和D-R方程两种方法均可以反映出两种炭分子筛孔径分布的差异,且计算得到的结论是一致的。     

Effect of Attapulgite Pore Size Distribution on Soybean Oil Bleaching

The pore size distribution and specific surface area of the attapulgite was a crucial parameter for the uptake of pigments of oil. Bleaching of the soybean oil with three attapulgites with different pore size distribution, which were assigned a, b, and c, respectively was investigated. The specific surface area and the pore size distribution of the attapulgites were characterized. The Freundlich isotherm analysis was used to evaluate the sorption capacity of the three attapulgite. Sample b gave the highest surface area and sample c the lowest. Sample b exhibited a wider pore distribution (8–65 Å) whereas samples a and c had more micropores smaller than 15 Å. Sample a, in contrast to samples b and c, was characterized by some larger pores (100–170 Å). The sorption capacity followed the sequence: attapulgite sample c > attapulgite sample a > attapulgite sample b. The sorption capacity was decided by the pore size distribution. The more pores with a distribution range 8–32 Å (i.e., close to the diameter of the pigments), the more pigments removed. The attapulgite sample c, which had most pores (8–32 Å) was the best.     

Pore Size Distributions of Polysulfonic UF Membranes and Protein Adsorption

Abstract

To compare actual and effective porous structure in operative conditions of ultrafiltration membranes, flux, retention, and the amount of adsorbed protein have been measured for 0.1% w/w aqueous solutions of several proteins [lysozyme, pepsin, bovine serum albumin (BSA), lipase, and γ-globulin] with molecular weights from 14.6 to 150 kD tangentially filtered through two asymmetric polysulfone membranes, E-100 and E-500. From retention and flux experiments, the dependency of mass transfer coefficients on molecular volume has been analyzed. Results imply that protein molecules behave as being slightly uncoiled, especially when filtered through the smallest pore size membrane. By using a simple sieving model, retention data allow pore size distributions to be obtained. The data are modified by taking into account adsorption and volume hindrance effects in operational conditions.     

玻璃基TiO_2膜的孔径尺寸对其光催化性能的影响

通过在溶胶—凝胶溶液中加入聚乙烯乙二醇有机聚合物 ,利用平板玻璃作衬底 ,制备了多孔 Ti O2 薄膜。扫描电镜观察表明 ,一定的热处理条件下 ,有机聚合物可以显著地改变 Ti O2 薄膜的孔径尺寸。光催化结果显示 :当 Ti O2 膜的孔径尺寸在 15 0～ 2 5 0 nm时 ,它的光催化性能较好。     

Isothermal Drying of Pore Networks: Influence of Friction for Different Pore Structures

An existing network model for isothermal drying of capillary porous media is extended to account for viscosity in the liquid phase so that it is no longer restricted to structures with large pores. Modeling challenges and solution methods are presented in detail. The model is compared with a bundle of capillaries model of drying. Finally, simulation results for two-dimensional pore networks with mono-modal and bimodal pore structure are shown and discussed.     

Isothermal Drying of Pore Networks: Influence of Friction for Different Pore Structures

An existing network model for isothermal drying of capillary porous media is extended to account for viscosity in the liquid phase so that it is no longer restricted to structures with large pores. Modeling challenges and solution methods are presented in detail. The model is compared with a bundle of capillaries model of drying. Finally, simulation results for two-dimensional pore networks with mono-modal and bimodal pore structure are shown and discussed.     

Effect of Calcination Conditions on Crystalline Structure and Pore Size Distribution for a Mesoporous Alumina

In this article, a mesoporous commercial alumina was calcined in the temperature range of 600°C–1200°C. The effect of several parameters such as calcination temperature, calcination time, heating rate, and calcination steps on phase transformation and crystal size was experimentally investigated. The characterization of the commercial mesoporous alumina and samples calcined at 1000°C, 1040°C, 1070°C, 1100°C, and 1200°C by single-step and multi-step calcination was performed using XRD and N₂ adsorption/desorption techniques. For the commercial mesoporous alumina, TG/DTA analysis was also performed. Experimental results showed that mostly pure α-Al₂O₃ was obtained at 1100°C.     

Application of Pore Size Analyzers in Study of Chinese Angelica Slices Drying

The objective of this article is to study the influence of pore size and distribution in plant tissue on drying behavior of plant materials using Chinese Angelica slices as an example. By using an automatic mercury injection apparatus and automatic surface area–porosity analyzer, the study compares the pore size distribution inside the matrix of a sample dried by 200 W microwave and 60°C hot air. The study also characterizes the matrix microstructure by scanning electronic microscopy (SEM) and discusses the drying dynamics of the sample, as well as the rehydration property of the dried sample. This work may be helpful for further investigation of the optimization of drying technology focused on micromechanisms and the quality of dried products.     

Statistical modeling of the geometrical structure of the system of artificial air pores in autoclaved aerated concrete

The geometrical structure of the system of artificial air pores in autoclaved concrete is studied, based on samples from laboratory and industry. The single pores are approximated by spheres, the corresponding radius distribution is determined by means of stereological methods. The resulting distribution is not a classical standard distribution, but instead requires a mixture of three components, one of them Gaussian. The pore system as a whole is approximated by the penetrable-concentric-shell or “cherry-pit” model, which consists of spheres that are partially penetrable. The corresponding hard cores form a random packing of hard spheres. The goodness-of-fit of the model is tested by means of information available from planar sections: the section profile radius distribution and the pair correlation function of profile centers.     

大孔容孔径氧化铝的合成研究

采用中和成胶法,以偏铝酸钠、硫酸铝等为原料,考察了成胶温度、成胶p H值、助剂等条件对合成氧化铝产品性能的影响。结果表明:升高成胶温度,氧化铝产品的结晶度随之增高,比表面积呈先增大后减小的趋势,孔容、孔径增大,在成胶温度为70℃时产品的最可几孔径最大。随成胶pH的升高,氧化铝产品的比表面积逐渐减小,pH=7时以小孔为主,pH=8时孔容增至最大,孔分布向大孔方向偏移,继续增高p H值孔容和大孔比例均减小。在成胶体系中引入2%的P、F、Si作为助剂均可有效提高氧化铝的孔径,助剂F和Si会使氧化铝的比表面积和孔容有所减少,而P会显著提高氧化铝的比表面积和孔容。加入0.2%~1%的B_2O_3作为助剂后,产品的孔径分布向大孔方向显著偏移。     

几种椰壳活性炭材料的孔结构分析

为了筛选在异丙苯法生产苯酚工艺中吸附分离α-甲基苯乙烯的吸附剂，测定了4种椰壳活性炭材料的氮吸附等温线，并用BET模型、t图法、BJH理论等方法对孔结构进行分析与表征。结果表明：2号活性炭为微孔型，具有大量2．3nm以下的孔隙。1号、3号、4号活性炭除了微孔外还含有一定量的中孔。4号活性炭中孔率超过50％，拥有最小的平均中孔孔径，对α-甲基苯乙烯有较强的吸附能力，较适合作为异丙苯法生产苯酚工艺中α-甲基苯乙烯的吸附剂。     

新疆塔中地区地层孔隙压力预测

文章以灰色理论为基础,提出了钻头下部未钻开地层的孔隙压力预测新方法,建立了地层孔隙压力随钻预测灰色模型。该模型是根据上部以钻井段的测井结果,对钻头下部未钻开地层的孔隙压力进行随钻预测。将该项技术应用在新疆塔中地区,计算结果表明,该技术能够大大提高地层孔隙压力的预测精度,准确预报井下异常高压和复杂事故的发生,为现场钻井施工提供了可靠的技术依据。     

颗粒粒径和膜孔径对陶瓷膜微滤微米级颗粒悬浮液的影响

通过测定颗粒悬浮液通过陶瓷微滤膜时的参透通量及污染阻力,确定了陶瓷膜处理微米级颗粒悬浮液时,颗粒粒径和膜孔径对微滤过程的影响和膜污染机理,获得了微米级颗粒悬浮液微滤过程中膜孔径的选择方法。     

干污泥表面形貌及孔隙分布规律

污泥干燥焚烧以回收其热能的资源化利用正受到越来越多的关注。污泥干燥过程中,孔隙的大小及其分布直接影响污泥中液体及气体的传递过程．进而影响干燥速率。为研究干污泥表面形貌及孔隙分布规律,采用扫描电子显微镜观测了干污泥表面形貌。利用动态氮吸附法测量了干污泥的孔隙大小。利用数理统计方法研究了孔隙分布规律,研究结果表明干污泥的孔隙分布服从对数正态分布。建立了孔隙分布模型,求解了5种干污泥的孔隙分布特征参数,模型计算值与实际测量值吻合较好,均方根误差小于18．2％,所建立的干污泥孔隙分布模型具有一定的通用性及准确性。     

多孔陶瓷孔径及其分布测定方法研究进展

孔径及其分布决定了多孔陶瓷的性能及应用,因此对其测定和定量表征非常重要。本文综述了多孔陶瓷孔径及孔径分布的常见测定方法,包括气泡法、压汞法、气体透过法、气体吸附法、气体渗透法、液-液法、悬浮液过滤法、X射线小角度散射法、核磁共振成像法、X射线断层扫描法以及电子显微镜图像分析法。比较了各种测试方法的优缺点,认为电子显微镜图像分析法是最直接有效的测定方法,并对多孔陶瓷的测试表征方法提出了展望。