Papers by Keyword: Membrane

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Authors: N.F. Morozov, P.E. Tovstik
Abstract: Buckling modes of a linearly elastic compressed medium are discussed. Stability of a plate lying on a soft elastic foundation is investigated. To the plate surface a membrane with initial stresses is attached. The stresses in the membrane simulate difference of equilibrium distances between atoms of crystal lattices of a surface layer (membrane) and of a plate. Also the influence of force and thermal stresses is studied. The chessboard-like stable buckling mode appears on the membrane surface at the stability loss. The ways of control of the wave length of buckling mode are discussed.
Authors: Milos Huttner, Jiří Maca, Petr Fajman
Abstract: This paper presents a practical application of form-finding process of cable-membrane structures. The dynamic relaxation method with kinetic damping is used as the computation method for numerical analysis. A brief description of the construction, a description of the models and the way of solving tasks will be introduced. The correct operation of the implemented algorithm will be compared with a commercial program.
Authors: Chu Wan Hong, Frank A. Müller, Peter Greil
Authors: Mirele Costa da Silva, Francisco Nilson da Silva, Hélio de Lucena Lira, Normanda Lino de Freitas
Abstract: Given the diversity of areas in which applications of ceramic membranes are included, the literature has shown great interest of researchers to obtain these materials with powders synthesized by different chemical methods. Thus, this work aims at the synthesis of alumina by Pechini method, the 2:1 ratio of citric acid: metal cations, calcined to 1100°C, to obtain membranes. The synthesized powders were characterized by thermal analysis, XRD and particle size distribution, since the membranes were characterized by SEM and mercury porosimetry. The results for the obtained powders showed total mass loss of 61.60%, an alpha-alumina phase with crystallite size of 45.2 nm. As for the membranes, these showed heterogeneously distributed particles with different sizes and irregular geometry, reaching average pore diameter of 0.6 μm me 47% porosity, and thus are characterized for application in microfiltration processes.
Authors: Mettaya Kitiwan, Duangduen Atong
Abstract: The palladium membrane has been developed for high temperature separation of hydrogen from other syngas molecules. In this study, tubular α-alumina substrate was used as a support for increase mechanical strength for thin palladium membrane. Prior depositing of palladium film, a dip-coating of palladium nuclei was performed to cover the substrate. Afterward, surface of activated support was modified with a thin intermediate layer for improving adhesion between support and Pd membrane. Electroless plating of dense palladium membrane was achieved from the plating bath containing EDTA stabilized palladium complex and hydrazine. The microstructural characteristics of palladium membranes were analyzed.
Authors: Sofiah Hamzah, Nora'aini Ali, Marinah Mohd Ariffin, Abdul Wahab Mohammad
Abstract: This study aimed to characterize a highly specific affinity membrane for trypsin separation. The basic membrane was fabricated using 15% polysulfone via phase inversion technique. Membrane surface modification was employed by immersing the native membrane into the chitosan solution for 60 minutes dip times. Further modification was performed to activate the PSf/chitosan hybrid membrane using glutaraldehyde before ligand immobilization. The prepared affinity membrane was characterized in term of morphology using scanning electron microscope and the presence of aldehyde group and ovomucoid were confirmed by ATR-FTIR. Performance of affinity membrane was valuted by adsorption study of trypsin enzyme. The observed results show that the developed affinity membrane, with 0.7 mg/ml ligands was able to adsorb trypsin for about 0.219 mg/cm2 membrane
Authors: F. Widhi Mahatmanti, Nuryono, Narsito
Abstract: In this research, polyethylene glycol (PEG) and rice hull ash silica were blended to modify chitosan membrane to improve the adsorption capability of copper ion. Scanning electron microscopy (SEM) and water affinity were performed to characterize membranes. Batch adsorption experiments were conducted with various contact time and Cu (II) concentrations to evaluate the adsorption kinetics and thermodynamics. Results show that adsorption fitted to Langmuir model and followed a kinetic model of pseudo-second-order.
Authors: Ik Jin Kim, Hae Jin Lee
Abstract: NaX molecular sieve films on ceramic paper prepared by in-situ hydrothermal method were investigated. The NaX zeolite seed crystals of a uniform size of 5 µm were synthesized by hydrothermal method in a mother solution having a composition of 3.5Na2O : Al2O3 : 2.1SiO2 : 500 ~ 1000 H2O. These dip-coated NaX seed crystals on ceramic paper lead to further the thickness (20 ~ 100 µm) of NaX film on the substrate at 90°C for longer 3~7 days in autoclave. Pure zeolite films consisting of a continuous intergrown of 5~ 20 µm NaX crystal have been prepared on the substrates. The zeolite films were characterized by XRD, SEM, BET and XRF.
Authors: R.E. Levänen
Abstract: Consolidation of colloidal particles onto porous ceramic substrate is the critical issue in the ceramic membrane preparation. The membrane functional properties are determined mainly by the powder properties, but also by the colloidal condition of the slip. This presentation concentrates on the colloidal processing of submicron alumina for the membrane preparation and for the membrane layer formation based on the capillary colloidal filtration. The solid content of the slip and the degree of deflocculation are the primary factors for the control of the membrane layer growth and pore properties. Electrostatic and electrosteric dispersion lead into different degree of deflocculation and different surface charge, which further resulted on differences in membrane layer growth behavior. Additives, such as polyelectrolytes, electrolytes, binders have also effect on the colloidal condition of the slip, but also have effect on the properties of the liquid phase of the slip. Changes in viscosity and surface tension of liquid phase have also significant effect on the membrane layer growth behavior.
Authors: Sang An Ha, Dong Kyun Kim, Woo Jin Lee, Chang Yong Kang, Kwon Hoo Kim, Jei Pil Wang
Abstract: Comparison study of oxidation behavior of low carbon steel was conducted at the temperature range of 500°C to 700°C under a 0.2 atm oxygen pressure by continuous and discontinuous oxidation methods. Oxidation rate of both cases was found to be increased with increasing temperature from 500°C to 700°C and obeyed parabolic rate law. In addition, activation energy for the continuous oxidation of steel was found to be a 164.8 kJ/mole, which means that oxidation rate is proportionally dependant on temperature. In case of cyclic oxidation, the oxidation rate was shown to faster than continuous oxidation at all temperatures due to direction oxidation through spallation of the oxide layer.
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