Papers by Keyword: Membrane

Abstract: The aim of this paper is an introduction to a very specific area of civil engineering, which is known as tensile structures (structures acting only in tension). These structures are associated with unique aspects of their design. As a result of practically zero bending stiffness, it is not possible to separate the shape and the static analysis of these structures. Shape generation is the aim of the process well known as form-finding. As a consequence of these and many other facts, it is necessary in this case to use a special way of design process, which abounds in many differences in comparison with usual design process.

Abstract: Reverse osmosis membrane is usually used to desalination. With the development of membrane materials and technology, the performance of reverse osmosis membrane is improved continuously, and the interception rate of organic matter is higher, the separation rate of the organic matter is obviously improved. The research progress and application status of separating organics in aqueous solution by reverse osmosis membrane is presented in this paper. The future research direction and application of reverse osmosis membrane for separating organics from aqueous solution were also analyzed and prospected.

Abstract: The relative adsorption coefficient, a novel parameter was introduced to describe the dominant adsorption ability of ions in cation membrane for all vanadium redox flow battery instead of traditional selectivity coefficient. The parameter as a function of membrane property and vanadium ions in membrane was derived from the relative potential differences in membrane between an isothermal adsorption and an ideal equivalent adsorption. The adsorption isotherms of three kinds of commercial membranes were measured for VO²⁺/H⁺ electrolyte system. The results show the reasonable rules that the relative adsorption coefficients increase as the VO²⁺ contents are increased whereas decrease as the H⁺ contents are increased in electrolyte.

Abstract: This study aimed to synthesis and characterized hydroxyapatite/ chitosan biocomposite for Remazol Blue Dyes Removal. Hydroxyapatite was extracted from egg shell and incooporated with commercial chitosan to improve its mechanical strength and adsorption capacity. The prepared adsorbent was characterized in term of morphology using scanning electron microscope and the presence of funtional group in this biocomposite were confirmed by ATR-FTIR. Performance of hydroxyapatite/ chitosan was evaluted by its efficiency for remazol blue dyes removal. The observed results show that the developed adsorbent achieved the highest adsorption capacity for about 95 % dyes removal. The findings in this study perhaps can be used as a fundamental knowledge for the development of dyes wastewater treatment mainly in textile industry.

Abstract: The transient stage is critical due to the stress induced by the chemical and thermal strain. In order to predict this strain, the oxygen activity field through the membrane needs to be known. Usually, the membrane is divided into three zones: the bulk where diffusion takes place and the two surfaces where exchanges between atmosphere and membrane take place. Oxygen bulk diffusion is well described by the Wagner theory. A consensus has not yet emerged regarding the surface exchange models proposed in the literature. Moreover, these models describe the permanent state, and cannot be extended to the transient stage. A new macroscopic surface exchange model which allows computing transient stage is proposed. This model assumed that the oxygen flux is governed by the association/dissociation of adsorbed oxygen and by the high energetic cost of oxygen reduction/oxidation. Then, the balance of transient specie only present on the surface is introduced to account for these two phenomena. The oxygen activity fields predicted by the proposed model are in agreement with the measures of chemical potential drop between the membrane and the atmosphere in permanent state. Transient stage measured during isothermal expansion test is partially reproduced.

Abstract: The aim of this paper is to review the recent developments conducted by our groups for the achievement of 3C-SiC based heterostructures compatible for MEMS applications. It deals with different aspects, from the influence of the defects generated at the 3C-SiC/Si interface on the mechanical properties to the elaboration of new multilayered structures, required for specific applications like, for example, Atomic Force Microscopy.

Abstract: The dome-shaped membrane is very important part of the micro/nano devices. The dome-shaped with the thickness of 150 μm and a radius of 3.2 mm was fabricated using the soft lithography process. The Polydimethylsiloxane (PDMS) was selected as a material because it deformable and suitable to implement as a membrane. Soft lithography is based on pattern transfer using a mold that is patterning the substrate material. In this paper, two techniques were suggested to fabricate the dome-shaped membrane which are reflow technique and stamping technique. The comparison was made for both techniques using a Scanning Electron Microscope (SEM) and it seems the stamping technique has an advantage where the uniform thickness of the dome-shaped membrane can be achieved. The discussion on the temperature effect of a stamping technique shows that the suitable temperature to harden the PDMS is in temperature room where the bubbles can be eliminated under this temperature.

Abstract: In the present work, the rheological properties in terms of shear stress and viscosity of Kaolin/Polyether-Sulfone (PESf) of varying ratio were investigated by a rotating rheometer. The shear rate of Kaolin/PESf sample was measured at increasing interval shear rate. By assuming that the fluid behaves like a typical Non-newtonian polymeric liquid, the consistency index, K and flow index, n were able to be determined. Thus, the rheology behaviors of the kaolin/PESf suspension could be investigated at a wider range of shear rate. The shear stress was found to increase with increasing shear rate, with the rate of change quite apparent at low shear rate. At higher shear rate, the shear stress increases definitively with the increase of kaolin content. On the other hand, the viscosity decreased at a faster rate initially and slows down to monotonous rate as the shear rate increases. Evidently at increasing shear rate, the viscosity tends to become constant as the deviation become smaller which is also known as zero shear rate viscosity region.

Abstract: The present study is aimed at deriving study factors appropriate for removal of heavy metals in a region with combined contamination of non-biodegradable organics or heavy metal ions in soil or underground water contamination or a region with underground water contamination using a composite alternating current electromagnetic field with combined modulation of an electric and a magnetic field. In addition, it is directed at deriving fundamental experiment, design factors that can be utilized in removing organic contaminants or metal-organic complexes having polarity of an electric charge. The continuous-type apparatus for fusion process in a composite alternating current electric field employed in the present study was designed to process a maximum of 260 L. Each configuration is provided with electrolytic decomposition apparatus, Magnetic Equipment, Power supply and Electrode plates with an adjustable distance between electrodes. By measuring oxidation and reduction processes of ions appearing in chemical reaction processes, electric potentials produced by injection of a negative reactivity electrode into an aqueous solution in a reversible redox equilibrium condition were measured.

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.