Papers by Keyword: Pore Size

Abstract: Retracted paper: Crystallization of a salt in a porous medium can lead to the generation of stresses on the pore wall. This stress generation mechanism causes the phenomenon of surface heave, i.e. the upward displacement of the porous material surface.This surface heave phenomenon is studied from experiments with random packings of particles (glass beads) confined in a quasi-2D cell when the crystallization of sodium chloride is induced by evaporation. It is shown that the grain size has a significant impact on the surface heave. In addition, it show the existence of an optimal grain size maximizing the heave. This suggest that the bead size dependence is not related to the mechanical aspect of the problem but is rather linked to the impact of the bead size on the morphology and internal properties of the growing subflorescence.

Abstract: The utilization of the moving bed biofilm reactor (MBBR) has been identified as a promising technology for reducing water pollutants. This study focuses on designing a novel bio-carrier using 3D printing technology for use in an MBBR for wastewater treatment. The bio-carrier is made of polypropylene filament with four variations in specific surface area. The study investigates the relationship between the specific surface area and the amount of adhering biofilm on the bio-carrier. Results show that type-4 bio-carrier with a specific surface area of 1438.16 m²/m³ and a pore diameter of 1.8 mm to 4.9 mm has the highest mass of biofilm attachment at 2.598 grams. This research provides insights for designing bio-carriers with suitable pore diameters and specific surface areas for improved MBBR performance in wastewater treatment.

Abstract: Investigation of the effect of low-pressure NLTP in nitrogen, argon, propane-butane and air on the properties of a multilayer medical-purpose material based on polypropylene used for the manufacture of sanitary-hygienic and medical products. It is shown that after plasma treatment of argon, nitrogen, propane-butane, the surface polarity of the CMC material changes significantly, as evidenced by a decrease in the wettability angle and an increase in capillarity. The most significant changes in indicators are observed in the case of plasma treatment in argon and nitrogen. However, in the case of argon, less processing time is required to achieve the effect. Plasma treatment leads to a slight decrease in tensile strength, no more than 10-15%. It is also shown that when plasma is treated in an argon atmosphere, such characteristics of a nonwoven material as air permeability, hygroscopicity increase, and a decrease in rigidity is observed. The study of the structure of the material (pore size) showed that the treatment with NLTP leads to a significant decrease in the size of large pores and an increase in the size of medium and small pores

Abstract: A ceramic membrane has been produced from a natural zeolite. A series of samples has been sintered at range temperature from room temperaure to 900°C. The influence of the sintering temperature on the specific surface area, pore diameter, and surface roughness has been investigated. It has been found that a decrease for value of the specific surface area and average pore diameter from 300°C to 900°C was attributed to a change of the crystalline structure of tridimite from partially to fully crystallized samples. The fabricated membrane has been used successfully to evaluate the separation performance during the treatment of coconut sap. The membranes have a steady state flux from 0.12 to 0.22 mL/min.cm² at an applied pressure of 1 bar.

Abstract: Sintered porous media are considered to be one of the best candidates to cool high temperature gas turbine components with blades and vanes for next-generation air cooling. The sintered porous media used in this study is made of the stainless steel SUS316L by metal injection molding process. The complex interaction between fluid and the porous medium causes fluid pressure drop when the fluid is forced to flow through the porous surface. In addition, the information on the relation between porosity and pressure drop of the porous media is important to saving the costs of the filter application and cooling process. This research is intended to understand flow characteristics of the porous media with the air fluid movement according to different porosity and pore size for gas turbine application. The experimental data compared with the calculation are examined for different experimental conditions, which indicate flow behavior of erratic and compressible on the microscopic scale porous media.

Abstract: Polymer membranes with fixed pore size or narrow pore size distribution can be used for special separation. However, polymer membranes prepared by conventional method usually have wide pore size distribution and the pore size is hard to control. Here we prepared a porous polymer membrane with uniform pore size via spraying a blend of polystyrene (PS) and polyethylene oxide (PEO) on a filtration paper. Dissolving the water-soluble component (PEO) forms the pore and varying the ratios of PEO in the blend controls the pore size. The pore size and size distribution are also affected by processing parameters, such as the flow rate of solution and carrier gas, and gap length. The morphologies of the membrane are observed using scanning electron microscopy (SEM). The novel polymer membrane with controllable and uniform pore size will be used for the separation of solutes with predictable sizes.

Abstract: UO₂ fuel pellets may be swelling and recrystallization during irradiation. Density, dimension and distribution of pores are main factors to induce irradiation swelling, especially the size distribution of pellet pores plays an important role. 4×4-4 fuel assembly was a high performance fuel assembly which was self-designed and manufactured, the average burn-up of the fuel assembly was 42GWd/tU.For studying the effect of irradiation on pore modality, the specimens of irradiated UO₂ fuel pellets were taken from 4×4-4 fuel assembly after dismantling, microscopic structure and distribution of pores for UO₂ fuel assembly by scanning electron microscopy were studied in this paper. The results showed that there were many cracks in fuel pellets, most micro-cracks were transgranular crack. The release rate of fission gas with burn up were augmentation, which was consistent with the porosity of diversity burp up fuel rod. Pores were distributed non-uniformly in irradiated fuel pellets, gathered at local area and more obvious connectivity of pores. The size of pores after the irradiation was between 0.2~1.2 μm, and mostly distributed at 0.3μm ~0.6 μm; The pores at grain boundary of two adjacent grains was less, the pores at grain boundary were distributed by the way of triangle or quadrilateral. The size of pores was increased than pre-irradiation, but ratio of pores and density of pores were decreased obviously, the phenomenon of irradiation densification was occurred in fuel pellets after irradiated. Recrystallization and Rim structure effect were not found.

Abstract: Effect of pore size on partial discharge in ultra-high voltage ceramic capacitors was investigated. Nondestructive ultrasonic detection was used to measure pore size in ceramics while the partial discharge characteristics were evaluated by a discharge detector. It is found that the partial discharge quantity and discharge inception voltage greatly depend on the size of the biggest pore in the ceramic. The partial discharge characteristics become worse when the inner pore is bigger. Possible explanation is discussed based on an equivalent circuit simulating the capacitor with one large pore.

Abstract: Deoxyribonucleic acid (DNA) adsorption onto particles has applications in biosensors, separation methods, and gene delivery. Mesoporous silica (MPS), which exhibits a high surface area and large pore volume, is used in these applications because its pore size is easily controlled and its surface functional groups are easily exchanged. In this study, three types of MPSs with different pore sizes (2.4, 5.6, and 11.8 nm) were functionalized with different aminosilane coupling reagents and the effects of the MPS pore size and surface functional groups on DNA adsorption were evaluated. As the pore size of MPS increased, MPSs with diethylenetriamine (–3NH₂) adsorbed higher amounts of DNA, whereas MPSs with hexylenediamine groups (–2HNH₂) adsorbed lower amounts of DNA. Moreover, the fitting of DNA adsorption equilibrium data to Langmuir and Freundlich isotherm models was investigated.

Abstract: The porous silicon carbide ceramics were fabricated by adding a variety of low melting point oxides in this paper. The additives were mullite, magnesium oxide, calcium oxide, and vanadium oxide. Effects of the additives content on the properties of porous silicon carbide ceramics were studied. The results showed that, when the additives content was greater than 2.8%, the apparent porosity, the bending strength, the permeability and the pore size were in an inversely proportional relationship with the additives content, while the content was less than 2.8%, proportional relationship was observed. When the additives content reached 2.8%, the porous SiC ceramics showed the best performances.