Materials Science Forum Vols. 544-545

Abstract: In this research, a up-flow filtration device was developed for the on-site treatment of urban stormwater runoff during storm events, and particle removal characteristic of porous polypropylene as a filter material was experimentally examined. The up-flow filtration device showed high removal efficiency, more than 90% (mainly 95-98%) of the SS concentration of influent particles. After the sedimentation in the bottom part of up-flow filtration device, the up-flow filtration filled with porous polypropylene material was able to remove more over 70% of the SS concentration in the up-flow. The increase rate of captured particle amount retained in 10, 20 cm from the bottom of filter bed was lower while flow rate increased. This is attributed to the fact that fine particles detached or not removed by the bottom of filter bed were mainly retained in that section. The particles (mainly finer particles) captures were increased by those particles (mainly large particles) retained in the initial stage for influent particles. However, the improvement of particle removal efficiency (as SS concentration) was not observed along with this phenomenon. The reason may relate to the fact that the particles retained by the captured particles in the initial stage were fine particles.

Abstract: In this study, the capping effects of granular gypsum (Ca2SO4·2H2O) and sand on sediment and water column were evaluated in in-situ experiments in Lake Paldang. The results indicate that capping treatment is very effective for the restoration of eutrophied lake. It was demonstrated that phosphorus, T-N and T-P concentration in the water column of treated basin was relatively lower than control basin. As a consequence of reduction of nutrient concentration by capping treatment, chlorophyll-a concentration in treated basin was considerably lower than control basin. The chlorophyll-a concentration in water column could be reduced to 52% and 25% as compared to control basin, respectively, by the capping treatment with gypsum and sand. From the experimental results, it was concluded that gypsum was more effective capping material than sand for controlling of nutrients and chlorophyll-a. In addition, capping with gypsum bring calcium cation into sediment, which offer more site for phosphorus to bind. In case of the capping with gypsum, apatite P composition, mainly consist of Ca boun P, in the sediment increased from 24% to 43% for the two month of operation.

Abstract: Artificial aggregates made of coal fly ash, which is classified as an industrial byproduct, was tested to oxidize hydrogen sulfide under various testing conditions. For the determination of optimum condition for converting coal fly ash to aggregates, specimens were prepared by varying ratio of fly ash, cement, water, and foaming agent. These specimens were tested to determine specific gravity, water absorption, and compressive strength. Specimens, which were used for the removal of hydrogen sulfide, were selected based on the measured specific gravity, water absorption, and compressive strength. Tests for hydrogen sulfide removal were performed via serial batch kinetic tests. Under the testing conditions used in this study, removal rates of hydrogen sulfide were linearly proportional to amounts of coal fly ash.

Abstract: Recently, solidification processing by cement material of waste that isn’t only increasing but also study is now in progress. Ettringite(Ca6[Al(OH)6]2(SO4)3•26H2O), which is a hydration product of calcium aluminate minerals is highly effective at immobilizing heavy metallic ions through a substitution mechanism. An aqueous solution containing calcium hydroxide, aluminum sulfate, and CrCl3(trivalent chromium) was subjected to irradiate by ultrasonic irradiation under atmospheric pressure to investigate its effect on the synthesis of Cr(III)-ettringite. The verified XRD (100) peak tended to shift to the left and changed morphology as CrCl3 input.

Abstract: Most carbonation processes utilizing municipal solid waste incineration bottom ash characteristically involve a high water content (over 100%). In this work, we developed an improved carbonation process, utilizing various water contents. In addition, we investigated the characteristics of a carbonation reaction using municipal solid waste incinerator bottom ash as a function of water content and their effects on the stabilization of copper and lead. As a result of such a carbonation reaction, the effect on the stabilization of heavy metals can be obtained. Due to this, the leaching concentrations of these were reduced. In a high water content, calcium aluminum compounds via carbonation reaction adsorbed Cu and Pb ions. Where a low water content (especially 30%) is present, particle surfaces are surrounded by calcium aluminum compounds of bottom ash as a result of the carbonation process. The leaching concentration of Cu and Pb were decreased through the carbonation process.

Abstract: Conversion of used glass bottles to porous materials was investigated for recycling of used glasses. The ordinary method to prepare porous materials from glass needs vesicants such as calcium carbonate and silicon carbide that decompose at high temperatures to produce gas, and the gas is trapped in softened glass to form pores. In this study, used glass bottles were converted to porous plates by using hydrothermal technique. First, a glass powder is hydrothermally treated at low temperatures, so that water diffuses into the glass structure. Water is released as vapor to form pores in the softened glass, when the hydrothermally treated glass powder is heated at high temperatures. Thus, this process gives porous materials with a fine structure including closed pores at lower temperature than the ordinary method. The effects of hydrothermal treatment and calcination conditions on bulk density of the resulted porous materials were investigated with a small scale to determine the conditions to get light porous materials. Finally, porous plates (45x45x3 cm3 in size) with density of 0.45g/cm3 were produced by hydrothermal treatment of the glass powder at 180°C in a large autoclave with inside volume of 2.5 m3, followed by calcination at 800°C in a continuous heater with 18 m in length.

Abstract: For low temperature co-fired ceramics (LTCC) materials, BaO-B2O3-MgO-Al2O3 glass system was tested. The starting temperature for densification of a sintered body was at 700°C and the onset temperature for crystallization of a sintered body was 820°C. With the sintering temperature, the sintered body was investigated with shrinkage, crystal phases, thermal properties, and mechanical properties. The glass transition temperature was constant with increasing frit size. However, the onset point of crystallization increased with increasing frit size. The formation of crystal phase was celsian (BaAl2Si2O8). From our results, it is possible to achieve the glass-ceramic having the high strength and the ability of sintering at low temperature using controlling the sintering temperature of BaO-B2O3-MgO-Al2O3 system glass frit.

Abstract: We made artificial soil using sewage sludge, the organic wastes. The optimum composition is 50% of sewage sludge cake, 45% of illite low-quality clay, 3% of glassfrit, and 2% of other components. The surface was coated with γ-alumina. For an optimum manufacturing condition, we sintered and bubbled the plastic material with dry surface by flowing N2 gas at 800°C for 20 minutes. The developed artificial soil shows excellent characteristics; more than 60% of porosity, of 0.8 of density g/cm3, 80ton/m2 of compression, pH 7.4, cation exchange capacity (CEC) 10 meq/100g and about 2000 of hydraulic conductivity. The developed product performs 1.5 ~ 10 times better than the existing perlite in open porosity, nutrient holding capacity, proof compression and CEC. However, the bulk density is 1.5 times higher and heavier than perlite, it is not so problematic to green roof. The developed artificial soil shows positive effect on the development of ecotype leaf or the growth speed by period comparative to the common fertile soil. The number of pollens and lipid shows excellent growth on the artificial soil. The product can be applied to various kinds of plants such as flowering plants, foliage plants, trees and ground cover plant. It can also be applicable to other large amounts of plants grown on the other artificial grounds (slope, road, etc.)

Abstract: Ferroelectric PZT(70/30) thick films were fabricated by the hybrid technique adding the sol coating process to the screen-printing process to obtain a good densification. Structural and electrical properties of the thick films with the sol concentration were investigated. The relative dielectric constant increased and dielectric loss decreased with increasing the sol concentration, the values of the thick film coated with sol concentration of 1.5 M were 698 and 2.5 % at 1 kHz, respectively. And the remanent polarization and dielectric breakdown strength of the thick film coated with sol concentration of 1.5 M were about 38 μC/cm2 and 200 kV/cm, respectively. The leakage current densities were less than 10-8 A/cm2 at the applied electric field range of 0-100 kV/cm in all thick films.

Abstract: Cotton, a lignocellulosic fiber and environment friendly natural material, was tested for its ability to sorb diesel oil from the pure diesel oil bath and the diesel oil containing water bath. The fiber was ground to disrupt the lumen structure or extracted with diethyl ether to remove wax from cotton. Diethyl ether is an organic solvent and extracts only extractives in the cell wall. Oil sorption capacity was the highest in control as 30.6 g/g in the pure diesel oil bath, and the lowest in ground cotton as 0.8 g/g in the diesel oil containing water bath. Cotton is mainly composed of hydrophilic components and sorb water more easily than oil. As a result diesel oil sorption capacity was much higher in the oil bath than in the water bath. However, after grinding and passing through 20 mesh screen (0.86 cm), wax is preserved but the lumen structure of cotton, of which the fiber length is about 18 mm, is disrupted by grinding and can not hold oil. Therefore, the diesel oil sorption capacity of cotton was decreased significantly to 5.2 g/g in the pure diesel oil bath, and to 0.8 g/g in the water bath, compared to those of control. And because wax is removed but lumen structure is not destroyed after diethyl ether extraction, the diesel oil sorption capacity decreased slightly to 27.7 g/g in the oil bath and to 7.5 g/g in the water. When cotton was presoaked in water, cotton sank during the presoaking process, and so the oil sorption capacity could not be determined. Grinding, extractingand presoaking all contributed to the changes in oil sorption capacity. The most significant change is attributed to the reduction in the particle size of cotton.