Eco-Materials Processing and Design IX

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Authors: Shunkichi Ueno, Li Ming Lin, Hideo Nakajima
Abstract: A porous alumina with cylindrical pores was fabricated by unidirectional solidification under hydrogen gas flow (0.1 MPa) using alumina feed rods doped with silica, calcia or sodium oxide. The additives in the feed rods strongly affect the formation of porous structure during the solidification. The porosity increases with increasing silica content. The increase of porosity is enhanced by further addition of sodium oxide. The addition of calcia to the feed rod is effective on the homogenization of pore distribution. The porous alumina with 1mol%CaO and 20mol%SiO2 additives showed 50% porosity and homogeneous pores distribution.
Authors: Woo Keun Lee, Eun Zoo Park, Young Do Kim, Se Gu Son, Ji Hyeon Lee
Abstract: Municipal Solid Waste Incinerator (below MSWI) ash is used to develop inorganic binder for preparing geopolymer concrete in this study. Toxic substituents, such as heavy metals are de-toxificated by above-mentioned new solidity technique. Slag and coal fly ash are used as active filler to enhance compressive strength. MSWI ash was mixed with slag and coal fly ash to make geopolymer concrete. They were solidified under alkali condition and dried at 50°C and 80°C, respectively. Compressive strength was measured to evaluate the characteristics of specimens for the period of 3, 7 and 14 days. Compressive strength measurements show a maximum strength of almost 13.7 MPa after 14 days. The mineral phases of specimen were analyzed by XRD. And the morphology was analyzed by the photo of SEM. The micro-structure of inorganic binder prepared was analyzed by FTIR. Korea Standard leaching Test (KSLT) and TCLP method are used to the environmental safety of inorganic binder. Raw FA measured concentrations of Cu and Pb were 0.30 ppm and 28.31 ppm, respectively. Leaching amounts of heavy metal were noticeably reduced after the solidification of MSWI as with active filler. It is possible to de-toxificate MSWI ash by new solidity techniques. And it may be used as alternative concrete.
Authors: Isaías Juárez-Ramírez, Koji Matsumaru, Kozo Ishizaki, Leticia M. Torres-Martínez
Abstract: Porous ceramic materials with low thermal expansion (LTE) at room temperature were prepared by heating a mixture of SiC or black-Al2O3, vitrified bonding material (VBM) and LiAlSiO4 at temperatures from 850°C to 1100°C. The mixture was prepared in adequate proportions to obtain a material with LTE according to previous works made in our laboratory. It was observed that a change in temperature provoked the formation of a new phase, LiAlSi3O8, which appears above 900°C. The presence of this new phase did not affect the thermal expansion value, keeping LTE at room temperature. All compounds showed around 40% of porosity, and Young’s modulus values of 30 GPa using black-Al2O3 or SiC. X-ray diffraction analysis (XRD) revealed that above 900°C the phase LiAlSi3O8 starts to appear as a consequence of the melting of VBM, which is reacting with the raw materials. SEM micrographs showed the presence of SiC or black-Al2O3 grains joined by VBM, which is acting as a bridge between them.
Authors: Yeong Seok Yoo, Kyeong Ho Cheon, Jae Ik Lee, Beom Suk Kim, Woo Seob Shin, Jong Bo Kim
Abstract: This study is about the development of porous material which shapes Ø3~8mm bead with sewage sludge by molten-salt method. The development of porous material was conducted by 2 different processes. One is made by molding sewage sludge into beads with pelletizer and then coating the beads with molten-salt and lastly sintered at 1050°C, and the other is mixing sewage sludge with molten-salt which is using synthesized zeolite, and then molding the mixture into beads with pelletizer. The molded mixture is finally sintered at 1050°C. We evaluated the value of developed material as sorbent and artificial soil for tree-planning by analyzing surface area, distribution of pore size, and cation exchange capacity(CEC). According to the results, surface coated porous material have 92.8m2/g of surface area and CEC 98.9meq/100g and the mixture sewage sludge with molten-salt have 104.1m2/g of surface area and CEC 140.8meq/100g. Thus, developed porous material can be applied to various uses as sorbent and artificial soil.
Authors: Yeong Seok Yoo, Kyeong Ho Cheon, Jae Ik Lee, Beom Suk Kim, Woo Seob Shin, Gyu Tae Seo
Abstract: This study was conducted to synthesize zeolitic materials using sewage sludge by molten-salt method the effective method was investigate to reduce the thermal treatment time by adding zeolite seed and excessive sodium hydroxide. To synthesis zeolitic materials, sewage sludge was used as Si and Al sources, also Na2SO4 and NaOH were added as stabilizer and mineralizer respectively. Sewage sludge was prepared by calcination at 550°C/3hr to remove organic materials. As a result of thermal treatment at 950°C for 6~24hrs, more than 18 hours was required to synthesize zeolitic materials without adding zeolite seed. On the other hand, it is observed that hydroxyl-sodalite was synthesized in 9 hours thermal treatment and Na-P1 also in 12 hours when zeolite seed was added, but no other differences were observed when excessive sodium hydroxide was added. Consequently, the overall reaction time required could be reduced by adding zeolite seed and changing thermal treatment temperature. However, addition of NaOH does not show significant effect on the reduction of zeolite synthesis time.
Authors: S.Y. Chang, Du Hyung Lee, H.G. Cho, Yo Seung Song, Sung Ho Kim, Chan Bock Lee
Abstract: The Mg-6wt%Al-1wt%Zn alloy powders mixture produced by gas atomization were spark plasma sintered (SPSed). The SPSed sample was coated by plasma electrolytic oxidation (PEO) method, and the microstructure, mechanical and corrosion properties were investigated and compared to the normally sintered sample. The SPSed sample exhibited a microstructure of well-bonded grains with approximately 48 ,m in grain size, which was bigger than that of the normally sintered sample. The coatings on the SPSed sample were characterized by dense and porous layers, while, in the case of the normally sintered sample, the coatings had grown through the grain boundary of substrate with increasing the coating time. The surface roughness, thickness and micro-hardness of coatings on the SPSed sample increased gradually with increasing the coating time. The corrosion property of coatings on the SPSed sample had a tendency to improve with increasing the coating time in 3.5%NaCl solution. However, it was worse than that of coatings on the normally sintered sample.
Authors: Kun Ho Song, Seong Heon Cho, Kwang Rae Lee
Abstract: A membrane permeable to water vapor was prepared and used for dehumidification of air. At a given feed flow rate, the permeation ratios were almost independent to relative humidities of feed stream; The permeation ratios were about 45%, 60%, and 25% at feed flow rate of 50, 70, and 90cc/min, respectively. Permeation ratio might also be enhanced with increasing feed flow rate. However, the permeation ratio (about 25%) at a feed flow rate of 90cc/min was much less than at 50cc/min (about 45%) and 70cc/min (about 60%). This phenomenon might be explained that a water film does form at surface of membrane because the amount of water vapor contained in feed stream of 90cc/min was much more than the permeate through the membrane.
Authors: F. Vázquez Acosta, Leticia M. Torres-Martínez, Lorena L. Garza-Tovar, A. Martínez-de la Cruz, Wallter López González
Abstract: A kaolin obtained from a region near to San Luis Potosí (México) was characterized by X-ray powder diffraction (DRX), optical microscopy (OM), scanning electron microscopy (SEM), X-ray fluorescence (XRF), thermal analysis (DTA/TGA), and chemical analysis. Mineralogical and morphological characteristics of the mineral are presented. The kaolin sample was formed mainly by kaolinite, but other minor phases were also detected such as quartz, cristobalite, trydimite, and dolomite. For iron lixiviation process, concentrate HCl was employed. The high content of volcanic glass detected, evidenced by optical microscopy, revealed an incomplete kaolinization process of the raw material. In agreement with these results, X-ray fluorescence analysis showed high- SiO2 and low-Al2O3 content in the sample as is expected on weakly kaolinized materials.
Authors: S. J. Jeong, K. S. Lee
Abstract: In order to utilize low enthalpy geothermal heat sources, a thermosyphon is a good device which can extract heat without using electric power. The heat transfer in the thermosyphon occurs through the circulation of a working fluid through a sequence of evaporation, vapor transfer, condensation, and liquid return. A two-phase thermosyphon system using carbon dioxide (CO2) as a working fluid has been investigated both experimentally as well as theoretically. Carbon dioxide is the only non-flammable and non-toxic fluid that has the potential to offer environmental safety in a system. A copper tube thermosyphon of total length of 1,000 mm with inside and outside diameters of 9.9 mm and 12.7 mm was developed by consisting of evaporator and condenser sections. The temperature distribution along the thermosyphon was monitored and theninput heat to evaporator section and output heat from condenser were measured as well. The effects of temperature difference between evaporator and condenser section and coolant mass flow rates on the performance of the thermosyphon were determined. The results indicate that the heat flux transferred increased with increasing coolant mass flow rate and temperature difference between evaporation and condenser section. The experimental analysis of the thermosyphon system confirms that the proposed system must be a reliable and highly efficient as well as environmentally friendly alternative to common ground-coupled systems.
Authors: Ju Yeon Won, Sang Wook Lee, Dong Sun Kim, Jung Ki Lee, Seong Jin Hwang, Hyung Sun Kim
Abstract: Photolithographic process is one of the eco-friendly processes for forming the pattern of the barrier ribs in PDP. Controlling the refractive index of glass is important to develop a photosensitive paste for photolithographic process. We studied the refractive index and the structural transition of these glasses by measuring the refractive index, reflectance, density and dielectric constant with changing the SiO2/B2O3 ratio in the SiO2-B2O3-Al2O3 glass system. The refractive index was investigated to the relationship between the thermal and optical properties depending on the composition. It suggests that the thermal and optical properties in borosilicate glasses should be correlated to the glass structure with the SiO2/B2O3 ratio.

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