Papers by Author: Beom Suk Kim

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.

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.

Abstract: This study was conducted to investigate on crystallization condition and its effect on quality of melted slag that was made from incineration ash of domestic waste. By increasing operating temperature, good crystallization was developed and 900~1,000°C was proved optimal. Longer detention time made better crystallization development, and critical detention time was 3 hour. But too a long detention time caused residual stress by mutual interference of long crystals. Cooling rate might affect the quality of crystallization, but below 5°C/min had no difference. For quality and economics, minimum operating conditions could be comparatively low temperature of 800°C and detention time of 1~3 hour from which high Vickers hardness of about 660~720 kgf/mm2 was achieved. It was compared well with crystallized commercial glass which is about 630 kgf/mm2. Thus, optimum crystallization conditions was suggested to be : temperature 900~1000°C, detention time 3 hours, and cooling rate 5°C /min. Also, observation of microstructure of crystallized slag by SEM identified reinforcement of matrix by particles and crack deflection that could render the crystallized slag an improved mechanical strength.

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: The purpose of this study is to develop a new system to control effective discharge of active substances such as agricultural chemicals. To synthesize a naturally dissolvable polymer; ε-caprolactone and diglycolide were copolymerized with ethylene glycol as an initiator to produce macrodiol. As macrodiol has hydroxyl groups in both ends, they are modified with methacryloyl chloride for photochemical networking. After standard macromonomer produced by this procedure was physically mixed with methylene blue, it was networked with ultra-violet rays to be filmed. This film is naturally dissolvable and hydrolytic. As a result of hydrolytic test with a crosslinked structure of 10 % methylene blue, it decreased by 9 % for seven weeks in 37 °C phosphate buffer solution (pH = 7). Thus, we verified that active substance can be discharged from a crosslinked structure for a long time at a constant rate under room temperature.