Papers by Author: Kyeong Ho Cheon

Abstract: Zeolite has been used as catalyzer, absorbent, ion-exchange matter and dehydrating agent due to its excellent catalytic property and ion-exchange. In recent years, many studies have been conducted to apply zeolite as new materials such as zeolite membranes and zeolite sensor films. To introduce properties of zeolite, it should be examined how zeolite could be reacted other materials. In this study, it is investigated whether zeolite is successfully synthesized or not when clay and/or sewage sludge coexist with zeolite precursor. Zeolite precursor was made of liquid sodium silicate and sodium aluminate. Mixing ratio of caly and/or sewage sludge is 0-10%(wt.). To compare two processes, the mixture was synthsized by hydrothermal method and high temperature sintering process. It is synthesized by hydrothermal with sintering at high temperature process. The resulting materials were characterized by XRD and SEM. As a result, various type of zeolite such as zeolite X, zeolite A and zeolite P1 was successfully synthesized by hydrothermal method when clay and/or sewage coexist with zeolite precursor. However, zeolite was rarely synthesized by high temperature sintering process. Therefore, when preperation of zeolite material mixed with other material such as clay and sewage sludge, hydrothermal method is more effective than sintering at high temperature process.

Abstract: Zeolite are used as adsorbent, catalyst and ionexchang material. But it limited to extend the usage of the zeolite since almost zeolite synthesized by hydrothermal method. The purpose of this study was to synthesis zeolite by calcination at high temperature due to extend the application of zeolite, as ceramics process. The effect of aging temperature and time, crystallization temperature on the synthesis of zeolite has been studied. Aging was performed at room temperature~70°C during 0~3days. After aging, zeolite precursor sinter for 1 hours at 300, 400, 500°C in furnace. The resulting materials were characterized by XRD, TG, SEM When the aging time is less than 1 day zeolite was not synthesized. But zeolite A obtained from precursor of aging time is more than 1 day at all firing temperature. As a result the aging time and aging temperature is increased, the zeolite synthesis time is decreased. Therefore aging is benefit process on synthesis of zeolite at high temperature.

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: As a basic stage for developing new construction material utilizing sewage sludge ash, this study is identified by specific material characteristics through XRD, SEM, uniaxial compressive strength, porosity, and the drying shrinkage by manufacturing mortar with sewage sludge ash. The average drying shrinkage of sewage sludge ash mortar aged 7 days showed 88% of the strain of the one aged 28 days. The porosity of sewage sludge ash mortar was about 7~10%. The more quick lime and blast furnace slag were added, the less porosity appeared.