Papers by Author: Young Do Kim

Abstract: Titanium dioxides were synthesized from two different titanium salts, which contained chlorine and sulfur respectively. Titanium dioxide prepared from TiCi₄ and had a particle size of ca. 20nm and its phase transition from anatase to rutile stated at 500°C. Titanium dioxide from TiOSO₄ had a particle size of ca. 50nm and retained its anatase and sperit structure until 700°C by calcination. For the photocatalytic evaluation of these titanium dioxides, photocatlytic oxidation of organic model pollutant, humic acid, have been conducted. UV absorbance decrease by titanium dioxides prepared from both from TiCi₄ and TiOSO₄ at room temperature showed very similar results, compared to titanium dioxide prepared from TiCi₄ at higher temperature.

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.

Abstract: The goal of the present work was investigated development of ET(Environmental Technology) industrial geopolymer materials from mixture Silica Mine Waste(SW) and ground granulated blast furnace slag(GGBFS) and alkali activator solution(sodium silicate) by the Geopolymer Technique at ambient temperature. As for the synthesis of geopolymeric monoliths, four different GGBFS content(10wt%, 20wt%, 30wt%, 40wt%) and three types of GGBFS(GGBFS-1(blaine 4,000cm2/g), GGBFS-2(6,000cm2/g), GGBFS-3(8,000cm2/g)) are investigated to obtain the optimum synthesis condition based on the high compressive strength. The weight ratio between the alkali activator solution and dry mix(SW and GGBFS) were 0.25 and 0.3, respectively. The results showed that geopolymeric monolith containing 30wt% GGBFS exhibits higher compressive strength and increased along with increase of GGBFS blaine. The compressive strengths of GGBFS-1, GGBFS-2 and GGBFS-3 are 66.7MPa, 83.1MPa, 94.1MPa, respectively. Additionally, scanning electron microscope (SEM) techniques are used to characterize the microstructure of the geopolymeric monoliths. SEM observation shows that it is possible to have amorphous aluminosilicate gel and calcite forming simultaneously within monoliths. XRD patterns indicate that geopolymeric monolith is composed of amorphous aluminosilicate phase and calcite and quartz.