Jun-Hwan Bang

Effects of sodium laurylsulfate on crystal structure of calcite formed from mixed solutions

Sodium laurylsulfate (SLS), an anionic surfactant, was used for tailoring calcite via a solution route. SLS was dissolved in calcium and carbonate source solutions at various concentrations and critical micelle concentrations (CMCs). The crystallized particles were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), laser-scattering particle size measurements, and thermogravimetric analysis (TGA). Energy dispersive spectroscopy (EDS) analysis was carried out to measure sulfur profiles on the surface of the particles. SLS tended to produce small calcite particles in the carbonate source solution, whereas this effect was not obvious in the calcium source solution. It is believed that the electrostatic repulsion force in the carbonate source solution contributes to the different particle refining effects of SLS seen in the two solutions.

CO 2 Sequestration and Utilization of Calcium-extracted Slag Using Air-cooled Blast Furnace Slag and Convert Slag

Mineral carbonation is a technology in which carbonates are synthesized from minerals including serpentine and olivine, and industrial wastes such as slag and cement, of which all contain calcium or magnesium when reacted with carbon dioxide. This study aims to develop the mineral carbonation technology for commercialization, which can reduce environmental burden and process cost through the reduction of carbon dioxide using steel slag and the slag reuse after calcium extraction. Calcium extraction was conducted using NH4Cl solution for air-cooled slag and convert slag, and ≥ 98% purity calcium carbonate was synthesized by reaction with calcium-extracted solution and carbon dioxide. And we conducted experimentally to minimize the quantity of by-product, the slag residue after calcium extraction, which has occupied large amount of weight ratio (about 80-90%) at the point of mineral carbonation process using slag. The slag residue was used to replace silica sand in the manufacture of cement panel, and physical properties including compressive strength and flexible strength of panel using the slag residue and normal cement panel, respectively, were analyzed. The calcium concentration in extraction solution was analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES). Field-emission scanning electron microscope (FE-SEM) was also used to identify the surface morphology of calcium carbonate, and XRD was used to analyze the crystallinity and the quantitative analysis of calcium carbonate. In addition, the cement panel evaluation was carried out according to KS L ISO 679, and the compressive strength and flexural strength of the panels were measured.