• Korean Journal of Materials Research
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• v.34 no.5
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• pp.254-260
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• 2024

This study is to manufacture a titanium dioxide (TiO₂) photocatalyst by recycling sludge generated using titanium tetrachloride (TiCl₄) as a coagulant. Compared to general sewage, a TiCl₄ coagulant was applied to dyeing wastewater containing a large amount of non-degradable organic compounds to evaluate its performance. Then the generated sludge was dried and fired to prepare a photocatalyst (TFS). Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and nitrogen oxide reduction experiments were conducted to analyze the surface properties and evaluate the photoactive ability of the prepared TFS. After using titanium tetrachloride (TiCl₄) as a coagulant in the dyeing wastewater, the water quality characteristics were measured at 84 mg/L of chemical oxygen demand (COD), 10 mg/L of T-N, and 0.9 mg/L of T-P to satisfy the discharge water quality standards. The surface properties of the TFS were investigated and the anatase crystal structure was observed. It was confirmed that the ratio of Ti and O, the main components of TiO₂, accounted for more than 90 %. As a result of the nitric oxide (NO) reduction experiment, 1.56 uMol of NO was reduced to confirm a removal rate of 20.60 %. This is judged to be a photocatalytic performance similar to that of the existing P-25. Therefore, by applying TiCl₄ to the dyeing wastewater, it is possible to solve the problems of the existing coagulant and to reduce the amount of carbon dioxide generated, using an eco-friendly sludge treatment method. In addition, it is believed that environmental and economic advantages can be obtained by manufacturing TiO₂ at an eco-friendly and lower cost than before.

• Analytical Science and Technology
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• v.37 no.1
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• pp.63-78
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• 2024

The continuous increasing of the global demand of copper and nickel metals raises the interest in developing alternative technologies to produce them from copper sulfide ore. Also, in line with Egypt's vision 2030 for achieving the sustainable socioeconomic development which aims at developing alternative and eco-friendly technologies for processing the Egyptian ores to produce these strategic products instead of its importing. These metals enhance the advanced electrical and electronic industries. The current work aims at investigating the recovery of copper and nickel from Abu Swayeil copper ore using pug leaching technique by sulfuric acid. The factors affecting the pug leaching process including the sulfuric acid concentration, leaching time and temperature have been investigated. The copper ore sample was characterized chemically using X-ray fluorescence (XRF) and scanning electron microscope (SEM-EDX). A response surface methodology develops a quadratic model that expects the nickel and copper leaching effectiveness as a function of three controlling factors involved in the procedure of leaching was also investigated. The obtained results showed that the maximum dissolution efficiency of Ni and Cu are 99.06 % and 95.30%, respectively which was obtained at the following conditions: 15 % H₂SO₄ acid concentration for 6 hr. at 250 ℃. The dissolution kinetics of nickel and copper that were examined according to heterogeneous model, indicated that the dissolution rates were controlled by surface chemical process during the pug leaching. The activation energy of copper and nickel dissolution were 26.79 kJ.mol^-1 and 38.078 kJ.mol^-1 respectively; and the surface chemical was proposed as the leaching rate-controlling step.

• Analytical Science and Technology
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• v.28 no.6
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• pp.398-408
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• 2015

Carbon monoxide (CO) intoxication, arising from CO from an ignited charcoal briquette (ICB), is a popular means of committing suicide in Korea. Most CO intoxications are related to suicide attempts; however, the possibility of a homicide disguised as a suicide cannot be ruled out. Therefore, forensic investigation of the deceased and the crime scene is crucial to confirm that the deceased committed suicide. Detection of the components of an ICB on the objects suspected of being contacted by the deceased, such as the hands, nostrils, and doorknobs, is essential for linking the crime scene to the victim in the case of suicides by ignited ICBs. The traces from an ICB were analyzed by investigating the morphological characteristics and obtaining elemental compositions. The ICBs were completely different from blackened wood, as detected by discriminant analysis with the elements of carbon and oxygen. We analyzed one case of CO intoxication to demonstrate an excellent procedure for verifying whether a suicide occurred with an ICB. We employed SEM-EDX for the analysis of an ICB, microscope-FT/IR and pyrolysis-GC/MS for a partly burnt resin-type substance, GC/MS for diphenhydramine (a sleeping drug), and GC/TCD for the CO-Hb level. We detected traces of an ICB on the hands, nostrils, and doorknobs, which were all discriminated into an ICB group. Detection of ICB traces from the nostrils could indicate that the deceased started the fire themselves to commit suicide. The partially burnt black material was analyzed as an acrylronitrilestyrene polymer, which is normally used to make bags for carrying or wrapping and could be assumed to have been used to transport the ICB. Diphenhydramine, a sleeping drug, was detected at a level of 2.3 mg/L in the blood, which was lower than that in fatal cases (8-31 mg/L; mean 16 mg/L). A CO-Hb level of 79% was found in the blood, which means that the cause of death was CO intoxication. The steps shown here could represent an ideal method for reaching a verdict of suicide by CO intoxication produced by burning an ICB in a sealed room or a car.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.529-536
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• 2011

In this study, we confirmed that the SWRO(Sea Water Reverse Osmosis) production water has more hard corrosiveness than the tap water by fundamental experiment. According to the result, the target of this study was aimed at developing maintenance and anti-corrosion method. In the early stages of the research, batch tests using mild steel coupons and electrochemical experiments were applied to compare the corrosiveness between SWRO production water and the tap water. After then, two corrosion control methods for SWRO production water were applied. Liquid lime($Ca(OH)_2$) and Carbon Dioxide($CO_2$) were inserted and compared with the combination of liquid lime with phosphate corrosion inhibitor and carbon dioxide. The water qualities were evaluated through LSI(Langelier Saturation Index) and proper injection ratio was deduced by the result. Since then, simulated loop system test were performed to evaluate anti-corrosion effect depending on corrosion inhibitors. Subsequently, carbon steel pipes equipped at the loop system were detached for SEM, EDX and XRD analysis to acquire quantitative and qualitative data of the major corrosion products inside the pipes. In conclusion, the controled groups with anti-corrosion techniques applied were effective by appearing 97.4% and 90.9% of improvements in both case of liquid lime and the liquid lime with a phosphate corrosion Inhibitor. furthermore, major components of scale were iron oxides, on the other hand, protective effect of film formation by calcium carbonate($CaCO_3$) could be confirmed.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.394-403
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• 2016

$H_2$ production by chemical looping is an efficient method to convert hydrocarbon fuel into hydrogen with the simultaneous capture of concentrated $CO_2$. This process involves the use of an iron based oxygen carrier that transfers pure oxygen from oxidizing gases to fuels by alternating reduction and oxidation (redox) reactions. The enhanced reactivities of copper oxide doped iron-based oxygen carrier were reported, however, the fundamental understandings on the interaction between $Fe_2O_3$ and CuO are still lacking. In this study, we studied the effect of dopant of CuO to $Fe_2O_3/ZrO_2$ particle on the morphological changes and the associated reactivity using various methods such as SEM/EDX, XRD, BET, TPR, XPS, and TGA. It was found that copper oxide acted as a chemical promoter that change chemical environment in the iron based oxygen carrier as well as a structural promoter which inhibit the agglomeration. The enhanced reduction reactivity was mainly ascribed to the increase in concentration of $Fe^{2+}$ on the surface, resulting in formation of charge imbalance and oxygen vacancies. The CuO doped $Fe_2O_3/ZrO_2$ particle also showed the improved reactivity in the steam oxidation compared to $Fe_2O_3/ZrO_2$ particle probably due to acting as a structural promoter inhibiting the agglomeration of iron species.

• Economic and Environmental Geology
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• v.47 no.2
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• pp.87-96
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• 2014

The objectives of this study were to characterize the physicochemical properties and mineralogy of Hwangto (yellow residual soils) from the southwestern part of Korea and to understand the soil-forming processes of the residual soils from their parent rocks. Both the yellowish residual soils as well as the unweathered and weathered parent rocks were obtained from Jangdong-ri, Donggang-myun, Naju, Jeollanam-do, Korea. The soil samples were examined to analyze the said soil's physicochemical properties such as color, pH, and particle size distribution. A scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis were performed in order to understand the mineralogy, chemical composition, and morphology of the soils. Two thin sections of a parent rock were analyzed to study its mineral composition. A particle size analysis of the soils indicates that the residual soil consists of mainly silt and clay (approximately 95%) and that soil textures are silty clay or silt clay loam. The soil colors of the residual soil are dark brown (7.5YR 3/4) through yellowish red (5YR 4/6). The pH of the residual soil ranges from 4.3 to 5.1. The major minerals of the parent rocks were quartz, biotite, chlorite, and plagioclase. The mineralogy of the sand fraction of the residual soil was quartz, biotite, muscovite and sanidine. The mineralogy of the silt fraction of the residual soil was quartz, biotite, muscovite, Na-feldspar, K-feldspar, and sanidine. The clay mineralogy of the soil was goethite, kaolinite, ilite, hydroxy-interlayed vermiculite(HIV), vermiculite, mica, K-feldspar and quartz. The mineral composition of the residual soil and the parent rock indicates that feldspar and mica in the parent rock weathered into illite, vermiculite and hydroxy-interlayed vermiculite(HIV), and finally changed into kaolinite and halloysite in the yellowish residual soils.

• Resources Recycling
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• v.13 no.1
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• pp.47-53
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• 2004

As a basic study of the re-using molten converter slag as an ordinary portland cement by conversion process, molten slag and sintered CaO pellet was reacted each other. The dissolution rate of the sintered CaO pellet into the molten slag was measured and the changes of the reaction layer was also investigated. The converter slag reagent-grade $SiO_2$ added was melted and hold for 30 minutes in MgO crucible between $1350∼1500 ^{\circ}C$. Then sintered CaO pellet heated at the same temperature was dipped into the molten slag and hold for 10∼30 min. After the reaction, the crucible was cooled in air and the specimen was cut off to the horizontal direction of the crucible. The dissolution rate of CaO pellet was measured by the change of the radius of sintered CaO pellet and the interface layer was observed by SEM/EDX and XRD. The dissolution rate of sintered CaO pellet contacted with the slag of basicity 1 was 9.8 $\mu\textrm{m}$/min at $1350^{\circ}C$ and increased to 18.0 $\mu\textrm{m}$/min at $1500^{\circ}C$. The rate was slightly decreased to 7.6 $\mu\textrm{m}$/min at $1350^{\circ}C$ and 15.0 $\mu\textrm{m}$/min at $V^{\circ}C$ in the slag of basicity 2. The dissolution rate of CaO in converter slag was followed to the rule of Arrhenius' temperature dependency, and the apparent activation energy of the dissolution of CaO was 36 kcal/mole. In case of the slag basicity of 1, the thickness of $C_2$S layer was 64-118 $\mu\textrm{m}$ and the thickness of $C_3$S was 28∼90 $\mu\textrm{m}$ for 10∼30 minutes at $1500^{\circ}C$. And the thickness of the $C_3$S layer was 90∼120 $\mu\textrm{m}$ at the same conditions in the slag basicity of 2.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.771-780
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• 2014

In this study, the various organic supports (i.e., silicone, acrylonitrile-butadiene-styrene, epoxy, and, butadiene rubber) with great sorption capacity of organic contaminants were chosen to develop nano-ZnO/organic composites (NZOCs) and to prevent the detachment of nano-ZnO particles. The water resistance of the developed NZOCs were evaluated, and the feasibility of the developed NZOCs were investigated by evaluating the removal efficiency of 1,1,2-trichloroethylene (TCE) in the aqueous phase. Based on the results from water-resistance experiments, long-term water treatment usage of all NZOCs was found to be feasible. According to the FE-SEM, EDX, and imaging analysis, nano-ZnO/butadiene rubber composite (NZBC) with various sizes and types of porosity and crack was measured to be coated with relatively homogeneously-distributed nano-ZnO particles whereas nano-ZnO/silicone composite (NZSC), nano-ZnO/ABS composite (NZAC), and nano-ZnO/epoxy composite (NZEC) with poorly-developed porosity and crack were measured to be coated with relatively heterogeneously-distributed nano-ZnO particles. The sorption capacity of NZBC was close to 60% relative to the initial concentration, and this result was mainly attributed to the amorphous structure of NZBC, hence the hydrophobic partitioning of TCE to the amorphous structure of NZBC intensively occurred. The removal efficiency of TCE in aqueous phase using NZBC was close to 99% relative to the initial concentration, and the removal efficiency of TCE was improved as the amount of NZBC increased. These results stemmed from the synergistic mechanisms with great sorption capability of butadiene rubber and superior photocatalytic activities of nano-ZnO. Finally, the removal efficiency of TCE in aqueous phase using NZBC was well represented by linear model ($R^2{\geq}0.936$), and the $K_{app}$ values of NZBC were from 2.64 to 3.85 times greater than those of $K_{photolysis}$, indicating that butadiene rubber was found to be the suitable organic supporting materials with enhanced sorption capacity and without inhibition of photocatalytic activities of nano-ZnO.

• Clean Technology
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• v.22 no.2
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• pp.132-138
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• 2016

The emission of SO₂ is inevitable in case of combustion of most fossil fuels except LNG in commercial power plant which has a bad effect on the durability of SCR catalyst. To develop a low temperature SCR catalyst which has a high NOx removal performance and excellent durability to SO₂, V₂O₅/TiO₂ catalysts were prepared by coating on the metal foam substrate with the impregnation amount of Sb₂O₃ as promotor. This study has evaluated the NOx removal performance and the durability to SO₂ on a laboratory scale atmospheric reactor and analyzed the properties of the prepared catalysts by means of porosimeter, BET, SEM (scanning electron microscope), EDX (energy dispersive x-ray spectrometer), XPS (X-ray photoelectron spectroscopy). It was found that the surface area of catalyst increased with the impregnation amount of Sb₂O₃ and the NOx removal performance showed the highest value at the 2 wt% impregnation of Sb₂O₃. This results was considered to be due to the optimum active site on the catalyst surface. And also, Sb₂O₃ impregnated catalysts presented that NOx removal performance was maintained despite the exposure to SO₂ for 5 hours. Therefore it was confirmed that metal foam SCR catalyst for low temperature could be manufactured with the optimum control of Sb₂O₃ impregnation according to the SO₂ presence or not.

• Korean Journal of Heritage: History & Science
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• v.44 no.3
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• pp.112-131
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• 2011

This article reports the results of scientific analysis using SEM-EDX, XRD, TG/DTA, performed on 5 green glaze samples of the brick and roofing tile excavated from the Sacheonwang temple site in Gyeongju in order to verify the chemical compositions and melting temperature. The glaze samples on 2 clay statues have similar chemical composition (PbO 74~81%, $SiO_2$ 14~18%) and melting temperature range ($970{\sim}1070^{\circ}C$), whereas the 2 tiles of goblin's face and 1 rhomb brick have different characteristics. Sample SC 003 (made of PbO 63~67%, $SiO_2$ 25~28%), one of the tiles of goblin's face, shows low melting temperature range (below $970^{\circ}C$), and sample SC 004 (composed of PbO 64~70%, $SiO_2$ 19~25% and melting point $970{\sim}1070^{\circ}C$), the other tile of goblin's face, shows different chemical characteristics compared with 2 clay statues. The green glaze on rhomb brick shows different composition compared with all the others from Sacheonwang temple site in that it does not show any impurity elements other than the main components (PbO 87~88%, $SiO_2$ 12~13%) with very low melting temperature range ($750{\sim}770^{\circ}C$). Surprizingly, the chemical and optical characteristics of this green-glaze on rhomb brick are very similar to that on the bricks from Yeongmyo temple site, Gyeongju. The above results indicate that raw material and manufacturing method are not same for 5 green-glaze samples from Sacheonwang temple site and therefore suggests that further study on the provenance of raw material such as lead isotope analysis is necessary. Our work will provide basic data for future reproduction study of green glazed brick of Sacheonwang temple site, Gyeongju and will also serve as a reference data for the study of raw material and manufacturing method of green glaze from other sites of cultural assets.