• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.2
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• pp.211-217
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• 2024

The growing significance of sustainable energy technologies underscores the need for safe and efficient management of spent nuclear fuels (SNFs), particularly via deep geological disposal (DGD). DGD involves the long-term isolation of SNFs from the biosphere to ensure public safety and environmental protection, necessitating materials with high corrosion resistance for DGD canisters. This study investigated the feasibility of a Cu-Ni film, fabricated via additive manufacturing (AM), as a corrosion-resistant layer for DGD canister applications. A wire-fed AM technique was used to deposit a millimeter-scale Cu-Ni film onto a carbon steel (CS) substrate. Electrochemical analyses were conducted using aerated groundwater from the KAERI underground research tunnel (KURT) as an electrolyte with an NaCl additive to characterize the oxic corrosion behavior of the Cu-Ni film. The results demonstrated that the AM-fabricated Cu-Ni film exhibited enhanced corrosion resistance (manifested as lower corrosion current density and formation of a dense passive layer) in an NaCl-supplemented groundwater solution. Extensive investigations are necessary to elucidate microstructural performance, mechanical properties, and corrosion resistance in the presence of various corroding agents to simplify the implementation of this technology for DGD canisters.

• Resources Recycling
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• v.17 no.6
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• pp.68-78
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• 2008

Using a Pinus koraiensis and Pinus rigida which are normally being discarded in South Korea, optimal conditions of producing activated carbons have been studied to recycle as a higher value-added product. This study consists of two processes, the production process of charcoals from waste timbers by low temperature pyrolysis and the production process of activated carbons from the charcoals by chemical activation reaction. This paper deals with the production process of activated carbons from the charcoals by chemical activation reaction. As an alkali has been generally used as an activating agent, KOH and NaOH which react well with a carbon were used in this study. As a result of the experiments, it is confirmed that activated carbons made with KOH treatment had superior values in physicochemical properties to NaOH, showing that there was no remain of KOH at the surface of the charcoals while there was $3{\sim}4%$ of NaOH remaining after the experiments. Thus, it is concluded that KOH reacted more actively with a charcoal than NaOH. Moreover, it was also found that values in physicochemical properties when using a Pinus koraiensis are superior to the ones when using a Pinus rigida. The optimal mixing ratio of an activating agent to a charcoal was 400 wt.%. To improve the physicochemical properties, activated carbons were washed out by distilled water after neutralization with SM hydrochloric acid solution. When activated carbons were produced from a Pinus koraiensis in this optimal conditions, value of BET surface area was found to be approx. $2400\;m^2/g$.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.630-634
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• 2018

The recovery of paraffin components contained in the fraction as a part of improving the quality for the fraction of waste plastics pyrolysis oil (WPPO) was investigated by batch cocurrent 4 stages equilibrium extraction. The fraction at a distilling temperature of $120-350^{\circ}C$ recovered from WPPO by the simple distillation and a little water-added dimethylformamide (DMF) solution were used as a raw material and solvent, respectively. As the number of equilibrium extraction (n) and the carbon number of paraffin component increased, the concentration of paraffin component contained in the raffinate increased. The concentrations of $C_{12}$, $C_{14}$, $C16$ and $C_{18}$ paraffin components present in the raffinate recovered at n = 4 were about 1.2, 1.5, 1.6 and 1.8 times higher than those of using the raw materials, respectively. Recovery rates (residue rates present in raffinate) of paraffin components rapidly decreased with increasing n, and increased sharply with increasing the carbon number. Furthermore, it was possible to predict the recovery rates at n = 1 - 4 for all paraffin components ($C_7-C_{24}$) contained in the raw material. The raffinate recovered through this study is expected to be used as a renewable energy.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.237-243
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• 2018

The surface chemistry of WCK-AC, WCN-AC and WCZ-AC which are activated carbons prepared from waste citrus peel using KOH, NaOH, and $ZnCl_2$ as activating chemicals were investigated. Also the relationships between the adsorption capacities of the target gases such as acetone, benzene and methyl mercaptan (MM) by the prepared activated carbons and the pore characteristics of each activated carbon were examined. According to XPS analysis of the prepared activated carbons, graphite and phenolic were the main surface functional groups of C1, and the sum of phenol, carbonyl and carboxyl groups increased in the order of WCK-AC > WCN-AC > WCZ-AC. The breakthrough curves obtained from the adsorption experiments for the three target gases in the fixed bed adsorption reactor were well simulated by the empirical equations proposed by Yoon and Nelson. The adsorption capacity for acetone, benzene and MM was larger for activated carbons with the larger sum of surface functional groups. The larger the specific surface area and the pore volume of activated carbons and the smaller the pore size, the better the adsorption performance. In particular, the specific surface area was the best criterion for the adsorption performance of activated carbons used in this study.

• Korean Journal of Environmental Agriculture
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• v.6 no.2
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• pp.46-52
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• 1987

This study of adsorption and column percolation was conducted to examine the utilization of natural zeolite for the removal of heavy metals from waste water to compare with that of absorption activated carbon. The adsorption of heavy metals by natural zeolite was conformed to the Freundlich isotherm (1/n values: $0.12{\sim}0.45$, K values: $18.77{\sim}59.48$) and natural zeolite was turned out to be an effective adsorbent of heavy metals. At the same particle size and percolation velocity, zeolite adsorbed a greater amount of heavy metals was adsorbed on natural zeolite than activated carbon. The smaller the particle size, the more heavy metals that were adsorbed. It was postulated that the most effective size as an adsorbent of heavy metals from waste water ranged from 0.5 to 2.0mm. The slower the percolation velocity that of the heavy metal solution in column, the more heavy metals were adsorbed. Natural zeolite in a single solution adsorbed more heavy metals than that in mixed solution, and the order of the adsorption amount on natural zeolite was Cu>Zn>Cd.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.19-32
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• 2023

This study was conducted to remove fluorine (F) (initial concentration of 9.5 mg/L) from leachate of reclaimed mine waste dump site via different methods: (1) co-precipitation using Ca-based materials; (2) adsorption using activated carbon and fly ash; and (3) coagulation and sedimentation using alum. The F removal efficiencies of each case were estimated as 65.6% (Ca co-precipitation), 27.9% (adsorption of activated carbon), 71.5% (adsorption of fly ash), and 96.6% (alum coagulation and sedimentation). In addition, the applicability of the continuous treatment process using alum coagulation was evaluated by lab-scale experiments using simulated mine drainage containing F of lower (6.4 mg/L) and higher (15.7 mg/L) concentrations, and it was confirmed that the treatment of both cases met the domestic standard (below 3 mg/L) for discharged water in clean areas. Furthermore, the results of bench-scale field tests indicated that the water quality standard of discharged water could be satisfied with the proper operation and management of the process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2491-2502
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• 2014

The main objective of this study is to find out the main fields and methods to create a low carbon green city. Through the findings, we hope to figure out the matters that must be focused on in order to realize a low carbon green city. In order to accomplish this, we organized the main fields and methods of fulfilling this accomplishment by taking a look at recorded documents and past studies related to the creation of low carbon green cities and related concepts. Then a FGI analysis was performed in order to examine suitability and deduct a planning technique. Also, through professional surveys and AHP analysis, we figured out the importance of planning techniques to understand the main characteristics of planning a low carbon green city. We also selected domestic and foreign cases, analysed the actual conditions of applying the deducted planning techniques, and compared the importance of planning techniques in order to see the difference between our plans and real results. 15 planning techniques were deducted and divided into 5 groups. The importance analysis and case analysis showed the following to be the main elements in planning the creation of a low carbon green city: compact high-density development, a traffic system revolving around pedestrians, active utilization of new and renewable energy, and establishment of a recycling system for waste.

• Journal of the Korean Chemical Society
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• v.39 no.7
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• pp.513-523
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• 1995

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are the most concerned toxic organic pollutants to human. Because of their extremely high toxicity and uncertain genotoxic potential, their determination in environmental and biological samples is of great interest. Municipal solid waste incinerator facilities have been reported as the major contributors of dioxins and furans to the environment, and their formation from combustion is a universal phenomenon, everywhere. In this study dioxins and furans were analyzed from the bottom ash produced during combustion in an municipal waste incinerator located in Seoul. The EPA method was modified for sample pretreatment: the soxhlet method was used for extraction and clean-up procedures were performed by using silica and basic alumina, excluding active-carbon. The extract was then analyzed by HRGC/HRMS. A general trend of increase in the amounts of 6∼7 chlorine-substituted dioxins and furans was observed. Total dioxins, furans and 2,3,7,8-TCDD were determined as 8.05 ng/g, 4.75 ng/g, and 6.93 pg/g, respectively.

• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.440-445
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• 2019

It has developed a method that can recover efficiently the reproducible resources from the vehicle waste lithium second battery module. Module cell consists of copper thin film, aluminum thin film and diaphragm made with polymer between these thin films. Cell was disassembled completely without any damage in glove box and through several steps. Preferentially, cathode active material was separated from aluminum thin film at heat treatment of 400 ℃. The retrieved cathode active material was then obtained as high purity after calcining at 800 ℃ to remove residual carbon. Based on this study, it was found that rare metals such as Co, Ni, Mn and Li made up of cathode active material could recover above 80% from aluminum thin film.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.21-26
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• 2001

This study was performed to define the physicochemical characteristics of food waste and food wastewater, and to find the effect of salinity variation experiment, the samples of 1, 2, 3 and 4 were prepared by the salinity of 1.0%, 1.5%, 2.0% and 2.5%, respectively. In experiment, aerobic composting reactors were operated by the model which was composed of half an hour's stirring and 2 hour's aeration per day, for 45 days. Seeds of vegetables of Chinese cabbage and red pepper were seeded at compost-free control, compost 1, 2, 3 and compost 4 for the sake of investigation of germination rate and growth rate of those. The followings are the conclusions that were derived from this study. 1. In food waste, the moisture content was 60%, organic compound content was 95%, total carbon was 47.5%, total nitrogen was 1.6%(therefore, C/N ratio was 30). The values of pH were 4.0 and 3.8 the values of salinity were 0.9% and 1.2%, and the values of conductivity were 7.8 mS/cm and 18.0 mS/cm, respectively. 2. In salinity experiment, the reduction rate of volume was increased(40%) when the salinity was decreased(1.0%). Also, the reduction rate of mass was increased(52%) when the salinity was decreased(1.0%). This fact denotes that salinity hinders the process of composting. 3. Germination rate and growth rate of Chinese cabbage are more excellent than those of red pepper(97.14%, 5.2:2.5 cm). 4. In Chinese cabbage, germination rate and growth rate at compost with the lowest salinity are more excellent than those at compost-free control(97:94%, 5.2:4.5 cm).