We report a new route of akaganéite (β-FeOOH) formation and maghemite (γ-Fe2O3) formation. Akaganéite can be produced by stirring Fe2+ at room temperature for a day under mild conditions. We used FeCl2 ·4H2O as the precursor and mixed it with the Na-rich particle from the oxidation debris solution. The role of the concentration ratio between graphene oxide (GO) and NaOH was addressed to generate oxidation debris (OD) on the surface. In particular, the characterization of OD by transmission electron microscope (TEM) imaging provides clear evidence for the crystal formation of Na-rich particle under electron beam irradiation. For the base treatment process, increasing the concentration of a NaOH in Na-rich solution contributed primarily to the formation of γ-Fe2O3. The characterization by scanning electron microscope (SEM) and TEM showed that the morphology was changed from needle-like to small-oval form. In addition, β-FeOOH can be effectively produced directly using GO combined with FeCl2 ·4H2O at room temperature. More specifically, the role of parent material (Hummer's GO and Brodie's GO) was discussed, and the crystal transformation was identified. Our results concluded that β-FeOOH can be formed in basic and acidic conditions.

In this research, in order to increase the oxidation resistance of graphite, kaolin and alumina powder with different ratios (26A-74S, 49A-51S, 72A-28S) and slurry method were used to create an aluminosilicate coating on the graphite substrate. In order to reduce the difference in the coefficients of thermal expansion of graphite with aluminosilicate coating, aluminum metaphosphate coating as an interlayer was prepared on the surface of graphite by cathodic electrochemical treatment. The isothermal oxidation test of the samples was carried out in air at a temperature of 1250 °C for 1, 3 and 5 h. The microstructure, chemical composition, and phase components of the coating were, respectively, analyzed by scanning electron microscope equipped with an energy-dispersive spectrometer and X-ray diffraction. The results indicated that, by increasing the withdrawal speed of the samples in slurry method, the amount of changes in the weight of the samples has increased and therefore had a direct effect on oxidation. In addition, it was approved that, at high-temperature oxidation, AlPO4 glass phase forms on aluminum metaphosphate interlayer which retards graphite oxidation. Along with aluminum metaphosphate, aluminosilicate coating also produces a glass phase which fills and seals the voids on the surface which prevents the oxygen to reach the surface of graphite. The created double-layer coating including an interlayer of aluminum metaphosphate + slurry coating prepared with the ratio of 26A-74S as the optimal coating in this research was able to increase the oxidation resistance of graphite by 73% at a temperature of 1250 °C.

Activated carbon (AC), extensively used across various industrial sectors, serves as a sponge for different types of gases due to its porous carbon material. These gases are attracted to the carbon substrate via van der Waals forces. In nuclear power plants, AC is commonly used to adsorb radioactive gases such as 86Kr and 134Xe, as well as radioiodine sources like 131I and 133I from gaseous effluents. Even if the adsorbed radioactive gases and radioiodine decay into non-radioactive elements, the spent AC still contains radioactive species with long half-lives, such as 3H (Tritium, T) and 14C (radiocarbon). Minimizing and separating waste that contains long-lived nuclides (e.g., 14C) are pivotal components of an efficient waste management approach. A challenging aspect of effectively managing disposed AC is to minimize long-lived radioactive substances by eliminating them. This paper explores and summarizes the technology used to remove pollutants (3H, 14C) trapped within the pores of Activated carbon through thermochemical vacuum and surface oxidation processes. By recycling and reusing spent Activated carbon, we anticipate a reduction in the volume of radioactive waste, leading to decreased disposal costs. Furthermore, this paper will contribute as a valuable reference in future studies, enhancing the understanding of vacuum thermal desorption and surface oxidation of used Activated carbon.

South It is necessary to develop the future technologies to improve the sustainability and acceptability of nuclear power plants generation. Currently, our company is preparing to build the dry storage facility on-site in accordance with the basic plan for managing high-level radioactive waste announced by the government in 2021. However, studies on technologies for the volume reduction of spent nuclear fuel to increase the efficiency of on-site spent fuel dry storage facilities are very not enough. Accordingly, in this study, the storage efficiency and appropriateness for the SF volume reduction processing technologies such as SF oxide processing technology and consolidation technology are evaluated. Finally, the goal is to develop the optimized technologies to improve the storage efficiency of spent nuclear fuel. As a result in this study is followings. [Safety] After removing volatile fission products (Xe, Kr, I, etc.), Xe, Kr, etc. are removed during storage of the sintered structures. UO2 has a high melting point of approximately 1,000°C after cesium (Cs) has been removed, and heat can be removed by natural convection. [Economy]1999 DUPIC unit facility unit price reference, 2020 standard 328 $/kg estimated. A Comprehensive Approach Considering the Whole System is needed. Benefit from replacement and continuous operation of metal storage containers. Changes in economic efficiency obtained in conjunction with fluctuations in electricity prices and disposal. [Waste filter] A separated solidification facility high-level waste filter is required, and overseas outsourcing must be considered. [Waste cladding]. Cannot be accommodated in low-level disposal site. This reason is why the Ni nuclides occur to be in bulk. [Metal structural material] It is possible to reduce the initial volume by 7.6% or more when compressed or melted, but the technology needs to be advanced. [Oxide blocks] Larger size and density are expected to improve storage and disposal efficiency. [Facilities operation waste] Expected to be able to be disposed of at mid-to-low level decommissioning sites in Gyeongju city. [Solidified volatile nuclides and activated metals] Expected to improve storage efficiency when used volume is reduced and stored, such as outsourced reprocessing. [Oxide block] Radioactivity and decay heat are estimated to be reduced by half during oxide treatment. 75% reduction in volume and 40% reduction in storage area compared to used nuclear fuel before treatment. [Merits/Shortages] Improvement of storage and disposal efficiency empirical research such as large-capacity [real-scale] oxide block production is required. Oxide processing facilities are likely to be classified as post-use nuclear fuel processing facilities. It is determined that additional documents such as a Radiation Environmental Report (RER) must be submitted. Existence of possible external leaks of glass, highly mobile radionuclides from the point of view of nuclear criticality and heat removal. Acceptancy requirements of citizens in the process of creating additional sites for oxide treatment facilities. Considering social public opinion, it is necessary to secure the acceptability such as residents’ opinions convergence. Characteristics of high nuclear non-propagation compared to other processing technologies involving chemical processing. Also, Expectation of volume reduction effect for spent nuclear fuel itself. Volume reduction methods for solid waste and gaseous waste are required.

Cholesterol is prone to oxidation, which results in the formation of cholesterol oxidation products (COPs). This occurs because it is a monounsaturated lipid with a double bond on C-5 position. Cholesterol in foods is mostly non-enzymatically oxidized by reactive oxygen species (ROS)-mediated auto-oxidative reaction. The COPs are found in many common foods of animal-origin and are formed during their manufacture process. The formation of COPs is mainly related to the temperature and the heating time the food is processed, storage condition, light exposure and level of activator present such as free radical. The level of COPs in processed foods could reach up to 1-10 % of the total cholesterol depending on the foods. The most predominant COPs in foods including meat, eggs, dairy products as well as other foods of animal origin were 7-ketocholesterol, 7 α-hydroxycholesterol (7α-OH), 7β-hydroxycholesterol (7β-OH), 5,6α-epoxycholesterol (5,6α -EP), 5,6β-epoxycholesterol (5,6β-EP), 25-hydoxycholesterol (25-OH), 20-hydroxycholesterol (20-OH) and cholestanetriol (triol). They are mainly formed non-enzymatically by cholesterol autoxidation. The COPs are known to be potentially more hazardous to human health than pure cholesterol. The procedure to block cholesterol oxidation in foods should be similar to that of lipid oxidation inhibition since both cholesterol and lipid oxidation go through the same free radical mechanism. The formation of COPs in foods can be stopped by decreasing heating time and temperature, controlling storage condition as well as adding antioxidants into food products. This review aims to present, discuss and respond to articles and studies published on the topics of the formation and inhibition of COPs in foods and key factors that might affect cholesterol oxidation. This review may be used as a basic guide to control the formation of COPs in the food industry.

Bioreactors are devices used by sewage treatment plants to process sewage and which produce active sludge, and sediments separated by solid-liquid are treated in anaerobic digestion tanks. In anaerobic digestion tanks, the volume of active sludge deposits is reduced and biogas is produced. After dehydrating the digestive sludge generated after anaerobic digestion, anaerobic digested wastewater, which features a high concentration of organic matters, is generated. In this study, the decomposition of organic carbon and nitrogen was studied by advanced oxidation process. Ozone-microbubble flotation process was used for oxidation pretreatment. During ozonation, the TOC decreased by 11.6%. After ozone treatment, the TOC decreased and the removal rate reached 80.4% as a result of the Ultra Violet-Advanced Oxidation Process (UV-AOP). The results with regard to organic substances before and after treatment differed depending on the organic carbon index, such as CODMn, CODCr, and TOC. Those indexes did not change significantly in ozone treatment, but decreased significantly after the UV-AOP process as the linkage treatment, and were removed by up to 39.1%, 15.2%, and 80.4%, respectively. It was confirmed that biodegradability was improved according to the ratio of CODMn to TOC. As for the nitrogen component, the ammonia nitrogen component showed a level of 3.2×102 mg/L or more, and the content was maintained at 80% even after treatment. Since most of the contaminants are removed from the treated water and its transparency is high, this water can be utilized as a resource that contains high concentrations of nitrogen.

This study used optical and scanning electron microscopy to analyze the surface oxidation phenomenon that accompanies a γ'-precipitate free zone in a directional solidified CM247LC high temperature creep specimen. Surface oxidation occurs on nickel-based superalloy gas turbine blades due to high temperature during use. Among the superalloy components, Al and Cr are greatly affected by diffusion and movement, and Al is a major component of the surface oxidation products. This out-diffusion of Al was accompanied by γ' (Ni3Al) deficiency in the matrix, and formed a γ'-precipitate free zone at the boundary of the surface oxide layer. Among the components of CM247LC, Cr and Al related to surface oxidation consist of 8 % and 5.6 %, respectively. When Al, the main component of the γ' precipitation phase, diffused out to the surface, a high content of Cr was observed in these PFZs. This is because the PFZ is made of a high Cr γ phase. Surface oxidation of DS CM247LC was observed in high temperature creep specimens, and γ'-rafting occurred due to stress applied to the creep specimens. However, the stress states applied to the grip and gauge length of the creep specimen were different, and accordingly, different γ'-rafting patterns were observed. Such surface oxidation and PFZ and γ'-rafting are shown to affect CM247LC creep lifetime. Mapping the microstructure and composition of major components such as Al and Cr and their role in surface oxidation, revealed in this study, will be utilized in the development of alloys to improve creep life.

강황 분말의 첨가가 마요네즈의 품질특성, 항산화활성 및 산화안정성에 미치는 영향에 대해 평가하였다. 들기름으로 제조된 마요네즈에 강황 분말을 0.5%, 1%, 2%, 3% 농도로 첨가하여 4°C에서 12주 동안 저장하였으며, 강황 분말 무첨가구와 비교하였다. 강황 분말 첨가량이 많아짐에 따라 들기름 마요네즈의 L* (명도) 값은 유의적으로 감소하였고, a* (적색도)는 모든 실험구에서 negative (-)값이었으며, b* (황색도)값은 유의적으로 증가되는 경향이었다(p<0.05). 강황 분말 첨가량이 많아짐에 따라 총 페놀 함량 및 항산화 활성이 유의적으로 증가하였다(p<0.05). 마요네즈를 저장하는 동안 과산화물가는 유의적으로 증가하였으나, 강황 분말 첨가 시료에서는 유의적으로 낮았다(p<0.05). 마요네즈의 유화안정성은 저장 초기에 비해 저장 기간이 길어질수록 감소되는 경향이었으나, 0.5%의 강황 분말 첨가구는 무첨가구에 비해 유의적으로 높은 유화안정성을 보였으며, 1%의 강황 분말 첨가구는 무첨가구와 유의차를 보이지 않았다. 점도는 저장 기간이 경과됨에 따라 감소되었으나, 무첨가구에 비해 1% 이상의 강황 분말 첨가구에서 유의적으로 높았다. 들기름 마요네즈에 강황 분말 첨가 시 항산화 활성 증대 및 과산화물의 생성 억제에 효과적이었으며, 특히 0.5~1% 첨가시 마요네즈의 유화안정성 및 점도 개선에 도움이 될 것으로 판단된다.

본 연구의 목적은 남자 대학 엘리트 조정선수의 2000 m 로잉 에르고미터 수행 후 저온침수 처 치를 통해 혈중 젖산, LDH, MDA 및 SOD의 변화에 긍정적인 영향을 주어 피로 회복에 미치는 영향을 구명하는 데 있다. 이에 남자 대학 엘리트 조정선수 10명을 대상으로 고강도 로잉 에르고미터 2,000 m 수 행 후 비 처치와 저온 침수 처치의 효과를 비교하였다. 측정 변인들에 대한 결과를 검증하기 위해 처치 및 시기 간 상호작용 효과를 분석하기 위해 ANOVA를 실시하였고 각 항목별 유의수준 .05로 설정하여 다음 의 결과를 도출하였다. 젖산은 시기 간 주효과가 나타났고(p<.001) 그룹 내 시기별 차이가 났다(p<.001). 또한, LDH는 그룹 내 시기별 차이가 나타났다(p<.05). MDA는 그룹×시기 간 상호작용 효과가 나타났고 (p<.05), 그룹 간(p<.05), 시기 간(p<.001) 주효과가 나타났다. SOD는 그룹 간, 시기 주효과가 나타났고 (p<.05) 회복 30분 후 그룹 간 차이가 나타났다(p<.05). 이를 종합해 볼 때, 본 연구에서 실시한 저온침수처치가 조정 선수의 혈중 피로 물질, 활성산소 및 항산화 효소에 유의한 효과를 나타냈다. 따라서 운동선수 의 고강도 훈련 후 저온침수를 적극 활용할 것을 권장한다.

Carbon/carbon composites are widely used in re-entry engineering applications thanks to their excellent mechanical properties at high temperatures, but they are easily oxidized in the oxygenated atmosphere. It is important to research their residual mechanical properties influenced by oxidation behaviour, in order to ensure the in-service safety. A microscale degradation model is proposed to predict the oxidation behavior based on the mass conservation and diffusion equations, the derived equivalent steady recession rate of composite is employed to evaluate the residual mechanical properties of the oxidized composite theoretically. A numerical strategy is proposed to investigate the oxidation mechanism of this composite. The differences in the degradation rate between the fiber and the matrix resulted in the steady state and an unchanged shape of the front. Residual mechanical properties of composite with three different domains of oxidation were simulated with a multiscale coupled model. The numerical results demonstrated that the mechanical properties of this composite decreased by 24–32% after oxidation for 30 min at 850 °C. Oxidation also caused the stress redistribution inside components, with the stress concentration diminishing their load-bearing capacity. The local areas of increased stress in the pyrocarbon matrix provided new ways for diffusion of oxygen into the pyrocarbon matrix and fibers.

Volatile organic compounds (VOCs) are a paramount factor in air pollution of the environment. VOCs are vastly present in the wastewater discharged by the pharmaceutical industries. As it is evaporative in nature, it enters the environment spontaneously and causes air pollution, global warming, acid rain and climate change. VOCs must be treated before discharging or any other aerobic methods using an efficient catalyst. As the catalytic oxidation in the liquid phase is facile compared to the gas phase, this study investigated on catalytic liquid-phase oxidation of VOCs in model and real pharmaceutical wastewater. The model compounds of toluene-, ethylbenzene- and chlorobenzene-contaminated waters were treated separately along with the VOCs present in real pharmaceutical wastewater using a tungsten-based carbon catalyst. The tungsten was impregnated on the low-cost activated carbon matrix as it has good selectivity and catalytic property toward VOCs for facile catalytic operations. The metal catalysts were characterised by Fourier transform infrared spectroscopy, X-ray diffraction studies, and scanning electron microscopy with elemental and mapping analysis. The treatability was monitored by total organic carbon, ultra-violet spectroscopy and high-pressure liquid chromatography analysis. The tungsten-impregnated activated carbon matrix (WACM) has a catalytic efficiency toward toluene by 85.45 ± 1.78%, ethylbenzene by 93.9 ± 1.16%, chlorobenzene by 85.9 ± 2.26% and pharmaceutical VOCs by 85.05 ± 1.73% in 20 treatment cycles. The results showed that WACM worked efficiently in VOCs treatment, preventing the environment from air pollution. Furthermore, liquid-phase oxidation could easily be implementable on an industrial scale.

수도권에 위치한 S매립장 내 3개의 매립장을 대상으로 매립가스 배출 및 주요 경로별 표면 발산과 관련된 분석을 하였다. 전체 매립가스 발생비율 10.9%인 LS1이 총 표면발산 비중은 49.4%를 차지하고 있었다. 3개 매립장에서의 메탄의 총 표면발산은 13.6 Nm3/min로서, LS1 8.4 Nm3/min (61.7%), LS2 4.0 Nm3/min(29.4%), LS3 1.2 Nm3/min(8.9%)이고, 발산경로별로는 상부 7.3 Nm3/min (53.2%), 사면 6.4 Nm3/min(46.7%), 다이크 0.02 Nm3/min(0.1%)이었다. 3개 매립장의 주요 배출경로 별 산화율은 다이크가 87.5%로 가장 크고, 상부 72.3%, 사면 71.8% 순이었다. 메탄을 기준으로 표면발 산 기여율은 매립장 별로 LS1이 전체의 61.7%로 가장 컸다. 주요 배출경로별로는 LS1의 사면이 전체의 41.7%, LS2의 상부 24.4%, LS1의 상부 20.0%로서 S매립장의 전체 메탄 표면발산량의 86.1%를 차지함 에 따라 향후 집중적인 관리가 필요할 것으로 판단되었다.

Chemical environments of near-field (Engineered barrier and surrounded host rock) can influence performance of a deep geological repository. The chemical environments of near-field change as time evolves eventually reaching a steady state. During the construction of a deep geological repository, O2 will be introduced to the deep geological repository. The O2 can cause corrosion of Cu canisters, and it is important predicting remaining O2 concentration in the near-field. The remaining O2 concentration in the near field can be governed by the following two reactions: oxidation of Cu(I) from oxidation of Cu and oxidation of pyrite in bentonite and backfill materials. These oxidation reactions (Cu(I) and pyrite oxidation) can influence the performance of the deep geological repository in two ways; the first way is consuming oxidizing agents (O2) and the second way is the changing pH in the near-field and ultimately influencing on the mass transport rate of radionuclides from spent nuclear fuel (failure of canisters) to out of the engineered barrier. Hence, it is very important to know the evolution of chemical environments of near-field by the oxidation of pyrite and Cu. However, the oxidation kinetics of pyrite and Cu are different in the order of 1E7 which means the overall kinetics cannot be fully considered in the deep geological repository. Therefore, it is important to develop a simplified Cu and pyrite oxidation kinetics model based on deep geological repository conditions. Herein, eight oxidation reactions for the chemical species Cu(I) were considered to extract a simplified kinetic equation. Also, a simplified kinetics equation was used for pyrite oxidation. For future analysis, simplified chemical reactions should be combined with a Multiphysics Cu corrosion model to predict the overall lifetime of Cu canisters.

In this paper, we report and discuss the semi-permanently hydrophilic (SPH) treatment of polyester fabric using plasma polymerization and oxidation based on atmospheric pressure dielectric barrier discharge (APDBD) technology. SiOxCy (-H) was coated on polyester fabric using Hexamethylcyclotrisiloxane (HMCTSO) as a precursor, and then plasma oxidation was performed to change the upper layer of the thin film to SiO2-like. The degradation of hydrophilicity of the SPH polyester fabrics was evaluated by water contact angle (WCA) and wicking time after repeated washing. The surface morphology of the coated yarns was observed with scanning electron microscopy, and the presence of the coating layer was confirmed by measuring the Si peak using energy dispersive x-ray spectroscopy. The WCA of the SPH polyester fabric increased to 50 degrees after 30 washes, but it was still hydrophilic compared to the untreated fabric. The decrease in hydrophilicity of the SPH fabric was due to peeling of the SiOxCy(-H) thin film coated on polyester yarns.

High-temperature oxidation of a Ni-based superalloy was analyzed with samples taken from gas turbine blades, where the samples were heat-treated and thermally exposed. The effect of Cr/Ti/Al elements in the alloy on high temperature oxidation was investigated using an optical microscope, SEM/EDS, and TEM. A high-Cr/high-Ti oxide layer was formed on the blade surface under the heat-treated state considered to be the initial stage of high-temperature oxidation. In addition, a PFZ (γ’ precipitate free zone) accompanied by Cr carbide of Cr23C6 and high Cr-Co phase as a kind of TCP precipitation was formed under the surface layer. Pits of several μm depth containing high-Al content oxide was observed at the boundary between the oxide layer and PFZ. However, high temperature oxidation formed on the thermally exposed blade surface consisted of the following steps: ① Ti-oxide formation in the center of the oxide layer, ② Cr-oxide formation surrounding the inner oxide layer, and ③ Al-oxide formation in the pits directly under the Cr oxide layer. It is estimated that the Cr content of Ni-based superalloys improves the oxidation resistance of the alloy by forming dense oxide layer, but produced the σ or μ phase of TCP precipitation with the high-Cr component resulting in material brittleness.

Radioactive mixed waste (RMW) is containing radioactive materials and hazardous materials. Radioactive wastes containing asbestos are include in RMW. These wastes thus must be treated considering both radioactive and hazardous aspects. In this study, a high temperature melt oxidation system consisting of an electric arc furnace and a molten salt oxidation furnace has been developed for the treatment of of radioactive waste containing asbestos. A surrogate waste of the radioactive waste containing asbestos (content of asbestos: 13wt%) was treated in this system. It was melted and fabricated into a glass waste form in the system. Asbestos was not detected in this glass waste form. This means that the asbestos was converted to a glass component in the glass waste form. The waste form was homogeneous glass, and it had a high value of compressive strength (475.13 MPa). It was also confirmed through a leaching test (ANS 16.1) that the waste form had a high chemical durability (Leaching Index > 6). Based on these results, it is considered that the high temperature melt oxidation system will be utilized for the treatment of a significant amount of radioactive waste containing asbestos generated from decommissioning a nuclear power plant.