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        검색결과 5

        1.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pyrolysis fuel oil (PFO) is used for the manufacturing of high-purity pitch for carbon precursor due to its high carbon content, high aromaticity, and low heterogeneous element and impurity content. Pitch is commonly classified with its softening point, which is most considerable physical property affecting to various characteristics of the carbon materials based on pitch, such as electrical and thermal conductivity, mechanical strength, and pore property. Hence, the softening point should be controlled to apply pitch to produce various carbon materials for different applications. Previous studies introduce reforming process under high pressure and two step heat treatment for the synthesis of pitch with high softening point from PFO. These methods lead to a high process cost; therefore, it is necessary to develop a process to synthesize the pitch with high softening point by using energy effective process at a low temperature. In this study, waste polyethylene terephthalate (PET) was added to control the softening point of PFO-based pitch. The pitch synthesized by the heat treatment with the addition of PET showed the softening point higher than that of the pitch synthesized with only PFO. The softening point of PFObased pitch synthesized at 420 °C was 138.3 °C, while that of the pitch synthesized by adding PET under the same process conditions was 342.8 °C. It is proposed that the effect of the PET addition on the increase in the softening point was due to the radicals generated from thermal degradation of PET. The radicals from PET react with the PFO molecules to promote the polymerization and finally increase the molecular weight and softening point of the pitch. In addition, activated carbon was prepared by using the pitch synthesized by adding PET, and the results showed that the specific surface area of the activated carbon increased by the addition of PET. It is expected that the pitch synthesis method with PET addition significantly contributes to the manufacture of pitch and activated carbon.
        4,000원
        2.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, magnetite (Fe3O4) nanoparticles were electrochemically synthesized in an aqueous electrolyte at a given potential of -1.3 V for 180 s. Scanning electron microscopy revealed that dendrite-like Fe3O4 nanoparticles with a mean size of < 80 nm were electrodeposited on a glassy carbon electrode (GCE). The Fe3O4/GCE was utilized for sensing chloramphenicol (CAP) by cyclic voltammetry and square wave voltammetry. A reduction peak of CAP at the Fe3O4/GCE was observed at 0.62 V, whereas the uncoated GCE exhibited a very small response compared to that of the Fe3O4/GCE. The electrocatalytic ability of Fe3O4 was mainly attributed to the formation of Fe(VI) during the anodic scan, and its reduction to Fe(III) on the cathodic scan facilitated the sensing of CAP. The effects of pH and scan rate were measured to determine the optimum conditions at which the Fe3O4/GCE exhibited the highest sensitivity with a lower detection limit. The reduction current for CAP was proportional to its concentration under optimized conditions in a range of 0.09-47 μM with a correlation coefficient of 0.9919 and a limit of detection of 0.09 μM (S/N=3). Moreover, the fabricated sensor exhibited anti-interference ability towards 4-nitrophenol, thiamphenicol, and 4-nitrobenzamide. The developed electrochemical sensor is a cost effective, reliable, and straightforward approach for the electrochemical determination of CAP in real time applications.
        4,000원
        3.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porous materials play a vital role in science and technology. The ability to control their pore structures at the atomic, molecular, and nanometer scales enable interactions with atoms, ions and molecules to occur throughout the bulk of the material, for practical applications. Three-dimensional (3D) porous carbon-based materials (e.g., graphene aerogels/hydrogels, sponges and foams) made of graphene or graphene oxide-based networks have attracted considerable attention because they offer low density, high porosity, large surface area, excellent electrical conductivity and stable mechanical properties. Water pollution and associated environmental issues have become a hot topic in recent years. Rapid industrialization has led to a massive increase in the amount of wastewater that industries discharge into the environment. Water pollution is caused by oil spills, heavy metals, dyes, and organic compounds released by industry, as well as via unpredictable accidents. In addition, water pollution is also caused by radionuclides released by nuclear disasters or leakage. This review presents an overview of the state-of-the-art synthesis methodologies of 3D porous graphene materials and highlights their synthesis for environmental applications. The various synthetic methods used to prepare these 3D materials are discussed, particularly template-free self-assembly methods, and template-directed methods. Some key results are summarized, where 3D graphene materials have been used for the adsorption of dyes, heavy metals, and radioactive materials from polluted environments.
        4,500원
        4.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        One of the issues currently facing nuclear power plants is how to store spent nuclear waste materials which are contaminated with radionuclides such as 134Cs, 135Cs, and 137Cs. Bioremediation processes may offer a potent method of cleaning up radioactive cesium. However, there have only been limited reports on Cs+ tolerant bacteria. In this study, we report the isolation and identification of Cs+ tolerant bacteria in environmental soil and sediment. The resistant Cs+ isolates were screened from enrichment cultures in R2A medium supplemented with 100 mM CsCl for 72 h, followed by microbial community analysis based on sequencing analysis from 16S rRNA gene clone libraries (NCBI’s BlastN). The dominant Bacillus anthracis Roh-1 and B. cereus Roh-2 were successfully isolated from the cesium enrichment culture. Importantly, B. cereus Roh- 2 is resistant to 30% more Cs+ than is B. anthracis Roh-1 when treated with 50 mM CsCl. Growth experiments clearly demonstrated that the isolate had a higher tolerance to Cs+. In addition, we investigated the adsorption of 0.2 mg L-1 Cs+ using B. anthracis Roh-1. The maximum Cs+ biosorption capacity of B. anthracis Roh-1 was 2.01 mg g-1 at pH 10. Thus, we show that Cs+ tolerant bacterial isolates could be used for bioremediation of contaminated environments.
        4,000원
        5.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        전 세계적으로 원자력 발전소는 442기가 가동 중이며, 62기가 충원될 예정이다. 원자력 발전소의 증가에 따라 방사성 폐기물 유출에 대한 위험성도 증가하였다. 이러한 이유 때문 에, 방사성 폐기물의 처리는 인간, 동물, 식물을 포함하는 자 연 생태계를 보전하는 관점에서 중요하다. 또한, 방사성 폐 기물 유출은 그 지역뿐만 아니라 전 세계적으로 심각한 문 제를 야기한다. 본 연구는 입체 배양세포에 방사성 핵종원 소 (세슘, 스트론튬, 코발트)를 처리하였고 이에 대한 영향력 을 확인하였다. 입체 배양 구조체는 아가로오스 하이드로겔 을 이용하여 제작했으며 암세포 및 정상세포 (HeLa, HepG2, COS-7)를 사용하여 입체 배양을 실시 하였다. 입체 형태로 세포를 배양한 후 세슘, 스트론튬, 코발트 농도 변화에 따라 세포 생존능력을 분석하였다. 이때 입체 배양세포에서 생존 능력이 단층 배양세포 보다 최대 42% 우수한 것을 확인하였 다. 입체 배양구조체는 세포가 형태 및 생리학적으로 in vivo 환경인 조직과 비슷하게 배양을 가능하게 하였다. 따라서, 입체 배양구조체는 기존의 단층 배양 한계점인 in vivo 환경 에 적용시킬 수 없다는 한계를 극복하였다. 본 입체 배양 기 술이 중금속 독성평가 및 단시간 내에 다수의 물질 분석을 수행하는 고속 대량 스크리닝 기술에 활용될 것으로 기대한 다.
        4,000원