초임계 이산화탄소 조건에서 다중벽 탄소 나노튜브(MWCNT)에 공유결합으로 조합된 폴리(2-에티닐피리디 늄 염) 복합체를 제조하였다. 초기 반응 단계에서 MWCNT 표면에서 형성된 4차염화 2-에티닐피리디늄 염의 활성 화된 아세틸렌 삼중 결합이 MWCNT 표면에서 연속적으로 중합되어 폴리(2-에티닐피리디늄 염)이 공유결합으로 조 합된 MWCNT가 용이하게 제조되었다. MWCNT/폴리(2-에티닐피리디늄 염)의 전기 광학 및 전기화학적 특성을 측 정하고 분석하였다. 해당 복합체의 광발광 피크는 2.04 eV의 광자 에너지에 해당하는 610 nm에서 관찰되었다. SnO2:F/TiO2/N719 염료/고체 전해질/Pt 장치가 있는 준고체 DSSC를 MWCNT/P2EP로 제조하였는데, 이의 최대 에 너지 변환효율은 5.33%였다.
노면결빙에 따른 전도사고 및 블랙아이스에 의한 사고 등이 증가하고 있으며 이를 해결하기 위한 발열 시멘트 복합체에 대한 관심이 증가하고 있다. 본 연구에서는 리튬이차전지 산업에서 발생되는 폐 CNT 폐 음극재 등 탄소계 산업부산물을 활용하여 고상탄소 캡슐을 제조 하고 이를 혼입하여 레미탈 및 모르타르 실험체를 제조하여 전기 인압에 따른 중심부 표면 온도 측정 및 열화상 카메라를 통하여 발열 성능을 평가하였다. 고상탄소캡슐 혼입량이 증가할수록 발열 성능이 우수하게 나타났으며 레미탈 실험체의 경우 DC 24 V에서 모든 실험체가 35분 내 표면온도 60℃ 이상 나타내었다. 모르타르 실험체의 경우 전기 인압 DC 24 V에서 고상탄소캡슐을 19% 이상 혼입 시 소요시간 30분 내 30℃ 이상의 발열 상승 목표를 만족하는 것으로 나타났다.
Natural gas pyrolysis produces hydrogen and solid carbon at high temperatures in an oxygen-free environment. This study has evaluated the characteristics of solid carbon obtained from the pyrolysis of methane and natural gas by using molten tin (Sn) at 900–1000 °C. Material characterization outcomes revealed that solid carbon produced at 1000 °C has a spherical morphology. At this temperature, methane and natural gas pyrolysis have resulted in the arrangement of nanocrystalline carbon spheres with average sizes of 635 and 287 nm, respectively. Similarly, pyrolysis at 900 °C and 950 °C has yielded nanocrystalline carbon featuring diverse morphologies such as spheres, fibrous, and irregularly shaped particles. Thermogravimetric analysis revealed that solid carbon products obtained from methane and natural gas pyrolysis at 1000 °C have higher thermal stability compared to commercial carbon black N991. Surface area analysis has indicated that solid carbon from natural gas pyrolysis at 1000 °C has 4.3- and 5.3-times higher surface area compared to the commercial carbon black N991 sample and graphite flakes, respectively. These findings offered insights into optimizing pyrolysis reactor design and operation to generate valuable solid carbon by-products while maximizing hydrogen production.
In this report, we incorporate activated carbon (AC) onto aluminum substrate via doctor blade method to produce an all-solid-state supercapacitor. The electrochemical properties of the all-solid-state supercapacitor were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Galvanostatic charge/discharge tests also were carried out to exhibit stability of the AC-based supercapacitor. The impedance and charge/discharge curves of the all-solid-state supercapacitor showed good capacitive behavior after functionalized AC. The highest specific capacitance obtained for the AC-based supercapacitor was 106 F g−1. About 160% of specific capacitance increased after functionalization of the AC, which indicated that modification of the AC by nitric acid was able to introduce functional groups on the AC and improve its electrochemical performances.
The reduced graphene oxide (rGO)/activated carbon (AC) composites are coated on the aluminum substrate using spray coating technique to fabricate nanocarbon-based supercapacitor. Polymer-based solid-state xanthan-gum/Na2SO4 electrolyte is also introduced to increase stability of the supercapacitor. The electrochemical properties of the supercapacitor are evaluated using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge tests. The highest capacitance value of the rGO/AC composite-based supercapacitor is 120 F/g. The rGO/AC composite-based supercapacitor has also retained ~ 85% of its initial capacitance value after 3000 galvanostatic charge/discharge cycles.
With continuous development in the field of sample preparation technology, solid phase micro-extraction (SPME) has been widely used in analytical chemistry for high extraction efficiency and convenient operation. Different materials lead to different extraction results. Among existing materials, carbon-based materials are still attracting attention from scientists due to their excellent physical and chemical properties as well as their modifiable surfaces, which could enhance the adsorption effects of SPME fiber. This review introduces the preparation methods and applications of different kinds of carbon-based material coatings on fibers. In addition, directions for future research on carbon material composites are discussed.
As a part of the electromagnetic spectrum, microwaves heat materials fast and efficiently via direct energy transfer, while conventional heating methods rely on conduction and convection. To date, the use of microwave heating in the research of carbon-based materials has been mainly limited to liquid solutions. However, more rapid and efficient heating is possible in electron-rich solid materials, because the target materials absorb the energy of microwaves effectively and exclusively. Carbon-based solid materials are suitable for microwave-heating due to the delocalized pi electrons from sp2-hybridized carbon networks. In this perspective review, research on the microwave heating of carbon-based solid materials is extensively investigated. This review includes basic theories of microwave heating, and applications in carbon nanotubes, graphite and other carbon-based materials. Finally, priority issues are discussed for the advanced use of microwave heating, which have been poorly understood so far: heating mechanism, temperature control, and penetration depth.
The present study was conducted to develop persimmon peel, a by-product of dried persimmon manufacturing, as a feed additive via lactic acid bacteria fermentation. Pediococcus pentosaceus, Lactobacillus plantarum, and three strains of Leuconostoc mesenteroides were used as a starter culture in the solid state fermentation of persimmon peel, and antioxidant activity and total polyphenol content were assessed. Leuconostoc mesenteroides KCTC 3100 showed high antioxidant activity (p<0.05), whereas Pediococcus pentosaceus showed high total polyphenol content (p<0.05). These two strains were thus selected as starter culture strains. Glucose, sucrose and molasses were used as variables for optimization and a total 15 experimental runs were produced according to Box-Behnken design. Regarding significant effects of variables, molasses showed linear and square effects on antioxidant activity of persimmon peel fermentation (p<0.05). In conclusion, optimum concentrations of glucose, sucrose, and molasses were determined to be 4.2, 3.9 and 5.3 g/L, respectively, using a response surface model. Antioxidant activity was also improved 2.5 fold after optimization.
유통기한이 7일 밖에 되지 않는 무싹의 저장성 향상을 위해서 고체 이산화탄소를 처리하였다. 이를 위해 고체 이산화탄소의 승화시 발생하는 이산화탄소가스와 극저온의 온도로 농산물에 고이산화탄소 처리와 예냉처리를 동시에 할 수 있는 처리 장치를 개발하였는데 개발된 장치는 처리 대상 작물 주위를 10분만 5℃와 80% 이산화탄소로 조성하였다. 개발된 고이산화탄소 처리 장치를 이용하여 저장 전과 저장 중의 고체 이산화탄소 처리와 저장 전과 저장 중을 모두 한 처리, 그리고 무처리구를 두어 무싹의 저장성을 비교하였다. 고이산화탄소를 처리한 무싹은 25μm ceramic film 포장하여서 8℃에 저장하였다. 무순의 고이산화탄소 처리는 생체중 감소에는 영향을 주지 못하였고 저장 1일 째 포장내 이산화탄소와 산소 농도는 저장 중 처리구에서 40%와 10%로 고이산화탄소 농도를 보였으나 저장 7일째에는 모든 처리구의 이산화탄소 농도는 5% 미만으로 감소하였다. 고농도 이산화탄소 처리는 저장 15일째 에틸렌 농도를 낮추는 효과를 보였으나. 외관상 품질과 이취에서는 효과를 보이지 않았다.
In the present study, the focus is on the analysis of carbothermal reduction of oxide powder prepared from waste WC/Co hardmetal by solid carbon under a stream of argon for the recycling of the WC/Co hard-metal. The oxide powder was prepared by the combination of the oxidation and crushing processes using the waste hardmetal as the raw material. This oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and gases discharge of the mixture during carbothermal reduction was analysed using XRD and gas analyzer. The oxide powder prepared from waste hardmetal has a mixture of . This oxide powder reduced at about , formed tungsten carbides at about , and then fully transformed to a mixed state of tungsten carbide (WC) and cobalt at about by solid carbon under a stream of argon. The WC/Co composite powder synthesized at for 6 hours from oxide powder of waste hardmetal has an average particle size of .
In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of and . This oxide powder was transformed to a mixed state of titanium car-bide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of to and Co, reduction of , to the magneli phase(, n>3), reduction of the mag-neli phase(, n>3) to the (2n3) phases, and reduction and carburization of the (2n3) phases to titanium carbide.
The objective of this research was to estimate the greenhouse gas (GHG) emission factors for food, paper, and wood wastes through methane (CH4) flow analysis. The GHG emissions from a given amount of landfill waste depend on the carbon (C) flows in the waste: (1) carbon storage in landfills, (2) C in carbon dioxide (CO2) and CH4 generated in anaerobic waste decomposition, (3) C in CO2 and CH4 emitted to the atmosphere through vertical gas wells, (4) C in CO2 from CH4 oxidation through cover soils, and (5) C in CH4 emitted to the atmosphere through cover soils. This study reviews the literature on the ranges for DOCf (the fraction of degradable organic carbon that can decompose) and OX (oxidation factor) values of food, paper, and wood, with a particular focus on the role of lignin. There is an inverse relationship between lignin and the DOCf of paper and wood wastes. In this respect, the lignin content could be used as an abatement indicator for the DOCf of paper and wood. The literature review shows that the average DOCf values for food, paper, and wood were 0.72, 0.61, and 0.12, respectively. The country-specific DOCf value for wood (0.44) is significantly higher than the ranges reported in the literature, which implies that the country-specific DOCf for wood can overestimate GHG emissions compared to the DOCf obtained from the literature. The estimated GHG emissions factors were 1,055 kg-CO2e/ ton-wet waste for food, 1,367 kg-CO2e/ton-wet waste for paper, and 276 kg-CO2e/ton-wet waste for wood. Sensitivity analysis results showed that the most influential parameters were MCF (CH4 correction factor), DOCf, and OX. In order to reduce GHG emissions from landfill in Korea, landfill sites currently in operation should be converted from anaerobic to semi-aerobic.
The Intergovernmental Panel on Climate Change (IPCC) recommended the first order decay (FOD) model for estimating methane emissions from solid waste landfills. However, selecting appropriate parameter is a major challenge in methane emission modeling. The degradable organic carbon (DOC) and the fraction of degradable organic carbon which decomposes (DOCF) are the two primary parameters in the methane generation potential (L0). The DOC is the amount of organic carbon that can be decomposed by biochemical reactions in microorganisms. Chemical analysis methods are currently available to measure the DOC including using total organic carbon and element analysis methods. However, chemical analysis methods are not appropriate for determination of the DOC, which indicated that the DOC should be measured by biochemical tests. In addition, these methods should consider a fossil carbon content that needs a complex and high cost of analysis. The DOCF is an estimate of the fraction of carbon that is ultimately degraded and released from landfills. However, no methodology is provided for determination of the DOCF in landfills. Therefore, the purpose of this study was to suggest methodologies for the determination of DOC and DOCF in solid waste landfills. A biochemical methane potential (BMP) test could be used to calculate the DOC because the BMP represents an upper limit on the methane potential of a waste, which corresponds to a maximal amount of degraded organic carbon. The calculation was based on the assumption that the DOCF is 100%. In this study, two methodologies were suggested to determine the DOCF in landfills. The first one uses a new equation (DOCF = 2.76W-0.44) with moisture content in the landfill that actual methane flux data are unavailable. Moisture content is a major ecological parameter on the anaerobic biodegradability of the solid waste in the landfill. Another methodology is to use L0,Landfill/L0,BMP ratio. The L0,Landfill could be determined by a regression analysis if methane flux data were available.
The objective of this study was to assess the affects of various solid waste landfill methods on mass balance of carbon. Four lysimeters simulated a conventional landfill (Lys-A), a landfill recirculated only fresh leachate (Lys-B), and two landfills recirculated leachate after pretreating with ASBR (Lys-C and Lys-D) were operated over 1,600 days. Lys-D was recirculated two times of pretreated leachate volume than that of Lys-C. Mass balance of carbon was calculated considering leachate and biogas production for each lysimeter. Lys-C and Lys-D showed that there was an increase of about 3 times in total amount of COD recovered as methane than Lys-A. This results might be attributable to the activated methanogenic bacteria and the high pH of pretreated leachate. In terms of mass balance of carbon, amount of carbon converted to landfill gas in Lys-B (25.20 g/kg-dry waste) was bigger than that of Lys-A (23.64 g/kg-dry waste), while carbon conversion rate to landfill gas for Lys-A and Lys-B showed 4.80% and 4.71%, respectively. It is assumed that only fresh leachate recirculation method can increase amount of carbon converted to landfill gas resulting from the biodegradation of organic carbon in recirculated leachate. However, in comparison with the conventional landfill method, this method should not accelerate hydrolysis of carbon from the wastes. Carbon conversion rate in the landfill recirculated leachate after pretreating with ASBR was increased due to accelerated anaerobic metabolism processes of the microbes. In Lys-C and Lys-D, about 5.9% of carbon was converted to landfill gas. Therefore, it could be seen that the landfill recirculated leachate after pretreating with ASBR could enhance carbon conversion to landfill gas more than the conventional landfill or the landfill recirculated only fresh leachate.