• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.15-20
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• 2023

Ionic liquids are considered as a promising, alternative solvent for the electrochemical synthesis of metals because of their high thermal and chemical stability, relatively high ionic conductivity, and wide electrochemical window. In particular, their wide electrochemical window enables the electrodeposition of metals without any side reaction of electrolytes such as hydrogen evolution. The electrodeposition of silver is conducted in 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl) ionic liquid system with a silver source of AgCl. This study is the first attempt to electrodeposit silver nanoparticles without using co-solvents other than [C4mim]Cl. Pulse electrolysis is employed for the synthesis of silver nanoparticles by varying applied potentials from -3.0 V to -4.5 V (vs. Pt-quasi reference electrode) and pulse duration from 0.1 s to 0.7 s. Accordingly, the silver nanoparticles whose size ranges from 15 nm to ~100 nm are obtained. The successful preparation of silver nanoparticles is demonstrated regardless of the kinds of substrate including aluminum, stainless steel, and carbon paper in the pulse electrolysis. Finally, the antimicrobial property of electrodeposited silver nanoparticles is confirmed by an antimicrobial test using Staphylococcus aureus.

• Environmental and Resource Economics Review
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• v.16 no.1
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• pp.129-169
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• 2007

The purpose of this study is to experiment and simulate the newly-updated Second Generation Model for Korea (SGM-Korea). With the updated model, we tried to simulate effect of carbon tax on $CO_2$ emissions and other macroeconomic variables for Korea. The baseline data are compared with projected profiles by various scenarios to evaluate its performance. Our contribution in this study is to having up-graded the model from its earlier version by building new hybrid input-output table based on 2000 input-output and energy balanced tables. According to our estimation, total $CO_2$ emission in Korea has already increased in 2000 to about 1.86 times the 1990 figure. The level of carbon tax required for the current level of $CO_2$ emission to be reduced to the 1995 or 2000 level seems to be too high for Korean economy to bear. It is possible to find a reasonable level of carbon tax, however, if it can combine it with improvement of energy efficiency at the rate of 0.5% to 1% per year. For Korea to meet its obligation to reduce $CO_2$ emissions, therefore, it is imperative for her to improve energy efficiency as well as to develop alternative energy source reducing its dependence on fossil fuel.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.355-362
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• 2009

Fuels based on petroleum will eventually run out in the near future. DME (Di-methyl Ether) is a clean energy source that can be manufactured from various raw materials such as natural gas, coal as well as biomass. As DME has no carbon-carbon bond in its molecular structure and is an oxygenate fuel, its combustion essentially generates no soot as well as no SOx. Because the physical properties of DME are similar to those of LPG, the LPG distribution infrastructure can be converted to use with DME. DME has such high cetane number of 55~60 that it can be used as a diesel engine fuel. Practical use of DME as a next-generation clean fuel or next-generation chemical feedstock is advancing in the fields of power generation, diesel engines, household use, and fuel cells, among others. The purpose of this paper is review the characteristics, standardization, status of research and development in domestic and foreign countries of DME.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.552-561
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• 2018

Biomass, a carbon-neutral resource, is an alternative energy source for exhaustion of fossil fuel and environmental problems. Most of energy production systems using biomass operate with a thermal chemical conversion method. Amongst them, gasification generates syngas and applies to boilers or engines for the production of heat and electricity. However, Tar could be formed during the production of syngas and it is condensed at low temperature which may cause to clog the pipelines and combustion chamber, ultimately resulting in decrease of process efficiency. Thus this work utilized water and oily materials such as soybean oil, waste cooking oil and mineral oil for scrubbing liquid. The removal efficiency of Tar appeared 97%, 70%, 63% and 30% for soybean oil, waste cooking oil, mineral oil and water respectively.

• Resources Recycling
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• v.30 no.4
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• pp.46-53
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• 2021

Biomass can be considered as chemical energy obtained from nature, and includes all living organisms such as plants, animals, and microorganisms. Biomass is eco-friendly, is easily obtainable from the environment, and can be recycled without special treatment processes. Biomass can also be converted into bioenergy fuel through pyrolysis and fermentation. Therefore, it has been considered as a renewable energy source, which prevents the depletion of natural resources such as fossil fuels. In this study, torrefaction to increase the carbon content in various types of biomass sources (sawdust, rice straw, rice bristles, coffee ground, and waste wood) was conducted under an inert atmosphere and at a temperature of 523~573K. The possibility of using torrefied biomass as an alternative to solid fuel for industrial purposes was analyzed by examining the carbon concentration and combustion behaviors.

• Korean Journal of Materials Research
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• v.33 no.12
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• pp.530-536
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• 2023

The theoretical capacity of silicon-based anode materials is more than 10 times higher than the capacity of graphite, so silicon can be used as an alternative to graphite anode materials. However, silicon has a much higher contraction and expansion rate due to lithiation of the anode material during the charge and discharge processes, compared to graphite anode materials, resulting in the pulverization of silicon particles during repeated charge and discharge. To compensate for the above issues, there is a growing interest in SiO_x materials with a silica or carbon coating to minimize the expansion of the silicon. In this study, spherical silica (SiO₂) was synthesized using TEOS as a starting material for the fabrication of such SiO_x through heating in a reduction atmosphere. SiO_x powder was produced by adding PVA as a carbon source and inducing the reduction of silica by the carbothermal reduction method. The ratio of TEOS to distilled water, the stirring time, and the amount of PVA added were adjusted to induce size and morphology, resulting in uniform nanosized spherical silica particles. For the reduction of the spherical monodisperse silica particles, a nitrogen gas atmosphere mixed with 5 % hydrogen was applied, and oxygen atoms in the silica were selectively removed by the carbothermal reduction method. The produced SiO_x powder was characterized by FE-SEM to examine the morphology and size changes of the particles, and XPS and FT-IR were used to examine the x value (O/Si ratio) of the synthesized SiO_x.

• Korean Journal of Materials Research
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• v.28 no.1
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• pp.6-11
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• 2018

There are various manufacturing processes for pure $SiO_2$ that is used as abrasives, chemicals, filters, and glasses, and in metallurgy and optical industries. In the optical fiber industry, to produce $SiO_2$ preform, $SiCl_4$ is utilized as a raw material. However, the combustion reaction of $SiCl_4$ has caused critical environmental issues, such as ozone deficiency by chlorine compounds, the greenhouse effect by carbon dioxide and corrosive gas such as hydrochloric acid. Thus, finding an alternative source that does not have those environmental issues is important for the future. Octamethylcyclotetrasiloxane (OMCTS or D4) as a chlorine free source is recently promising candidate for the $SiO_2$ preform formation. In this study, we first conducted a vaporizer design to vaporize the OMCTS. The vaporizer for the OMCTS vaporization was produced on the basis of the results of the vaporizer design. The size of the primary particle of the $SiO_2$ formed by OMCTS was less than 100 nm. X-ray diffraction patterns of the $SiO_2$ indicated an amorphous phase. Fourier-transform infrared spectroscopy analysis revealed the Si-O-Si bond without the -OH group.

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.102-108
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• 2008

In China, energy and environmental problems are becoming serious owing to rapid economic development. Coal is the most problematic energy source because it causes indoor and outdoor air pollution, acid rain, and global warming. One type of clean coal technology that has been developed is the coal-biomass briquette (or bio-briquette, BB) technique. BBs, which are produced from pulverized coal, biomass (typically, agricultural waste), and a sulfur fixation agent (slaked lime, $Ca(OH)_2$) under high pressure without any binder, have a high sulfur-fixation effect. In addition, BB combustion ash, that is, the waste material, can be used as a neutralization agent for acidic soil because of its high alkalinity, which originates from the added slaked lime. In this study, we evaluated the suitability of alternative biomass sources, namely, aquatic plants, as a BB constituent from the perspective of their use as a source of energy. We selected three types of aquatic plants for use in BB preparation and compared the fuel, handling, and environmental characteristics of the new BBs with those of conventional BBs. Our results showed that air-dried aquatic plants had a higher calorific value, which was in proportion to their carbon content, than agricultural waste biomass; the compressive strength of the new BBs, which depends on the lignin content of the biomass, was high enough to bear long-range intracontinental transport in China; and the new BBs had the same emission control capacity as the conventional BBs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.347-353
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• 2017

In order to prohibit global warming, various kinds of regulatory policies have been established in the whole world. One example is the establishment of the Renewable Portfolio Standard. It requires the increased portion in energy production from renewable energy sources. The Republic of Korea adopted the act on the promotion of the development, use, and diffusion of new and renewable energy since 2012. However, in spite of the effort on the consideration of the renewable energy sources, it was reported the carbon intensity of electricity in Korea was not that low in 2015. Thus, it is required to examine the recent state of the utilization degree of the renewable energy sources in Korea. This paper analyzed the statistical data provided by Korea Power Exchange (KPX) to examine any problems and solutions for generating electricity from the renewable energy sources. We focused on the generation capacity provided by the power plants participated in the market, the electric power trading amount, and the utilization coefficient for 10 years. By analyzing the data, we provide an alternative to solve some imbalance among the factors contributing to renewable energy use.

• Clean Technology
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• v.29 no.3
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• pp.163-171
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• 2023

Hydrogen has been gaining a lot of attention as a possible clean energy source that can aid in reaching carbon neutrality. Currently, hydrogen production has relied on the steam reforming of fossil fuels. However, due to the carbon dioxide emissions caused by this process, hydrogen production based on the steam reforming of bio-oil derived from biomass has been proposed as an alternative approach. In order to use this alternative approach efficiently, one of the key issues that must be overcome is that the complexity of bio-oil, which has a large molecular weight and diverse functional groups of hydrocarbons, promotes the catalytic deactivation of nickel-based catalysts. In this review, research efforts to improve nickel-based catalysts for the steam reforming of bio-oil have been discussed in terms of the active phase, support, and promoters. The active phases are involved in activating C-C and C-H bonds of high-molecular-weight hydrocarbons, and noble and transition metals can be utilized. In terms of the support and promoters, the catalytic deactivation of Ni-based catalysts can be inhibited by utilizing reactive lattice oxygen for support or by suppressing the acidity. The development of active and stable Ni-based reforming catalysts plays a critical role in clean hydrogen production based on bio-oils.