• 한국환경보건학회지
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• 제46권2호
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• pp.159-169
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• 2020

Objectives: The purpose of this study was to investigate changes among the nine kinds of reduction chemical substances in Korea over the period of 2008-2017. We will define basic data for improving the management methods for reducing chemical substances. Methods: A survey of hazardous pollutant emissions for 2008-2017 was conducted through the pollutant Release and Transfer Register homepage. Nine kinds of designated reduction chemical substances (Benzene, Vinyl chloride, Trichloro ethylene, 1,3-butadiene, Dichloro methane, Tetrachloro ethylene, N,N-dimethylformamide, Acrylo nitrile, and Chloroform) provided the study subjects. The emission of hazardous chemicals and health effects used the National Health Statistics and Integrated Chemicals Information System (ICIS) as a reference. Results: Hazardous pollutant emissions increased by 1.2 times over the past decade, and nine types of reduction chemical substances increased by 1.6 times. By region, the emissions of reduction chemical substances over the last 10 years were in the order of Chungbuk, Gyeonggi, and Gyeongbuk. Emissions of Dichloro methane was the highest in Chungbuk and Gyeongbuk. N,N-dimethylformamide was the highest in Gyeonggi. Carcinogen pollutant emissions showed a tendency to increase continuously. In addition, group 1 carcinogen emissions showed a tendency to decrease. Conclusion: In the last decade, the amount of hazardous chemical emissions has been continuously increasing. Hazardous chemical emissions require facility improvement for continuous emissions reduction. More research on reduction of emissions is needed.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3691-3695
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• 2012

Photocatalytic reduction of hexavalent chromium (Cr(VI)) in ferric-tartrate system under irradiation of visible light was investigated. Effects of light resources, initial pH value and initial concentration of various reactants on Cr(VI) photocatalytic reduction were studied. Photoreaction kinetics was discussed and a possible photochemical pathway was proposed. The results indicate that Fe(III)-tartrate system is able to rapidly and effectively photocatalytically reduce Cr(VI) utilizing visible light. Initial pH variations resulte in the concentration changes of Fe(III)-tartrate complex in this system, and pH at 3.0 is optimal for Cr(VI) photocatalytic reduction. Efficiency of Cr(VI) photocatalytic reduction increases with increasing initial concentrations of Cr(VI), Fe(III) and tartrate. Kinetics analysis indicates that initial Fe(III) concentration affects Cr(VI) photoreduction most significantly.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1658-1660
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• 2009

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.100-103
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• 2010

In this study, NO reduction behaviors of copper-loaded mesoporous molecular sieves (Cu/MCM-41) have been investigated. The Cu loading on MCM-41 surfaces was accomplished by a chemical reduction method with different Cu contents (5, 10, 20, and 40%). $N_2/77$ K adsorption isotherm characteristics, including the specific surface area and pore volume, were studied by BET's equation. NO reduction behaviors were confirmed by a gas chromatography. From the experimental results, the Cu loading amount on MCM-41 led to the increase of NO reduction efficiency in spite of decreasing the specific surface area of catalysts. This result indicates that highly ordered porous structure in the MCM-41 and the presence of active metal particles lead the synergistical NO reduction reactions due to the increase in adsorption energy of MCM-41 surfaces by the Cu particles.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2167-2170
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• 2013

A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.

• Bulletin of the Korean Chemical Society
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• 제22권10호
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• pp.1089-1092
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• 2001

• Korean Chemical Engineering Research
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• 제55권3호
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• pp.379-384
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• 2017

LiCl 용융염에서 희토류 산화물의환원율을 높이기 위해 NiO와 혼합하여 전해환원을실시하였다. Cyclic voltammetry (CV) 실험을 통해 LiCl 용융염 내에서 혼합산화물의 전기화학적 환원거동을 조사하였다. 혼합산화물로 제작된 환원전극과 그라파이트 산화전극 사이에 일정한 작동전압을 인가하여 이론전하량 대비 다양한 전하량을 공급한 후 중간생성물의 결정구조를 XRD를 이용하여 분석하였다. NiO 산화물을 첨가함으로써 전기전도성이 좋은 Ni 금속 주위로 희토류 산화물이 환원되어 RE-Ni 합금형태의 금속으로 완전히 전환되었으며, 합금을 형성하는 반응 메커니즘을 제시하였다.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2321-2326
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• 2018

We evaluated the optimal conditions for fluidization of nickel oxide (NiO) and its reduction into high-purity Ni during hydrogen reduction in a laboratory-scale fluidized bed reactor. A comparative study was performed through structural shape analysis using scanning electron microscopy (SEM); variance in pressure drop, minimum fluidization velocity, terminal velocity, reduction rate, and mass loss were assessed at temperatures ranging from 400 to $600^{\circ}C$ and at 20, 40, and 60 min in reaction time. We estimated the sample weight with most active fluidization to be 200 g based on the bed diameter of the fluidized bed reactor and height of the stocked material. The optimal conditions for NiO hydrogen reduction were found to be height of sample H to the internal fluidized bed reactor diameter D was H/D=1, reaction temperature of $550^{\circ}C$, reaction time of 60 min, superficial gas velocity of 0.011 m/s, and pressure drop of 77 Pa during fluidization. We determined the best operating conditions for the NiO hydrogen reduction process based on these findings.

• 분석과학
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• 제25권6호
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• pp.339-344
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• 2012

In this research, hydride generation in HPLC-ICPMS for the selenium speciation was investigated. Chemical and photochemical vapor generation techniques were compared for the effective generation of selenium vapour. $HBr/KBrO_3$ was used for the chemical reduction and a UV lamp was used for the photochemical reduction. It was found out that the photochemical reduction was more effective than the chemical reduction in all of selenium species studied. The optimum conditions for the generation of vapour are 0.4% KI, 2.5% $NaBH_4$, and 1.0 M HCl. The enhancement factor using a photochemical hydride generation was from 6.3 to 16.7 times for inorganic and organic selenium species.