• 청정기술
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• 제15권2호
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• pp.91-101
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• 2009

아마이드계 섬유를 고농도로 염색할 때 피염물의 우수한 견뢰도를 얻기 위해 사용되는 금속착염(metal complex) 염료의 대부분은 Cr을 함유하고 있는 유독성 염료이어서, 잔욕에 남게 등의 환경적인 문제를 일으킬 뿐 아니라, $Cr^{6+}$를 함유할 경우 인체에도 심각한 질병을 줄 수 있다. 본 연구에서는 이러한 금속착염 염료를 대체하기 위해 중금속 함유량을 최소화한 반응성 염료를 양모와 나일론 염색에 응용하였다. 각 섬유에 대한 반응성 염료의 염색성을 파악하고, 실제 염색공장에서의 적용을 위해 색상 영역별 흡진률과 견뢰도 수준을 확인하였다. 또한 반응성 염료들에 대한 중금속 함량 및 유해아민분석을 통하여 그 유해성 경향을 수치적으로 검증하며, 기존 사용 염료와의 비교를 통해 미래 지향적인 청정염료로서의 가능성을 보고자 하였다.

• Asian Journal of Atmospheric Environment
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• 제10권4호
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• pp.208-216
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• 2016

This paper reports the results of a field evaluation which used sampling and analytical methods to determine the levels of airborne hexavalent chromium Cr(VI) in major industrial complexes in Korea over a seven year period (2007-2013). Cr(VI) concentrations were determined using cellulose filter sampling and ion chromatography analysis. In order to validate the analytical performance of these methods, studies were also carried out to investigate data quality control (QC) parameters, such as the method detection limit (MDL), repeatability, and recovery efficiencies. The average concentrations of Cr(VI) for the nine industrial complexes in Korea were in the range of 0.09 to $1.40ng/m^3$, which is similar to of the concentrations in other industrial areas around the world. The impacts of Cr(VI) emissions from industrial areas on Cr(VI) concentrations in neighboring-residential areas were considerably low, and the dispersion of Cr(VI) from industrial areas to residential areas was estimated to be 'not-significant'. Cr(VI) levels were not affected by seasonal variation, which suggests that chromium was emitted continuously from the industrial sources throughout the year. The concentration of Cr(VI) measured accounted for 0.7 to 9.4 percent of the total chromium level, which is a low percentage compared to those in other urban areas around the world. This is the first report in an international journal of a field study conducted in Korea to determine the concentration of Cr(VI) in the ambient air of industrial and residential areas.

• 한국표면공학회지
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• 제43권6호
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• pp.297-303
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• 2010

The effect of solution acidity and organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was systematically investigated in the view point of electroreduction of trivalent chromium ions and solution stability. It was found that solution acidity controlled at pH 2.5 showed the widest current range for bright electrodeposits in the presence of PEG additives, which reduced the local current intensification at high current densities. Through complex interaction between PEG additives and hydrogen ion, that is, solution acidity, electrode potential was moved in the negative direction in the bulk solution, while it shifted in the positive when electric potential was scanned. In conjunction with electrochemical quartz crystal microbalance (EQCM), it was found that PEG additives had a role in promoting the electron transfer to trivalent chromium ion complexes in bulk solution and their adsorption at the electrode surface as well as interfering with hydrogen ion reduction process below pH 2.5. The PEG additives developed the nodular morphology during electroreduction of trivalent chromium ions with the increase of solution acidity and enhanced its current efficiency by maintaining the consumption of complexant, formic acid, at low speed.

• Bulletin of the Korean Chemical Society
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• 제26권9호
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• pp.1395-1402
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• 2005

The reaction of cis-[Cr([14]-decane)$(OH)_2]^+$ ([14]-decane = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-teraazacyclotetradecane) with auxiliary ligands {$L_a$ = acetylacetonate (acac), oxalate (ox) or malonate (mal)} leads to a new cis-[Cr([14]-decane)(acac)]$(ClO_4)_2{\cdot}(1/2)H_2O\;(1),\;cis-[Cr([14]-decane)(ox)]ClO_4{\cdot}(1/2)H_2O\;(2)\;or\;cis-[Cr([14]-decane)(mal)]ClO_4{\cdot}(1/4)H_2O\;(3)$. These complexes have been characterized by a combination of elemental analysis, conductivity, IR and Vis spectroscopy, mass spectrometry, and X-ray crystallography. Analysis of the crystal structure of cis-[Cr([14]-decane)(acac)]$(ClO_4)_2{\cdot}(1/2)H_2O$ reveals that central chromium(III) has a distorted octahedral coordination environment and two acetylacetonate-oxygen atoms are bonded to the chromium(III) ion in the cis positions. The angle $N_{axial}-Cr-N_{axial}$ deviates by $11^{\circ}$ from the ideal value of $180^{\circ}$ for a perfect octahedron. The bond angle O-Cr-O between the chromium(III) ion and the two acetylacetonate-oxygen atoms is close to $90^{\circ}$. The bond lengths of Cr-O between the chromium and the acetylacetonate-oxygen atoms are 1.950(3) and 1.954(2) $\AA$. They are shorter than those between chromium and nitrogen atoms of the macrocycle. The IR spectra of 1, 2 and 3 display bands at 1560 {ν (C=O)}, 1710 {${\nu}_{as}$(OCO)} and 1660 $cm^{-1}$ {${\nu}_{as}$(OCO)} attributed to the acac, ox and mal auxiliary ligands stretching vibrations, respectively.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2813-2818
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• 2010

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion ($TBA^+$)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a $100\;{\mu}L$ micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = $1.0{\times}10^{-4}\;M$, [$TBA^+$] = $2.0{\times}10^{-2}\;M$, [$CHCl_3$] = $100.0\;{\mu}L$ and [$ClO_4$] = $2.0{\times}10{-2}\;M$, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

• 대한화학회지
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• 제58권6호
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• pp.681-685
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• 2014

• Applied Biological Chemistry
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• 제33권2호
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• pp.174-176
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• 1990

Oxidation of artemisinic acid was attempted with chromium trioxide-pyridine complex. Epi-Deoxyarteannuin B was formed almost quantitatively, while expected keto artemisinic acid was not the major product. The physical and spectral data of the product are presented(Received March 9, 1990, Accepted May 25, 1990)

• Bulletin of the Korean Chemical Society
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• 제20권8호
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• pp.917-920
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• 1999

The three stereoisomers of the 6,13-bis(thymidinyl)dioxocyclam 6 were synthesized through photoreaction of the chromium alkoxycarbene complex 2 and 1-(benzyloxycarbonyl)-4,4-dimethyl-D 2 -imidazoline. The molecular structure of (R,S)-6 was elucidated by X-ray crystallography.

• Journal of Photoscience
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• 제11권1호
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• pp.19-23
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• 2004

The sharp-line absorption spectrum of microcrystalline samples of cis-[Cr(cycb)$Cl_2$]Cl (cycb=rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been measured between 13000 and $16000 cm^{-1}$ at temperatures down to 5K. The 77K emission and excitation spectra, and 298 K infrared and visible absorption spectra have also been measured. The nine electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using the observed transitions, a ligand field analysis has been performed to probe the ligand field properties of coordinated atoms in the title chromium(III) complex. The zero-phonon line in the sharp-line absorption spectrum splits into two components by $240 cm^{-1}$ , and the $large ^2$$_E{g}$ splitting can be reproduced by the modem ligand field theory. It is confirmed that nitrogen atoms of the macrocyclic cycb ligand have a strong $\sigma$-donor character, but chloride ligand has weak $\sigma$- nd $\pi$-donor properties toward chromium(III) ion.n.

• 대한화학회지
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• 제45권5호
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• pp.436-441
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• 2001

77K에서 mer-[Cr(dien)(glygly)]$ClO_4$의 방출 및 들뜬 상태 스펙트럼과 실온에서 적외선 및 가시선 스펙트럼을 측정하였다. 스핀-허용 및 스핀-금지에 해당하는 12개의 전자 전이의 성분을 배정하였다. 관측한 전이를 이용하여 Cr(Ⅲ) 착물에 배위된 원자의 결합성을 결정하기 위해서 리간드장 해석을 수행하였다. 이 연구에서 dien과 glygly 리간드의 아민 N 원자는 강한 $\sigma$-주개 특성을 갖는 반면에, glygly의 펩티드 N 원자는 Cr(Ⅲ) 이온에 약한 $\pi$-주개의 성질이 있음을 확인할 수 있었다.