• Journal of the Korean Chemical Society
• /
• v.55 no.3
• /
• pp.472-477
• /
• 2011

The concentration of selenium in grain samples was determined using isotope dilution method in ORC-ICPMS. The experimental conditions were optimized to $H_2$ mode and the flow rate was $4.0\;mL\;min^{-1}$. ORC in $H_2$ mode proved to eliminate most of polyatomic interferences except $BrH^+$ when Br is present in sample matrix. Chemical removal of Br was very difficult and the mathematical correction was successfully employed. The fraction of $BrH^+$ generated from Br at the current experimental condition was 14.1%. The signal on m/z 82 was corrected and calculated for isotope dilution. The analytical reliability of the propose method was successfully evaluated by analyzing the certified standard reference material NIST SRM 1566 and 1567. The method was applied to real samples and the results are $0.034{\pm}0.001\;{\mu}g\;g^{-1}$ for white rice, $0.059{\pm}0.002_5\;{\mu}g\;g^{-1}$ for brown rice, $0.029{\pm}0.001_4\;{\mu}g\;g^{-1}$ for black rice, and $0.034{\pm}0.002\;{\mu}g \;g^{-1}$ for barley. The detection limits ($3\sigma$) for Se was $0.012\;ng\;g^{-1}$.

• Applied Chemistry for Engineering
• /
• v.10 no.5
• /
• pp.696-700
• /
• 1999

The effects and behaviors of heavy metals incoming from industrial by-products were investigated in cement clinker reaction. The raw meal containing 500 ppm of heavy metal ion such as Cu, Cd, Cr, and Pb was calcined at $1450^{\circ}C$ for 30 minutes. Burnability index, fixation concentration of heavy metals in clinker, and apportionment ratio were analyzed. Pb had a minimum fixation concentration of under 5% and Cr had a maximum over 85%. The burnability of Cr containing clinker was lower than that of others as the result of higher value of 3.41% of free lime after calcination at $1450^{\circ}C$. Cu, Cd, and Pb had not any significant effects on the clinker reactitivity. The volatility of heavy metals produced lots of macropores and micropores in clinker and minerals. Cd and Cr were the major apportionments in alite and belite and Cu in interstitial phase. Pb was existed under the detection limit of EDAX analysis due to its higher volatility.

• The Journal of Engineering Geology
• /
• v.23 no.4
• /
• pp.363-373
• /
• 2013

This study investigates the dispersion and behavior of Au and heavy metals in the water system (soil, AMD and stream sediment) at the abandoned Bonjeong gold mine, based on XRD, aqua regia, sequential extraction, and physico-chemical analyses. The XRD analyses targeted quartz and kaolinite in the mine waste soil and quartz and goethite in stream sediment. The physico-chemical analyses of AMD with increasing distance from water system showed that pH increased from 3.00 to 3.19 and Eh decreased from 450 to 396 mV. The Au content in AMD ranged from 0.68 to 0.97 mg/L upstream, but was not detected downstream. The Au content of stream sediment was 13.76 to 22.85 mg/kg. Sequential extraction from stream sediment revealed 10.84% exchangeable (STEP I), 11.09% carbonates (STEP II), 25.53% Fe-Mn oxides (STEP III), 26.62% organic matter (STEP IV), and 24.61% residual (STEP V).

• The Journal of Engineering Geology
• /
• v.29 no.4
• /
• pp.495-508
• /
• 2019

We measured the concentrations of natural radionuclides (uranium and radon) and major elements in groundwater collected from forty wells located in Wonju area to investigate the hydrochemistry and the occurrence of these radionuclides. The range of electrical conductivity (EC) value in the study area was 73~400 μS/cm. In addition to the increase of EC value, the content of cations and anions also tends to increase. Uranium concentrations ranged from 0.06~50.5 ㎍/L (median value, 1.55 ㎍/L) and radon concentrations ranged from 67~8,410 pCi/L (median value, 1,915 pCi/L). Uranium concentrations in 3 well, 7.5% of the samples, exceeded 30 ㎍/L, the maximum contaminant level (MCL) proposed by the US Environmental Protection Agency (EPA), based on the chemical toxicity of uranium. Radon concentrations in 9 wells, 22.5% of the samples, and 1 well, 2.2% of the samples, exceeded 4,000 pCi/L (AMCL of the US EPA) and 8,100 pCi/L (Finland's guideline level), respectively. Concentrations of uranium and radon related to geology of the study area showd the highest values in groundwater of the biotite granite area. Uranium and radon contents in the groundwater are comparatively low compared to those in other countries with similar geological settings. It is likely that the measured value was lower than the actual content due to the inflow of shallow groundwater by the lack of casing and grouting.

• Applied Chemistry for Engineering
• /
• v.28 no.4
• /
• pp.490-494
• /
• 2017

With increasing the number of vehicles, the accident rate also goes up and the damaged vehicles should be painted as a final repair process. At the painting stage the solvent-based paint causes environmental problems. To overcome these problems waterborne refinish paint is frequently used recently. However, for waterborne refinish, the costs of insurance coverage are too expensive, and insurance reimbursement costs could be burdensome. Because of the high price of aquatic paint treatment, the service shop might charge the malicious service price. In this study, the surfactant of Surfynol 104, which is the component in the paint, was used as an indicator whether the vehicle was painted with waterborne paint. The specimen was quantitatively analyzed to contain 0.38% of the surfactant through the standard addition method with isotope substituted internal standard (IS) of fluranthene-d10 by curie point pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS).

• Analytical Science and Technology
• /
• v.9 no.3
• /
• pp.310-319
• /
• 1996

According to the element analysis of Korean Quartz Porphyry, the ignition loss related to porosity was 7.03, 3.36, 2.09 and 0.73% in the order of Suanbo, Yeachen, Angang and Kyongsan. Extraction of minerals in deionized water and elimination effect of heavy metals in water by Quartz Porphyry were examined. When the Quartz Porphyry of the Suanbo, Yeachen of 0.5~2.0% concentration and the Quartz Porphyry of the Angang of 1.5% concentration were immersed and stirred in deionized water for 3 hours at 180rpm, various minerals concentration of the all stirred water were suitable for potable water. But Quartz Porphyry of the Yeachen was not suitable for potable water because of excess extraction of iron. The elimination rate of lead in single solution was 99% by Quartz Porphyry of the Suanbo, Yeachen and Angang of 3% concentration, Cadmium by Quartz Porphyry of the Suanbo of 7% concentration was eliminated about 98% in 1 hour. The copper was significantly eliminated in Quartz Porphyry of low concentration. Especially in Quartz Porphyry of Angang at 0.4% concentration, the rate of ion exchange was 99% in 4 hours. But elimination effect of arsenic in water by Korean Quartz Porphyry was very low.

• Analytical Science and Technology
• /
• v.25 no.6
• /
• pp.460-466
• /
• 2012

An environmentally friendly, so-called green, high performance liquid chromatography method was developed and validated for the determination of trans, trans-muconic acid (t,t-MA) in human urine as a biomarker of benzene exposure. After urinary t,t-MA was extracted and enriched using solid-phase extraction, a MF-Ph1 SG80 ($150mm{\times}2.0mm$ I.D., 5 ${\mu}m$) column with a mobile phase of 10 mM $KH_2PO_4$ containing 0.1% $H_3PO_4$ was used for isocratic separation of t,t-MA with UV detection at 259 nm. The calibration curve was constructed in the range of 0.1-5.0 mg/L with good linearity ($r^2$=0.9992). The intra-day and inter-day precision (as RSD) were 0.9-8.5% and 3.1-4.5%, respectively. The average recovery ranged from 97.5% to 101.7%. The green sample preparation and separation with no organic solvents were successfully achieved. The validated method would be suitable for the routine biological monitoring of benzene exposure in the occupational settings.

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.2
• /
• pp.135-145
• /
• 2015

In order to predict the deterioration of stone monument due to acid fog, an artificial fog test using pH4.0 and pH5.6 was applied to the Gyeongju Namsan granite, decite and marble. After the test had weathered Gyeongju Namsan granite a larger weight reduction due to acid fog than fresh one. Decite has shown the most significant changes among the tested rocks with about 0.005 % of weight reduction. Decite and weathered granite will have considerable weight reduction due to acid rain than the acid fog, whereas the marble was expected to show a weight reduction regardless of the phase of water. The porosity and water absorption rate of weathered granite had significantly increased. This result means that the weathered rock is predicted to be more susceptible to acid fog than the fresh rock. The absorption rate of the marble after the test had shown approximately 50 % increase. The color of the samples had slightly changed towards yellow, such tendency was greater shown in weathered rocks. The marble reacted with acid fog had an increased whiteness. A large amount of cation in the samples is caused mainly by the dissociation of minerals through the reaction with acid fog.

• Resources Recycling
• /
• v.21 no.5
• /
• pp.31-37
• /
• 2012

As a recovery of elemental silicon from the sludge of Si wafer process, a process of mechanical separation-chlorine roasting-electrolysis has been suggested. The silicon sludge consisted of Si, SiC, machine oil, and metallic impurities. The oil and metal impurities was removed by mechanical separation. The Si-SiC mixture was converted to silicon chloride by chlorine roasting at $1000^{\circ}C$ for 1 hr and the silicon chloride was dissolved into an ionic liquid of $[Bmpy]Tf_2N$ as an electrolyte. Cyclic voltammetry results showed an wide voltage window of pure $[Bmpy]Tf_2N$ and a reduction peak of elemental Si from $[Bmpy]Tf_2N$ dissolved $SiCl_4$ on Au electrode, respectively. The silicon deposits could be prepared on the Au electrode by the potentiostatic electrolysis of -1.9 V vs. Pt-QRE. The elemental silicon uniformly electrodeposited was confirmed by various analytical techniques including XRD, FE-SEM with EDS, and XPS. Any impurity was not detected except trace oxygen contaminated during handling for analysis.

• Economic and Environmental Geology
• /
• v.45 no.1
• /
• pp.23-30
• /
• 2012

Major ions and nitrogen isotopic analyses were performed to determine the geochemical characters and to identify the source of nitrate of the shallow groundwater around agricultural field in the Youngdong area. The pH value of groundwater ranges from 60. to 8.2 (pH 7.2, mean). The average of EC, Eh and DO is 369 ${\mu}S/cm$ (70~729 ${\mu}S/cm$), 165.6 mV (29~383.2 mV), 4.3 mg/L (1.8~8.0 mg/L) respectively. The ion concentraion of groundwater was in the order of $Ca^{2+}$>$Na^{2+}$>$Mg^{2+}$>$K^{2+}$ and ${HCO_3}^-$>${NO_3}^-$>${SO_4}^{2-}$>$Cl^-$>$F^-$. Most of groundwater is Ca-$HCO_3$ type. The groundwater was affected by water-rock interaction in the shallow depth. Some groundwater is Ca-Cl or Na-$HCO_3$ (2.5%) type that was due to agricultural activities. The $NO_3$_N concetration of grondwater range from 10.2 mg/l to 26.9 mg/l, which show that this area is under nitrate pollution. ${\delta}^{15}N-NO_3$ value of the groundwater is the origins of are a combination of animal wastes and man-made fertilizers.