• Resources Recycling
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• v.19 no.3
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• pp.45-51
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• 2010

Solvent extraction behavior of Sn(IV) from hydrochloric acid solution was investigated using TBP(Tri-butyl Phosphate) as an extractant. The experimental parameters, such as the concentration of HCl solution, chloride ions, extractant, and Sn were observed. Experimental results showed that the extraction percent of Sn was increased with increasing the hydrochloric acid and chloride ion concentration. More than 98% of Sn was extracted in 7.0 M HCl by 10% TBP. The optimum extraction stages of Sn for continuous extraction process was theoretically calculated by analysizing the McCabe-Thiele diagram. Stripping of Sn from the loaded organic phases can be accomplished by NaOH as a stripping reagent effectively and 99.3% of Sn was stripped by 2.0M NaOH solution.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.146.2-146.2
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• 2014

KIST 6MV 가속기는 이온빔 분석 그리고 가속기 질량 분석법(Accelerator mass spectrometry)으로 활용된다. 이온빔 분석으로는 RBS, TOF ERD, PIXE. ${\mu}$-Probe을 할 수 있으며 AMS(Accelerator mass spectrometry)는 액체섬광측정법(LSC)과 비교할때 민감도는 1,000배 정도로 3H, 14C, 26Al,41Ca 을 10-21 ~ 10-18 mole/mg 까지 검출 가능하여. 응용분야로는 BAMS(Biological AMS), 전통과학, 지구과학, 환경과학에 활용되고 있다. 이중 AMS의 생-의학분야(BAMS)의 응용은 최근 매우 중요하게 연구되고 있다. BAMS의 활용 연구에 사용하는 핵종으로는 주로 3H, 14C, 41Ca, 36Cl를 사용하며, 14C 화합물은 쉽게 구할 수 있고, 자연방사선 이하의 낮은 14C labeled drug 사용하기 때문에 1948년 이후 생물학 연구에 혁신적으로 활용되고 있다. 주 활용분야로는 (1) 신약개발은 임상실험 전(Phase 0) 이용되며, 14C로 표지된 bio-molecule을 자연수준의 방사선 농도에서 추적자로 사용하여 질량을 측정하는 방법을 활용. (2) 의과학분야는 인체 내에서의 추적자 연구수행 (3) 항암제 연구는 암조직 중 약물농도와 암효과의 상관성을 연구 (4) 바이오 기술 분야에서는 생약 유효물질의 체내 대사연구 등을 할 수 있어 전세계적으로 활발히 연구가 진행되고 있다. KIST에서는 6MV가속기를 BAMS 연구에 활용하기 위하여 전처리 단계의 Combustion, Gas transfer, Reduction 등을 자체 제작하여 테스트 중에 있으며, BAMS 샘플의 Gas는 호기중의 성분, 대기 성분이 있으며, Liquid는 혈액(혈장,혈청,적혈구), Solid는 DNA, 세포, 장기 뼈, 피부, 식물조직, 사료, Drug 및 그 대사 류가 있다. AMS 측정 결과는 14C/12C 비율로 나타나며 그 결과를 농도로 환산하여 분석하게 된다. 또한 분석 데이터 신뢰를 확보하기 위하여 표준시료 및 품질관리용 시료를 사용하여 BAMS분석법에 대한 검증을 실시하였다.

• Clean Technology
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• v.28 no.1
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• pp.38-45
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• 2022

CuCl₂-loaded V₂O₅-WO₃/TiO₂ catalyst showed excellent activity in the catalytic oxidation of elemental mercury to oxidized mercury even under SCR condition in the presence of NH₃, which is well known to significantly inhibit the oxidation activity of elemental mercury by HCl. Moreover, it was confirmed that, when SO₂ was present in the reaction gas together with HCl, excellent elemental mercury oxidation activity was maintained even though CuCl₂ supported on the catalyst surface was converted to CuSO₄. This is thought to be because not only HCl but also the SO₄ component generated on the catalyst surface promotes the oxidation of elemental mercury. However, in the presence of SO₂, the total mercury balance before and after the catalytic reaction was not matched, especially as the concentration of SO₂ increased. In order to understand the cause of this, further studies are needed to investigate the effect of SO₂ in the SnCl₂ aqueous solution employed for mercury species analysis and the effect of sulfate ions generated on elemental mercury oxidation. It was confirmed that SO₂ also promotes NO_x removal activity, which is thought to be because the increase in acid sites by SO₄ generated on the catalyst surface by SO₂ facilitates NH₃ adsorption. The composition change and structure of the components present on the catalyst surface under various reaction conditions were measured by XRD and XRF. These measurement results were presented as a rational explanation for the results that SO₂ enhances the oxidation activity of elemental mercury and the NO_x removal activity in this catalyst system.

• The Korean Journal of Food And Nutrition
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• v.10 no.4
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• pp.503-508
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• 1997

The extraction and separation methods of protein-bound polysaccharides from the mycelium and culture broth of L. edodes were investigated. The use 2% solution of surface active agent, Triton X-100 was effective for extraction of the protein-bound polysaccharide from the mycelium. The extraction of the protein-bound polysaccharides from mycelium with hot water was achieved by 4 hours extraction at 10$0^{\circ}C$. For the separation and partial purification of the protein bound polysaccharides the column chromatography using DEAE-Cellulose, DEAE-Sephadex and Sephadex proved to be effective.

• Analytical Science and Technology
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• v.29 no.1
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• pp.19-28
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• 2016

The objective of this study was to determine the acidification of precipitation in the Jeju area. Precipitation samples were collected from the Jeju area from 2009-2014, and the major ionic species were analyzed. In the regression analysis, through a comparison of ion balance, electric conductivity, and acid fraction, the correlation coefficients showed a good linear relationship within the range of 0.927~0.983. The volume-weighted means of the pH and electric conductivity were 4.9 and 22.7 µS/cm, respectively. The ionic strength of precipitation was 0.27±0.38 mM, indicating about 35.9 % of total precipitation within the pure precipitation criteria. The volume-weighted mean concentrations (ìeq/L) of the ionic species in the precipitation were in the order of Na⁺ > Cl⁻ > nss-SO₄²⁻ > NO₃⁻ > NH₄⁺ > Mg²⁺ > H⁺ > nss-Ca²⁺ > PO₄³⁻ > K⁺ > HCOO⁻ > CH₃COO⁻ > NO₂⁻ > F⁻ > HCO₃⁻ > CH₃SO₃⁻ . The acidification contributions by sulfuric and nitric acids were 54.5 % and 36.5 %, respectively. Meanwhile the acidification contributions by formic and acetic acids were 4.8 % and 4.2 %, respectively. Thus, it was found that the acidification of the precipitation in the Jeju area was mainly due to the inorganic acids. The neutralization factors by NH₃ and CaCO₃ were also 33 % and 20 %, respectively.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.263-271
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• 1995

Chemical assessment of soil pollution with heavy metals was made by analyzing the changes in pH, ionic strength, cationic concentration and chemical species in the soil solution. Saturated pastes of the unpolluted soils were made by adding solutions containing Cu or Cd and the final Cu or Cd concentrations were in the range of 0 to 400 mg/kg. After equilibrating for 24 hours at $25^{\circ}C$, the soil solution was extracted from the saturated pastes by the vacuum extraction method and analyzed for pH, electrical conductivity, Cu, Cd, cations and inorganic ligands. Chemical species in soil solution were calculated by the GEOCHEM-PC program employing the input variables of pH, ionic strength(${\mu}$), molar concentrations of cations and ligands. Increasing Cu or Cd additions lowered pH of the soil solution but increased concentrations of Ca, Mg and K resulting in increases of ${\mu}$ of the soil solution. Effects of Cu on lowering pH and increasing ${\mu}$ were greater than those of Cd. Concentrations of Cu or Cd in soil solution were relatively very low as compared to those of additions, but increased linearly with increasing additions representing that concentrations of Cu were higher than those of Cd. At 400 mg/kg additions, concentrations of Cu were in the range of 0.51 to 11.70 mg/L but those of Cd were 34.4 to 88.5 mg/L. Major species of Ca, Mg and K were free ions and these species were equivalent to greater than 95 molar % of the existing respective molar concentrations. These cationic species were not changed by Cu or Cd additions. Major species of Cu in lower pH soils such as SiCL and SL were free $Cu^{2+}$ (>95 molar %), but those in LS having a higher pH were free $Cu^{2-}$ and Cu-hydroxide complex. At 100 mg Cu/kg treatment, $Cu^{2+}$ and Cu-hydroxide complex were equivalent to 73 and 22.4 molar %, respectively. These respective percentages were decreased and increased correspondingly with increasing Cu treatments. Major species of Cd in soil solution were free $Cd^{2+}$ and Cd-chloride complex, representing 79 to 85 molar % for $Cd^{2+}$ and 13 to 20% for Cd-chloride complex at 10 mg Cd/kg treatment. With increasing Cd additions to 400 mg/kg, $Cd^{2+}$ species decreased to $40{\sim}47%$ but Cd-chloride complexes increased to $53{\sim}60$ molar %. These results demonstrated that soil contamination with heavy metals caused an adverse effect on the plant nutritional aspects of soil solution by lowering pH, increasing cations temporarily, and increasing free metal concentrations and species enough to be phytotoxic.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.239-244
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• 2008

To evaluate the acidity and chemical characteristics of rainwater in Korea, its pH and ion concentrations were investigated in Suwon from April to December, 2006. In addition, to estimate the contribution of ions on its acidity, ion composition and neutralization effect of major cations were investigated. Ion balance and electrical conductivity balance between measured and estimated values showed a high correlation. The mean pH and EC in rainwater collected during the investigation periods were 4.7 and $17.6{\mu}S\;cm^{-1}$, respectively. The monthly variation in EC showed a clear seasonal pattern, which had the lowest value of $9.1{\mu}S\;cm^{-1}$ in July and increased remarkably in November. $Na^+$ was the most abundant cation and followed by $NH_4{^+}>Ca^{2+}>H^+>Mg^{2+}>K^+$. Among them, $Na^+$ and $NH_4{^+}$ accounted for more than 65% of the total cations. In case of anions, the relative abundance was $SO_4{^{2-}}>NO_3{^-}>Cl^-$. About 67% of the total anions in rainwater was $SO_4{^{2-}}$, which showed $119.0{\mu}eq\;L^{-1}$ as mean value during the monitoring periods. Furthermore, 94% of the soluble sulfate in rainwater was identified as nss-$SO_4{^{2-}}$(non-sea salt sulfate). We also found that $NH_4{^+}$ and $Ca^{2+}$ contributed greatly in neutralizing the rain acidity, especially in dry season.

• Food Science and Preservation
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• v.21 no.4
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• pp.520-528
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• 2014

The purpose of this study was to evaluated a phthalate, heavy metal contents and physicochemical quality properties in korean mudflat solar salt and foreign salts. DEHP in mudflat solar salt (MSS) was detected a low level (9.00~669.89 ppb), but it was shown a high level excess to 1.5 ppm criteria in the foreign solar salt (FSS) 5 type (3,440.64, 3,266.56, 2,189.65, 4,010.69, 4,554.20 ppb) and foreign large solar salt (FLSS) 1 type (1,983.27 ppb). Also, DEHP in FSS 2 type (930.15, 1,310.07 ppb) and FLSS 1 type (924.92 ppb) was detected a high level not excess to criteria. No detected DMP, DEP, DIBP, DBP, DAP, BBP, DCHP and DEHA contents in MSS and foreign salt (FS). Na ion was shown a significantly higher level (p<0.05) in FS (407,345.87~426,612.14 ppm) than in MSS (363,633.98 ppm), but it was shown a high level in Mg (p<0.01), K (p<0.05), Ca ion (p<0.05) of FSS compared to foreign refined salt (FRS). Cl ion (532,727.07 ppm) of MSS was the most low level (p<0.001) compared to FS, but it was shown a high level (p<0.001) in Br ion (625.07 ppm). $SO_4$ ion was not shown a significant difference in DS and FS. It was display a high level in Mn of MSS, and Al, Fe of FLSS. Heavy metal contents (As, Cd, Pb and Hg) in MSS and FS was not significant difference, it was safety level as edible salt.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.418-429
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• 2011

Novel chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), and zirconyl(II) complexes of $N^1,N^2$-bis(3-((3-hydroxynaphthalen-2-yl)methylene-amino)propyl)phthalamide ($H_4L$, 1) have been synthesized and characterized by elemental, physical, and spectral analyses. The spectral data showed that the ligand behaves as either neutral tridentate ligand as in complexes 2-5 with the general formula $[H_4LMX_2(H_2O)]{\cdot}nH_2O$ (M=Cu(II), Ni(II), Co(II), X = Cl or $NO_3$), neutral hexadentate ligand as in complexes 10-12 with the general formula $[H_4LM_2Cl_6]{\cdot}nH_2O$ (M=Fe(III), Cr(III) or Ru(III)), or dibasic hexadentate ligand as in complexes 6-9 with the general formula $[H_2LM_2Cl_2(H_2O)_4]{\cdot}nH_2O$ (M = Cu(II), Ni(II), Co(II) or Mn(II), and 13 with general formula $[H_4L(ZrO)_2Cl_2]{\cdot}8H_2O$. Molar conductance in DMF solution indicated the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complexes 2, 5, and 6 showed $g_{\parallel}$ >g> $g_e$, indicating distorted octahedral structure and the presence of the unpaired electron in the $N^1,N^2$ orbital with significant covalent bond character. For the dimeric copper(II) complex $[H_2LCu_2Cl_2(H_2O)_4]{\cdot}3H_2O$ (6), the distance between the two copper centers was calculated using field zero splitting parameter for the parallel component that was estimated from the ESR spectrum. The antibacterial and antifungal activities of the compounds showed that, some of metal complexes exhibited a greater inhibitory effect than standard drug as tetracycline (bacteria) and Amphotricene B (fungi).

• Journal of the Korean Chemical Society
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• v.60 no.6
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• pp.402-409
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• 2016

Thin films of lead sulfide colloidal quantum dots (CQDs) of 2.8 nm in diameter are fabricated and their surfaces are passivated by 3-mercaptopropionic acid (MPA) ligand or hybrid type ($MPA+CdCl_2$) ligand, respectively. The changes in valence band electronic structure and atomic composition of each PbS CQD film upon post-treatment such as air, N2 annealing or UV/Ozone have been studied by photoelectron spectroscopy. The air annealing makes the CQD fermi level to move toward the valence band leading to "p-type doping" regardless of ligand type. The UV/Ozone post-treatment generates $Pb(OH)_2$, $PbSO_x$ and PbO on both CQD surfaces. But the amount of the PbO has been reduced in hybrid type ligand case, especially. That is probably because the extra Pb cations in (111) surface are additionally passivated by $Cl_2$ ligand, which limits the reaction between the Pb cation and ozone.