• 한국환경과학회지
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• 제5권6호
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• pp.739-748
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• 1996

This study was carried out to investigate the chemical characteristics ol rainwater sampled in Cheju City from July 1994 to June 1996. Concentrations of major ions (Cl-,$SO_4^{2-}$, NO_3^-$, $Na^+$, $K^+$, Ca^{2+}$, $Mg^{2+}$ and NH_4^+$) were determined. The pH of rainwater, calculated from the volume weighted H+ concentration, was found to be 5.61, indicating extensive neutralization of the acidity in the rain. The relative magnitude of average ionic concentrations followed the relation Cl-> $SO_4^{2-}$) $Na^+$> Ca^{2+}$> NH_4^+$> NO_3^-$> $Mg^{2+}$> $K^+$. The ions associated with sea salt, namely $Na^+$ and $Cl^-$, dominated the total concentration of ions in the rainwater and the $SO_4^{2-}$ ion accounts for 20% of total concentration. [H+][nss-SO42-+NO3] ratio and a multiple regression for $SO_4^{2-}$ and NO3- ions against $H^+$, $Ca^{2+}$ and $NH_4^+$ suggested that all of $SO_4^{2-}$ and $NO_3^-$ in rainwater was not necessarily associated with $H_2SO_4$ and $HNO_3$, but might also occur in combination with $NH_4^+$ or Ca^{2+}$. The monthly mean concentrations of $SO_4^{2-}$-, Ca^{2+}$ and $NH_4^+$ in spring time was higher than those in other seasons. These results may De attributed to the fertilizer application as the local sources and the yellow sand phenomina as a regional-scale sources.

• 한국환경보건학회지
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• 제30권2호
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• pp.161-166
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• 2004

The impact of dissolved wastewater constituents on the treatment of synthetic bisphenol A (BPA) solutions was investigated under a variety of reaction conditions. The laccase enzyme from Trametes vesicolor was used for the BPA treatment. The constituents studied included various inorganic salts, organic compounds and heavy metal ions. BPA degradation was inhibited by sulfate, thiosulfate, sulfide, nitrite, and cyanide ions at 25 mg/$\ell$, 100mg/$\ell$, 25 mg/$\ell$ 150 mg/$\ell$, and 2.5 mg/$\ell$, respectively. However, the inhibitive effects of sulfide and sulfite on BPA degradation were diminished by additional aeration to oxidize them. Formaldehyde significantly reduced the rate of BPA degradation at 1.0% among organic compounds studied. Among heavy metal ions tested, Fe(II) substantially suppressed BPA removal at 1 mM. MgCl$_2$ and CaCl$_2$ exhibited great inhibition of BPA degradation at 25mM.

• Nuclear Engineering and Technology
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• 제7권1호
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• pp.25-29
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• 1975

1-Phenethyl Chloride와 2-Phenethyl Chloride의 할로겐 교환반응 속도를 아세톤 용매속에서 방사성 할라이드 이온을 사용하여 측정하였으며, 활성화 엔탈피와 활성화 엔트로피를 결정하였다. 이 반응은 S$_{N}$2 반응이며 할라이드 이온의 상대적 친핵성의 순서는 Cl->Br->I-이고 반응 속도는 Benzyl Chloride와 비교해 볼때 대체적으로 느리다. 이 결과를 할라이드 이온의 용매화 효과와 HSAB원리로 설명하였다.

• Bulletin of the Korean Chemical Society
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• 제21권8호
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• pp.785-792
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• 2000

Mass spectral fragmentations of six chlorinated organophosphorus pesticides were investigated using electron impact mass spectrometry. Understanding the fragmentation pathways, based on the fragment ions of mass spectra, should be useful in the structural elucidation and chemical identification of these compounds. The pro-posed fragmentation pathways were verified by collision-induced dissociation B/E-linked scan spectra. ln most cases,the structures of characteristic fragment ions could be expected by the observation of the peak clusters due to 35Cl and 37Cl isotopes. According to substituted groups on phosphorus atom, phosphate and phospho-rothioate exhibited significantIy differentfragmentation patterns. Especially, phosphate and phosphorothioate with diethyl ester produced more diverse fragment ions than that with dimethyl ester.

• Corrosion Science and Technology
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• 제18권2호
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• pp.49-54
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• 2019

The purpose of this paper is to present failure analysis, of the heat exchanger tube in a district heating system. SS304 stainless steel is used, as material for the heat exchanger tube. The heat exchanger operates in a soft water environment containing a small amount of chloride ions, and regularly repeats operation and standstill period. This causes concentration of chloride ions on the outer surface of the tube, as well as repeat of thermal expansion, and shrinkage of the tube. As a result of microscopic examination, cracks showed transgranular as well as branched propagation, and many pits were present, at the initiation point of each crack. Energy disperstive spectroscopy analysis showed Fe and O peak, as well as Cl peak, meaning that cracks were affected by Cl ion. Failure of the tube was caused by chloride-induced stress corrosion cracking by thermal stress, high temperature, and localized enrichment of chloride ions.

• 방사성폐기물학회지
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• 제15권4호
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• pp.313-320
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• 2017

LiCl-KCl 용융염에서 광학적으로 투명한 텅스텐 망으로 제작된 작업전극에 대해 사마륨의 전기화학적 거동을 Cyclic voltammetry와 Potential step chronoabsorptometry의 전기화학적 및 분광전기화학적 방법으로 조사하였다. Cyclic voltammogram으로 결정된 $Sm^{3+}/Sm^{2+}$의 산화환원 반응의 가역성을 기반으로 형식전위와 확산계수를 계산하여 각각 -1.99 V vs. $Cl_2/Cl^-$와 $2.53{\times}10^{-6}cm^2{\cdot}s^{-1}$를 얻었다. 작업 전극에 -1.5 V vs. Ag/AgCl (wt%)로 전압을 인가하여 측정한 Chronoabsorptometry를 통해 사마륨 이온의 특성 파장으로 $Sm^{3+}$에 대해 408.08 nm, $Sm^{2+}$에 대해 545.62 nm를 확인하였다. Voltammogram에서 얻은 환원 피크 전압과 산화 피크 전압을 이용하여 Potential step chronoabsorptometry를 수행하였다. 545.63 nm의 흡광피크 값을 분석하여 $2.15{\times}10^{-6}cm^2{\cdot}s^{-1}$의 확산계수를 얻었으며 이 값은 동일한 온도에서 Cyclic voltammtry 분석으로 얻은 값과 큰 차이를 보이지 않았다. 실험결과로부터 고온 용융염에서 광학적으로 투명한 작업전극을 이용한 분광전기화학적 방법이 용융염에 용해된 이온의 종류를 확인하며 전기화학적 거동을 조사하는데 유용한 도구로 활용될 수 있음을 확인하였다.

• 한국세라믹학회지
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• 제23권4호
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• pp.62-68
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• 1986

$(Pb_{1-x} La_x)(Zr_{0.65} Ti_{0.35})_{1-x/4}O_3$ (PLZT X/65/35) powders were prepared by molten salt synthesis using NaCl-K Cl and conventional calcining of oxides. The effects of molten salt on formation and charactrization of PLZT powder and on dielectric piezolectric and optical properties of PLZT ceramics were studied, The completed PLZT powder formation in the presence of fused salt was attained at 50-10$0^{\circ}C$ lower temperature than that in solid state reaction and the particle size of the powder made by molten salt synthesis was markedly increased with increasing calcining temperature. The substitution of Na and/or K ions in NaCl-KCl for Pb ion in process of molten salt synthesis was increased with increasing La concentration Z. These substituted Na and/or K ions were identified as the origins of decreasing coupl-ing factor and optical transmittance of PLZT ceramics.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.927-931
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• 2021

In this work, an attempt is made to improve the electrochemical corrosion resistance of Zircaloy-4 by helium ions implantation. For this purpose, the Zircaloy-4 was implanted with 300 keV helium ions of fluences 1 × 10¹³, 1 × 10¹⁵, and 1 × 10¹⁶ ions-cm^-2 by using Pelletron Accelerator. Electrochemical tests of pristine and ion-implanted samples were performed in NaCl solution and their potentiodynamic polarization curves were obtained. The results showed enhancement of the corrosion resistance of Zircaloy-4 after helium ions implantation. The corrosion rate and current density of the material were significantly reduced by the helium implantation. The decrease in corrosion parameters was attributed to helium ions diffusion inside Zircaloy-4 that reduced the electrons flow from the samples.

• 융합정보논문지
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• 제12권2호
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• pp.134-141
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• 2022

알루미늄-공기 전지의 성능을 향상시키기 위해서는 전극의 전기화학적 특성에 미치는 전해질의 영향을 이해하는 것이 매우 중요하다. 본 연구에서는 NaCl, LiCl, CaCl₂, ZnCl₂와 같이 동일한 음이온을 가지나 양이온이 다른 전해질을 사용하여 음극과 양극에서 진행되는 전기화학적 산화·환원 반응에 미치는 전해질 양이온의 영향에 관하여 조사하였다. 전극의 방전 전위 및 비용량에 전해질 양이온이 영향을 준다는 것이 방전 시험, 주사전자현미경과 X-선 회절 분석에 의해 확인되었다. NaCl과 LiCl 전해질 용액 중에서 상대적으로 높은 셀 전압과 비용량이 얻어졌다. 양극 표면에는 Ca²⁺와 Zn²⁺ 이온에 의해 전극 반응을 방해하는 침전물이 생성되었으며, 이로 인해 양극 성능이 저하되었다. 게다가 Ca²⁺ 이온은 음극의 부동태화를 유발하면서 음극의 성능 저하를 촉진시켰다. 이것은 전해질의 양이온이 양극과 음극의 전기화학적 성능에 각각 다른 영향을 주고 있음을 시사하는 것이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.221-226
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• 2001

Chloride diffusion effect of cement paste, freezing and thawing test, carbonation of concrete specimen were carried out using inorganic coating material. According to the chloride ions diffusion test, it is elucidated that permeability and diffusion coefficient of Cl￣ ions and apparent coefficient of coated cement paste is smaller than plain cement paste. A durability of coated concrete specimen was enhanced by the experiment result of concrete carbonation and freezing thawing test.