• 분석과학
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• 제8권4호
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• pp.793-798
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• 1995

A new chromoionophore sym-(decyl)(2-hydroxy-5-nitrobenzyloxy)-dibenzo-16-crown-5 (1) has been synthesized for $Na^+$ photometry in aqueous media. Apparent $pK_a$ values of 1 in the presence of 0.10 M LiCl, NaCl, and KCl were measured by spectrophotometry in 50% 1,4-dioxane-50% water (v/v) and compared with the $pK_a$ of 8.68 in the presence of 0.10 M TMACl. A significant $pK_a$ shift to a lower pH was only observed for $Na^+$ (${\Delta}pH=1.31$) due to selective binding of 1 with $Na^+$. Based upon this $pK_a$ shift, chromoionophore 1 was found to selectively respond to $Na^+$ with a detection limit of $10^{-3}M$ and no interference from $K^+$ up to 0.05 M for detection of 10.0 mM $Na^+$ in 50% 1,4-dioxane-50% water (v/v).

• 멤브레인
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• 제26권2호
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• pp.152-158
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• 2016

클로알칼리(CA) 멤브레인 셀은 대표적인 염수전해 시스템으로서 가성소다와 염소를 생산하는 염수전기분해 프로세스이다. CA 멤브레인 프로세스는 타 공정에 비해 낮은 에너지 소모량을 가져 CA산업에서 가장 선호되는 공정이다. CA프로세스에 사용되는 과불소계 술폰화 이오노머막은 CA프로세스의 핵심구성 요소이며, 양이온을 선택적으로 이동시키는 역할 및 배리어적인 역할을 제공한다. 하지만, CA 구동을 위해 충족되어야 하는 요소들에 대한 정보가 제한적이기 때문에 알맞은 CA분리막 적용을 위한 제품 간의 연구가 필요하다. 본 연구에서는 실제 셀 구동을 바탕으로 하여 상용 고불소계 분리막의 이온전도경향 및 전기화학적 성능 등을 평가하였다.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.523-529
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• 2023

Cemented uranium tailings backfill created from alkali-activated slag (CUTB) is an effective method of disposing of uranium tailings. Using some environmental functional minerals with ion exchange, adsorption, and solidification abilities as backfill modified materials may improve the leaching resistance of the CUTB. Natural zeolite, which has good ion exchange and adsorption characteristics, is selected as the backfill modified material, and it is added to the backfill materials with cementitious material proportions of 4%, 8%, 12%, and 16% to prepare CUTB mixtures with environmental functional minerals. After the addition of natural zeolite, the uniaxial compressive strength (UCS) of the CUTB decreases, but the leaching resistance of the CUTB increases. When the natural zeolite content is 12%, the UCS reaches the minimum value of 8.95 MPa, and the concentration of uranium in the leaching solution is 0.28-8.07 mg/L, the leaching rate R₄₂ is 9.61×10^-7 cm/d, and cumulative leaching fraction P₄₂ is 8.53×10^-4 cm, which shows that the alkali-activated slag cementitious material has a good curing effect on the CUTB, and the addition of environmental functional minerals helps to further improve the leaching resistance of the CUTB, but it reduces the UCS to an extent.

• 전기화학회지
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• 제11권1호
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• pp.59-63
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• 2008

Poly (vinylchloride) (PVC) membrane electrodes based on neutral carrier, tetracycline was prepared as an active sensor for Hg(II) ion, and tested in different contents of the potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as lipophilic salt. Bis (2-ethylhexyl) sebacate (DOS), bis(l-butylpentyl) adipate (BBPA), 2-nitrophenyl octyl ether (NPOE) and dibutyl phthalate (DBP) were used as diverse plasticizing solvent mediators. This electrode shows excellent potentiometric response characteristics and display good linearity with log $[Hg^{+2}]$ versus EMF response, over a range of concentrations between $10^{-7}$ and $10^{-3}M$. With 30.8mV/decade Nernstian slope, the detection limit was $6.9{\times}10^{-9}M$ and the response time was less than 20s. The proposed electrode yields very good selectivity for mercury (II) ion over many cations such as alkali, alkaline earth, transition and heavy metal ions. And it shows a very stable potential values in a wide pH range. This reliable electrode prepared was kept at least a month without considerable alteration in their response to Hg (II) ion.

• 한국산업융합학회 논문집
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• 제6권3호
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• pp.165-169
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• 2003

To extract alkali metal ions and heavy metal ions, search for crown ether model compounds (4a-b, 5a-b, 6a-b) bearing side arm has led to achieve in 5~6 steps starting from 2,6-dimethylaniline. The determination of structure in their compound derivatives were on the basis of melting point and nuclear magnetic resonance spectroscopy. In the solvent extraction of metal ions from the synthesized derivatives, we observed that silver ion has only high selectivity for synergistic ligation of crown ether.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.453-456
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• 2006

If cement can be manufactured with industrial byproducts such as granulated blast furnace slag(GBFS), phosphogypsum(PG), and waste lime(WL) instead of clinker as its counterproposal, there would be many advantages, including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by CO2 discharge, and reduction of the production cost. This research investigates the chloride ion permeability of NSC concrete added PG and WL to GBFS as sulfate and alkali activators. The result of experiment of chloride ion permeability, showed that NSC is very excellent in seawater resistance. Such a reasons are that the hydrate like CSH gel and ettringite formed dense pore structure of NSC matrix.

• 한국철도학회논문집
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• 제4권2호
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• pp.62-70
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• 2001

Pure copper, Cu-1.1wt%Cd and ACSR(Aluminum Conductor Steel Reinforced) have been used as catenary materials of the electric railway system. Since these materials may be exposed to the corrosive environments like polluted air, acid rain and sea water, it is important to investigate the corrosion rates in various corrosive environments. The aqueous corrosion characteristics of catenary materials in aerated acid, neutral and alkali solutions were studied by using immersion corrosion tests, electrochemical measurements and analytical techniques. In order to examine corrosion characteristics according to the dissolved oxygen content, pH, chloride ion concentration ion, and the addition of Cd to Cu, a series of tests such as potentiodynamic polarization, a.c impedance spectroscopy and galvanic corrosion tests were carried out with these materials. Results showed that the addition of Cd to Cu and chloride ion in the solution have an adverse effects on the resistance to corrosion. Additionally, Galvanic currents between Al and steel wires of ACSR were confirmed by using ZRA(zero resistance ammeter) method.

• 한국건설순환자원학회논문집
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• 제4권2호
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• pp.149-156
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• 2016

이 연구의 목적은 알칼리 활성 슬래그 기반 무시멘트 콘크리트의 염소이온 침투 및 황산염 침투 저항성과 같은 장기 내구성을 평가하는 것이다. 이를 위하여 물-결합재비에 따라 원주형 및 각주형의 무시멘트 콘크리트를 제작한 후, 이들에 대해서 재령 28일부터 365일까지 NT BUILD 492 및 JSTM C 7401 각각에 따라 장기 염소이온 침투 및 황산염 침투 저항성을 평가하였다. 그 결과, 무시멘트 콘크리트의 장기 염소이온 침투 및 황산염 침투 저항성은 물-결합재비에 관계 없이 OPC 콘크리트보다 크게 개선되는 것으로 나타나, 무시멘트 콘크리트의 장기 내구성은 매우 우수한 것으로 입증되었다.

• 대한의용생체공학회:의공학회지
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• 제8권2호
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• pp.123-134
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• 1987

The transport phenomena of alkali metal chlorides through poly(2 hydroxyethyl methacrylate) hydrogel membrane have been studied using electrodialysis. The hydrogel membranes were prepared by the polymerization of 2-hydroxvethyl methacrylate in the presence of 45%(V/V) H2O and ethyleneglycodimethacrylate. The initiator used in the polymerization was azobismethylisobutyrate (AMIB) prepared from azobisiobtyronitrile (AIBN) using Mortimer method. The permeability of alkali metal chlorides such LiCl, NaCl and KCI at 50 voltage was obtained. The permeability of NaCl was also observed at 30, 40, 50, and 60 voltages respectively. The concentration of solutes permeated through the membrane was measurer by flame photometry. The experimental results have been discussed with the comparison of apparent solute molecular size, the self-diffusion coefficient of solutes, the transport number of cations in aqueous solution. These indic aloes that poly(2 hydroxyethyl methacrylate) hydrogel membrane shows a specific selectivity for sodium ion.

• 한국재료학회지
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• 제33권4호
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• pp.135-141
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• 2023

The volatilization of alkali ions in (K,Na)NbO₃ (KNN) ceramics was inhibited by doping them with alkaline earth metal ions. In addition, the grain growth behavior changed significantly as the sintering duration (t_s) increased. At 1,100 ℃, the volatilization of alkali ions in KNN ceramics was more suppressed when doped with alkaline earth metal ions with smaller ionic size. A Ca²⁺-doped KNN specimen with the least alkali ion volatilization exhibited a microstructure in which grain growth was completely suppressed, even under long-term sintering for t_s = 30 h. The grain growth in Sr²⁺-doped and Ba²⁺-doped KNN specimens was suppressed until t_s = 10 h. However, at t_s = 30 h, a heterogeneous microstructure with abnormal grains and small-sized matrix grains was observed. The size and number of abnormal grains and size distribution of matrix grains were considerably different between the Sr²⁺-doped and Ba²⁺-doped specimens. This microstructural diversity in KNN ceramics could be explained in terms of the crystal growth driving force required for two-dimensional nucleation, which was directly related to the number of vacancies in the material.