• 대한화학회지
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• 제18권6호
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• pp.430-436
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• 1974

여러 pH에서 1,1-dicyano-2-p-dimethylaminophenyl-2-chloroethylene(DPC)의 가수분해 속도상수를 측정하고 넓은 pH 범위에서 잘 맞는 반응 속도로식을 구하였다. 이 식에 의하면 넓은 pH 범위에서 DPC에 대한 가수분해 반응메카니즘을 잘 설명할 수 있다. pH3이하와 7.5이상에서는 속도상수는 hydronium ion과 hydroxide ion 농도에 각각 비례한다. 또 pH 3∼7.5 사이에서는 물, hydronium ion 과 hydroxide ion이 DPC의 가수 분해에 촉매 역활을 함을 알았다.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.230-236
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• 2021

Ionic conduction mechanism of Mg-Al layered double hydroxides (LDHs) intercalated with CO₃^2- (Mg-Al CO₃^2- LDH) was studied. The electromotive force for the water vapor concentration cell using Mg-Al CO₃^2- LDH as electrolyte showed water vapor partial pressure dependence and obeyed the Nernst equation, indicating that the hydroxide ion transport number of Mg-Al CO₃^2- LDH is almost unity. The ionic conductivity of Mg(OH)₂, MgCO₃ and Al₂(CO₃)₃ was also examined. Only Al₂(CO₃)₃ showed high hydroxide ion conductivity of the order of 10^-4 S cm^-1 under 80% relative humidity, suggesting that Al₂(CO₃)₃ is an ion conducting material and related to the generation of carrier by interaction with water. To discuss the ionic conduction mechanism, Mg-Al CO₃^2- LDH having deuterium water as interlayer water (Mg-Al CO₃^2- LDH(D₂O)) was prepared. After the adsorbed water molecules on the surface of Mg-Al CO₃^2- LDH(D₂O) were removed by drying, DC polarization test for dried Mg-Al CO₃^2- LDH(D₂O) was examined. The absorbance attributed to O-D-stretching band for Mg-Al CO₃^2- LDH(D₂O) powder at around the positively charged electrode is larger than that before polarization, indicating that the interlayer in Mg-Al CO₃^2- LDH is a hydroxide ion conduction channel.

• 전기화학회지
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• 제25권2호
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• pp.88-94
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• 2022

알칼리막 연료전지에 사용되는 음이온 교환막은 OH^-을 전달하는 역할을 하며 연료전지의 성능에 많은 영향을 미친다. 따라서 음이온 교환막의 정확한 OH^- 전도도를 측정하는 것은 매우 중요하다. 그러나 OH^-은 대기 중의 CO₂에 의해 중탄산염 형태로 쉽게 피독되어 전해질막의 정확한 OH^- 전도도를 측정하는 것은 매우 어렵다. 본 연구에서는 음이온 교환막의 정확한 OH^- 전도도를 측정하기 위하여 전기화학적 이온교환 처리법을 검증하였다. 또한 CO₂에 노출된 전해질막의 거동을 OH^- 전도도 변화를 통하여 확인하였다. 상용 음이온 교환 막인 Fumatech사의 FAA-3-50과 Orion Polymer사의 Orion TM1와 함께 본 연구 그룹에서 개발한 QPP-6F를 사용하여 정확한 OH^- 전도도 측정 및 CO₂ 피독 효과에 대해서 분석하였다.

• 한국세라믹학회지
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• 제18권2호
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• pp.91-98
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• 1981

Synthetic zeolite A was prerared from domestic Hadong kaolin with sodium hydroxide solution and their ion exchange isotherms of $K^+$, $NH^{4+}$, $Li^+$ and $Ag^+$ ion were presented. The optimum reaction conditions for synthetic zeolite A from calcinated kaolin were 2 fold excess of 2N sodium hydroxide solution, 10$0^{\circ}C$ and 8 hours. It was observed that before the crystallization of zeolite A the samples reacted with sodium hydroxide solution had rather higher ion exchange capacities than zeolite A. The $K^+$-$Na^+$ and $Ag^+$$Na^+$ ion exchange isotherms were signoidal. The initial selectivity series was in the order $Ag^+$$K^+$>$Na^+$>$NH_4$>$Li^+$. Between approximately 33 and 67% replacement of soium ions the selectivity series became $Na^>$ and above 67% became $Ag^+$>$K^+$. Evidence were also presented to demonstrate that 8 out of 12 sodium ions per pseudo unit cell were not easily replaceable by lithium ions and 4 out of 12 not easily replaceable by ammonium ions.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.107-108
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• 2015

Layered Double Hydroxides is known as a hydrotalcite-like material. It is a type of anionic clay with planar structure. It is composed of layer structure which is able to exchange anion between two layers which includes divalent ion and trivalent ion. Therefore, layered double hydroxide is applicable for eliminating harmful heavy metals and anionic substances which exist in the concrete. Because it is also able to be used as catalyst and has high possibility of utilization, It is getting an large amount of attention recently. In this study, an analysis on the structure of the layerd double hydroxide (LDH) which is possible to bind the anion was carried out.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.338-338
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• 2011

The behavior of hydroxide ions on water-ice films was studied by using $Cs^+$ reactive ion scattering (RIS), low energy sputtering (LES) and temperature-programmed desorption (TPD). A $Cs^+$ beam of a low kinetic energy (<100 eV) from $Cs^+$ ion gun was scattered at the film surface, and then $Cs^+$ projectiles pick up the neutral molecules on the surface as $Cs^+$-molecule clusters form (RIS process). In LES process, the preexisting ions on the surface are desorbed by the $Cs^+$ beam impact. The water-ice films made of a thick (>50 BL) $H_2$O layer and a thin $D_2O$ overlayer were controlled in temperatures 90~140K. We prepared hydroxide ions by using Na atoms which proceeded hydrolysis reaction either on the ice film surface or at the interface of the $H_2O$ and $D_2O$ layers.[1] The migration of hydroxide ions from the $H_2O/D_2O$ interface to the top of the film was examined as afunction of time. From this experiment, we show that hydroxide ions tend to reside at the water-ice surface. We also investigated the H/D exchange reactions of $H_2O$ and $D_2O$ molecules mediated by hydroxide ions to reveal the mechanism of migration of hydroxide to the ice surface.

• 대한화학회지
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• 제17권4호
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• pp.269-274
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• 1973

${\alpha}$-Cyano-${\beta}$-Piperonylacrylic Acid의 가분해 속도상수를 자외선분광기를 사용하여 구하였으며 아울러 넓은 pH범위에 잘 맞는 반응속도식도 얻었다. 이 식에 의하면 넓은 pH범위에 잘 맞는 반응속도식도 얻었다. 이 식에 의하면 넓은 pH범위, 특히 종전에 잘 규명된 바 없는 산성용매 속에서의 반응 및 hydroxide ion의 촉매역활 등도 정략적으로 잘 설명할 수 있음을 알았다. 즉 pH4.0이하에서의 가수분해반응은 ${\alpha}$-Cyano-${\beta}$-Piperonylacrylic Acid에 물분자가 첨가되므로써 시작되며 pH $5.0{\sim}7.5$ 에서는 ${\alpha}$-Cyano-${\beta}$-Piperonylacrylic Acid와 ${\alpha}$-Cyano-${\beta}$${\alpha}$-Cyano-${\beta}$-piperonylacrylate anion에 물분자만이 첨가되며 pH 12.0 이상에서는 hydroxide ion만이 ${\alpha}$-Cyano-${\beta}$-piperonylacrylate anion에 첨가됨을 알았다.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.379-390
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• 1998

In endodontic treatment, calcium hydroxide has been used as intracanal medicament. Although calcium hydroxide should be removed thoroughly before permanent root canal filling, no effective method for its removal has been reported. Because of irregularity of root canal walls, root curvatures and anatomic variations, it is insufficient to remove calcium hydroxide from the canal wall only by mechanical instrumentation Considering the chemical effects of irrigants on calcium hydroxide, $Ca^{++}$ dissolving effect from two calcium hydroxide products is investigated, using dis- tilled water, NaOCl, citric acid and EDTA. Vitapex$^{(R)}$ 0.1g and calcium hydroxide 0.03g were dissolved in distilled water, 5% NaOCl, 50% citric acid and 17% EDTA respectively, at 1, 3, 5, 10min. time interval. The solution was filtered using filter paper(pore size $5{\mu}m$) and $Ca^{++}$ concentration was determined by ion chromatography. The result were as follows : 1. Distilled water, NaOCl, citric acid and EDTA abstracted more $Ca^{++}$ from calcium hydroxide than Vitapex$^{(R)}$ except NaOCl 1, 5, 10 time interval. 2. EDTA and citric acid abstracted more $Ca^{++}$ from Vitapex$^{(R)}$ and calcium hydroxide than distilled water or NaOCl. The overall result support the view that water-based calcium hydroxide product is easily removed than oil-based calcium hydroxide product and EDTA, citric acid are more effective in $Ca^{++}$ elution than NaOCl or distilled water.

• 상하수도학회지
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• 제19권4호
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• pp.404-410
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• 2005

A series of batch type adsorption experiments were performed to remove aquatic phosphorus, where the layered double hydroxide (HTAL-CI) was used as an powdered adsorbent. It showed high adsorption capacity (T-P removal: 99.9%) in the range of pH 5.5 to 8.8 in spite of providing low adsorption characteristics (pH<4). The adsorption isotherm was approximated as a modified Langmuir type equation, where the maximum adsorption amount (50.5mg-P/g) was obtained at around 80mg-P/L of phosphorus concentration. A phosphate ion can occupy three adsorption sites with a chloride ion considering the result that 1 mol of phosphate ion adsorbed corresponded to the 3 moles of chloride ion released. Although the chloride ion at less than 1,000mg-CI/L did not significantly affect the adsorption capacity of phosphate, carbonate ion inhibited the adsorption property.

• 대한화학회지
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• 제20권1호
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• pp.73-86
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• 1976

다음과 같은 새로운 4종의 N-(arylsulfonyl)benzamide 유도체와 6종의 N-(arylsulfonyl)benzimidothiophenyl ester 유도체를 합성하였다. m-methyl-N-(arylsulfonyl)benzamide, p-methyl-N-(arylsulfonyl)benzamide, m-nitro-N-(arylsulfonyl)benzamide, p-methoxy-N-(arylsulfonyl)benzamide, p-methyl-N-(arylsulfonyl)benzimidothiophenyl esters, m-methyl-N-(arylsulfonyl)benzimidothiophenyl ester, p-methoxy-N-(arylsulfonyl)benzimidothiophenyl ester, p-nitro-N-(arylsulfonyl)benzimidothiophenyl ester, m-nitro-N-(arylsulfonyl)benzimidothiophenyl ester, p-chloro-N-(arylsulfonyl)benzimidothiophenyl ester. 넓은 pH 범위에서 N-(arylsulfonyl)benzimidothiophenyl esters 유도체의 가수분해속도 상수를 자외선 분광광도법으로 측정하여 넓은 pH 범위에 적용되는 반응속도식을 구하였다. 이 속도식과 치환기효과등으로부터 N-arylsulfonylbenzimidothiophenyl esters 유도체에 대한 가수분해 반응메카니즘을 제안하였다. 즉 pH 11 이상에서는 hydroxide ion이 pH 9 이하에서는 azomethine 기에 물분자가 첨가되므로서 반응이 시작되며 pH 9∼11 사이에서는 물분자와 hydroxide ion이 경쟁적으로 반응함을 알았다.