• Archives of Pharmacal Research
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• 제4권2호
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• pp.109-115
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• 1981

In the present investigation, an attempt has been made to apply the methods of classical chemical kinetics to the hydrolytic reaction of pipethanate hydrochloride. By successively keeping all but one variable essentially constant, it has been possible to resolve the overall effect of the individual contributing factors. Since nearly all commercial pipethanate preparations are formulated with antacid, studies were made at several constant hydrogen ion concentration ranging pH 0.4 to 7.5. Rate measurement was also carried out in temperature ranging from $25^{\circ}C$ to $60^{\circ}C$. The hydrolysis of pipethanate is found to be of first order with respect to pipeethanate concentration over an experimental range of hydrogen ion concentration (pH 0407.5). The apparent activation energy(Ea) at pH 7.5 is 18.30 Kcal/mole and the frequency factor is $1.1408 {\times}10^{9}sec^{-1}$. The rate of the hydrolysis has a minimum at pH 2.5-3.5. In this region the half-life of pipethanate was about15.3 days at $60^{\circ}C$. The catalytic effect of water was found to be $K_{H_2O}$ = $3.16{\times}10^{-5}min^{-1}$ at $60^{\circ}C$. The catalytic constants of the hydroxyl ions and hydrogen ions at $60^{\circ}C$ were also found to be $K_{OH}$ = $4.5519{\times}10^{-5}min^{-1}$ and $K_{H}+$ = $1.1568{\times}10^{-2}min^{-1}$, respectively. This reaction appears to be primarily base catalyzed hydrolysis and pipethanate is relatively reluctant toward acid catalyzed hydrolysis. A positive primary salt effect was noted in the solution of phpethanate at pH 7.5 and at $60^{\circ}C$.

• 센서학회지
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• 제6권2호
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• pp.131-136
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• 1997

The ISFET(ion sensitive field effect transistor), a semiconductor ion sensor, has many advantages over conventional ion sensors. Various single-sensor type ISFET pH-meters have been developed. However, they could not be applied in fields because their performances are directly affected by the sensor condition. With only one sensor, the system could be easily damaged from environmental factors, and reliability of it is decreased. Therefore, a 4-channel PH-meter system is proposed to improve the reliability of ISFET pH-meter. It has 4 ISFETS as ion sensor, and a software which contains a new calibration and measurement algorithm appropriate to the system. The reliability of the system was proved by measuring hydrogen ion concentration in the pH standard solutions and buffer solutions.

• 자원리싸이클링
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• 제10권6호
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• pp.9-14
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• 2001

폐리튬이온전지의 재활용 일환으로 양극활물질인 $LiCoO_2$로부터 Co와 Li을 회수하기 위하여 황산침출거동을 조사하였다. 황산 2M용액, $75^{\circ}C$ 조건에서 환원제를 첨가하지 않은 경우, $LiCoO_2$로부터 Li가 거의 100% 침출되는 반면에 Co는 같은 조건에서 40% 이하의 침출율을 보였다. Co의 침출율을 향상시키기 위하여 과산화수소를 환원제로 2~20 vol%범위에서 사용하였다 10 vol% 이상의 과산화수소를 첨가하였을 때, Co와 L거 침출율은 모두 95% 이상 이었다. 이는 환원제로서 과산화수소가 Co(III)를 Co(II)로 환원시켜 침출이 용이해졌기 때문으로 생각된다. 황산농도, 온도, 과산화수소 첨가량이 증가함에 따라 Co와 L리 침출율은 증가한 반면에 초기 광액농도가 증가할수록 Co와 L긴 침출율은 감소하였다. 이상의 조업변수 실험을 통하여 코발트계 리튬이온전지의 양극활물질인 $LiCoO_2$의 황산침출에서 황산농도 2 M, 침출온도 $75^{\circ}C$,초기광액농도 100 g/L, 과산화수소 첨가량 20 vol%에서 30분의반응시간이 침출 최적조건으로 생각된다.

• 한국대기환경학회지
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• 제24권6호
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• pp.674-681
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• 2008

Silver as a metal catalyst has been used to remove odorous compounds. In this study, silver particles in nano sizes ($5{\sim}30nm$) were prepared on the surface of $NaHCO_3$, the supporting material, using a sputtering method. The silver nano-particles were dispersed by dissolving $Ag-NaHCO_3$ into water, and the dispersed silver nano-particles in the aqueous phase was applied to remove inorganic odor compounds, $NH_3$ and ${H_2}O$, in a scrubbing reactor. Since ammonia has high solubility, it was removed from the gas phase even by spraying water in the scrubber. However, the concentration of nitrate (${NO_3}^-$) ion increased only in the silver nano-particle solution, implying that the silver nano-particles oxidized ammonia. Hydrogen sulfide in the gas phase was rapidly removed by the silver nano-particles, and the concentration of sulfate (${SO_4}^{2-}$) ion increased with time due to the oxidation reaction by silver. As a result, the silver nano-particles in the aqueous solution can be successfully applied to remove odorous compounds without adding additional energy sources and producing any harmful byproducts.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.339.1-339.1
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• 2014

In this paper we studied the application of inter-poly dielectric as silicon dioxide-like film was deposited by the higher energy assisting deposition (HEAD) process the modified CCP process, which enables low temperature (LT) process and improving film density. In these experiments the relative hydrogen concentration of $SiO_2$-like films deposited on silicon substrate were analyzed by the secondary ion mass spectroscopy (SIMS) and it was shown that our lower hydrogenated oxide (LHO) film prepared by HEAD process with the precursor contained the siloxane species had lower hydrogen concentration, $8{\times}10{\cdot}^{22}cm{\cdot}^3$ than that of the commercial undoped silicon glass (USG) film ($1{\times}10{\cdot}^{21}cm{\cdot}^3$) prepared by the high density plasma-chemical vapor deposition (HDP-CVD). We consider that the LHO film deposited by HEAD process used as high performance material into Flash memory devices.

• Korean Chemical Engineering Research
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• 제56권3호
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• pp.315-319
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• 2018

고분자전해질연료전지(PEMFC)의 고분자막 전기화학적 내구성을 셀 밖에서 평가하는 방법으로 펜톤(Fenton)반응이 많이 이용된다. 본 연구에서는 펜톤 반응에 영향을 주는 인자를 파악하고자 하였다. 반응진행도를 파악하기 위해 펜톤 반응에서는 생성물로서 라디칼을 분석해야 하는데, 라디칼을 분석하기 어려워 반응물인 과산화수소 농도를 분석해 반응진행도를 측정하였다. 온도에 따른 과산화수소 변화속도를 측정해 활성화 에너지를 계산한 결과 180분에서 24.9 kJ/mol 이었다. 펜톤반응 속도는 철이온 농도에 많은 영향을 받았다. $80^{\circ}C$, 200 rpm, $Fe^{2+}$ 80 ppm 조건에서는 1시간동안에도 과산화수소 농도가 20%이상 처음과 차이가 나므로 용액교체를 자주 하는 것이 막열화 속도를 증가시킴을 보였다.

• 한국대기환경학회지
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• 제32권3호
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• pp.248-255
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• 2016

The leaves of three plant species, such as soybean, raspberry, and kudzu, exposed to hydrogen fluoride was collected in an area surrounding an emission source where the release accident occurred. The ultrasonic-assisted extraction and analysis of fluoride by ion chromatography was carried out. The mean concentration of fluoride in the leaves of three plant species exposed to hydrogen fluoride was $5,409{\pm}1,198mg\;F/kg\;dry\;wt$ and $788{\pm}339mg\;F/kg\;dry\;wt$, respectively. The mean fluoride concentration in ambient air were estimated to be $2.36{\pm}0.65mg/m^3$ ($2.89{\pm}0.79ppm$) and $0.35{\pm}0.15mg/m^3$ ($0.43{\pm}0.19ppm$) in exposed and unexposed sites, respectively. It seems likely that the passive monitoring using plant leaves could identify with respect to plant risk by fluoride in atmosphere.

• 센서학회지
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• 제24권1호
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• pp.6-9
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• 2015

Conventional leak detectors are widely based on helium gas sensors. However, the usage of hydrogen sensors in leak detectors has increased because of the high prices of helium leak detectors and the dearth in the supply of helium gas. In this study, a hydrogen leak detector was developed using solid-state hydrogen sensors. The hydrogen sensors are based on Park-Rapp probes with heterojunctions made by oxygen-ion conducting Yttria-stabilized zirconia and proton-conducting In-doped $CaZrO_3$. The hydrogen sensors were used for determining the potential difference between air and air balanced 5 ppm of $H_2$. Even though the Park-Rapp probe shows an excellent selectivity for hydrogen, the sensitivity of the sensor was low because of the low concentration of hydrogen, and the oxygen on the surface of the sensor. In order to increase the sensitivity of the sensor, the sensors were connected in series by Pt wires to increase the potential difference. The sensors were tested at temperatures ranging from $500-600^{\circ}C$.

• 한국응용과학기술학회지
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• 제29권2호
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• pp.278-285
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• 2012

낮은 농도와 높은 농도의 염 용액에서 Poly(styrene sulfonic acid)(PSSA) 겔의 팽윤도에 대한 이온 특성화 효과를 ${SO_3}^-$와 페닐 고리의 수소결합을 통하여 조사하였다. 낮은 농도에서 PSSA 수화 겔의 수축 정도는 ${SO_3}^-$와 물 사이의 수소 결합에 대한 음이온의 불안정화 영향 때문에 음이온에서는 $SCN^-$<$Br^-$<$Cl^-$<$F^-$의 순서를 따랐다. 재 팽윤은 계에서 특별한 상호 작용이 있을 때 높은 농도에서 관찰되었다. 반면 양이온에서 PSSA 겔의 수축은 $Li^+$<$Na^+$<$K^+$<$Ca^{+2}$ 순서를 따랐다. $Ca^{+2}$ 이온에서의 큰 수축 효과는 이가 양이온(+2)에 의한 PSSA 겔의 물리적 가교 때문에 나타난 것으로 보인다. 양이온에서의 수축은 ${SO_3}^-$와 양이온 사이의 상호작용 정도에 비례하였다. PSSA의 팽윤에 대한 이온 특성화 효과는 ${SO_3}^-$와 페닐 고리의 수화 수소결합에 대한 이온의 영향 정도, 양이온과 ${\pi}$ 전자의 상호작용, 소수성 상호작용, 그리고 분산력 등이 복합적으로 작용하여 나타난다고 볼 수 있다.

• 대한화학회지
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• 제31권3호
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• pp.271-279
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• 1987

Amine기를 가진 Bakelite A와 Ni(II) 사이의 착물을 이용한 ${NO_3}^-$이온 선택성 막전극을 만들었다. 이 막전극은 $H^+$ 이온 및 2가 3가 음이온에는 감응하지 않으며, 특히 이 막전극의 재현성, 감응시간 및 이온선택성등 전기화학적 성질을 조사하여 다른 실용화된 막전극과 비교 고찰하였으며 분석화학에의 응용을 고찰하였다.