• 센서학회지
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• 제16권1호
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• pp.7-10
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• 2007

A thick film catalytic gas sensors which can be operated at $142^{\circ}C$ in presence of ultra violet-light emitting diode has been developed to measure hydrogen concentration in 0-5 % range. The sensing material as a combustion catalyst consists of $TiO_{2}$ (5 wt%) and Pd/Pt (20 wt%) supported on $Al_{2}O_{3}$ powder and the reference material to compensate the heat capacity of it in a bridge circuit was an catalyst free $Al_{2}O_{3}$ powder. Platinum heater and sensor materials were formed on the alumina plate by screen printing method and heat treatment. The effect of UV radiation in the presence of photo catalyst $TiO_{2}$ on the sensor sensitivity, response and recovery time has been investigated. The reduction of operating temperature from $192^{\circ}C$ to $142^{\circ}C$ for hydrogen gas sensing property in presence of UV radiation is attributed to the hydroxy radical and superoxide which was formed at the surface of $TiO_{2}$ under UV radiation.

• Environmental Engineering Research
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• 제25권4호
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• pp.529-535
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• 2020

The present study investigated the photodegradation of synthetic organic dye; violet-3B, without and with the addition of C-N-codoped TiO₂ catalyst using a visible halogen-lamp as a light source. The catalyst was synthesized by using a peroxo sol-gel method with free-organic solvent. The effects of initial dye concentration, catalyst dosage, and pH solution on the photodegradation of violet-3B were examined. The efficiency of the photodegradation process for violet-3B dye was higher at neutral to less acidic pH. The kinetics reaction rate of photodegradation of violet-3B dye with the addition of C-N-codoped TiO₂ followed pseudo-first order kinetics represented by the Langmuir-Hinshelwood model, and increasing the initial concentration of dyes decreased rate constants of photodegradation. Photodegradation of 5 mg L^-1 violet-3B dye achieved 96% color removal within 240 min of irradiation in the presence of C-N-codoped TiO₂ catalyst, and approximately 44% TOC was removed as a result of the mineralization.

• 청정기술
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• 제15권1호
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• pp.42-46
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• 2009

아세틴 촉매상에서 글리세롤(바이오디젤 제조과정의 부산물)과 염화수소 가스로부터 무용매 상태로 디클로로프로판올(DCP)을 직접 제조하는 반응을 기상-액상 회분식 반응기에서 수행하였다. 이를 위해 균일계 아세틴 촉매로 아세틴 혼합물(acetin mixture)과 트리아세틴을 사용하였다. 아세틴 촉매의 활성을 동일한 반응조건($110^{\circ}C$, 3 bar, 3시간)에서 수행된 무촉매 상태에서의 반응성과 비교하였다. 무촉매 반응에 비해 아세틴촉매를 사용한 반응에서 글리세롤의 전환율은 3%정도 증가하였으며 디클로로프로판올의 선택도는 50%가량 증가하였다. 또한 아세틴 혼합물보다는 트리아세틴의 촉매활성이 2% 정도 우수한 것으로 나타났다.

• 자원리싸이클링
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• 제11권2호
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• pp.3-13
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• 2002

본 연구에서는 시안 성분을 제거함에 있어 처리수의 재활용이 가능한 과산화수소에 의한 시안분해 특성을 규명하기 위한 실험을 수행하였다. 수용액중의 과산화수소의 자가분해반응은 pH와 금속촉매(Cu) 유무에 크게 좌우된다. pH 10 이하에서는 자가분해반응은 미미하여 90%이상의 과산화수소가 잔류하지만 pH 12에서는 90경과시 잔류 과산화수소가 9%이하로 낮아졌다. 금속촉매 첨가(5 g Cu/L)한 경우 pH 12에서도 40분 경과후 대부분의 과산화수소가 분해되었다. 유리시안의 휘발성은 용액의 pH에 크게 좌우된다. 동일한 240분 경과시 pH 8이하에서 대부분의 시안이 휘발하는데 반하여 pH 10이상에서는 10%미만이 휘발하였다. 비촉매반응에 의한 과산화수소의 시안분해실험에서는 $H_2$$O_2$/CN 몰비 4까지 과다하게 증가하여도 8%가량의 시안이 잔류하였다. 그러나 구리촉매반응에 의한 과산화수소의 시안분해 실험에서는 과산화수소 및 구리 첨가량이 증가함에 따라 분해속도가 증가하였다. 그러나 일정량 이상 첨가시 과산화수소의 자체분해 반응에 의해 $H_2$$O_2$의 시안분해 효율이 감소하며 과산화수소와 구리의 적정투입량은$ H_2$$O_2$/CN 몰비 2, Cu 몰비 0.05로서 이때의 분해속도는 22 mM/min, $H_2O$$_2$효율은 57%이었다. 또한 이러한 적정조건에서 70분 반응시 완전제거가 가능하였다.

• 대한화학회지
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• 제51권4호
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• pp.346-351
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• 2007

NaHSO4·SiO2를 사용하는 solvent-free 조건하에서 E-geometry를 가진 α,β의 불포화산, α-Cyanoacrylonitriles 와 α-Cyanoacrylates의 효율적인 입체선택적 반응을 수행하였다.

• 한국염색가공학회지
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• 제9권2호
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• pp.41-49
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• 1997

To control free formaldehyde release from fabric finished with N-methylol compounds, resin finished cotton fabric was treated with resorcinol solution, dried and cured. Factors affecting to control formaldehyde release have been investigated. It was shown that the aftertreatment with resorcinol greatly suppressed the free formaldehyde release. Up to concentration of about 5% of resorcinol, the concentration of resorcinol effected on the control of free and evolved formaldehyde. And at high concentration of resorcinol, however, the concentration became rather insensitive to contol formaldehyde release. Addition of some salt catalysts such as ammonium chloride, zinc nitrate, sodium acetate and ammonium acetate, was effective in decreasing formaldehyde release. Considering the effect on the control of formaldehyde and crease recovery, ammonium acetate was concidered to be the best catalyst. It was observed that the optimum curing temperature for the resorcinol treatment was about 15$0^{\circ}C$, and that the curing time did not affected formaldehyde release over three minutes. Although the treatment of resorcinol had a little adverse effect on crease recovery of resin finished fabric, this effect could be negligible.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.289-296
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• 2017

Lysine decarboxylase (CadA) converts ${\small{L}}-lysine$ into cadaverine (1,5-pentanediamine), which is an important platform chemical with many industrial applications. Although there have been many efforts to produce cadaverine through the soluble CadA enzyme or Escherichia coli whole cells overexpressing the CadA enzyme, there have been few reports concerning the immobilization of the CadA enzyme. Here, we have prepared a cross-linked enzyme aggregate (CLEA) of E. coli CadA and performed bioconversion using $CadA^{CLEA}$. $CadA^{free}$ and $CadA^{CLEA}$ were characterized for their enzymatic properties. The optimum temperatures of $CadA^{free}$ and $CadA^{CLEA}$ were $60^{\circ}C$ and $55^{\circ}C$, respectively. The thermostability of $CadA^{CLEA}$ was significantly higher than that of $CadA^{free}$. The optimum pH of both enzymes was 6.0. $CadA^{free}$ could not be recovered after use, whereas $CadA^{CLEA}$ was rapidly recovered and the residual activity was 53% after the $10^{th}$ recycle. These results demonstrate that $CadA^{CLEA}$ can be used as a potential catalyst for efficient production of cadaverine.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.133-134
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• 2013

본 연구는 비전도성 소재 상에 무전해 동도금(Electroless Copper)시 수행되는 씨앗층이나 촉매공정 없이 직접 구리 석출물을 얻는 방법 중 하나에 관한 연구이다. 실리콘 웨이퍼상에 확산방지를 위한 Ta 금속확산방지(Metal barrier)막층 형성 후 무전해 동도금에 침지 후 최소한의 전류를 인가한 결과 균일한 구리피막을 얻을 수 있었으며, 표면 및 단면 조직 분석결과 이를 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3343-3347
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• 2011

A simple efficient and neat synthesis of ${\alpha}$-hydroxy phosphonates has been accomplished from aromatic/heterocyclic aldehydes and diethyl phosphite using $KHSO_4$ as a catalyst under solvent-free conditions at ambient temperature. These compounds are characterized by spectral and analytical data and tested for their anti-oxidant activity.

• KSBB Journal
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• 제4권2호
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• pp.99-103
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• 1989

활엽수의 헤미셀룰로오스를 autohydrolusisgkdu 얻은 용액을 초강 산고체, Nafion을 사용하여 2차 가수분해시키는 반응에 관한 Kinetics를 고찰했다. 연속 column반응기를 사용해 얻을 수 있는 최대 xylose수율은 약 90%이였다. 양이온 물질이 제거된 feed를 사용하면 Nation은 안정된 가수분해 촉매를 사용될 수 있음이 판명되었다.