• 제목/요약/키워드: Vacuum Adsorption

검색결과 301건 처리시간 0.046초

Adsorption of p-Nitrophenol by Surface Modified Carbons from Aqueous Solution

  • Goyal, Meenakshi
    • Carbon letters
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    • 제5권2호
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    • pp.55-61
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    • 2004

  • Adsorption isotherms of p-nitrophenol from its aqueous solutions on two samples of activated carbon fibres and two samples of granulated activated carbons have been determined in the concentration range 40~800 mg/L (ppm). The surface of these carbons was modified by oxidation with nitric acid and oxygen gas, and by degassing the carbon surface under vacuum at temperatures of $400^{\circ}C$, $650^{\circ}C$ and $950^{\circ}C$. The oxidation of carbon enhances the amount of carbon-oxygen surface groups, while degassing decreases the amount of these surface groups. The adsorption of p-nitrophenol does not depend upon the surface area alone but appears to be influenced by the presence of oxygen groups on the carbon surface. The adsorption decreases on oxidation while the degassing of the carbon surface enhances the adsorption. The decrease in adsorption depends upon the strength of the oxidative treatment being much larger in case of the oxidation with nitric acid, while the decrease in adsorption on degassing depends upon the temperature of degassing. The results show that while the presence of acidic surface groups which are evolved as $CO_2$ on degassing suppress the adsorption of p-nitrophenol, the presence of non acidic surface groups which are evolved as CO on degassing tend to enhance the adsorption. Suitable mechanisms compatible with the results have been presented.

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산소 흡착에 의한 텅스텐 결정면의 일함수 변화 (Work Function Change Induced by Oxygen Adsorption on Tungsten Single Crystal Surfaces)

  • 박노길;김기석;황정남;최대선
    • 한국진공학회지
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    • 제2권3호
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    • pp.319-324
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    • 1993

  • 개끗한 텅스텐 결정면의 일함수와 산소 흡착에 의한 텅스텐 결정면(123), (310), (221)의 일함수의 변화를 장전자 방출법으로 측정하였다. 일함수는 Fowler Nordheim equation을 사용하여 계산하였으며 흡착율을 결정할 수 있는 간단한 방법을 제시하였다.

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Adsorption of Cysteine on Ge(100)

  • 이한길;윤영상;신나리;박선민;양세나;황한나;황찬국;김세훈
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2009년도 제37회 하계학술대회 초록집
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    • pp.320-320
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    • 2009

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