Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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Microemulsions in Supercritical Carbon Dioxide Utilizing Nonionic Surfactants

초임계 이산화탄소내 비이온성 계면활성제를 이용한 마이크로에멀젼 형성연구

  • Koh, Moonsung (Green Nuclear Research Laboratory, Kyung Hee University) ;
  • Yoo, Jaeryong (Green Nuclear Research Laboratory, Kyung Hee University) ;
  • Park, Kwangheon (Green Nuclear Research Laboratory, Kyung Hee University) ;
  • Kim, Hongdoo (Green Nuclear Research Laboratory, Kyung Hee University) ;
  • Kim, Hakwon (Green Nuclear Research Laboratory, Kyung Hee University)
  • 고문성 (경희대학교 청정제염 연구실) ;
  • 유재룡 (경희대학교 청정제염 연구실) ;
  • 박광헌 (경희대학교 청정제염 연구실) ;
  • 김홍두 (경희대학교 청정제염 연구실) ;
  • 김학원 (경희대학교 청정제염 연구실)
  • Received : 2003.09.13
  • Accepted : 2003.10.30
  • Published : 2004.12.01
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Abstract

Ethoxylated Nonyl Phenol Series (NP-series), nonionic surfactants, were applied for forming microemulsions in supercritical $CO_2$. Measurement results of the solubility in supercritical $CO_2$ are in the following; NP-series were high soluble in carbon dioxide in spite of the fact that those were not $CO_2$-philic surfactants traditionally well known. Water in $CO_2$ microemulsions were also formed stably. A complexation of hydrophilic lengths for $CO_2$-philic parts of NP-Series surfactants was optimized by NP-4 surfactant(N=4) for forming the microemulsions through the experiments. Formation of microemulsions was confirmed by measuring the UV-Visible spectrum through a spectroscopic method and existence of water in the microemulsions was confirmed as well. In order to apply it for a metal surface treatment or electroplating, an experiment for forming acid(organic, inorganic) solution in $CO_2$ microemulsions was carried out. Ionic surfactant in the reaction to an acid solution became unstable to form microemulsions, however, nonionic surfactant was formed stably in the reaction. Results of the study will be utilized for expanding the application scope of supercritical $CO_2$ which is an environmental-friendly solvent.

비이온성 계면활성제인 Ethoxylated Nonyl Phenol 계열(NP-Series)을 초임계 이산화탄소내 마이크로에멀젼 형성 연구에 적용하였다. 초임계 이산화탄소내 용해도 측정결과, 기존에 잘 알려진 친이산화탄소성 계면활성제가 아님에도 안정적인 용해도를 나타내었고, 물과의 마이크로에멀젼 형성에 있어서도 안정적으로 형성되었다. 마이크로에멀젼 형성을 위한 NP-시리즈 계면활성제의 친이산화탄소성기에 대한 친수성기의 길이 배합을 실험을 통해 NP-4 계면활성제(N=4)로 최적화하였다. 마이크로에멀젼 형성을 분광학적 방법인 UV-Visible 스펙트럼을 측정하여 확인하고, 마이크로에멀젼내 물의 존재성도 확인하였다. 금속표면처리나 도금의 적용을 위해 산성용액과 마이크로에멀젼 형성을 실험한 결과, 이온성 계면활성제는 산성용액과의 반응에서 마이크로에멀젼 형성이 불안정해지는 반면, 비이온성 계면활성제는 안정적으로 형성되었다. 본 연구결과는 친환경적 용매인 이산화탄소의 응용분야를 보다 넓힐 수 있을 것이다.

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