電氣化學的 가스센서를 利用한 高分子膜의 가스 透過特性 測定 硏究 = (A) Study on the Measurement of Gas Permeability Characteristics of Polymeric Membrane in Electrochemical Gas Sensor

다국어 초록 (Multilingual Abstract)

The permeability of polymeric membrane was measured against three different gases by means of electrochemical sensor method and one dimensional diffusion model. The electrochemical sensor method and its one dimensional model were proven to be very efficient and fast method for evaluation of gas permeation characteristics, as long as the oxygen is present in the electrolyte, whose concentration reaches zero on the cathode surface during the overall electrochemical reaction. The electrochemical cell for NO₂ was constructed with PTFE (Polytetrafluoroethylene) membrane of Nitto, inc. (51㎛ thickness, pore size of 0.3㎛), which protects internal filling electrolyte solution and supports paste used as electrode. The working electrode was prepared directly on the surface of membrane by Au sputtering, and the counter and reference electrode were graphite coated silver wire. To coat graphite evenly on the silver wire, the equivalent amount of binder was mixed with graphite before coating and heat treatment and drying. The electrolyte was 0.5M HNO₃, and the electrode potential was +0.70V(±0.05). The membrane of the prepared cell was PTFE, and its permeabilities for oxygen, nitrogen dioxide and sulfur dioxide were 11.87 barrer, 5.55 barrer, 2.78 barrer separately. And the temperature dependency of permeability was measured to evaluate activation energy for gas permeation. The activation energy of PTFE for oxygen, nitrogen dioxide and sulfur dioxide were evaluated as 21.03 KJ/mol, 16.09 KJ/mol, and 9.22 KJ/mol, respectively. The present method of electrochemical one dimensional model can be extended to the estimation of the permeability of poisonous gases such as NO₂, SO₂, CO and H₂S for fast and simple application to industrial safety and process control.

목차 (Table of Contents)

• 목차 = ⅰ
• List of Figures = ⅲ
• List of Tables = ⅴ
• Nomenclature = ⅵ
• Ⅰ. 서론 = 1
• Ⅱ. 이론적 배경 = 5
• 2.1 전기화학적 정전위전해식 가스센서 = 5
• 2.1.1 정전위전해식 센서의 작동 원리 = 5
• 2.1.2 Nernst equation = 7
• 2.1.3 Kohlrausch's law and Ostwald's dilution law = 9
• 2.1.4 정전위전해식 센서의 구성 및 반응 = 11
• 2.1.4.1 산소센서의 반응 = 14
• 2.1.4.2 NO₂센서의 전극반응 = 15
• 2.1.4.3 SO₂센서의 전극반응 = 16
• 2.1.5 산화환원 전위 = 17
• 2.2 전극의 투과현상 = 18
• 2.2.1 일차원적 모델링 = 18
• 2.2.2 센서별 가스 투과도 계산 = 20
• 2.2.3 투과도 온도 의존성 = 24
• Ⅲ. 실험방법 = 25
• 3.1 계측시스템의 구성과 제어 = 25
• 3.2 가스별 센서 제작 = 31
• 3.2.1 산소센서 제작 = 31
• 3.2.2 정전위전해식 NO₂ 센서 제작 = 31
• 3.2.3 정전위전해식 SO₂ 센서 선정 = 31
• 3.3 센서별 투과도 측정 및 활성화 에너지 측정 = 33
• Ⅳ. 실험결과 및 고찰 = 34
• 4.1 가스별 센서 제작 = 34
• 4.1.1 산소센서 제작 = 34
• 4.1.2 선정된 정전위전해식 SO₂센서 = 34
• 4.1.3 정전위전해식 NO₂센서 제작 = 37
• 4.1.3.1 전극 제작 = 37
• 4.1.3.2 전해액 개발 = 43
• 4.1.3.3 산화환원 전위선정 = 43
• 4.2 투과현상의 해석 = 46
• 4.2.1 산소센서의 투과도 및 활성화에너지 측정 = 46
• 4.2.2 NO₂와 SO₂센서의 투과도 측정 = 50
• Ⅴ. 결론 = 60
• Ⅵ. 참고문헌 = 62
• ABSTRACT = 70