표면처리 활성탄소섬유에 의한 U(Ⅵ)의 전기흡착 = Electrosorption of U(Ⅵ) on surface modified Activated Carbon Fibers

다국어 초록 (Multilingual Abstract)

The electrosorption of U(VI) from waste water was carried out by using on activated carbon fiber(ACF) electrode in a continuos electrosorption cell. In order to enhance the electrosorption capacity at a lower potential, ACFs was chemically modified in an acidic, basic and neutral solution. Modified ACFs were characterized by the measurement of the functional group and the specific surface area which the adsorption rate and mechanism for the removal of U(VI) can be evaluated.
Specific surface area of all the ACFs decreased in the modified conditions. The amount of the acidic functional groups decrease with the basic and neutral modifications, while the amount increases a lot with the acidic modification when compared to the as-received ACFs. The electrosorption capacity of U(Ⅵ) decreased by using the acid- modified electrode while it was greatly increased by the using neutral and base-modified electrode. The electrosorption amount of U(Ⅵ) on the neutral and base-modified electrode at -0.3 V corresponds to that of the as-received ACFs electrode at -0.9 V.
The electrosorption of U(Ⅵ) could be explained by the solution pH, the stability of the electrolyte and the shielding effect of the surface acidic functional group. The base-modified ACFs increases the solution pH, and U(Ⅵ) was easily precipitated at the surface active site of the ACFs. In the as-received ACFs cell, the NO₃￣ ion as an electrolyte can be reduced to N₂ in a solution at the applied potential of -0.3 V and this would cause the concentration of the electrolyte to be lowered in the electric double layer. This requires a higher potential to obtain the same capacity of the electrosorption. In the acid-modified ACFs, the increased acidic functional group prevents the uranyl ion from an interaction with the charged site, thus showing the shielding effect. From these reasons, the neutral and base-modified ACFs resulted in a higher electrosorption capacity and required a lower applied potential than the as-received ACF.
The electrodesorption efficiency of the ACFs electrode depended on the pH of the electrolyte, it was especially good in a low pH region. Therefore the desorption efficiency of the electrode modified by a neutral solution was better than that of the base solution. It must have been due to the lower pH of the electrolyte.

목차 (Table of Contents)

• 목차
• 1. 서론 = 1
• 2. 이론적 배경 = 4
• 2.1. 흡착 및 흡착평형 이론 = 4
• 2.1.1. 흡착 = 4
• 2.1.2. 흡착평형 = 6
• 2.2. 전기흡착 공정 = 11
• 2.2.1. 전기흡착의 원리 = 11
• 2.2.2. 전기흡착의 특징 = 12
• 2.3. 전기이중층 이론 = 13
• 2.4. 활성탄소섬유의 특징 = 18
• 2.4.1. 활성탄소섬유(ACF) = 18
• 2.4.2. 활성탄소섬유의 구조 = 19
• 2.4.3. 활성탄소섬유의 응용 = 21
• 3. 재료 및 실험방법 = 23
• 3.1. 실험재료 = 23
• 3.2. 활성탄소섬유의 표면처리 = 23
• 3.3. 실험장치 = 24
• 3.4. 실험방법 = 24
• 3.4.1. 활성탄소섬유의 특성 = 24
• 3.4.2. 전기 흡·탈착 실험 = 29
• 3.5. 흡·탈착 농도 및 생성물 분석 = 30
• 4. 결과 및 고찰 = 31
• 4.1. 활성탄소섬유의 구조적 특성 = 31
• 4.2. 활성탄소섬유의 화학적 특성 = 34
• 4.3. 활성탄소섬유의 전기적 특성 = 36
• 4.4. 전기흡착 = 39
• 4.4.1. 전기흡착에 대한 전위의 영향 = 39
• 4.4.2. 전기흡착에 대한 pH의 영향 = 47
• 4.4.3. 전기흡착에 의한 전극의 영향 = 54
• 4.5. 전기탈착 = 56
• 4.6. 생성물 분석과 메커니즘 = 61
• 4.6.1. 생성물 분석 = 61
• 4.6.2. 메커니즘 = 61
• 5. 결론 = 64
• 참고문헌 = 66
• ABSTRACT = 71