산처리한 γ-알루미나의 표면 산량과 표면 전하밀도

홍영호; 이창우; 함영민

Journal of the Korean Industrial and Engineering Chemistry, Vol.9, No.3, 377-382, June, 1998

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산처리한 γ-알루미나의 표면 산량과 표면 전하밀도

A Study on the Surface Acid Amount and Surface Charge Density of Acid Treated γ-Alumina

홍영호, 이창우, 함영민

초록

본 연구는 낮은 활성으로 활용성이 제한된 γ-알루미나의 이용을 높이기 위하여 표면을 처리한 알루미나의 계면전기적 특성과 표면활성간의 상관성을 규명하기 위하여 수행되었다. 질산알루미늄을 출발 물질로 하고 암모니아수를 침전제로 사용하여 제조한 알루미나와 황산, 질산, 염산으로 표면 처리한 알루미나를 질량이동법과 site-binding theory를 이용하여 영점전하점을 측정하였다. Amine Titration법과 Hammett 지시약법으로 표면활성점을 구하였다. 전해질에 분산된 알루미나의 계면특성은 전위차적정방법에 의하여 측정된 표면 전하밀도값을 이용하여 분석하였다. 표면전하밀도와 산량의 결과를 이용하여 얻은 γ-알루미나의 표면특성과 계면전기적 특성의 상관성은 다음과 같다. 표면을 처리하지 않은 알루미나는 H_O +9.3인 조건에서 소성온도가 증가함에 따라 산도는 감소한다. 표면처리한 알루미나는 표면을 처리하는 데 사용한 음이온의 농도가 증가하면 표면 이온화상수와 영점전하점은 감소한다. 표면을 처리한 알루미나의 표면전하밀도와 산량은 H_O +4.8인 조건에서 다음과 같은 상관관계를 갖는다.
SO₄^2-/Al₂O₃ : Q_A = -0.172ln(0.0418σ+1.448)
NO₃^-/Al₂O₃ : Q_A = -0.024σ-0.0189
Cl^-/Al₂O₃ : Q_A = -0.01σ-0.2006

This study was carried out to investigate the relation between surface acidity and interfacial electrical characteristics of surface-treated γ-alumina whose surface activity was increased. The points of zero charge (P. Z. C.) of γ-alumina whose surface is treated with the sulfuric, nitric and hydro-chloric acid of various concentration were measured from the site-binding theory and mass transport method. The surface active sites were measured by amine titration method and Hammett indicator method. The interfacial properties at alumina/KCl_(aq) interface were measured by potentiometric titration. From the experimental results, the following results were obtained. Pure γ-alumina surface acidity decreases with the increase of calcination temperature at strength H_O +4.8 as follows.
SO₄^2-/Al₂O₃ : Q_A = -0.172ln(0.0418σ+1.448)
NO₃^-/Al₂O₃ : Q_A = -0.024σ-0.0189
Cl^-/Al₂O₃ : Q_A = -0.01σ-0.2006

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[1] Hong YH, Ham YM, Jang YH, J. Korean Ceram. Soc., 30, 933 (1993)

[2] Sprycha R, J. Colloid Interface Sci., 123, 1 (1989)

[3] Synder RL, Condrate RA, Johnson PF, "Advanced in Materials Characterization," p. 189, Plenum Press, New York (1984)

[4] Tanabe K, "Acid-Base Catalysis," Kodansha (1988)

[5] Hart DD, "Alumina Chemicals Science and Technology Handbook," p. 41, American Ceramic Society, Inc. (1990)

[6] 전학제, "촉매개론," 한림원 (1992)

[7] Atkinson RJ, Posner AM, Quirk JP, J. Phys. Chem., 71, 550 (1967)

[8] Williams RA, "Colloid and Surface Engineering Application in the Process Industries," p. 14 Butterworth-Heinemann Ltd, London (1992)

[9] Hunter RJ, "Zeta Potential in Colloid Science," Academic Press, New York (1981)

[10] Tanabe K, "Solid Acids andBases," Kodansha Scientific Books, Tokyo (1970)

[11] Chapra SC, Canale RP, "Numerical Methods for Engineers," 2nd ed., McGraw-Hill, New York (1988)

[12] Mieth JA, Schwarz JA, Huang YT, Fung SC, J. Catal., 122, 202 (1990)

[13] Janssen MJC, Stein HN, J. Colloid Interface Sci., 111, 112 (1986)