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

산처리한 γ-알루미나의 표면 산량과 표면 전하밀도

  • 홍영호 (혜전전문대학 공업화학과) ;
  • 이창우 (단국대학교 공과대학 화학공학과) ;
  • 함영민 (단국대학교 공과대학 화학공학과)
  • Received : 1998.01.05
  • Accepted : 1998.03.07
  • Published : 1998.06.10

Abstract

This study was carried out to investigate the relation between surface acidity and interfacial electrical characteristics of surface-treated ${\gamma}-alumina$ whose surface activity was increased. The points of zero charge (P. Z. C.) of ${\gamma}-alumina$ 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 ${\gamma}-alumina$ surface acidity decreases with the increase of calcination temperature at strength $H_o{\leq}+9.3$ Surface-treated alumina acidic properties increase with the anion loading on alumina surface. The surface ionization constants decrease with anion loading on alumina surface, then P. Z. C. decreases with acid amount on alumina surface. Acid amount of surface treated alumina can be correlated with surface charge density at strength $H_o{\leq}+4.8$ as follows. $SO_4^2-/Al_2O_3:Q_A=-0.172ln(0.0418{\sigma}+1.448)$ $NO_3^-/Al_2O_3:Q_A=-0.024{\sigma}-0.0189$ $Cl^-/Al_2O_3:Q_A=-0.01{\sigma}-0.2006$.

Keywords

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