Properties of Hexacyanocobaltate(III)-Exchanged Hydrotalcite-Like Minerals

Eiichi Suzuki, Satoshi Idemura and Yoshio Ono
Department of Chemical Engineering, Tokyo Institute of Technology Ookayama, Meguro-ku, Tokyo 152, Japan

Abstract: Hydrotalcite-like minerals, containing Mg2+-Al3+-Xn- (Xn- = NO3-, Cl-, SO42-, or CrO42-), Zn2+-Al3+-NO3-, or Zn2+-Cr3+-NO3- ions, were intercalated with Co(CN)63- by an anion exchange method. For most of the minerals examined, the degree of anion exchange was 79–90%. X-ray powder diffraction patterns of the ion-exchanged samples revealed two peaks at about 8° and 11°2θ (CuKα radiation) attributable to reflections from expanded and non-expanded interlayers, respectively. The intensity of the peak at about 8°2θ was a linear function of the degree of anion exchange. The amount of hexane adsorbed onto the anion-exchanged sample increased linearly with the increase in degree of anion exchange. From these results, anions near the edge of the interlayers appear to have been preferentially replaced by Co(CN)63- at a low degree of anion exchange, whereas those at some distance from the edge were replaced only at a high degree of anion exchange. The adsorption capacity of the Co(CN)63--exchanged sample for hydrocarbons was: hexane ≃ 2-methylpentane ≫ cyclohexane > methylcyclohexane. The adsorption of chain hydrocarbons and cyclic hydrocarbons was different.

Key Words: Adsorption • Anion exchange • Hexacyanocobaltate • Hydrocarbons • Hydrotalcite • Intercalation

Clays and Clay Minerals; April 1989 v. 37; no. 2; p. 173-178; DOI: 10.1346/CCMN.1989.0370209
© 1989, The Clay Minerals Society
Clay Minerals Society (www.clays.org)