Ca-Al exchange selectivity and its effect on acid-extraction of trace cadmium from a smectitic soil

• WADA SHIN-ICHIRO

  Faculty of Agriculture, Kyushu University

• TAKASE MASAAKI

  Faculty of Agriculture, Kyushu University

• MORI YUKI

  Faculty of Agriculture, Kyushu University

Abstract

We carried out Ca-Al exchange equilibrium experiments on a smectitic soil and calculated Gaines-Thomas selectivity coefficient. The natural logarithm of the Gaines-Thomas selectivity coefficient scattered around 4.6 with no noticeable trend. The natural logarithm of the thermodynamic equilibrium constant calculated with the aid of Rothmund-Kornfeld equation was 4.58 at 298 K and 1 atm, indicating that the soil strongly prefers Al³⁺ to Ca²⁺.<BR>On the basis of the measured Al³⁺-selectivity we numerically examined the effect of cation exchange reactions involving A1³⁺ during the acid extraction of Cd from soils. The results of computation showed that more Cd²⁺ is extracted when the extracting acid dissolves soil minerals and releases A1³⁺. This is due to the higher preference of smectite for Al³⁺ than for H⁺.

Journal

• Clay Science

  Clay Science 12 (1), 11-15, 2002

  The Clay Science Society of Japan

Keywords

• Ion exchange selectivity
• Ca-Al exchange
• Gaines-Thomas selectivity coefficient
• Rothmund-Kornfeld equation
• Cadmium
• Smectitic soil

Details

• CRID: 1390282679087824640
• NII Article ID: 110003709236
• NII Book ID: AA00607148
• DOI: 10.11362/jcssjclayscience1960.12.11
• ISSN: 21863555
• ISSN: 00098574
• Text Lang: en
• Data Source:
  • JaLC
  • CiNii Articles
• Abstract License Flag: Disallowed