Immobilization Reaction of Chromate Ion Using Ca4Al2(OH)12·Cl2·4H2O

Junichi Ohya; Hiroyuki Sango; Etsuo Sakai

doi:10.4028/www.scientific.net/KEM.617.24

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HomeKey Engineering MaterialsKey Engineering Materials Vol. 617Immobilization Reaction of Chromate Ion Using...

Immobilization Reaction of Chromate Ion Using Ca₄Al₂(OH)₁₂·Cl₂·4H₂O

Abstract:

Hydrocalmite-like hydrate is one of calcium aluminate hydrated products. This hydrate has a layer structure and the principal layer, which is similar to calcium hydroxide define alternate with interlayer including divalent anions and water molecules. Their anions are able to react with outer anions by anion-exchange reaction. In this study, anion-exchange reaction between hydrocalmite-like hydrate including chloride anion (Ca₄Al₂(OH)₁₂·Cl₂·4H₂O, Cl-HC) and chromate anion (CrO₄^2-) is examined. CrO₄^2- is immobilized in various hydrated forms, which are varied with an increasing in the additive ratio of CaCrO₄ to Cl-HC. As the additive ratio of CaCrO₄ to Cl-HC is below 1.0 in molar, Ca₄Al₂(OH)₁₂·CrO₄·nH₂O (n=6 or 8, CrO₄-HC) is formed. In this case, the concentration of chromate ion in solution is less than 1.0 ×10^-3 mol·dm^-3 and over 99% of chromium immobilize in solid phase. However, when the additive ratio of CaCrO₄ is over 1.0, ettringite type hydrate including CrO₄^2- (Ca₆Al₂(OH)₁₂·3CrO₄·26H₂O) is generated and over 10 % of chromium is eluted from the solid phase.

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Periodical:

Key Engineering Materials (Volume 617)

Pages:

24-27

DOI:

https://doi.org/10.4028/www.scientific.net/KEM.617.24

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Online since:

June 2014

Authors:

Junichi Ohya*, Hiroyuki Sango, Etsuo Sakai

Keywords:

Anion Exchange, Calcium Aluminate Hydrated Products, Chromate Ion, Hydrocalmite-Like Hydrates

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