Uptake of Sc³⁺ and La³⁺ from aqueous solution using ethylenediaminetetraacetate-intercalated Cu-Al layered double hydroxide reconstructed from Cu-Al oxide

A Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta·Cu-Al LDH) was prepared by suspending Cu-Al oxide, obtained by the calcination of CO32 - intercalated Cu-Al LDH, in edta solution. It was found that the reconstruction of Cu-Al oxide to Cu-Al LDH was promoted with an increase in the temperature and time. The reaction in the pH range of around 8 suggests that Hedta^3- was intercalated in the interlayer of Cu-Al LDH. Edta·Cu-Al LDH was found to take up rare metal ions such as Sc³⁺ and La³⁺ in an aqueous solution at a pH of around 6-6.5. The uptake of Sc³⁺ was caused not only by the chelating function of Hedta^3- in the interlayer but also by the chemical behavior of Cu-Al LDH itself. On the other hand, the uptake of La ³⁺ was caused only by the chelating function of Hedta^3- in the interlayer. The Hedta^3- in the interlayer of edta·Cu-Al LDH had the potential to form a chelate complex more preferentially with Sc ³⁺ than with La³⁺.