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 Hedta3− 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 Hedta3− in the interlayer but also by the chemical behavior of Cu–Al LDH itself. On the other hand, the uptake of La3+ was caused only by the chelating function of Hedta3− in the interlayer. The Hedta3− in the interlayer of edta·Cu–Al LDH had the potential to form a chelate complex more preferentially with Sc3+ than with La3+.

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