Thermal decomposition behavior of Cu-Al layered double hydroxide, and ethylenediaminetetraacetate-intercalated Cu-Al layered double hydroxide reconstructed from Cu-Al oxide for uptake of Y ³⁺ from aqueous solution

CO ₃ ^2--intercalated Cu-Al layered double hydroxide (CO ₃·Cu-Al LDH) was calcined to yield Cu-Al oxide, and then ethylenediaminetetraacetate-intercalated Cu-Al LDH (edta·Cu-Al LDH) was prepared by reconstructing Cu-Al oxide in edta solution. Decomposition of CO ₃·Cu-Al LDH occurred in four stages. The production of Cu-Al oxide was caused by the thermal decomposition of CO ₃·Cu-Al LDH until the third stage. The first stage was the elimination of adsorbed surface water and interlayer water in CO ₃·Cu-Al LDH. The second and third stages were the dehydroxylation of the brucite-like octahedral layers and the elimination of CO ₃ ^2- intercalated in the interlayers. The edta·Cu-Al LDH was found to take up Y ³⁺ in aqueous solution. The uptake of Y ³⁺ 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. The edta·Cu-Al LDH was found to selectively take up rare earth ions from a mixed solution. The degree of uptake was high, in the order Sc ³⁺ > Y ³⁺ > La ³⁺ for all time durations, which was attributable to differences among the stabilities of Sc(edta) ^-, Y(edta) ^- and La(edta) ^-.