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 Y3+ from aqueous solution

Abstract

CO32−-intercalated Cu–Al layered double hydroxide (CO3·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 CO3·Cu–Al LDH occurred in four stages. The production of Cu–Al oxide was caused by the thermal decomposition of CO3·Cu–Al LDH until the third stage. The first stage was the elimination of adsorbed surface water and interlayer water in CO3·Cu–Al LDH. The second and third stages were the dehydroxylation of the brucite-like octahedral layers and the elimination of CO32− intercalated in the interlayers. The edta·Cu–Al LDH was found to take up Y3+ in aqueous solution. The uptake of Y3+ was caused not only by the chelating function of Hedta3− 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 Sc3+>Y3+>La3+ for all time durations, which was attributable to differences among the stabilities of Sc(edta)−, Y(edta)− and La(edta)−.