JSPS Scientist for Joint International Research, School of Chemistry, The University of Melbourne; Associate Professor, Graduate School of Engineering, Tohoku University, Japan.

Speech Title: Layered double hydroxides modified with chelator for the uptake of metal ions from an aqueous solution
Abstract: The development of a scavenger, which has a function of selective uptake of metal ions from an aqueous solution, has been attempted by coupling layered double hydroxide (LDH) with chelator. The edta•Mg-Al LDH, which had an edta anion intercalated in the interlayer of Mg-Al LDH, was found to have a capacity for rapid uptake of Cu²⁺ and Cd²⁺ from an aqueous solution at the constant pH of 5.0. This capacity is attributed to the formation of the edta-metal complex in the interlayer of edta•Mg-Al LDH. The Cu²⁺ was observed to be preferentially taken up from a Cu-Cd mixed chloride solution by the edta•Mg-Al LDH at the pH of 5.0. The function of edta anions as chelator is considered to be adequately active in the interlayer of edta•Mg-Al LDH. Citrate•Mg–Al LDH, malate•Mg–Al LDH, or tartrate•Mg–Al LDH, which had citrate^3–(C₆H₅O₇^3–), malate^2–(C₄H₄O₅^2–), or tartrate^2–(C₄H₄O₆^2–) anions intercalated in the interlayer, were also found to take up Cu²⁺ and Cd²⁺ rapidly from an aqueous solution at a constant pH of 5.0. This capacity was mainly attributable to the formation of the citrate–metal, malate–metal, and tartrate–metal complexes in the interlayers of the Mg–Al LDHs. The citrate^3–, malate^2–, and tartrate^2– were adequately active as chelator in the interlayers of Mg–Al LDHs.
Keywords: Layered double hydroxides; Chelator, Uptake; Metal ion