Preparation of Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate by coprecipitation and its uptake of rare earth ions from aqueous solution

摘要

A Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta·Cu-Al LDH) was prepared by the dropwise addition of a Cu-Al nitrate solution to an edta solution at constant pH values of 8.0, 9.0, and 10.0. The edta·Cu-Al LDH had Hedta~(3-) in the interlayer. Furthermore, the preparation at pH 8.0 resulted in the intercalation of Cu(edta)~(2-). The edta?Cu-Al LDH was found to take up rare earth ions from aqueous solution. The uptake of Sc~(3+) and Y~(3+) by edta.Cu-Al LDH was attributed to both the chelating functions of the edta ion in the interlayer and the chemical properties of Cu-Al LDH itself. The uptake of La~(3+) by edta·Cu-Al LDH was primarily caused by the chelating function of edta ions in the interlayer. The edta ions in the edta·Cu-Al LDH interlayer formed chelate complexes in the order Sc~(3+) > Y~(3+) > 1~(3+) due to their relative stabilities, Sc(edta)~- > Y(edta)~ > La(edta)~-. Thus, edta ions retain their chelating function even when intercalated in a Cu-Al LDH interlayer.