We report on aqueous Cu2 uptake by NiAl layered double hydroxides (NiAl LDHs) modified with citrate (C6H5O 73-), malate (C4H4O5 2-), and tartrate (C4H4O6 2-) anions via coprecipitation. Dropwise addition of a mixed aqueous solution of Ni(NO3)2 and Al(NO3)3 to the respective organic acid solutions at a constant pH of 7.09.0 afforded LDHs with intercalated C6H5O73- and Ni(C6H5O7)-, C4H 4O52-, and C4H4O 62- in their interlayers. The anions were also likely adsorbed on the LDH surface. Citrate·NiAl LDH could rapidly take up Cu2 at a constant pH of 5.0, mainly via chelation by the intercalated and adsorbed anions, rather than coprecipitation with dissolved Al3 to form CuAl LDH. By contrast, malate and tartrate were not active as chelating agents, probably because they formed bridges between brucite-like layers by direct coordination of the two -COO- groups with Al3 in those layers.
- Chemical synthesis
- Inorganic compounds